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Appl. Sci., Volume 9, Issue 7 (April-1 2019)

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Cover Story (view full-size image) Flow-diverting stents show considerable promise for the treatment of cerebral aneurysms. [...] Read more.
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Open AccessArticle
Multi Objective for PMU Placement in Compressed Distribution Network Considering Cost and Accuracy of State Estimation
Appl. Sci. 2019, 9(7), 1515; https://doi.org/10.3390/app9071515
Received: 26 March 2019 / Revised: 4 April 2019 / Accepted: 10 April 2019 / Published: 11 April 2019
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Abstract
A phasor measurement unit (PMU) can provide phasor measurements to the distribution network to improve observability. Based on pre-configuration and existing measurements, a network compression method is proposed to reduce PMU candidate locations. Taking the minimum number of PMUs and the lowest state [...] Read more.
A phasor measurement unit (PMU) can provide phasor measurements to the distribution network to improve observability. Based on pre-configuration and existing measurements, a network compression method is proposed to reduce PMU candidate locations. Taking the minimum number of PMUs and the lowest state estimation error as the objective functions and taking full observability of distribution network as the constraint, a multi objective model of optimal PMU placement (OPP) is proposed. A hybrid state estimator based on supervisory control and data acquisition (SCADA) and PMU measurements is proposed. To reduce the number of PMUs required for full observability, SCADA measurement data are also considered into the constraint by update and equivalent. In addition, a non-dominated sorting genetic algorithm-II (NSGA-II) is applied to solve the model to get the Pareto set. Finally, the optimal solution is selected from the Pareto set by the technique for order preference by similarity to ideal solution (TOPSIS). The effectiveness of the proposed method is verified by IEEE standard bus systems. Full article
(This article belongs to the Special Issue Energy Management and Smart Grids)
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Open AccessArticle
Effectiveness of Collagen Membrane in the Treatment of Schneiderian Membrane Perforation
Appl. Sci. 2019, 9(7), 1514; https://doi.org/10.3390/app9071514
Received: 5 March 2019 / Revised: 1 April 2019 / Accepted: 10 April 2019 / Published: 11 April 2019
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Abstract
Schneiderian membrane perforation (SMP) is the most common complication encountered during sinus lift procedures. SMPs should be managed to prevent loss of the valuable bone graft and bone substitute materials. A fast-resorbing collagen membrane (CM) is a soft, white, pliable, and nonfriable sponge [...] Read more.
Schneiderian membrane perforation (SMP) is the most common complication encountered during sinus lift procedures. SMPs should be managed to prevent loss of the valuable bone graft and bone substitute materials. A fast-resorbing collagen membrane (CM) is a soft, white, pliable, and nonfriable sponge used in dental surgery. The purpose of this study was to evaluate the clinical outcomes of SMP repair using CMs when an SMP had occurred during a sinus lifting procedure. The patients were divided into three groups according to the size of the SMPs during the sinus lift procedure. (A) Group 1: there was no perforation of the Schneiderian membrane but the membrane was weakened (or thinned) and repaired using CMs. (B) Group 2: the SMP was small to medium in size (< 10 mm) and repaired using CMs and fibrin adhesive (FA). (C) Group 3: the SMP was large in size (> 10 mm) and repaired using a collagen plug. The negative control group consisted of patients who did not have any SMP (Control) and these patients were randomly selected. Orthopantomographic X-rays taken before surgery, 2–3 days following surgery, and over 6 months after surgery (follow-up) were used to evaluate the acquired bone height according to groups. Bone heights were measured from the crestal bone at the planned implant placement sites. Clinical outcomes, including implant success and complications according to repair method, were also investigated. There was no significant difference in bone heights between the groups with the exception of group 3. The overall implant survival rate was 100% for implants placed in sinuses with frank SMPs or weakened sinus membranes. The CM is applicable for small-to-moderate perforations or sinus membranes which have been weakened or thinned during sinus lift procedures. Full article
(This article belongs to the Special Issue Development of Membranes for Oral and Maxillofacial Application)
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Open AccessArticle
Packet Switching Strategy and Node Architecture of Extended Spectral-Amplitude-Coding Labels in GMPLS Networks
Appl. Sci. 2019, 9(7), 1513; https://doi.org/10.3390/app9071513
Received: 31 January 2019 / Revised: 5 April 2019 / Accepted: 8 April 2019 / Published: 11 April 2019
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Abstract
We present packet switching applications based on extended spectral-amplitude-coding (SAC) labels in generalized multi-protocol label switching (GMPLS) networks. The proposed approach combines the advantages of wavelength-division multiplexing (WDM) and optical code-division multiple access (OCDMA). The extended SAC labels preserve the orthogonal property to [...] Read more.
We present packet switching applications based on extended spectral-amplitude-coding (SAC) labels in generalized multi-protocol label switching (GMPLS) networks. The proposed approach combines the advantages of wavelength-division multiplexing (WDM) and optical code-division multiple access (OCDMA). The extended SAC labels preserve the orthogonal property to avoid the effect of multiple access interference (MAI) shown at the decoder. We investigate the node architecture of label generation/recognition based on arrayed waveguide grating (AWG). Combining cyclic-shifted maximal length sequence (MLS) codes with the wavelength routed property of AWG simplifies the node structure. The simulation results show that the proposed labels achieve good performances against receiver noise due to the low average cross-correlation values. Under a given bit-error-rate (BER), the switching efficiency of the extended SAC labels outperforms the previous OCDMA schemes, as the network nodes are capable of processing a large number of labels simultaneously. Full article
(This article belongs to the Special Issue Photonic Switching)
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Open AccessArticle
Simulation Research on the Time-Varying Meshing Stiffness and Vibration Response of Micro-Cracks in Gears under Variable Tooth Shape Parameters
Appl. Sci. 2019, 9(7), 1512; https://doi.org/10.3390/app9071512
Received: 6 March 2019 / Revised: 31 March 2019 / Accepted: 3 April 2019 / Published: 11 April 2019
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Abstract
The gear is one of the important parts of a rotary gearbox. Once catastrophic gear failure occurs, it will cause a great threat to production and life safety. The crack is an important failure factor causing changes in time-varying stiffness and vibration response. [...] Read more.
The gear is one of the important parts of a rotary gearbox. Once catastrophic gear failure occurs, it will cause a great threat to production and life safety. The crack is an important failure factor causing changes in time-varying stiffness and vibration response. It is difficult to effectively identify the vibration response and meshing stiffness changes when there is a fine crack in the gear. Therefore, it is of great importance to improve the accuracy of meshing stiffness calculation and dynamic simulations under micro-cracks. Investigations of meshing stiffness and the vibration response of a gearbox is almost all about fixed gear shape parameters. However, the actual production process of gear system needs to change gear shape parameters. In this paper, the meshing stiffness and vibration response of the dynamic simulation signals of gear teeth with different crack depths at different tooth shape parameters (the pressure angle, the modulus, and the tooth number) were calculated, respectively. The influence of cracks on the vibration response was investigated by the fault detection indicators, the Root Mean Square (RMS), the kurtosis, and the crest factor. The result shows that when the pressure angle and modulus change, the vibration response changes erratically. However, when the tooth numbers change, the vibration response changes regularly. The results could be a guide for choosing gears in different shape parameters when system stability is the aim. Full article
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Open AccessReview
Solution-Based Synthesis and Processing of Metal Chalcogenides for Thermoelectric Applications
Appl. Sci. 2019, 9(7), 1511; https://doi.org/10.3390/app9071511
Received: 2 March 2019 / Revised: 27 March 2019 / Accepted: 3 April 2019 / Published: 11 April 2019
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Abstract
Metal chalcogenide materials are current mainstream thermoelectric materials with high conversion efficiency. This review provides an overview of the scalable solution-based methods for controllable synthesis of various nanostructured and thin-film metal chalcogenides, as well as their properties for thermoelectric applications. Furthermore, the state-of-art [...] Read more.
Metal chalcogenide materials are current mainstream thermoelectric materials with high conversion efficiency. This review provides an overview of the scalable solution-based methods for controllable synthesis of various nanostructured and thin-film metal chalcogenides, as well as their properties for thermoelectric applications. Furthermore, the state-of-art ink-based processing method for fabrication of thermoelectric generators based on metal chalcogenides is briefly introduced. Finally, the perspective on this field with regard to material production and device development is also commented upon. Full article
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Open AccessArticle
A Novel Independently Biased 3-Stack GaN HEMT Configuration for Efficient Design of Microwave Amplifiers
Appl. Sci. 2019, 9(7), 1510; https://doi.org/10.3390/app9071510
Received: 12 February 2019 / Revised: 19 March 2019 / Accepted: 8 April 2019 / Published: 11 April 2019
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Abstract
The power amplifier (PA) and low-noise amplifier (LNA) are the most critical components of transceiver systems including radar, mobile communications, satellite communications, etc. While the PA is the key component of the transmitter (TX), the LNA is the key component of the receiver [...] Read more.
The power amplifier (PA) and low-noise amplifier (LNA) are the most critical components of transceiver systems including radar, mobile communications, satellite communications, etc. While the PA is the key component of the transmitter (TX), the LNA is the key component of the receiver (RX) of the transceiver system. It is pointed out that traditional design approaches for both the LNA and PA face challenging drawbacks. When designing an LNA, the power gain and noise figure of the LNA are difficult to improve simultaneously. For PA design, it indicates that efficiency and linearity of the PA are also hard to improve simultaneously. This study aims to surmount this by proposing a novel independently biased 3-stack GaN high-electron-mobility transistor (HEMT) configuration for efficient design of both PA and LNA for next generation wireless communication systems. By employing an independently biased technique, the proposed configuration can offer superior performance at both small-signal (SS) for LNA design and large-signal (LS) for PA design compared with other typical circuit configurations. Simulation results show that by utilizing an adaptive bias control of each transistor of the proposed configuration, both power gain and noise figure can be improved simultaneously for the LNA design. Moreover, efficiency and linearity can be also improved at the same time for the PA design. Compared results with other typical configurations including a single-stage, conventional cascode, independently biased cascode, and conventional 3-stack reveals that the proposed configuration exhibits superior advantages at both SS and LS operation. Full article
(This article belongs to the Section Electrical, Electronics and Communications Engineering)
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Open AccessArticle
Extraction Efficiency of a Commercial Espresso Machine Compared to a Stainless-Steel Column Pressurized Hot Water Extraction (PHWE) System for the Determination of 23 Pharmaceuticals, Antibiotics and Hormones in Sewage Sludge
Appl. Sci. 2019, 9(7), 1509; https://doi.org/10.3390/app9071509
Received: 26 February 2019 / Revised: 20 March 2019 / Accepted: 4 April 2019 / Published: 11 April 2019
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Abstract
Two green chemistry extraction systems, an in-house stainless-steel column Pressurized Hot Water Extraction system (PHWE) and a commercially available Espresso machine were applied for analysing 23 active pharmaceutical ingredients (APIs) in sewage sludge. Final analysis was performed on UPLC-MS/MS using two different chromatographic [...] Read more.
Two green chemistry extraction systems, an in-house stainless-steel column Pressurized Hot Water Extraction system (PHWE) and a commercially available Espresso machine were applied for analysing 23 active pharmaceutical ingredients (APIs) in sewage sludge. Final analysis was performed on UPLC-MS/MS using two different chromatographic methods: acid and basic. When analysing all 23 APIs in sewage sludge both extraction methods showed good repeatability. The PHWE method allowed for a more complete extraction of APIs that were more tightly bound to the matrix, as exemplified by much higher concentrations of e.g., ketoconazole, citalopram and ciprofloxacin. In total, 19 out of 23 investigated APIs were quantified in sewage sludge, and with a few exceptions the PHWE method was more exhaustive. Mean absolute recoveries of 7 spiked labelled APIs were lower for the PHWE method than the Espresso method. Under acid chromatographic conditions mean recoveries were 16% and 24%, respectively, but increased to 24% and 37% under basic conditions. The difference between the PHWE method and the Espresso method might be interpreted as the Espresso method giving higher extraction efficiency; however, TIC scans of extracts revealed a much higher matrix co-extraction for the PHWE method. Attempts were made to correlate occurrence of compounds in sewage sludge with chemical properties of the 23 APIs and there are strong indications that both the number of aromatic rings and the presence of a positive charge is important for the sorption processes to sewage sludge. Full article
(This article belongs to the Special Issue Environmental Fate of Emerging Organic Micro-Contaminants)
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Open AccessArticle
Leg Trajectory Planning for Quadruped Robots with High-Speed Trot Gait
Appl. Sci. 2019, 9(7), 1508; https://doi.org/10.3390/app9071508
Received: 14 March 2019 / Revised: 7 April 2019 / Accepted: 9 April 2019 / Published: 11 April 2019
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Abstract
In this paper, a single leg platform for quadruped robots is designed based on the motivation of high-speed locomotion. The leg is designed for lightweight and low inertia with a structure of three joints by imitating quadruped animals. Because high acceleration and extensive [...] Read more.
In this paper, a single leg platform for quadruped robots is designed based on the motivation of high-speed locomotion. The leg is designed for lightweight and low inertia with a structure of three joints by imitating quadruped animals. Because high acceleration and extensive loadings will be involved on the legs during the high-speed locomotion, the trade-off between the leg mass and strength is specifically designed and evaluated with the finite element analysis. Moreover, quadruped animals usually increase stride frequency and decrease contact time as the locomotion speed increases, while maintaining the swing duration during trot gait. Inspired by this phenomenon, the foot-end trajectory for quadruped robots with a high-speed trot gait is proposed. The gait trajectory is planned for swing and stance phase; thus the robot can keep its stability with adjustable trajectories while following a specific gait pattern. Especially for the swing phase, the proposed trajectory can minimize the maximum acceleration of legs and ensure the continuity of position, speed, and acceleration. Then, based on the kinematics analysis, the proposed trajectory is compared with the trajectory of Bézier curve for the power consumption. Finally, a simulation with Webots software is carried out for verifying the motion stability with two trajectory planning schemes respectively. Moreover, a motion capture device is used for evaluating the tracking accuracy of two schemes for obtaining an optimal gait trajectory suitable for high-speed trot gait. Full article
(This article belongs to the Special Issue Advances in Mechanical Systems Dynamics)
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Open AccessArticle
Low Frequency Sound Absorption by Optimal Combination Structure of Porous Metal and Microperforated Panel
Appl. Sci. 2019, 9(7), 1507; https://doi.org/10.3390/app9071507
Received: 18 March 2019 / Revised: 8 April 2019 / Accepted: 8 April 2019 / Published: 11 April 2019
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Abstract
The combination structure of a porous metal and microperforated panel was optimized to develop a low frequency sound absorber. Theoretical models were constructed by the transfer matrix method based on the Johnson—Champoux—Allard model and Maa’s theory. Parameter optimizations of the sound absorbers were [...] Read more.
The combination structure of a porous metal and microperforated panel was optimized to develop a low frequency sound absorber. Theoretical models were constructed by the transfer matrix method based on the Johnson—Champoux—Allard model and Maa’s theory. Parameter optimizations of the sound absorbers were conducted by Cuckoo search algorithm. The sound absorption coefficients of the combination structures were verified by finite element simulation and validated by standing wave tube measurement. The experimental data was consistent with the theoretical and simulation data, which proved the efficiency, reliability, and accuracy of the constructed theoretical sound absorption model and finite element model. The actual average sound absorption coefficient of the microperforated panel + cavity + porous metal + cavity sound absorber in the 100–1800 Hz range reached 62.9615% and 73.5923%, respectively, when the limited total thickness was 30 mm and 50 mm. The excellent low frequency sound absorbers obtained can be used in the fields of acoustic environmental protection and industrial noise reduction. Full article
(This article belongs to the Section Civil Engineering)
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Open AccessArticle
IMU-Aided High-Frequency Lidar Odometry for Autonomous Driving
Appl. Sci. 2019, 9(7), 1506; https://doi.org/10.3390/app9071506
Received: 14 March 2019 / Revised: 3 April 2019 / Accepted: 6 April 2019 / Published: 11 April 2019
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Abstract
For autonomous driving, it is important to obtain precise and high-frequency localization information. This paper proposes a novel method in which the Inertial Measurement Unit (IMU), wheel encoder, and lidar odometry are utilized together to estimate the ego-motion of an unmanned ground vehicle. [...] Read more.
For autonomous driving, it is important to obtain precise and high-frequency localization information. This paper proposes a novel method in which the Inertial Measurement Unit (IMU), wheel encoder, and lidar odometry are utilized together to estimate the ego-motion of an unmanned ground vehicle. The IMU is fused with the wheel encoder to obtain the motion prior, and it is involved in three levels of the lidar odometry: Firstly, we use the IMU information to rectify the intra-frame distortion of the lidar scan, which is caused by the vehicle’s own movement; secondly, the IMU provides a better initial guess for the lidar odometry; and thirdly, the IMU is fused with the lidar odometry in an Extended Kalman filter framework. In addition, an efficient method for hand–eye calibration between the IMU and the lidar is proposed. To evaluate the performance of our method, extensive experiments are performed and our system can output stable, accurate, and high-frequency localization results in diverse environment without any prior information. Full article
(This article belongs to the Special Issue Intelligent Processing on Image and Optical Information)
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Open AccessArticle
Discrimination between Modal, Breathy and Pressed Voice for Single Vowels Using Neck-Surface Vibration Signals
Appl. Sci. 2019, 9(7), 1505; https://doi.org/10.3390/app9071505
Received: 8 March 2019 / Revised: 4 April 2019 / Accepted: 6 April 2019 / Published: 11 April 2019
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Abstract
The purpose of this study was to investigate the feasibility of using neck-surface acceleration signals to discriminate between modal, breathy and pressed voice. Voice data for five English single vowels were collected from 31 female native Canadian English speakers using a portable Neck [...] Read more.
The purpose of this study was to investigate the feasibility of using neck-surface acceleration signals to discriminate between modal, breathy and pressed voice. Voice data for five English single vowels were collected from 31 female native Canadian English speakers using a portable Neck Surface Accelerometer (NSA) and a condenser microphone. Firstly, auditory-perceptual ratings were conducted by five clinically-certificated Speech Language Pathologists (SLPs) to categorize voice type using the audio recordings. Intra- and inter-rater analyses were used to determine the SLPs’ reliability for the perceptual categorization task. Mixed-type samples were screened out, and congruent samples were kept for the subsequent classification task. Secondly, features such as spectral harmonics, jitter, shimmer and spectral entropy were extracted from the NSA data. Supervised learning algorithms were used to map feature vectors to voice type categories. A feature wrapper strategy was used to evaluate the contribution of each feature or feature combinations to the classification between different voice types. The results showed that the highest classification accuracy on a full set was 82.5%. The breathy voice classification accuracy was notably greater (approximately 12%) than those of the other two voice types. Shimmer and spectral entropy were the best correlated metrics for the classification accuracy. Full article
(This article belongs to the Special Issue Computational Methods and Engineering Solutions to Voice)
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Open AccessArticle
Inter-Sentence Segmentation of YouTube Subtitles Using Long-Short Term Memory (LSTM)
Appl. Sci. 2019, 9(7), 1504; https://doi.org/10.3390/app9071504
Received: 18 January 2019 / Revised: 7 April 2019 / Accepted: 8 April 2019 / Published: 11 April 2019
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Abstract
Recently, with the development of Speech to Text, which converts voice to text, and machine translation, technologies for simultaneously translating the captions of video into other languages have been developed. Using this, YouTube, a video-sharing site, provides captions in many languages. Currently, the [...] Read more.
Recently, with the development of Speech to Text, which converts voice to text, and machine translation, technologies for simultaneously translating the captions of video into other languages have been developed. Using this, YouTube, a video-sharing site, provides captions in many languages. Currently, the automatic caption system extracts voice data when uploading a video and provides a subtitle file converted into text. This method creates subtitles suitable for the running time. However, when extracting subtitles from video using Speech to Text, it is impossible to accurately translate the sentence because all sentences are generated without periods. Since the generated subtitles are separated by time units rather than sentence units, and are translated, it is very difficult to understand the translation result as a whole. In this paper, we propose a method to divide text into sentences and generate period marks to improve the accuracy of automatic translation of English subtitles. For this study, we use the 27,826 sentence subtitles provided by Stanford University’s courses as data. Since this lecture video provides complete sentence caption data, it can be used as training data by transforming the subtitles into general YouTube-like caption data. We build a model with the training data using the LSTM-RNN (Long-Short Term Memory – Recurrent Neural Networks) and predict the position of the period mark, resulting in prediction accuracy of 70.84%. Our research will provide people with more accurate translations of subtitles. In addition, we expect that language barriers in online education will be more easily broken by achieving more accurate translations of numerous video lectures in English. Full article
(This article belongs to the Special Issue Selected Papers from IMETI 2018)
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Open AccessArticle
MIFT: A Moment-Based Local Feature Extraction Algorithm
Appl. Sci. 2019, 9(7), 1503; https://doi.org/10.3390/app9071503
Received: 12 February 2019 / Revised: 3 April 2019 / Accepted: 9 April 2019 / Published: 11 April 2019
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Abstract
We propose a local feature descriptor based on moment. Although conventional scale invariant feature transform (SIFT)-based algorithms generally use difference of Gaussian (DoG) for feature extraction, they remain sensitive to more complicated deformations. To solve this problem, we propose MIFT, an invariant feature [...] Read more.
We propose a local feature descriptor based on moment. Although conventional scale invariant feature transform (SIFT)-based algorithms generally use difference of Gaussian (DoG) for feature extraction, they remain sensitive to more complicated deformations. To solve this problem, we propose MIFT, an invariant feature transform algorithm based on the modified discrete Gaussian-Hermite moment (MDGHM). Taking advantage of MDGHM’s high performance to represent image information, MIFT uses an MDGHM-based pyramid for feature extraction, which can extract more distinctive extrema than the DoG, and MDGHM-based magnitude and orientation for feature description. We compared the proposed MIFT method performance with current best practice methods for six image deformation types, and confirmed that MIFT matching accuracy was superior of other SIFT-based methods. Full article
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Open AccessArticle
Development of a Data-Mining Technique for Regional-Scale Evaluation of Building Seismic Vulnerability
Appl. Sci. 2019, 9(7), 1502; https://doi.org/10.3390/app9071502
Received: 21 February 2019 / Revised: 27 March 2019 / Accepted: 3 April 2019 / Published: 11 April 2019
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Abstract
Assessing the seismic vulnerability of large numbers of buildings is an expensive and time-consuming task, requiring the collection of highly complex and multifaceted data on building characteristics and the use of sophisticated computational models. This study reports on the development of a data [...] Read more.
Assessing the seismic vulnerability of large numbers of buildings is an expensive and time-consuming task, requiring the collection of highly complex and multifaceted data on building characteristics and the use of sophisticated computational models. This study reports on the development of a data mining technique: Support Vector Machine (SVM) for resolving such multi-dimensional data problems for assessing buildings’ seismic vulnerability at a regional scale. Particularly, we developed an SVM model for rapid assessment of the macroscale seismic vulnerability of buildings in terms of spectral yield and ultimate points of their capacity curves. Two case studies, one with 11 building characteristics and the other with 20, were used to test the proposed SVM model. The results show that when 20 building characteristics are included, an individual building’s seismic vulnerability in term of its spectral yield and ultimate points can be predicted by the proposed SVM model with an average 64% accuracy if the training dataset contains 400 samples, rising to 74% with 4400 training samples. Coupling the proposed technique with demand curves based on buildings’ locations will enable rapid and reliable seismic-risk assessment at a regional scale, requiring only basic building characteristics rather than complex computational models. Full article
(This article belongs to the Section Civil Engineering)
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Open AccessArticle
The Influence of Chemical Component Distribution on the Radiometric Properties of Particle Aggregates
Appl. Sci. 2019, 9(7), 1501; https://doi.org/10.3390/app9071501
Received: 31 December 2018 / Revised: 26 March 2019 / Accepted: 6 April 2019 / Published: 11 April 2019
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Abstract
The radiometric properties, including the extinction efficiency, absorption efficiency, scattering efficiency, and asymmetric parameter values of particle aggregates consisting of multiple chemical components are critical in industry and nature. This article aims to analyze the influence of chemical component distribution on these radiometric [...] Read more.
The radiometric properties, including the extinction efficiency, absorption efficiency, scattering efficiency, and asymmetric parameter values of particle aggregates consisting of multiple chemical components are critical in industry and nature. This article aims to analyze the influence of chemical component distribution on these radiometric properties. The particle aggregates are generated by a diffusion-limited aggregate method by which spherical particles are stuck together randomly. The particle aggregates have two components with a major component of a fixed refractive index and a minor component of a changed refractive index. The radiometric properties are calculated using a multi-sphere T-matrix (MSTM) method for particle aggregates with different particle radii and with refractive indices, distributions of components, and volume fractions of the minor component. The results show that the chemical component distribution influences the radiometric properties of the particle aggregate. Evenly spreading the strong absorptive minor component into each particle, compared to concentrating it in a few particles, can raise the absorption efficiency, reduce the scattering efficiency, and ultimately reduce the extinction efficiency of the aggregate. For aggregates with major and minor components in different particles, a similar effect is shown when spreading the minor component particles evenly in the aggregate relative to gathering them in one part of the aggregate. Full article
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Open AccessArticle
Application of a Design and Construction Method Based on a Study of User Needs in the Prevention of Accidents Involving Operators of Demolition Robots
Appl. Sci. 2019, 9(7), 1500; https://doi.org/10.3390/app9071500
Received: 14 March 2019 / Revised: 5 April 2019 / Accepted: 5 April 2019 / Published: 11 April 2019
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Abstract
The paper presents a new method of design and construction aimed at developing a system that helps to prevent accidents involving demolition robot operators. The method is based on a study of user needs and was developed in accordance with Design Thinking methodology. [...] Read more.
The paper presents a new method of design and construction aimed at developing a system that helps to prevent accidents involving demolition robot operators. The method is based on a study of user needs and was developed in accordance with Design Thinking methodology. This study provides a theoretical review of designing processes and methodologies, including conceptual design, and explores the implementation of the proposed method in the designing process for a Human–Machine Interface (HMI) accident prevention system. An in-depth study of user needs combined with an analysis of the operational system, both of which followed the stages in the proposed method, as well as with experimental tests on a small remote control demolition robot, inspired the development of an operator-controlled HMI system. The theoretical review concerns non-haptic feedback devices, which can be implemented in the demolition robot remote control or in operator safety equipment. Experimental research helped to determine the data necessary to develop an HMI system that continuously uses information from sensors installed on the machine. The paper also addresses issues related to the implementation of the HMI interface in order to avoid failures resulting from robot misuse and to protect the operator from any hazards caused by potential accidents. This paper emphasizes the importance of the connection between man and machine to overcome the lack of direct information flow in the case of mechanical operation. Full article
(This article belongs to the Special Issue Accident Analysis and Prevention: Experimental & Numerical Approaches)
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Open AccessArticle
Partially Coherent Flat-Topped Beam Generated by an Axicon
Appl. Sci. 2019, 9(7), 1499; https://doi.org/10.3390/app9071499
Received: 23 March 2019 / Revised: 4 April 2019 / Accepted: 6 April 2019 / Published: 11 April 2019
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Abstract
The intensity distribution of a partially coherent beam with a nonconventional correlation function, named the multi-Gaussian Schell-model (MGSM) beam, focused by an axicon was investigated in detail. Our numerical results showed that an optical needle with a flat-topped spatial profile and long focal [...] Read more.
The intensity distribution of a partially coherent beam with a nonconventional correlation function, named the multi-Gaussian Schell-model (MGSM) beam, focused by an axicon was investigated in detail. Our numerical results showed that an optical needle with a flat-topped spatial profile and long focal depth was formed and that we can modulate the focal shift and focal depth of the optical needle by varying the width of the degree of coherence (DOC) and the parameters of the correlation function. The adjustable optical needle can be applied for electron acceleration, particle trapping, fiber coupling and percussion drilling. Full article
(This article belongs to the Special Issue Recent Advances in Statistical Optics and Plasmonics)
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Open AccessFeature PaperReview
Superfluids, Fluctuations and Disorder
Appl. Sci. 2019, 9(7), 1498; https://doi.org/10.3390/app9071498
Received: 1 March 2019 / Revised: 8 April 2019 / Accepted: 8 April 2019 / Published: 10 April 2019
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Abstract
We present a field-theory description of ultracold bosonic atoms in the presence of a disordered external potential. By means of functional integration techniques, we aim to investigate and review the interplay between disordered energy landscapes and fluctuations, both thermal and quantum ones. Within [...] Read more.
We present a field-theory description of ultracold bosonic atoms in the presence of a disordered external potential. By means of functional integration techniques, we aim to investigate and review the interplay between disordered energy landscapes and fluctuations, both thermal and quantum ones. Within the broken-symmetry phase, up to the Gaussian level of approximation, the disorder contribution crucially modifies both the condensate depletion and the superfluid response. Remarkably, it is found that the ordered (i.e., superfluid) phase can be destroyed also in regimes where the random external potential is suitable for a perturbative analysis. We analyze the simplest case of quenched disorder and then we move to present the implementation of the replica trick for ultracold bosonic systems. In both cases, we discuss strengths and limitations of the reviewed approach, paying specific attention to possible extensions and the most recent experimental outputs. Full article
(This article belongs to the Special Issue Quantum Optics for Fundamental Quantum Mechanics)
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Open AccessReview
Nanoplasmonic Sensor Based on Surface Plasmon-Coupled Emission: Review
Appl. Sci. 2019, 9(7), 1497; https://doi.org/10.3390/app9071497
Received: 14 November 2018 / Revised: 26 December 2018 / Accepted: 3 January 2019 / Published: 10 April 2019
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Abstract
The surface plasmon resonance (SPR) technique is a powerful method to detect chemical molecules. Fluorescent spectroscopy is a subject of great interest in the field of material science and biology. Recently, some optical sensors, based on plasmonic properties of nanomaterial, were introduced to [...] Read more.
The surface plasmon resonance (SPR) technique is a powerful method to detect chemical molecules. Fluorescent spectroscopy is a subject of great interest in the field of material science and biology. Recently, some optical sensors, based on plasmonic properties of nanomaterial, were introduced to enhance the investigation of the interaction of molecular while detecting the low concentration of molecular. The surface plasmon-coupled emission (SPCE) technique is a merit and accurate method to evaluate the interaction of nanomaterials and molecular. SPCE is based on fluorescence properties of interest molecule, and the surface plasmon enhances the fluorescence signal. According to SPR theory, the condition of excitation of fluorophore could be used in obtaining the SPCE signal. SPCE can be used to detect toxic chemicals and investigate the human molecular. In this review, the theory, experimental setup, condition of SPCE, and role of metal nanoparticles in SPCE were reviewed. In the end, the application of SPCE was presented for detection and monitoring the chemical material, heavy metal, and biologic molecules. Full article
(This article belongs to the Special Issue Plasmonic Nanosensors)
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Open AccessArticle
Transient Numerical Simulation of Regenerative Systems with Waste Gas Recirculation Strategies in Glass Production Plant
Appl. Sci. 2019, 9(7), 1496; https://doi.org/10.3390/app9071496
Received: 22 February 2019 / Revised: 26 March 2019 / Accepted: 27 March 2019 / Published: 10 April 2019
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Abstract
The glass production industry has one of the highest energy consumption rates and environmental emission impacts with respect to the existing industrial sectors. Glass furnaces nowadays are conceived with regenerative systems to take advantage of the residual heat from the combustion exhausts in [...] Read more.
The glass production industry has one of the highest energy consumption rates and environmental emission impacts with respect to the existing industrial sectors. Glass furnaces nowadays are conceived with regenerative systems to take advantage of the residual heat from the combustion exhausts in order to increase the thermal efficiency of the system. The exhaust gases are also used in innovative systems to reduce the NOx emissions in specifically designed gas recirculation systems tailored to the glass furnace. In this paper, a numerical model for the simulation of the regenerative chambers in both steady and unsteady conditions is presented. The option of gas recirculation is also included. Special attention has been focused on the radiative heat transfer from the recirculated gases using a gas emissivity model previously developed by the authors. Full article
(This article belongs to the Section Mechanical Engineering)
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Open AccessArticle
An Accuracy-Efficiency-Power Consumption Hybrid Optimization Method for CNC Milling Process
Appl. Sci. 2019, 9(7), 1495; https://doi.org/10.3390/app9071495
Received: 3 March 2019 / Revised: 6 April 2019 / Accepted: 8 April 2019 / Published: 10 April 2019
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Abstract
This study proposes a hybrid optimization method which can help users to find optimal cutting parameters which will provide better efficiency and lower power consumption for a milling process. Empirical models including performance-power consumption characteristic curves of servo motors were built, and an [...] Read more.
This study proposes a hybrid optimization method which can help users to find optimal cutting parameters which will provide better efficiency and lower power consumption for a milling process. Empirical models including performance-power consumption characteristic curves of servo motors were built, and an optimization algorithm adopting the empirical models with procedure guiding function was developed. The empirical models were built based on the measurements from planned machining experiments with different combination of machining parameters including spindle speed, feedrate, and chip load, etc. After integrating the models and algorithm, an optimization system with human machine interface, which has procedure guiding function, was developed. The system can recommend optimal machining parameters for a milling process for shorter machining time and lower electricity costs based on the original machining parameters. Finally, cutting experiments were conducted to verify the proposed system, and the results showed that the proposed method can effectively enhance efficiency by 42.06% and save 34.74% in machining costs through reducing machining time and electrical power consumption. Full article
(This article belongs to the Special Issue Precision Dimensional Measurements)
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Open AccessArticle
Fractal Dimension Differentiation between Benign and Malignant Thyroid Nodules from Ultrasonography
Appl. Sci. 2019, 9(7), 1494; https://doi.org/10.3390/app9071494
Received: 1 February 2019 / Revised: 13 March 2019 / Accepted: 28 March 2019 / Published: 10 April 2019
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Abstract
Recently, there is increasing interest in identifying benign and malignant nodules by using ultrasound diagnostic technology, which should be helpful to release patients with benign thyroid nodules from suffering unnecessary needle biopsy. In this work, fractal analysis was investigated for the capability of [...] Read more.
Recently, there is increasing interest in identifying benign and malignant nodules by using ultrasound diagnostic technology, which should be helpful to release patients with benign thyroid nodules from suffering unnecessary needle biopsy. In this work, fractal analysis was investigated for the capability of differentiating benign from malignant thyroid nodules during ultrasonography. The B-mode images for 57 patients with suspicious thyroid nodules were captured, followed by ultrasound-guided needle aspiration. The region of interests (ROIs) were subsequently selected from ultrasound images. Then, fractal analysis was performed to extract fractal texture features, and derive the fractal dimension of ROI. The results showed that a significant difference was observed between benign and malignant thyroid nodules (p < 0.05), by comparing this parameter based on independent nonparametric Mann‒Whitney U test. It suggested that fractal dimension is a helpful feature for distinguishing thyroid nodules. In addition, fractal analysis of the B-mode image can provide a reliable reference for tissue typing in ultrasound diagnosis. Full article
(This article belongs to the Section Acoustics and Vibrations)
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Open AccessArticle
Precise Identification of Coal Thickness by Channel Wave Based on a Hybrid Algorithm
Appl. Sci. 2019, 9(7), 1493; https://doi.org/10.3390/app9071493
Received: 17 March 2019 / Revised: 30 March 2019 / Accepted: 8 April 2019 / Published: 10 April 2019
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Abstract
Precise prediction of coal thickness is of the utmost importance in realizing intelligent and unmanned mining. As the channel wave is characterized by an easily recognizable waveform, a long propagation distance, and strong energy, it is widely used for coal thickness inversion. However, [...] Read more.
Precise prediction of coal thickness is of the utmost importance in realizing intelligent and unmanned mining. As the channel wave is characterized by an easily recognizable waveform, a long propagation distance, and strong energy, it is widely used for coal thickness inversion. However, most traditional inversion methods are local in nature, and the inversion result is probably not optimal in the global scope. This paper introduces the GA-SIRT hybrid approach, which combines Genetic Algorithms (GA) and Simultaneous Iterative Reconstructive Techniques (SIRT) in order to deal with the above problem and to improve the accuracy of coal thickness inversion. The proposed model takes full advantage of the strong global search capability of GA and of the fast local convergence rate of the SIRT. Moreover, it inhibits the poor local search ability and the local optimal value effect of the GA and the SIRT respectively. The application of the GA-SIRT in the Guoerzhuang coal mine has significantly enhanced its accuracy, stability, and overall computational efficiency. Hence, the introduced novel hybrid model can precisely resolve and identify the coal thickness according to the channel wave. It can also be extended to other geophysical tomographic inversion problems towards the reduction of potential local optimal solutions. Full article
(This article belongs to the Section Environmental and Sustainable Science and Technology)
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Open AccessArticle
Mechanical Behaviour of TRC Composites: Experimental and Analytical Approaches
Appl. Sci. 2019, 9(7), 1492; https://doi.org/10.3390/app9071492
Received: 15 March 2019 / Revised: 2 April 2019 / Accepted: 3 April 2019 / Published: 10 April 2019
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Abstract
Textile reinforced concrete (TRC) is a promising high-performance material that has been employed with success in new constructions, as well as a strengthening layer of existing structural components. In this work, we document the optimisation procedure of textile-based composites for new construction and [...] Read more.
Textile reinforced concrete (TRC) is a promising high-performance material that has been employed with success in new constructions, as well as a strengthening layer of existing structural components. In this work, we document the optimisation procedure of textile-based composites for new construction and for the seismic retrofitting of under-reinforced concrete elements and masonry buildings. The study, aimed at maximising the material performances avoiding waste of economic resources, was addressed by means of a series of uniaxial tensile tests conducted on a wide set of alkali-resistant (AR) glass fabrics and TRCs. The samples differed in terms of cement-based matrices, embedded textiles and addition of dispersed microfibers. The results highlight the effects of fabric characteristics and introduction of short fibres on the mechanical behaviour, proposing novel comparison parameters based upon the load bearing capacity and the deformation response of the composites. The application of simplified analytical models borrowed from the literature finally revealed the limitations of the available predictive approaches, suggesting future lines of investigation. Full article
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Open AccessArticle
Performance of Warm-Mixed Flame Retardant Modified Asphalt Binder
Appl. Sci. 2019, 9(7), 1491; https://doi.org/10.3390/app9071491
Received: 18 March 2019 / Revised: 2 April 2019 / Accepted: 8 April 2019 / Published: 10 April 2019
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Abstract
In order to analyze the effect of flame retardant and warm mix asphalt (WMA) additives-Sasobit on the flame-retardant performance and pavement performance of asphalt binder, the limiting oxygen index test, conventional performance test, and Superpave evaluation index tests were performed on asphalt binders [...] Read more.
In order to analyze the effect of flame retardant and warm mix asphalt (WMA) additives-Sasobit on the flame-retardant performance and pavement performance of asphalt binder, the limiting oxygen index test, conventional performance test, and Superpave evaluation index tests were performed on asphalt binders in the study. The test results show that flame retardant can effectively improve the flame resistance of asphalt binder, while Sasobit has a certain combustion-supporting effect. Therefore, when warm-mixed flame-retardant technology is applied, the concentration of Sasobit should be controlled appropriately. These two modifiers can significantly enhance the high-temperature performance of asphalt binder, but both of them have a slight negative influence on the low-temperature cracking resistance. Sasobit can substantially reduce the high-temperature viscosity of asphalt binder, which helps to improve the construction workability of asphalt binder, while the flame retardant adversely affects the viscosity reduction effect of Sasobit to a certain extent, but the overall impact is not large. Full article
(This article belongs to the Section Materials)
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Open AccessArticle
Effect of Different Acoustic Parameters on NOx Emissions of Partially Premixed Flame
Appl. Sci. 2019, 9(7), 1490; https://doi.org/10.3390/app9071490
Received: 9 February 2019 / Revised: 30 March 2019 / Accepted: 1 April 2019 / Published: 10 April 2019
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Abstract
The effects of acoustic frequency (f)/0–400 Hz and amplitude (A)/0–1400 Pa on nitrogen oxides (NOx) emissions of a partially premixed flame were investigated experimentally. The mechanism of NOx emissions was analyzed by the evolution of the vortex, which was [...] Read more.
The effects of acoustic frequency (f)/0–400 Hz and amplitude (A)/0–1400 Pa on nitrogen oxides (NOx) emissions of a partially premixed flame were investigated experimentally. The mechanism of NOx emissions was analyzed by the evolution of the vortex, which was shown by particle image velocimetry (PIV). From the relationship of NOx emission index (EINOx) and acoustic parameters, it was concluded that a critical frequency (fc) from 170 Hz to 190 Hz appeared. When the frequency was less than fc, EINOx decreased linearly with an increase in amplitude. The flame length became shorter, which led to a decrease in the global residence time, and hence, a reduction in reaction time for NOx. However, a direct proportional relationship between EINOx and amplitude was not found when the frequency was larger than fc. Based on PIV particle scattering images, with an increase of the acoustic frequency, the effects of the acoustic field on the flame base became less significant, but the flame length and reaction space of NOx were gradually increased. Full article
(This article belongs to the Special Issue Progress in Combustion Diagnostics, Science and Technology)
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Open AccessArticle
Shear Properties of Asphalt Mixtures under Triaxial Compression
Appl. Sci. 2019, 9(7), 1489; https://doi.org/10.3390/app9071489
Received: 27 March 2019 / Accepted: 2 April 2019 / Published: 10 April 2019
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Abstract
In order to study the influences of confining pressure and temperature on the shear properties of asphalt mixtures, triaxial tests were conducted at 40 °C, 50 °C, and 60 °C, with the confining pressure ranges from 0 to 1 MPa for the widely [...] Read more.
In order to study the influences of confining pressure and temperature on the shear properties of asphalt mixtures, triaxial tests were conducted at 40 °C, 50 °C, and 60 °C, with the confining pressure ranges from 0 to 1 MPa for the widely used continuous-graded AC (Asphalt Concrete)-13, open-graded OGFC (Open-Graded Friction Course)-13, and gap-graded SMA (Stone Mastic Asphalt)-13 asphalt mixtures in China. A nonlinear regression/prediction model of triaxial strength for asphalt mixtures was proposed. The results show that confining pressure and temperature had a significant effect on the shear resistance of asphalt mixtures. With increasing temperature, the shear strength of the asphalt mixture gradually decreased due to the decreasing of cohesion strength; the shear strength of the asphalt mixture increased with the increase of confining pressure. Meanwhile, the cohesion strength increased and the friction angle decreased gradually with the increase of confining pressure. When the confining pressure was close to 0.6 MPa, the Mohr–Coulomb failure envelope bended down, so the linear Mohr–Coulomb criterion is not suitable to describe the failure behavior of asphalt mixtures. Therefore, a power function failure envelope was put forward to characterize the nonlinear shear properties of asphalt mixtures. The nonlinear evolutional laws of shear parameters, which includes cohesion strength and friction angle, were also proposed for asphalt pavement material and structure design. Among these asphalt mixtures, the gap-graded SMA-13 asphalt mixture exhibited better performance on the resistance to shear failure, and it was recommended as the upper layer material to improve the shear performance of asphalt pavement. Full article
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Open AccessArticle
A Novel Frequency Domain Visible Light Communication (VLC) Three-Dimensional Trilateration System for Localization in Underground Mining
Appl. Sci. 2019, 9(7), 1488; https://doi.org/10.3390/app9071488
Received: 1 March 2019 / Revised: 26 March 2019 / Accepted: 30 March 2019 / Published: 10 April 2019
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Abstract
A new visible light communication (VLC) system is proposed for localization in underground mining. Existent systems, such as global positioning system (GPS) and systems based on mobile communication, are generally not useful in underground mining. The proposed system is based on a three-dimensional [...] Read more.
A new visible light communication (VLC) system is proposed for localization in underground mining. Existent systems, such as global positioning system (GPS) and systems based on mobile communication, are generally not useful in underground mining. The proposed system is based on a three-dimensional trilateration VLC localization scheme. This articles offers an evaluation of the proposed system in different evaluation scenarios in terms of the average localization error. The proposed algorithm localizes the source with an average localization estimation error of less than (16.4 cm), based on the source location. The average error is (3.5 cm) for subjects that are very close to the light-emitting-diode (LEDs).The obtained results show the superiority of the proposed method in comparison with traditional short range radio frequency technologies such as RFID, Wi-Fi and Zigbee, making it a feasible system for localizing objects in underground mining. Full article
(This article belongs to the Special Issue Light Communication: Latest Advances and Prospects)
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Open AccessArticle
An Ultrashort-Term Net Load Forecasting Model Based on Phase Space Reconstruction and Deep Neural Network
Appl. Sci. 2019, 9(7), 1487; https://doi.org/10.3390/app9071487
Received: 28 February 2019 / Revised: 24 March 2019 / Accepted: 2 April 2019 / Published: 9 April 2019
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Abstract
Recently, a large number of distributed photovoltaic (PV) power generations have been connected to the power grid, which resulted in an increased fluctuation of the net load. Therefore, load forecasting has become more difficult. Considering the characteristics of the net load, an ultrashort-term [...] Read more.
Recently, a large number of distributed photovoltaic (PV) power generations have been connected to the power grid, which resulted in an increased fluctuation of the net load. Therefore, load forecasting has become more difficult. Considering the characteristics of the net load, an ultrashort-term forecasting model based on phase space reconstruction and deep neural network (DNN) is proposed, which can be divided into two steps. First, the phase space reconstruction of the net load time series data is performed using the C-C method. Second, the reconstructed data is fitted by the DNN to obtain the predicted value of the net load. The performance of this model is verified using real data. The accuracy is high in forecasting the net load under high PV penetration rate and different weather conditions. Full article
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Open AccessArticle
Computational Study of Wet Steam Flow to Optimize Steam Ejector Efficiency for Potential Fire Suppression Application
Appl. Sci. 2019, 9(7), 1486; https://doi.org/10.3390/app9071486
Received: 2 March 2019 / Revised: 3 April 2019 / Accepted: 4 April 2019 / Published: 9 April 2019
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Abstract
The steam ejector is a core component of an ejector-based refrigeration system. Additionally, steam ejectors can also be potentially applied for a fire suppression system by using pressurized steam droplets to rapidly quench and extinguish the fire. The use of steam will significantly [...] Read more.
The steam ejector is a core component of an ejector-based refrigeration system. Additionally, steam ejectors can also be potentially applied for a fire suppression system by using pressurized steam droplets to rapidly quench and extinguish the fire. The use of steam will significantly reduce the amount of water consumption and pipe flow rate compared to conventional sprinklers. However, the efficiency of the steam ejector nozzle is one of major factors that can influence the extinguishing mechanisms and the performance of pressurized steam for fire suppression. In this article, to formulate an assessment tool for studying the ideal entrainment ratio and initial flow wetness, a wet steam model has been proposed to enhance our understanding of the condensation and evaporation effects of water droplets from a numerical perspective. The entire steam-ejector system including the nozzle, mixing chamber, throat and diffuser were modeled to study the profiles in axial pressure and temperature across the system, and were compared with self-measured experimental data. In addition, the flow and heat transfer interactions between the fluid mixture and nucleating water droplets were numerically examined by comparing initial conditions with different liquid fractions, as opposed to the ideal gas assumption. With the application of the proposed wet-steam model, the numerical model showed vast improvement in the axial pressure distribution over the ideal gas model. Through numerical conditions, it was found that reducing the wetness of the secondary inlet flow will potentially optimize the system performance with a significant increase of the entrainment ratio from 0.38 to 0.47 (i.e., improvement of around 23%). Full article
(This article belongs to the Special Issue Progress in Combustion Diagnostics, Science and Technology)
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