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Appl. Sci., Volume 6, Issue 12 (December 2016)

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Open AccessArticle PSO-Based Voltage Control Strategy for Loadability Enhancement in Smart Power Grids
Appl. Sci. 2016, 6(12), 449; https://doi.org/10.3390/app6120449
Received: 25 October 2016 / Revised: 18 November 2016 / Accepted: 14 December 2016 / Published: 20 December 2016
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Abstract
This paper proposes a new voltage control methodology using the particle swarm optimization (PSO) technique for smart grid loadability enhancement. The goal of this paper is to achieve reliable and efficient voltage profile/stability regulation in power grids. This methodology is based on the
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This paper proposes a new voltage control methodology using the particle swarm optimization (PSO) technique for smart grid loadability enhancement. The goal of this paper is to achieve reliable and efficient voltage profile/stability regulation in power grids. This methodology is based on the decouple power flow equations and the worst-case design technique. Specifically, the secondary voltage control (SVC) problem is formulated as an L-infinity norm minimization problem which considers overall load voltage deviations in electrical power systems as an objective model, and the PSO technique is employed to determine a robust control action which aims to improve voltage profile and to enlarge transmission grid loadability by optimal coordinated control of VAR sources. The methodology was successfully tested on several IEEE benchmark systems. Full article
(This article belongs to the Special Issue Selected Papers from the 2016 International Conference on Inventions)
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Open AccessArticle Wavelength Selection for Detection of Slight Bruises on Pears Based on Hyperspectral Imaging
Appl. Sci. 2016, 6(12), 450; https://doi.org/10.3390/app6120450
Received: 5 October 2016 / Revised: 8 December 2016 / Accepted: 15 December 2016 / Published: 19 December 2016
Cited by 1 | PDF Full-text (1826 KB) | HTML Full-text | XML Full-text
Abstract
Hyperspectral imaging technology was employed to detect slight bruises on Korla pears. The spectral data of 60 bruised samples and 60 normal samples were collected by a hyperspectral imaging system. To select the characteristic wavelengths for detection, several chemometrics methods were used on
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Hyperspectral imaging technology was employed to detect slight bruises on Korla pears. The spectral data of 60 bruised samples and 60 normal samples were collected by a hyperspectral imaging system. To select the characteristic wavelengths for detection, several chemometrics methods were used on the raw spectra. Firstly, principal component analysis (PCA) was conducted on the spectra ranging from 420 to 1000 nm of all samples. Considering that the reliability of the first two PCs was more than 90%, five characteristic wavelengths (472, 544, 655, 688 and 967 nm) were selected by the loading plot of PC1 and PC2. Then, each of the wavelength variables was considered as an independent classifier for bruised/normal classification, and all classifiers were evaluated by the receiver operating characteristic (ROC) analysis. Two wavelengths (472 and 967 nm) with the highest values under the curve (0.992 and 0.980) were finally selected for modeling. The classifying model was built by partial least squares discriminant analysis (PLS-DA) and the bruised/normal classification accuracy of the modeling set (45 damaged samples and 45 normal samples) and prediction set (15 damaged samples and 15 normal samples) was 98.9% and 100%, respectively, which is similar to that of the PLS-DA model based on the whole spectral range. The result shows that it is feasible to select characteristic wavelengths for the detection of slight bruises on pears by the methods combining the PCA and ROC analysis. This study can lay a foundation for the development of an online detection system for slight bruise detection on pears. Full article
(This article belongs to the Special Issue Applications of Hyperspectral Imaging for Food and Agriculture)
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Open AccessArticle Multidisciplinary Design Optimization of a Swash-Plate Axial Piston Pump
Appl. Sci. 2016, 6(12), 399; https://doi.org/10.3390/app6120399
Received: 30 October 2016 / Revised: 22 November 2016 / Accepted: 24 November 2016 / Published: 19 December 2016
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Abstract
This work proposes an MDO (multidisciplinary design optimization) procedure for a swash-plate axial piston pump based on co-simulation and integrated optimization. The integrated hydraulic-mechanical model of the pump is built to reflect its actual performance, and a hydraulic-mechanical co-simulation is conducted through data
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This work proposes an MDO (multidisciplinary design optimization) procedure for a swash-plate axial piston pump based on co-simulation and integrated optimization. The integrated hydraulic-mechanical model of the pump is built to reflect its actual performance, and a hydraulic-mechanical co-simulation is conducted through data exchange between different domains. The flow ripple of the pump is optimized by using a MDO procedure. A CFD (Computational Fluid Dynamics) simulation of the pump’s flow field is done, which shows that the hydrodynamic shock of the pump is improved after optimization. To verify the MDO effect, an experimental system is established to test the optimized piston pump. Experimental results show that the simulated and experimental curves are similar. The flow ripple is improved by the MDO procedure. The peak of the pressure curve is lower than before optimization, and the pressure pulsation is reduced by 0.21 MPa, which shows that the pressure pulsation is improved with the decreasing of the flow ripple. Comparing the experimental and simulation results shows that MDO method is effective and feasible in the optimization design of the pump. Full article
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Open AccessArticle Modeling of Integrated Nanoneedle-Microfluidic System for Single Cell Temperature Measurement
Appl. Sci. 2016, 6(12), 339; https://doi.org/10.3390/app6120339
Received: 9 September 2016 / Revised: 22 October 2016 / Accepted: 28 October 2016 / Published: 18 December 2016
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Abstract
In this research, a finite element study on a nanoneedle-microfluidic system for single cell temperature measurement is presented. The nanoneedle design and electrical and mechanical characterization are analyzed, in which tungsten is used as the sensing material. A rectangular shaped sensor with a
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In this research, a finite element study on a nanoneedle-microfluidic system for single cell temperature measurement is presented. The nanoneedle design and electrical and mechanical characterization are analyzed, in which tungsten is used as the sensing material. A rectangular shaped sensor with a gap of 10.8 µm showed to give the same current density distribution within the nanoneedle, and a 90 nm2 cross-sectional area showed to cause minimum damage to the cell. Furthermore, the current showed to have a positive temperature coefficient of resistance (TCR) with an increase in the temperature, and the nanoneedle showed to be able to resist ramp force up to 22.5 μN before failure. Electrical measurement on yeast cell showed that the nanoneedle was independent of the cell conductivity. The nanoneedle proved to be able to measure temperature with a current difference of 50 nA and a resolution of 0.02 °C in 10 ms. A Y-shaped microchannel was proposed and the microchannel cross-sectional area was optimized to be 63 μm2 and a flow rate of 24.6 pL/min allowed successful cell penetration causing minimal damage to the cell. Full article
(This article belongs to the Section Nanotechnology and Applied Nanosciences)
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Open AccessFeature PaperArticle Biodegradable Nanoparticles Made of Amino-Acid-Based Ester Polymers: Preparation, Characterization, and In Vitro Biocompatibility Study
Appl. Sci. 2016, 6(12), 444; https://doi.org/10.3390/app6120444
Received: 20 November 2016 / Revised: 5 December 2016 / Accepted: 8 December 2016 / Published: 17 December 2016
Cited by 1 | PDF Full-text (2630 KB) | HTML Full-text | XML Full-text
Abstract
A systematic study of fabricating nanoparticles (NPs) by cost-effective polymer deposition/solvent displacement (nanoprecipitation) method has been carried out. Five amino acid based biodegradable (AABB) ester polymers (four neutral and one cationic), four organic solvents miscible with water, and eight surfactants were tested for
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A systematic study of fabricating nanoparticles (NPs) by cost-effective polymer deposition/solvent displacement (nanoprecipitation) method has been carried out. Five amino acid based biodegradable (AABB) ester polymers (four neutral and one cationic), four organic solvents miscible with water, and eight surfactants were tested for the fabrication of the goal NPs. Depending on the nature of the AABB polymers, organic solvents and surfactants, as well as on the fabrication conditions, the size (Mean Particle Diameter) of the NPs could be tuned within 42 ÷ 398 nm, the zeta-potential within 12.5 ÷ +28 mV. The stability (resuspendability) of the NPs upon storage (at room temperature and refrigerated) was tested as well. In Vitro biocompatibility study of the NPs was performed with four different stable cell lines: A549, HeLa (human); RAW264.7, Hepa 1-6 (murine). Comparing the NPs parameters, their stability upon storage, and the data of biological examinations the best were found: As the AABB polymer, a poly(ester amide) composed of l-leucine, 1,6-hexanediol and sebacic acid–8L6, as a solvent (organic phase—DMSO), and as a surfactant, Tween 20. Full article
(This article belongs to the Special Issue Biodegradable and Biocompatible Nanoparticles)
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Open AccessArticle Automatic Taxonomic Classification of Fish Based on Their Acoustic Signals
Appl. Sci. 2016, 6(12), 443; https://doi.org/10.3390/app6120443
Received: 26 September 2016 / Revised: 25 November 2016 / Accepted: 13 December 2016 / Published: 17 December 2016
Cited by 6 | PDF Full-text (6251 KB) | HTML Full-text | XML Full-text
Abstract
Fish as well as birds, mammals, insects and other animals are capable of emitting sounds for diverse purposes, which can be recorded through microphone sensors. Although fish vocalizations have been known for a long time, they have been poorly studied and applied in
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Fish as well as birds, mammals, insects and other animals are capable of emitting sounds for diverse purposes, which can be recorded through microphone sensors. Although fish vocalizations have been known for a long time, they have been poorly studied and applied in their taxonomic classification. This work presents a novel approach for automatic remote acoustic identification of fish through their acoustic signals by applying pattern recognition techniques. The sound signals are preprocessed and automatically segmented to extract each call from the background noise. Then, the calls are parameterized using Linear and Mel Frequency Cepstral Coefficients (LFCC and MFCC), Shannon Entropy (SE) and Syllable Length (SL), yielding useful information for the classification phase. In our experiments, 102 different fish species have been successfully identified with three widely used machine learning algorithms: K-Nearest Neighbors (KNN), Random Forest (RF) and Support Vector Machine (SVM). Experimental results show an average classification accuracy of 95.24%, 93.56% and 95.58%, respectively. Full article
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Open AccessArticle A High-Thrust Screw-Type Piezoelectric Ultrasonic Motor with Three-Wavelength Exciting Mode
Appl. Sci. 2016, 6(12), 442; https://doi.org/10.3390/app6120442
Received: 28 October 2016 / Revised: 1 December 2016 / Accepted: 13 December 2016 / Published: 16 December 2016
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Abstract
A high-thrust screw-type piezoelectric ultrasonic motor with a three-wavelength exciting mode is proposed in this paper. The motor mainly includes a stator and a screw output shaft, and the stator is composed of twelve rectangular piezoelectric plates and a hollow metal elastomer with
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A high-thrust screw-type piezoelectric ultrasonic motor with a three-wavelength exciting mode is proposed in this paper. The motor mainly includes a stator and a screw output shaft, and the stator is composed of twelve rectangular piezoelectric plates and a hollow metal elastomer with an internal thread. The stator can be excited to generate the combined micro ultrasonic vibration mode. With this ultrasonic vibration mode, a three-wavelength traveling wave can be synthesized. The three-wavelength traveling wave is used to drive the screw output shaft by means of the frictional force between the stator and the shaft. Rotary-linear motion can be achieved without any additional conversion mechanism. Large thrust output can be easily obtained using a three-wavelength exciting mode. The exciting mode is analyzed in detail. The prototype is designed, simulated, and fabricated. A series of experiments are carried out and the results indicate that the maximum output thrust is 50.8 N at an excitation frequency and peak-to-peak voltage of 28.9 kHz and 120 Vp-p, respectively. The maximum force density is 247.8 N/kg. Full article
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Open AccessArticle Enhancement and Reduction of Nonradiative Decay Process in Organic Light-Emitting Diodes by Gold Nanoparticles
Appl. Sci. 2016, 6(12), 441; https://doi.org/10.3390/app6120441
Received: 19 September 2016 / Revised: 30 November 2016 / Accepted: 8 December 2016 / Published: 16 December 2016
Cited by 2 | PDF Full-text (2003 KB) | HTML Full-text | XML Full-text
Abstract
The influences of gold nanoparticles (GNPs) and the buffer layer on the performance of organic light-emitting diodes are investigated in this study. The GNPs are doped into poly (3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) and the buffer layer is introduced between the hole-transport layer and emitting layer.
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The influences of gold nanoparticles (GNPs) and the buffer layer on the performance of organic light-emitting diodes are investigated in this study. The GNPs are doped into poly (3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) and the buffer layer is introduced between the hole-transport layer and emitting layer. The GNPs are found to have the surface plasmon resonance at a wavelength of 530 nm when the mean particle size of the GNPs is 10 nm. The current efficiency of the device, at a current density of 145 mA/cm2, with GNPs and a buffer layer of 6 nm is about 1.93 times higher than that of the device with prime PEDOT:PSS because the GNPs will generate the surface plasmon resonance effect in the device and the buffer layer can considerably decrease the quenching of the fluorescence. Full article
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Open AccessArticle Design, Development and Implementation of a Smartphone Overdependence Management System for the Self-Control of Smart Devices
Appl. Sci. 2016, 6(12), 440; https://doi.org/10.3390/app6120440
Received: 27 November 2016 / Revised: 9 December 2016 / Accepted: 10 December 2016 / Published: 16 December 2016
Cited by 5 | PDF Full-text (2439 KB) | HTML Full-text | XML Full-text
Abstract
Background: Smartphone overdependence is a type of mental disorder that requires continuous treatment for cure and prevention. A smartphone overdependence management system that is based on scientific evidence is required. This study proposes the design, development and implementation of a smartphone overdependence management
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Background: Smartphone overdependence is a type of mental disorder that requires continuous treatment for cure and prevention. A smartphone overdependence management system that is based on scientific evidence is required. This study proposes the design, development and implementation of a smartphone overdependence management system for self-control of smart devices. Methods: The system architecture of the Smartphone Overdependence Management System (SOMS) primarily consists of four sessions of mental monitoring: (1) Baseline settlement session; (2) Assessment session; (3) Sensing & monitoring session; and (4) Analysis and feedback session. We developed the smartphone-usage-monitoring application (app) and MindsCare personal computer (PC) app to receive and integrate usage data from smartphone users. We analyzed smartphone usage data using the Chi-square Automatic Interaction Detector (CHAID). Based on the baseline settlement results, we designed a feedback service to intervene. We implemented the system using 96 participants for testing and validation. The participants were classified into two groups: the smartphone usage control group (SUC) and the smartphone usage disorder addiction group (SUD). Results: The background smartphone monitoring app of the proposed system successfully monitored the smartphone usage based on the developed algorithm. The usage minutes of the SUD were higher than the usage minutes of the SUC in 11 of the 16 categories developed in our study. Via the MindsCare PC app, the data were successfully integrated and stored, and managers can successfully analyze and diagnose based on the monitored data. Conclusion: The SOMS is a new system that is based on integrated personalized data for evidence-based smartphone overdependence intervention. The SOMS is useful for managing usage data, diagnosing smartphone overdependence, classifying usage patterns and predicting smartphone overdependence. This system contributes to the diagnosis of an abstract mental status, such as smartphone overdependence, based on specific scientific indicators without reliance on consultation. Full article
(This article belongs to the Special Issue Smart Healthcare) Printed Edition available
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Open AccessArticle Icing Forecasting of High Voltage Transmission Line Using Weighted Least Square Support Vector Machine with Fireworks Algorithm for Feature Selection
Appl. Sci. 2016, 6(12), 438; https://doi.org/10.3390/app6120438
Received: 14 September 2016 / Revised: 2 December 2016 / Accepted: 11 December 2016 / Published: 16 December 2016
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Abstract
Accurate forecasting of icing thickness has great significance for ensuring the security and stability of the power grid. In order to improve the forecasting accuracy, this paper proposes an icing forecasting system based on the fireworks algorithm and weighted least square support vector
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Accurate forecasting of icing thickness has great significance for ensuring the security and stability of the power grid. In order to improve the forecasting accuracy, this paper proposes an icing forecasting system based on the fireworks algorithm and weighted least square support vector machine (W-LSSVM). The method of the fireworks algorithm is employed to select the proper input features with the purpose of eliminating redundant influence. In addition, the aim of the W-LSSVM model is to train and test the historical data-set with the selected features. The capability of this proposed icing forecasting model and framework is tested through simulation experiments using real-world icing data from the monitoring center of the key laboratory of anti-ice disaster, Hunan, South China. The results show that the proposed W-LSSVM-FA method has a higher prediction accuracy and it may be a promising alternative for icing thickness forecasting. Full article
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Open AccessFeature PaperReview Poly(α-hydroxy Acids)-Based Cell Microcarriers
Appl. Sci. 2016, 6(12), 436; https://doi.org/10.3390/app6120436
Received: 27 October 2016 / Revised: 10 December 2016 / Accepted: 12 December 2016 / Published: 16 December 2016
Cited by 1 | PDF Full-text (2800 KB) | HTML Full-text | XML Full-text
Abstract
Biodegradable poly(α-hydroxyacids) have gained increasing interest in the biomedical field for their use as cell microcarriers thanks to their biodegradability, biocompatibility, tunable mechanical properties/degradation rates and processability. The synthesis of these poly(α-hydroxyacids) can be finely controlled to yield (co)polymers of desired mechanical properties
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Biodegradable poly(α-hydroxyacids) have gained increasing interest in the biomedical field for their use as cell microcarriers thanks to their biodegradability, biocompatibility, tunable mechanical properties/degradation rates and processability. The synthesis of these poly(α-hydroxyacids) can be finely controlled to yield (co)polymers of desired mechanical properties and degradation rates. On the other hand, by simple emulsion-solvent evaporation techniques, microspheres of controlled size and size distribution can be fabricated. The resulting microspheres can be further surface-modified to enhance cell adhesion and proliferation. As a result of this process, biodegradable microcarriers with advanced functionalities and surface properties that can be directly employed as injectable cell microcarriers are obtained. Full article
(This article belongs to the Special Issue Biodegradable and Biocompatible Nanoparticles)
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Open AccessArticle Development of a Sequential Restoration Strategy Based on the Enhanced Dijkstra Algorithm for Korean Power Systems
Appl. Sci. 2016, 6(12), 435; https://doi.org/10.3390/app6120435
Received: 3 October 2016 / Revised: 2 December 2016 / Accepted: 12 December 2016 / Published: 15 December 2016
Cited by 1 | PDF Full-text (2324 KB) | HTML Full-text | XML Full-text
Abstract
When a blackout occurs, it is important to reduce the time for power system restoration to minimize damage. For fast restoration, it is important to reduce taking time for the selection of generators, transmission lines and transformers. In addition, it is essential that
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When a blackout occurs, it is important to reduce the time for power system restoration to minimize damage. For fast restoration, it is important to reduce taking time for the selection of generators, transmission lines and transformers. In addition, it is essential that a determination of a generator start-up sequence (GSS) be made to restore the power system. In this paper, we propose the optimal selection of black start units through the generator start-up sequence (GSS) to minimize the restoration time using generator characteristic data and the enhanced Dijkstra algorithm. For each restoration step, the sequence selected for the next start unit is recalculated to reflect the system conditions. The proposed method is verified by the empirical Korean power systems. Full article
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Open AccessFeature PaperReview Photonic Packaging: Transforming Silicon Photonic Integrated Circuits into Photonic Devices
Appl. Sci. 2016, 6(12), 426; https://doi.org/10.3390/app6120426
Received: 7 November 2016 / Revised: 1 December 2016 / Accepted: 5 December 2016 / Published: 15 December 2016
Cited by 11 | PDF Full-text (14310 KB) | HTML Full-text | XML Full-text
Abstract
Dedicated multi-project wafer (MPW) runs for photonic integrated circuits (PICs) from Si foundries mean that researchers and small-to-medium enterprises (SMEs) can now afford to design and fabricate Si photonic chips. While these bare Si-PICs are adequate for testing new device and circuit designs
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Dedicated multi-project wafer (MPW) runs for photonic integrated circuits (PICs) from Si foundries mean that researchers and small-to-medium enterprises (SMEs) can now afford to design and fabricate Si photonic chips. While these bare Si-PICs are adequate for testing new device and circuit designs on a probe-station, they cannot be developed into prototype devices, or tested outside of the laboratory, without first packaging them into a durable module. Photonic packaging of PICs is significantly more challenging, and currently orders of magnitude more expensive, than electronic packaging, because it calls for robust micron-level alignment of optical components, precise real-time temperature control, and often a high degree of vertical and horizontal electrical integration. Photonic packaging is perhaps the most significant bottleneck in the development of commercially relevant integrated photonic devices. This article describes how the key optical, electrical, and thermal requirements of Si-PIC packaging can be met, and what further progress is needed before industrial scale-up can be achieved. Full article
(This article belongs to the Special Issue Silicon Photonics Components and Applications)
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Open AccessArticle A Label-Free Aptamer-Based Fluorescent Assay for Cadmium Detection
Appl. Sci. 2016, 6(12), 432; https://doi.org/10.3390/app6120432
Received: 1 November 2016 / Revised: 2 December 2016 / Accepted: 10 December 2016 / Published: 14 December 2016
Cited by 1 | PDF Full-text (1295 KB) | HTML Full-text | XML Full-text
Abstract
Selective detection of ultratrace amounts of cadmium (Cd2+) is extremely important for food safety and environmental monitoring because of its toxicity and widespread use. In this work, we developed a facile, rapid, sensitive, and highly selective method for the detection of
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Selective detection of ultratrace amounts of cadmium (Cd2+) is extremely important for food safety and environmental monitoring because of its toxicity and widespread use. In this work, we developed a facile, rapid, sensitive, and highly selective method for the detection of Cd2+ based on a label-free aptasensor using an unmodified double-stranded deoxyribonucleic acid-specific dye (PicoGreen). The linear range was 0.10–100 µg/mL, and the detection limit (0.038 ng/mL) was lower than the guideline from the World Health Organization for Cd2+ in drinking water (3 ng/mL). The sensor exhibited excellent selectivity towards Cd2+ ions. We tested the aptasensor in application to a series of real water samples spiked with different concentrations of Cd2+. Compared with atomic absorption spectrometry, the results showed good tolerance to the matrix effect. The developed approach shows great potential for on-site and high-throughput analysis in routine monitoring. Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle Green High-Yielding One-Pot Approach to Biginelli Reaction under Catalyst-Free and Solvent-Free Ball Milling Conditions
Appl. Sci. 2016, 6(12), 431; https://doi.org/10.3390/app6120431
Received: 4 November 2016 / Revised: 3 December 2016 / Accepted: 7 December 2016 / Published: 14 December 2016
Cited by 3 | PDF Full-text (384 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A simple, green, and efficient approach was used to synthesize 3,4-dihydropyrimidines derivatives. We showed that the application of the planetary ball milling method with a ball-to-reagent weight ratio of 8 for the Biginelli reaction provides 3,4-dihydropyrimidines derivatives with excellent yields (>98%) in a
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A simple, green, and efficient approach was used to synthesize 3,4-dihydropyrimidines derivatives. We showed that the application of the planetary ball milling method with a ball-to-reagent weight ratio of 8 for the Biginelli reaction provides 3,4-dihydropyrimidines derivatives with excellent yields (>98%) in a short reaction time from the one-pot, three-component condensation of aldehydes, ethyl acetoacetate, and urea (or thiourea). Full article
(This article belongs to the Section Chemistry)
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Open AccessArticle A Psychoacoustic Investigation on the Effect of External Shading Devices on Building Facades
Appl. Sci. 2016, 6(12), 429; https://doi.org/10.3390/app6120429
Received: 10 October 2016 / Revised: 27 November 2016 / Accepted: 5 December 2016 / Published: 14 December 2016
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Abstract
Due to energetic and natural lighting factors, building facades often present external shading devices, but the acoustic properties of such devices have not yet been well studied. This study was carried out using a full-scale model of a portion of a shading device,
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Due to energetic and natural lighting factors, building facades often present external shading devices, but the acoustic properties of such devices have not yet been well studied. This study was carried out using a full-scale model of a portion of a shading device, in a semi-anechoic chamber, using traditional and sound absorbing louvres. The psychoacoustic effects produced by the shading system were evaluated through comparisons between averaged values of loudness, roughness and sharpness levels, as well as sound pressure levels as reference. Results highlighted that the sound absorbing shading device offers good attenuation in terms of loudness, roughness and sound pressure level, with a small reduction in sharpness. The traditional shading system studied does not efficiently reduce the analysed parameters, or even worsens the situation. Several analyses of variance were carried out, one for each situation studied. The sound source position and the louvres’ tilt angle both produce statistically significant effects on almost all of the variations of the parameters studied. The analyses of the partial eta squared factors highlighted that source position and louvre tilt angle affect the variations of the parameters studied to a different degree in respect of the two types of louvres. Full article
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Open AccessArticle Study on the Load Distribution and Dynamic Characteristics of a Thin-Walled Integrated Squirrel-Cage Supporting Roller Bearing
Appl. Sci. 2016, 6(12), 415; https://doi.org/10.3390/app6120415
Received: 7 October 2016 / Revised: 2 December 2016 / Accepted: 3 December 2016 / Published: 14 December 2016
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Abstract
Thin-walled integrated flexible support structures are the major trend in the development of current rolling bearing technology. A thin-walled, integrated, squirrel-cage flexible support roller bearing, quasi-dynamic iterative finite element analysis (FEA) model is established in this paper. The FEA model is used to
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Thin-walled integrated flexible support structures are the major trend in the development of current rolling bearing technology. A thin-walled, integrated, squirrel-cage flexible support roller bearing, quasi-dynamic iterative finite element analysis (FEA) model is established in this paper. The FEA model is used to calculate the structural deformation of the thin-wall rings and support structures; the dynamic characteristics of the bearing are analyzed using the noncircular bearing modified quasi-dynamic model. The influence of the integrated flexible support structure on the internal load distribution and the dynamic characteristics of the roller bearing are analyzed. The results indicate that with the support of a flexible squirrel-cage, the maximum contact load is decreased by 14.2%, the loading region is enlarged by 25%, the cage slide ratio is reduced by 24%, and the fatigue life is increased by more than 50%. In addition, as the ring wall thickness increased, the results increasingly approached those under a rigid assumption. Full article
(This article belongs to the Special Issue Applications of Thin-Walled Structures)
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Open AccessArticle Slip Flow and Heat Transfer of Nanofluids over a Porous Plate Embedded in a Porous Medium with Temperature Dependent Viscosity and Thermal Conductivity
Appl. Sci. 2016, 6(12), 376; https://doi.org/10.3390/app6120376
Received: 20 September 2016 / Revised: 28 October 2016 / Accepted: 3 November 2016 / Published: 14 December 2016
Cited by 6 | PDF Full-text (1187 KB) | HTML Full-text | XML Full-text
Abstract
It is well known that the best way of convective heat transfer is the flow of nanofluids through a porous medium. In this regard, a mathematical model is presented to study the effects of variable viscosity, thermal conductivity and slip conditions on the
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It is well known that the best way of convective heat transfer is the flow of nanofluids through a porous medium. In this regard, a mathematical model is presented to study the effects of variable viscosity, thermal conductivity and slip conditions on the steady flow and heat transfer of nanofluids over a porous plate embedded in a porous medium. The nanofluid viscosity and thermal conductivity are assumed to be linear functions of temperature, and the wall slip conditions are employed in terms of shear stress. The similarity transformation technique is used to reduce the governing system of partial differential equations to a system of nonlinear ordinary differential equations (ODEs). The resulting system of ODEs is then solved numerically using the shooting technique. The numerical values obtained for the velocity and temperature profiles, skin friction coefficient and Nusselt’s number are presented and discussed through graphs and tables. It is shown that the increase in the permeability of the porous medium, the viscosity of the nanofluid and the velocity slip parameter decrease the momentum and thermal boundary layer thickness and eventually increase the rate of heat transfer. Full article
(This article belongs to the Special Issue Recent Developments of Nanofluids) Printed Edition available
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Open AccessReview Characteristics and Applications of Spatiotemporally Focused Femtosecond Laser Pulses
Appl. Sci. 2016, 6(12), 428; https://doi.org/10.3390/app6120428
Received: 12 October 2016 / Revised: 1 December 2016 / Accepted: 7 December 2016 / Published: 13 December 2016
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Abstract
Simultaneous spatial and temporal focusing (SSTF) of femtosecond laser pulses gives rise to strong suppression of nonlinear self-focusing during the propagation of the femtosecond laser beam. In this paper, we begin with an introduction of the principle of SSTF, followed by a review
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Simultaneous spatial and temporal focusing (SSTF) of femtosecond laser pulses gives rise to strong suppression of nonlinear self-focusing during the propagation of the femtosecond laser beam. In this paper, we begin with an introduction of the principle of SSTF, followed by a review of our recent experimental results on the characterization and application of the spatiotemporally focused pulses for femtosecond laser micromachining. Finally, we summarize all of the results and give a future perspective of this technique. Full article
(This article belongs to the Special Issue Ultrashort Optical Pulses)
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Open AccessArticle Dominant Channel Occupancy for Wi-Fi Backscatter Uplink in Industrial Internet of Things
Appl. Sci. 2016, 6(12), 427; https://doi.org/10.3390/app6120427
Received: 9 October 2016 / Revised: 23 November 2016 / Accepted: 8 December 2016 / Published: 13 December 2016
Cited by 1 | PDF Full-text (2467 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents a dominant channel occupancy (DCO) mechanism for the Wi-Fi backscatter uplink in the industrial Internet of things (IIoT). The DCO provides high-priority channel access and reliable burst transmission to the Wi-Fi backscatter devices, thereby enabling the Wi-Fi backscatter tag to
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This paper presents a dominant channel occupancy (DCO) mechanism for the Wi-Fi backscatter uplink in the industrial Internet of things (IIoT). The DCO provides high-priority channel access and reliable burst transmission to the Wi-Fi backscatter devices, thereby enabling the Wi-Fi backscatter tag to deliver its tag information to the Wi-Fi reader without interference from neighboring legacy Wi-Fi devices to guarantee the timeliness and reliability of the IIoT system. For the former, we consider three types of medium access control (MAC) configurations: “carrier sense multiple access with collision avoidance (CSMA/CA) starting with short inter-frame space (SIFS)”, “freezing of the backoff period”, and “reduced CWmin.” In addition, the DCO uses the SIFS between burst packets to guarantee reliable burst transmission. To verify the effectiveness of DCO and determine a proper value for MAC parameters, we conduct experimental simulations under IEEE 802.11n PHY/MAC environments. The simulation results show that the reduced CWmin has the most significant effect on the channel occupancy. The Wi-Fi backscatter devices achieve much higher throughput than the separate cases when two or more configurations are used simultaneously. Moreover, the results exhibit that the use of SIFS between consecutive packets supports reliable burst transmission regardless of the transmission of the legacy Wi-Fi devices in the vicinity. Full article
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Open AccessArticle Maximum Efficiency per Torque Control of Permanent-Magnet Synchronous Machines
Appl. Sci. 2016, 6(12), 425; https://doi.org/10.3390/app6120425
Received: 16 September 2016 / Revised: 21 November 2016 / Accepted: 8 December 2016 / Published: 12 December 2016
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Abstract
High-efficiency permanent-magnet synchronous machine (PMSM) drive systems need not only optimally designed motors but also efficiency-oriented control strategies. However, the existing control strategies only focus on partial loss optimization. This paper proposes a novel analytic loss model of PMSM in either sine-wave pulse-width
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High-efficiency permanent-magnet synchronous machine (PMSM) drive systems need not only optimally designed motors but also efficiency-oriented control strategies. However, the existing control strategies only focus on partial loss optimization. This paper proposes a novel analytic loss model of PMSM in either sine-wave pulse-width modulation (SPWM) or space vector pulse width modulation (SVPWM) which can take into account both the fundamental loss and harmonic loss. The fundamental loss is divided into fundamental copper loss and fundamental iron loss which is estimated by the average flux density in the stator tooth and yoke. In addition, the harmonic loss is obtained from the Bertotti iron loss formula by the harmonic voltages of the three-phase inverter in either SPWM or SVPWM which are calculated by double Fourier integral analysis. Based on the analytic loss model, this paper proposes a maximum efficiency per torque (MEPT) control strategy which can minimize the electromagnetic loss of PMSM in the whole operation range. As the loss model of PMSM is too complicated to obtain the analytical solution of optimal loss, a golden section method is applied to achieve the optimal operation point accurately, which can make PMSM work at maximum efficiency. The optimized results between SPWM and SVPWM show that the MEPT in SVPWM has a better effect on the optimization performance. Both the theory analysis and experiment results show that the MEPT control can significantly improve the efficiency performance of the PMSM in each operation condition with a satisfied dynamic performance. Full article
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Open AccessTechnical Note Nonlinear Vibration Response of a Rectangular Tube with a Flexible End and Non-Rigid Acoustic Boundaries
Appl. Sci. 2016, 6(12), 424; https://doi.org/10.3390/app6120424
Received: 13 September 2016 / Revised: 2 December 2016 / Accepted: 5 December 2016 / Published: 10 December 2016
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Abstract
This paper addresses the analysis for the nonlinear vibration response of a rectangular tube with a flexible end and non-rigid acoustic boundaries. The structural–acoustic modal formulations are developed from the Duffing differential equation and wave equation, which represent the large-amplitude structural vibration of
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This paper addresses the analysis for the nonlinear vibration response of a rectangular tube with a flexible end and non-rigid acoustic boundaries. The structural–acoustic modal formulations are developed from the Duffing differential equation and wave equation, which represent the large-amplitude structural vibration of a flexible panel coupled with a cavity. This problem considers both non-rigid acoustic boundary and structural cubic nonlinearity. The multi-level residue harmonic balance method is employed for solving the nonlinear coupled differential equations developed in the problem. The results obtained from the proposed method and numerical method are generally in good agreement. The effects of excitation magnitude, tube length, and phase shift parameter, etc., are examined. Full article
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Open AccessArticle Reliability Evaluation of a PSC Highway Bridge Based on Resistance Capacity Degradation Due to a Corrosive Environment
Appl. Sci. 2016, 6(12), 423; https://doi.org/10.3390/app6120423
Received: 8 November 2016 / Revised: 6 December 2016 / Accepted: 7 December 2016 / Published: 10 December 2016
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Abstract
This paper presents a method for evaluating the reliability of an in-service highway bridge that considers the resistance capacity loss due to various corrosive environments. To demonstrate the application of the suggested method, a pre-stressed concrete-I (PSC-I) type girder was selected as a
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This paper presents a method for evaluating the reliability of an in-service highway bridge that considers the resistance capacity loss due to various corrosive environments. To demonstrate the application of the suggested method, a pre-stressed concrete-I (PSC-I) type girder was selected as a sample bridge. An analytical procedure was developed to quantitatively evaluate the performance degradation of a PSC-I girder bridge considering the traffic conditions, corrosive environment, and crack damage. The bridge performance was evaluated by considering traffic conditions, including the annual average daily traffic volume, heavy vehicle volume, and corrosive environment (mild, normal, and severe). To calculate the resistance capacity, all variables regarding the materials and sections were considered through probabilistic variances, Monte Carlo simulation, and the statistical characteristics of the resistance. The results showed that the performance degradation is sensitive to the important parameters of the traffic conditions and corrosive environment, which may decrease the structural reliability and lead to bridge failure. Cracks in a PSC-I girder may accelerate the performance degradation and affect the reliability level of the bridge. Therefore, a maintenance plan should be rationally considered depending on the site environment. Full article
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Open AccessArticle Investigation of an Ironless Permanent Magnet Linear Synchronous Motor with Cooling System
Appl. Sci. 2016, 6(12), 422; https://doi.org/10.3390/app6120422
Received: 24 September 2016 / Revised: 22 November 2016 / Accepted: 6 December 2016 / Published: 10 December 2016
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Abstract
In this paper, a novel ironless linear synchronous motor with a cooling system is proposed. Firstly, the topology of this ironless linear synchronous motor with a cooling system is introduced. Flux density in the cooling system is obtained analytically by the separation of
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In this paper, a novel ironless linear synchronous motor with a cooling system is proposed. Firstly, the topology of this ironless linear synchronous motor with a cooling system is introduced. Flux density in the cooling system is obtained analytically by the separation of variables method according to the boundary conditions. The eddy current braking force induced by the cooling system is calculated and validated by finite element method. Then, the influence of the motor parameters on the eddy current braking force is investigated. At last, a prototype is manufactured and some experiments are carried out with the prototype. The experiment results are validated by finite element analyzed results. Full article
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Open AccessArticle Effect of Slot at Blade Root on Compressor Cascade Performance under Different Aerodynamic Parameters
Appl. Sci. 2016, 6(12), 421; https://doi.org/10.3390/app6120421
Received: 9 November 2016 / Revised: 30 November 2016 / Accepted: 6 December 2016 / Published: 10 December 2016
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Abstract
The effects of compressor aerodynamic parameters, such as pitch-chord ratio, aspect ratio, and fillet, on the cascade performance have been studied in this paper. Slot configuration at the root of the blade has been proved to be an efficient passive control method for
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The effects of compressor aerodynamic parameters, such as pitch-chord ratio, aspect ratio, and fillet, on the cascade performance have been studied in this paper. Slot configuration at the root of the blade has been proved to be an efficient passive control method for the corner separation control in compressor cascade. The combined effects of the pitch-chord ratio, aspect ratio, and blade fillet with a slot configuration on the blade, have also been studied. Larger corner separation caused by the high pitch-chord ratio can be eliminated by the slot, which leads to fewer blades with almost the same or even better cascade performance. Various aspect ratios, together with the slot configuration, have been investigated and all of them have a positive effect on the cascade performance. For the blade with the blade fillet, the slot still has a positive effect on the control of the corner separation, while cascade performance with just a slot configuration is better than the slot configuration under the influence of the blade fillet. Full article
(This article belongs to the Special Issue Gas Turbines Propulsion and Power)
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Open AccessArticle Axial Turbine Cascade Correlation
Appl. Sci. 2016, 6(12), 420; https://doi.org/10.3390/app6120420
Received: 10 November 2016 / Revised: 25 November 2016 / Accepted: 6 December 2016 / Published: 10 December 2016
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Abstract
The performance simulation of an axial turbine is achieved in a simple way from the calculation of velocity diagrams. For this purpose, a reliable loss model is needed for the flow through each stationary or rotating axial blade cascade. A loss coefficient assessment
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The performance simulation of an axial turbine is achieved in a simple way from the calculation of velocity diagrams. For this purpose, a reliable loss model is needed for the flow through each stationary or rotating axial blade cascade. A loss coefficient assessment is conducted through the establishment of a correlation between the maximum profile velocity ratio and a circulation parameter, dedicated specifically to turbine cascades. A detailed examination of published wind tunnel cascade tests available in the literature provides enough experimental data to support the proposed correlation. Afterwards, the surface diffusion is quantified and the total pressure loss estimation is obtained from the boundary layer momentum thickness and conservation equations for the downstream flow. Further validation of the proposed loss model is presented from published experimental results in turbine cascades and stages. The simulation methodology is also demonstrated in two single-stage steam turbine units applied to the oil refining industry, in comparison with performance factory tests results. Full article
(This article belongs to the Special Issue Gas Turbines Propulsion and Power)
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Open AccessArticle Improved ADRC for a Maglev Planar Motor with a Concentric Winding Structure
Appl. Sci. 2016, 6(12), 419; https://doi.org/10.3390/app6120419
Received: 9 October 2016 / Revised: 26 November 2016 / Accepted: 6 December 2016 / Published: 10 December 2016
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Abstract
In the semiconductor industry, positioning accuracy and acceleration are critical parameters. To improve the acceleration speed of a motor, this paper proposes the moving-coil maglev planar motor with a concentric winding structure. The coordinate system has been built for the multiple degrees of
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In the semiconductor industry, positioning accuracy and acceleration are critical parameters. To improve the acceleration speed of a motor, this paper proposes the moving-coil maglev planar motor with a concentric winding structure. The coordinate system has been built for the multiple degrees of freedom movement system. The Lorenz force method has been applied to solve its electromagnetic model. The real-time solving of the generalized inverse matrix of factors can realize the decoupling of the winding current. When the maglev height changes, the electromagnetic force and torque decreases exponentially with the increase of the air gap. To decrease the influence on control system performance by the internal model change and the external disturbance, this paper proposes an improved active disturbance rejection control (ADRC) to design the controller. This new controller overcomes the jitter phenomenon due to the turning point for the traditional ADRC, thus it is more suitable for the maglev control system. The comparison between ADRC and the improved ADRC has been conducted, the result of which shows the improved ADRC has greater robustness. Full article
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Open AccessArticle BSNCare+: A Robust IoT-Oriented Healthcare System with Non-Repudiation Transactions
Appl. Sci. 2016, 6(12), 418; https://doi.org/10.3390/app6120418
Received: 30 September 2016 / Revised: 28 November 2016 / Accepted: 6 December 2016 / Published: 9 December 2016
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Abstract
Recently, the rapid advancement in technologies of modern intelligent objects has led to a new network paradigm, called the Internet of Things (IoT), in which every networked and automated object has been connected in a pervasive manner. New types of IoT-based application services
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Recently, the rapid advancement in technologies of modern intelligent objects has led to a new network paradigm, called the Internet of Things (IoT), in which every networked and automated object has been connected in a pervasive manner. New types of IoT-based application services are thus presented. In a healthcare oriented environment, the usage of IoT has brought opportunities for assisting physicians (or nurses) to provide on-demand and real-time body-care services to patients with higher accuracy and better efficiency. However, while IoT-oriented techniques deliver such advantages, they may encounter system security vulnerabilities and patient privacy threats not seen in the past. In this paper, we propose a robust IoT-based healthcare system, called BSNCare+, in which body sensor networks (BSNs) are adopted as the underlying communication architecture. In the proposed healthcare system, we exploit lightweight crypto-primitives to construct a secure communication mechanism that does achieve data confidentiality and entity authentication among intelligent body sensors, the mobile gateway and the backend BSN-Care server. In addition, we evaluate the performance of the proposed healthcare system using the Raspberry PI series platform. The results show the practicability and feasibility of BSNCare+. Full article
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Open AccessArticle Stabilization of Iron (Micro)Particles with Polyhydroxybutyrate for In Situ Remediation Applications
Appl. Sci. 2016, 6(12), 417; https://doi.org/10.3390/app6120417
Received: 4 October 2016 / Revised: 5 December 2016 / Accepted: 6 December 2016 / Published: 9 December 2016
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Abstract
Groundwater is an extremely important resource that may, however, contain a variety of toxic and bioaccumulative contaminants. Traditional “Pump and Treat” technologies for treating contaminated groundwater are no longer time- or cost-effective; therefore, new technologies are needed. In this work, we synthesized core–shell
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Groundwater is an extremely important resource that may, however, contain a variety of toxic and bioaccumulative contaminants. Traditional “Pump and Treat” technologies for treating contaminated groundwater are no longer time- or cost-effective; therefore, new technologies are needed. In this work, we synthesized core–shell materials of micrometric dimensions based on the interaction of iron particles (the core) and fermentable biopolymers such as polyhydroxybutyrate (PHB, the surrounding shell) to be used in permeable reactive barriers for the removal of chlorinated pollutants from contaminated groundwater. The materials were prepared by precipitation techniques that allowed stable preparations to be obtained, whose chemico-physical properties were thoroughly characterized by scanning electron microscopy, porosimetry, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analyses, disc centrifuge analysis, and dynamic light scattering. The properties of the prepared materials are very promising, and may enhance the performance of permeable reactive barriers towards chlorinated compounds. Full article
(This article belongs to the Special Issue Polyhydroxyalkanoates and Their Applications)
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Open AccessArticle Optimized Planning of Power Source Capacity in Microgrid, Considering Combinations of Energy Storage Devices
Appl. Sci. 2016, 6(12), 416; https://doi.org/10.3390/app6120416
Received: 11 October 2016 / Revised: 23 November 2016 / Accepted: 2 December 2016 / Published: 9 December 2016
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Abstract
Since renewable energy resource is universally accepted as a promising method to solve the global energy problem, optimal planning and utilization of various distributed generators (DG) and energy storage (ES) devices deserve special concern. ES devices possess various characteristics in power density, energy
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Since renewable energy resource is universally accepted as a promising method to solve the global energy problem, optimal planning and utilization of various distributed generators (DG) and energy storage (ES) devices deserve special concern. ES devices possess various characteristics in power density, energy density, response speed (switching speed) and lifetime. Besides, as different load types have various requirements on power supply reliability according to their importance, coordinated planning with consideration of reasonable matching between power source and load can efficiently improve power supply reliability and economic efficiency via a customized power supply and compensation strategy. This paper focuses on optimization of power source capacity in microgrid and a coordinated planning strategy is proposed with integrated consideration of characteristics of DG, ES and load. An index named additional compensation ratio (ACR) for balancing economic efficiency and reliability is proposed and considered in the strategy. The objective function which aims to minimize life cycle cost (LCC) is established considering economic efficiency, reliability and environmental conservation. The proposed planning strategy and optimizing model is calculated and verified through case study of an autonomy microgrid. Full article
(This article belongs to the Special Issue Advancing Grid-Connected Renewable Generation Systems)
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