Next Issue
Previous Issue

Table of Contents

Appl. Sci., Volume 6, Issue 4 (April 2016)

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
View options order results:
result details:
Displaying articles 1-29
Export citation of selected articles as:
Open AccessArticle
Dynamics of a Stochastic Intraguild Predation Model
Appl. Sci. 2016, 6(4), 118; https://doi.org/10.3390/app6040118
Received: 25 December 2015 / Revised: 13 April 2016 / Accepted: 14 April 2016 / Published: 22 April 2016
Cited by 2 | Viewed by 1207 | PDF Full-text (2715 KB) | HTML Full-text | XML Full-text
Abstract
Intraguild predation (IGP) is a widespread ecological phenomenon which occurs when one predator species attacks another predator species with which it competes for a shared prey species. The objective of this paper is to study the dynamical properties of a stochastic intraguild predation [...] Read more.
Intraguild predation (IGP) is a widespread ecological phenomenon which occurs when one predator species attacks another predator species with which it competes for a shared prey species. The objective of this paper is to study the dynamical properties of a stochastic intraguild predation model. We analyze stochastic persistence and extinction of the stochastic IGP model containing five cases and establish the sufficient criteria for global asymptotic stability of the positive solutions. This study shows that it is possible for the coexistence of three species under the influence of environmental noise, and that the noise may have a positive effect for IGP species. A stationary distribution of the stochastic IGP model is established and it has the ergodic property, suggesting that the time average of population size with the development of time is equal to the stationary distribution in space. Finally, we show that our results may be extended to two well-known biological systems: food chains and exploitative competition. Full article
(This article belongs to the Special Issue Dynamical Models of Biology and Medicine)
Figures

Figure 1

Open AccessArticle
Influence of the Quality of Consumer Headphones in the Perception of Spatial Audio
Appl. Sci. 2016, 6(4), 117; https://doi.org/10.3390/app6040117
Received: 29 February 2016 / Revised: 4 April 2016 / Accepted: 12 April 2016 / Published: 22 April 2016
Cited by 2 | Viewed by 2150 | PDF Full-text (1309 KB) | HTML Full-text | XML Full-text
Abstract
High quality headphones can generate a realistic sound immersion reproducing binaural recordings. However, most people commonly use consumer headphones of inferior quality, as the ones provided with smartphones or music players. Factors, such as weak frequency response, distortion and the sensitivity disparity between [...] Read more.
High quality headphones can generate a realistic sound immersion reproducing binaural recordings. However, most people commonly use consumer headphones of inferior quality, as the ones provided with smartphones or music players. Factors, such as weak frequency response, distortion and the sensitivity disparity between the left and right transducers could be some of the degrading factors. In this work, we are studying how these factors affect spatial perception. To this purpose, a series or perceptual tests have been carried out with a virtual headphone listening test methodology. The first experiment focuses on the analysis of how the disparity of sensitivity between the two transducers affects the final result. The second test studies the influence of the frequency response relating quality and spatial impression. The third test analyzes the effects of distortion using a Volterra kernels scheme for the simulation of the distortion using convolutions. Finally, the fourth tries to relate the quality of the frequency response with the accuracy on azimuth localization. The conclusions of the experiments are: the disparity between both transducers can affect the localization of the source; the perception of quality and spatial impression has a high correlation; the distortion produced by the range of headphones tested at a fixed level does not affect the perception of binaural sound; and that some frequency bands have an important role in the front-back confusions. Full article
(This article belongs to the Special Issue Audio Signal Processing) Printed Edition available
Figures

Figure 1

Open AccessArticle
Semantically Controlled Adaptive Equalisation in Reduced Dimensionality Parameter Space
Appl. Sci. 2016, 6(4), 116; https://doi.org/10.3390/app6040116
Received: 24 February 2016 / Revised: 4 April 2016 / Accepted: 5 April 2016 / Published: 20 April 2016
Cited by 4 | Viewed by 1835 | PDF Full-text (1413 KB) | HTML Full-text | XML Full-text
Abstract
Equalisation is one of the most commonly-used tools in sound production, allowing users to control the gains of different frequency components in an audio signal. In this paper we present a model for mapping a set of equalisation parameters to a reduced dimensionality [...] Read more.
Equalisation is one of the most commonly-used tools in sound production, allowing users to control the gains of different frequency components in an audio signal. In this paper we present a model for mapping a set of equalisation parameters to a reduced dimensionality space. The purpose of this approach is to allow a user to interact with the system in an intuitive way through both the reduction of the number of parameters and the elimination of technical knowledge required to creatively equalise the input audio. The proposed model represents 13 equaliser parameters on a two-dimensional plane, which is trained with data extracted from a semantic equalisation plug-in, using the timbral adjectives warm and bright. We also include a parameter weighting stage in order to scale the input parameters to spectral features of the audio signal, making the system adaptive. To maximise the efficacy of the model, we evaluate a variety of dimensionality reduction and regression techniques, assessing the performance of both parameter reconstruction and structural preservation in low-dimensional space. After selecting an appropriate model based on the evaluation criteria, we conclude by subjectively evaluating the system using listening tests. Full article
(This article belongs to the Special Issue Audio Signal Processing) Printed Edition available
Figures

Figure 1

Open AccessArticle
Biaxial-Type Concentrated Solar Tracking System with a Fresnel Lens for Solar-Thermal Applications
Appl. Sci. 2016, 6(4), 115; https://doi.org/10.3390/app6040115
Received: 28 December 2015 / Revised: 8 April 2016 / Accepted: 11 April 2016 / Published: 20 April 2016
Cited by 2 | Viewed by 2229 | PDF Full-text (1825 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, an electromechanical, biaxial-type concentrated solar tracking system was designed for solar-thermal applications. In our tracking system, the sunlight was concentrated by the microstructure of Fresnel lens to the heating head of the Stirling engine and two solar cells were installed [...] Read more.
In this paper, an electromechanical, biaxial-type concentrated solar tracking system was designed for solar-thermal applications. In our tracking system, the sunlight was concentrated by the microstructure of Fresnel lens to the heating head of the Stirling engine and two solar cells were installed to provide the power for tracking system operation. In order to obtain the maximum sun power, the tracking system traces the sun with the altitude-azimuth biaxial tracing method and accurately maintains the sun’s radiation perpendicular to the plane of the heating head. The results indicated that the position of heating head is an important factor for power collection. If the sunlight can be concentrated to completely cover the heating head with small heat loss, we can obtain the maximum temperature of the heating head of the Stirling engine. Therefore, the temperature of heating head can be higher than 1000 °C in our experiment on a sunny day. Moreover, the results also revealed that the temperature decrease of the heating head is less than the power decrease of solar irradiation because of the latent heat of copper and the small heat loss from the heating head. Full article
Figures

Figure 1

Open AccessArticle
Experimental and Numerical Studies of Controlling Thermal Cracks in Mass Concrete Foundation by Circulating Water
Appl. Sci. 2016, 6(4), 110; https://doi.org/10.3390/app6040110
Received: 26 January 2016 / Revised: 11 April 2016 / Accepted: 13 April 2016 / Published: 20 April 2016
Cited by 4 | Viewed by 2051 | PDF Full-text (6402 KB) | HTML Full-text | XML Full-text
Abstract
This paper summarizes an engineering experience of solving the problem of thermal cracking in mass concrete by using a large project, Zhongguancun No.1 (Beijing, China), as an example. A new method is presented for controlling temperature cracks in the mass concrete of a [...] Read more.
This paper summarizes an engineering experience of solving the problem of thermal cracking in mass concrete by using a large project, Zhongguancun No.1 (Beijing, China), as an example. A new method is presented for controlling temperature cracks in the mass concrete of a foundation. The method involves controlled cycles of water circulating between the surface of mass concrete foundation and the atmospheric environment. The temperature gradient between the surface and the core of the mass concrete is controlled at a relatively stable state. Water collected from the well-points used for dewatering and from rainfall is used as the source for circulating water. Mass concrete of a foundation slab is experimentally investigated through field temperature monitoring. Numerical analyses are performed by developing a finite element model of the foundation with and without water circulation. The calculation parameters are proposed based on the experiment, and finite element analysis software MIDAS/CIVIL is used to calculate the 3D temperature field of the mass concrete during the entire process of heat of hydration. The numerical results are in good agreement with the measured results. The proposed method provides an alternative practical basis for preventing thermal cracks in mass concrete. Full article
Figures

Figure 1

Open AccessArticle
Quantitative Assessment of Variational Surface Reconstruction from Sparse Point Clouds in Freehand 3D Ultrasound Imaging during Image-Guided Tumor Ablation
Appl. Sci. 2016, 6(4), 114; https://doi.org/10.3390/app6040114
Received: 13 December 2015 / Revised: 9 April 2016 / Accepted: 12 April 2016 / Published: 19 April 2016
Cited by 1 | Viewed by 2037 | PDF Full-text (5671 KB) | HTML Full-text | XML Full-text
Abstract
Surface reconstruction for freehand 3D ultrasound is used to provide 3D visualization of a VOI (volume of interest) during image-guided tumor ablation surgery. This is a challenge because the recorded 2D B-scans are not only sparse but also non-parallel. To solve this issue, [...] Read more.
Surface reconstruction for freehand 3D ultrasound is used to provide 3D visualization of a VOI (volume of interest) during image-guided tumor ablation surgery. This is a challenge because the recorded 2D B-scans are not only sparse but also non-parallel. To solve this issue, we established a framework to reconstruct the surface of freehand 3D ultrasound imaging in 2011. The key technique for surface reconstruction in that framework is based on variational interpolation presented by Greg Turk for shape transformation and is named Variational Surface Reconstruction (VSR). The main goal of this paper is to evaluate the quality of surface reconstructions, especially when the input data are extremely sparse point clouds from freehand 3D ultrasound imaging, using four methods: Ball Pivoting, Power Crust, Poisson, and VSR. Four experiments are conducted, and quantitative metrics, such as the Hausdorff distance, are introduced for quantitative assessment. The experiment results show that the performance of the proposed VSR method is the best of the four methods at reconstructing surface from sparse data. The VSR method can produce a close approximation to the original surface from as few as two contours, whereas the other three methods fail to do so. The experiment results also illustrate that the reproducibility of the VSR method is the best of the four methods. Full article
Figures

Figure 1

Open AccessArticle
A Novel Method for Estimation of Femoral Neck Bone Mineral Density Using Forearm Images from Peripheral Cone Beam Computed Tomography
Appl. Sci. 2016, 6(4), 113; https://doi.org/10.3390/app6040113
Received: 29 February 2016 / Revised: 6 April 2016 / Accepted: 11 April 2016 / Published: 19 April 2016
Cited by 2 | Viewed by 1477 | PDF Full-text (2365 KB) | HTML Full-text | XML Full-text
Abstract
The main goal of osteoporosis treatment is prevention of osteoporosis-induced bone fracture. Dual-energy X-ray absorptiometry (DXA) and quantitative computed tomographic imaging (QCT) are widely used for assessment of bone mineral density (BMD). However, they have limitations in patients with special conditions. This study [...] Read more.
The main goal of osteoporosis treatment is prevention of osteoporosis-induced bone fracture. Dual-energy X-ray absorptiometry (DXA) and quantitative computed tomographic imaging (QCT) are widely used for assessment of bone mineral density (BMD). However, they have limitations in patients with special conditions. This study evaluated a method for diagnosis of osteoporosis using peripheral cone beam computed tomography (CBCT) to estimate BMD. We investigated the correlation between the ratio of cortical and total bone areas of the forearm and femoral neck BMD. Based on the correlation, we established a linear transformation between the ratio and femoral neck BMD. We obtained forearm images using CBCT and femoral neck BMDs using dual-energy X-ray absorptiometry (DXA) for 23 subjects. We first calculated the ratio of the cortical to the total bone area in the forearm from the CBCT images, and investigated the relationship with the femoral neck BMDs obtained from DXA. Based on this relationship, we further investigated the optimal forearm region to provide the highest correlation coefficient. We used the optimized forearm region to establish a linear transformation of the form to estimate femoral neck BMD from the calculated ratio. We observed the correlation factor of r = 0.857 (root mean square error = 0.056435 g/cm2; mean absolute percentage error = 4.5105%) between femoral neck BMD and the ratio of the cortical and total bone areas. The strongest correlation was observed for the average ratios of the mid-shaft regions of the ulna and radius. Our results suggest that femoral neck BMD can be estimated from forearm CBCT images and may be useful for screening osteoporosis, with patients in a convenient sitting position. We believe that peripheral CBCT image-based BMD estimation may have significant preventative value for early osteoporosis treatment and management. Full article
Figures

Figure 1

Open AccessArticle
Experimental Evaluation of a Paraffin as Phase Change Material for Thermal Energy Storage in Laboratory Equipment and in a Shell-and-Tube Heat Exchanger
Appl. Sci. 2016, 6(4), 112; https://doi.org/10.3390/app6040112
Received: 2 March 2016 / Revised: 6 April 2016 / Accepted: 8 April 2016 / Published: 18 April 2016
Cited by 13 | Viewed by 2785 | PDF Full-text (2518 KB) | HTML Full-text | XML Full-text
Abstract
The thermal behavior of a commercial paraffin with a melting temperature of 58 °C is analyzed as a phase change material (PCM) candidate for industrial waste heat recovery and domestic hot water applications. A full and complete characterization of this PCM is performed [...] Read more.
The thermal behavior of a commercial paraffin with a melting temperature of 58 °C is analyzed as a phase change material (PCM) candidate for industrial waste heat recovery and domestic hot water applications. A full and complete characterization of this PCM is performed based on two different approaches: a laboratory characterization (mass range of milligrams) and an analysis in a pilot plant (mass range of kilograms). In the laboratory characterization, its thermal and cycling stability, its health hazard as well as its phase change thermal range, enthalpy and specific heat are analyzed using a differential scanning calorimeter, thermogravimetric analysis, thermocycling and infrared spectroscopy. Laboratory analyses showed its suitability up to 80 °C and for 1200 cycles. In the pilot plant analysis, its thermal behavior was analyzed in a shell-and-tube heat exchanger under different heat transfer fluid mass flow rates in terms of temperature, power and energy rates. Results from the pilot plant analysis allowed understanding the different methods of heat transfer in real charging and discharging processes as well as the influence of the geometry of the tank on the energy transferred and required time for charging and discharging processes. Full article
(This article belongs to the Special Issue Phase Change Materials (PCM))
Figures

Figure 1

Open AccessArticle
Characterization and Clinical Trial of an Innovative High-Speed Lancing Device
Appl. Sci. 2016, 6(4), 111; https://doi.org/10.3390/app6040111
Received: 22 February 2016 / Revised: 22 March 2016 / Accepted: 6 April 2016 / Published: 18 April 2016
Cited by 1 | Viewed by 1603 | PDF Full-text (1451 KB) | HTML Full-text | XML Full-text
Abstract
An innovative high-speed lancing device has a lancet that moves so fast that it is not affected at all by the vibration of its spring, and does not pierce the skin repeatedly, greatly reducing the pain that is caused to diabetes mellitus (DM) [...] Read more.
An innovative high-speed lancing device has a lancet that moves so fast that it is not affected at all by the vibration of its spring, and does not pierce the skin repeatedly, greatly reducing the pain that is caused to diabetes mellitus (DM) patients during blood sampling. As revealed by experimental measurements of the acceleration of a lancet using an accelerometer, the lancet pierces the skin only once. The maximum acceleration and the instant piercing velocity of the lancet are 9.4 times and 1.78 times those of a conventional lancing device, respectively. Meanwhile, the period for which the lancet remains in the skin is 0.014 s shorter than that of the conventional lancing device. A clinical trial that involved 100 participants yielded statistical results concerning the numeric rating of pain scale (NRS) of pain intensity, which is internationally recognized as the pain with the highest validity, that showed that the NRS of participants who used the innovative high-speed lancing device was 2.65 less than that of those who used the conventional lancing device, and the duration of the pain after blood sampling was 76.1 min shorter. Full article
(This article belongs to the Special Issue Selected Papers from the 2015 International Conference on Inventions)
Figures

Figure 1

Open AccessReview
A Review of Double-Walled and Triple-Walled Carbon Nanotube Synthesis and Applications
Appl. Sci. 2016, 6(4), 109; https://doi.org/10.3390/app6040109
Received: 31 December 2015 / Revised: 7 March 2016 / Accepted: 9 March 2016 / Published: 16 April 2016
Cited by 15 | Viewed by 2739 | PDF Full-text (1913 KB) | HTML Full-text | XML Full-text
Abstract
Double- and triple-walled carbon nanotubes (DWNTs and TWNTs) consist of coaxially-nested two and three single-walled carbon nanotubes (SWNTs). They act as the geometrical bridge between SWNTs and multi-walled carbon nanotubes (MWNTs), providing an ideal model for studying the coupling interactions between different shells [...] Read more.
Double- and triple-walled carbon nanotubes (DWNTs and TWNTs) consist of coaxially-nested two and three single-walled carbon nanotubes (SWNTs). They act as the geometrical bridge between SWNTs and multi-walled carbon nanotubes (MWNTs), providing an ideal model for studying the coupling interactions between different shells in MWNTs. Within this context, this article comprehensively reviews various synthetic routes of DWNTs’ and TWNTs’ production, such as arc discharge, catalytic chemical vapor deposition and thermal annealing of pea pods (i.e., SWNTs encapsulating fullerenes). Their structural features, as well as promising applications and future perspectives are also discussed. Full article
Figures

Figure 1

Open AccessArticle
WIPP: Wi-Fi Compass for Indoor Passive Positioning with Decimeter Accuracy
Appl. Sci. 2016, 6(4), 108; https://doi.org/10.3390/app6040108
Received: 3 March 2016 / Revised: 29 March 2016 / Accepted: 30 March 2016 / Published: 13 April 2016
Cited by 3 | Viewed by 2135 | PDF Full-text (2624 KB) | HTML Full-text | XML Full-text
Abstract
In recent decades, the proliferation of smart phones, tablets, and wireless networks has fostered a growing interest in indoor passive positioning. The Wi-Fi-based passive positioning systems can provide Location-Based Services (LBSs) to the third party such as market and security departments. Most of [...] Read more.
In recent decades, the proliferation of smart phones, tablets, and wireless networks has fostered a growing interest in indoor passive positioning. The Wi-Fi-based passive positioning systems can provide Location-Based Services (LBSs) to the third party such as market and security departments. Most of the existing systems are based on the Receive Signal Strength Indication (RSSI) information, which are generally time-consuming and susceptible to environmental change. To overcome this problem, we propose the Wi-Fi compass for indoor passive positioning system (WIPP), an Angle of Arrival (AOA) based passive positioning system using the existing commodity Wi-Fi network. In this paper, we first propose a new algorithm for the joint estimation of AOA and Time of Arrival (TOA) measurements based on the fine-grained Channel State Information (CSI), which is collected by an off-the-shelf Wi-Fi device equipped with only three antennas. Second, we use the affinity propagation clustering algorithm to identify the direct signal path from the target to each Wi-Fi Access Point (AP). Finally, we deploy the WIPP in an actual indoor environment to conduct the performance comparison with the well-known radio-frequency (RF) based system for locating and tracking users inside buildings (RADAR), as well as the conventional passive positioning system using the AOA solely. The experimental results show that the WIPP is able to achieve the median positioning error 0.7 m, which is much lower than the ones by the RADAR system and the conventional system using the AOA solely. Full article
Figures

Figure 1

Open AccessArticle
Methods of In-Process On-Machine Auto-Inspection of Dimensional Error and Auto-Compensation of Tool Wear for Precision Turning
Appl. Sci. 2016, 6(4), 107; https://doi.org/10.3390/app6040107
Received: 1 February 2016 / Revised: 20 March 2016 / Accepted: 21 March 2016 / Published: 12 April 2016
Cited by 5 | Viewed by 2104 | PDF Full-text (11188 KB) | HTML Full-text | XML Full-text
Abstract
The purpose of this study is mainly to develop an information and communication technology (ICT)-based intelligent dimension inspection and tool wear compensation method for precision tuning. With the use of vibration signal processing/characteristics analysis technology combined with ICT, statistical analysis, and diagnosis algorithms, [...] Read more.
The purpose of this study is mainly to develop an information and communication technology (ICT)-based intelligent dimension inspection and tool wear compensation method for precision tuning. With the use of vibration signal processing/characteristics analysis technology combined with ICT, statistical analysis, and diagnosis algorithms, the method can be used to proceed with an on-line dimension inspection and on-machine tool wear auto-compensation for the turning process. Meanwhile, the method can also monitor critical tool life to identify the appropriate time for cutter replacement to reduce machining costs and improve the production efficiency of the turning process. Compared to the traditional ways, the method offers the advantages of requiring less manpower, and having better production efficiency, high tool life, fewer scrap parts, and low costs for inspection instruments. Algorithms and diagnosis threshold values for the detection, cutter wear compensation, and cutter life monitoring were developed. In addition, a bilateral communication module utilizing FANUC Open CNC (computer numerical control) Application Programming Interface (API) Spec was developed for the on-line extraction of instant NC (numerical control) codes for monitoring and transmit commands to CNC controllers for cutter wear compensation. With use of local area networks (LAN) to deliver the detection and correction information, the proposed method was able to remotely control the on-machine monitoring process and upload the machining and inspection data to a remote central platform for further production optimization. The verification experiments were conducted on a turning production line. The results showed that the system provided 93% correction for size inspection and 100% correction for cutter wear compensation. Full article
Figures

Figure 1

Open AccessArticle
Thermal Performance Evaluation of Fatty Acid Ester and Paraffin Based Mixed SSPCMs Using Exfoliated Graphite Nanoplatelets (xGnP)
Appl. Sci. 2016, 6(4), 106; https://doi.org/10.3390/app6040106
Received: 22 February 2016 / Revised: 30 March 2016 / Accepted: 4 April 2016 / Published: 12 April 2016
Cited by 9 | Viewed by 1939 | PDF Full-text (1902 KB) | HTML Full-text | XML Full-text
Abstract
Phase change materials (PCMs) have been used in various fields including the materials of buildings. In this research, mixed shape-stabilized PCMs (Mixed SSPCMs) were prepared by impregnating coconut oil and n-hexadecane into exfoliated graphite nanoplatelets (xGnP) through a vacuum impregnate method. Coconut [...] Read more.
Phase change materials (PCMs) have been used in various fields including the materials of buildings. In this research, mixed shape-stabilized PCMs (Mixed SSPCMs) were prepared by impregnating coconut oil and n-hexadecane into exfoliated graphite nanoplatelets (xGnP) through a vacuum impregnate method. Coconut oil is fatty acid ester PCM which is relatively economical in comparison to other PCMs, and n-hexadecane is paraffin PCM that has high latent heat capacity. Drawbacks include leakage in a liquid state and low thermal conductivity resolved by xGnP. When preparing Mixed SSPCMs, coconut oil and n-hexadecane were impregnated at different proportions, namely 70:30, 50:50, 30:70 wt %. Mixed SSPCMs were analyzed through SEM, FT-IR, DSC, TGA and TCi. As a result, we confirmed the microstructure, chemical stability, thermal properties, thermal stability and thermal conductivity of Mixed SSPCMs. Latent heat capacity of Mixed SSPCMs were 89.06, 104.30 and 124.50 J/g while those of SSPCMs containing single PCM were 82.34 and 96.40 J/g. Thermal conductivity of Mixed SSPCMs was more than 284% higher than that of pure coconut oil and n-hexadecane. Finally, we confirmed that coconut oil and n-hexadecane were impregnated into xGnP, and the Mixed SSPCMs have high thermal durability. Full article
(This article belongs to the Special Issue Phase Change Materials (PCM))
Figures

Figure 1

Open AccessArticle
Relationship between ISO 230-2/-6 Test Results and Positioning Accuracy of Machine Tools Using LaserTRACER
Appl. Sci. 2016, 6(4), 105; https://doi.org/10.3390/app6040105
Received: 30 December 2015 / Revised: 27 March 2016 / Accepted: 29 March 2016 / Published: 12 April 2016
Cited by 3 | Viewed by 2733 | PDF Full-text (5124 KB) | HTML Full-text | XML Full-text
Abstract
To test the positioning accuracy and repeatability of the linear axes of machine tools, ISO (International Standards Organization) 230-2 and ISO 230-6 are usually adopted. Auto-tracking laser interferometers (ATLI) can perform the testing for the positioning accuracy and the repeatability including x-, [...] Read more.
To test the positioning accuracy and repeatability of the linear axes of machine tools, ISO (International Standards Organization) 230-2 and ISO 230-6 are usually adopted. Auto-tracking laser interferometers (ATLI) can perform the testing for the positioning accuracy and the repeatability including x-, y- and z-axes according to ISO 230-2 as well as xy, xz, yz, and xyz diagonal lines following ISO 230-6. LaserTRACER is a kind of ATLI. One of the steps of the ISO 230-2 and -6 tests using LaserTRACER is to determine the coordinate of the LaserTRACER with respect to the home point of the machine tool. Positioning accuracy of the machine tool causes the coordinate determined error, which might influence the test result. To check on this error, this study performs three experiments. The experiment results show that the positioning error appears on the testing results. Full article
(This article belongs to the Special Issue Selected Papers from the 2015 International Conference on Inventions)
Figures

Figure 1

Open AccessArticle
Detecting the Presence of High Water-to-Cement Ratio in Concrete Surfaces Using Highly Nonlinear Solitary Waves
Appl. Sci. 2016, 6(4), 104; https://doi.org/10.3390/app6040104
Received: 11 January 2016 / Revised: 23 February 2016 / Accepted: 18 March 2016 / Published: 11 April 2016
Cited by 15 | Viewed by 1528 | PDF Full-text (2443 KB) | HTML Full-text | XML Full-text
Abstract
We describe a nondestructive evaluation (NDE) method based on the propagation of highly nonlinear solitary waves (HNSWs) to determine the excess of water on the surface of existing concrete structures. HNSWs are induced in a one-dimensional granular chain placed in contact with the [...] Read more.
We describe a nondestructive evaluation (NDE) method based on the propagation of highly nonlinear solitary waves (HNSWs) to determine the excess of water on the surface of existing concrete structures. HNSWs are induced in a one-dimensional granular chain placed in contact with the concrete to be tested. The chain is part of a built-in transducer designed and assembled to exploit the dynamic interaction between the particles and the concrete. The hypothesis is that the interaction depends on the stiffness of the concrete and influences the time-of-flight of the solitary pulse reflected at the transducer/concrete interface. Two sets of experiments were conducted. In the first set, eighteen concrete cylinders with different water-to-cement (w/c) ratios were cast and tested in order to obtain baseline data to link the ratio to the time of flight. Then, sixteen short beams with fixed w/c ratio, but subject to water in excess at one surface, were cast. The novel NDE method was applied along with the conventional ultrasonic pulse velocity technique in order to determine advantages and limitations of the proposed approach. The results show that the time of flight detected the excess of water in the beams. In the future, the proposed method may be employed in the field to evaluate rapidly and reliably the condition of existing concrete structures and, in particular, concrete decks. Full article
Figures

Figure 1

Open AccessArticle
Research on a Linear Piezoelectric Actuator Using T-Shape Transducer to Realize High Mechanical Output
Appl. Sci. 2016, 6(4), 103; https://doi.org/10.3390/app6040103
Received: 26 February 2016 / Revised: 28 March 2016 / Accepted: 30 March 2016 / Published: 11 April 2016
Cited by 6 | Viewed by 1847 | PDF Full-text (2829 KB) | HTML Full-text | XML Full-text
Abstract
A modified large thrust ultrasonic linear motor using a T-shape configuration composed of two orthogonal sandwich-type transducers has been proposed in this paper. It is an improved version of a previous T-shape motor. The vertical transducer is used to generate the normal force [...] Read more.
A modified large thrust ultrasonic linear motor using a T-shape configuration composed of two orthogonal sandwich-type transducers has been proposed in this paper. It is an improved version of a previous T-shape motor. The vertical transducer is used to generate the normal force between the driving foot and slider, while the other push-pull–type horizontal transducer is applied to generate driving force to push the working platform. By superimposing the two longitudinal vibrations, the proposed motor generates an elliptical movement on the driving foot. In order to improve the vibration characteristics and amplify the driving vibration amplitude, the shape of the driving foot and horn have been redesigned and optimized. The finite element method (FEM) is used to adjust the structural parameters to degenerate the two working mode frequencies. The prototype has been fabricated and its mechanical output ability has been measured. The output characteristics of the modified motor, compared with the previous T-shape motor, achieve a relatively high level. The typical no-load speed and maximum output thrust of the prototype are 0.83 m/s and 56 N under an exciting voltage of 150 Vrms. Full article
(This article belongs to the Special Issue Ferroelectric Ceramics)
Figures

Figure 1

Open AccessArticle
Numerical Models for the Assessment of Historical Masonry Structures and Materials, Monitored by Acoustic Emission
Appl. Sci. 2016, 6(4), 102; https://doi.org/10.3390/app6040102
Received: 9 December 2015 / Revised: 7 March 2016 / Accepted: 18 March 2016 / Published: 8 April 2016
Cited by 6 | Viewed by 1871 | PDF Full-text (10510 KB) | HTML Full-text | XML Full-text
Abstract
The paper reviews some recent numerical applications for the interpretation and exploitation of acoustic emission (AE) monitoring results obtained from historical masonry structures and materials. Among possible numerical techniques, the finite element method and the distinct method are considered. The analyzed numerical models [...] Read more.
The paper reviews some recent numerical applications for the interpretation and exploitation of acoustic emission (AE) monitoring results obtained from historical masonry structures and materials. Among possible numerical techniques, the finite element method and the distinct method are considered. The analyzed numerical models cover the entire scale range, from microstructure and meso-structure, up to full-size real structures. The micro-modeling includes heterogeneous concrete-like materials, but mainly focuses on the masonry texture meso-structure, where each brick and mortar joint is modeled singularly. The full-size models consider the different typology of historical structures such as masonry towers, cathedrals and chapels. The main difficulties and advantages of the different numerical approaches, depending on the problem typology and scale, are critically analyzed. The main insight we can achieve from micro and meso numerical modeling concerns the scaling of AE as a function of volume and time, since it is also able to simulate the b-value temporal evolution as the damage spread into the structure. The finite element modeling of the whole structure provides useful hints for the optimal placement of the AE sensors, while the combination of AE monitoring results is crucial for a reliable assessment of structural safety. Full article
Figures

Figure 1

Open AccessArticle
Probabilistic Fatigue Life Prediction of Bridge Cables Based on Multiscaling and Mesoscopic Fracture Mechanics
Appl. Sci. 2016, 6(4), 99; https://doi.org/10.3390/app6040099
Received: 22 October 2015 / Revised: 21 February 2016 / Accepted: 9 March 2016 / Published: 7 April 2016
Cited by 5 | Viewed by 2045 | PDF Full-text (7215 KB) | HTML Full-text | XML Full-text
Abstract
Fatigue fracture of bridge stay-cables is usually a multiscale process as the crack grows from micro-scale to macro-scale. Such a process, however, is highly uncertain. In order to make a rational prediction of the residual life of bridge cables, a probabilistic fatigue approach [...] Read more.
Fatigue fracture of bridge stay-cables is usually a multiscale process as the crack grows from micro-scale to macro-scale. Such a process, however, is highly uncertain. In order to make a rational prediction of the residual life of bridge cables, a probabilistic fatigue approach is proposed, based on a comprehensive vehicle load model, finite element analysis and multiscaling and mesoscopic fracture mechanics. Uncertainties in both material properties and external loads are considered. The proposed method is demonstrated through the fatigue life prediction of cables of the Runyang Cable-Stayed Bridge in China, and it is found that cables along the bridge spans may have significantly different fatigue lives, and due to the variability, some of them may have shorter lives than those as expected from the design. Full article
Figures

Figure 1

Open AccessArticle
Real-Time Compensation for Thermal Errors of the Milling Machine
Appl. Sci. 2016, 6(4), 101; https://doi.org/10.3390/app6040101
Received: 30 November 2015 / Revised: 25 March 2016 / Accepted: 28 March 2016 / Published: 7 April 2016
Cited by 4 | Viewed by 1971 | PDF Full-text (5044 KB) | HTML Full-text | XML Full-text
Abstract
This paper is focused on developing a compensation module for reducing the thermal errors of a computer numerical control (CNC) milling machine. The thermal induced displacement variations of machine tools are a vital problem that causes positioning errors to be over than 65%. [...] Read more.
This paper is focused on developing a compensation module for reducing the thermal errors of a computer numerical control (CNC) milling machine. The thermal induced displacement variations of machine tools are a vital problem that causes positioning errors to be over than 65%. To achieve a high accuracy of machine tools, it is important to find the effective methods for reducing the thermal errors. To this end, this study first used 14 temperature sensors to examine the real temperature fields around the machine, from which four points with high sensitivity to temperature rise were selected as the major locations for creating the representative thermal model. With the model, the compensation system for controlling the displacement variation was developed. The proposed model has been applied to the milling machine. Current results show that the displacement variations on the x- and y-axes and the position error at the tool center were controlled within 20 µm when the compensation system was activated. The feasibility of the compensation system was successfully demonstrated in application on the milling operation. Full article
Figures

Figure 1

Open AccessArticle
Adequacy of Technical and Commercial Alternatives Applied to Machine Tool Verification Using Laser Tracker
Appl. Sci. 2016, 6(4), 100; https://doi.org/10.3390/app6040100
Received: 4 March 2016 / Revised: 23 March 2016 / Accepted: 25 March 2016 / Published: 7 April 2016
Cited by 4 | Viewed by 1871 | PDF Full-text (4500 KB) | HTML Full-text | XML Full-text
Abstract
Besides presenting a volumetric verification technique that allows characterization of the different geometric errors of a machine tool (MT) depending on its kinematic chain and geometry through a kinematic model, this paper investigates the influence of measurement tools and techniques available on the [...] Read more.
Besides presenting a volumetric verification technique that allows characterization of the different geometric errors of a machine tool (MT) depending on its kinematic chain and geometry through a kinematic model, this paper investigates the influence of measurement tools and techniques available on the final accuracy of the MT. Volumetric verification based on a laser tracker (LT) relates the coordinates of the tool with the coordinates of the LT, including it into the kinematic model. Using a non-lineal optimization process, approximation functions that characterize the joint influence of MT geometric errors are obtained. However, measurement data will be affected by previous compensation of the MT, the accuracy of the measurement system, LT measurement technology, the type of retroreflector used, and techniques used to improve data accuracy, among other sources of errors. This paper studies the adequacy of different commercial alternatives such as: retroreflectors, LTs from different manufacturers, etc., that can be applied in MT verification using a long-range MT. As the accuracy is strongly affected by the uncertainty of its angular encoders, the multilateration technique tries to improve data accuracy using only LT radial information. Nonetheless, a new bundle adjustment which uses radial and angular information is presented in current metrology software. This paper studies both techniques and analyzes their adequacy for MT verification too. Full article
Figures

Figure 1

Open AccessArticle
Hybrid Robust Control Law with Disturbance Observer for High-Frequency Response Electro-Hydraulic Servo Loading System
Appl. Sci. 2016, 6(4), 98; https://doi.org/10.3390/app6040098
Received: 23 December 2015 / Revised: 25 March 2016 / Accepted: 28 March 2016 / Published: 6 April 2016
Cited by 8 | Viewed by 2345 | PDF Full-text (9808 KB) | HTML Full-text | XML Full-text
Abstract
Addressing the simulating issue of the helicopter-manipulating booster aerodynamic load with high-frequency dynamic load superimposed on a large static load, this paper studies the design of the robust controller for the electro-hydraulic loading system to realize the simulation of this kind of load. [...] Read more.
Addressing the simulating issue of the helicopter-manipulating booster aerodynamic load with high-frequency dynamic load superimposed on a large static load, this paper studies the design of the robust controller for the electro-hydraulic loading system to realize the simulation of this kind of load. Firstly, the equivalent linear model of the electro-hydraulic loading system under assumed parameter uncertainty is established. Then, a hybrid control scheme is proposed for the loading system. This control scheme consists of a constant velocity feed-forward compensator, a robust inner loop compensator based on disturbance observer and a robust outer loop feedback controller. The constant velocity compensator eliminates most of the extraneous force at first, and then the double-loop cascade composition control strategy is employed to design the compensated system. The disturbance observer–based inner loop compensator further restrains the disturbances including the remaining extraneous force, and makes the actual plant tracking a nominal model approximately in a certain frequency range. The robust outer loop controller achieves the desired force-tracking performance, and guarantees system robustness in the high frequency region. The optimized low-pass filter Q(s) is designed by using the H∞ mixed sensitivity optimization method. The simulation results show that the proposed hybrid control scheme and controller can effectively suppress the extraneous force and improve the robustness of the electro-hydraulic loading system. Full article
Figures

Figure 1

Open AccessArticle
Development of an Abbe Error Free Micro Coordinate Measuring Machine
Appl. Sci. 2016, 6(4), 97; https://doi.org/10.3390/app6040097
Received: 31 January 2016 / Revised: 21 March 2016 / Accepted: 25 March 2016 / Published: 5 April 2016
Cited by 7 | Viewed by 2611 | PDF Full-text (4300 KB) | HTML Full-text | XML Full-text
Abstract
A micro Coordinate Measuring Machine (CMM) with the measurement volume of 50 mm × 50 mm × 50 mm and measuring accuracy of about 100 nm (2σ) has been developed. In this new micro CMM, an XYZ stage, which is driven by three [...] Read more.
A micro Coordinate Measuring Machine (CMM) with the measurement volume of 50 mm × 50 mm × 50 mm and measuring accuracy of about 100 nm (2σ) has been developed. In this new micro CMM, an XYZ stage, which is driven by three piezo-motors in X, Y and Z directions, can achieve the drive resolution of about 1 nm and the stroke of more than 50 mm. In order to reduce the crosstalk among X-, Y- and Z-stages, a special mechanical structure, which is called co-planar stage, is introduced. The movement of the stage in each direction is detected by a laser interferometer. A contact type of probe is adopted for measurement. The center of the probe ball coincides with the intersection point of the measuring axes of the three laser interferometers. Therefore, the metrological system of the CMM obeys the Abbe principle in three directions and is free from Abbe error. The CMM is placed in an anti-vibration and thermostatic chamber for avoiding the influence of vibration and temperature fluctuation. A series of experimental results show that the measurement uncertainty within 40 mm among X, Y and Z directions is about 100 nm (2σ). The flatness of measuring face of the gauge block is also measured and verified the performance of the developed micro CMM. Full article
Figures

Figure 1

Open AccessArticle
Multi-Variable, Multi-Layer Graphical Knowledge Unit for Storing and Representing Density Clusters of Multi-Dimensional Big Data
Appl. Sci. 2016, 6(4), 96; https://doi.org/10.3390/app6040096
Received: 25 October 2015 / Revised: 15 March 2016 / Accepted: 15 March 2016 / Published: 5 April 2016
Viewed by 2055 | PDF Full-text (4483 KB) | HTML Full-text | XML Full-text
Abstract
A multi-variable visualization technique on a 2D bitmap for big data is introduced. If A and B are two data points that are represented using two similar shapes with m pixels, where each shape is colored with RGB color of (0, 0, k [...] Read more.
A multi-variable visualization technique on a 2D bitmap for big data is introduced. If A and B are two data points that are represented using two similar shapes with m pixels, where each shape is colored with RGB color of (0, 0, k), when AB ≠ ɸ, adding the color of AB gives higher color as (0, 0, 2k) and the highlight as a high density cluster, where RGB stands for Red, Green, Blue and k is the blue color. This is the hypothesis behind the single variable graphical knowledge unit (GKU), which uses the entire bit range of a pixel for a single variable. Instead, the available bit range of a pixel is split, and a pixel can be used for representing multiple variables (multi-variables). However, this will limit the bit block for single variables and limit the amount of overlapping. Using the same size k (>1) bitmaps (multi-layers) will increase the number of bits per variable (BPV), where each (x, y) of an individual layer represents the same data point. Then, one pixel in a four-layer GKU is capable of showing more than four billion overlapping ones when BPV = 8 bits (2(BPV × number of layers)) Then, the 32-bit pixel format allows the representation of a maximum of up to four dependent variables against one independent variable. Then, a four-layer GKU of w width and h height has the capacity of representing a maximum of (2(BPV × number of layers)) × m × w × h overlapping occurrences. Full article
Figures

Figure 1

Open AccessArticle
Biodegradation of Unsymmetrical Dimethylhydrazine in Solution and Soil by Bacteria Isolated from Activated Sludge
Appl. Sci. 2016, 6(4), 95; https://doi.org/10.3390/app6040095
Received: 25 February 2016 / Revised: 22 March 2016 / Accepted: 23 March 2016 / Published: 31 March 2016
Cited by 1 | Viewed by 2023 | PDF Full-text (4690 KB) | HTML Full-text | XML Full-text
Abstract
The biodegradation effect and pathway of unsymmetrical dimethylhydrazine (UDMH), which is a major rocket propellant with highly toxic properties, with two strains isolated from the acclimated activated sludge were investigated in solution and in soil. The results demonstrated that Stenotrophomonas sp. M12 (M12) [...] Read more.
The biodegradation effect and pathway of unsymmetrical dimethylhydrazine (UDMH), which is a major rocket propellant with highly toxic properties, with two strains isolated from the acclimated activated sludge were investigated in solution and in soil. The results demonstrated that Stenotrophomonas sp. M12 (M12) was able to degrade UDMH of 50 mg·L−1 as the sole carbon source in aqueous mineral salt medium (MSM), but could not degrade UDMH in soil. Comamonas sp. P4 (P4) barely degraded UDMH of 50 mg·L−1 as the sole carbon source in aqueous MSM, but the degrading capacity of P4 could be improved by the addition of an extra carbon source. Meanwhile, P4 was able to degrade UDMH of 100–600 mg·kg−1 in the soil. The degradation of UDMH in the soil was influenced by organic matter, autochthonous microorganisms, and metal ions. UDMH could inhibit metabolism of M12 and P4, and the inhibition influence was more severe in aqueous MSM than in soil. Oxygen content was important for M12 biodegrading UDMH, and co-metabolism helped P4 to self-detoxify and self-recover. The main intermediates of UDMH were identified by Gas Chromatography-Mass Spectrometer (GC/MS) qualitative analysis, and the concentrations of UDMH and its important transformation products were determined in solution and soil. According to the determination results, the synchronous degradation theory was proposed, and the degradation pathway was discussed. Full article
Figures

Figure 1

Open AccessReview
Application of Single-Electron Transistor to Biomolecule and Ion Sensors
Appl. Sci. 2016, 6(4), 94; https://doi.org/10.3390/app6040094
Received: 30 December 2015 / Revised: 1 March 2016 / Accepted: 18 March 2016 / Published: 31 March 2016
Cited by 3 | Viewed by 1388 | PDF Full-text (4153 KB) | HTML Full-text | XML Full-text
Abstract
The detection and quantification of chemical and biological species are the key technology in many areas of healthcare and life sciences. Field-effect transistors (FETs) are sophisticated devices used for the label-free and real-time detection of charged species. Nanowire channels were used for highly [...] Read more.
The detection and quantification of chemical and biological species are the key technology in many areas of healthcare and life sciences. Field-effect transistors (FETs) are sophisticated devices used for the label-free and real-time detection of charged species. Nanowire channels were used for highly sensitive detections of target ion or biomolecule in FET sensors, however, even significantly higher detection sensitivity is required in FET sensors, especially when the target species are dilute in concentration. Since the high detection sensitivity of nanowire FET sensors is due to the suppression of the carrier percolation effect through the channel, the channel width has to be decreased, leading to the decrease in the transconductance (gm). Therefore, gm should be increased while keeping channel width narrow to obtain higher sensitivity. Single-electron transistors (SETs) are a promising candidate for achieving higher detection sensitivity due to the Coulomb oscillations. However, no reports of an SET-based ion sensor or biosensor existed, probably because of the difficulty of the room-temperature operation of SETs. Recently, room-temperature SET operations were carried out using a Si multiple-island channel structure. This review introduces the mechanism of ultra-sensitive detection of ions and biomolecules based on an SET sensor and the experimental results. Full article
(This article belongs to the Special Issue Applied Single-Electron Transistors)
Figures

Figure 1

Open AccessArticle
The Development of an Optimal Control Strategy for a Series Hydraulic Hybrid Vehicle
Appl. Sci. 2016, 6(4), 93; https://doi.org/10.3390/app6040093
Received: 30 November 2015 / Revised: 12 March 2016 / Accepted: 17 March 2016 / Published: 28 March 2016
Cited by 3 | Viewed by 2325 | PDF Full-text (4291 KB) | HTML Full-text | XML Full-text
Abstract
In this work, a Truck Class II series hydraulic hybrid model is established. Dynamic Programming (DP) methodology is applied to derive the optimal power-splitting factor for the hybrid system for preselected driving schedules. Implementable rules are derived by extracting the optimal trajectory features [...] Read more.
In this work, a Truck Class II series hydraulic hybrid model is established. Dynamic Programming (DP) methodology is applied to derive the optimal power-splitting factor for the hybrid system for preselected driving schedules. Implementable rules are derived by extracting the optimal trajectory features from a DP scheme. The system behaviors illustrate that the improved control strategy gives a highly effective operation region for the engine and high power density characteristics for the hydraulic components. Full article
Figures

Figure 1

Open AccessArticle
A FBG Intensity Modulation System Combined with an Optical Whispering Gallery Mode Edge Filter
Appl. Sci. 2016, 6(4), 92; https://doi.org/10.3390/app6040092
Received: 26 November 2015 / Revised: 3 March 2016 / Accepted: 21 March 2016 / Published: 28 March 2016
Cited by 4 | Viewed by 1812 | PDF Full-text (5079 KB) | HTML Full-text | XML Full-text
Abstract
In this study, we demonstrated an edge filter–based fiber Bragg grating (FBG) intensity modulation system to realize strain measurement. In order to establish a precise and highly sensitive intensity modulation system, we utilized a bent single-mode fiber to induce whispering gallery mode (WGM) [...] Read more.
In this study, we demonstrated an edge filter–based fiber Bragg grating (FBG) intensity modulation system to realize strain measurement. In order to establish a precise and highly sensitive intensity modulation system, we utilized a bent single-mode fiber to induce whispering gallery mode (WGM) interference as an edge filter and combined that with a FBG sensor. The interference spectra of the attenuation band for the WGM edge filter were tuned by adjusting the bending radii. In addition, we compared and analyzed the signals from the proposed vibration interrogating system and a strain gauge. The measured voltage signals from the proposed interrogation system were in close agreement with measured strains of the strain gauge. The experimental results showed that when the resonant wavelength of the WGM edge filter was 1535.10 nm, the filtration was better and the noise was lower within 100 Hz. Moreover, as the frequency of piezoelectric transducer (PZT) was at 400 and 1000 Hz, the better signal-to-noise ratios (SNRs) of 28.54 and 25.97 were measured at wavelength 1542.05 nm of the edge filter. Full article
Figures

Figure 1

Open AccessArticle
SDNPS: A Load-Balanced Topic-Based Publish/Subscribe System in Software-Defined Networking
Appl. Sci. 2016, 6(4), 91; https://doi.org/10.3390/app6040091
Received: 31 December 2015 / Revised: 12 March 2016 / Accepted: 14 March 2016 / Published: 24 March 2016
Cited by 7 | Viewed by 1832 | PDF Full-text (849 KB) | HTML Full-text | XML Full-text
Abstract
Publish/subscribe systems on the traditional Internet suffer from poor scalability and high delay in the face of the Internet of Things (IoT) environment. Being customizable, the paradigm of software-defined networking (SDN) provides a chance to establish an IoT-specific network. In this paper, we [...] Read more.
Publish/subscribe systems on the traditional Internet suffer from poor scalability and high delay in the face of the Internet of Things (IoT) environment. Being customizable, the paradigm of software-defined networking (SDN) provides a chance to establish an IoT-specific network. In this paper, we propose an SDN-based publish/subscribe system named SDNPS, which can construct and fine-tune topic-connected overlays for the sake of disseminating events efficiently and non-redundantly based on a global topology overview. It organizes topics as a Huffman-like topic tree and codes them into binary strings so that filtering and forwarding events can be operated directly on SDN-configurable switches, which helps to reduce end-to-end latency. This hierarchical organization form of topic tree makes it possible to incrementally construct and store overlays, which contribute to reducing the time and space complexity of routing computation. More specifically, it achieves a better tradeoff between load-balancing of the overall optimization objective and the minimal forwarding cost of per-topic overlay. Full article
(This article belongs to the Special Issue Smart Grid: Convergence and Interoperability)
Figures

Figure 1

Open AccessArticle
Simulation of a Narrowband Power Line Communications System over Medium Voltage
Appl. Sci. 2016, 6(4), 90; https://doi.org/10.3390/app6040090
Received: 28 September 2015 / Revised: 10 March 2016 / Accepted: 14 March 2016 / Published: 23 March 2016
Cited by 2 | Viewed by 1734 | PDF Full-text (847 KB) | HTML Full-text | XML Full-text
Abstract
Narrowband Power Line Communications (NB-PLCs) are investigated as an alternative option for transferring low rate smart grid (SG) data via Medium Voltage (MV) power lines. In this framework, two variants of orthogonal frequency division multiplexing are examined, namely Filtered-OFDM (F-OFDM) and Wavelet-OFDM (W-OFDM), [...] Read more.
Narrowband Power Line Communications (NB-PLCs) are investigated as an alternative option for transferring low rate smart grid (SG) data via Medium Voltage (MV) power lines. In this framework, two variants of orthogonal frequency division multiplexing are examined, namely Filtered-OFDM (F-OFDM) and Wavelet-OFDM (W-OFDM), in an attempt to determine which of them is capable of transmitting low rate SG data to greater distances over non-branched MV power lines. The reach of NB-PLC signals via MV power lines is estimated, taking into account the transfer function of the relevant PLC channels and noise mechanisms as well as the specific features of the two modulation options under consideration. Simulations show that NB-PLC transmission constitutes a technically feasible and economically affordable option for exchanging low rate data with remote SG nodes dispersed over the MV grid. Moreover, simulations show that F-OFDM allows low rate data transmission to considerably greater distances compared to W-OFDM. Full article
Figures

Figure 1

Appl. Sci. EISSN 2076-3417 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top