Applied Sciences

0 pages, 6566 KiB

Open AccessArticle

Improved Ultrasonic Computerized Tomography Method for STS (Steel Tube Slab) Structure Based on Compressive Sampling Algorithm

by Baofeng Jiang^1,2, Wen Zhao¹ and Wentao Wang^3,*

¹ College of Resource and Civil Engineering, Northeastern University, Shenyang 110819, China

² Shenyang Metro Co., Ltd., Shenyang 110011, China

³ Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, MI 48109-2125, USA

Appl. Sci. 2017, 7(5), 432; https://doi.org/10.3390/app7050432 - 26 Apr 2017

Cited by 14 | Viewed by 5520

Abstract

This paper developed a new ultrasonic computerized tomography (CT) method for damage inspections of a steel tube slab (STS) structure based on compressive sampling (CS). CS is a mathematic theory providing an approximate recovery for a sparse signal with minimal reconstruction error from [...] Read more.

This paper developed a new ultrasonic computerized tomography (CT) method for damage inspections of a steel tube slab (STS) structure based on compressive sampling (CS). CS is a mathematic theory providing an approximate recovery for a sparse signal with minimal reconstruction error from under-sampled measurements. Considering the natural sparsity of the damage, CS algorithm is employed to image the defect in the concrete-filled steel tube of Shenyang Metro line 9 for reducing the work time. Thus, in the measurement stage, far fewer ultrasonic measurement paths were selected from the dense net of conventional ultrasonic CT techniques to capture the underlying damage information. Then, in the imaging stage, ℓ₁-norm minimization algorithm of CS theory is selected to recover the internal damage via fusing measurement data and solving optimization problem. The functionality of the proposed method is validated by three numerical concrete tube models with various conditions. Additionally, both the conventional ultrasonic CT technique and the proposed one are employed for ultrasonic inspection of the STS structure in Shenyang Metro line 9. Both the numerical and experimental results indicate that the proposed ultrasonic CT improved by CS has a great potential for damage detection, which provides an alternative accurate and effective way for non-destructive testing/evaluation (NDT/E). Full article

(This article belongs to the Special Issue Advances in Acoustic Emission and Health Monitoring of Materials and Structures)

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14 pages, 6365 KiB

Open AccessFeature PaperArticle

Formation of Boundary Film from Ionic Liquids Enhanced by Additives

by Erik Nyberg^1,*

, Johanne Mouzon²

, Mattias Grahn² and Ichiro Minami¹

¹ Division of Machine Elements, Department of Engineering Sciences and Mathematics, Luleå University of Technology, Luleå SE-97187, Sweden

² Chemical Technology, Luleå University of Technology, Luleå SE-97187, Sweden

Appl. Sci. 2017, 7(5), 433; https://doi.org/10.3390/app7050433 - 26 Apr 2017

Cited by 11 | Viewed by 5527

Abstract

Room temperature ionic liquids (RTILs) have several properties that make them interesting candidates as base fluids for extreme conditions. However, a lack of compatibility with tribo-improving additives combined with an often overly aggressive nature is limiting their use as base fluids. To overcome [...] Read more.

Room temperature ionic liquids (RTILs) have several properties that make them interesting candidates as base fluids for extreme conditions. However, a lack of compatibility with tribo-improving additives combined with an often overly aggressive nature is limiting their use as base fluids. To overcome these drawbacks, hydrocarbon-imitating RTIL base fluids have recently been developed. In this study, the effects of several common additives in the novel RTIL (P-SiSO) were examined by laboratory tribotesting. A reciprocating steel-steel ball-on-flat setup in an air atmosphere was used, where the lubricant performance was evaluated over a range of loads and temperatures. Surface analyses after testing were carried out using optical profilometry, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Neat P-SiSO displayed high performance in the tribotests. At an elevated load and temperature, a shift in lubrication mode was observed with an accompanying increase in friction and wear. Surface analysis revealed a boundary film rich in Si and O in the primary lubrication mode, while P was detected after a shift to the secondary lubrication mode. An amine additive was effective in reducing wear and friction under harsh conditions. The amine was determined to increase formation of the protective Si–O film, presumably by enhancing the anion activity. Full article

(This article belongs to the Special Issue Lubricant Additives)

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7 pages, 1931 KiB

Open AccessArticle

A Resonantly Pumped Single-Longitudinal Mode Ho:Sc₂SiO₅ Laser with Two Fabry–Perot Etalons

by Xiao-Tao Yang, Long Liu^*, Peng Zhang and Wen-Qiang Xie

College of Power and Energy Engineering, Harbin Engineering University, Harbin 150001, China

Appl. Sci. 2017, 7(5), 434; https://doi.org/10.3390/app7050434 - 25 Apr 2017

Cited by 10 | Viewed by 4933

Abstract

We present a single-longitudinal-mode Ho:Sc₂SiO₅ (Ho:SSO) laser pumped by a Tm:YAP laser for the first time. Two intra-cavity Fabry–Perot etalons were used to realize the single-longitudinal mode of operation. The maximum output power of 590 mW at 2111.91 nm was [...] Read more.

We present a single-longitudinal-mode Ho:Sc₂SiO₅ (Ho:SSO) laser pumped by a Tm:YAP laser for the first time. Two intra-cavity Fabry–Perot etalons were used to realize the single-longitudinal mode of operation. The maximum output power of 590 mW at 2111.91 nm was obtained with the incident power of 10.2 W, when the slope efficiency was 9.7% and the optical conversion efficiency was 5.8%. The M² factor of the single longitudinal mode Ho:SSO laser was measured to be 1.17. Full article

(This article belongs to the Section Optics and Lasers)

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16 pages, 4043 KiB

Open AccessArticle

A TSVD-Based Method for Forest Height Inversion from Single-Baseline PolInSAR Data

by Dongfang Lin, Jianjun Zhu^*, Haiqiang Fu, Qinghua Xie and Bing Zhang

School of Geosciences and Info-Physics, Central South University, Changsha 410083, China

Appl. Sci. 2017, 7(5), 435; https://doi.org/10.3390/app7050435 - 25 Apr 2017

Cited by 9 | Viewed by 5390

Abstract

The random volume over ground (RVoG) model associates vegetation vertical structure parameters with multiple complex interferometric coherence observables. In this paper, on the basis of the RVoG model, a truncated singular value decomposition (TSVD)-based method is proposed for forest height inversion from single-baseline [...] Read more.

The random volume over ground (RVoG) model associates vegetation vertical structure parameters with multiple complex interferometric coherence observables. In this paper, on the basis of the RVoG model, a truncated singular value decomposition (TSVD)-based method is proposed for forest height inversion from single-baseline polarimetric interferometric synthetic aperture radar (PolInSAR) data. In addition, in order to improve the applicability of TSVD for this issue, a new truncation method is proposed for TSVD. Differing from the traditional three-stage method, the TSVD-based inversion method estimates the pure volume coherence directly from the complex interferometric coherence, and estimates the forest height from the estimated pure volume coherence with a least-squares method. As a result, the TSVD-based method can adjust the contributions of the polarizations in the estimation of the model parameters and avoid the null ground-to-volume ratio assumption. The simulated experiments undertaken in this study confirmed that the TSVD-based method performs better than the three-stage method in forest height inversion. The TSVD-based method was also applied to E-SAR P-band data acquired over the Krycklan Catchment, Sweden, which is covered with mixed pine forest. The results showed that the TSVD-based method improves the root-mean-square error by 48.6% when compared to the three-stage method, which further validates the performance of the TSVD-based method. Full article

(This article belongs to the Special Issue Polarimetric SAR Techniques and Applications)

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21 pages, 5632 KiB

Open AccessArticle

Improved Image Denoising Algorithm Based on Superpixel Clustering and Sparse Representation

by Hai Wang^1,*, Xue Xiao², Xiongyou Peng²

, Yan Liu² and Wei Zhao²

¹ School of Aerospace Science and Technology, Xidian University, Xi’an 710071, China

² School of Electro-Mechanical Engineering, Xidian University, Xi’an 710071, China

Appl. Sci. 2017, 7(5), 436; https://doi.org/10.3390/app7050436 - 26 Apr 2017

Cited by 9 | Viewed by 5120

Abstract

Good learning image priors from the noise-corrupted images or clean natural images are very important in preserving the local edge and texture regions while denoising images. This paper presents a novel image denoising algorithm based on superpixel clustering and sparse representation, named as [...] Read more.

Good learning image priors from the noise-corrupted images or clean natural images are very important in preserving the local edge and texture regions while denoising images. This paper presents a novel image denoising algorithm based on superpixel clustering and sparse representation, named as the superpixel clustering and sparse representation (SC-SR) algorithm. In contrast to most existing methods, the proposed algorithm further learns image nonlocal self-similarity (NSS) prior with mid-level visual cues via superpixel clustering by the sparse subspace clustering method. As the superpixel edges adhered to the image edges and reflected the image structural features, structural and edge priors were considered for a better exploration of the NSS prior. Next, each similar superpixel region was regarded as a searching window to seek the first

L

most similar patches to each local patch within it. For each similar superpixel region, a specific dictionary was learned to obtain the initial sparse coefficient of each patch. Moreover, to promote the effectiveness of the sparse coefficient for each patch, a weighted sparse coding model was constructed under a constraint of weighted average sparse coefficient of the first

L

most similar patches. Experimental results demonstrated that the proposed algorithm achieved very competitive denoising performance, especially in image edges and fine structure preservation in comparison with state-of-the-art denoising algorithms. Full article

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12 pages, 3730 KiB

Open AccessArticle

Hybrid Electric Vehicle Performance with Organic Rankine Cycle Waste Heat Recovery System

by Amin Mahmoudzadeh Andwari^1,2,*

, Apostolos Pesiridis¹, Apostolos Karvountzis-Kontakiotis¹ and Vahid Esfahanian²

¹ Centre for Advanced Powertrain and Fuels Research (CAPF), Department of Mechanical, Aerospace and Civil Engineering, Brunel University London, London UB8 3PH, UK

² Vehicle, Fuel and Environment Research Institute, School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran 1439956191, Iran

Appl. Sci. 2017, 7(5), 437; https://doi.org/10.3390/app7050437 - 26 Apr 2017

Cited by 32 | Viewed by 13585

Abstract

This study examines the implementation of a waste heat recovery system on an electric hybrid vehicle. The selected waste heat recovery method operates on organic Rankine cycle principles to target the overall fuel consumption improvement of the internal combustion engine element of a [...] Read more.

This study examines the implementation of a waste heat recovery system on an electric hybrid vehicle. The selected waste heat recovery method operates on organic Rankine cycle principles to target the overall fuel consumption improvement of the internal combustion engine element of a hybrid powertrain. This study examines the operational principle of hybrid electric vehicles, in which the internal combustion engines operates with an electric powertrain layout (electric motors/generators and batteries) as an integral part of the powertrain architecture. A critical evaluation of the performance of the integrated powertrain is presented in this paper whereby vehicle performance is presented through three different driving cycle tests, offering a clear assessment of how this advanced powertrain configuration would benefit under several different, but relevant, driving scenarios. The driving cycles tested highlighted areas where the driver could exploit the full potential of the hybrid powertrain operational modes in order to further reduce fuel consumption. Full article

(This article belongs to the Special Issue Internal Combustion Engines (ICE) for Ground Transport)

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19 pages, 3526 KiB

Open AccessArticle

Novel Genetic Algorithm-Based Energy Management in a Factory Power System Considering Uncertain Photovoltaic Energies

by Ying-Yi Hong^*

and Po-Sheng Yo

Department of Electrical Engineering, Chung Yuan Christian University, Taoyuan 32023, Taiwan

Appl. Sci. 2017, 7(5), 438; https://doi.org/10.3390/app7050438 - 26 Apr 2017

Cited by 15 | Viewed by 5821

Abstract

The demand response and accommodation of different renewable energy resources are essential factors in a modern smart microgrid. This paper investigates the energy management related to the short-term (24 h) unit commitment and demand response in a factory power system with uncertain photovoltaic [...] Read more.

The demand response and accommodation of different renewable energy resources are essential factors in a modern smart microgrid. This paper investigates the energy management related to the short-term (24 h) unit commitment and demand response in a factory power system with uncertain photovoltaic power generation. Elastic loads may be activated subject to their operation constraints in a manner determined by the electricity prices while inelastic loads are inflexibly fixed in each hour. The generation of power from photovoltaic arrays is modeled as a Gaussian distribution owing to its uncertainty. This problem is formulated as a stochastic mixed-integer optimization problem and solved using two levels of algorithms: the master level determines the optimal states of the units (e.g., micro-turbine generators) and elastic loads; and the slave level concerns optimal real power scheduling and power purchase/sale from/to the utility, subject to system operating constraints. This paper proposes two novel encoding schemes used in genetic algorithms on the master level; the point estimate method, incorporating the interior point algorithm, is used on the slave level. Various scenarios in a 30-bus factory power system are studied to reveal the applicability of the proposed method. Full article

(This article belongs to the Special Issue Computational Intelligence in Photovoltaic Systems)

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21 pages, 2128 KiB

Open AccessArticle

A New Robust Tracking Control Design for Turbofan Engines: H_∞/Leitmann Approach

by Muxuan Pan¹

, Kaiwen Zhang¹, Ye-Hwa Chen² and Jinquan Huang^1,*

¹ College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, Jiangsu, China

² The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30324, USA

Appl. Sci. 2017, 7(5), 439; https://doi.org/10.3390/app7050439 - 27 Apr 2017

Cited by 17 | Viewed by 4263

Abstract

In this paper, a

H_{\infty}

/Leitmann approach to the robust tracking control design is presented for an uncertain dynamic system. This new method is developed in the following two steps. Firstly, a tracking dynamic system with simultaneous consideration of parameter uncertainty and [...] Read more.

In this paper, a

H_{\infty}

/Leitmann approach to the robust tracking control design is presented for an uncertain dynamic system. This new method is developed in the following two steps. Firstly, a tracking dynamic system with simultaneous consideration of parameter uncertainty and noise is modeled based on a linear system and a reference model. Accordingly, a “nominal system” from the tracking system is defined and controlled by a

H_{\infty}

control to obtain the asymptotical stability and noise resistance. Secondly, by making use of a Lyapunov function and the norm boundedness, a new robust control with the “Leitmann approach” is designed to cope with the uncertainty. The two controls collaborate with each other to achieve “uniform tracking boundedness” and “uniform ultimate tracking boundedness”. The new approach is then applied to an aircraft turbofan control design, and the numerical simulation results show the prescribed performances of the closed-loop system and the advantage of the developed approach. Full article

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8 pages, 3589 KiB

Open AccessArticle

Improvement of Interfacial Adhesion of Incorporated Halloysite-Nanotubes in Fiber-Reinforced Epoxy-Based Composites

by Jin-Woo Lee¹

, Soo-Jeong Park² and Yun-Hae Kim^1,*

¹ Department of Mechanical Engineering, Korea Maritime and Ocean University, Busan 49112, Korea

² Department of Material Engineering, Graduate School, Korea Maritime and Ocean University, Busan 49112, Korea

Appl. Sci. 2017, 7(5), 441; https://doi.org/10.3390/app7050441 - 27 Apr 2017

Cited by 11 | Viewed by 5303

Abstract

The heart of composite materials depends on the characteristics of their interface. The physical properties of composite materials are often described by the rule of mixtures, representing the average physical properties of the reinforcement and the matrix resin. However, in practical applications there [...] Read more.

The heart of composite materials depends on the characteristics of their interface. The physical properties of composite materials are often described by the rule of mixtures, representing the average physical properties of the reinforcement and the matrix resin. However, in practical applications there are situations which arise where the rule of mixtures is not followed. This is because when an external energy applied to the composite material is transferred from the matrix to the reinforcement, the final physical properties are affected by the interface between them rather than the intrinsic properties of both the reinforcement and the matrix. The internal bonding strength of the interface of these composites can be enhanced by enhancing the bonding strength by adding a small amount of material at the interface. In this study, the mechanical properties were evaluated by producing a carbon fiber-reinforced composite material and improved by dispersing halloysite nanotubes (HNTs) and the epoxy resin using an ultrasonic homogenizer. The interfacial bond strength increased with the addition of HNT. On the other hand, the addition of HNTs more than 3 wt % did not show the reinforcing effect by HNT agglomeration. Full article

(This article belongs to the Special Issue Surface Modification of Halloysite Nanotubes)

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9 pages, 4057 KiB

Open AccessFeature PaperArticle

Polarization Properties of Laser Solitons

by Pedro Rodriguez^1,*,†, Jesus Jimenez^2,†, Thierry Guillet^2,3,†

and Thorsten Ackemann^2,†

¹ Physics Department, University of Cordoba, Cordoba, 14071 Andalusia, Spain

² SUPA and Department of Physics, University of Strathclyde, Glasgow G4 0NG, Scotland, UK

³ Laboratoire Charles Coulomb, UMR 5221 CNRS, Universite de Montpellier, 163 Rue Auguste Broussonnet, 34090 Montpellier, France

^† The authors contributed equally to this work.

Appl. Sci. 2017, 7(5), 442; https://doi.org/10.3390/app7050442 - 27 Apr 2017

Cited by 3 | Viewed by 5588

Abstract

The objective of this paper is to summarize the results obtained for the state of polarization in the emission of a vertical-cavity surface-emitting laser with frequency-selective feedback added. We start our research with the single soliton; this situation presents two perpendicular main orientations, [...] Read more.

The objective of this paper is to summarize the results obtained for the state of polarization in the emission of a vertical-cavity surface-emitting laser with frequency-selective feedback added. We start our research with the single soliton; this situation presents two perpendicular main orientations, connected by a hysteresis loop. In addition, we also find the formation of a ring-shaped intensity distribution, the vortex state, that shows two homogeneous states of polarization with very close values to those found in the soliton. For both cases above, the study shows the spatially resolved value of the orientation angle. It is important to also remark the appearance of a non-negligible amount of circular light that gives vectorial character to all the different emissions investigated. Full article

(This article belongs to the Special Issue Guided-Wave Optics)

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14 pages, 1777 KiB

Open AccessArticle

Chemical Constituents and Biological Activities of Essential Oils of Hydnora africana Thumb Used to Treat Associated Infections and Diseases in South Africa

by Olubunmi Abosede Wintola

and Anthony Jide Afolayan^*

Medicinal Plants and Economic Development (MPED) Research Centre, Department of Botany, University of Fort Hare, Alice 5700, South Africa

Appl. Sci. 2017, 7(5), 443; https://doi.org/10.3390/app7050443 - 27 Apr 2017

Cited by 19 | Viewed by 7233

Abstract

Hydnora africana (HA) Thumb is a member of the genus Hydnora. The roots are used in the treatment of infectious diseases in South Africa folk medicine. Though the root extracts are used to treat various human diseases including inflamed throat, there [...] Read more.

Hydnora africana (HA) Thumb is a member of the genus Hydnora. The roots are used in the treatment of infectious diseases in South Africa folk medicine. Though the root extracts are used to treat various human diseases including inflamed throat, there is a dearth of scientific data on the biological activities of essential oil isolated from this plant in the literature. Therefore, the present study was conducted to determine the chemical components and certain biological activities of the essential oil using standard bioassay methods. The plant essential oil exhibited a moderate free radical scavenging activity that was dependent on the radical species. Similarly, the essential oil was active against the growth of all thirteen opportunistic bacteria apart from Salmonella typhimurium, Pseudomonas aeruginosa and Proteus vulgaris. The essential oil was also active against Aspergillus niger among all the nine fungi selected. In addition, the species is typified by substantial amounts of classes of compounds including; carboxylic acids (30.68%), terpenes (10.70%), alkyl aldehydes (4.86%) and esters (0.82%), identified as antioxidant and antimicrobial agents. The essential oil of H. africana could be said to have pharmacological properties, and these agents in the essential oil of H. africana could justify the folklore usage of this plant in the treatment of infections and related diseases. Full article

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10 pages, 3659 KiB

Open AccessArticle

Improved Imaging of Magnetically Labeled Cells Using Rotational Magnetomotive Optical Coherence Tomography

by Peter Cimalla^1,2, Julia Walther^1,3

, Claudia Mueller⁴, Seba Almedawar², Bernd Rellinghaus⁵, Dierk Wittig⁴, Marius Ader², Mike O. Karl^2,6, Richard H. W. Funk⁴, Michael Brand² and Edmund Koch^1,*

¹ Anesthesiology and Intensive Care Medicine, Clinical Sensoring and Monitoring, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany

² DFG-Center for Regenerative Therapies Dresden (CRTD), Technische Universität Dresden, 01307 Dresden, Germany

³ Department of Medical Physics and Biomedical Engineering, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany

⁴ Institute of Anatomy, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany

⁵ Institute for Metallic Materials, Leibniz Institute for Solid State and Materials Research, 01069 Dresden, Germany

⁶ German Center for Neurodegenerative Diseases (DZNE), 01307 Dresden, Germany

Appl. Sci. 2017, 7(5), 444; https://doi.org/10.3390/app7050444 - 27 Apr 2017

Cited by 7 | Viewed by 6145

Abstract

In this paper, we present a reliable and robust method for magnetomotive optical coherence tomography (MM-OCT) imaging of single cells labeled with iron oxide particles. This method employs modulated longitudinal and transverse magnetic fields to evoke alignment and rotation of anisotropic magnetic structures [...] Read more.

In this paper, we present a reliable and robust method for magnetomotive optical coherence tomography (MM-OCT) imaging of single cells labeled with iron oxide particles. This method employs modulated longitudinal and transverse magnetic fields to evoke alignment and rotation of anisotropic magnetic structures in the sample volume. Experimental evidence suggests that magnetic particles assemble themselves in elongated chains when exposed to a permanent magnetic field. Magnetomotion in the intracellular space was detected and visualized by means of 3D OCT as well as laser speckle reflectometry as a 2D reference imaging method. Our experiments on mesenchymal stem cells embedded in agar scaffolds show that the magnetomotive signal in rotational MM-OCT is significantly increased by a factor of ~3 compared to previous pulsed MM-OCT, although the solenoid’s power consumption was 16 times lower. Finally, we use our novel method to image ARPE-19 cells, a human retinal pigment epithelium cell line. Our results permit magnetomotive imaging with higher sensitivity and the use of low power magnetic fields or larger working distances for future three-dimensional cell tracking in target tissues and organs. Full article

(This article belongs to the Special Issue Development and Application of Optical Coherence Tomography (OCT))

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33 pages, 9163 KiB

Open AccessReview

Molecular Science of Lubricant Additives

by Ichiro Minami^†

¹ Division of Machine Elements, Luleå University of Technology, 97187 Luleå, Sweden

^† Dedicated to the late Professor Keiji Yamamoto in memory of his contributions to organo-silicon chemistry.

Appl. Sci. 2017, 7(5), 445; https://doi.org/10.3390/app7050445 - 28 Apr 2017

Cited by 144 | Viewed by 20484

Abstract

This review aims at introducing an engineering field of lubrication to researchers who are not familiar with tribology, thereby emphasizing the importance of lubricant chemistry in applied science. It provides initial guidance regarding additive chemistry in lubrication systems for researchers with different backgrounds. [...] Read more.

This review aims at introducing an engineering field of lubrication to researchers who are not familiar with tribology, thereby emphasizing the importance of lubricant chemistry in applied science. It provides initial guidance regarding additive chemistry in lubrication systems for researchers with different backgrounds. The readers will be introduced to molecular sciences underlying lubrication engineering. Currently, lubricant chemistry, especially “additive technology”, looks like a very complicated field. It seems that scientific information is not always shared by researchers. The cause of this is that lubrication engineering is based on empirical methods and focuses on market requirements. In this regard, engineering knowhow is held by individuals and is not being disclosed to scientific communities. Under these circumstances, a bird’s-eye view of lubricant chemistry in scientific words is necessary. The novelty of this review is to concisely explain the whole picture of additive technology in chemical terms. The roles and functions of additives as the leading actors in lubrication systems are highlighted within the scope of molecular science. First, I give an overview of the fundamental lubrication model and the role of lubricants in machine operations. The existing additives are categorized by the role and work mechanism in lubrication system. Examples of additives are shown with representative molecular structure. The second half of this review explains the scientific background of the lubrication engineering. It includes interactions of different components in lubrication systems. Finally, this review predicts the technical trends in lubricant chemistry and requirements in molecular science. This review does not aim to be a comprehensive chart or present manufacturing knowhow in lubrication engineering. References were carefully selected and cited to extract “the most common opinion” in lubricant chemistry and therefore many engineering articles were omitted for conciseness. Full article

(This article belongs to the Special Issue Lubricant Additives)

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21 pages, 6133 KiB

Open AccessArticle

A Multi-View Stereo Algorithm Based on Homogeneous Direct Spatial Expansion with Improved Reconstruction Accuracy and Completeness

by Yalan Li^1,2 and Zhiyang Li^1,*

¹ College of Physical Science and Technology, Central China Normal University, Wuhan 430079, China

² School of Electronic Information and Electrical Engineering, Xiangnan University, Chenzhou 423000, China

Appl. Sci. 2017, 7(5), 446; https://doi.org/10.3390/app7050446 - 29 Apr 2017

Cited by 6 | Viewed by 5298

Abstract

Reconstruction of 3D structures from multiple 2D images has wide applications in such fields as computer vision, cultural heritage preservation, etc. This paper presents a novel multi-view stereo algorithm based on homogeneous direct spatial expansion (MVS-HDSE) with high reconstruction accuracy and completeness. It [...] Read more.

Reconstruction of 3D structures from multiple 2D images has wide applications in such fields as computer vision, cultural heritage preservation, etc. This paper presents a novel multi-view stereo algorithm based on homogeneous direct spatial expansion (MVS-HDSE) with high reconstruction accuracy and completeness. It adopts many unique measures in each step of reconstruction, including initial seed point extraction using the DAISY descriptor to increase the number of initial sparse seed points, homogeneous direct spatial expansion to enhance efficiency, initial value modification via a conditional-double-surface-fitting method before optimization and adaptive consistency filtering after optimization to ensure high accuracy, processing using a multi-level image pyramid to further improve completeness and efficiency, etc. As demonstrated by experiments, owing to above measures the proposed algorithm attained much improved reconstruction completeness and accuracy. Full article

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18 pages, 3647 KiB

Open AccessArticle

Dual-Branch Deep Convolution Neural Network for Polarimetric SAR Image Classification

by Fei Gao¹, Teng Huang^1,2

, Jun Wang^1,*, Jinping Sun¹

, Amir Hussain³ and Erfu Yang⁴

¹ School of Electronic and Information Engineering, Beihang University, Beijing 100191, China

² Department of Computer and Electronic Engineering, Wuzhou University, Wuzhou 543000, China

³ Cognitive Signal-Image and Control Processing Research Laboratory, School of Natural Sciences University of Stirling, Stirling FK9 4LA, UK

⁴ Space Mechatronic System Technology Laboratory, Department of Design, Manufacture and Engineering Management University of Strathclyde, Glasgow G1 1XJ, UK

Appl. Sci. 2017, 7(5), 447; https://doi.org/10.3390/app7050447 - 27 Apr 2017

Cited by 93 | Viewed by 12049

Abstract

The deep convolution neural network (CNN), which has prominent advantages in feature learning, can learn and extract features from data automatically. Existing polarimetric synthetic aperture radar (PolSAR) image classification methods based on the CNN only consider the polarization information of the image, instead [...] Read more.

The deep convolution neural network (CNN), which has prominent advantages in feature learning, can learn and extract features from data automatically. Existing polarimetric synthetic aperture radar (PolSAR) image classification methods based on the CNN only consider the polarization information of the image, instead of incorporating the image’s spatial information. In this paper, a novel method based on a dual-branch deep convolution neural network (Dual-CNN) is proposed to realize the classification of PolSAR images. The proposed method is built on two deep CNNs: one is used to extract the polarization features from the 6-channel real matrix (6Ch) which is derived from the complex coherency matrix. The other is utilized to extract the spatial features of a Pauli RGB (Red Green Blue) image. These extracted features are first combined into a fully connected layer sharing the polarization and spatial property. Then, the Softmax classifier is employed to classify these features. The experiments are conducted on the Airborne Synthetic Aperture Radar (AIRSAR) data of Flevoland and the results show that the classification accuracy on 14 types of land cover is up to 98.56%. Such results are promising in comparison with other state-of-the-art methods. Full article

(This article belongs to the Special Issue Polarimetric SAR Techniques and Applications)

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12 pages, 2142 KiB

Open AccessArticle

Experimental Study on Heat Transfer Performance of Vacuum Tube Heat Collector with Thermal Storage

by Xinpeng Huang^1,2, Zhenqian Chen^1,2,* and Juan Shi¹

¹ School of Energy and Environment, Southeast University, Nanjing 210096, China

² Jiangsu Provincial Key Laboratory of Solar Energy Technology, Nanjing 210096, China

Appl. Sci. 2017, 7(5), 448; https://doi.org/10.3390/app7050448 - 28 Apr 2017

Cited by 6 | Viewed by 5629

Abstract

This experimental study is intended to explore the heat performance of a novel vacuum tube heat collector with thermal storage. In order to enhance the heat transfer performance, we add radial metal fins to the U-tube which is used as the heat transfer [...] Read more.

This experimental study is intended to explore the heat performance of a novel vacuum tube heat collector with thermal storage. In order to enhance the heat transfer performance, we add radial metal fins to the U-tube which is used as the heat transfer channel of water. Meanwhile, in order to increase the thermal capacity of the heat collector, the heat collector model is designed to be larger than the general collector and is filled with the phase change materials (PCMs). In the U-tube, paraffin is chosen as the PCM. Then, during the experiment, to study the energy absorption and desorption characteristics of the heat collector, we chose to test during the day and night in the summer and the transition season. The experimental results show that, at night, the outlet water temperature of the vacuum tube heat collector has been enhanced by using PCM. The outlet water temperature decreases with the increase of flow rate. Full article

(This article belongs to the Special Issue Advances in Thermal System Analysis and Optimization)

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15 pages, 4155 KiB

Open AccessArticle

Evaluation of a Simplified Method to Estimate the Peak Inter-Story Drift Ratio of Steel Frames with Hysteretic Dampers

by Jae-Do Kang^1,* and Yasuhiro Mori²

¹ Earthquake Disaster Mitigation Research Division, National Research Institute for Earth Science and Disaster Resilience, Miki 673-0515, Japan

² Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8603, Japan

Appl. Sci. 2017, 7(5), 449; https://doi.org/10.3390/app7050449 - 27 Apr 2017

Cited by 7 | Viewed by 6735

Abstract

In this paper, a simplified method is proposed to estimate the peak inter-story drift ratios of steel frames with hysteretic dampers. The simplified method involved the following: (1) the inelastic spectral displacement is estimated using a single-degree-of-freedom (SDOF) system with multi-springs, which is [...] Read more.

In this paper, a simplified method is proposed to estimate the peak inter-story drift ratios of steel frames with hysteretic dampers. The simplified method involved the following: (1) the inelastic spectral displacement is estimated using a single-degree-of-freedom (SDOF) system with multi-springs, which is equivalent to a steel frame with dampers and in which multi-springs represent the hysteretic behavior of dampers; (2) the first inelastic mode vector is estimated using a pattern of story drifts obtained from nonlinear static pushover analysis; and (3) the effects of modes higher than the first mode are estimated by using the jth modal period, jth mode vector, and jth modal damping ratio obtained from eigenvalue analysis. The accuracy of the simplified method is estimated using the results of nonlinear time history analysis (NTHA) on a series of three-story, six-story, and twelve-story steel moment resisting frames with steel hysteretic dampers. Based on the results of a comparison of the peak inter-story drift ratios estimated by the simplified method and that computed via NTHA using an elaborate analytical model, the accuracy of the simplified method is sufficient for evaluating seismic demands. Full article

(This article belongs to the Special Issue Energy Dissipation and Vibration Control: Modeling, Algorithm and Devices)

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11 pages, 4027 KiB

Open AccessArticle

Shear Strengths of Different Bolt Connectors on the Large Span of Aluminium Alloy Honeycomb Sandwich Structure

by Caiqi Zhao^*, Weidong Zheng, Jun Ma and Yangjian Zhao

Key Laboratory of Concrete and Prestressed Concrete Structure, Ministry of Education, School of Civil Engineering, Southeast University, Nanjing 210096, China

Appl. Sci. 2017, 7(5), 450; https://doi.org/10.3390/app7050450 - 27 Apr 2017

Cited by 20 | Viewed by 6621

Abstract

This study investigates the shear capacity of aluminum alloy honeycomb sandwich plates connected by high-strength, ordinary, or self-tapping bolts. For that purpose, experimental tests and finite elements are carried out. The failure of a high-strength bolt connector is driven by bending deformations developed [...] Read more.

This study investigates the shear capacity of aluminum alloy honeycomb sandwich plates connected by high-strength, ordinary, or self-tapping bolts. For that purpose, experimental tests and finite elements are carried out. The failure of a high-strength bolt connector is driven by bending deformations developed in the bolt that deform connection plate and pad openings. In the case of ordinary bolt connectors, stress concentration on the bolt shear surface causes a large shear deformation that finally leads to failure. In the case of self-tapping bolt connectors, the insufficient mechanical bite force of the screw thread yields the bolt misalignment and concentrates shear deformation. As a result, the high-strength bolt connector is the most efficient design solution. If the bolt hole edge distance is more than 1.5 times as much as the bolt diameter, the connection performance becomes insensitive to this parameter. The practical formula for evaluating the connector shear capacity is derived from experimental data. Full article

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11 pages, 3013 KiB

Open AccessArticle

Using Acoustic Emission Methods to Monitor Cement Composites during Setting and Hardening

by Libor Topolář^*

, Luboš Pazdera

, Barbara Kucharczyková

, Jaroslav Smutný and Karel Mikulášek

Faculty of Civil Engineering, Brno University of Technology, Veveří 331/95, Brno 602 00, Czech Republic

Appl. Sci. 2017, 7(5), 451; https://doi.org/10.3390/app7050451 - 28 Apr 2017

Cited by 26 | Viewed by 6698

Abstract

Cement-based composites belong among the basic building materials used in civil engineering. Their properties are given not only by their composition but also by their behaviour after mixing, as well as by the methods of curing. Monitoring the processes and phenomena during the [...] Read more.

Cement-based composites belong among the basic building materials used in civil engineering. Their properties are given not only by their composition but also by their behaviour after mixing, as well as by the methods of curing. Monitoring the processes and phenomena during the early stages of setting is vital for determining the resulting properties and durability. The acoustic emission method is a unique non-destructive method that can detect structural changes as a cement-based composite is setting. It can also detect the onset and growth of cracks during the service life of a cement-based composite since the moment it has been mixed. The paper discusses the use of the acoustic emission method with a focus on the early stage of the lifespan of a cement-based composite including the measures necessary for its use and description of the parameters of acoustic emission signals. Full article

(This article belongs to the Special Issue Advances in Acoustic Emission and Health Monitoring of Materials and Structures)

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18 pages, 7080 KiB

Open AccessArticle

Texture Analysis and Land Cover Classification of Tehran Using Polarimetric Synthetic Aperture Radar Imagery

by Homa Zakeri^*, Fumio Yamazaki and Wen Liu

Department of Urban Environment Systems, Chiba University, Chiba 263-8522, Japan

Appl. Sci. 2017, 7(5), 452; https://doi.org/10.3390/app7050452 - 29 Apr 2017

Cited by 51 | Viewed by 10213

Abstract

Land cover classification of built-up and bare land areas in arid or semi-arid regions from multi-spectral optical images is not simple, due to the similarity of the spectral characteristics of the ground and building materials. However, synthetic aperture radar (SAR) images could overcome [...] Read more.

Land cover classification of built-up and bare land areas in arid or semi-arid regions from multi-spectral optical images is not simple, due to the similarity of the spectral characteristics of the ground and building materials. However, synthetic aperture radar (SAR) images could overcome this issue because of the backscattering dependency on the material and the geometry of different surface objects. Therefore, in this paper, dual-polarized data from ALOS-2 PALSAR-2 (HH, HV) and Sentinel-1 C-SAR (VV, VH) were used to classify the land cover of Tehran city, Iran, which has grown rapidly in recent years. In addition, texture analysis was adopted to improve the land cover classification accuracy. In total, eight texture measures were calculated from SAR data. Then, principal component analysis was applied, and the first three components were selected for combination with the backscattering polarized images. Additionally, two supervised classification algorithms, support vector machine and maximum likelihood, were used to detect bare land, vegetation, and three different built-up classes. The results indicate that land cover classification obtained from backscatter values has better performance than that obtained from optical images. Furthermore, the layer stacking of texture features and backscatter values significantly increases the overall accuracy. Full article

(This article belongs to the Special Issue Polarimetric SAR Techniques and Applications)

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14 pages, 6225 KiB

Open AccessArticle

Damage Index Calibration of Frame-Supported Concealed Multi-Ribbed Wall Panels with Energy-Efficient Blocks

by Suizi Jia¹, Wanlin Cao^2,* and Yuchen Zhang³

¹ School of Engineering and Technology, China University of Geosciences (Beijing), No. 29, Xueyuan Road, Haidian District, Beijing 100083, China

² College of Architecture and Civil Engineering, Beijing University of Technology, No. 100, Pingleyuan, Chaoyang District, Beijing 100124, China

³ Academy of Railway Sciences, Scientific & Technological Information Research Institute, No. 2, Daliushu Road, Haidian District, Beijing 100081, China

Appl. Sci. 2017, 7(5), 453; https://doi.org/10.3390/app7050453 - 28 Apr 2017

Cited by 8 | Viewed by 4860

Abstract

In this paper, we carry out low-reversed cyclic loading tests on differently-structured frame-supported concealed multi-ribbed wall panels with energy-efficient blocks. Models for evaluating damage performance are introduced for comparative study, in an effort to identify the preferable model for such a structure. To [...] Read more.

In this paper, we carry out low-reversed cyclic loading tests on differently-structured frame-supported concealed multi-ribbed wall panels with energy-efficient blocks. Models for evaluating damage performance are introduced for comparative study, in an effort to identify the preferable model for such a structure. To this end, the paper uses OpenSees, a nonlinear finite element software that can accurately depict the mechanical performance of a structure, both to calculate the necessary mechanical parameters and to verify the damage model of interest. In this paper, we determine the numerical ranges for the damage index at different stages of accumulative damage, attaching detailed descriptions on a stage-by-stage basis. Then, we offer suggestions for structure restoration according to these indices. Full article

(This article belongs to the Section Materials Science and Engineering)

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20 pages, 5197 KiB

Open AccessArticle

Energy-Saving Network Ventilation Technology of Extra-Long Tunnel in Climate Separation Zone

by Chun Guo^1,*

, Jianfeng Xu¹, Lu Yang², Xiong Guo¹, Yunlong Zhang¹ and Mingnian Wang¹

¹ Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University, 111 Erhuan Rd, Chengdu 610031, China

² College of Foreign Languages, Southwest Jiaotong University, 111 Erhuan Rd, Chengdu 610031, China

Appl. Sci. 2017, 7(5), 454; https://doi.org/10.3390/app7050454 - 28 Apr 2017

Cited by 26 | Viewed by 5785

Abstract

Saving energy is a major challenge for the development and safety of the world. Researchers at home and abroad have been continuously working on energy saving technology in the tunnel ventilation for decades. Based on segmented longitudinal ventilation for extra-long road tunnels, the [...] Read more.

Saving energy is a major challenge for the development and safety of the world. Researchers at home and abroad have been continuously working on energy saving technology in the tunnel ventilation for decades. Based on segmented longitudinal ventilation for extra-long road tunnels, the main ventilation mode and utilization method of natural wind energy in extra-long road tunnel were analyzed in this paper. In addition, the possible velocity distribution of natural wind in each section under wind pressure was investigated. Principles of natural wind in each tunnel section were studied based on long-term monitored meteorological factors. Accordingly, a fan equipment configuration method with high guaranteed rate during tunnel operation was proposed. A calculation method for energy-saving network ventilation in the tunnels was established. A feasible and efficient optimized energy-saving ventilation strategy was proposed, which utilizes natural wind and reduces the operation energy consumption. Thus, the annual energy saving in ventilation can reach up to 43.2% compared to previous energy costs when the intelligent ventilation system works. The research results can properly combine natural wind energy with mechanical ventilation to realize the smart self-energy saving in extra-long tunnels. Full article

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15 pages, 5235 KiB

Open AccessArticle

Inverse Identification of the Frequency-Dependent Mechanical Parameters of a Viscoelastic Core Layer Based on the Vibration Response

by Wei Sun^*, Zhuo Wang, Rong Liu and Xianfei Yan

School of Mechanical Engineering & Automation, Northeastern University, Shenyang 110819, China

Appl. Sci. 2017, 7(5), 455; https://doi.org/10.3390/app7050455 - 28 Apr 2017

Cited by 18 | Viewed by 4545

Abstract

The identification of the mechanical parameters of the viscoelastic core layer is of great significance for the modeling and damping design of the constrained layer damping (CLD) composite structure. In this study, based on the measured frequency vibration response of a CLD plate, [...] Read more.

The identification of the mechanical parameters of the viscoelastic core layer is of great significance for the modeling and damping design of the constrained layer damping (CLD) composite structure. In this study, based on the measured frequency vibration response of a CLD plate, an inverse approach was developed to identify the aforementioned parameters. Then, on the basis of considering both the viscoelastic material damping and the remaining equivalent viscous damping, the equation of motion of the CLD plate under base excitation was established and a method to obtain the vibration response was also presented. Further, a matching calculation based on sensitivity was proposed, to achieve the identification of the mechanical parameters. Finally, a CLD aluminum plate with a ZN_1 viscoelastic core layer was chosen to demonstrate the proposed method. In addition, the identification results were also introduced into the vibration response analysis and the rationality of the identified parameters were verified by comparing the vibration responses obtained by theoretical calculations and the experiment. Full article

(This article belongs to the Section Mechanical Engineering)

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31 pages, 11137 KiB

Open AccessArticle

The Experimental Realization of an Acoustic Cloak in Air with a Meta-Composite Shell

by Shiuh-Kuang Yang¹, Jau-Cho Lin^1,2,*

and Jyin-Wen Cheng³

¹ Department of Mechanical and Electro-Mechanical Engineering, National Sun Yat-sen University, Kaohsiung 80424, Taiwan

² Architecture and Building Research Institute, Ministry of Interior, New Taipei City 23143, Taiwan

³ Cepstrum Technology Corporation, Kaohsiung 80245, Taiwan

Appl. Sci. 2017, 7(5), 456; https://doi.org/10.3390/app7050456 - 29 Apr 2017

Cited by 2 | Viewed by 5502

Abstract

Anisotropic cloak shells can be used for the spatial transformation of a space to alter the propagation of acoustic waves by redirecting them along a pre-determined path. This paper outlines the design, fabrication, and experimental analysis of a circular acoustic cloak shell made [...] Read more.

Anisotropic cloak shells can be used for the spatial transformation of a space to alter the propagation of acoustic waves by redirecting them along a pre-determined path. This paper outlines the design, fabrication, and experimental analysis of a circular acoustic cloak shell made of meta-composite material for in-air applications. Based on the three-dimensional coordinate transformation, we first designed an anisotropic circle meta-composite cloak shell according to its impedance values. The cloak shell comprises various layered structures with cavities and tubes, respectively, providing acoustic mass and compliance for the provision of anisotropic material properties. Secondly, we conducted numerical and experimental analyses under practice working conditions to demonstrate the efficacy of the acoustic cloak. The structure of the cloak shell, fabricated by three-dimensional printing (3D printing), is experimentally evaluated in a semi-anechoic room with a free-field environment. The simulation and experimental results demonstrate the acoustic cloaking effects in the scattering far field. Besides the scattering field, the sound field measurement results obtained with the region enclosed by the shell also shows the abilities of the cloak shell in altering the direction of wave propagation along a pre-determined path in air. Full article

(This article belongs to the Section Acoustics and Vibrations)

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21 pages, 8422 KiB

Open AccessArticle

Intent-Estimation- and Motion-Model-Based Collision Avoidance Method for Autonomous Vehicles in Urban Environments

by Rulin Huang^1,2, Huawei Liang^2,*, Pan Zhao², Biao Yu²

and Xinli Geng^1,2

¹ Department of Automation, University of Science and Technology of China, Hefei 230026, China

² Institute of Applied Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230026, China

Appl. Sci. 2017, 7(5), 457; https://doi.org/10.3390/app7050457 - 30 Apr 2017

Cited by 37 | Viewed by 7984

Abstract

Existing collision avoidance methods for autonomous vehicles, which ignore the driving intent of detected vehicles, thus, cannot satisfy the requirements for autonomous driving in urban environments because of their high false detection rates of collisions with vehicles on winding roads and the missed [...] Read more.

Existing collision avoidance methods for autonomous vehicles, which ignore the driving intent of detected vehicles, thus, cannot satisfy the requirements for autonomous driving in urban environments because of their high false detection rates of collisions with vehicles on winding roads and the missed detection rate of collisions with maneuvering vehicles. This study introduces an intent-estimation- and motion-model-based (IEMMB) method to address these disadvantages. First, a state vector is constructed by combining the road structure and the moving state of detected vehicles. A Gaussian mixture model is used to learn the maneuvering patterns of vehicles from collected data, and the patterns are used to estimate the driving intent of the detected vehicles. Then, a desirable long-term trajectory is obtained by weighting time and comfort. The long-term trajectory and the short-term trajectory, which are predicted using a constant yaw rate motion model, are fused to achieve an accurate trajectory. Finally, considering the moving state of the autonomous vehicle, collisions can be detected and avoided. Experiments have shown that the intent estimation method performed well, achieving an accuracy of 91.7% on straight roads and an accuracy of 90.5% on winding roads, which is much higher than that achieved by the method that ignores the road structure. The average collision detection distance is increased by more than 8 m. In addition, the maximum yaw rate and acceleration during an evasive maneuver are decreased, indicating an improvement in the driving comfort. Full article

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12 pages, 1636 KiB

Open AccessArticle

Perfect Light Absorbers Made of Tungsten-Ceramic Membranes

by Masanobu Iwanaga

National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba 305-0044, Japan

Appl. Sci. 2017, 7(5), 458; https://doi.org/10.3390/app7050458 - 29 Apr 2017

Cited by 11 | Viewed by 4514

Abstract

Plasmonic materials are expanding their concept; in addition to noble metals that are good conductors even at optical frequencies and support surface plasmon polaritons at the interface, other metals and refractory materials are now being used as plasmonic materials. In terms of complex [...] Read more.

Plasmonic materials are expanding their concept; in addition to noble metals that are good conductors even at optical frequencies and support surface plasmon polaritons at the interface, other metals and refractory materials are now being used as plasmonic materials. In terms of complex permittivity at optical frequencies, these new plasmonic materials are, though not ideal, quite good to support surface plasmons. Numerical investigations of the optical properties have been revealing new capabilities of the plasmonic materials. On the basis of the precise computations for electromagnetic waves in artificially designed nanostructures, in this article, we address membrane structures made of tungsten and silicon nitride that are a typical metal and ceramic, respectively, with high-temperature melting points. The membranes are applicable to low-power-consuming thermal emitters operating at and near the visible range. We numerically substantiate that the membranes serve as perfect light absorbers, in spite of the subwavelength thickness, that is, 200–250 nm thickness. Furthermore, we clarify that the underlying physical mechanism for the unconventional perfect absorption is ascribed to robust impedance matching at the interface between air and the membranes. Full article

(This article belongs to the Special Issue Guided-Wave Optics)

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16 pages, 568 KiB

Open AccessArticle

An Initial Load-Based Green Software Defined Network

by Ying Hu^1,*

, Tao Luo¹, Norman C. Beaulieu¹ and Wenjie Wang^2,†

¹ Beijing Key Laboratory of Network System Architecture and Convergence, Beijing University of Posts and Telecommunications, Beijing 100876, China

² Beijing Key Laboratory of Advanced Information Networks, Beijing University of Posts and Telecommunications, Beijing 100876, China

^† This paper is an extended version of our paper published in the 18th Asia-Pacific Network Operations and Management Symposium.

Appl. Sci. 2017, 7(5), 459; https://doi.org/10.3390/app7050459 - 2 May 2017

Cited by 12 | Viewed by 4502

Abstract

Software defined network (SDN) is a new network architecture in which the control function is decoupled from the data forwarding plane, that is attracting wide attentions from both research and industry sectors. However, SDN still faces the energy waste problem as do traditional [...] Read more.

Software defined network (SDN) is a new network architecture in which the control function is decoupled from the data forwarding plane, that is attracting wide attentions from both research and industry sectors. However, SDN still faces the energy waste problem as do traditional networks. At present, research on energy saving in SDN is mainly focused on the static optimization of the network with zero load when new traffic arrives, changing the transmission path of the uncompleted traffic which arrived before the optimization, possibly resulting in route oscillation and other deleterious effects. To avoid this, a dynamical energy saving optimization scheme in which the paths of the uncompleted flows will not be changed when new traffic arrives is designed. To find the optimal solution for energy saving, the problem is modeled as a mixed integer linear programming (MILP) problem. As the high complexity of the problem prohibits the optimal solution, an improved heuristic routing algorithm called improved constant weight greedy algorithm (ICWGA) is proposed to find a sub-optimal solution. Simulation results show that the energy saving capacity of ICWGA is close to that of the optimal solution, offering desirable improvement in the energy efficiency of the network. Full article

(This article belongs to the Special Issue Green Wireless Networks)

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25 pages, 4602 KiB

Open AccessArticle

Automated Diatom Classification (Part B): A Deep Learning Approach

by Anibal Pedraza¹

, Gloria Bueno^1,*

, Oscar Deniz¹

, Gabriel Cristóbal²

, Saúl Blanco³ and María Borrego-Ramos³

¹ VISILAB Research Group, University of Castilla La Mancha, Av. Camilo José Cela s/n, Ciudad Real 13071, Spain

² Institute of Optics, Spanish National Research Council (CSIC), Serrano 121, Madrid 8006, Spain

³ The Institute of the Environment, University of Leon, León E-24071, Spain

Appl. Sci. 2017, 7(5), 460; https://doi.org/10.3390/app7050460 - 2 May 2017

Cited by 103 | Viewed by 12604

Abstract

Diatoms, a kind of algae microorganisms with several species, are quite useful for water quality determination, one of the hottest topics in applied biology nowadays. At the same time, deep learning and convolutional neural networks (CNN) are becoming an extensively used technique for [...] Read more.

Diatoms, a kind of algae microorganisms with several species, are quite useful for water quality determination, one of the hottest topics in applied biology nowadays. At the same time, deep learning and convolutional neural networks (CNN) are becoming an extensively used technique for image classification in a variety of problems. This paper approaches diatom classification with this technique, in order to demonstrate whether it is suitable for solving the classification problem. An extensive dataset was specifically collected (80 types, 100 samples/type) for this study. The dataset covers different illumination conditions and it was computationally augmented to more than 160,000 samples. After that, CNNs were applied over datasets pre-processed with different image processing techniques. An overall accuracy of 99% is obtained for the 80-class problem and different kinds of images (brightfield, normalized). Results were compared to previous presented classification techniques with different number of samples. As far as the authors know, this is the first time that CNNs are applied to diatom classification. Full article

(This article belongs to the Special Issue Automated Analysis and Identification of Phytoplankton Images)

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20 pages, 1048 KiB

Open AccessArticle

Jointly Production and Correlated Maintenance Optimization for Parallel Leased Machines

by Tarek ASKRI^1,*, Zied HAJEJ¹ and Nidhal REZG^1,2

¹ Laboratory of Industrial Engineering Production and Maintenance, University of Lorraine, UFR MIM, île du Saulcy-BP 50128, 57045 Metz, France

² ICN Business School, 54003 Nancy-Metz, France

Appl. Sci. 2017, 7(5), 461; https://doi.org/10.3390/app7050461 - 30 Apr 2017

Cited by 7 | Viewed by 4407

Abstract

This paper deals with a preventive maintenance strategy optimization correlated to production for a manufacturing system made by several parallel machines under lease contract. In order to minimize the total cost of production and maintenance by reducing the production system interruptions due to [...] Read more.

This paper deals with a preventive maintenance strategy optimization correlated to production for a manufacturing system made by several parallel machines under lease contract. In order to minimize the total cost of production and maintenance by reducing the production system interruptions due to maintenance activities, a correlated group preventive maintenance policy is developed using the gravity center approach (GCA). The aim of this study is to determine an economical production plan and an optimal group preventive maintenance interval T_n at which all machines are maintained simultaneously. An analytical correlation between failure rate of machines and production level is considered and the impact of the preventive maintenance policy on the production plan is studied. Finally, the proposed maintenance policy GPM is compared with an individual simple strategy approach IPM in order to illustrate its efficiency. Full article

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15 pages, 7529 KiB

Open AccessFeature PaperArticle

Influence of the Origin of Polyamide 12 Powder on the Laser Sintering Process and Laser Sintered Parts

by Manfred Schmid^1,*, Rob Kleijnen¹, Marc Vetterli¹

and Konrad Wegener²

¹ Inspire, Innovation Center for Additive Manufacturing (icams), Lerchenfeldstrasse 3, St. Gallen 9014, Switzerland

² Department of Mechanical and Process Engineering, Swiss Institute of Technology (ETHZ), Tannenstrasse 3, Zürich 8093, Switzerland

Appl. Sci. 2017, 7(5), 462; https://doi.org/10.3390/app7050462 - 30 Apr 2017

Cited by 64 | Viewed by 9493

Abstract

Different features of polymer powders influence the process of laser sintering (LS) and the properties of LS-parts to a great extent. This study investigates important aspects of the “powder/process/part”-property relationships by comparing two polyamide 12 (PA12) powders commercially available for LS, with pronounced [...] Read more.

Different features of polymer powders influence the process of laser sintering (LS) and the properties of LS-parts to a great extent. This study investigates important aspects of the “powder/process/part”-property relationships by comparing two polyamide 12 (PA12) powders commercially available for LS, with pronounced powder characteristic differences (Duraform^® PA and Orgasol^® Invent Smooth). Due to the fact that the primary influence factor on polymer behaviour, the chemical structure of the polymer chain, is identical in this case, the impacts resulting from powder distribution, particle shape, thermal behaviour, and crystalline and molecular structure, can be studied in detail. It was shown that although both systems are PA12, completely different processing conditions must be applied to accomplish high-resolution parts. The reason for this was discovered by the different thermal behaviour based on the powder production and the resulting crystalline structure. Moreover, the parts built from Orgasol^® Invent Smooth unveil mechanical properties with pronounced anisotropy, caused from the high melt viscosity and termination of polymer chains. Further differences are seen in relation to the powder characteristics and other significant correlations could be revealed. For example, the study demonstrated how the particle morphology and shape impact the surface roughness of the parts. Full article

(This article belongs to the Special Issue Materials for 3D Printing)

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14 pages, 6949 KiB

Open AccessArticle

Experimental Studies on the Behavior of a Newly-Developed Type of Self-Insulating Concrete Masonry Shear Wall under in-Plane Cyclic Loading

by Abu-Bakre Abdelmoneim Elamin Mohamad^* and Zhongfan Chen

Key Laboratory of RC&PC Structures of Ministry of Education, Southeast University, Nanjing 210096, China

Appl. Sci. 2017, 7(5), 463; https://doi.org/10.3390/app7050463 - 30 Apr 2017

Cited by 4 | Viewed by 4953

Abstract

This study aimed to investigate the inelastic behavior of a newly-developed type of self-insulating concrete masonry shear wall (SCMSW) under in-plane cyclic loading. The new masonry system was made from concrete blocks with special configurations to provide a stronger bond between units than [...] Read more.

This study aimed to investigate the inelastic behavior of a newly-developed type of self-insulating concrete masonry shear wall (SCMSW) under in-plane cyclic loading. The new masonry system was made from concrete blocks with special configurations to provide a stronger bond between units than ordinary concrete masonry units. A total of six fully-grouted SCMSWs were prepared with different heights (1.59 to 5.78 m) and different vertical steel configurations. The developed masonry walls were tested under in-plane cyclic loading and different constant axial load ratios. In addition, the relationship between the amount of axial loading, the amount of the flexural reinforcement and the wall aspect ratios and the nonlinear hysteretic response of the SCMSW was evaluated. The results showed that the lateral load capacity of SCMSW increases with the amount of applied axial load and the amount of vertical reinforcement. However, the lateral load capacity decreases as the wall aspect ratio increases. The existence of the boundary elements at the SCMSW ends increases the ductility and the lateral load capacity. Generally, the SCMSW exhibited predominantly flexural behavior. These results agreed with those reported in previous research for walls constructed with ordinary units. Full article

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12 pages, 3230 KiB

Open AccessArticle

Failure Response of Simultaneously Pre-Stressed and Laser Irradiated Aluminum Alloys

by Mohsan Jelani¹

, Zewen Li^2,*, Zhonghua Shen^1,2 and Maryam Sardar¹

¹ School of Science, Nanjing University of Science and Technology, Nanjing 210094, China

² Advanced Launching Co-innovation Centre, Nanjing University of Science and Technology, Nanjing 210094, China

Appl. Sci. 2017, 7(5), 464; https://doi.org/10.3390/app7050464 - 29 Apr 2017

Cited by 11 | Viewed by 4996

Abstract

The failure response of aluminum alloys (Al-6061 and Al-7075) under the condition of simultaneously pre-stressing and laser heating was investigated. Specimens were subjected to predetermined preloading states and then irradiated by continuous wave fiber (Yb) laser. For all specimens, it was found that [...] Read more.

The failure response of aluminum alloys (Al-6061 and Al-7075) under the condition of simultaneously pre-stressing and laser heating was investigated. Specimens were subjected to predetermined preloading states and then irradiated by continuous wave fiber (Yb) laser. For all specimens, it was found that the yield stress decreased with increasing laser power density. This implies that the load-bearing capacity of the specimens reduced under increased thermal or tensile loading. Consequently, the specimen’s failure time was shortened by increasing either laser power density or preloaded speed. For Al-6061, a remarkable reduction in failure time by the increase of laser power density is found. However, for Al-7075, under higher preloaded speeds, comparatively smaller impact of laser power density on the failure time is reported. Moreover, for Al-6061, relatively a more non-uniform variation in the average failure time with the increase of laser power density or preloaded speed is observed. The failure mode of Al-6061 turned from brittle to ductile at higher laser power densities; whereas for Al-7075, it changed from quasi-brittle to ductile. At higher preloaded speeds, a greater degree of melting and ablation phenomenon can be seen due to relatively higher temperatures and higher heating rates. Full article

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16 pages, 4264 KiB

Open AccessArticle

Control of Corner Separation with Plasma Actuation in a High-Speed Compressor Cascade

by Haideng Zhang^1,2, Xianjun Yu^2,3,4,*

, Baojie Liu^2,3,4, Yun Wu¹ and Yinghong Li¹

¹ College of Aeronautical and Aerospace Engineering, Science and Technology on Plasma Dynamics Laboratory, Airforce Engineering University, Xi’an 710038, China

² School of Energy and Power Engineering, National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Beihang University, Beijing 100191, China

³ National Key Laboratory of Science & Technology on Aero-Engine Aero-Thermodynamics, Beihang University, Beijing 100191, China

⁴ Collaborative Innovation Center of Advanced Aero-Engine, Beihang University, Beijing 100191, China

Appl. Sci. 2017, 7(5), 465; https://doi.org/10.3390/app7050465 - 29 Apr 2017

Cited by 26 | Viewed by 5527

Abstract

The performances of modern highly loaded compressors are limited by the corner separations. Plasma actuation is a typical active flow control methodology, which has been proven to be capable of controlling the corner separations in low-speed compressor cascades. The main purpose of this [...] Read more.

The performances of modern highly loaded compressors are limited by the corner separations. Plasma actuation is a typical active flow control methodology, which has been proven to be capable of controlling the corner separations in low-speed compressor cascades. The main purpose of this paper is to uncover the flow control law and the mechanism of high-speed compressor cascade corner separation control with plasma actuations. The control effects of the suction surface as well as the endwall plasma actuations in suppressing the high-speed compressor cascade flow separations are investigated with numerical methods. The main flow structures within the high-speed compressor cascade corner separation and the development of the corresponding flow loss are investigated firstly. Next, the performances of plasma actuations in suppressing the high-speed compressor cascade corner separation are studied. At last, the mechanisms behind the control effects of the suction surface and the endwall plasma actuations are discussed. Both the suction surface and the endwall plasma actuations can improve the high-speed compressor cascade static pressure rise coefficient, while reducing the corresponding total pressure loss and blockage coefficients. The suction surface plasma actuation can suppress not only the high-speed compressor cascade corner separation vortex but also the airfoil separation, so, compared to the endwall plasma actuation, the suction surface plasma actuation is more efficient in reducing the total pressure loss of the high-speed compressor cascade. However, through suppressing the development of the passage vortex, the endwall plasma actuation is more efficient in reducing the flow blockage and improving the static pressure rise of the high-speed compressor cascade. Full article

(This article belongs to the Special Issue Active Flow Control Technologies for Energy and Propulsive Systems)

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18 pages, 8886 KiB

Open AccessArticle

Subsidence Evolution of the Leizhou Peninsula, China, Based on InSAR Observation from 1992 to 2010

by Yanan Du^1,2, Guangcai Feng^1,2,*, Xing Peng^1,2

and Zhiwei Li^1,2

¹ School of Geosciences and Info-Physics, Central South University, Changsha 410083, China

² *Correspondence: fredgps@csu.edu.cn

Appl. Sci. 2017, 7(5), 466; https://doi.org/10.3390/app7050466 - 29 Apr 2017

Cited by 19 | Viewed by 6710

Abstract

Over the past two decades, the Leizhou Peninsula has suffered from many geological hazards and great property losses caused by land subsidence. However, the absence of a deformation map of the whole peninsula has impeded the government in making the necessary decisions concerning [...] Read more.

Over the past two decades, the Leizhou Peninsula has suffered from many geological hazards and great property losses caused by land subsidence. However, the absence of a deformation map of the whole peninsula has impeded the government in making the necessary decisions concerning hazard prevention and mitigation. This study aims to provide the evolution of land deformation (subsidence and uplift) in the whole peninsula from 1992 to 2010. A modified stacking procedure is proposed to map the surface deformation with JERS, ENVISAT, and ALOS1 images. The map shows that the land subsidence mainly occurs along the coastline with a maximum velocity of 32 mm/year and in a wide range of inland arable lands with a velocity between 10 and 19 mm/year. Our study suggests that there is a direct correlation between the subsidence and the surface geology. Besides, the observed subsidence in urban areas, caused by groundwater overexploitation for domestic and industrial use, is moving from urban areas to suburban areas. In nonurban areas, groundwater extraction for aquaculture and arable land irrigation are the main reason for land subsidence, which accelerates saltwater intrusion and coastline erosion if regular surface deformation measurements and appropriate management measures are not taken. Full article

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24 pages, 2551 KiB

Open AccessArticle

Graph-Based Semi-Supervised Learning for Indoor Localization Using Crowdsourced Data

by Liye Zhang¹, Shahrokh Valaee², Yubin Xu^1,*, Lin Ma¹ and Farhang Vedadi²

¹ Communication Research Center, Harbin Institute of Technology, Harbin 150001, China

² Department of Electrical and Computer Engineering, University of Toronto, Toronto, ON M5S 3G4, Canada

Appl. Sci. 2017, 7(5), 467; https://doi.org/10.3390/app7050467 - 29 Apr 2017

Cited by 23 | Viewed by 4844

Abstract

Indoor positioning based on the received signal strength (RSS) of the WiFi signal has become the most popular solution for indoor localization. In order to realize the rapid deployment of indoor localization systems, solutions based on crowdsourcing have been proposed. However, compared to [...] Read more.

Indoor positioning based on the received signal strength (RSS) of the WiFi signal has become the most popular solution for indoor localization. In order to realize the rapid deployment of indoor localization systems, solutions based on crowdsourcing have been proposed. However, compared to conventional methods, lots of different devices are used in crowdsourcing system and less RSS values are collected by each device. Therefore, the crowdsourced RSS values are more erroneous and can result in significant localization errors. In order to eliminate the signal strength variations across diverse devices, the Linear Regression (LR) algorithm is proposed to solve the device diversity problem in crowdsourcing system. After obtaining the uniform RSS values, a graph-based semi-supervised learning (G-SSL) method is used to exploit the correlation between the RSS values at nearby locations to estimate an optimal RSS value at each location. As a result, the negative effect of the erroneous measurements could be mitigated. Since the AP locations need to be known in G-SSL algorithm, the Compressed Sensing (CS) method is applied to precisely estimate the location of the APs. Based on the location of the APs and a simple signal propagation model, the RSS difference between different locations is calculated and used as an additional constraint to improve the performance of G-SSL. Furthermore, to exploit the sparsity of the weights used in the G-SSL, we use the CS method to reconstruct these weights more accurately and make a further improvement on the performance of the G-SSL. Experimental results show improved results in terms of the smoothness of the radio map and the localization accuracy. Full article

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16 pages, 2657 KiB

Open AccessArticle

Optimal System Frequency Response Model and UFLS Schemes for a Small Receiving-End Power System after Islanding

by Deyou Yang^*

, Shiyu Liu and Guowei Cai

School of Electrical Engineering, Northeast Electric Power University, Jilin 132012, China

Appl. Sci. 2017, 7(5), 468; https://doi.org/10.3390/app7050468 - 2 May 2017

Cited by 5 | Viewed by 5046

Abstract

Large frequency deviations after islanding are exceedingly critical in small receiving-end power systems. The under-frequency load shedding (UFLS) scheme is an efficient protection step for preventing system black outs. It is very important to get an exact model to design the UFLS schemes. [...] Read more.

Large frequency deviations after islanding are exceedingly critical in small receiving-end power systems. The under-frequency load shedding (UFLS) scheme is an efficient protection step for preventing system black outs. It is very important to get an exact model to design the UFLS schemes. In this paper, an optimization model to achieve the system frequency response (SFR) model either from the full-scale power system or from test records was proposed. The optimized SFR model took into account the response of governors-prime movers and the dynamic characteristics of loads developed in the modern power system. Then the UFLS schemes were designed via the optimized SFR model and particle swarm optimization (PSO) method. The time-domain simulation with the actual small receiving-end power system was presented to investigate the validity of the presented model and the developed technique. Full article

(This article belongs to the Special Issue Distribution Power Systems)

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22 pages, 9840 KiB

Open AccessArticle

Multi-Objective Climb Path Optimization for Aircraft/Engine Integration Using Particle Swarm Optimization

by Aristeidis Antonakis^*, Theoklis Nikolaidis

and Pericles Pilidis

Propulsion Engineering Centre, School of Aerospace, Transport and Manufacturing, Cranfield University, Cranfield MK43 0AL, UK

Appl. Sci. 2017, 7(5), 469; https://doi.org/10.3390/app7050469 - 30 Apr 2017

Cited by 18 | Viewed by 7910

Abstract

In this article, a new multi-objective approach to the aircraft climb path optimization problem, based on the Particle Swarm Optimization algorithm, is introduced to be used for aircraft–engine integration studies. This considers a combination of a simulation with a traditional Energy approach, which [...] Read more.

In this article, a new multi-objective approach to the aircraft climb path optimization problem, based on the Particle Swarm Optimization algorithm, is introduced to be used for aircraft–engine integration studies. This considers a combination of a simulation with a traditional Energy approach, which incorporates, among others, the use of a proposed path-tracking scheme for guidance in the Altitude–Mach plane. The adoption of population-based solver serves to simplify case setup, allowing for direct interfaces between the optimizer and aircraft/engine performance codes. A two-level optimization scheme is employed and is shown to improve search performance compared to the basic PSO algorithm. The effectiveness of the proposed methodology is demonstrated in a hypothetic engine upgrade scenario for the F-4 aircraft considering the replacement of the aircraft’s J79 engine with the EJ200; a clear advantage of the EJ200-equipped configuration is unveiled, resulting, on average, in 15% faster climbs with 20% less fuel. Full article

(This article belongs to the Special Issue Gas Turbines Propulsion and Power)

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13 pages, 10428 KiB

Open AccessArticle

Four-Dimensional Thermal Analysis of 888 nm Pumped Nd:YVO₄ Dual-Rod Acousto-Optic Q-Switched Laser

by Yijie Shen^†

, Wenqi Zhang^†, Mali Gong^*, Yuan Meng

, Yunbin Wang and Xing Fu

¹ State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China

^† These authors contributed equally to this work.

Appl. Sci. 2017, 7(5), 470; https://doi.org/10.3390/app7050470 - 8 May 2017

Cited by 13 | Viewed by 6569

Abstract

A theoretical analysis upon the four-dimensional (4D) spatio-temporal temperature dependent dynamics of 888 nm pumped Nd:YVO

_{4}

dual-rod laser is established, which is valid in both continuous-wave (CW) and acousto-optic (AO) Q-switched pulse lasers conditions. Our model can accurately solve the 4D thermal [...] Read more.

A theoretical analysis upon the four-dimensional (4D) spatio-temporal temperature dependent dynamics of 888 nm pumped Nd:YVO

_{4}

dual-rod laser is established, which is valid in both continuous-wave (CW) and acousto-optic (AO) Q-switched pulse lasers conditions. Our model can accurately solve the 4D thermal generation and temperature evolution not only in the steady Q-switched state, but also in the first few unstable giant or dwarf pulses region. Factors including ground state depletion (GSD), energy transfer upconversion (ETU), fluorescence branching ratios, temperature-dependent cross sections and nonradiative relaxations processes are comprehensively considered for precisely estimating thermal effects, valid in both the steady pulse region and the unstable region at the beginning. Moreover, temporal and spatial temperature profiles and their coupling effect on output properties at different repetition-rates are discussed. Experiments of high-power high-repetition-rate 888 nm end-pumped Nd:YVO

_{4}

dual-rod CW and AO Q-switched lasers are also firstly presented and the experimental results enjoy good consistency with our theory. Full article

(This article belongs to the Section Optics and Lasers)

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15 pages, 804 KiB

Open AccessArticle

An Improved Differential Quadrature Time Element Method

by Mingbo Qin¹, Yufeng Xing^1,*

and Jing Guo²

¹ Institute of Solid Mechanics, Beihang University, No. 37, Xueyuan Road, Haidian District, Beijing 100191, China

² Science and Technology on Reliability and Environment Engineering Laboratory, Beijng Institute of Structure and Environment Engineering, No. 1, Dahongmen Road, Fengtai District, Beijing 100076, China

Appl. Sci. 2017, 7(5), 471; https://doi.org/10.3390/app7050471 - 3 May 2017

Cited by 7 | Viewed by 4883

Abstract

A Differential Quadrature Time Element Method (DQTEM) was proposed by the author and co-worker, its drawback is the need of larger storage capacity since the dimension of the coefficients matrix for solution is the product of both spatial degrees of freedom and temporal [...] Read more.

A Differential Quadrature Time Element Method (DQTEM) was proposed by the author and co-worker, its drawback is the need of larger storage capacity since the dimension of the coefficients matrix for solution is the product of both spatial degrees of freedom and temporal degrees of freedom. To solve this problem, an improved DQTEM is developed in this work, in which the differential quadrature method is used to discretize both spatial and time domains, sequentially, and the dimension of the coefficients matrix is greatly reduced without losing solution accuracy. Theoretical studies demonstrate the improved DQTEM features superiorities including higher-order accuracy, adequate stability and symplectic characteristics. The improvement of DQTEM is validated by extensive comparisons of the present DQTEM with the original DQTEM. Full article

(This article belongs to the Special Issue Applications of Generalized Differential and Integral Quadrature Methods)

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21 pages, 6886 KiB

Open AccessFeature PaperReview

Dental Applications of Optical Coherence Tomography (OCT) in Cariology

by Hartmut Schneider^*, Kyung-Jin Park, Matthias Häfer, Claudia Rüger, Gerhard Schmalz, Felix Krause, Jana Schmidt, Dirk Ziebolz

and Rainer Haak

Department of Cariology, Endodontology and Periodontology, University of Leipzig, Liebigstraße 12, 04103 Leipzig, Germany

Appl. Sci. 2017, 7(5), 472; https://doi.org/10.3390/app7050472 - 3 May 2017

Cited by 70 | Viewed by 20214

Abstract

Across all medical disciplines, therapeutic interventions are based on previously acquired diagnostic information. In cariology, which includes the detection and assessment of the disease “caries” and its lesions, as well as non-invasive to invasive treatment and caries prevention, visual inspection and radiology are [...] Read more.

Across all medical disciplines, therapeutic interventions are based on previously acquired diagnostic information. In cariology, which includes the detection and assessment of the disease “caries” and its lesions, as well as non-invasive to invasive treatment and caries prevention, visual inspection and radiology are routinely used as diagnostic tools. However, the specificity and sensitivity of these standard methods are still unsatisfactory and the detection of defects is often afflicted with a time delay. Numerous novel methods have been developed to improve the unsatisfactory diagnostic possibilities in this specialized medical field. These newer techniques have not yet found widespread acceptance in clinical practice, which might be explained by the generated numerical or color-coded output data that are not self-explanatory. With optical coherence tomography (OCT), an innovative image-based technique has become available that has considerable potential in supporting the routine assessment of teeth in the future. The received cross-sectional images are easy to interpret and can be processed. In recent years, numerous applications of OCT have been evaluated in cariology beginning with the diagnosis of different defects up to restoration assessment and their monitoring, or the visualization of individual treatment steps. Based on selected examples, this overview outlines the possibilities and limitations of this technique in cariology and restorative dentistry, which pertain to the most clinical relevant fields of dentistry. Full article

(This article belongs to the Special Issue Development and Application of Optical Coherence Tomography (OCT))

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11 pages, 2980 KiB

Open AccessArticle

Single Mode Air-Clad Single Crystal Sapphire Optical Fiber

by Cary Hill^1,*, Dan Homa¹

, Zhihao Yu², Yujie Cheng¹, Bo Liu², Anbo Wang² and Gary Pickrell¹

¹ Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24061, USA

² Center for Photonics Technology, Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, VA 24061, USA

Appl. Sci. 2017, 7(5), 473; https://doi.org/10.3390/app7050473 - 3 May 2017

Cited by 33 | Viewed by 7445

Abstract

The observation of single mode propagation in an air-clad single crystal sapphire optical fiber at wavelengths at and above 783 nm is presented for the first time. A high-temperature wet acid etching method was used to reduce the diameter of a 10 cm [...] Read more.

The observation of single mode propagation in an air-clad single crystal sapphire optical fiber at wavelengths at and above 783 nm is presented for the first time. A high-temperature wet acid etching method was used to reduce the diameter of a 10 cm length of commercially-sourced sapphire fiber from 125 micrometers to 6.5 micrometers, and far-field imaging provided modal information at intervals as the fiber diameter decreased. Modal volume was shown to decrease with decreasing diameter, and single mode behavior was observed at the minimum diameter achieved. While weakly-guiding approximations are generally inaccurate for low modal volume optical fiber with high core-cladding refractive index disparity, consistency between these approximations and experimental results was observed when the effective numerical aperture was measured and substituted for the theoretical numerical aperture in weakly-guiding approximation calculations. With the demonstration of very low modal volume in sapphire at fiber diameters much larger than anticipated by legacy calculations, the resolution of sapphire fiber distributed sensors may be increased and other sensing schemes requiring very low modal volume, such as fiber Bragg gratings, may be realized in extreme environment applications. Full article

(This article belongs to the Special Issue Distributed Optical Fiber Sensors)

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34 pages, 7446 KiB

Open AccessFeature PaperReview

Polarization Sensitive Optical Coherence Tomography: A Review of Technology and Applications

by Bernhard Baumann

Medical University of Vienna, Center for Medical Physics and Biomedical Engineering, Waehringer Guertel 18-20, 4L, 1090 Vienna, Austria

Appl. Sci. 2017, 7(5), 474; https://doi.org/10.3390/app7050474 - 4 May 2017

Cited by 141 | Viewed by 21809

Abstract

Polarization sensitive optical coherence tomography (PS-OCT) is an imaging technique based on light scattering. PS-OCT performs rapid two- and three-dimensional imaging of transparent and translucent samples with micrometer scale resolution. PS-OCT provides image contrast based on the polarization state of backscattered light and [...] Read more.

Polarization sensitive optical coherence tomography (PS-OCT) is an imaging technique based on light scattering. PS-OCT performs rapid two- and three-dimensional imaging of transparent and translucent samples with micrometer scale resolution. PS-OCT provides image contrast based on the polarization state of backscattered light and has been applied in many biomedical fields as well as in non-medical fields. Thereby, the polarimetric approach enabled imaging with enhanced contrast compared to standard OCT and the quantitative assessment of sample polarization properties. In this article, the basic methodological principles, the state of the art of PS-OCT technologies, and important applications of the technique are reviewed in a concise yet comprehensive way. Full article

(This article belongs to the Special Issue Development and Application of Optical Coherence Tomography (OCT))

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13 pages, 4367 KiB

Open AccessArticle

A Fast and Cost-Effective Detection of Melamine by Surface Enhanced Raman Spectroscopy Using a Novel Hydrogen Bonding-Assisted Supramolecular Matrix and Gold-Coated Magnetic Nanoparticles

by Jing Neng, Jiayuan Tan, Kan Jia and Peilong Sun^*

Department of Food Science and Technology, Zhejiang University of Technology, Hangzhou 310014, China

Appl. Sci. 2017, 7(5), 475; https://doi.org/10.3390/app7050475 - 3 May 2017

Cited by 18 | Viewed by 7841

Abstract

A fast and cost-effective melamine detection approach has been developed based on surface enhanced Raman spectroscopy (SERS) using a novel hydrogen bonding-assisted supramolecular matrix. The detection utilizes Fe₃O₄/Au magnetic nanoparticles coated with 5-aminoorotic acid (AOA) as a SERS active [...] Read more.

A fast and cost-effective melamine detection approach has been developed based on surface enhanced Raman spectroscopy (SERS) using a novel hydrogen bonding-assisted supramolecular matrix. The detection utilizes Fe₃O₄/Au magnetic nanoparticles coated with 5-aminoorotic acid (AOA) as a SERS active substrate (Fe₃O₄/Au–AOA), and Rhodamine B (RhB) conjugated AOA as a Raman reporter (AOA–RhB). Upon mixing the reagents with melamine, a supramolecular complex [Fe₃O₄/Au–AOA•••melamine•••AOA–RhB] was formed due to the strong multiple hydrogen bonding interactions between AOA and melamine. The complex was separated and concentrated to a pellet by an external magnet and used as a supramolecular matrix for the melamine detection. Laser excitation of the complex pellet produced a strong SERS signal diagnostic for RhB. The logarithmic intensity of the characteristic RhB peaks was found to be proportional to the concentration of melamine with a limit of detection of 2.5 µg/mL and a detection linearity range of 2.5~15.0 µg/mL in milk. As Fe₃O₄ nanoparticles and AOA are thousands of times less expensive than the monoclonal antibody used in a traditional sandwich immunoassay, the current assay drastically cut down the cost of melamine detection. The current approach affords promise as a biosensor platform that cuts down sample pre-treatment steps and measurement expense. Full article

(This article belongs to the Special Issue Biological Applications of Magnetic Nanoparticles)

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13 pages, 3788 KiB

Open AccessArticle

Vibration Control of a Power Transmission Tower with Pounding Tuned Mass Damper under Multi-Component Seismic Excitations

by Li Tian¹, Kunjie Rong¹, Peng Zhang² and Yuping Liu^1,*

¹ School of Civil Engineering, Shandong University, Jinan 250061, Shandong Province, China

² Transportation Equipment and Ocean Engineering College, Dalian Maritime University, Dalian 116026, Liaoning Province, China

Appl. Sci. 2017, 7(5), 477; https://doi.org/10.3390/app7050477 - 5 May 2017

Cited by 42 | Viewed by 8615

Abstract

In this paper, the two-dimensional vibration controls of a power transmission tower with a pounding tuned mass damper (PTMD) under multi-component seismic excitations are analyzed. A three-dimensional finite element model of a practical power transmission tower is established in ABAQUS (Dassasult Simulia Company, [...] Read more.

In this paper, the two-dimensional vibration controls of a power transmission tower with a pounding tuned mass damper (PTMD) under multi-component seismic excitations are analyzed. A three-dimensional finite element model of a practical power transmission tower is established in ABAQUS (Dassasult Simulia Company, Providence, RI, USA). The TMD (tuned mass damper) and PTMD are simulated by the finite element method. The response of the transmission tower with TMD and PTMD are analyzed, respectively. To achieve optimal design, the influence of the mass ratio, ground motion intensity, gap, and incident angle of seismic ground motion are investigated, respectively. The results show that the PTMD is very effective in reducing the vibration of the transmission tower in the longitudinal and transverse directions. The reduction ratio increases with the increase of the mass ratio. The ground motion intensity and gap have no obvious influence on the reduction ratio. However, the incident angle has a significant influence on the reduction ratio. Full article

(This article belongs to the Special Issue Development and Application of Nonlinear Dissipative Device in Structural Vibration Control)

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16 pages, 3775 KiB

Open AccessArticle

A Novel Technique for Designing High Power Semiconductor Optical Amplifier (SOA)-Based Tunable Fiber Compound-Ring Lasers Using Low Power Optical Components

by Muhammad A. Ummy^1,*, Simeon Bikorimana² and Roger Dorsinville²

¹ New York City College of Technology, City University of New York, New York, NY 11201, USA

² The City College of New York, City University of New York, New York, NY 10031, USA

Appl. Sci. 2017, 7(5), 478; https://doi.org/10.3390/app7050478 - 5 May 2017

Cited by 3 | Viewed by 5625

Abstract

A simple, stable and inexpensive dual-output port widely tunable semiconductor optical amplifier (SOA)-based fiber compound-ring laser structure is demonstrated. This unique nested ring cavity enables high optical power to split into different branches where amplification and wavelength selection are achieved by using low-power [...] Read more.

A simple, stable and inexpensive dual-output port widely tunable semiconductor optical amplifier (SOA)-based fiber compound-ring laser structure is demonstrated. This unique nested ring cavity enables high optical power to split into different branches where amplification and wavelength selection are achieved by using low-power SOAs and a tunable filter. Furthermore, two Sagnac loop mirrors, which are spliced at the two ends of the compound-ring cavity not only serve as variable reflectors but also channel the optical energy back to the same port without using any high optical power combiner. We propose and discuss how the demonstrated fiber compound-ring laser structure can be extended in order to achieve a high power fiber laser source by using low power optical components, such as N × N couplers and (N > 1) number of SOAs. A coherent beam-combining efficiency of over 98% for two parallel nested fiber ring resonators is achieved over the C-band tuning range of 30 nm. Optical signal-to-noise ratio (OSNR) of +45 dB, and optical power fluctuation of less than ±0.02 dB are measured over three hours at room temperature. Full article

(This article belongs to the Section Optics and Lasers)

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11 pages, 3230 KiB

Open AccessFeature PaperArticle

Construction and Commissioning of PAL-XFEL Facility

by In Soo Ko^*, Heung-Sik Kang, Hoon Heo, Changbum Kim, Gyujin Kim, Chang-Ki Min, Haeryong Yang, Soung Youl Baek, Hyo-Jin Choi, Geonyeong Mun, Byoung Ryul Park, Young Jin Suh, Dong Cheol Shin, Jinyul Hu, Juho Hong, Seonghoon Jung, Sang-Hee Kim, KwangHoon Kim, Donghyun Na, Soung Soo Park, Yong Jung Park, Young Gyu Jung, Seong Hun Jeong, Hong Gi Lee, Sangbong Lee, Sojeong Lee, Bonggi Oh, Hyung Suck Suh, Jang-Hui Han, Min Ho Kim, Nam-Suk Jung, Young-Chan Kim, Mong-Soo Lee, Bong-Ho Lee, Chi-Won Sung, Ik-Su Mok, Jung-Moo Yang, Yong Woon Parc, Woul-Woo Lee, Chae-Soon Lee, Hocheol Shin, Ji Hwa Kim, Yongsam Kim, Jae Hyuk Lee, Sang-Youn Park, Jangwoo Kim

, Jaeku Park, Intae Eom, Seungyu Rah, Sunam Kim, Ki Hyun Nam, Jaehyun Park, Jaehun Park, Sangsoo Kim, Soonnam Kwon, Ran An, Sang Han Park, Kyung Sook Kim, Hyojung Hyun, Seung Nam Kim, Seonghan Kim, Chung-Jong Yu, Bong-Soo Kim, Tai-Hee Kang, Kwang-Woo Kim, Seung-Hwan Kim, Hee-Seock Lee, Heung-Soo Lee, Ki-Hyeon Park, Tae-Yeong Koo, Dong-Eon Kim and Ki Bong Lee Show full author list Hide full author list

Pohang Accelerator Laboratory, POSTECH, Pohang 37673, Korea

Appl. Sci. 2017, 7(5), 479; https://doi.org/10.3390/app7050479 - 17 May 2017

Cited by 124 | Viewed by 12034

Abstract

The construction of Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL), a 0.1-nm hard X-ray free-electron laser (FEL) facility based on a 10-GeV S-band linear accelerator (LINAC), is achieved in Pohang, Korea by the end of 2016. The construction of the 1.11 km-long building [...] Read more.

The construction of Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL), a 0.1-nm hard X-ray free-electron laser (FEL) facility based on a 10-GeV S-band linear accelerator (LINAC), is achieved in Pohang, Korea by the end of 2016. The construction of the 1.11 km-long building was completed by the end of 2014, and the installation of the 10-GeV LINAC and undulators started in January 2015. The installation of the 10-GeV LINAC, together with the undulators and beamlines, was completed by the end of 2015. The commissioning began in April 2016, and the first lasing of the hard X-ray FEL line was achieved on 14 June 2016. The progress of the PAL-XFEL construction and its commission are reported here. Full article

(This article belongs to the Special Issue X-Ray Free-Electron Laser)

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25 pages, 5306 KiB

Open AccessArticle

A Study of the Transient Response of Duct Junctions: Measurements and Gas-Dynamic Modeling with a Staggered Mesh Finite Volume Approach

by Antonio J. Torregrosa^*

, Alberto Broatch, Luis M. García-Cuevas

and Manuel Hernández

CMT–Motores Térmicos, Universitat Politècnica de València, 46022 Valencia, Spain

Appl. Sci. 2017, 7(5), 480; https://doi.org/10.3390/app7050480 - 8 May 2017

Cited by 2 | Viewed by 5063

Abstract

Duct junctions play a major role in the operation and design of most piping systems. The objective of this paper is to establish the potential of a staggered mesh finite volume model as a way to improve the description of the effect of [...] Read more.

Duct junctions play a major role in the operation and design of most piping systems. The objective of this paper is to establish the potential of a staggered mesh finite volume model as a way to improve the description of the effect of simple duct junctions on an otherwise one-dimensional flow system, such as the intake or exhaust of an internal combustion engine. Specific experiments have been performed in which different junctions have been characterized as a multi-port, and that have provided precise and reliable results on the propagation of pressure pulses across junctions. The results obtained have been compared to simulations performed with a staggered mesh finite volume method with different flux limiters and different meshes and, as a reference, have also been compared with the results of a more conventional pressure loss-based model. The results indicate that the staggered mesh finite volume model provides a closer description of wave dynamics, even if further work is needed to establish the optimal calculation settings. Full article

(This article belongs to the Special Issue Internal Combustion Engines (ICE) for Ground Transport)

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13 pages, 3168 KiB

Open AccessArticle

Variable Pole Pitch Electromagnetic Propulsion with Ladder-Slot-Secondary Double-Sided Linear Induction Motors

by Jun Di^*, Yu Fan, Yajing Liu, Sijia Liu and Yulong Zhu

School of Electrical Engineering, Beijing Jiaotong University, Beijing 100044, China

Appl. Sci. 2017, 7(5), 481; https://doi.org/10.3390/app7050481 - 6 May 2017

Cited by 5 | Viewed by 6533

Abstract

In this paper, we propose a novel variable pole pitch (VPP) electromagnetic (EM) propulsion technique using a series of ladder-slot-secondary double-sided linear induction motors (LS-secondary DLIMs). An equivalent circuit is developed for the LS-secondary DLIM, which considers the distribution of the eddy current [...] Read more.

In this paper, we propose a novel variable pole pitch (VPP) electromagnetic (EM) propulsion technique using a series of ladder-slot-secondary double-sided linear induction motors (LS-secondary DLIMs). An equivalent circuit is developed for the LS-secondary DLIM, which considers the distribution of the eddy current in the ladders and the end effect. This equivalent circuit forms the basis for the subsequent design, numerical analysis, and optimization. The primary purpose of the VPP EM propulsion system is to address several obstacles encountered in high-speed large-thrust applications of LIMs, such as power factor improvement, optimization considering supply frequency constraint and operating kinetics, etc. The equivalent circuit of the LS-secondary DLIM, i.e., the theoretical foundation of the VPP EM propulsion, has been validated via simulation and experimentation on a small-scale platform, which proves that the numerical analysis of the VPP EM propulsion is effective. Full article

(This article belongs to the Section Energy Science and Technology)

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31 pages, 11369 KiB

Open AccessArticle

Development of Height Indicators using Omnidirectional Images and Global Appearance Descriptors

by Francisco Amorós^†, Luis Payá^*,†

, Mónica Ballesta^†

and Oscar Reinoso^†

¹ Miguel Hernandez University, Department of Systems Engineering and Automation, Avda. de la Universidad s/n. Ed. Innova. 03202, Elche (Alicante), Spain

^† These authors contributed equally to this work.

Appl. Sci. 2017, 7(5), 482; https://doi.org/10.3390/app7050482 - 6 May 2017

Cited by 1 | Viewed by 3346

Abstract

Nowadays, mobile robots have become a useful tool that permits solving a wide range of applications. Their importance lies in their ability to move autonomously through unknown environments and to adapt to changing conditions. To this end, the robot must be able to [...] Read more.

Nowadays, mobile robots have become a useful tool that permits solving a wide range of applications. Their importance lies in their ability to move autonomously through unknown environments and to adapt to changing conditions. To this end, the robot must be able to build a model of the environment and to estimate its position using the information captured by the different sensors it may be equipped with. Omnidirectional vision sensors have become a robust option thanks to the richness of the data they capture. These data must be analysed to extract relevant information that permits estimating the position of the robot taking into account the number of degrees of freedom it has. In this work, several methods to estimate the relative height of a mobile robot are proposed and evaluated. The framework we present is based on the global appearance of the scenes, which has emerged as an efficient and robust alternative comparing to methods based on local features. All the algorithms have been tested with some sets of images captured under real working conditions in several indoor and outdoor spaces. The results prove that global appearance descriptors provide a feasible alternative to estimate topologically the relative altitude of the robot. Full article

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17 pages, 1518 KiB

Open AccessFeature PaperArticle

Late Reverberation Synthesis Using Filtered Velvet Noise

by Vesa Välimäki^*

, Bo Holm-Rasmussen^‡, Benoit Alary and Heidi-Maria Lehtonen^‡

¹ Acoustics Lab, Department of Signal Processing and Acoustics, Aalto University, 02150 Espoo, Finland

^‡ Current addresses: Bo Holm-Rasmussen—The Royal Danish Academy of Fine Arts, Laboratory for Sound, 1050 Copenhagen, Denmark. Heidi-Maria Lehtonen—Dolby Sweden, 11330 Stockholm, Sweden.

Appl. Sci. 2017, 7(5), 483; https://doi.org/10.3390/app7050483 - 6 May 2017

Cited by 34 | Viewed by 7568

Abstract

This paper discusses the modeling of the late part of a room impulse response by dividing it into short segments and approximating each one as a filtered random sequence. The filters and their associated gain account for the spectral shape and decay of [...] Read more.

This paper discusses the modeling of the late part of a room impulse response by dividing it into short segments and approximating each one as a filtered random sequence. The filters and their associated gain account for the spectral shape and decay of the overall response. The noise segments are realized with velvet noise, which is sparse pseudo-random noise. The proposed approach leads to a parametric representation and computationally efficient artificial reverberation, since convolution with velvet noise reduces to a multiplication-free sparse sum. Cascading of the differential coloration filters is proposed to further reduce the computational cost. A subjective test shows that the resulting approximation of the late reverberation often leads to a noticeable difference in comparison to the original impulse response, especially with transient sounds, but the difference is minor. The proposed method is very efficient in terms of real-time computational cost and memory storage. The proposed method will be useful for spatial audio applications. Full article

(This article belongs to the Special Issue Spatial Audio)

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13 pages, 5214 KiB

Open AccessArticle

Numerical Simulation of Red Blood Cell-Induced Platelet Transport in Saccular Aneurysms

by Wei-Tao Wu¹, Yubai Li², Nadine Aubry³, Mehrdad Massoudi⁴ and James F. Antaki^1,*

¹ Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA

² Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, State College, PA 16803, USA

³ Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA 02115

⁴ U.S. Department of Energy, National Energy Technology Laboratory (NETL), Pittsburgh, PA 15236, USA

Appl. Sci. 2017, 7(5), 484; https://doi.org/10.3390/app7050484 - 6 May 2017

Cited by 13 | Viewed by 6169

Abstract

We present a numerical simulation of blood flow in two aneurysmal vessels. Using a multicomponent continuum approach, called mixture theory, the velocity fields and spatial distribution of the red blood cells (RBCs) and the plasma are predicted. Platelet migration is described by a [...] Read more.

We present a numerical simulation of blood flow in two aneurysmal vessels. Using a multicomponent continuum approach, called mixture theory, the velocity fields and spatial distribution of the red blood cells (RBCs) and the plasma are predicted. Platelet migration is described by a convection-diffusion equation, coupled to the RBC concentration field. The model is applied to study a two-dimensional straight vessel and multiple two-dimensional aneurysm vessels with different neck sizes. The model accurately predicts the enrichment of the platelets near the wall in the straight vessel, agreeing with the experimental measurement quantitatively. The numerical results also show that the near-wall enrichment of the platelets in the parent vessel highly influences the platelet concentration within the aneurysm. The results also indicate that the platelet concentration within the aneurysm increases with Reynolds number and decreases with a smaller neck size. This might have significance on the formation of thrombus (blood clot) within the aneurysm, which in turn may have a protective effect on preventing ruptures. Based on the success with the problems studied, we believe the current model can be a useful tool for analyzing the blood flow and platelets transport within patient specific aneurysms in the future. Full article

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13 pages, 8054 KiB

Open AccessArticle

Optimization of Hybrid Ultrasonic Frequency Pulsed VP-GTAW Process Parameters on Tensile Properties of AA 5456 Alloy

by Yipeng Wang^1,2, Bojin Qi^1,2, Baoqiang Cong^1,2,* and Mingxuan Yang^1,2

¹ Department of Materials Processing, Beijing University of Aeronautics and Astronautics, Beijing 100191, China

² MIIT Key Laboratory of Aeronautics Intelligent Manufacturing, Beijing 100191, China

Appl. Sci. 2017, 7(5), 485; https://doi.org/10.3390/app7050485 - 8 May 2017

Cited by 11 | Viewed by 6033

Abstract

Tensile properties optimization of AA 5456 aluminum alloy was carried out with hybrid ultrasonic frequency pulsed variable polarity gas tungsten arc wending (HPVP-GTAW). An orthogonal method was employed to conduct the experiments, and the tensile properties of AA 5456 aluminum alloy welded joints [...] Read more.

Tensile properties optimization of AA 5456 aluminum alloy was carried out with hybrid ultrasonic frequency pulsed variable polarity gas tungsten arc wending (HPVP-GTAW). An orthogonal method was employed to conduct the experiments, and the tensile properties of AA 5456 aluminum alloy welded joints were measured and analyzed. Regression models were developed based on the least square estimation by taking tensile strength, yield strength, percent elongation, and ratio of reduction in area as response functions of variable polarity frequency f_L, pulse frequency f_H and a dimensionless parameter ψ, which were calculated by background current I_b, peak current I_p, and pulse duration δ, respectively. The developed regression equations were checked for validity by coefficient of correlation r² and confirmatory experiments. Optimum parameters of HPVP-GTAW were achieved through the discussion on response surfaces and contour plots drawn using the regression equations. Full article

(This article belongs to the Special Issue Gas Tungsten Arc Welding)

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8 pages, 533 KiB

Open AccessArticle

Relationship between Amount of Daily Movement Measured by a Triaxial Accelerometer and Motor Symptoms in Patients with Parkinson’s Disease

by Hiroo Terashi^1,*, Hiroshi Mitoma², Mitsuru Yoneyama³

and Hitoshi Aizawa¹

¹ Department of Neurology, Tokyo Medical University, 6-7-1 Nishishinjuku, Shinjuku-ku, Tokyo 160-0023, Japan

² Medical Education Promotion Center, Tokyo Medical University, Tokyo 160-0023, Japan

³ MCHC R&D Synergy Center, Inc., Yokohama 227-0033, Japan

Appl. Sci. 2017, 7(5), 486; https://doi.org/10.3390/app7050486 - 9 May 2017

Cited by 6 | Viewed by 4243

Abstract

The aim of this study was to analyze the association between the amount of daily movement measured with a triaxial accelerometer (MIMAMORI-Gait) and motor symptoms in patients with Parkinson’s disease (PD). The subjects were 50 consecutive patients with untreated PD free of dementia. [...] Read more.

The aim of this study was to analyze the association between the amount of daily movement measured with a triaxial accelerometer (MIMAMORI-Gait) and motor symptoms in patients with Parkinson’s disease (PD). The subjects were 50 consecutive patients with untreated PD free of dementia. The amount of overall movement over 24 h was measured with the portable MIMAMORI-Gait device and its association with the modified Hoehn and Yahr stage and UPDRS part II and III scores was analyzed. In patients with PD, the amount of overall movement measured with MIMAMORI-Gait was significantly associated with the UPDRS part II score (β = −0.506, p < 0.001) and part III score (β = −0.347, p = 0.010), but not with the modified Hoehn and Yahr stage. The amount of overall movement measured with MIMAMORI-Gait can potentially be used for evaluation of motor symptoms and ADL in PD patients. Full article

(This article belongs to the Special Issue Application of Signal Processing Methods for Systematic Analysis of Physiological Health)

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18 pages, 1894 KiB

Open AccessArticle

Decision Optimization for Power Grid Operating Conditions with High- and Low-Voltage Parallel Loops

by Dong Yang¹, Kang Zhao¹

, Hao Tian² and Yutian Liu^2,*

¹ State Grid Shandong Electric Power Research Institute, Jinan 250003, China

² Key Laboratory of Power System Intelligent Dispatch and Control of Ministry of Education, Shandong University, Jinan 250061, China

Appl. Sci. 2017, 7(5), 487; https://doi.org/10.3390/app7050487 - 9 May 2017

Cited by 4 | Viewed by 5481

Abstract

With the development of higher-voltage power grids, the high- and low-voltage parallel loops are emerging, which lead to energy losses and even threaten the security and stability of power systems. The multi-infeed high-voltage direct current (HVDC) configurations widely appearing in AC/DC interconnected power [...] Read more.

With the development of higher-voltage power grids, the high- and low-voltage parallel loops are emerging, which lead to energy losses and even threaten the security and stability of power systems. The multi-infeed high-voltage direct current (HVDC) configurations widely appearing in AC/DC interconnected power systems make this situation even worse. Aimed at energy saving and system security, a decision optimization method for power grid operating conditions with high- and low-voltage parallel loops is proposed in this paper. Firstly, considering hub substation distribution and power grid structure, parallel loop opening schemes are generated with GN (Girvan-Newman) algorithms. Then, candidate opening schemes are preliminarily selected from all these generated schemes based on a filtering index. Finally, with the influence on power system security, stability and operation economy in consideration, an evaluation model for candidate opening schemes is founded based on analytic hierarchy process (AHP). And a fuzzy evaluation algorithm is used to find the optimal scheme. Simulation results of a New England 39-bus system and an actual power system validate the effectiveness and superiority of this proposed method. Full article

(This article belongs to the Special Issue Energy Saving)

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14 pages, 2149 KiB

Open AccessFeature PaperArticle

Design Optimization of a District Heating Network Expansion, a Case Study for the Town of Kiruna

by Mattias Vesterlund^* and Andrea Toffolo^*

Division of Energy Science, Energy Engineering, Department of Engineering Science and Mathematics, Luleå University of Technology, 971 87 Luleå, Sweden

Appl. Sci. 2017, 7(5), 488; https://doi.org/10.3390/app7050488 - 10 May 2017

Cited by 29 | Viewed by 7738

Abstract

The urbanization of new areas beyond the existing perimeter of a town implies the expansion of several infrastructures, including the district heating network. The main variables involved in the design of the district heating network expansion are the layout of the new pipes, [...] Read more.

The urbanization of new areas beyond the existing perimeter of a town implies the expansion of several infrastructures, including the district heating network. The main variables involved in the design of the district heating network expansion are the layout of the new pipes, their diameters, and the capacity of the new heat production sites that are required to satisfy the increased demand of room heating and hot tap water. In this paper, a multi-objective evolutionary algorithm is applied to the minimization of the costs related to the expansion of the district heating network of the town of Kiruna, in northern Sweden. The results show that the spectrum of the optimal design compromises between investment costs for the new pipes and the new heat generation site on one side, and operating costs due to overall fuel consumption and pumping power in the network on the other. The presented methodology is a tool meant for the decision makers in the company who own the district heating network, to evaluate all the possible best design alternatives before making a decision. Full article

(This article belongs to the Special Issue Simulation, Analysis, Optimization and New Challenges of District Heating and Cooling Networks)

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12 pages, 8459 KiB

Open AccessArticle

Mechanical Performance Monitoring for Prestressed Concrete Piles Used in a Newly-Built High-Piled Wharf in a Harbor with Fiber Bragg Grating Sensor Technology When Pile Driving

by Hongbiao Liu¹, Qiang Zhang¹ and Liang Ren^2,*

¹ Tianjin Research Institute for Water Transport Engineering, National Engineering Laboratory for Port Hydraulic Construction Technology, Tianjin 300456, China

² Faculty of Infrastructure Engineering, Dalian University of Technology, Dalian 116024, China

Appl. Sci. 2017, 7(5), 489; https://doi.org/10.3390/app7050489 - 10 May 2017

Cited by 6 | Viewed by 5547

Abstract

Mechanical performance monitoring of civil infrastructure using fiber Bragg grating (FBG) sensors has received significant public attention in recent years. However, there is currently little research on the mechanical performance monitoring of piles used in high-piled wharfs in coastal ports during pile driving [...] Read more.

Mechanical performance monitoring of civil infrastructure using fiber Bragg grating (FBG) sensors has received significant public attention in recent years. However, there is currently little research on the mechanical performance monitoring of piles used in high-piled wharfs in coastal ports during pile driving using the FBG sensor technique. Based on the properties of precast prestressed concrete piles used in high-piled wharfs in coastal ports and servicing seawater environments, and the benefits of FBG sensors, the mechanical performance monitoring for precast prestressed concrete piles used in a newly-built high-piled wharf in the Tianjin Port of China is devised and deployed with the FBG sensor technique. To conduct performance monitoring of the precast prestressed concrete pile, a state-of-the-art FBG strain sensor, which is less thermosensitive and does not require temperature compensation, was used to monitor the strain status of different locations of the pile. In one pile, three of this kind of strain sensor were set near the head, middle and tip of the pile, and one FBG angle sensor was set near the head of the pile to measure the dip angle of the pile. During the testing, data were recorded for all of the details of the pile driving process. According to the data analysis, it is clear that the compressive strain at the middle of the pile during driving is larger than that near the head and tip of the pile. Therefore, the middle of the prestressed concrete pile is the key location that should be preferentially monitored during pile driving. Meanwhile, when the hammer impacts the pile continuously, the obvious tension strain at the tip of the pile increases and the maximum dynamic tension strain reaches 56 με, which approaches the tension ultimate strain. This occurs because the frictional resistance of soil is small in the middle of the pile when the tip meets the significant supporting soil layer. This study can provide a reference for the mechanical performance monitoring deployment of precast prestressed concrete piles used in high-piled wharf structures in coastal ports. Full article

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18 pages, 992 KiB

Open AccessArticle

A Key Management Scheme for Mobile Wireless Sensor Networks

by Filippo Gandino^*

, Cesare Celozzi and Maurizio Rebaudengo

Dipartimento di Automatica e Informatica, Politecnico di Torino, 10129 Torino, Italy

Appl. Sci. 2017, 7(5), 490; https://doi.org/10.3390/app7050490 - 10 May 2017

Cited by 19 | Viewed by 4313

Abstract

Symmetric encryption is the most commonly employed security solution in wireless sensor networks (WSNs). In this paper, a new approach that employs public-key cryptography during key establishment is proposed. In a WSN, the main issue for public-key cryptography is represented by communication and [...] Read more.

Symmetric encryption is the most commonly employed security solution in wireless sensor networks (WSNs). In this paper, a new approach that employs public-key cryptography during key establishment is proposed. In a WSN, the main issue for public-key cryptography is represented by communication and computational overheads. In order to reduce these requirements, a new authentication system based on authentication tables is proposed. An analytical study shows that the proposed approach provided optimal protection against an adversary that compromised one or more nodes. A comparative analysis shows that, according to the dimension and the density of the network, the proposed approach can represent the best solution. Furthermore, an experimental analysis conducted on a real network shows that the proposed approach can be successfully applied to devices with limited computational power. Full article

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24 pages, 1195 KiB

Open AccessArticle

Joint Relay Selection and Resource Allocation for Energy-Efficient D2D Cooperative Communications Using Matching Theory

by Chen Xu¹, Junhao Feng¹, Biyao Huang², Zhenyu Zhou^1,*, Shahid Mumtaz³ and Jonathan Rodriguez^3,4

¹ School of Electrical and Electronic Engineering, North China Electric Power University, Beijing 102206, China

² State Grid Laboratory of Electric Power Communication Network Technology (Global Energy Interconnection Research Institute), Beijing 102209, China

³ Instituto de Telecomunicações, 1049-001 Aveiro, Portugal

⁴ University of South Wales, Pontypridd CF37 1DL, UK

Appl. Sci. 2017, 7(5), 491; https://doi.org/10.3390/app7050491 - 10 May 2017

Cited by 33 | Viewed by 7537

Abstract

Device-to-device (D2D) cooperative relay can improve network coverage and throughput by assisting users with inferior channel conditions to implement multi-hop transmissions. Due to the limited battery capacity of handheld equipment, energy efficiency is an important issue to be optimized. Considering the two-hop D2D [...] Read more.

Device-to-device (D2D) cooperative relay can improve network coverage and throughput by assisting users with inferior channel conditions to implement multi-hop transmissions. Due to the limited battery capacity of handheld equipment, energy efficiency is an important issue to be optimized. Considering the two-hop D2D relay communication scenario, this paper focuses on how to maximize the energy efficiency while guaranteeing the quality of service (QoS) requirements of both cellular and D2D links by jointly optimizing relay selection, spectrum allocation and power control. Since the four-dimensional matching involved in the joint optimization problem is NP-hard, a pricing-based two-stage matching algorithm is proposed to reduce dimensionality and provide a tractable solution. In the first stage, the spectrum resources reused by relay-to-receiver links are determined by a two-dimensional matching. Then, a three-dimensional matching is conducted to match users, relays and the spectrum resources reused by transmitter-to-relay links. In the process of preference establishment of the second stage, the optimal transmit power is solved to guarantee that the D2D link has the maximized energy efficiency. Simulation results show that the proposed algorithm not only has a good performance on energy efficiency, but also enhances the average number of served users compared to the case without any relay. Full article

(This article belongs to the Special Issue Green Wireless Networks)

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18 pages, 1239 KiB

Open AccessArticle

The Index System for the Development Level Evaluation of Regional Construction Industrialization: A Case Study in Jiangsu, China

by Ping Liu^1,2, Qiming Li^1,*, Liangliang Song¹ and Ruoyu Jia¹

¹ Department of Construction and Real Estate, School of Civil Engineering, Southeast University, Nanjing 210096, China

² School of Civil Engineering, Lanzhou University of Technology, Lanzhou 730050, China

Appl. Sci. 2017, 7(5), 492; https://doi.org/10.3390/app7050492 - 10 May 2017

Cited by 16 | Viewed by 6391

Abstract

In recent years, there have been concerns raised about construction industrialization in China, which have initiated a wave of policy change in both governmental and industrial organizations in order to change the mode of conventional construction. However, the current development level of regional [...] Read more.

In recent years, there have been concerns raised about construction industrialization in China, which have initiated a wave of policy change in both governmental and industrial organizations in order to change the mode of conventional construction. However, the current development level of regional construction industrialization (RCI) in China has not been well-characterized. This study screened preliminary index systems in five dimensions: technical, economic, sustainable, enterprise development and development environment. Based on the data gathered from the questionnaire surveys and subsequently analyzed, twenty-two critical evaluation indicators were identified. Analytic Hierarchy Process (AHP) was then employed to determine the weighting of each indicator. The evaluation method of the development level was formulated on the basis of the evaluation criteria. Jiangsu Province was used as an example in this study, with the development level of this province being comprehensively examined using a combination of the index system and evaluation method. The results show that Jiangsu has a relatively high RCI development level. The data from analysis scores of five dimensions and twenty-two indicators show that the index system is feasible, with evaluation results being consistent with actual practice. These findings provide a good practical reference for making decisions about how best to guide the development of RCI. Full article

(This article belongs to the Special Issue The Industrialization of the Building Construction Process)

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17 pages, 1422 KiB

Open AccessFeature PaperArticle

Conscious and Non-Conscious Measures of Emotion: Do They Vary with Frequency of Pornography Use?

by Sajeev Kunaharan¹, Sean Halpin¹

, Thiagarajan Sitharthan², Shannon Bosshard¹ and Peter Walla^1,3,4,*

¹ School of Psychology, Centre for Translational Neuroscience and Mental Health Research, University of Newcastle, Callaghan 2308, NSW, Australia

² Sydney Medical School, University of Sydney, Sydney 2006, NSW, Australia

³ Cognitive Neuroscience & Behaviour Lab (CanBeLab), Department of Psychology, Webster Vienna Private University, Palais Wenkheim, 1020 Vienna, Austria

⁴ Faculty of Psychology, Vienna University, 1010 Vienna, Austria

Appl. Sci. 2017, 7(5), 493; https://doi.org/10.3390/app7050493 - 11 May 2017

Cited by 15 | Viewed by 30752

Abstract

Increased pornography use has been a feature of contemporary human society, with technological advances allowing for high speed internet and relative ease of access via a multitude of wireless devices. Does increased pornography exposure alter general emotion processing? Research in the area of [...] Read more.

Increased pornography use has been a feature of contemporary human society, with technological advances allowing for high speed internet and relative ease of access via a multitude of wireless devices. Does increased pornography exposure alter general emotion processing? Research in the area of pornography use is heavily reliant on conscious self-report measures. However, increasing knowledge indicates that attitudes and emotions are extensively processed on a non-conscious level prior to conscious appraisal. Hence, this exploratory study aimed to investigate whether frequency of pornography use has an impact on non-conscious and/or conscious emotion processes. Participants (N = 52) who reported viewing various amounts of pornography were presented with emotion inducing images. Brain Event-Related Potentials (ERPs) were recorded and Startle Reflex Modulation (SRM) was applied to determine non-conscious emotion processes. Explicit valence and arousal ratings for each image presented were also taken to determine conscious emotion effects. Conscious explicit ratings revealed significant differences with respect to “Erotic” and “Pleasant” valence (pleasantness) ratings depending on pornography use. SRM showed effects approaching significance and ERPs showed changes in frontal and parietal regions of the brain in relation to “Unpleasant” and “Violent” emotion picture categories, which did not correlate with differences seen in the explicit ratings. Findings suggest that increased pornography use appears to have an influence on the brain’s non-conscious responses to emotion-inducing stimuli which was not shown by explicit self-report. Full article

(This article belongs to the Special Issue Sub- and Unconscious Information Processing in the Human Brain)

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31 pages, 4153 KiB

Open AccessReview

Shunt Damping Vibration Control Technology: A Review

by Bo Yan^1,2,3, Ke Wang², Zifan Hu³, Chuanyu Wu^1,* and Xinong Zhang³

¹ Faculty of Mechanical Engineering & Automation, Zhejiang Sci-Tech University, Hangzhou 310018, China

² Key Laboratory of Space Utilization, Technology and Engineering Center for Space Utilization, Chinese Academy of Sciences, Beijing 100094, China

³ State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University, Xi’an 710049, China

Appl. Sci. 2017, 7(5), 494; https://doi.org/10.3390/app7050494 - 11 May 2017

Cited by 97 | Viewed by 12171

Abstract

Smart materials and structures have attracted a significant amount of attention for their vibration control potential in engineering applications. Compared to the traditional active technique, shunt damping utilizes an external circuit across the terminals of smart structure based transducers to realize vibration control. [...] Read more.

Smart materials and structures have attracted a significant amount of attention for their vibration control potential in engineering applications. Compared to the traditional active technique, shunt damping utilizes an external circuit across the terminals of smart structure based transducers to realize vibration control. Transducers can simultaneously serve as an actuator and a sensor. Such unique advantage offers a great potential for designing sensorless devices to be used in structural vibration control and reduction engineering. The present literature combines piezoelectric shunt damping (PSD) and electromagnetic shunt damping (EMSD), establishes a unified governing equation of PSD and EMSD, and reports the unique vibration control performance of these shunts. The schematic of shunt circuits is given and demonstrated, and some common control principles and equations of these shunts are summarized. Finally, challenges and perspective of the shunt damping technology are discussed, and suggestions made based on the knowledge and experience of the authors. Full article

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28 pages, 10817 KiB

Open AccessArticle

Uniaxial Compressive Strength and Fracture Mode of Lake Ice at Moderate Strain Rates Based on a Digital Speckle Correlation Method for Deformation Measurement

by Jijian Lian, Qunan Ouyang, Xin Zhao^*, Fang Liu

and Chunfeng Qi

State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300072, China

Appl. Sci. 2017, 7(5), 495; https://doi.org/10.3390/app7050495 - 11 May 2017

Cited by 20 | Viewed by 7317

Abstract

Better understanding of the complex mechanical properties of ice is the foundation to predict the ice fail process and avoid potential ice threats. In the present study, uniaxial compressive strength and fracture mode of natural lake ice are investigated over moderate strain-rate range [...] Read more.

Better understanding of the complex mechanical properties of ice is the foundation to predict the ice fail process and avoid potential ice threats. In the present study, uniaxial compressive strength and fracture mode of natural lake ice are investigated over moderate strain-rate range of 0.4–10 s⁻¹ at −5 °C and −10 °C. The digital speckle correlation method (DSCM) is used for deformation measurement through constructing artificial speckle on ice sample surface in advance, and two dynamic load cells are employed to measure the dynamic load for monitoring the equilibrium of two ends’ forces under high-speed loading. The relationships between uniaxial compressive strength and strain-rate, temperature, loading direction, and air porosity are investigated, and the fracture mode of ice at moderate rates is also discussed. The experimental results show that there exists a significant difference between true strain-rate and nominal strain-rate derived from actuator displacement under dynamic loading conditions. Over the employed strain-rate range, the dynamic uniaxial compressive strength of lake ice shows positive strain-rate sensitivity and decreases with increasing temperature. Ice obtains greater strength values when it is with lower air porosity and loaded vertically. The fracture mode of ice seems to be a combination of splitting failure and crushing failure. Full article

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13 pages, 3243 KiB

Open AccessArticle

Random Vibration Suppression of a Truss Core Sandwich Panel Using Independent Modal Resonant Shunt and Modal Criterion

by Kongming Guo^* and Yalan Xu

Research Center of Applied Mechanics, School of Mechano-Electronic Engineering, Xidian University, P.O. Box 187, Xi’an 710071, China

Appl. Sci. 2017, 7(5), 496; https://doi.org/10.3390/app7050496 - 11 May 2017

Cited by 8 | Viewed by 4541

Abstract

The aim of this paper is to suppress the random spatial vibration of the face sheet of a lightly damped truss core sandwich panel structure. Because broad-bandwidth vibration energy is concentrated in resonance peaks for lightly damped structures, an independent modal resonant shunt [...] Read more.

The aim of this paper is to suppress the random spatial vibration of the face sheet of a lightly damped truss core sandwich panel structure. Because broad-bandwidth vibration energy is concentrated in resonance peaks for lightly damped structures, an independent modal resonant shunt control method is utilized to add damping ratios to the chosen modes. In this method, each piezoelectric transducer is connected to a single resonant shunt which is tuned to control the vibration of a single mode. An H₂ norm sensitivity-based modal criterion is proposed in order to determine which modes to control under a given bandwidth of excitation and input-output condition. Numerical simulation is implemented while control strategies with different controlled modes are compared. The result shows that the independent modal resonant shunt control method can suppress random vibration response of the face sheet by using only a few piezoelectric transducers, and the proposed modal criterion can be used to determine which modes to control. Full article

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31 pages, 525 KiB

Open AccessFeature PaperReview

The State-of-the-Art on Framework of Vibration-Based Structural Damage Identification for Decision Making

by Xuan Kong, Chun-Sheng Cai^* and Jiexuan Hu

Department of Civil and Environmental Engineering, Louisiana State University, Baton Rouge, LA 70803, USA

Appl. Sci. 2017, 7(5), 497; https://doi.org/10.3390/app7050497 - 11 May 2017

Cited by 161 | Viewed by 12151

Abstract

Research on detecting structural damage at the earliest possible stage has been an interesting topic for decades. Among them, the vibration-based damage detection method as a global technique is especially pervasive. The present study reviewed the state-of-the-art on the framework of vibration-based damage [...] Read more.

Research on detecting structural damage at the earliest possible stage has been an interesting topic for decades. Among them, the vibration-based damage detection method as a global technique is especially pervasive. The present study reviewed the state-of-the-art on the framework of vibration-based damage identification in different levels including the prediction of the remaining useful life of structures and the decision making for proper actions. This framework consists of several major parts including the detection of damage occurrence using response-based methods, building reasonable structural models, selecting damage parameters and constructing objective functions with sensitivity analysis, adopting optimization techniques to solve the problem, predicting the remaining useful life of structures, and making decisions for the next actions. For each part, the commonly used methods were reviewed and the merits and drawbacks were summarized to give recommendations. This framework is aimed to guide the researchers and engineers to implement step by step the structure damage identification using vibration measurements. Finally, the future research work in this field is recommended. Full article

(This article belongs to the Special Issue Structural Health Monitoring (SHM) of Civil Structures)

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16 pages, 7771 KiB

Open AccessArticle

Design of a Binocular Pupil and Gaze Point Detection System Utilizing High Definition Images

by Yilmaz Durna^*

and Fikret Ari

Department of Electrical and Electronics Engineering, Ankara University, Ankara 06830, Turkey

Appl. Sci. 2017, 7(5), 498; https://doi.org/10.3390/app7050498 - 11 May 2017

Cited by 9 | Viewed by 8665

Abstract

This study proposes a novel binocular pupil and gaze detection system utilizing a remote full high definition (full HD) camera and employing LabVIEW. LabVIEW is inherently parallel and has fewer time-consuming algorithms. Many eye tracker applications are monocular and use low resolution cameras [...] Read more.

This study proposes a novel binocular pupil and gaze detection system utilizing a remote full high definition (full HD) camera and employing LabVIEW. LabVIEW is inherently parallel and has fewer time-consuming algorithms. Many eye tracker applications are monocular and use low resolution cameras due to real-time image processing difficulties. We utilized the computer’s direct access memory channel for rapid data transmission and processed full HD images with LabVIEW. Full HD images make easier determinations of center coordinates/sizes of pupil and corneal reflection. We modified the camera so that the camera sensor passed only infrared (IR) images. Glints were taken as reference points for region of interest (ROI) area selection of the eye region in the face image. A morphologic filter was applied for erosion of noise, and a weighted average technique was used for center detection. To test system accuracy with 11 participants, we produced a visual stimulus set up to analyze each eye’s movement. Nonlinear mapping function was utilized for gaze estimation. Pupil size, pupil position, glint position and gaze point coordinates were obtained with free natural head movements in our system. This system also works at 2046 × 1086 resolution at 40 frames per second. It is assumed that 280 frames per second for 640 × 480 pixel images is the case. Experimental results show that the average gaze detection error for 11 participants was 0.76° for the left eye, 0.89° for right eye and 0.83° for the mean of two eyes. Full article

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11 pages, 4247 KiB

Open AccessArticle

Human-Like Walking with Heel Off and Toe Support for Biped Robot

by Yixiang Liu^1,2,3

, Xizhe Zang^1,*, Shuai Heng¹, Zhenkun Lin¹ and Jie Zhao¹

¹ State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150080, China

² Legs + Walking Lab, Shirley Ryan AbilityLab (Formerly the Rehabilitation Institute of Chicago), Chicago, IL 60611, USA

³ Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL 60611, USA

Appl. Sci. 2017, 7(5), 499; https://doi.org/10.3390/app7050499 - 18 May 2017

Cited by 8 | Viewed by 9868

Abstract

The under-actuated foot rotation that the heel of the stance leg lifts off the ground and the body rotates around the stance toe is an important feature in human walking. However, it is absent in the realized walking gait for the majority of [...] Read more.

The under-actuated foot rotation that the heel of the stance leg lifts off the ground and the body rotates around the stance toe is an important feature in human walking. However, it is absent in the realized walking gait for the majority of biped robots because of the difficulty and complexity in the control it brings about. In this paper, a hybrid control approach aiming to integrate the main characteristics of human walking into a simulated seven-link biped robot is presented and then verified with simulations. The bipedal robotic gait includes a fully actuated single support phase with the stance heel supporting the body, an under-actuated single support phase, with the stance toe supporting the body, and an instantaneous double support phase when the two legs exchange their roles. The walking controller combines virtual force control and foot placement control, which are applied to the stance leg and the swing leg, respectively. The virtual force control assumes that there is a virtual force which can generate the desired torso motion on the center of mass of the torso link, and then the virtual force is applied through the real torques on each actuated joint of the stance leg to create the same effect that the virtual force would have created. The foot placement control uses a path tracking controller to follow the predefined trajectory of the swing foot when walking forward. The trajectories of the torso and the swing foot are generated based on the cart-cable model. Co-simulations in Adams and MATLAB show that the desired gait is achieved with a biped robot under the action of the proposed method. Full article

(This article belongs to the Special Issue Bio-Inspired Robotics)

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19 pages, 922 KiB

Open AccessArticle

A Fast Motion Parameters Estimation Method Based on Cross-Correlation of Adjacent Echoes for Wideband LFM Radars

by Yi-Xiong Zhang^1,*

, Ru-Jia Hong^1,†, Cheng-Fu Yang^2,*, Yun-Jian Zhang^1,†, Zhen-Miao Deng^1,† and Sheng Jin^3,†

¹ School of Information Science and Engineering, Xiamen University, Xiamen 361005, China

² Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan

³ Beijing Institute of Tracking and Telecommunications Technology, Beijing 100094, China

^† These authors contributed equally to this work.

Appl. Sci. 2017, 7(5), 500; https://doi.org/10.3390/app7050500 - 15 May 2017

Cited by 6 | Viewed by 5766

Abstract

In wideband radar systems, the performance of motion parameters estimation can significantly affect the performance of object detection and the quality of inverse synthetic aperture radar (ISAR) imaging. Although the traditional motion parameters estimation methods can reduce the range migration (RM) and Doppler [...] Read more.

In wideband radar systems, the performance of motion parameters estimation can significantly affect the performance of object detection and the quality of inverse synthetic aperture radar (ISAR) imaging. Although the traditional motion parameters estimation methods can reduce the range migration (RM) and Doppler frequency migration (DFM) effects in ISAR imaging, the computational complexity is high. In this paper, we propose a new fast non-parameter-searching method for motion parameters estimation based on the cross-correlation of adjacent echoes (CCAE) for wideband LFM signals. A cross-correlation operation is carried out for two adjacent echo signals, then the motion parameters can be calculated by estimating the frequency of the correlation result. The proposed CCAE method can be applied directly to the stretching system, which is commonly adopted in wideband radar systems. Simulation results demonstrate that the new method can achieve better estimation performances, with much lower computational cost, compared with existing methods. The experimental results on real radar datasets are also evaluated to verify the effectiveness and superiority of the proposed method compared to the state-of-the-art existing methods. Full article

(This article belongs to the Special Issue Selected Papers from IEEE ICASI 2017)

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12 pages, 8954 KiB

Open AccessArticle

Swirling Gas Jet-Assisted Laser Trepanning for a Galvanometer-Scanned CO₂ Laser

by Chao-Ching Ho^1,*

, Ke-Ying Shen², Chang-Sheng Chen¹, Yuan-Jen Chang², Jin-Chen Hsu² and Chia-Lung Kuo²

¹ Graduate Institute of Manufacturing Technology and Department of Mechanical Engineering, National Taipei University of Technology, Taipei 10608, Taiwan

² Department of Mechanical Engineering, National Yunlin University of Science and Technology, Douliou, Yunlin 64002, Taiwan

Appl. Sci. 2017, 7(5), 502; https://doi.org/10.3390/app7050502 - 17 May 2017

Cited by 1 | Viewed by 6049

Abstract

Laser-drilled hole arrays are part of an important field that aim to improve efficiency without affecting the quality of laser-drilled holes. In this paper, a swirling gas jet was implemented to assist with laser trepanning for a galvanometer scanned CO₂ laser. The [...] Read more.

Laser-drilled hole arrays are part of an important field that aim to improve efficiency without affecting the quality of laser-drilled holes. In this paper, a swirling gas jet was implemented to assist with laser trepanning for a galvanometer scanned CO₂ laser. The proposed swirling gas jet is based on laser trepanning. This swirling gas jet nozzle was composed of four inlet tubes to produce the flow of the vortex. Then, the plume particles were excluded, and spatter on the surface of the workpiece decreased. Thus, this approach can mitigate the problem of overcooling. This study manipulated the appropriate parameter settings, which were simulated by computational fluid dynamics software ANSYS CFX. The proposed swirling gas jet can be used with galvanometer-based scanner systems to keep the laser beam from interference by spatter. In addition, a hollow position of the vortex was achieved by using the four inlet tubes, which resulted in pressure asymmetry in the nozzle and velocity distribution on the surface of the workpiece. The experiment verified that the depth of processing could be enhanced by 110% when trepanning at a scanning speed of 30 mm/s, and that the removal of volume could be enhanced by 71% in trepanning at a diameter of 1 mm by using a swirl assistant compared with a non-assisted condition. Furthermore, the material removal rate of the swirling jet increases when the machining area of the galvanometer-based scanner is larger. Full article

(This article belongs to the Special Issue Selected Papers from the 2016 International Conference on Inventions)

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11 pages, 2696 KiB

Open AccessFeature PaperArticle

On the Visualization of Gas Metal Arc Welding Plasma and the Relationship Between Arc Length and Voltage

by Emanuel B. F. Dos Santos^1,*

, Letícia H. Kuroiwa^1,†, A. Felipe C. Ferreira^1,‡, Rob Pistor² and Adrian P. Gerlich¹

¹ Centre for Advanced Materials Joining (CAMJ), Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada

² Liburdi Engineering Limited, 400 Highway 6 North, Dundas, ON L9H 7K4, Canada

^† Current address: Department of Materials Engineering, Federal University of Sao Carlos (UFSCar), Rodovia Washington Luís /km 235, São Carlos, CEP 13565-905, São Paulo, Brazil.

^‡ Current address: Department of Mechanical Engineering, Polytechnic Institute, Pontifical Catholic University of Minas Gerais (PUC Minas), Avenida Dom José Gaspar 500 , Belo Horizonte, CEP 30535-901, Minas Gerais, Brazil.

Appl. Sci. 2017, 7(5), 503; https://doi.org/10.3390/app7050503 - 15 May 2017

Cited by 19 | Viewed by 7773

Abstract

In this article, the camera settings for high-speed imaging of the arc, metal transfer, and weld pool in gas metal arc welding (GMAW) are investigated. The results show that by only changing camera exposure times and the selection of narrow bandpass filters, images [...] Read more.

In this article, the camera settings for high-speed imaging of the arc, metal transfer, and weld pool in gas metal arc welding (GMAW) are investigated. The results show that by only changing camera exposure times and the selection of narrow bandpass filters, images that reveal features of the arc such as the iron vapor-dominated region, metal transfer and weld pool behavior can be produced without the need for external light sources. Using the images acquired, the arc length was measured and the relationship between arc length and arc voltage is discussed. The results show that for low values of current, the measured welding voltage increases with increasing arc length; however, for high current values, the arc voltage increases even though the measured arc length becomes shorter. It is suggested that the increase in arc voltage for high values of welding current is due to the increased evaporation of the wire electrode which decreases the plasma temperature and consequently the arc plasma electrical conductivity. Full article

(This article belongs to the Special Issue Gas Metal Arc Welding)

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19 pages, 15530 KiB

Open AccessArticle

Advanced Emergency Braking Control Based on a Nonlinear Model Predictive Algorithm for Intelligent Vehicles

by Ronghui Zhang^1,2, Kening Li^3,4,*, Zhaocheng He^1,2,†, Haiwei Wang^5,† and Feng You^5,†

¹ Research Center of Intelligent Transportation System, School of Engineering, Sun Yat-sen University, Guangzhou 510275, China

² Guangdong Key Laboratory of Intelligent Transportation System, School of Engineering, Sun Yat-sen University, Guangzhou 510275, China

³ School of Traffic and Environment, Shenzhen Institute of Information Technology, Shenzhen 518172, China

⁴ State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiaotong University, Shanghai 200240, China

⁵ School of Civil Engineering and Transportation, South China University of Technology, Guangzhou 510640, China

^† These authors contributed equally to this work.

Appl. Sci. 2017, 7(5), 504; https://doi.org/10.3390/app7050504 - 16 May 2017

Cited by 45 | Viewed by 10256

Abstract

Focusing on safety, comfort and with an overall aim of the comprehensive improvement of a vision-based intelligent vehicle, a novel Advanced Emergency Braking System (AEBS) is proposed based on Nonlinear Model Predictive Algorithm. Considering the nonlinearities of vehicle dynamics, a vision-based longitudinal vehicle [...] Read more.

Focusing on safety, comfort and with an overall aim of the comprehensive improvement of a vision-based intelligent vehicle, a novel Advanced Emergency Braking System (AEBS) is proposed based on Nonlinear Model Predictive Algorithm. Considering the nonlinearities of vehicle dynamics, a vision-based longitudinal vehicle dynamics model is established. On account of the nonlinear coupling characteristics of the driver, surroundings, and vehicle itself, a hierarchical control structure is proposed to decouple and coordinate the system. To avoid or reduce the collision risk between the intelligent vehicle and collision objects, a coordinated cost function of tracking safety, comfort, and fuel economy is formulated. Based on the terminal constraints of stable tracking, a multi-objective optimization controller is proposed using the theory of non-linear model predictive control. To quickly and precisely track control target in a finite time, an electronic brake controller for AEBS is designed based on the Nonsingular Fast Terminal Sliding Mode (NFTSM) control theory. To validate the performance and advantages of the proposed algorithm, simulations are implemented. According to the simulation results, the proposed algorithm has better integrated performance in reducing the collision risk and improving the driving comfort and fuel economy of the smart car compared with the existing single AEBS. Full article

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21 pages, 13544 KiB

Open AccessArticle

An Efficient Compensation Method for Limited-View Photoacoustic Imaging Reconstruction Based on Gerchberg–Papoulis Extrapolation

by Jin Wang¹ and Yuanyuan Wang^1,2,*

¹ Department of Electronic Engineering, Fudan University, No. 220 Handan Road, Shanghai 200433, China

² Key Laboratory of Medical Imaging Computing and Computer Assisted Intervention (MICCAI) of Shanghai, Fudan University, Shanghai 200433, China

Appl. Sci. 2017, 7(5), 505; https://doi.org/10.3390/app7050505 - 17 May 2017

Cited by 8 | Viewed by 6108

Abstract

The reconstruction for limited-view scanning, though often the case in practice, has remained a difficult issue for photoacoustic imaging (PAI). The incompleteness of sampling data will cause serious artifacts and fuzziness in those missing views and it will heavily affect the quality of [...] Read more.

The reconstruction for limited-view scanning, though often the case in practice, has remained a difficult issue for photoacoustic imaging (PAI). The incompleteness of sampling data will cause serious artifacts and fuzziness in those missing views and it will heavily affect the quality of the image. To solve the problem of limited-view PAI, a compensation method based on the Gerchberg–Papoulis (GP) extrapolation is applied into PAI. Based on the known data, missing detectors elements are estimated and the image in the missing views is then compensated using the Fast Fourier Transform (FFT). To accelerate the convergence speed of the algorithm, the total variation (TV)-based iterative algorithm is incorporated into the GP extrapolation-based FFT-utilized compensation method (TV-GPEF). The effective variable splitting and Barzilai–Borwein based method is adopted to solve the optimization problem. Simulations and in vitro experiments for both limited-angle circular scanning and straight-line scanning are conducted to validate the proposed algorithm. Results show that the proposed algorithm can greatly suppress the artifacts caused by the missing views and enhance the edges and the details of the image. It can be indicated that the proposed TV-GPEF algorithm is efficient for limited-view PAI. Full article

(This article belongs to the Special Issue Biomedical Photoacoustic and Thermoacoustic Imaging)

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12 pages, 4623 KiB

Open AccessArticle

A New Health Assessment Index of Tunnel Lining Based on the Digital Inspection of Surface Cracks

by Xuezhen Wu¹, Yujing Jiang^1,4,*

, Jianhua Wang¹, Kusaba Masaya¹, Tetsuya Taniguchi² and Takahide Yamato³

¹ Graduate School of Engineering, Nagasaki University, Nagasaki 852-8521, Japan

² West Nippon Expressway Engineering Kyushu Co., Ltd., Fukuoka 810-0073, Japan

³ West Nippon Expressway Co., Ltd., Nagasaki 854-0063, Japan

⁴ State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao 266590, China

Appl. Sci. 2017, 7(5), 507; https://doi.org/10.3390/app7050507 - 12 May 2017

Cited by 21 | Viewed by 7623

Abstract

The stability assessment of aged tunnel linings are mainly evaluated based on the visual inspection, and the Tunnel-lining Crack Index (TCI) is one of the most widely used tunnel lining health assessment indexes in Japan. However, the intersection and distribution of cracks, which [...] Read more.

The stability assessment of aged tunnel linings are mainly evaluated based on the visual inspection, and the Tunnel-lining Crack Index (TCI) is one of the most widely used tunnel lining health assessment indexes in Japan. However, the intersection and distribution of cracks, which could influence the stability of tunnel lining greatly, were not considered in TCI. A new method was proposed for the health assessment of tunnel lining, which evaluated the lining states according to the fractal dimension of cracks. Based on the machine vision-based method, the crack image could be extracted efficiently. The fractal dimension of lining cracks in one span could be obtained in a few minutes. A series of comparative tests and field tests were conducted to evaluate the validity of this new method. The comparative tests confirmed that fractal dimension was able to characterize the density, width, and distribution of cracks. The intersection of cracks, which would increase the risk of lining collapse, could also increase the fractal dimension. The fractal dimensions of tunnel lining cracks were obtained according to the digital inspection test of Hidake Tunnel in Japan for all the 65 spans. Moreover, the TCI was obtained through statistical methods. The correlation between fractal dimension and TCI of tunnel lining was studied. The significance of the new evaluation index is that it can identify the unusual spans of tunnel lining and provide a basis for further internal testing. As a complement to the conventional visual inspection method, the fractal dimension of the cracks is a promising health assessment index. Full article

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10 pages, 1133 KiB

Open AccessArticle

Immobilized TiO₂-Polyethylene Glycol: Effects of Aeration and pH of Methylene Blue Dye

by Wan Izhan Nawawi^1,*, Raihan Zaharudin^1,2, Ahmad Zuliahani¹, Dyia Syaleyana Shukri¹, Tun Firdaus Azis¹ and Zainab Razali¹

¹ Faculty of Applied Sciences, Universiti Teknologi MARA, Perlis, Arau 02600, Malaysia

² Faculty of Applied Sciences, Universiti Teknologi MARA, Selangor, Shah Alam 40450, Malaysia

Appl. Sci. 2017, 7(5), 508; https://doi.org/10.3390/app7050508 - 12 May 2017

Cited by 28 | Viewed by 5467

Abstract

Immobilized TiO₂ and immobilized TiO₂-polyethylene glycol (TiO₂/PEG) films have been prepared via brush coating method. The formulation of immobilized TiO₂ film was prepared by mixing distilled water with P25, while the formulation containing P25 combined with 8% [...] Read more.

Immobilized TiO₂ and immobilized TiO₂-polyethylene glycol (TiO₂/PEG) films have been prepared via brush coating method. The formulation of immobilized TiO₂ film was prepared by mixing distilled water with P25, while the formulation containing P25 combined with 8% PEG in distilled water was used in preparing immobilized TiO₂/PEG. A double sided adhesive tape (DSAT) was stacked onto a glass surface prior to coating with the formulations and annealing by a thermal treatment at 100 °C for 15 min. The photocatalytic activity of immobilized photocatalysts was evaluated under photodegradation of methylene blue (MB). It was observed that immobilized TiO₂/PEG has showed a higher rate of photocatalytic activity compared to immobilize TiO₂. The X-ray photoelectron spectroscopy and Fourier transform infrared (FT-IR) spectra of immobilized TiO₂/PEG sample proved that the existence of C=O led to enhanced photoactivity efficiency under normal light and visible light irradiations. The photocatalytic activity performance of immobilized TiO₂/PEG was the highest at 75 mL·min⁻¹ aeration rate and pH 11 of MB dye. The correlation between of all these parameters was investigated in this study. Full article

(This article belongs to the Section Chemical and Molecular Sciences)

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24 pages, 316 KiB

Open AccessReview

A State of the Art Review of Modal-Based Damage Detection in Bridges: Development, Challenges, and Solutions

by John J. Moughty^* and Joan R. Casas^*

Department of Civil and Environmental Engineering, Technical University of Catalonia-BarcelonaTech, 08034 Barcelona, Spain

Appl. Sci. 2017, 7(5), 510; https://doi.org/10.3390/app7050510 - 13 May 2017

Cited by 197 | Viewed by 11814

Abstract

Traditionally, damage identification techniques in bridges have focused on monitoring changes to modal-based Damage Sensitive Features (DSFs) due to their direct relationship with structural stiffness and their spatial information content. However, their progression to real-world applications has not been without its challenges and [...] Read more.

Traditionally, damage identification techniques in bridges have focused on monitoring changes to modal-based Damage Sensitive Features (DSFs) due to their direct relationship with structural stiffness and their spatial information content. However, their progression to real-world applications has not been without its challenges and shortcomings, mainly stemming from: (1) environmental and operational variations; (2) inefficient utilization of machine learning algorithms for damage detection; and (3) a general over-reliance on modal-based DSFs alone. The present paper provides an in-depth review of the development of modal-based DSFs and a synopsis of the challenges they face. The paper then sets out to addresses the highlighted challenges in terms of published advancements and alternatives from recent literature. Full article

(This article belongs to the Special Issue Structural Health Monitoring (SHM) of Civil Structures)

10 pages, 3513 KiB

Open AccessArticle

Facile Synthesis of α-MnO₂ with a 3D Staghorn Coral-like Micro-Structure Assembled by Nano-Rods and Its Application in Electrochemical Supercapacitors

by Yonghong Bing¹, Lei Zhang^1,2, Shichun Mu³

and Jiujun Zhang^2,*

¹ National Research Council Canada, 4250 Wesbrook Mall, Vancouver, BC V6T 1W5, Canada

² College of Science, Shanghai University, 99 Shangda Road, Shanghai 200444, China

³ State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China

Appl. Sci. 2017, 7(5), 511; https://doi.org/10.3390/app7050511 - 13 May 2017

Cited by 8 | Viewed by 5693

Abstract

Abstract: Manganese oxides with an alpha crystal structure are synthesized via combined solid-state reaction and wet chemical processing, which is a simple and inexpensive synthetic route easy for mass production. The effects of the synthetic reaction duration and the temperature of acid [...] Read more.

Abstract: Manganese oxides with an alpha crystal structure are synthesized via combined solid-state reaction and wet chemical processing, which is a simple and inexpensive synthetic route easy for mass production. The effects of the synthetic reaction duration and the temperature of acid treatments on crystal structure, morphology, and electrochemical capacitive properties of α-MnO₂ are discussed. It is evidenced that the samples treated in acid for a longer time at 25 °C display the uniform nanorods that are aggregated to form micro-buildings with fine features on the surface of rods. This microstructure possesses large surface areas and more active sites that are easy to access electrochemically, leading to a better electrochemical capacitive performance. We expected that these results would provide the practical information for shape- and morphology-controlled synthesis for nanostructured functional materials in supercapacitor applications. Full article

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15 pages, 2598 KiB

Open AccessArticle

Development of Green Geopolymer Using Agricultural and Industrial Waste Materials with High Water Absorbency

by Zeynab Emdadi^1,4,*, Nilofar Asim^1,*, Mohamad Hassan Amin², Mohd Ambar Yarmo³, Ali Maleki⁴

, Mojtaba Azizi^4,5 and Kamaruzzaman Sopian¹

¹ Solar Energy Research Institute, Universiti Kebangsaan Malaysia, Bangi 43600, Selangor, Malaysia

² Centre for Advanced Materials & Industrial Chemistry, School of Applied Science RMIT University, Melbourne, VIC 3001, Australia

³ Department of Chemistry, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi 43600, Selangor, Malaysia

⁴ Catalysts and Organic Synthesis Research Laboratory, Department of Chemistry, Iran University of Science and Technology, P.O. Box 1684613114, Tehran, Iran

⁵ Department of Chemistry, K.N. Toosi University of Technology, P.O. Box 15875-4416, Tehran, Iran

Appl. Sci. 2017, 7(5), 514; https://doi.org/10.3390/app7050514 - 16 May 2017

Cited by 64 | Viewed by 8012

Abstract

Geopolymer is a promising porous material that can be used for evaporative cooling applications. Developing a greener geopolymer using agricultural and industrial wastes is a promising research area. In this study, we utilize rice husk (RH), rice husk ash (RHA), metakaolin (MK), ground [...] Read more.

Geopolymer is a promising porous material that can be used for evaporative cooling applications. Developing a greener geopolymer using agricultural and industrial wastes is a promising research area. In this study, we utilize rice husk (RH), rice husk ash (RHA), metakaolin (MK), ground granulated blast furnace slag (GGBS), and palm oil fuel ash (POFA) to prepare geopolymer pastes, with alkali liquid as an activator. Many geopolymer samples have been prepared as per the Design of Experimental software (DOE), and its corresponding response surface mode and central composite design and later they were characterized. The samples were cured in an oven for 2 h at 80 °C, and thereafter stored at room temperature (~25–30 °C) prior to being tested for its water absorption and compressive strength. The effect of the different composition of precursors on water absorption, density, porosity, and the compressive strength of the prepared geopolymers have been investigated. The results showed that the compressive strength of geopolymers is directly proportional to the ratio of the alkali liquid. Post-optimization, the best geopolymer paste mixture was confirmed to contain 10% of RH, 15% RHA, 35% MK, 10% POFA and 30% of GGBS, with 72% desirability for maximum water absorption (~38%) and compressive strength (4.9 MPa). The results confirmed its applicability for evaporative cooling. Full article

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15 pages, 4238 KiB

Open AccessFeature PaperArticle

Detection of Pitting in Gears Using a Deep Sparse Autoencoder

by Yongzhi Qu¹

, Miao He²

, Jason Deutsch² and David He^2,3,*

¹ School of Mechanical and Electronic Engineering, Wuhan University of Technology, Wuhan 430070, China

² Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, IL 60607, USA

³ College of Mechanical Engineering and Automation, Northeastern University, Shenyang 110819, China

Appl. Sci. 2017, 7(5), 515; https://doi.org/10.3390/app7050515 - 16 May 2017

Cited by 55 | Viewed by 8776

Abstract

In this paper; a new method for gear pitting fault detection is presented. The presented method is developed based on a deep sparse autoencoder. The method integrates dictionary learning in sparse coding into a stacked autoencoder network. Sparse coding with dictionary learning is [...] Read more.

In this paper; a new method for gear pitting fault detection is presented. The presented method is developed based on a deep sparse autoencoder. The method integrates dictionary learning in sparse coding into a stacked autoencoder network. Sparse coding with dictionary learning is viewed as an adaptive feature extraction method for machinery fault diagnosis. An autoencoder is an unsupervised machine learning technique. A stacked autoencoder network with multiple hidden layers is considered to be a deep learning network. The presented method uses a stacked autoencoder network to perform the dictionary learning in sparse coding and extract features from raw vibration data automatically. These features are then used to perform gear pitting fault detection. The presented method is validated with vibration data collected from gear tests with pitting faults in a gearbox test rig and compared with an existing deep learning-based approach. Full article

(This article belongs to the Special Issue Deep Learning Based Machine Fault Diagnosis and Prognosis)

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20 pages, 2901 KiB

Open AccessFeature PaperConcept Paper

Sintering of Two Viscoelastic Particles: A Computational Approach

by Caroline Balemans^1,2, Martien A. Hulsen¹ and Patrick D. Anderson^1,*

¹ Polymer Technology, Department of Mechanical Engineering, Eindhoven University of Technology, Eindhoven, 5600 MB, The Netherlands

² Brightlands Materials Center, Geleen, 6167 RD, The Netherlands

Appl. Sci. 2017, 7(5), 516; https://doi.org/10.3390/app7050516 - 16 May 2017

Cited by 22 | Viewed by 5872

Abstract

Selective laser sintering (SLS) is a high-resolution additive manufacturing fabrication technique. To fully understand the process, we developed a computational model, using the finite element method, to solve the flow problem of sintering two viscoelastic particles. The flow is assumed to be isothermal [...] Read more.

Selective laser sintering (SLS) is a high-resolution additive manufacturing fabrication technique. To fully understand the process, we developed a computational model, using the finite element method, to solve the flow problem of sintering two viscoelastic particles. The flow is assumed to be isothermal and the particles to be in a liquid state, where their rheology is described using the Giesekus and XPP constitutive models. In this work, we assess the parameters that define this problem, such as the initial geometry, the Deborah number and other dimensionless parameters present in the rheological models. In particular, the conformation tensor is considered, which is a measure for the polymeric strain and plays an important role in the crystallization kinetics of semicrystalline polymers like polyamide 12, usually used in SLS. Full article

(This article belongs to the Special Issue Materials for 3D Printing)

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16 pages, 5271 KiB

Open AccessArticle

Fire Damage Assessment of Reinforced Concrete Structures Using Fuzzy Theory

by Hae-Chang Cho¹

, Deuck Hang Lee¹

, Hyunjin Ju¹, Hyun-Cheol Park², Heung-Youl Kim³ and Kang Su Kim^1,*

¹ Department of Architectural Engineering, University of Seoul, Seoul 02504, Korea

² SAMPYO P&C, Seoul 03152, Korea

³ Fire Safety Research Division, Korea Institute of Construction Technology, Hwaseong-si 18544, Gyeonggi-do, Korea

Appl. Sci. 2017, 7(5), 518; https://doi.org/10.3390/app7050518 - 16 May 2017

Cited by 29 | Viewed by 7386

Abstract

Once a reinforced concrete (RC) structure is damaged by fire, the fire damage assessment should proceed to take appropriate post-fire actions, including the decision-making of whether it can be repaired for reuse or not. Since the assessment results of current fire damage diagnosis [...] Read more.

Once a reinforced concrete (RC) structure is damaged by fire, the fire damage assessment should proceed to take appropriate post-fire actions, including the decision-making of whether it can be repaired for reuse or not. Since the assessment results of current fire damage diagnosis methods, however, highly depend on the subjective judgment of inspectors, it is hard to ensure their objectiveness and reliability. This study, therefore, aims to develop a new fire damage diagnosis system (FDDS) based on fuzzy theory that can provide objective and comprehensive evaluation results by considering all of the damage conditions observed from the inspection on RC structural members exposed to fire. In addition, the FDDS was applied to an actual fire-damaged case reported by the Architectural Institute of Japan (AIJ, 2009), and it appears that the proposed method provides a reasonable estimation on the fire damage grade of the fire-damaged RC members. Full article

(This article belongs to the Special Issue Structural Health Monitoring (SHM) of Civil Structures)

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13 pages, 5352 KiB

Open AccessArticle

Probing Dynamics in Colloidal Crystals with Pump-Probe Experiments at LCLS: Methodology and Analysis

by Nastasia Mukharamova¹, Sergey Lazarev^1,2

, Janne-Mieke Meijer^3,9

, Matthieu Chollet⁴, Andrej Singer⁵, Ruslan P. Kurta^1,10

, Dmitry Dzhigaev¹, Oleg Yu. Gorobtsov¹, Garth Williams^4,11, Diling Zhu⁴, Yiping Feng⁴, Marcin Sikorski^4,10, Sanghoon Song⁴, Anatoly G. Shabalin^1,12, Tatiana Gurieva¹, Elena A. Sulyanova⁶

, Oleksandr M. Yefanov⁷ and Ivan A. Vartanyants^1,8,*

¹ Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22607 Hamburg, Germany

² National Research Tomsk Polytechnic University (TPU), Pr. Lenina 30, 634050 Tomsk, Russia

³ Van ’t Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science, Utrecht University, Padualaan 8, 3508 TB Utrecht, The Netherlands

⁴ SLAC National Accelerator Laboratory, 2575 Sand Hill Rd, Menlo Park, CA 94025, USA

⁵ UC San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA

⁶ Shubnikov Institute of Crystallography RAS, Leninskii Pr. 59, 119333 Moscow, Russia

⁷ Center for Free-Electron Laser Science, DESY, Notkestraße 85, D-22607 Hamburg, Germany

⁸ National Research Nuclear University MEPhI, Kashirskoye Ch. 31, 115409 Moscow, Russia

⁹ Present address: Department of Physics, University of Konstanz, D-78457 Konstanz, Germany

¹⁰ Present address: European XFEL GmbH, Holzkoppel 4, D-22869 Schenefeld, Germany

¹¹ Present address: NSLS-II, Brookhaven National Laboratory, Upton, NY 11973-5000, USA

¹² Present address: UC San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA

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Appl. Sci. 2017, 7(5), 519; https://doi.org/10.3390/app7050519 - 19 May 2017

Cited by 4 | Viewed by 6780

Abstract

We present results of the studies of dynamics in colloidal crystals performed by pump-probe experiments using an X-ray free-electron laser (XFEL). Colloidal crystals were pumped with an infrared laser at a wavelength of 800 nm with varying power and probed by XFEL pulses [...] Read more.

We present results of the studies of dynamics in colloidal crystals performed by pump-probe experiments using an X-ray free-electron laser (XFEL). Colloidal crystals were pumped with an infrared laser at a wavelength of 800 nm with varying power and probed by XFEL pulses at an energy of 8 keV with a time delay up to 1000 ps. The positions of the Bragg peaks, and their radial and azimuthal widths were analyzed as a function of the time delay. The spectral analysis of the data did not reveal significant enhancement of frequencies expected in this experiment. This allowed us to conclude that the amplitude of vibrational modes excited in colloidal crystals was less than the systematic error caused by the noise level. Full article

(This article belongs to the Special Issue X-Ray Free-Electron Laser)

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11 pages, 793 KiB

Open AccessArticle

Joint Resource Allocation in Secure OFDMA-Based Networks Taking a Base Station as a Two-Way Relay

by Ning Du^1,2,*, Fasheng Liu¹ and Yan Zang¹

¹ College of Electrical Engineering and Automation, Shandong University of Science and Technology, Qingdao 266590, China

² Department of Mathematics and Information Engineering, Dongchang College of Liaocheng University, Liaocheng 252000, China

Appl. Sci. 2017, 7(5), 520; https://doi.org/10.3390/app7050520 - 21 May 2017

Cited by 1 | Viewed by 4138

Abstract

Due to the broadcast nature of wireless media, all nodes in the coverage of a transmitter are capable of capturing its signals, thus wireless transmission is sensitive to wiretapping. Several existing schemes place an emphasis on secrecy rate improvement, under the protocols of [...] Read more.

Due to the broadcast nature of wireless media, all nodes in the coverage of a transmitter are capable of capturing its signals, thus wireless transmission is sensitive to wiretapping. Several existing schemes place an emphasis on secrecy rate improvement, under the protocols of amplify-and-forward or decode-and-forward, when there are only relay users in the network. We set up a novel communication model in which normal and two-way relay users coexist in the same cell, taking the base station as a relay. Our objective is to maximize the total secrecy rate, taking subcarrier pairing, subcarrier assignment and power allocation into account, when there is one eavesdropper in one cell of the cellular network. Although this problem is very intricate, we reformulate it as a convex optimization problem by means of Lagrange duality. In order to reduce the computational complexity, equal power allocation is proposed. Lastly, the experimental results show the proposed resource allocation scheme can obtain a higher secrecy rate than traditional schemes. Full article

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16 pages, 242 KiB

Open AccessReview

The Role of the Cerebellum in Unconscious and Conscious Processing of Emotions: A Review

by Silvia Clausi^1,2, Claudia Iacobacci^1,2,3, Michela Lupo¹, Giusy Olivito^1,4, Marco Molinari⁵ and Maria Leggio^1,2,*

¹ Ataxia Laboratory, IRCCS Santa Lucia Foundation, Via Ardeatina 306, 00179 Rome, Italy

² Department of Psychology, Sapienza University of Rome, Via dei Marsi 78, 00185 Rome, Italy

³ Ph.D. Program in Behavioral Neuroscience, Sapienza University of Rome, Via dei Marsi 78, 00185 Rome, Italy

⁴ Neuroimaging Laboratory, Santa Lucia Foundation, Via Ardeatina 306, 00179 Rome, Italy

⁵ Neurorehabilitation 1 and Spinal Center, Robotic Neurorehabilitation Lab, IRCCS Santa Lucia Foundation, Via Ardeatina 306, 00179 Rome, Italy

Appl. Sci. 2017, 7(5), 521; https://doi.org/10.3390/app7050521 - 17 May 2017

Cited by 47 | Viewed by 17102

Abstract

Studies from the past three decades have demonstrated that there is cerebellar involvement in the emotional domain. Emotional processing in humans requires both unconscious and conscious mechanisms. A significant amount of evidence indicates that the cerebellum is one of the cerebral structures that [...] Read more.

Studies from the past three decades have demonstrated that there is cerebellar involvement in the emotional domain. Emotional processing in humans requires both unconscious and conscious mechanisms. A significant amount of evidence indicates that the cerebellum is one of the cerebral structures that subserve emotional processing, although conflicting data has been reported on its function in unconscious and conscious mechanisms. This review discusses the available clinical, neuroimaging, and neurophysiological data on this issue. We also propose a model in which the cerebellum acts as a mediator between the internal state and external environment for the unconscious and conscious levels of emotional processing. Full article

(This article belongs to the Special Issue Sub- and Unconscious Information Processing in the Human Brain)

12 pages, 5758 KiB

Open AccessArticle

Intensified Pozzolanic Reaction on Kaolinite Clay-Based Mortar

by Yang-Hee Kwon¹, Sung-Hoon Kang^1,2, Sung-Gul Hong^1,* and Juhyuk Moon^2,*

¹ Department of Architecture & Architectural Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Korea

² Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576, Singapore

Appl. Sci. 2017, 7(5), 522; https://doi.org/10.3390/app7050522 - 18 May 2017

Cited by 33 | Viewed by 6453

Abstract

The objective of this study is to develop and characterize kaolinite clay-based structural mortar. The pozzolanic reaction induced from two mineral additives, i.e., calcium hydroxide and silica fume (SF), and the physical filling effect from SF, were found to be effective on the [...] Read more.

The objective of this study is to develop and characterize kaolinite clay-based structural mortar. The pozzolanic reaction induced from two mineral additives, i.e., calcium hydroxide and silica fume (SF), and the physical filling effect from SF, were found to be effective on the enhancement of structural properties. Based on several preliminary experiments, 7:3 ratio of kaolinite clay/calcium hydroxide was selected as a basic binder. Then, the amount of SF was chosen as 0%, 7.5%, and 15% of the total binder to consider both the chemical and physical effects. The results showed that compressive strengths of samples with 7.5% and 15% SF are significantly increased by approximately 200% and 350%, respectively, at 28 days compared to the sample without SF. However, based on the results of the sample with 15% SF, it is found that excessive addition of SF causes long-term strength loss, possibly owing to micro cracks. With the careful consideration on this long-term behavior, this suggested new mix design can be further extended to develop sustainable structural materials using natural minerals or waste materials with nonbinding properties. Full article

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10 pages, 996 KiB

Open AccessReview

Adhesion Promoters in Bituminous Road Materials: A Review

by Cesare Oliviero Rossi^1,*, Bagdat Teltayev²

and Ruggero Angelico^3,4

¹ Department of Chemistry and Chemical Technologies, University of Calabria, Arcavacata di Rende (CS) 87036, Italy

² Kazakhstan Highway Research Institute, Almaty 050061, Kazakhstan

³ Department of Agricultural, Environmental and Food Sciences (DIAAA), University of Molise, Via De Sanctis, Campobasso (CB) 86100, Italy

⁴ CSGI (Center for Colloid and Surface Science), Via della Lastruccia 3, Sesto Fiorentino (FI) I-50019, Italy

Appl. Sci. 2017, 7(5), 524; https://doi.org/10.3390/app7050524 - 18 May 2017

Cited by 65 | Viewed by 12124

Abstract

This review focuses on certain classes of organic compounds known variously in the specific literature of asphalt as adhesion promoters, antistripping agents, wetting agents, antistrips, or adhesion agents. These kinds of organic additives are currently formulated to enhance the bitumen coating of mineral [...] Read more.

This review focuses on certain classes of organic compounds known variously in the specific literature of asphalt as adhesion promoters, antistripping agents, wetting agents, antistrips, or adhesion agents. These kinds of organic additives are currently formulated to enhance the bitumen coating of mineral aggregates and improve the workability of asphalt mixtures. In this review, the term “adhesion promoters” includes both synthetic organic compounds as well as those extracted from natural resources, mixed in trace amounts to bitumen. Their main role is to alter the interfacial energy, so that the presence of water, even in trace, does not weaken the bitumen-aggregate bond and tends to favor adhesion. The report also considers the chemical functionalities that play a predominant role in bonding, as well as the effects of surface modification of the aggregate due to the presence of adhesion promoters in pre-blended bituminous mixtures. Although bitumen is widely used in road pavement construction and the discussion is mainly addressed to the improvement of adhesion in road materials, adhesion and wetting properties can also represent a general issue in various bitumen-based industrial products. Full article

(This article belongs to the Section Materials Science and Engineering)

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20 pages, 4745 KiB

Open AccessArticle

Combined Operation of Electrical Loads, Air Conditioning and Photovoltaic-Battery Systems in Smart Houses

by Roberto Romano¹, Pierluigi Siano^1,*

, Mariano Acone¹ and Vincenzo Loia²

¹ Dept. Industrial Engineering, University of Salerno, Fisciano (SA) 84084, Italy

² Dept. Management & Innovation Systems, University of Salerno, Fisciano (SA) 84084, Italy

Appl. Sci. 2017, 7(5), 525; https://doi.org/10.3390/app7050525 - 18 May 2017

Cited by 10 | Viewed by 5209

Abstract

In this paper, a novel Energy Management System (EMS) is proposed for a hybrid energy system with photovoltaic (PV) and energy storage system for a smart house. The EMS is designed to control the shiftable loads, the air conditioning and the electric storage [...] Read more.

In this paper, a novel Energy Management System (EMS) is proposed for a hybrid energy system with photovoltaic (PV) and energy storage system for a smart house. The EMS is designed to control the shiftable loads, the air conditioning and the electric storage system. The aim is to reduce the electrical energy consumption cost without compromising the end-user comfort. Monte Carlo Simulation (MCS) is used to estimate the optimal size of the hybrid system considering energy saving and investment costs. Simulations results confirm the effectiveness of the proposed EMS in decreasing the electrical energy consumption and costs. The proposed method for the sizing of the hybrid system is also able to select the best size of the PV-battery system in smart houses. Full article

(This article belongs to the Special Issue Smart Home and Energy Management Systems)

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12 pages, 5328 KiB

Open AccessArticle

Application of Pulsed Laser-TIG Hybrid Heat Source in Root Welding of Thick Plate Titanium Alloys

by Jipeng Shi, Yanbin Zhou and Liming Liu^*

Key Laboratory of Liaoning Advanced Welding and Joining Technology, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, China

Appl. Sci. 2017, 7(5), 527; https://doi.org/10.3390/app7050527 - 18 May 2017

Cited by 20 | Viewed by 6861

Abstract

Laser-TIG (tungsten inert gas) hybrid welding process is applied to produce stable back beads in the first layer during one-side multilayer welding. To explain why stable back beads can be formed, a comparison is conducted between single TIG and laser-TIG hybrid welding. Results [...] Read more.

Laser-TIG (tungsten inert gas) hybrid welding process is applied to produce stable back beads in the first layer during one-side multilayer welding. To explain why stable back beads can be formed, a comparison is conducted between single TIG and laser-TIG hybrid welding. Results indicate that during laser action the arc column is enhanced and deflected to the keyhole, which changes the spatial distribution of plasma by strong attraction. The keyhole plasma possesses extreme electric conductivity. After laser action, the enhanced arc is restituted, the low energy density arc acts on the molten pool, and the bottom of the molten pool is solidified to prevent its collapse. The heat and force are redistributed over the top of molten pool under the alternative action of the enhanced arc and original arc. In this case the thermal distribution and mechanical situation in the molten pool must be more balanced and reasonable, and the back bead appearance is continuous, stable and uniform. This process gives high quality and efficient root welding of the thick plate. Full article

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25 pages, 28908 KiB

Open AccessArticle

Artwork Identification for 360-Degree Panoramic Images Using Polyhedron-Based Rectilinear Projection and Keypoint Shapes

by Xun Jin¹ and Jongweon Kim^2,*

¹ Department of Copyright Protection, Sangmyung University, Seoul 03016, Korea

² Department of Electronics Engineering, Sangmyung University, Seoul 03016, Korea

Appl. Sci. 2017, 7(5), 528; https://doi.org/10.3390/app7050528 - 19 May 2017

Cited by 7 | Viewed by 9523

Abstract

With the increased development of 360-degree production technologies, artwork has recently been photographed without authorization. To prevent this infringement, we propose an artwork identification methodology for 360-degree images. We transform the 360-degree image into a three-dimensional sphere and wrap it with a polyhedron. [...] Read more.

With the increased development of 360-degree production technologies, artwork has recently been photographed without authorization. To prevent this infringement, we propose an artwork identification methodology for 360-degree images. We transform the 360-degree image into a three-dimensional sphere and wrap it with a polyhedron. On the sphere, several points are located on the polyhedron to determine the width, height, and direction of the rectilinear projection. The 360-degree image is divided and transformed into several rectilinear projected images to reduce the adverse effects from the distorted panoramic image. We also propose a method for improving the identification precision of artwork located at a highly distorted position using the difference of keypoint shapes. After applying the proposed methods, identification precision is increased by 45% for artwork that is displayed on a 79-inch monitor in a seriously distorted position with features that were generated by scale-invariant feature transformations. Full article

(This article belongs to the Special Issue Holography and 3D Imaging: Tomorrows Ultimate Experience)

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11 pages, 3114 KiB

Open AccessArticle

X-ray Pump–Probe Investigation of Charge and Dissociation Dynamics in Methyl Iodine Molecule

by Li Fang^1,*, Hui Xiong², Edwin Kukk³ and Nora Berrah^2,*

¹ Center for High Energy Density Science, University of Texas, Austin, TX 78712, USA

² Department of Physics, University of Connecticut, Storrs, CT 06269, USA

³ Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland

Appl. Sci. 2017, 7(5), 529; https://doi.org/10.3390/app7050529 - 19 May 2017

Cited by 9 | Viewed by 6087

Abstract

Molecular dynamics is of fundamental interest in natural science research. The capability of investigating molecular dynamics is one of the various motivations for ultrafast optics. We present our investigation of photoionization and nuclear dynamics in methyl iodine (CH₃I) molecule with an [...] Read more.

Molecular dynamics is of fundamental interest in natural science research. The capability of investigating molecular dynamics is one of the various motivations for ultrafast optics. We present our investigation of photoionization and nuclear dynamics in methyl iodine (CH₃I) molecule with an X-ray pump X-ray probe scheme. The pump–probe experiment was realized with a two-mirror X-ray split and delay apparatus. Time-of-flight mass spectra at various pump–probe delay times were recorded to obtain the time profile for the creation of high charge states via sequential ionization and for molecular dissociation. We observed high charge states of atomic iodine up to 29+, and visualized the evolution of creating these high atomic ion charge states, including their population suppression and enhancement as the arrival time of the second X-ray pulse was varied. We also show the evolution of the kinetics of the high charge states upon the timing of their creation during the ionization-dissociation coupled dynamics. We demonstrate the implementation of X-ray pump–probe methodology for investigating X-ray induced molecular dynamics with femtosecond temporal resolution. The results indicate the footprints of ionization that lead to high charge states, probing the long-range potential curves of the high charge states. Full article

(This article belongs to the Special Issue X-Ray Free-Electron Laser)

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14 pages, 3320 KiB

Open AccessArticle

Innovation of New Occlusion Devices for Cancers

by Hao-Ming Hsiao^*, Tzu-Yuan Lin, Chien-Erh Lin, Han-Yu Lee and Yi-Ping Wang

Department of Mechanical Engineering, National Taiwan University, Taipei 10617, Taiwan

Appl. Sci. 2017, 7(5), 530; https://doi.org/10.3390/app7050530 - 19 May 2017

Cited by 1 | Viewed by 5688

Abstract

Liver cancer, a life-threatening disease, can be cured if found early. A common treatment for liver tumors that cannot be removed by surgery is hepatic artery embolization. It involves injecting small beads to block the blood flow towards cancer cells. In this paper, [...] Read more.

Liver cancer, a life-threatening disease, can be cured if found early. A common treatment for liver tumors that cannot be removed by surgery is hepatic artery embolization. It involves injecting small beads to block the blood flow towards cancer cells. In this paper, we propose the world’s first nitinol spherical occlusion device, which can be deployed in the upstream of an artery to reduce the blood flow to the downstream cancer cells. Finite element models were developed to predict the device’s mechanical integrity during manufacturing and deployment. Computational fluid dynamics were applied to simulate the device’s clinical occlusion performance. Simulation results suggested that devices with a metal density of 14–27% would reduce the average blood flow rate by 30–50%. A conceptual prototype was first cut by pulsed-fiber optic laser, and a series of expansions and heat treatments were used to shape the device to its final geometry. Flow experiments were conducted for proof of concept, and results showed that the spherical occlusion device successfully reduced the flow as designed. The occlusion device with the metal density of 27% was able to reduce 44% of flow, which agreed well with the simulation results. Full article

(This article belongs to the Special Issue Selected Papers from the 2016 International Conference on Inventions)

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14 pages, 3016 KiB

Open AccessReview

Molecular Dynamics of XFEL-Induced Photo-Dissociation, Revealed by Ion-Ion Coincidence Measurements

by Edwin Kukk^1,*, Koji Motomura², Hironobu Fukuzawa^2,4, Kiyonobu Nagaya^3,4 and Kiyoshi Ueda^2,4

¹ Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland

² Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan

³ Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan

⁴ RIKEN Spring-8 Center, Sayo, Hyogo 679-5148, Japan

Appl. Sci. 2017, 7(5), 531; https://doi.org/10.3390/app7050531 - 19 May 2017

Cited by 21 | Viewed by 6607

Abstract

X-ray free electron lasers (XFELs) providing ultrashort intense pulses of X-rays have proven to be excellent tools to investigate the dynamics of radiation-induced dissociation and charge redistribution in molecules and nanoparticles. Coincidence techniques, in particular multi-ion time-of-flight (TOF) coincident experiments, can provide detailed [...] Read more.

X-ray free electron lasers (XFELs) providing ultrashort intense pulses of X-rays have proven to be excellent tools to investigate the dynamics of radiation-induced dissociation and charge redistribution in molecules and nanoparticles. Coincidence techniques, in particular multi-ion time-of-flight (TOF) coincident experiments, can provide detailed information on the photoabsorption, charge generation, and Coulomb explosion events. Here we review several such recent experiments performed at the SPring-8 Angstrom Compact free electron LAser (SACLA) facility in Japan, with iodomethane, diiodomethane, and 5-iodouracil as targets. We demonstrate how to utilize the momentum-resolving capabilities of the ion TOF spectrometers to resolve and filter the coincidence data and extract various information essential in understanding the time evolution of the processes induced by the XFEL pulses. Full article

(This article belongs to the Special Issue X-Ray Free-Electron Laser)

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19 pages, 1396 KiB

Open AccessReview

Surround by Sound: A Review of Spatial Audio Recording and Reproduction

by Wen Zhang^1,2,*, Parasanga N. Samarasinghe¹, Hanchi Chen¹ and Thushara D. Abhayapala¹

¹ Research School of Engineering, College of Engineering and Computer Science, The Australian National University, Canberra 2601 ACT, Australia

² Center of Intelligent Acoustics and Immersive Communications, Northwestern Polytechnical University, 127 Youyi West Road, Xi’an 710072, Shaanxi, China

Appl. Sci. 2017, 7(5), 532; https://doi.org/10.3390/app7050532 - 20 May 2017

Cited by 102 | Viewed by 22964

Abstract

In this article, a systematic overview of various recording and reproduction techniques for spatial audio is presented. While binaural recording and rendering is designed to resemble the human two-ear auditory system and reproduce sounds specifically for a listener’s two ears, soundfield recording and [...] Read more.

In this article, a systematic overview of various recording and reproduction techniques for spatial audio is presented. While binaural recording and rendering is designed to resemble the human two-ear auditory system and reproduce sounds specifically for a listener’s two ears, soundfield recording and reproduction using a large number of microphones and loudspeakers replicate an acoustic scene within a region. These two fundamentally different types of techniques are discussed in the paper. A recent popular area, multi-zone reproduction, is also briefly reviewed in the paper. The paper is concluded with a discussion of the current state of the field and open problems. Full article

(This article belongs to the Special Issue Spatial Audio)

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