Next Issue
Volume 6, September
Previous Issue
Volume 6, July

Table of Contents

Appl. Sci., Volume 6, Issue 8 (August 2016)

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
Order results
Result details
Select all
Export citation of selected articles as:
Open AccessArticle
Atomic Layer Deposition TiO2 Films and TiO2/SiNx Stacks Applied for Silicon Solar Cells
Appl. Sci. 2016, 6(8), 233; https://doi.org/10.3390/app6080233 - 19 Aug 2016
Cited by 8 | Viewed by 2391
Abstract
Titanium oxide (TiO2) films and TiO2/SiNx stacks have potential in surface passivation, anti-reflection coatings and carrier-selective contact layers for crystalline Si solar cells. A Si wafer, deposited with 8-nm-thick TiO2 film by atomic layer deposition, has a [...] Read more.
Titanium oxide (TiO2) films and TiO2/SiNx stacks have potential in surface passivation, anti-reflection coatings and carrier-selective contact layers for crystalline Si solar cells. A Si wafer, deposited with 8-nm-thick TiO2 film by atomic layer deposition, has a surface recombination velocity as low as 14.93 cm/s at the injection level of 1.0 × 1015 cm−3. However, the performance of silicon surface passivation of the deposited TiO2 film declines as its thickness increases, probably because of the stress effects, phase transformation, atomic hydrogen and thermal stability of amorphous TiO2 films. For the characterization of 66-nm-thick TiO2 film, the results of transmission electron microscopy show that the anatase TiO2 crystallinity forms close to the surface of the Si. Secondary ion mass spectrometry shows the atomic hydrogen at the interface of TiO2 and Si which serves for chemical passivation. The crystal size of anatase TiO2 and the homogeneity of TiO2 film can be deduced by the measurements of Raman spectroscopy and spectroscopic ellipsometry, respectively. For the passivating contacts of solar cells, in addition, a stack composed of 8-nm-thick TiO2 film and a plasma-enhanced chemical-vapor-deposited 72-nm-thick SiNx layer has been investigated. From the results of the measurement of the reflectivity and effective carrier lifetime, TiO2/SiNx stacks on Si wafers perform with low reflectivity and some degree of surface passivation for the Si wafer. Full article
(This article belongs to the Special Issue Silicon Photonics Components and Applications)
Show Figures

Graphical abstract

Open AccessArticle
Laccase Immobilization on Poly(p-Phenylenediamine)/Fe3O4 Nanocomposite for Reactive Blue 19 Dye Removal
Appl. Sci. 2016, 6(8), 232; https://doi.org/10.3390/app6080232 - 17 Aug 2016
Cited by 7 | Viewed by 2399
Abstract
Magnetic poly(p-phenylenediamine) (PpPD) nanocomposite was synthesized via mixing p-phenylenediamine solution and Fe3O4 nanoparticles and used as a carrier for immobilized enzymes. Successful synthesis of PpPD/Fe3O4 nanofiber was confirmed by transmission [...] Read more.
Magnetic poly(p-phenylenediamine) (PpPD) nanocomposite was synthesized via mixing p-phenylenediamine solution and Fe3O4 nanoparticles and used as a carrier for immobilized enzymes. Successful synthesis of PpPD/Fe3O4 nanofiber was confirmed by transmission electron microscopy and Fourier transform infrared spectroscopy. Laccase (Lac) was immobilized on the surface of PpPD/Fe3O4 nanofiber through covalent bonding for reactive blue 19 dye removal. The immobilized Lac-nanofiber conjugates could be recovered from the reaction solution using a magnet. The optimum reaction pH and temperature for the immobilized Lac were 3.5 and 65 °C, respectively. The storage, operational stability, and thermal stability of the immobilized Lac were higher than those of its free counterpart. The dye removal efficiency of immobilized Lac was about 80% in the first 1 h of incubation, while that of free Lac was about 20%. It was found that the unique electronic properties of PpPD might underlie the high dye removal efficiency of immobilized Lac. Over a period of repeated operation, the dye removal efficiency was above 90% during the first two cycles and remained at about 43% after eight cycles. Immobilized Lac on PpPD/Fe3O4 nanofiber showed high stability, easy recovery, reuse capabilities, and a high removal efficiency for reactive blue 19 dye; therefore, it provides an optional tool for dye removal from wastewater. Full article
(This article belongs to the Section Nanotechnology and Applied Nanosciences)
Show Figures

Graphical abstract

Open AccessArticle
Structural Behavior of a Long-Span Partially Earth-Anchored Cable-Stayed Bridge during Installation of a Key Segment by Thermal Prestressing
Appl. Sci. 2016, 6(8), 231; https://doi.org/10.3390/app6080231 - 17 Aug 2016
Cited by 3 | Viewed by 2241
Abstract
This study investigated structural behavior of long-span partially earth-anchored cable-stayed bridges with a main span length of 810 m that use a new key segment closing method based on a thermal prestressing technique. A detailed construction sequence analysis matched with the free cantilever [...] Read more.
This study investigated structural behavior of long-span partially earth-anchored cable-stayed bridges with a main span length of 810 m that use a new key segment closing method based on a thermal prestressing technique. A detailed construction sequence analysis matched with the free cantilever method (FCM) was performed using a three-dimensional finite element (FE) model of a partially earth-anchored cable-stayed bridge. The new method offers an effective way of connecting key segments by avoiding large movements resulting from the removal of the longitudinal restraint owing to the asymmetry of axial forces in the girders near the pylons. The new method develops new member forces through the process of heating the cantilever system before installing the key segment and cooling the system continuously after installing key segments. The resulting forces developed by the thermal process enhance the structural behavior of partially earth-anchored cable-stayed bridges owing to decreased axial forces in the girders. Full article
Show Figures

Graphical abstract

Open AccessArticle
Energy-Harvesting Performances of Two Tandem Piezoelectric Energy Harvesters with Cylinders in Water
Appl. Sci. 2016, 6(8), 230; https://doi.org/10.3390/app6080230 - 17 Aug 2016
Cited by 11 | Viewed by 2368
Abstract
This paper presents a new energy-harvesting system with two identical piezoelectric energy harvesters in a tandem configuration. Each harvester consists of a piezoelectric beam and a circular cylinder. Experiments are performed to investigate the energy-harvesting performances of this system in water. It can [...] Read more.
This paper presents a new energy-harvesting system with two identical piezoelectric energy harvesters in a tandem configuration. Each harvester consists of a piezoelectric beam and a circular cylinder. Experiments are performed to investigate the energy-harvesting performances of this system in water. It can be found that their energy-harvesting performances are all different from that of the single harvester (without an upstream or downstream harvester). The experimental results show that the water speed and the spacing ratio have significant effects on the energy-harvesting performances of the two tandem harvesters. The output power of the upstream harvester first increases, and then decreases with the water speed increasing. The maximum output power of 167.8 μW is achieved at the water speed of 0.306 m/s and the spacing ratio (L/D) of 2.5. Increasing the water speed results in an increase in the energy performance of the downstream harvester. Compared with the single harvester, the performance of the downstream harvester is weakened in the low water speed range, but enhanced in the higher water speed range. Further, the output power of 533 μW is obtained by the downstream harvester at the water speed of 0.412 m/s and the spacing ratio of 1.7, which is 29 times more than that of the single harvester. The results indicate the superiority of the two tandem harvesters in energy-harvesting performance. Full article
Show Figures

Graphical abstract

Open AccessArticle
A New Maximum Power Point Estimator Control Strategy to Maximize Output Power of the Double Stator Permanent Magnet Generator
Appl. Sci. 2016, 6(8), 218; https://doi.org/10.3390/app6080218 - 17 Aug 2016
Cited by 1 | Viewed by 1725
Abstract
A new control estimator to maximize the power generated with a maximum power point estimator is introduced. The power mapping characteristics from the double-stator generator are modeled as a mathematical equation which is used to develop the estimator for maximum power tracking to [...] Read more.
A new control estimator to maximize the power generated with a maximum power point estimator is introduced. The power mapping characteristics from the double-stator generator are modeled as a mathematical equation which is used to develop the estimator for maximum power tracking to maximize the generated power. The proposed estimator automatically traces the instantaneous maximum power at various load conditions. However, to stabilize the output voltage, a boost converter is used from the inverter side. The developed double-stator generator is tested with the new estimator for the maximizing power generation capability under laboratory conditions. The experimental results confirm that with the new estimator, the average power generation capability is increased by 12% and the peak value is increase by 22%. Full article
(This article belongs to the Section Energy)
Show Figures

Figure 1

Open AccessArticle
Chip-Based Cytometry Illuminated by a Blade-Shape Continuous Light for Multispectral Detection
Appl. Sci. 2016, 6(8), 229; https://doi.org/10.3390/app6080229 - 13 Aug 2016
Viewed by 1918
Abstract
A high performance diascopic illumination configuration is presented for the simultaneous detection of cells and particles with different sizes and different fluorescence labels in a microchannel. In the proposed approach, the cells/particles are illuminated by an objective-type dark-field condenser equipped with a low-cost [...] Read more.
A high performance diascopic illumination configuration is presented for the simultaneous detection of cells and particles with different sizes and different fluorescence labels in a microchannel. In the proposed approach, the cells/particles are illuminated by an objective-type dark-field condenser equipped with a low-cost tungsten light source and are then characterized by extracting the side-scatter, absorbance, and fluorescence signals from the spectra obtained by a ultraviolet-visible-near infrared (UV-Vis-NIR) spectrometer. A modified computation model is adopted to improve the capability for discriminating more fluorescence dyes simultaneously. The feasibility of the proposed detection configuration is demonstrated by counting and classifying a mixed sample of green, red, and crimson fluorescent-labeled particles and non-labeled particles with various dimensions. The suitability of the proposed system for real-world cytometry applications is then evaluated by classifying a mixed bio-sample comprising of gastric epithelial (AGS) cells stained with Trypan-blue and Erythrosin-bluish dye, respectively. The results show that the cytometer enables the efficient detection, identification, and classification of mixed bio-samples without the need for spatial filters or delicate optical components. Consequently, the proposed system has significant potential for high-performance micro-flow cytometry applications. Full article
Show Figures

Graphical abstract

Open AccessArticle
Dynamic Similitude Design Method of the Distorted Model on Variable Thickness Cantilever Plates
Appl. Sci. 2016, 6(8), 228; https://doi.org/10.3390/app6080228 - 13 Aug 2016
Cited by 5 | Viewed by 1918
Abstract
In the present study, a new method of predicting the dynamic behavior of a variable thickness (VT) cantilever plate by using a thin plate scaled model is proposed. The thin plate model, defined as the model thin (MT) plate, is designed by using [...] Read more.
In the present study, a new method of predicting the dynamic behavior of a variable thickness (VT) cantilever plate by using a thin plate scaled model is proposed. The thin plate model, defined as the model thin (MT) plate, is designed by using the newly proposed similitude design method. The method is derived based on the transfer matrix of both the stepped thickness (ST) plate that is simplified by the VT plate and the thin plate. The thickness of the MT plate is calculated by introducing the equivalent thickness corresponding to each VT plate’s vibration modals, such that a series of accurate distorted scaling laws are provided to predict each corresponding property. Moreover, an algorithm of designing the MT plate is proposed and a design process is summarized in steps. Finally, an example, where the prototype VT plate is made of 42 CrMo and the MT plate is made of NO. 45 steel, is discussed to validate the proposed design method, showing that the MT plate, which is designed by using the proposed method, can accurately predict the dynamic properties of the prototype VT plate, and showing its significance in engineering practice. Full article
(This article belongs to the Special Issue Applications of Thin-Walled Structures)
Show Figures

Graphical abstract

Open AccessArticle
Optical and Transport Properties of Ni-MoS2
Appl. Sci. 2016, 6(8), 227; https://doi.org/10.3390/app6080227 - 12 Aug 2016
Cited by 4 | Viewed by 1766
Abstract
In this paper, MoS2 and Ni-MoS2 crystal layers were fabricated by the chemical vapor transport method with iodine as the transport agent. Two direct band edge transitions of excitons at 1.9 and 2.1 eV were observed successfully for both MoS2 [...] Read more.
In this paper, MoS2 and Ni-MoS2 crystal layers were fabricated by the chemical vapor transport method with iodine as the transport agent. Two direct band edge transitions of excitons at 1.9 and 2.1 eV were observed successfully for both MoS2 and Ni-MoS2 samples using temperature-dependent optical reflectance (R) measurement. Hall effect measurements were carried out to analyze the transport behavior of carriers in MoS2 and Ni-MoS2, which indicate that the Ni-MoS2 sample is n-type and has a higher resistance and lower mobility than the MoS2 sample has. A photoconductivity spectrum was performed which shows an additional Ni doping level existing at 1.2 eV and a higher photocurrent generating only for Ni-MoS2. The differences between MoS2 and Ni-MoS2 could be attributed to the effect of Ni atoms causing small lattice imperfections to form trap states around 1.2 eV. The temperature-dependent conductivity shows the presence of two shallow levels with activation energies (84 and 6.7 meV in MoS2; 57 and 6.5 meV in Ni-MoS2). Therefore, the Ni doping level leads to high resistance, low mobility and small activation energies. A series of experimental results could provide useful guidance for the fabrication of optoelectronic devices using MoS2 structures. Full article
(This article belongs to the Special Issue Two-Dimensional Transition Metal Dichalcogenides)
Show Figures

Graphical abstract

Open AccessArticle
Analysis and Experimental Research of a Multilayer Linear Piezoelectric Actuator
Appl. Sci. 2016, 6(8), 225; https://doi.org/10.3390/app6080225 - 11 Aug 2016
Cited by 7 | Viewed by 1970
Abstract
To lower the operating voltage and improve the output performance of piezoelectric actuators, a multilayer monolithic ultrasonic linear piezoelectric actuator was analyzed with the method of finite element analysis (FEA), and a prototype was fabricated and experimentally researched in this study. Experimental results [...] Read more.
To lower the operating voltage and improve the output performance of piezoelectric actuators, a multilayer monolithic ultrasonic linear piezoelectric actuator was analyzed with the method of finite element analysis (FEA), and a prototype was fabricated and experimentally researched in this study. Experimental results show that the actuator with a multilayer piezoelectric lead zirconate titanate (PZT) structure (size: 30 × 7.5 × 3 mm3, mass: 5.49 g) can output a pulling force of 5.0 N maximum and a linear velocity up to 270 mm/s at the voltage of 100 Vpp (Vpp means the peak-to-peak value of the voltage volts), showing a relatively good velocity controllability at the same time. The temperature rise characteristic of the actuator at various voltages was studied. The results indicate that: the temperature of this actuator rises rapidly but tends to saturate at some value; applying an offsetting voltage or decreasing the amplitude of the voltage would reduce the heat production. Full article
(This article belongs to the Special Issue Ferroelectric Ceramics)
Show Figures

Graphical abstract

Open AccessArticle
Hydration, Setting and Crack-Resistance Properties of Activated HVFACs at Early Stages
Appl. Sci. 2016, 6(8), 224; https://doi.org/10.3390/app6080224 - 10 Aug 2016
Cited by 1 | Viewed by 1710
Abstract
In order to develop a simple and effective activation method of low calcium fly ash concrete (FAC) and to understand their basic properties, the present paper experimentally investigates the influences of the volume of fly ash (FA), the dosage of the activator (AC) [...] Read more.
In order to develop a simple and effective activation method of low calcium fly ash concrete (FAC) and to understand their basic properties, the present paper experimentally investigates the influences of the volume of fly ash (FA), the dosage of the activator (AC) and the water to binder ratio (w/b) on the hydration, setting times and the crack-resistance properties of activated FACs. Results verify that increasing FA can effectively reduce the hydration heat of the FA-cement system and increase the setting time of FACs, as well as indicate that FA can delay the occurrence of the initial crack and reduce the maximum width and total area of cracks in these concretes through a new quantitative test. The curing time of concrete affects the hydration heat of FA paste with/without AC. When the curing time of FAC increases, the decrease in amplitude of hydration heat reduces gradually. Additionally, it was found that the used ACs can effectively stimulate the activity of FA in Portland cement (PC) systems, which reduces their setting time slightly. However, high dosages of ACs also accelerate the development of early cracks in the FACs, as well. According to the study, the combined activator (10% CaO + 1.5% Na2SO4) was suggested as the most effective way to promote FA-PC concrete for obtaining acceptable properties at early stages. Besides, the existing calculation model for predicting the setting times of FACs was examined and modified to be more suitable to FACs activated by 10% CaO + 1.5% Na2SO4. The proposed model was verified and can evaluate the experimental results well. Full article
Show Figures

Graphical abstract

Open AccessArticle
Evaluation of Reaction Parameters of the Phenol Steam Reforming over Ni/Co on ZrO2 Using the Full Factorial Experimental Design
Appl. Sci. 2016, 6(8), 223; https://doi.org/10.3390/app6080223 - 10 Aug 2016
Cited by 11 | Viewed by 1760
Abstract
Full factorial experimental design with 32 runs was used to investigate the significant and interaction variable of the reaction parameters on phenol steam reforming toward hydrogen production. Effects of selected factors on the phenol conversion (Y1) and hydrogen yield ( [...] Read more.
Full factorial experimental design with 32 runs was used to investigate the significant and interaction variable of the reaction parameters on phenol steam reforming toward hydrogen production. Effects of selected factors on the phenol conversion (Y1) and hydrogen yield (Y2) were evaluated. These factors were as follows: (A) temperature (500 and 800 °C); (B) feed flow rate (0.16–0.46 mL/min); (C) catalyst weight (0.1–0.3 g); (D) Ni-Co ratio (0–1); and (E) phenol concentration in the feed (2–10 wt %). Ni and Co over ZrO2 support for catalytic performance of phenol steam reforming (SRP) was prepared by the impregnation method. The result indicated that all the main independent variables had significant influence on the dependent variable of Y1 and Y2 with a range of 2.7%–96.8% and 21.4%–72.4%, respectively. Additionally, some interaction variables like AE, BE, CE, and DE have also influenced the Y1 and Y2 responses. This design showed that the best initial conditions that produced maximum Y1 and Y2 responses were at 800 °C, 0.16 mL/min feed flow rate, 0.3 g of catalyst, 0 ratio of Ni-Co (Co/ZrO2), and 10 wt % of phenol in the feed, where the phenol conversion was predicted to be 94.98% and the hydrogen yield was predicted to be 67.4%. Within the limits the variables were examined, a regression model which well-fitted the experimental data was proposed. The regression model were reduced to simplify and to get the significant regression coefficient with p-value less than 0.05. Full article
Show Figures

Graphical abstract

Open AccessArticle
Biosynthesis and Biomedical Applications of Gold Nanoparticles Using Eclipta prostrata Leaf Extract
Appl. Sci. 2016, 6(8), 222; https://doi.org/10.3390/app6080222 - 09 Aug 2016
Cited by 9 | Viewed by 2214
Abstract
This study reports the biological synthesis of gold nanoparticles (AuNPs) by the reduction of HAuCl4 by using of Eclipta prostrata leaf extract as the reducing and stabilizing agent. AuNPs were characterized using Ultraviolet–visible (UV-vis) spectroscopy, X-ray diffraction (XRD), Fourier Transform-Infrared (FTIR) spectroscopy, [...] Read more.
This study reports the biological synthesis of gold nanoparticles (AuNPs) by the reduction of HAuCl4 by using of Eclipta prostrata leaf extract as the reducing and stabilizing agent. AuNPs were characterized using Ultraviolet–visible (UV-vis) spectroscopy, X-ray diffraction (XRD), Fourier Transform-Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), High Resolution-Transmission Electron Microscopy (HRTEM), and Energy Dispersive X-ray analysis (EDAX). The UV-visible spectrum of the synthesized AuNPs showed surface plasmon resonance (SPR) around 534 nm. The face-centered cubic (FCC) structure of the AuNPs was confirmed by XRD peaks at 38.10°, 44.13°, 64.43°, and 77.32°, which correspond to (111), (200), (220), and (311) miller indices, respectively, with clear circular spots in the selected area electron diffraction (SAED). FTIR measurements showed the AuNPs having a coating of phenolic compounds, indicating a possible role of biomolecules responsible for capping and efficient stabilization of the AuNPs. The HRTEM images determined the particles are spherical, hexagonal, and triangular in shape, with an average size of 31 ± 1.6 nm. The synthesized AuNPs show good antibacterial, antioxidant, and cytotoxic activity. The outcomes of this study indicate that these nanoparticles could be effectively utilized in pharmaceutical, biotechnological, and biomedical applications. Full article
Show Figures

Graphical abstract

Open AccessArticle
Global Dynamics of Modeling Flocculation of Microorganism
Appl. Sci. 2016, 6(8), 221; https://doi.org/10.3390/app6080221 - 05 Aug 2016
Cited by 8 | Viewed by 1579
Abstract
From a biological perspective, a dynamic model describing the cultivation and flocculation of a microorganism that uses two different kinds of nutrients (carbon source and nitrogen source) is proposed. For the proposed model, there always exists a boundary equilibrium, i.e., R h o [...] Read more.
From a biological perspective, a dynamic model describing the cultivation and flocculation of a microorganism that uses two different kinds of nutrients (carbon source and nitrogen source) is proposed. For the proposed model, there always exists a boundary equilibrium, i.e., R h o d o p s e u d o m o n a s p a l u s t r i s -free equilibrium. Furthermore, under additional conditions, the model also has five positive equilibria at most, i.e., the equilibria for which carbon source, nitrogen source, R h o d o p s e u d o m o n a s p a l u s t r i s and flocculants are coexistent. The phenomena of backward and forward bifurcations are extensively discussed by using center manifold theory. The global stability of the boundary equilibrium of the proposed model is deeply investigated. Moreover, the local stability of the positive equilibrium and the uniform persistence of the proposed model are discussed. Under additional conditions, the global stability of the positive equilibrium is studied. Some control strategies are given by the theoretical analysis. Finally, some numerical simulations are performed to confirm the correctness of the theoretical results. Full article
(This article belongs to the Special Issue Dynamical Models of Biology and Medicine) Printed Edition available
Show Figures

Graphical abstract

Open AccessArticle
Optimal Design and Hybrid Control for the Electro-Hydraulic Dual-Shaking Table System
Appl. Sci. 2016, 6(8), 220; https://doi.org/10.3390/app6080220 - 05 Aug 2016
Cited by 2 | Viewed by 2298
Abstract
This paper is to develop an optimal electro-hydraulic dual-shaking table system with high waveform replication precision. The parameters of hydraulic cylinders, servo valves, hydraulic supply power and gravity balance system are designed and optimized in detail. To improve synchronization and tracking control precision, [...] Read more.
This paper is to develop an optimal electro-hydraulic dual-shaking table system with high waveform replication precision. The parameters of hydraulic cylinders, servo valves, hydraulic supply power and gravity balance system are designed and optimized in detail. To improve synchronization and tracking control precision, a hybrid control strategy is proposed. The cross-coupled control using a novel based on sliding mode control based on adaptive reaching law (ASMC), which can adaptively tune the parameters of sliding mode control (SMC), is proposed to reduce the synchronization error. To improve the tracking performance, the observer-based inverse control scheme combining the feed-forward inverse model controller and disturbance observer is proposed. The system model is identified applying the recursive least squares (RLS) algorithm and then the feed-forward inverse controller is designed based on zero phase error tracking controller (ZPETC) technique. To compensate disturbance and model errors, disturbance observer is used cooperating with the designed inverse controller. The combination of the novel ASMC cross-coupled controller and proposed observer-based inverse controller can improve the control precision noticeably. The dual-shaking table experiment system is built and various experiments are performed. The experimental results indicate that the developed system with the proposed hybrid control strategy is feasible and efficient and can reduce the tracking errors to 25% and synchronization error to 16% compared with traditional control schemes. Full article
Show Figures

Graphical abstract

Open AccessArticle
A Novel 3D Analytical Scattering Model for Air-to-Ground Fading Channels
Appl. Sci. 2016, 6(8), 207; https://doi.org/10.3390/app6080207 - 04 Aug 2016
Cited by 6 | Viewed by 2186
Abstract
A geometry-based three-dimensional (3D) novel stochastic channel model for air-to-ground (A2G) and ground-to-air (G2A) radio propagation environments is proposed. The vicinity of a ground station (GS) is modelled as surrounded by effective scattering points; whereas the elevated air station’s (AS) vicinity is modelled [...] Read more.
A geometry-based three-dimensional (3D) novel stochastic channel model for air-to-ground (A2G) and ground-to-air (G2A) radio propagation environments is proposed. The vicinity of a ground station (GS) is modelled as surrounded by effective scattering points; whereas the elevated air station’s (AS) vicinity is modelled as a scattering-free region. Characterization of the Doppler spectrum, dispersion in the angular domain and second order fading statistics of the A2G/G2A radio communication channels is presented. Closed-form analytical expressions for joint and marginal probability density functions (PDFs) of Doppler shift, power and angle of arrival (AoA) are derived. Next, the paper presents a comprehensive analysis on the characteristics of angular spread on the basis of shape factors (SFs) for A2G/G2A radio propagation environments independently in both the azimuth and elevation planes. The analysis is further extended to second order statistics of the fading channel; where the behaviour of the level crossing rate (LCR), average fade duration (AFD), auto-covariance and coherence distance for the A2G/G2A radio propagation environment is studied. Finally, the impact of physical channel parameters, such as the mobility of AS, the height of AS, the height of GS and the delay of the longest propagation path, on the distribution characteristics of Doppler shift, angular spread and second order statistics is thoroughly studied. Full article
Show Figures

Figure 1

Open AccessArticle
Optimal Control of Drug Therapy in a Hepatitis B Model
Appl. Sci. 2016, 6(8), 219; https://doi.org/10.3390/app6080219 - 03 Aug 2016
Cited by 9 | Viewed by 1970
Abstract
Combination antiviral drug therapy improves the survival rates of patients chronically infected with hepatitis B virus by controlling viral replication and enhancing immune responses. Some of these drugs have side effects that make them unsuitable for long-term administration. To address the trade-off between [...] Read more.
Combination antiviral drug therapy improves the survival rates of patients chronically infected with hepatitis B virus by controlling viral replication and enhancing immune responses. Some of these drugs have side effects that make them unsuitable for long-term administration. To address the trade-off between the positive and negative effects of the combination therapy, we investigated an optimal control problem for a delay differential equation model of immune responses to hepatitis virus B infection. Our optimal control problem investigates the interplay between virological and immunomodulatory effects of therapy, the control of viremia and the administration of the minimal dosage over a short period of time. Our numerical results show that the high drug levels that induce immune modulation rather than suppression of virological factors are essential for the clearance of hepatitis B virus. Full article
(This article belongs to the Special Issue Dynamical Models of Biology and Medicine) Printed Edition available
Show Figures

Figure 1

Open AccessArticle
A Self-Testing Platform with a Foreground Digital Calibration Technique for SAR ADCs
Appl. Sci. 2016, 6(8), 217; https://doi.org/10.3390/app6080217 - 29 Jul 2016
Viewed by 2325
Abstract
This study presents a self-testing platform with a foreground digital calibration technique for successive approximation register (SAR) analog-to-digital converters (ADCs). A high-accuracy digital-to-analog converter (DAC) with digital control is used for the proposed self-testing platform to generate the sinusoidal test signal. This signal [...] Read more.
This study presents a self-testing platform with a foreground digital calibration technique for successive approximation register (SAR) analog-to-digital converters (ADCs). A high-accuracy digital-to-analog converter (DAC) with digital control is used for the proposed self-testing platform to generate the sinusoidal test signal. This signal is then implemented using an Arduino board, and the clock signal is generated to test the ADCs. In addition, fast Fourier transform and recursive discrete Fourier transform (RDFT) processors are adopted for dynamic performance evaluation and calibration of the ADCs. The third harmonic distortion caused by the non-linearity of the track-and-hold circuit, the mismatch of the DAC capacitor array, and the direct current (DC) offset of the comparator can be calculated using the processors to improve the ADC performance. The advantages of the proposed platform include its low cost, high integration, and no need for an extra analogy compensation circuit to deal with calibration. In this work a 12 bit SAR ADC and an RDFT processor are used in the Taiwan Semiconductor Manufacturing Co., Ltd. (TSMC) 0.18 μm standard complementary metal–oxide–semiconductor (CMOS) process with a sampling rate of 18.75 kS/s to validate the proposed method. The measurement results show that the signal-to-noise and distortion ratio is 55.07 dB before calibration and 61.35 dB after calibration. Full article
Show Figures

Graphical abstract

Open AccessArticle
Relationship between Flowability, Entrapped Air Content and Strength of UHPC Mixtures Containing Different Dosage of Steel Fiber
Appl. Sci. 2016, 6(8), 216; https://doi.org/10.3390/app6080216 - 29 Jul 2016
Cited by 11 | Viewed by 1674
Abstract
This study investigated the effects of different fiber contents by volume (0%, 1%, 2%, and 3%) on flowability, entrapped air content, and compressive and flexural strength of ultra high performance concrete (UHPC). Four water-to-binder ratios (0.18, 0.20, 0.22, 0.24) were used and four [...] Read more.
This study investigated the effects of different fiber contents by volume (0%, 1%, 2%, and 3%) on flowability, entrapped air content, and compressive and flexural strength of ultra high performance concrete (UHPC). Four water-to-binder ratios (0.18, 0.20, 0.22, 0.24) were used and four different dosages of superplasticizer were introduced for preparing each water-to-binder ratio mixture. The experimental results reveal that the increased content of fiber decreases the flowability and entrapped air content of fresh UHPC mixtures. The compressive strength of UHPC increased with a greater addition of steel fiber, from 1% to 3%. The flexural strength was increased slightly by the addition of 1% steel fiber and increased remarkably with the addition of 2% and 3% steel fiber. For every water-to-binder ratio mixture, with and without steel fiber, a good linear relationship can be found between compressive strength and entrapped air content. Therefore, it is suggested that lowering the entrapped air provides a significant contribution to increasing compressive strength of UHPC containing higher steel fibers. Full article
Show Figures

Graphical abstract

Open AccessArticle
Mutual Authentication Protocol for Role-Based Access Control Using Mobile RFID
Appl. Sci. 2016, 6(8), 215; https://doi.org/10.3390/app6080215 - 29 Jul 2016
Cited by 9 | Viewed by 1809
Abstract
The Internet has become the main transmission media in modern information systems due to the popularization of information technology and the rapid development of network technology. To use the Internet, we need complete security mechanisms which include requirements such as integrity, security and [...] Read more.
The Internet has become the main transmission media in modern information systems due to the popularization of information technology and the rapid development of network technology. To use the Internet, we need complete security mechanisms which include requirements such as integrity, security and privacy to ensure the legal user can login to a remote server to get the service and resources they need. The radio frequency identification (RFID) is a very convenient technology with the property of non-contact reading. It uses the tag embedded in the object to identify the information quickly. Now, more and more devices are equipped with the RFID reader. Hence, the user can use the RFID reader embedded in the mobile device through a wireless network to read the information on the tag and then use the service which is called Mobile RFID. Compared to traditional RFID, the characteristic of mobility makes the reading more flexible. It can deal with the events in real-time and undertake the process faster and more efficiently. The major security problem of Mobile RFID is privacy, which is also a consideration when constructing a Mobile RFID Mechanism. In this paper, we propose a secure authentication mechanism which uses the authenticated delegating mechanism in Mobile RFID to enable the reader to get the specific role authority through a back-end database server. The reader has to undertake mutual authentication with the back-end database server and the tag. Then, it can protect the information and limit the access times of the reader to achieve privacy. Full article
Show Figures

Graphical abstract

Open AccessArticle
Sharp Switching Characteristics of Single Electron Transistor with Discretized Charge Input
Appl. Sci. 2016, 6(8), 214; https://doi.org/10.3390/app6080214 - 29 Jul 2016
Cited by 1 | Viewed by 1815
Abstract
For the low-power consumption analog and digital circuit applications based on a single-electron transistor, enhancement of its switching performance is required. Our previous works analytically and numerically demonstrated that a discretized charge input device, which comprised a tunnel junction and two capacitors, improved [...] Read more.
For the low-power consumption analog and digital circuit applications based on a single-electron transistor, enhancement of its switching performance is required. Our previous works analytically and numerically demonstrated that a discretized charge input device, which comprised a tunnel junction and two capacitors, improved the gain characteristics of single-electron devices. We report the design and fabrication of an aluminum-based single-electron transistor having the discretized charge input function. Flat-plate and interdigital geometries were employed for adjusting capacitances of grounded and the coupling capacitors. The sample exhibited clear switching on input-output characteristics at the finite temperature. Full article
(This article belongs to the Special Issue Applied Single-Electron Transistors)
Show Figures

Graphical abstract

Open AccessArticle
SEPIM: Secure and Efficient Private Image Matching
Appl. Sci. 2016, 6(8), 213; https://doi.org/10.3390/app6080213 - 29 Jul 2016
Cited by 5 | Viewed by 1552
Abstract
Matching a particular image within extensive datasets has become increasingly pressing in many practical fields. Hence, a number of matching methods have been developed when confidential images are used in image matching between a pair of security agencies, but they are limited by [...] Read more.
Matching a particular image within extensive datasets has become increasingly pressing in many practical fields. Hence, a number of matching methods have been developed when confidential images are used in image matching between a pair of security agencies, but they are limited by either search cost or search precision. In this paper, we propose a privacy-preserving private image matching scheme between two parties where images are confidential, namely secure and efficient private image matching (SEPIM). The descriptor set of the queried party needs to be generated and encrypted properly with the use of a secret key at the queried party side before being transferred to the other party. We present the development and validation of a secure scheme to measure the cosine similarity between two descriptor sets. To hasten the search process, we construct a tree-based index structure by utilizing the k-means clustering algorithm. The method can work without using any image encryption, sharing, and trusted third party. SEPIM is relatively efficient when set against other methods of searching images over plaintexts, and shows a higher search cost of just 14% and reduction in search precision of just 2%. We conducted several empirical analyses on real image collections to demonstrate the performance of our work. Full article
Show Figures

Graphical abstract

Open AccessArticle
Extraction Property of p-tert-Butylsulfonylcalix[4]arene Possessing Irradiation Stability towards Cesium(I) and Strontium(II)
Appl. Sci. 2016, 6(8), 212; https://doi.org/10.3390/app6080212 - 28 Jul 2016
Cited by 3 | Viewed by 1533
Abstract
Solvent extraction behavior of p-tert-butylsulfonylcalix[4]arene (SC4A) towards Cs(I) and Sr(II) from aqueous solutions was studied with respect to the effects of contact time, pH value, SC4A concentration, nitrate concentration and temperature. The extraction of Na(I), K(I), Mg(II), Ca(II), Ba(II), Pb(II), [...] Read more.
Solvent extraction behavior of p-tert-butylsulfonylcalix[4]arene (SC4A) towards Cs(I) and Sr(II) from aqueous solutions was studied with respect to the effects of contact time, pH value, SC4A concentration, nitrate concentration and temperature. The extraction of Na(I), K(I), Mg(II), Ca(II), Ba(II), Pb(II), Cd(II), Zn(II), Co(II), Ni(II), and Ce(III) was also investigated. It was demonstrated that SC4A can sequester both Cs(I) and Sr(II) efficiently from aqueous solutions. According to extraction experiments, Fourier transform infrared and 1H nuclear magnetic resonance analysis of the metal-SC4A complex, authors proposed a possible mechanism involving formation of an adjustable cavity from two SC4A molecules for the complexation of one alkaline earth metal ion, and the size of the adjustable cavity changes depending on the ion within an appropriate range. Irradiation stability of the SC4A was tested, the results indicated that the main structure of SC4A remained unchanged when the temperature was below 400 °C, and SC4A maintains excellent extraction ability for Cs(I) and Sr(II) under an irradiation dose of 1.0 × 104~1.1 × 106 Gy. Full article
Show Figures

Graphical abstract

Open AccessArticle
Assessment of Bacillus pumilus Isolated from Fresh Water Milieu for Bioflocculant Production
Appl. Sci. 2016, 6(8), 211; https://doi.org/10.3390/app6080211 - 27 Jul 2016
Cited by 14 | Viewed by 2043
Abstract
A bioflocculant produced by a Bacillus species was assessed with regards to its physiochemical properties and flocculating efficiency. Identification of the bacteria through 16S rDNA sequencing revealed it to have 99% similarity to Bacillus pumilus strain ZAP 028. The optimum culture conditions for [...] Read more.
A bioflocculant produced by a Bacillus species was assessed with regards to its physiochemical properties and flocculating efficiency. Identification of the bacteria through 16S rDNA sequencing revealed it to have 99% similarity to Bacillus pumilus strain ZAP 028. The optimum culture conditions for bioflocculant production by the bacterial strain were inoculum size of 4% (v/v), maltose as a sole carbon source, multiple nitrogen source (yeast extract, urea and ammonium sulfate) and medium initial pH 7. The bioflocculant was thermostable with high flocculating rate for kaolin suspension at low dosage 0.1 mg/mL over a wide pH range (3–11). Fourier-transform infrared (FTIR) spectroscopy analysis result of the purified bioflocculant showed that hydroxyl, amino and carboxyl groups were the main functional moieties in its molecular structure. The bioflocculant was composed of sugar (75.4%), protein (5.3%) and uronic acid (15.4%). Scanning electron microscopy (SEM) showed a dendritic bioflocculant structure and the energy dispersive X-ray spectroscopy (EDX) analysis revealed that the purified bioflocculant had weight fractions of elements as follows: 22.71% of C, 11.56% of N, 41.60% of O, 0.51% of S and 7.98% of P. The bioflocculant produced had strong flocculating activity and high thermal stability, which affords its utilization in industrial processes. Full article
Show Figures

Graphical abstract

Open AccessArticle
Numerical Descriptions of Hot Flow Behaviors across β Transus for as-Forged Ti–10V–2Fe–3Al Alloy by LHS-SVR and GA-SVR and Improvement in Forming Simulation Accuracy
Appl. Sci. 2016, 6(8), 210; https://doi.org/10.3390/app6080210 - 27 Jul 2016
Cited by 3 | Viewed by 1628
Abstract
Hot compression tests of as-forged Ti–10V–2Fe–3Al alloy in a wide temperature range of 948–1123 K and a strain rate range of 0.001–10 s−1 were conducted by a servo-hydraulic and computer-controlled Gleeble-3500 machine. In order to accurately and effectively model the non-linear flow [...] Read more.
Hot compression tests of as-forged Ti–10V–2Fe–3Al alloy in a wide temperature range of 948–1123 K and a strain rate range of 0.001–10 s−1 were conducted by a servo-hydraulic and computer-controlled Gleeble-3500 machine. In order to accurately and effectively model the non-linear flow behaviors, support vector regression (SVR), as a machine learning method, was combined with Latin hypercube sampling (LHS) and genetic algorithm (GA) to respectively characterize the flow behaviors, namely LHS-SVR and GA-SVR. The significant characters of LHS-SVR and GA-SVR are that they, with identical training parameters, can maintain training accuracy and prediction accuracy at stable levels in different attempts. The study abilities, generalization abilities and modelling efficiencies of the mathematical regression model, artificial neural network (ANN), LHS-SVR and GA-SVR were compared in detail by using standard statistical parameters. After comparisons, the study abilities and generalization abilities of these models were shown as follows in ascending order: the mathematical regression model < ANN < GA-SVR < LHS-SVR. The modeling efficiencies of these models were shown as follows in ascending order: mathematical regression model < ANN < LHS-SVR < GA-SVR. The flow behaviors outside experimental conditions were predicted by the well-trained LHS-SVR, which improves the simulation precision of the load-stroke curve. Full article
Show Figures

Graphical abstract

Open AccessArticle
Classifying Four Carbon Fiber Fabrics via Machine Learning: A Comparative Study Using ANNs and SVM
Appl. Sci. 2016, 6(8), 209; https://doi.org/10.3390/app6080209 - 27 Jul 2016
Cited by 9 | Viewed by 1680
Abstract
Carbon fiber fabrics are important engineering materials. However, it is confusing to classify different carbon fiber fabrics, leading to risks in engineering processes. Here, a classification method for four types of carbon fiber fabrics is proposed using artificial neural networks (ANNs) and support [...] Read more.
Carbon fiber fabrics are important engineering materials. However, it is confusing to classify different carbon fiber fabrics, leading to risks in engineering processes. Here, a classification method for four types of carbon fiber fabrics is proposed using artificial neural networks (ANNs) and support vector machine (SVM) based on 229 experimental data groups. Sample width, breaking strength and breaking tenacity were set as independent variables. Quantified numbers for the four carbon fiber fabrics were set as dependent variables. Results show that a multilayer feed-forward neural network with 21 hidden nodes (MLFN-21) has the best performance for classification, with the lowest root mean square error (RMSE) in the testing set. Full article
(This article belongs to the Special Issue Applied Artificial Neural Network) Printed Edition available
Show Figures

Graphical abstract

Open AccessArticle
A Birefringent-Refraction Transducer for Measuring Angular Displacement Based on Heterodyne Interferometry
Appl. Sci. 2016, 6(8), 208; https://doi.org/10.3390/app6080208 - 25 Jul 2016
Cited by 4 | Viewed by 1663
Abstract
In this paper, an optical angle sensor with a birefringent transducer for measuring angular displacement based on a heterodyne interferometry is proposed. The achievable repeatability and linearity provide sufficient evidence for the practical use. As a result, a resolution of 5.8 × 10 [...] Read more.
In this paper, an optical angle sensor with a birefringent transducer for measuring angular displacement based on a heterodyne interferometry is proposed. The achievable repeatability and linearity provide sufficient evidence for the practical use. As a result, a resolution of 5.8 × 10−6 with a dynamic range of 5° has been achieved by utilizing a KTP (potassium titanyl phosphate) plate immersed in a high refractive index oil with refractive index of 1.7. Full article
(This article belongs to the Section Optics and Lasers)
Show Figures

Figure 1

Open AccessReview
Complex Fluids in Energy Dissipating Systems
Appl. Sci. 2016, 6(8), 206; https://doi.org/10.3390/app6080206 - 25 Jul 2016
Cited by 14 | Viewed by 2098
Abstract
The development of engineered systems for energy dissipation (or absorption) during impacts or vibrations is an increasing need in our society, mainly for human protection applications, but also for ensuring the right performance of different sort of devices, facilities or installations. In the [...] Read more.
The development of engineered systems for energy dissipation (or absorption) during impacts or vibrations is an increasing need in our society, mainly for human protection applications, but also for ensuring the right performance of different sort of devices, facilities or installations. In the last decade, new energy dissipating composites based on the use of certain complex fluids have flourished, due to their non-linear relationship between stress and strain rate depending on the flow/field configuration. This manuscript intends to review the different approaches reported in the literature, analyses the fundamental physics behind them and assess their pros and cons from the perspective of their practical applications. Full article
(This article belongs to the Special Issue Applications of Complex Fluids)
Show Figures

Figure 1

Previous Issue
Next Issue
Back to TopTop