Next Issue
Previous Issue

Table of Contents

Appl. Sci., Volume 8, Issue 8 (August 2018)

  • 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.
Cover Story (view full-size image) This array of ring oscillators was fabricated using a process based on inkjet printing. By [...] Read more.
View options order results:
result details:
Displaying articles 1-201
Export citation of selected articles as:
Open AccessFeature PaperArticle Optimal Operation Method for Distribution Systems Considering Distributed Generators Imparted with Reactive Power Incentive
Appl. Sci. 2018, 8(8), 1411; https://doi.org/10.3390/app8081411
Received: 19 July 2018 / Revised: 15 August 2018 / Accepted: 17 August 2018 / Published: 20 August 2018
Viewed by 684 | PDF Full-text (924 KB) | HTML Full-text | XML Full-text
Abstract
In order to solve urgent energy and environmental problems, it is essential to carry out high installation of distributed generation using renewable energy sources (RESs) and environmentally-friendly storage technologies. However, a high penetration of RESs usually leads to a conventional power system unreliability,
[...] Read more.
In order to solve urgent energy and environmental problems, it is essential to carry out high installation of distributed generation using renewable energy sources (RESs) and environmentally-friendly storage technologies. However, a high penetration of RESs usually leads to a conventional power system unreliability, instability and low power quality. Therefore, this paper proposes a reactive power control method based on the demand response (DR) program to achieve a safe, reliable and stable power system. This program does not enforce a change in the active power usage of the customer, but provides a reactive power incentive to customers who participate in the cooperative control of the distribution company (DisCo). Customers can achieve a reduction in their total energy purchase by gaining a reactive power incentive, whilst the DisCo can achieve a reduction of its total procurement of equipment and distribution losses. An optimal control schedule is calculated using the particle swarm optimization (PSO) method, and also in order to avoid over-control, a modified scheduling method that is a dual scheduling method has been adopted in this paper. The effectiveness of the proposed method was verified by numerical simulation. Then, simulation results have been analyzed by case studies. Full article
(This article belongs to the Special Issue Renewable Energy 2018)
Figures

Figure 1

Open AccessFeature PaperArticle 3D Printed High Gain Complementary Dipole/Slot Antenna Array
Appl. Sci. 2018, 8(8), 1410; https://doi.org/10.3390/app8081410
Received: 31 July 2018 / Revised: 13 August 2018 / Accepted: 15 August 2018 / Published: 20 August 2018
Viewed by 902 | PDF Full-text (2381 KB) | HTML Full-text | XML Full-text
Abstract
By employing the complementary dipole antenna concept to the normal waveguide fed slot radiator, an improved antenna element with wide impedance bandwidth and symmetrical radiation patterns is developed. This is achieved by mounting two additional metallic cuboids on the top of the slot
[...] Read more.
By employing the complementary dipole antenna concept to the normal waveguide fed slot radiator, an improved antenna element with wide impedance bandwidth and symmetrical radiation patterns is developed. This is achieved by mounting two additional metallic cuboids on the top of the slot radiator, which is equivalent to adding an electric dipole on top of the magnetic dipole due to the slot radiator. Then, a high-gain antenna array was designed based on the improved element and fabricated, using 3D printing technology, with stable frequency characteristics operated at around 28 GHz. This was followed by metallization via electroplating. Analytical results agree well with the experimental results. The measured operating frequency range for the reflection coefficient ≤−15 dB is from 25.7 GHz to 29.8 GHz; its corresponding fractional impedance bandwidth is 14.8%. The measured gain is approximately 32 dBi, with the 3 dB beamwidth around 4°. Full article
(This article belongs to the Special Issue 3D Printed Antennas)
Figures

Figure 1

Open AccessArticle Relay-Enabled Task Offloading Management for Wireless Body Area Networks
Appl. Sci. 2018, 8(8), 1409; https://doi.org/10.3390/app8081409
Received: 9 July 2018 / Revised: 13 August 2018 / Accepted: 16 August 2018 / Published: 20 August 2018
Viewed by 534 | PDF Full-text (1597 KB) | HTML Full-text | XML Full-text
Abstract
Inspired by the recent developments of the Internet of Things (IoT) relay and mobile edge computing (MEC), a hospital/home-based medical monitoring framework is proposed, in which the intensive computing tasks from the implanted sensors can be efficiently executed by on-body wearable devices or
[...] Read more.
Inspired by the recent developments of the Internet of Things (IoT) relay and mobile edge computing (MEC), a hospital/home-based medical monitoring framework is proposed, in which the intensive computing tasks from the implanted sensors can be efficiently executed by on-body wearable devices or a coordinator-based MEC (C-MEC). In this paper, we first propose a wireless relay-enabled task offloading mechanism that consists of a network model and a computation model. Moreover, to manage the computation resources among all relays, a task offloading decision model and the best task offloading recipient selection function is given. The performance evaluation considers different computation schemes under the predetermined link quality condition regarding the selected vital quality of service (QoS) metrics. After demonstrating the channel characterization and network topology, the performance evaluation is implemented under different scenarios regarding the network lifetime of all relays, network residual energy status, total number of locally executed packets, path loss (PL), and service delay. The results show that data transmission without the offloading scheme outperforms the offload-based technique regarding network lifetime. Moreover, the high computation capacity scenario achieves better performance regarding PL and the total number of locally executed packets. Full article
(This article belongs to the Special Issue Smart Environment and Healthcare)
Figures

Figure 1

Open AccessArticle A Single-Stage High-Power Factor Converter with Synchronized Self-Excited Technique for LED Lighting
Appl. Sci. 2018, 8(8), 1408; https://doi.org/10.3390/app8081408
Received: 16 July 2018 / Revised: 3 August 2018 / Accepted: 16 August 2018 / Published: 20 August 2018
Cited by 1 | Viewed by 693 | PDF Full-text (5151 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes a single-stage, high power-factor light-emitting diode (LED) driver with a self-excited control scheme for the power switches. The self-excited mechanism is accomplished by fetching the driving voltages from a center-tapped transformer. The frequency of the driving voltages is exactly the
[...] Read more.
This paper proposes a single-stage, high power-factor light-emitting diode (LED) driver with a self-excited control scheme for the power switches. The self-excited mechanism is accomplished by fetching the driving voltages from a center-tapped transformer. The frequency of the driving voltages is exactly the same as the resonant frequency of the resonant converter, thus synchronizing the resonant frequency with the switching frequency and achieving zero-voltage switching (ZVS) and zero-current switching (ZCS) of power switches. The circuit topology is mainly composed of a half-bridge LC resonant converter, along with a boost-type power-factor corrector (PFC) to fulfill the single-stage structure, meaning that the presented LED driver possesses high power-factor features and low switching loss. Finally, a 40 W prototype circuit is implemented and tested, and the experimental results exhibit a satisfactory performance. Full article
(This article belongs to the Special Issue Smart Lighting)
Figures

Figure 1

Open AccessArticle Acoustic Emission/Seismicity at Depth Beneath an Artificial Lake after the 2011 Tohoku Earthquake
Appl. Sci. 2018, 8(8), 1407; https://doi.org/10.3390/app8081407
Received: 20 July 2018 / Revised: 10 August 2018 / Accepted: 16 August 2018 / Published: 20 August 2018
Viewed by 552 | PDF Full-text (2855 KB) | HTML Full-text | XML Full-text
Abstract
Acoustic emission (AE)/seismicity activity increased near the city of Sendai, Japan, after the 11 March 2011 Tohoku earthquake in a newly seismically active region near the Nagamachi-Rifu fault, which caused a magnitude 5.0 earthquake in 1998. The source of this activity was around
[...] Read more.
Acoustic emission (AE)/seismicity activity increased near the city of Sendai, Japan, after the 11 March 2011 Tohoku earthquake in a newly seismically active region near the Nagamachi-Rifu fault, which caused a magnitude 5.0 earthquake in 1998. The source of this activity was around 12 km beneath an artificial lake. At the same time, activity on the Nagamachi-Rifu fault nearly ceased. More than 1550 micro-earthquakes were observed between 11 March 2011 and 1 August 2012, of which 63% exhibited similar waveforms and defined 64 multiplets. It appears that crustal extension of about 2 m during the Tohoku earthquake and additional extension of about 1 m during the following year changed the stress field in this region, thus generating micro-earthquakes and controlling their frequency. However, it has been presumed that crustal movement during the Tohoku earthquake did not affect the direction of principal stress, and that these events induced repeated quasi-static slips at asperities and the resultant micro-earthquakes. Full article
Figures

Figure 1

Open AccessArticle Improving the Gate-Induced Drain Leakage and On-State Current of Fin-Like Thin Film Transistors with a Wide Drain
Appl. Sci. 2018, 8(8), 1406; https://doi.org/10.3390/app8081406
Received: 23 June 2018 / Revised: 9 August 2018 / Accepted: 15 August 2018 / Published: 20 August 2018
Viewed by 505 | PDF Full-text (3201 KB) | HTML Full-text | XML Full-text
Abstract
Polycrystalline silicon (poly-Si) thin film transistors (TFT) with a tri-gate fin-like structure and wide drain were designed and simulated to improve gate-induced drain leakage (GIDL), ON-state current, and breakdown voltage. The GIDL of fin-like TFTs (FinTFTs) examined in this study was dominated by
[...] Read more.
Polycrystalline silicon (poly-Si) thin film transistors (TFT) with a tri-gate fin-like structure and wide drain were designed and simulated to improve gate-induced drain leakage (GIDL), ON-state current, and breakdown voltage. The GIDL of fin-like TFTs (FinTFTs) examined in this study was dominated by longitudinal band-to-band tunneling (L-BTBT). Extending the wide drain can effectively suppress the longitudinal electric field near the drain and improve L-BTBT GIDL and breakdown. In addition, a wider drain can lead to a large cross section in the current path and improve the ON-state current. FinTFTs with wide drain exhibit a low GIDL, a high ON-state current, and high breakdown voltage, while maintaining favorable gate controllability. Full article
(This article belongs to the Special Issue Selected Papers from the 2017 International Conference on Inventions)
Figures

Figure 1

Open AccessFeature PaperArticle Effects of Natural Antioxidant Agents on the Bitumen Aging Process: An EPR and Rheological Investigation
Appl. Sci. 2018, 8(8), 1405; https://doi.org/10.3390/app8081405
Received: 24 July 2018 / Revised: 14 August 2018 / Accepted: 15 August 2018 / Published: 19 August 2018
Cited by 1 | Viewed by 615 | PDF Full-text (1785 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Bitumen aging is the major factor contributing to the deterioration of the road pavement. Oxidation and volatilization are generally considered as the most important phenomena affecting aging in asphalt paving mixtures. The present study was carried out to investigate whether various antioxidants provided
[...] Read more.
Bitumen aging is the major factor contributing to the deterioration of the road pavement. Oxidation and volatilization are generally considered as the most important phenomena affecting aging in asphalt paving mixtures. The present study was carried out to investigate whether various antioxidants provided by natural resources such as phospholipids, ascorbic acid as well as lignin from rice husk, could be used to reduce age hardening in asphalt binders. A selected bituminous material was modified by adding 2% w/w of the anti-aging natural additives and subjected to accelerated oxidative aging regimes according to the Rolling Thin Film Oven Test (RTFOT) method. The effects of aging were evaluated based on changes in sol-gel transition temperature of modified bitumens measured through Dynamic Shear Rheology (DSR). Moreover, changes of Electron Paramagnetic Resonance (EPR) spectra were monitored on the bituminous fractions asphaltene and maltene separated by solvent extraction upon oxidative aging. The phospholipids-treated binder exhibited the highest resistance to oxidation and the lowest age-hardening effect compared to the other tested anti-oxidants. The combination of EPR and DSR techniques represents a promising method for elucidating the changes in associated complex properties of bitumen fractions promoted by addition of free radical scavengers borrowed by green resources. Full article
(This article belongs to the Section Materials)
Figures

Figure 1

Open AccessArticle An Experimental Study of the Leakage Mechanism in Static Seals
Appl. Sci. 2018, 8(8), 1404; https://doi.org/10.3390/app8081404
Received: 18 July 2018 / Revised: 16 August 2018 / Accepted: 16 August 2018 / Published: 19 August 2018
Viewed by 543 | PDF Full-text (935 KB) | HTML Full-text | XML Full-text
Abstract
This paper investigates the fluidic leak rate through sealing contact surfaces by comparison between model calculation and experiment measurement. The focus is on an experimental device designed to measure the leak rate of the static seals with a simpler structure, smaller errors, stronger
[...] Read more.
This paper investigates the fluidic leak rate through sealing contact surfaces by comparison between model calculation and experiment measurement. The focus is on an experimental device designed to measure the leak rate of the static seals with a simpler structure, smaller errors, stronger stability, and more functions. Using the device, experiments were carried out to four test pieces with different surface characteristics, whose leak rates were measured separately. Compared with the calculation results obtained from the fractal surface leak rate prediction model, the correctness and the application range of the model were verified, and the effects of different surface topographies and material properties of the four test pieces on the leak rate were analyzed as well. The experimental device was also used to perform single-factor comparison experiments, which were then combined with the theoretical prediction model to analyze the effects of the sealing surface contact load, fluid pressure, and surface apparent size on the leak rate, so that theoretical support and experimental evidence for selecting the parameters of sealing device was provided. Full article
Figures

Figure 1

Open AccessArticle Silica Pillared Montmorillonites as Possible Adsorbents of Antibiotics from Water Media
Appl. Sci. 2018, 8(8), 1403; https://doi.org/10.3390/app8081403
Received: 18 July 2018 / Revised: 14 August 2018 / Accepted: 16 August 2018 / Published: 19 August 2018
Viewed by 490 | PDF Full-text (4776 KB) | HTML Full-text | XML Full-text
Abstract
In this work, three silica pillared clays (Si-PILC) were synthetized, characterized, and evaluated as possible adsorbents of ciprofloxacin (CPX) and tetracycline (TC) form alkaline aqueous media. The pillared clays obtained showed significant increases in their specific surface areas (SBET) and micropore
[...] Read more.
In this work, three silica pillared clays (Si-PILC) were synthetized, characterized, and evaluated as possible adsorbents of ciprofloxacin (CPX) and tetracycline (TC) form alkaline aqueous media. The pillared clays obtained showed significant increases in their specific surface areas (SBET) and micropore volumes (Vμp) regarding the raw material, resulting in microporosity percentages higher than 57% in all materials. The studies of CPX and TC removal using pillared clays were compared with the natural clay and showed that the Si-PILC adsorption capacities have a strong relationship with their porous structures. The highest adsorption capacities were obtained for CPX on Si-PILC due to the lower molecular size of CPX respect to the TC molecule, favoring the interaction between the CPX and the pillars adsorption sites. Tetracycline adsorption on silica pillared clays evidenced that for this molecule the porous structure limits the interaction between the TCH and the pillars, decreasing their adsorption capacities. However, the results obtained for both antibiotics suggested that their negative species interact with adsorption sites on the pillared structure by adsorption mechanisms that involve inner-sphere complex formation as well as van der Waals interactions. The adsorption mechanism proposed for the anionic species on Si-PILC could be considered mainly as negative cooperative phenomena where firstly there is a hydrophobic effect followed by other interactions, such as der Waals or inner-sphere complex formation. Full article
(This article belongs to the Special Issue Nanoporous Materials and Their Applications)
Figures

Graphical abstract

Open AccessFeature PaperCommunication Conformal Titanyl Phosphate Surface Passivation for Enhancing Photocatalytic Activity
Appl. Sci. 2018, 8(8), 1402; https://doi.org/10.3390/app8081402
Received: 30 July 2018 / Revised: 15 August 2018 / Accepted: 17 August 2018 / Published: 19 August 2018
Viewed by 613 | PDF Full-text (1443 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A conformal titanyl phosphate passivation with the thickness of ca. 5 nm on the surface of TiO2 nanoparticles for enhancing the photocatalytic degradation of organic pollutants and hydrogen production is described. The phosphate anion species bound to the surface of TiO2
[...] Read more.
A conformal titanyl phosphate passivation with the thickness of ca. 5 nm on the surface of TiO2 nanoparticles for enhancing the photocatalytic degradation of organic pollutants and hydrogen production is described. The phosphate anion species bound to the surface of TiO2 promote the favorable kinetics of photocatalytic activity and influence the catalytic reaction pathway. By using a facile surfactant-assisted sol-gel process, the surface defects of TiO2 associated with deep traps was reduced and passivated by the phosphate anion species to form the titanyl phosphate. The strong bonds between the titanyl phosphate shell and TiO2 core provided a long-term photochemical stability in aqueous electrolytes with enhanced photocatalytic activities. The titanyl phosphate contributed to the production and stabilization of hydroxyl radicals on the surface of photocatalyst, which facilitated the efficient photooxidation of the organic pollutants. Further, enhancing the photocatalytic hydrogen production was achieved by the titanyl phosphate modified TiO2 (TP-TiO2). Consequently, the conformal titanyl phosphate passivation enhanced photocatalytic activity of TiO2. Comparing to the bare TiO2 nanoparticles, approximately two-fold higher photocatalytic H2 production rate was achieved by the TP-TiO2. Full article
(This article belongs to the Special Issue Nanomaterials for Solar Water Splitting)
Figures

Figure 1

Open AccessArticle Effects of Degraded Optical Fiber Sheaths on Thermal Aging Characteristics of Transformer Oil
Appl. Sci. 2018, 8(8), 1401; https://doi.org/10.3390/app8081401
Received: 15 July 2018 / Revised: 29 July 2018 / Accepted: 16 August 2018 / Published: 19 August 2018
Viewed by 548 | PDF Full-text (3617 KB) | HTML Full-text | XML Full-text
Abstract
With the development of fiber optic sensing technology, optical fiber sensors have been widely used in online monitoring of power transformers. To investigate the influence of aging fiber sheaths on transformer oil, two kinds of special optical fibers with thermoplastic polyester elastomer (TPEE)
[...] Read more.
With the development of fiber optic sensing technology, optical fiber sensors have been widely used in online monitoring of power transformers. To investigate the influence of aging fiber sheaths on transformer oil, two kinds of special optical fibers with thermoplastic polyester elastomer (TPEE) and poly tetra fluoroethylene (PTFE) as sheaths underwent thermally accelerated aging in transformer oil at 130 °C. The volume resistivity, dielectric dissipation factor (DDF), and breakdown voltage of the oil were measured to indicate insulation strength. The water content and acid value of the oil were measured and fitted to predict the aging tends. The thermal aging characteristics of the oil were quantitatively compared and results showed two kinds of optical fibers could exacerbate all the physical and chemical parameters of oil, and the TPEE sheath had a more significant impact on the oil. The reasons contributing to such phenomenon were analyzed using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Both TPEE and PTFE were depolymerized in high-temperature transformer oils, producing water and small molecule hydrocarbon groups. The accumulation of small hydrocarbon groups promoted positive feedback of pyrolysis in the oil. The free hydrogen produced by oil pyrolysis increased the acidity of the oil, which in turn increased the solubility of the water produced by sheath depolymerization. The chain depolymerization of TPEE was more severe than that of PTFE, further exacerbating the deterioration of TPEE-containing oil. Full article
(This article belongs to the Section Materials)
Figures

Figure 1

Open AccessArticle Simulation of Motion Interactions of a 2-DOF Linear Piezoelectric Impact Drive Mechanism with a Single Friction Interface
Appl. Sci. 2018, 8(8), 1400; https://doi.org/10.3390/app8081400
Received: 20 July 2018 / Revised: 16 August 2018 / Accepted: 16 August 2018 / Published: 19 August 2018
Viewed by 512 | PDF Full-text (2575 KB) | HTML Full-text | XML Full-text
Abstract
A two-degrees-of-freedom (2-DOF) linear piezoelectric impact drive mechanism (PIDM) is actuated by two independent piezoelectric actuators (PAs). The coupled motion interactions of a two orthogonal DOF linear PIDM with a single friction interface are introduced and analyzed. A complete dynamic model of the
[...] Read more.
A two-degrees-of-freedom (2-DOF) linear piezoelectric impact drive mechanism (PIDM) is actuated by two independent piezoelectric actuators (PAs). The coupled motion interactions of a two orthogonal DOF linear PIDM with a single friction interface are introduced and analyzed. A complete dynamic model of the 2-DOF PIDM is established with the Karnopp friction model considering the distribution of friction in the x-axis and y-axis. The output displacements of the 2-DOF PIDM and two corresponding independent 1-DOF PIDMs are investigated numerically. When the two input exciting signals of a 2-DOF PIDM have the same driving voltage of 100 V with a duty ratio of 98% at 10 Hz and two 1-DOF PIDMs are driving under the same conditions, the step displacements in the two axes of 2-DOF PIDM are improved compared to the corresponding 1-DOF PIDM. When the two input exciting signals of a 2-DOF PIDM have the same driving voltages of 100 V with a duty ratio of 98% but the driving frequency is 10 Hz in the x-axis and 20 Hz in the y-axis, the results show that the displacement of high frequency achieves a slight decrease and displacement of low frequency shows a large increase compared to the two corresponding 1-DOF PIDMs. Full article
(This article belongs to the Special Issue Piezoelectric Actuators)
Figures

Graphical abstract

Open AccessArticle Calibration Method of Orthogonally Splitting Imaging Pose Sensor Based on General Imaging Model
Appl. Sci. 2018, 8(8), 1399; https://doi.org/10.3390/app8081399
Received: 2 July 2018 / Revised: 26 July 2018 / Accepted: 6 August 2018 / Published: 19 August 2018
Viewed by 510 | PDF Full-text (3850 KB) | HTML Full-text | XML Full-text
Abstract
Orthogonally splitting imaging pose sensor is a new sensor with two orthogonal line array charge coupled devices (CCDs). Owing to its special structure, there are distortion correction and imaging model problems during the calibration procedure. This paper proposes a calibration method based on
[...] Read more.
Orthogonally splitting imaging pose sensor is a new sensor with two orthogonal line array charge coupled devices (CCDs). Owing to its special structure, there are distortion correction and imaging model problems during the calibration procedure. This paper proposes a calibration method based on the general imaging model to solve these problems. The method introduces Plücker Coordinate to describe the mapping relation between the image coordinate system and the world coordinate system. This paper solves the mapping relation with radial basis function interpolation and adaptively selecting control points with Kmeans clustering method to improve the fitting accuracy. This paper determines the appropriate radial basis function and its shape parameter by experiments. And these parameters are used to calibrate the orthogonally splitting imaging pose sensor. According to the calibration result, the root mean square (RMS)of calibration dataset and the RMS of test dataset are 0.048 mm and 0.049 mm. A comparative experiment is conducted between the pinhole imaging model and the general imaging model. Experimental results show that the calibration method based on general imaging model applies to the orthogonally splitting imaging pose sensor. The calibration method requires only one image corresponding to the target in the world coordinates and distortion correction is not required to be taken into account. Compared with the calibration method based on the pinhole imaging model, the calibration procedure based on the general imaging model is easier and accuracy is greater. Full article
(This article belongs to the Special Issue Precision Dimensional Measurements)
Figures

Figure 1

Open AccessArticle Cartilage Differentiation of Bone Marrow-Derived Mesenchymal Stem Cells in Three-Dimensional Silica Nonwoven Fabrics
Appl. Sci. 2018, 8(8), 1398; https://doi.org/10.3390/app8081398
Received: 24 June 2018 / Revised: 9 August 2018 / Accepted: 16 August 2018 / Published: 18 August 2018
Viewed by 567 | PDF Full-text (2015 KB) | HTML Full-text | XML Full-text
Abstract
In cartilage tissue engineering, three-dimensional (3D) scaffolds provide native extracellular matrix (ECM) environments that induce tissue ingrowth and ECM deposition for in vitro and in vivo tissue regeneration. In this report, we investigated 3D silica nonwoven fabrics (Cellbed®) as a scaffold
[...] Read more.
In cartilage tissue engineering, three-dimensional (3D) scaffolds provide native extracellular matrix (ECM) environments that induce tissue ingrowth and ECM deposition for in vitro and in vivo tissue regeneration. In this report, we investigated 3D silica nonwoven fabrics (Cellbed®) as a scaffold for mesenchymal stem cells (MSCs) in cartilage tissue engineering applications. The unique, highly porous microstructure of 3D silica fabrics allows for immediate cell infiltration for tissue repair and orientation of cell–cell interaction. It is expected that the morphological similarity of silica fibers to that of fibrillar ECM contributes to the functionalization of cells. Human bone marrow-derived MSCs were cultured in 3D silica fabrics, and chondrogenic differentiation was induced by culture in chondrogenic differentiation medium. The characteristics of chondrogenic differentiation including cellular growth, ECM deposition of glycosaminoglycan and collagen, and gene expression were evaluated. Because of the highly interconnected network structure, stiffness, and permeability of the 3D silica fabrics, the level of chondrogenesis observed in MSCs seeded within was comparable to that observed in MSCs maintained on atelocollagen gels, which are widely used to study the chondrogenesis of MSCs in vitro and in vivo. These results indicated that 3D silica nonwoven fabrics are a promising scaffold for the regeneration of articular cartilage defects using MSCs, showing the particular importance of high elasticity. Full article
(This article belongs to the Special Issue Biocompatible Materials)
Figures

Graphical abstract

Open AccessArticle Deep Learning for Audio Event Detection and Tagging on Low-Resource Datasets
Appl. Sci. 2018, 8(8), 1397; https://doi.org/10.3390/app8081397
Received: 15 June 2018 / Revised: 11 August 2018 / Accepted: 14 August 2018 / Published: 18 August 2018
Cited by 1 | Viewed by 806 | PDF Full-text (1051 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
In training a deep learning system to perform audio transcription, two practical problems may arise. Firstly, most datasets are weakly labelled, having only a list of events present in each recording without any temporal information for training. Secondly, deep neural networks need a
[...] Read more.
In training a deep learning system to perform audio transcription, two practical problems may arise. Firstly, most datasets are weakly labelled, having only a list of events present in each recording without any temporal information for training. Secondly, deep neural networks need a very large amount of labelled training data to achieve good quality performance, yet in practice it is difficult to collect enough samples for most classes of interest. In this paper, we propose factorising the final task of audio transcription into multiple intermediate tasks in order to improve the training performance when dealing with this kind of low-resource datasets. We evaluate three data-efficient approaches of training a stacked convolutional and recurrent neural network for the intermediate tasks. Our results show that different methods of training have different advantages and disadvantages. Full article
(This article belongs to the Special Issue Computational Acoustic Scene Analysis)
Figures

Graphical abstract

Open AccessArticle Comparative Life Cycle Assessment of End-of-Life Silicon Solar Photovoltaic Modules
Appl. Sci. 2018, 8(8), 1396; https://doi.org/10.3390/app8081396
Received: 26 July 2018 / Revised: 14 August 2018 / Accepted: 14 August 2018 / Published: 18 August 2018
Viewed by 680 | PDF Full-text (4423 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The cumulative global photovoltaic (PV) waste reached 250,000 metric tonnes by the end of 2016 and is expected to increase considerably in the future. Hence, adequate end-of-life (EoL) management for PV modules must be developed. Today, most of the EoL modules go to
[...] Read more.
The cumulative global photovoltaic (PV) waste reached 250,000 metric tonnes by the end of 2016 and is expected to increase considerably in the future. Hence, adequate end-of-life (EoL) management for PV modules must be developed. Today, most of the EoL modules go to landfill, mainly because recycling processes for PV modules are not yet economically feasible and regulation in most countries is not yet well established. Nevertheless, several methods for recycling PV modules are under development. Life cycle assessment (LCA) is a methodology that quantifies the environmental impacts of a process or a product. An attributional LCA was undertaken to compare landfill, incineration, reuse and recycling (mechanical, thermal and chemical routes) of EoL crystalline silicon (c-Si) solar modules, based on a combination of real process data and assumptions. The results show that recovery of materials from solar modules results in lower environmental impacts compared to other EoL scenarios, considering our assumptions. The impacts could be even lower with the adoption of more complex processes that can reclaim more materials. Although recycling processes can achieve good recycling rates and recover almost all materials from solar modules, attention must be paid to the use of toxic substances during the chemical routes of recycling and to the distance to recycling centres due to the impacts of transportation. Full article
(This article belongs to the Special Issue Next Generation Photovoltaic Solar Cells)
Figures

Graphical abstract

Open AccessArticle Evaluation of the Undrained Shear Strength of Organic Soils from a Dilatometer Test Using Artificial Neural Networks
Appl. Sci. 2018, 8(8), 1395; https://doi.org/10.3390/app8081395
Received: 23 July 2018 / Revised: 10 August 2018 / Accepted: 13 August 2018 / Published: 17 August 2018
Viewed by 513 | PDF Full-text (9696 KB) | HTML Full-text | XML Full-text
Abstract
The undrained shear strength of organic soils can be evaluated based on measurements obtained from the dilatometer test using single- and multi-factor empirical correlations presented in the literature. However, the empirical methods may sometimes show relatively high values of maximum relative error. Therefore,
[...] Read more.
The undrained shear strength of organic soils can be evaluated based on measurements obtained from the dilatometer test using single- and multi-factor empirical correlations presented in the literature. However, the empirical methods may sometimes show relatively high values of maximum relative error. Therefore, a method for evaluating the undrained shear strength of organic soils using artificial neural networks based on data obtained from a dilatometer test and organic soil properties is presented in this study. The presented neural network, with an architecture of 5-4-1, predicts the normalized undrained shear strength based on five independent variables: the normalized net value of a corrected first pressure reading (pouo)/σ′v, the normalized net value of a corrected second pressure reading (p1uo)/σ′v, the organic content Iom, the void ratio e, and the stress history indictor (oc or nc). The neural model presented in this study provided a more reliable prediction of the undrained shear strength in comparison to the empirical methods, with a maximum relative error of ±10%. Full article
(This article belongs to the Section Materials)
Figures

Figure 1

Open AccessArticle A New Method for Active Cancellation of Engine Order Noise in a Passenger Car
Appl. Sci. 2018, 8(8), 1394; https://doi.org/10.3390/app8081394
Received: 8 June 2018 / Revised: 3 August 2018 / Accepted: 14 August 2018 / Published: 17 August 2018
Viewed by 534 | PDF Full-text (8769 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a novel active noise cancellation (ANC) method to reduce the engine noise inside the cabin of a car. During the last three decades, many methods have been developed for the active control of a quasi-stationary narrowband sinusoidal signal. However, since
[...] Read more.
This paper presents a novel active noise cancellation (ANC) method to reduce the engine noise inside the cabin of a car. During the last three decades, many methods have been developed for the active control of a quasi-stationary narrowband sinusoidal signal. However, since the interior noise signal is non-stationary with a fast frequency variation when the car accelerates rapidly, these methods cannot stably reduce the interior noise. The proposed method can reduce the interior noise stably even if the speed of the car is changed quickly. The method uses an adaptive filter with an optimal weight vector for the active control of such an engine noise. The method of determining the optimal weight vector of an adaptive filter is demonstrated. In order to validate the advantages of the proposed method, a conventional method and the proposed method are simulated with three synthesized signals. Finally, the proposed method is applied to the cancellation of booming noise in a sport utility vehicle. We demonstrate that the performance of the ANC system with the proposed algorithm is excellent for the attenuation of engine noise inside the cabin of a car. Full article
(This article belongs to the Special Issue Active and Passive Noise Control)
Figures

Figure 1

Open AccessArticle The Accuracy of Predicted Acoustical Parameters in Ancient Open-Air Theatres: A Case Study in Syracusae
Appl. Sci. 2018, 8(8), 1393; https://doi.org/10.3390/app8081393
Received: 20 June 2018 / Revised: 9 August 2018 / Accepted: 10 August 2018 / Published: 17 August 2018
Viewed by 531 | PDF Full-text (2698 KB) | HTML Full-text | XML Full-text
Abstract
Nowadays, ancient open-air theatres are often re-adapted as performance spaces for the additional historical value they can offer to the spectators’ experience. Therefore, there has been an increasing interest in the modelling and simulation of the acoustics of such spaces. These open-air performance
[...] Read more.
Nowadays, ancient open-air theatres are often re-adapted as performance spaces for the additional historical value they can offer to the spectators’ experience. Therefore, there has been an increasing interest in the modelling and simulation of the acoustics of such spaces. These open-air performance facilities pose several methodological challenges to researchers and practitioners when it comes to precisely measure and predict acoustical parameters. Therefore this work investigates the accuracy of predicted acoustical parameters, that is, the Reverberation Time (T20), Clarity (C80) and Sound Strength (G), taking the ancient Syracusae open-air theatre in Italy as a case study. These parameters were derived from both measured and simulated Impulse Responses (IR). The accuracy of the acoustic parameters predicted with two different types of acoustic software, due to the input variability of the absorption and scattering coefficients, was assessed. All simulated and measured parameters were in good agreement, within the range of one “just noticeable difference” (JND), for the tested coefficient combinations. Full article
(This article belongs to the Special Issue Modelling, Simulation and Data Analysis in Acoustical Problems)
Figures

Figure 1

Open AccessArticle Vibration-Based Bearing Fault Detection and Diagnosis via Image Recognition Technique Under Constant and Variable Speed Conditions
Appl. Sci. 2018, 8(8), 1392; https://doi.org/10.3390/app8081392
Received: 16 July 2018 / Revised: 11 August 2018 / Accepted: 13 August 2018 / Published: 17 August 2018
Viewed by 506 | PDF Full-text (10122 KB) | HTML Full-text | XML Full-text
Abstract
This paper addresses the application of an image recognition technique for the detection and diagnosis of ball bearing faults in rotating electrical machines (REMs). The conventional bearing fault detection and diagnosis (BFDD) methods rely on extracting different features from either waveforms or spectra
[...] Read more.
This paper addresses the application of an image recognition technique for the detection and diagnosis of ball bearing faults in rotating electrical machines (REMs). The conventional bearing fault detection and diagnosis (BFDD) methods rely on extracting different features from either waveforms or spectra of vibration signals to detect and diagnose bearing faults. In this paper, a novel vibration-based BFDD via a probability plot (ProbPlot) image recognition technique under constant and variable speed conditions is proposed. The proposed technique is based on the absolute value principal component analysis (AVPCA), namely, ProbPlot via image recognition using the AVPCA (ProbPlot via IR-AVPCA) technique. A comparison of the features (images) obtained: (1) directly in the time domain from the original raw data of the vibration signals; (2) by capturing the Fast Fourier Transformation (FFT) of the vibration signals; or (3) by generating the probability plot (ProbPlot) of the vibration signals as proposed in this paper, is considered. A set of realistic bearing faults (i.e., outer-race fault, inner-race fault, and balls fault) are experimentally considered to evaluate the performance and effectiveness of the proposed ProbPlot via the IR-AVPCA method. Full article
(This article belongs to the Special Issue Fault Detection and Diagnosis in Mechatronics Systems)
Figures

Figure 1

Open AccessArticle Low-Field NMR and MRI to Analyze the Effect of Edible Coating Incorporated with MAP on Qualities of Half-Smooth Tongue Sole (Cynoglossus Semilaevis Günther) Fillets during Refrigerated Storage
Appl. Sci. 2018, 8(8), 1391; https://doi.org/10.3390/app8081391
Received: 30 July 2018 / Revised: 10 August 2018 / Accepted: 15 August 2018 / Published: 17 August 2018
Viewed by 503 | PDF Full-text (1976 KB) | HTML Full-text | XML Full-text
Abstract
Nondestructive and fast measurement and characterization of fish is highly desired during various processing treatments. This research investigated the effectiveness of low field LF-NMR and MRI as fast monitoring techniques to estimate the qualities of half-smooth tongue sole fillets treated with edible coating
[...] Read more.
Nondestructive and fast measurement and characterization of fish is highly desired during various processing treatments. This research investigated the effectiveness of low field LF-NMR and MRI as fast monitoring techniques to estimate the qualities of half-smooth tongue sole fillets treated with edible coating combined with modified atmosphere packaging during refrigeration. T2 relaxation spectra showed three peaks representing bound water (T21), immobile water (T22), and free water (T23), respectively. pT22 accounted for the largest proportion of three types of water, followed by pT23. The weighted MRI provided the internal structure information associated with different samples, indicting the combination of edible coating and MAP (70% CO2 + 30% N2) is the best performance in the maintenance of qualities and freshness of HTS fillets. All results demonstrated that the combination of LF-NMR and MRI as fast and nondestructive methods have great potential to monitor qualities deterioration and predict shelf life in of HTS fillets during refrigerated storage. Full article
(This article belongs to the Special Issue Applications of Low Field Magnetic Resonance)
Figures

Figure 1

Open AccessArticle A Solar–Thermal-Assisted Adiabatic Compressed Air Energy Storage System and Its Efficiency Analysis
Appl. Sci. 2018, 8(8), 1390; https://doi.org/10.3390/app8081390
Received: 14 June 2018 / Revised: 10 August 2018 / Accepted: 14 August 2018 / Published: 17 August 2018
Viewed by 615 | PDF Full-text (3216 KB) | HTML Full-text | XML Full-text
Abstract
Adiabatic compressed air energy storage (A-CAES) is an effective balancing technique for the integration of renewables and peak-shaving due to the large capacity, high efficiency, and low carbon use. Increasing the inlet air temperature of turbine and reducing the compressor power consumption are
[...] Read more.
Adiabatic compressed air energy storage (A-CAES) is an effective balancing technique for the integration of renewables and peak-shaving due to the large capacity, high efficiency, and low carbon use. Increasing the inlet air temperature of turbine and reducing the compressor power consumption are essential to improving the efficiency of A-CAES. This paper proposes a novel solar–thermal-assisted A-CAES system (ST-CAES), which features a higher inhale temperature of the turbine to improve the system efficiency. Solar–thermal energy, as an external thermal source, can alleviate the inadequate temperature of the thermal energy storage (TES), which is constrained by the temperature of the exhaust air of the compressor. Energy and exergy analyses were performed to identify ST-CAES performance, and the influence of key parameters on efficiency were studied. Furthermore, exergy efficiency and the destruction ratio of each component of ST-CAES were investigated. The results demonstrate that electricity storage efficiency, round-trip efficiency, and exergy efficiency can reach 70.2%, 61%, and 50%, respectively. Therefore, the proposed system has promising prospects in cities with abundant solar resources owing to its high efficiency and the ability to jointly supply multiple energy needs. Full article
(This article belongs to the Special Issue Smart Grid and Smart Cities Activities)
Figures

Figure 1

Open AccessArticle Polyadic Cantor Fractal Ultrasonic Lenses: Design and Characterization
Appl. Sci. 2018, 8(8), 1389; https://doi.org/10.3390/app8081389
Received: 5 July 2018 / Revised: 9 August 2018 / Accepted: 15 August 2018 / Published: 17 August 2018
Viewed by 348 | PDF Full-text (1043 KB) | HTML Full-text | XML Full-text
Abstract
Traditional acoustic lenses modulate the ultrasonic beam due to their curved surfaces and the refractive material of which they are made. In this work, a different type of acoustic lens, based on Polyadic Cantor Fractals (PCF), is presented and thoroughly analyzed. These new
[...] Read more.
Traditional acoustic lenses modulate the ultrasonic beam due to their curved surfaces and the refractive material of which they are made. In this work, a different type of acoustic lens, based on Polyadic Cantor Fractals (PCF), is presented and thoroughly analyzed. These new Polyadic Cantor Fractal Lenses (PCFLs) are completely flat and easy to build, and they present interesting modulation capabilities over the acoustic profile. The dependence of the focusing profile on the PCFL design parameters is fully characterized, and it is shown that certain design parameters provide a dynamic control, which is critical in many medical applications such as thermal ablation of tumors. Full article
(This article belongs to the Section Acoustics and Vibrations)
Figures

Figure 1

Open AccessFeature PaperReview Photoelectrochemical Device Designs toward Practical Solar Water Splitting: A Review on the Recent Progress of BiVO4 and BiFeO3 Photoanodes
Appl. Sci. 2018, 8(8), 1388; https://doi.org/10.3390/app8081388
Received: 26 July 2018 / Revised: 11 August 2018 / Accepted: 13 August 2018 / Published: 17 August 2018
Viewed by 874 | PDF Full-text (2632 KB) | HTML Full-text | XML Full-text
Abstract
Solar-driven water splitting technology is considered to be a promising solution for the global energy challenge as it is capable of generating clean chemical fuel from solar energy. Various strategies and catalytic materials have been explored in order to improve the efficiency of
[...] Read more.
Solar-driven water splitting technology is considered to be a promising solution for the global energy challenge as it is capable of generating clean chemical fuel from solar energy. Various strategies and catalytic materials have been explored in order to improve the efficiency of the water splitting reaction. Although significant progress has been made, there are many intriguing fundamental phenomena that need to be understood. Herein, we review recent experimental efforts to demonstrate enhancement strategies for efficient solar water splitting, especially for the light absorption, charge carrier separation, and water oxidation kinetics. We also focus on the state of the art of photoelectrochemical (PEC) device designs such as application of facet engineering and the development of a ferroelectric-coupled PEC device. Based on these experimental achievements, future challenges, and directions in solar water splitting technology will be discussed. Full article
(This article belongs to the Special Issue Nanomaterials for Solar Water Splitting)
Figures

Figure 1

Open AccessArticle A Study on Stability Control of Grid Connected DC Distribution System Based on Second Order Generalized Integrator-Frequency Locked Loop (SOGI-FLL)
Appl. Sci. 2018, 8(8), 1387; https://doi.org/10.3390/app8081387
Received: 21 July 2018 / Revised: 13 August 2018 / Accepted: 13 August 2018 / Published: 16 August 2018
Viewed by 628 | PDF Full-text (15837 KB) | HTML Full-text | XML Full-text
Abstract
This paper studies a second order generalized integrator-frequency locked loop (SOGI-FLL) control scheme applicable for 3-phase alternating current/direct current (AC/DC) pulse width modulation (PWM) converters used in DC distribution systems. The 3-phase AC/DC PWM converter is the most important power conversion system of
[...] Read more.
This paper studies a second order generalized integrator-frequency locked loop (SOGI-FLL) control scheme applicable for 3-phase alternating current/direct current (AC/DC) pulse width modulation (PWM) converters used in DC distribution systems. The 3-phase AC/DC PWM converter is the most important power conversion system of DC distribution, since it can boost 380 Vrms 3-phase line-to-line AC voltage to 700 Vdc DC output with various DC load devices and grid voltages. The direct-quadrature (d-q) transformation, positive sequence voltage extraction, proportional integral (PI) voltage/current control, and phase locked loop (PLL) are necessary to control the 3-phase AC/DC PWM converter. Besides, a digital filter, such as low pass filter and all pass filter, are essential in the conventional synchronous reference frame-phase locked loop (SRF-PLL) method to eliminate the low order harmonics of input. However, they limit the bandwidth of the controller, which directly affects the output voltage and load of 3-phase AC/DC PWM converter when sever voltage fluctuation, such as sag, swell, etc. occurred in the grid. On the other hand, the proposed control method using SOGI-FLL is able to do phase angle detection, positive sequence voltage extraction, and harmonic filtering without additional digital filters, so that more stable and fast transient control is achieved in the DC distribution system. To verify the improvement of the characteristics in the unbalanced voltage and frequency fluctuation of the grid, a simulation and experiment are implemented with 50 kW 3-phase AC/DC PWM converter used in DC distribution. Full article
(This article belongs to the Special Issue HVDC for Grid Services in Electric Power Systems)
Figures

Figure 1

Open AccessArticle Influence of Graphene Nanoplatelet and Silver Nanoparticle on the Rheological Properties of Water-Based Mud
Appl. Sci. 2018, 8(8), 1386; https://doi.org/10.3390/app8081386
Received: 20 July 2018 / Revised: 10 August 2018 / Accepted: 13 August 2018 / Published: 16 August 2018
Viewed by 635 | PDF Full-text (2649 KB) | HTML Full-text | XML Full-text
Abstract
Water-based mud is known as an environmental-friendly drilling fluid system. The formulation of water-based mud is designed to have specific rheological properties under specific oil field conditions. In this study, graphene nanoplatelet and silver nanoparticle (nanosilver) were added to a water-based mud formulation
[...] Read more.
Water-based mud is known as an environmental-friendly drilling fluid system. The formulation of water-based mud is designed to have specific rheological properties under specific oil field conditions. In this study, graphene nanoplatelet and silver nanoparticle (nanosilver) were added to a water-based mud formulation in which they act as drilling mud additives. Rheological properties measurements and filtration tests were conducted for evaluating the influence of the added nanoparticles. The results showed that the graphene nanoplatelet and the nanosilver increased the plastic viscosity (PV) by up to 89.2% and 64.2%, respectively. Meanwhile, both the yield point (YP) and the fluid loss values were reduced. In addition, we believe this is the first result ever report where nanosilver is utilized for enhancing-enhanced water-based mud’s performance. Full article
(This article belongs to the Special Issue Nanotech for Oil and Gas)
Figures

Figure 1

Open AccessArticle Highly Reliable and Efficient Three-Layer Cloud Dispatching Architecture in the Heterogeneous Cloud Computing Environment
Appl. Sci. 2018, 8(8), 1385; https://doi.org/10.3390/app8081385
Received: 21 July 2018 / Revised: 7 August 2018 / Accepted: 13 August 2018 / Published: 16 August 2018
Viewed by 776 | PDF Full-text (2763 KB) | HTML Full-text | XML Full-text
Abstract
Due to the rapid development and popularity of the Internet, cloud computing has become an indispensable application service. However, how to assign various tasks to the appropriate service nodes is an important issue. Based on the reason above, an efficient scheduling algorithm is
[...] Read more.
Due to the rapid development and popularity of the Internet, cloud computing has become an indispensable application service. However, how to assign various tasks to the appropriate service nodes is an important issue. Based on the reason above, an efficient scheduling algorithm is necessary to enhance the performance of the system. Therefore, a Three-Layer Cloud Dispatching (TLCD) architecture is proposed to enhance the performance of task scheduling. In the first layer, the tasks need to be distinguished into different types by their characters. Subsequently, the Cluster Selection Algorithm is proposed to dispatch the tasks to appropriate service clusters in the second layer. Besides this, a new scheduling algorithm is proposed in the third layer to dispatch the task to a suitable server in a server cluster to enhance the scheduling efficiency. Basically, the best task completion time can be obtained in our TLCD architecture. Furthermore, load balancing and reliability can be achieved under a cloud computing network environment. Full article
(This article belongs to the Special Issue Selected Papers from IEEE ICASI 2018)
Figures

Figure 1

Open AccessReview Electricity Generation in LCA of Electric Vehicles: A Review
Appl. Sci. 2018, 8(8), 1384; https://doi.org/10.3390/app8081384
Received: 25 July 2018 / Revised: 10 August 2018 / Accepted: 13 August 2018 / Published: 16 August 2018
Viewed by 828 | PDF Full-text (4513 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Life Cycle assessments (LCAs) on electric mobility are providing a plethora of diverging results. 44 articles, published from 2008 to 2018 have been investigated in this review, in order to find the extent and the reason behind this deviation. The first hurdle can
[...] Read more.
Life Cycle assessments (LCAs) on electric mobility are providing a plethora of diverging results. 44 articles, published from 2008 to 2018 have been investigated in this review, in order to find the extent and the reason behind this deviation. The first hurdle can be found in the goal definition, followed by the modelling choice, as both are generally incomplete and inconsistent. These gaps influence the choices made in the Life Cycle Inventory (LCI) stage, particularly in regards to the selection of the electricity mix. A statistical regression is made with results available in the literature. It emerges that, despite the wide-ranging scopes and the numerous variables present in the assessments, the electricity mix’s carbon intensity can explain 70% of the variability of the results. This encourages a shared framework to drive practitioners in the execution of the assessment and policy makers in the interpretation of the results. Full article
(This article belongs to the Special Issue Plug-in Hybrid Electric Vehicle (PHEV))
Figures

Figure 1

Open AccessArticle A Robust Cover Song Identification System with Two-Level Similarity Fusion and Post-Processing
Appl. Sci. 2018, 8(8), 1383; https://doi.org/10.3390/app8081383
Received: 23 July 2018 / Revised: 13 August 2018 / Accepted: 14 August 2018 / Published: 16 August 2018
Viewed by 639 | PDF Full-text (1359 KB) | HTML Full-text | XML Full-text
Abstract
Similarity measurement plays an important role in various information retrieval tasks. In this paper, a music information retrieval scheme based on two-level similarity fusion and post-processing is proposed. At the similarity fusion level, to take full advantage of the common and complementary properties
[...] Read more.
Similarity measurement plays an important role in various information retrieval tasks. In this paper, a music information retrieval scheme based on two-level similarity fusion and post-processing is proposed. At the similarity fusion level, to take full advantage of the common and complementary properties among different descriptors and different similarity functions, first, the track-by-track similarity graphs generated from the same descriptor but different similarity functions are fused with the similarity network fusion (SNF) technique. Then, the obtained first-level fused similarities based on different descriptors are further fused with the mixture Markov model (MMM) technique. At the post-processing level, diffusion is first performed on the two-level fused similarity graph to utilize the underlying track manifold contained within it. Then, a mutual proximity (MP) algorithm is adopted to refine the diffused similarity scores, which helps to reduce the bad influence caused by the “hubness” phenomenon contained in the scores. The performance of the proposed scheme is tested in the cover song identification (CSI) task on three cover song datasets (Covers80, Covers40, and Second Hand Songs (SHS)). The experimental results demonstrate that the proposed scheme outperforms state-of-the-art CSI schemes based on single similarity or similarity fusion. Full article
(This article belongs to the Special Issue Digital Audio and Image Processing with Focus on Music Research)
Figures

Figure 1

Open AccessArticle Effectiveness of Distributed vs. Concentrated Volt/Var Local Control Strategies in Low-Voltage Grids
Appl. Sci. 2018, 8(8), 1382; https://doi.org/10.3390/app8081382
Received: 28 June 2018 / Revised: 10 August 2018 / Accepted: 13 August 2018 / Published: 16 August 2018
Viewed by 846 | PDF Full-text (13527 KB) | HTML Full-text | XML Full-text
Abstract
This paper introduces a novel local Volt/var control strategy in a low-voltage smart grid. Nowadays, various Volt/var local control strategies built on customer photovoltaic inverters, e.g., cosφ(P) and Q(U), are introduced to mitigate the upper voltage limit
[...] Read more.
This paper introduces a novel local Volt/var control strategy in a low-voltage smart grid. Nowadays, various Volt/var local control strategies built on customer photovoltaic inverters, e.g., cosφ(P) and Q(U), are introduced to mitigate the upper voltage limit violations in feeders with high prosumer share. Nevertheless, although these strategies are further refined by including more local variables, their use is still very limited. In this study, the effects of a new concentrated Volt/var local control strategy in low-voltage grids are investigated. Concentrated var-sinks, e.g., coils-L(U), are set at the end of each violated feeder. The concentrated local control strategy L(U) is compared with the distributed cosφ(P) and Q(U) strategies. Initially, both control strategies are theoretically investigated, followed by simulations in a test feeder. Finally, the expected practical significance of the findings is verified through simulations in a real typical urban and rural grid. Additionally, the impact of the different local control strategies used in low-voltage grids on the behavior of the medium-voltage grid is analyzed. The results show that the concentrated Volt/var control strategy eliminates the violation of upper voltage limit even in longer feeders, where both distributed local strategies fail. In addition, the concentrated L(U) local control causes less reactive power exchange on the distribution transformer level than the distributed cosφ(P) and Q(U) strategies. Therefore, the reactive power exchange with the medium-voltage grid and thus the distribution transformer loading are smaller in the case of concentrated local control strategy. Full article
Figures

Figure 1

Back to Top