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16 pages, 1109 KiB

Open AccessArticle

A Near-Hover Adaptive Attitude Control Strategy of a Ducted Fan Micro Aerial Vehicle with Actuator Dynamics

by Shouzhao Sheng and Chenwu Sun

Appl. Sci. 2015, 5(4), 666-681; https://doi.org/10.3390/app5040666 - 28 Sep 2015

Cited by 18 | Viewed by 6233

Abstract

The aerodynamic parameters of ducted fan micro aerial vehicles (MAVs) are difficult and expensive to precisely measure and are, therefore, not available in most cases. Furthermore, the actuator dynamics with risks of potentially destabilizing the overall system are important but often neglected consideration [...] Read more.

The aerodynamic parameters of ducted fan micro aerial vehicles (MAVs) are difficult and expensive to precisely measure and are, therefore, not available in most cases. Furthermore, the actuator dynamics with risks of potentially destabilizing the overall system are important but often neglected consideration factors in the control system design of ducted fan MAVs. This paper presents a near-hover adaptive attitude control strategy of a prototype ducted fan MAV with actuator dynamics and without any prior information about the behavior of the MAV. The proposed strategy consists of an online parameter estimation algorithm and an adaptive gain scheduling algorithm, with the former accommodating parametric uncertainties, and the latter approximately eliminating the coupling among axes and guaranteeing the control quality of the MAV. The effectiveness of the proposed strategy is verified numerically and experimentally. Full article

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13 pages, 1443 KiB

Open AccessArticle

Analysis of Losses in Open Circuit Voltage for an 18-μm Silicon Solar Cell

by Lu Wang, Jianshu Han, Anthony Lochtefeld, Andrew Gerger and Allen Barnett

Appl. Sci. 2015, 5(4), 682-694; https://doi.org/10.3390/app5040682 - 29 Sep 2015

Cited by 8 | Viewed by 6599

Abstract

An 18 μm thin crystalline silicon solar cell was demonstrated, and its best open circuit voltage is 642.3 mV. However, this value is far from the cell’s theoretical upper limit in an ideal case. This paper explores the open circuit voltage losses of [...] Read more.

An 18 μm thin crystalline silicon solar cell was demonstrated, and its best open circuit voltage is 642.3 mV. However, this value is far from the cell’s theoretical upper limit in an ideal case. This paper explores the open circuit voltage losses of the thin silicon solar cell, starting from the ideal case, through first principle calculation and experiments. The open circuit voltage losses come from the introduced recombination due to the non-ideal surface passivation and contacts integration on front and rear surfaces, and edge isolation. This paper presents a roadmap of the open circuit voltage reduction from an ideal case of 767.0 mV to the best measured value of 642.3 mV. Full article

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11 pages, 1541 KiB

Open AccessArticle

Characterization of Transition Metal Oxide/Silicon Heterojunctions for Solar Cell Applications

by Luis G. Gerling, Somnath Mahato, Cristobal Voz, Ramon Alcubilla and Joaquim Puigdollers

Appl. Sci. 2015, 5(4), 695-705; https://doi.org/10.3390/app5040695 - 9 Oct 2015

Cited by 103 | Viewed by 12181

Abstract

During the last decade, transition metal oxides have been actively investigated as hole- and electron-selective materials in organic electronics due to their low-cost processing. In this study, four transition metal oxides (V₂O₅, MoO₃, WO₃, and [...] Read more.

During the last decade, transition metal oxides have been actively investigated as hole- and electron-selective materials in organic electronics due to their low-cost processing. In this study, four transition metal oxides (V₂O₅, MoO₃, WO₃, and ReO₃) with high work functions (>5 eV) were thermally evaporated as front p-type contacts in planar n-type crystalline silicon heterojunction solar cells. The concentration of oxygen vacancies in MoO_3−x was found to be dependent on film thickness and redox conditions, as determined by X-ray Photoelectron Spectroscopy. Transfer length method measurements of oxide films deposited on glass yielded high sheet resistances (~10⁹ Ω/sq), although lower values (~10⁴ Ω/sq) were measured for oxides deposited on silicon, indicating the presence of an inversion (hole rich) layer. Of the four oxide/silicon solar cells, ReO₃ was found to be unstable upon air exposure, while V₂O₅ achieved the highest open-circuit voltage (593 mV) and conversion efficiency (12.7%), followed by MoO₃ (581 mV, 12.6%) and WO₃ (570 mV, 11.8%). A short-circuit current gain of ~0.5 mA/cm² was obtained when compared to a reference amorphous silicon contact, as expected from a wider energy bandgap. Overall, these results support the viability of a simplified solar cell design, processed at low temperature and without dopants. Full article

(This article belongs to the Special Issue Selected Papers from the 2nd Spring International School and Workshop of Nanotechnology for the Next Generation High Efficiency Photovoltaics)

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22 pages, 1038 KiB

Open AccessArticle

Trends and Potentials of the Smart Grid Infrastructure: From ICT Sub-System to SDN-Enabled Smart Grid Architecture

by Jaebeom Kim, Fethi Filali and Young-Bae Ko

Appl. Sci. 2015, 5(4), 706-727; https://doi.org/10.3390/app5040706 - 10 Oct 2015

Cited by 39 | Viewed by 11174

Abstract

Context and situational awareness are key features and trends of the smart grid and enable adaptable, flexible and extendable smart grid services. However, the traditional hardware-dependent communication infrastructure is not designed to identify the flow and context of data, and it focuses only [...] Read more.

Context and situational awareness are key features and trends of the smart grid and enable adaptable, flexible and extendable smart grid services. However, the traditional hardware-dependent communication infrastructure is not designed to identify the flow and context of data, and it focuses only on packet forwarding using a pre-defined network configuration profile. Thus, the current network infrastructure may not dynamically adapt the various business models and services of the smart grid system. To solve this problem, software-defined networking (SDN) is being considered in the smart grid, but the design, architecture and system model need to be optimized for the smart grid environment. In this paper, we investigate the state-of-the-art smart grid information subsystem, communication infrastructure and its emerging trends and potentials, called an SDN-enabled smart grid. We present an abstract business model, candidate SDN applications and common architecture of the SDN-enabled smart grid. Further, we compare recent studies into the SDN-enabled smart grid depending on its service functionalities, and we describe further challenges of the SDN-enabled smart grid network infrastructure. Full article

(This article belongs to the Special Issue Smart Grid: Convergence and Interoperability)

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19 pages, 4141 KiB

Open AccessFeature PaperArticle

Phonon Spectrum Engineering in Rolled-up Micro- and Nano-Architectures

by Vladimir M. Fomin and Alexander A. Balandin

Appl. Sci. 2015, 5(4), 728-746; https://doi.org/10.3390/app5040728 - 10 Oct 2015

Cited by 8 | Viewed by 6351

Abstract

We report on a possibility of efficient engineering of the acoustic phonon energy spectrum in multishell tubular structures produced by a novel high-tech method of self-organization of micro- and nano-architectures. The strain-driven roll-up procedure paved the way for novel classes of metamaterials such [...] Read more.

We report on a possibility of efficient engineering of the acoustic phonon energy spectrum in multishell tubular structures produced by a novel high-tech method of self-organization of micro- and nano-architectures. The strain-driven roll-up procedure paved the way for novel classes of metamaterials such as single semiconductor radial micro- and nano-crystals and multi-layer spiral micro- and nano-superlattices. The acoustic phonon dispersion is determined by solving the equations of elastodynamics for InAs and GaAs material systems. It is shown that the number of shells is an important control parameter of the phonon dispersion together with the structure dimensions and acoustic impedance mismatch between the superlattice layers. The obtained results suggest that rolled up nano-architectures are promising for thermoelectric applications owing to a possibility of significant reduction of the thermal conductivity without degradation of the electronic transport. Full article

(This article belongs to the Section Nanotechnology and Applied Nanosciences)

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14 pages, 894 KiB

Open AccessArticle

Effect of the Quality Property of Table Grapes in Cold Chain Logistics-Integrated WSN and AOW

by Xinqing Xiao, Xiang Wang, Xiaoshuan Zhang, Enxiu Chen and Jun Li

Appl. Sci. 2015, 5(4), 747-760; https://doi.org/10.3390/app5040747 - 10 Oct 2015

Cited by 23 | Viewed by 6066

Abstract

Table grapes are very popular for their high nutritional and therapeutic value. The objective of this work was to study the effect of table grapes’ quality property in cold chain logistics for improving the transparency and traceability of table grapes’ cold chain logistics [...] Read more.

Table grapes are very popular for their high nutritional and therapeutic value. The objective of this work was to study the effect of table grapes’ quality property in cold chain logistics for improving the transparency and traceability of table grapes’ cold chain logistics and ensuring the table grapes’ quality and safety. Temperature and relative humidity are monitored by adopting the wireless sensor network (WSN) as the fundamental network infrastructure and adaptive optimal weighted data fusion (AOW) for the adaptive data fusion. The cold chain process, firmness quality and adaptive data fusion of temperature and relative humidity were evaluated in an actual cold chain logistics. The results indicate that the WSN and AOW methods could effectively reflect the real-time temperature and relative humidity information and quality property, improve the transparency and traceability in the cold chain and ensure the preservation of the quality and safety of table grapes. The AOW performance analysis shows that the AOW, whose mean absolute error and mean relative error of the temperature data are 0.06 °C and 8.61% and relative humidity data are 0.12% and 0.23%, respectively, could fuse the sensor data accurately, efficiently and adaptively and meet the actual application requirements. Full article

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9 pages, 718 KiB

Open AccessArticle

MHz Repetion Rate Yb:YAG and Yb:CaF₂ Regenerative Picosecond Laser Amplifiers with a BBO Pockels Cell

by Fedor Bergmann, Mathias Siebold, Markus Loeser, Fabian Röser, Daniel Albach and Ulrich Schramm

Appl. Sci. 2015, 5(4), 761-769; https://doi.org/10.3390/app5040761 - 12 Oct 2015

Cited by 16 | Viewed by 8180

Abstract

We present picosecond Yb:YAG and Yb:CaF2 regenerative laser amplifiers with ultra-high repetition rates in the MHz range. A maximum pulse energy of 40 μJ was obtained at 20 kHz while we achieved around 1 μJ at 1 MHz. We demonstrated a pulse duration [...] Read more.

We present picosecond Yb:YAG and Yb:CaF2 regenerative laser amplifiers with ultra-high repetition rates in the MHz range. A maximum pulse energy of 40 μJ was obtained at 20 kHz while we achieved around 1 μJ at 1 MHz. We demonstrated a pulse duration of 2.1 ps for Yb:YAG and 4.8 ps for Yb:CaF₂ when seeded by a mode-locked Yb:KGW fs-oscillator without pulse stretching or phase compensation. Full article

(This article belongs to the Special Issue Diode-Pumped, Ultra-Short Pulse Lasers)

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17 pages, 2133 KiB

Open AccessArticle

Design of the Secondary Optical Elements for Concentrated Photovoltaic Units with Fresnel Lenses

by Yi-Cheng Chen and Hung-Wei Chiang

Appl. Sci. 2015, 5(4), 770-786; https://doi.org/10.3390/app5040770 - 12 Oct 2015

Cited by 25 | Viewed by 5772

Abstract

The goal of this presented study was to determine the optimum parameters of secondary optical elements (SOEs) for concentrated photovoltaic (CPV) units with flat Fresnel lenses. Three types of SOEs are under consideration in the design process, including kaleidoscope with equal optical path [...] Read more.

The goal of this presented study was to determine the optimum parameters of secondary optical elements (SOEs) for concentrated photovoltaic (CPV) units with flat Fresnel lenses. Three types of SOEs are under consideration in the design process, including kaleidoscope with equal optical path design (KOD), kaleidoscope with flat top surface (KFTS), and open-truncated tetrahedral pyramid with specular walls (SP). The function of using a SOE with a Fresnel lens in a CPV unit is to achieve high optical efficiency, low sensitivity to the sun tracking error, and improved uniformity of irradiance distribution on the solar cell. Ray tracing technique was developed to simulate the optical characteristics of the CPV unit with various design parameters of each type of SOE. Finally, an optimum KOD-type SOE was determined by parametric design process. The resulting optical performance of the CPV unit with the optimum SOE was evaluated in both single-wavelength and broadband simulation of solar spectrum. Full article

(This article belongs to the Special Issue Selected Papers from the International Multi-Conference on Engineering and Technology Innovation 2015 (IMETI2015))

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8 pages, 710 KiB

Open AccessArticle

Kerr-Lens Mode-Locked Femtosecond Yb:GdYSiO₅ Laser Directly Pumped by a Laser Diode

by Jiangfeng Zhu, Ziye Gao, Wenlong Tian, Junli Wang, Zhaohua Wang, Zhiyi Wei, Lihe Zheng, Liangbi Su and Jun Xu

Appl. Sci. 2015, 5(4), 817-824; https://doi.org/10.3390/app5040817 - 15 Oct 2015

Cited by 15 | Viewed by 7211

Abstract

We demonstrate the first Kerr-lens mode-locked operation in a diode-pumped Yb:GdYSiO₅ oscillator. Under a diode pump power of 5 W, 141 fs pulses with an average power of 237 mW were obtained at a repetition rate of 118 MHz. The central wavelength [...] Read more.

We demonstrate the first Kerr-lens mode-locked operation in a diode-pumped Yb:GdYSiO₅ oscillator. Under a diode pump power of 5 W, 141 fs pulses with an average power of 237 mW were obtained at a repetition rate of 118 MHz. The central wavelength was at 1094 nm with a bandwidth of 10.1 nm. Shorter pulses were obtained by adjusting the cavity to operate at a shorter wavelength, resulting in 55 fs pulse duration at the central wavelength of 1054 nm with a bandwidth of 23.5 nm. Full article

(This article belongs to the Special Issue Diode-Pumped, Ultra-Short Pulse Lasers)

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15 pages, 827 KiB

Open AccessArticle

Case-Based FCTF Reasoning System

by Jing Lu, Xiakun Zhang, Peiren Li and Yu Zhu

Appl. Sci. 2015, 5(4), 825-839; https://doi.org/10.3390/app5040825 - 16 Oct 2015

Cited by 5 | Viewed by 5899

Abstract

Case-based reasoning uses old information to infer the answer of new problems. In case-based reasoning, a reasoner firstly records the previous cases, then searches the previous case list that is similar to the current one and uses that to solve the new case. [...] Read more.

Case-based reasoning uses old information to infer the answer of new problems. In case-based reasoning, a reasoner firstly records the previous cases, then searches the previous case list that is similar to the current one and uses that to solve the new case. Case-based reasoning means adapting old solving solutions to new situations. This paper proposes a reasoning system based on the case-based reasoning method. To begin, we show the theoretical structure and algorithm of from coarse to fine (FCTF) reasoning system, and then demonstrate that it is possible to successfully learn and reason new information. Finally, we use our system to predict practical weather conditions based on previous ones and experiments show that the prediction accuracy increases with further learning of the FCTF reasoning system. Full article

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11 pages, 1255 KiB

Open AccessArticle

Chemical Modification of Poly(Vinyl Alcohol) in Water

by Houssein Awada and Claude Daneault

Appl. Sci. 2015, 5(4), 840-850; https://doi.org/10.3390/app5040840 - 20 Oct 2015

Cited by 144 | Viewed by 15481

Abstract

Partial chemical modification of poly(vinyl alcohol) (PVA) was performed through tosylation followed by azidation. Amine functional PVA was also prepared by grafting propargylamine using click chemistry reaction. Through this approach, a tosyl group (a good leaving group), azide group (a group used in [...] Read more.

Partial chemical modification of poly(vinyl alcohol) (PVA) was performed through tosylation followed by azidation. Amine functional PVA was also prepared by grafting propargylamine using click chemistry reaction. Through this approach, a tosyl group (a good leaving group), azide group (a group used in click chemistry) and amine group (a group used for amidation) were attached to PVA polymer chains. The three chemical modifications were performed in water. FTIR and XPS analysis confirmed the chemical modification after each step. Thermogravimetric analysis (TGA) was used to study the thermal stability of the modified PVA. Full article

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30 pages, 5643 KiB

Open AccessArticle

Visual Recognition and Its Application to Robot Arm Control

by Jih-Gau Juang, Yi-Ju Tsai and Yang-Wu Fan

Appl. Sci. 2015, 5(4), 851-880; https://doi.org/10.3390/app5040851 - 20 Oct 2015

Cited by 21 | Viewed by 8833

Abstract

This paper presents an application of optical word recognition and fuzzy control to a smartphone automatic test system. The system consists of a robot arm and two webcams. After the words from the control panel that represent commands are recognized by the robot [...] Read more.

This paper presents an application of optical word recognition and fuzzy control to a smartphone automatic test system. The system consists of a robot arm and two webcams. After the words from the control panel that represent commands are recognized by the robot system, the robot arm performs the corresponding actions to test the smartphone. One of the webcams is utilized to capture commands on the screen of the control panel, the other to recognize the words on the screen of the tested smartphone. The method of image processing is based on the Red-Green-Blue (RGB) and Hue-Saturation-Luminance (HSL) color spaces to reduce the influence of light. Fuzzy theory is used in the robot arm’s position control. The Optical Character Recognition (OCR) technique is applied to the word recognition, and the recognition results are then checked by a dictionary process to increase the recognition accuracy. The camera which is used to recognize the tested smartphone also provides object coordinates to the fuzzy controller, then the robot arm moves to the desired positions and presses the desired buttons. The proposed control scheme allows the robot arm to perform different assigned test functions successfully. Full article

(This article belongs to the Special Issue Selected Papers from the International Multi-Conference on Engineering and Technology Innovation 2015 (IMETI2015))

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13 pages, 1247 KiB

Open AccessArticle

Partial Purification and Characterization of a Thermostable β-Mannanase from Aspergillus foetidus

by Juliana Da Conceição Infante De Marco, Geraldo Pereira de Souza Neto, Carlos Frederico de Souza Castro, Michele Michelin, Maria De Lourdes T. M. Polizeli and Edivaldo Ximenes Ferreira Filho

Appl. Sci. 2015, 5(4), 881-893; https://doi.org/10.3390/app5040881 - 20 Oct 2015

Cited by 11 | Viewed by 5279

Abstract

An extracellular β-mannanase was isolated from samples of crude extract of the mesophilic fungus Aspergillus foetidus grown on soybean husk as a carbon source. The induction profile showed that β-mannanase reached a maximum activity level (2.0 IU/mL) on the 15th day of cultivation. [...] Read more.

An extracellular β-mannanase was isolated from samples of crude extract of the mesophilic fungus Aspergillus foetidus grown on soybean husk as a carbon source. The induction profile showed that β-mannanase reached a maximum activity level (2.0 IU/mL) on the 15th day of cultivation. The enzyme was partially purified by ultrafiltration and gel filtration chromatography procedures and was named Man 58. Sodium dodecyl sulfate-polyacrilamide electrophoresis and zymogram analysis of Man 58 showed two bands of approximately 43 and 45 kDa with β-mannanase activity. Ultrafiltration showed that β-mannanase activity was only detected in the concentrated sample. Man 58 was most active at 60 °C and at pH 4.0. It was thermostable in the temperature range of 40–60 °C for eleven days, and the half-life at 70 °C was ten days. Man 58 showed K_m and V_max values of 3.29 mg/mL and 1.76 IU/mL respectively, with locust bean gum as a substrate. It was mostly activated by FeSO₄ and CoCl₂ and inhibited by MgSO₄, FeCl₃, CuSO₄, MgCl₂, ZnCl₂, ZnSO₄, CaCl₂, CuCl₂, KCl and ethylenediaminetetraacetic acid (EDTA). Phenolic compounds did not inhibit the enzyme. On the other hand, auto-hydrolysis liquor showed an inhibitory effect on Man 58 activity. Full article

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16 pages, 6648 KiB

Open AccessArticle

Sidelobe Reduction in Non-Contiguous OFDM-Based Cognitive Radio Systems Using a Generalized Sidelobe Canceller

by Atif Elahi, Ijaz Mansoor Qureshi, Zafar Ullah Khan and Fawad Zaman

Appl. Sci. 2015, 5(4), 894-909; https://doi.org/10.3390/app5040894 - 21 Oct 2015

Cited by 14 | Viewed by 5980

Abstract

In orthogonal frequency division multiplexing (OFDM), sidelobes of the modulated subcarriers cause high out-of-band (OOB) radiation, resulting in interference to licensed and un-licensed users in a cognitive radio system environment. In this work, we present a novel technique based on a generalized sidelobe [...] Read more.

In orthogonal frequency division multiplexing (OFDM), sidelobes of the modulated subcarriers cause high out-of-band (OOB) radiation, resulting in interference to licensed and un-licensed users in a cognitive radio system environment. In this work, we present a novel technique based on a generalized sidelobe canceller (GSC) for the reduction of sidelobes. The upper branch of the GSC consists of a weight vector designed by multiple constraints to preserve the desired portion of the input signal. The lower branch has a blocking matrix that blocks the desired portion and preserves the undesired portion (the sidelobes) of the input signal, followed by an adaptive weight vector. The adaptive weight vector adjusts the amplitudes of the undesired portion (the sidelobes) so that when the signal from the lower branch is subtracted from the signal from the upper branch, it results in cancellation of the sidelobes of the input signal. The effectiveness and strength of the proposed technique are verified through extensive simulations. The proposed technique produces competitive results in terms of sidelobe reduction as compared to existing techniques. Full article

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16 pages, 3999 KiB

Open AccessArticle

Double Properties of Novel Acylhydrazone Nanomaterials Based on a Conjugated System: Anion Binding Ability and Antibacterial Activity

by Xuefang Shang, Wanli Li, Yaqian Feng, Xin Li and Xiufang Xu

Appl. Sci. 2015, 5(4), 910-925; https://doi.org/10.3390/app5040910 - 21 Oct 2015

Cited by 1 | Viewed by 4678

Abstract

A series of new compounds (1–12) containing 1,5-diaza-fluorenone, 1,10-phenanthroline-5,6-dione, ferrocene-1,1ʹ-dione, anthracene-9-carbaldehyde have been synthesized and optimized. The nanomaterials were also developed successfully. The binding properties were evaluated for biologically important anions (F⁻, Cl⁻, Br⁻ [...] Read more.

A series of new compounds (1–12) containing 1,5-diaza-fluorenone, 1,10-phenanthroline-5,6-dione, ferrocene-1,1ʹ-dione, anthracene-9-carbaldehyde have been synthesized and optimized. The nanomaterials were also developed successfully. The binding properties were evaluated for biologically important anions (F⁻, Cl⁻, Br⁻, I⁻, AcO⁻, and H₂PO₄⁻) by theoretical investigation, UV-vis, and fluorescence experiments, and compound 6 displayed the strongest binding ability for AcO⁻ ion among the synthesized compounds. Theoretical investigation analysis revealed that the intramolecular hydrogen bond existed in the structure of compound 6 and the roles of molecular frontier orbitals in molecular interplay. In addition, compound 6 showed wide antibacterial activity for colon bacillus, typhoid bacillus, and Pseudomonas aeruginosa, and inferior activity for hay bacillus and Staphylococcus aureus. This series of acylhydrazone nanomaterials showed double properties, anion binding ability, and antibacterial activity. Full article

(This article belongs to the Section Nanotechnology and Applied Nanosciences)

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16 pages, 2482 KiB

Open AccessArticle

Study of Three-Dimensional Image Brightness Loss in Stereoscopy

by Hsing-Cheng Yu, Xie-Hong Tsai, An-Chun Luo, Ming Wu and Sei-Wang Chen

Appl. Sci. 2015, 5(4), 926-941; https://doi.org/10.3390/app5040926 - 21 Oct 2015

Cited by 2 | Viewed by 5576

Abstract

When viewing three-dimensional (3D) images, whether in cinemas or on stereoscopic televisions, viewers experience the same problem of image brightness loss. This study aims to investigate image brightness loss in 3D displays, with the primary aim being to quantify the image brightness degradation [...] Read more.

When viewing three-dimensional (3D) images, whether in cinemas or on stereoscopic televisions, viewers experience the same problem of image brightness loss. This study aims to investigate image brightness loss in 3D displays, with the primary aim being to quantify the image brightness degradation in the 3D mode. A further aim is to determine the image brightness relationship to the corresponding two-dimensional (2D) images in order to adjust the 3D-image brightness values. In addition, the photographic principle is used in this study to measure metering values by capturing 2D and 3D images on television screens. By analyzing these images with statistical product and service solutions (SPSS) software, the image brightness values can be estimated using the statistical regression model, which can also indicate the impact of various environmental factors or hardware on the image brightness. In analysis of the experimental results, comparison of the image brightness between 2D and 3D images indicates 60.8% degradation in the 3D image brightness amplitude. The experimental values, from 52.4% to 69.2%, are within the 95% confidence interval Full article

(This article belongs to the Special Issue Selected Papers from the International Multi-Conference on Engineering and Technology Innovation 2015 (IMETI2015))

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13 pages, 2374 KiB

Open AccessArticle

Fabrication and Simulation of Self-Focusing Field Emission X-ray Tubes

by Kevin Cheng, Yi-Ping Chou, Meng-Jey Youh, Yih-Ming Liu, Ming-Der Ger, Kung-Hsu Hou and Nen-Wen Pu

Appl. Sci. 2015, 5(4), 942-954; https://doi.org/10.3390/app5040942 - 26 Oct 2015

Cited by 4 | Viewed by 7311

Abstract

A self-focusing field emission (FE) X-ray tube with a large-area cathode design was simulated and fabricated. The designed X-ray tube had a cylindrically symmetric geometry; the diameter of the cathode and the anode was 15 mm, and the cathode-anode distance was 20 mm. [...] Read more.

A self-focusing field emission (FE) X-ray tube with a large-area cathode design was simulated and fabricated. The designed X-ray tube had a cylindrically symmetric geometry; the diameter of the cathode and the anode was 15 mm, and the cathode-anode distance was 20 mm. Owing to the unique cup-shaped design of the cathode, the electron beam emitted from the large-area cathode was focused onto the anode without using magnetic lenses or extra biased electrodes. Carbon nanocoils, which were grown on the bottom of the circular cup-shaped cathode, were used as electron emitters because of their excellent FE properties. A simulation of the electron trajectories for various cup heights revealed that the optimal focal spot size (0.1 mm) was obtained at a cup height of 5 mm when a voltage of 50 kV was applied. To verify this result, an X-ray tube was fabricated and tested. An X-ray photograph of the tested tooth and electric circuits showed good resolution and X-ray intensity. The large cathode area effectively reduces the current density and thereby improves the lifetime of the cathode. Full article

(This article belongs to the Special Issue Selected Papers from the International Multi-Conference on Engineering and Technology Innovation 2015 (IMETI2015))

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18 pages, 8353 KiB

Open AccessArticle

Experimental and Theoretical Studies of the Vibrational and Electronic Properties of (2E)-2-[3-(1H-imidazol-1-yl)-1-phenyl-propylidene]-N-phenylhydrazinecarboxamide: An Anticonvulsant Agent

by Munusamy Govindarajan, Ali S. Abdelhameed, Abdulaziz A. Al-Saadi and Mohamed I. Attia

Appl. Sci. 2015, 5(4), 955-972; https://doi.org/10.3390/app5040955 - 29 Oct 2015

Cited by 10 | Viewed by 5344

Abstract

In the current investigation, the molecular structure of the anticonvulsant agent (2E)-2-[3-(1H-imidazol-1-yl)-1-phenylpropylidene]-N-phenylhydrazinecarboxamide ((2E)-HIPC) was theoretically modelled using ab initio Hartree-Fock (HF) and density functional theory (DFT/B3LYP) calculations. The Fourier transform (FT) infrared and FT-Raman spectra [...] Read more.

In the current investigation, the molecular structure of the anticonvulsant agent (2E)-2-[3-(1H-imidazol-1-yl)-1-phenylpropylidene]-N-phenylhydrazinecarboxamide ((2E)-HIPC) was theoretically modelled using ab initio Hartree-Fock (HF) and density functional theory (DFT/B3LYP) calculations. The Fourier transform (FT) infrared and FT-Raman spectra of (2E)-HIPC were also recorded, and the observed bands were assigned to the vibrational normal modes. The main functional groups were identified via vibrational analysis, and their absorption bands were assigned. A comparative analysis was performed for the computed and experimental results. Subtle differences were observed between the calculated and experimental UV-Vis spectra. Time-dependent density functional theory (TD-DFT) excitation energies were calculated for five excited electronic states. The calculations were applied to simulate the spectra of (2E)-HIPC, and these simulated spectra exhibited excellent agreement with the experimental spectra. The DFT/B3LYP/6-311++G(d,p) method, after scaling, exhibited better agreement with the experimental values than the results obtained by the HF method. The energy, oscillator strength, and wavelength computed by TD-DFT (IEFPCM) are consistent with the experimental results. The molecular electrostatic potential (MEP) and frontier molecular orbitals (HOMO-LUMO) were also determined to enable prediction of the structural changes and reactive sites. Mulliken population charges of the title molecule were also calculated in the gas phase. The NMR chemical shifts (¹³C and ¹H) were calculated using the gauge-including atomic orbital method and the B3LYP/6-311++G(d,p) approach and were compared with the experimental values. Full article

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16 pages, 781 KiB

Open AccessArticle

Using a Random Secret Pre-Distribution Scheme to Implement Message Authentication in VANETs

by Alan Dahgwo Yein, Yu-Hsiu Huang, Chih-Hsueh Lin, Wen-Shyong Hsieh, Chung-Nan Lee and Zhong-Ting Luo

Appl. Sci. 2015, 5(4), 973-988; https://doi.org/10.3390/app5040973 - 30 Oct 2015

Cited by 7 | Viewed by 4300

Abstract

In recent years, the development of the Intelligent Transportation System (ITS) has increased the popularity of vehicular ad hoc networks (VANET). A VANET is designed to enable vehicles to exchange information about traffic or vehicle conditions to help other vehicles avoid traffic accidents [...] Read more.

In recent years, the development of the Intelligent Transportation System (ITS) has increased the popularity of vehicular ad hoc networks (VANET). A VANET is designed to enable vehicles to exchange information about traffic or vehicle conditions to help other vehicles avoid traffic accidents or traffic jams. To resist malicious attacks, all vehicles must be anonymous and their routings must be untraceable, but still verifiable. The vehicles must trust each other and communicate confidentially. In a VANET, Road Side Units (RSU) are installed on traffic signs or streetlights to help vehicles maintain anonymity, to authenticate messages, or to support confidentiality. However, the coverage of an RSU is limited and the cost of widespread installation is high. RSU installations are incremental, so messages must be authenticated using dense RSUs or sparse RSUs. In this paper, the concept of random key pre-distribution that is used in Wireless Sensor Networks (WSN) is modified to random secret pre-distribution (RSP), which integrates identity-based cryptography (IBC) to produce a message authentication scheme for VANETs in a sparse RSU environment. In the proposed scheme, vehicles follow a process to determine a common secret, allowing them to authenticate each other and obtain the pairing value as a key for use in message authentication and private communication. Evaluation results show that the proposed scheme outperforms related schemes. Full article

(This article belongs to the Special Issue Selected Papers from the International Multi-Conference on Engineering and Technology Innovation 2015 (IMETI2015))

9 pages, 803 KiB

Open AccessArticle

Study on Sintering System of Calcium Barium Sulphoaluminate by XRD Quantitative Analysis

by Jun Chang, Xiaopeng Shang and Jiuye Zhao

Appl. Sci. 2015, 5(4), 989-997; https://doi.org/10.3390/app5040989 - 2 Nov 2015

Cited by 14 | Viewed by 5045

Abstract

Calcium barium sulphoaluminate (CBSA), derived from calcium sulphoaluminate (CSA), has excellent cementitious properties. In this study, the sintering system of CBSA with a theoretical stoichiometric Ca₃BaAl₆SO₁₆ was investigated. Rietveld refinement was performed using TOPAS 4.2 software to quantitatively [...] Read more.

Calcium barium sulphoaluminate (CBSA), derived from calcium sulphoaluminate (CSA), has excellent cementitious properties. In this study, the sintering system of CBSA with a theoretical stoichiometric Ca₃BaAl₆SO₁₆ was investigated. Rietveld refinement was performed using TOPAS 4.2 software to quantitatively calculate the content of CBSA and the actual ionic site occupancy of Ba²⁺. The results indicate that the content of Ca_4−xBa_xAl₆SO₁₆ increases with increasing sintering temperature in the 1200–1400 °C ranges. When sintered at 1400 °C for 180 min, the content of CBSA reaches 88.4%. However, CBSA begins to decompose at 1440 °C, after which the content decreases. The replacement rate of Ba²⁺ was also enlarged by increasing sintering temperature and prolonged sintering time. Sintering at 1400 °C for 180 min is considered as the optimum when replacement rate of Ba²⁺ and the content of CBSA were taken into account. Ca_3.2Ba_0.8Al₆SO₁₆ with a content of 88.4% was synthesized. Full article

(This article belongs to the Special Issue Selected Papers from the International Multi-Conference on Engineering and Technology Innovation 2015 (IMETI2015))

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18 pages, 279 KiB

Open AccessArticle

New Min-Max Approach to Optimal Choice of the Weights in Multi-Criteria Group Decision-Making Problems

by Ming Chen, Zhong Wan and Xiaohong Chen

Appl. Sci. 2015, 5(4), 998-1015; https://doi.org/10.3390/app5040998 - 3 Nov 2015

Cited by 9 | Viewed by 4606

Abstract

In multi-criteria group decision-making (MCGDM), one of the most important problems is to determine the weights of criteria and experts. This paper intends to present two Min-Max models to optimize the point estimates of the weights. Since each expert generally possesses a uniform [...] Read more.

In multi-criteria group decision-making (MCGDM), one of the most important problems is to determine the weights of criteria and experts. This paper intends to present two Min-Max models to optimize the point estimates of the weights. Since each expert generally possesses a uniform viewpoint on the importance (weighted value) of each criterion when he/she needs to rank the alternatives, the objective function in the first model is to minimize the maximum variation between the actual score vector and the ideal one for all the alternatives such that the optimal weights of criteria are consistent in ranking all the alternatives for the same expert. The second model is designed to optimize the weights of experts such that the obtained overall evaluation for each alternative can collect the perspectives of the experts as many as possible. Thus, the objective function in the second model is to minimize the maximum variation between the actual vector of evaluations and the ideal one for all the experts, such that the optimal weights can reduce the difference among the experts in evaluating the same alternative. For the constructed Min-Max models, another focus in this paper is on the development of an efficient algorithm for the optimal weights. Some applications are employed to show the significance of the models and algorithm. From the numerical results, it is clear that the developed Min-Max models more effectively solve the MCGDM problems including the ones with incomplete score matrices, compared with the methods available in the literature. Specifically, by the proposed method, (1) the evaluation uniformity of each expert on the same criteria is guaranteed; (2) The overall evaluation for each alternative can collect the judgements of the experts as many as possible; (3) The highest discrimination degree of the alternatives is obtained. Full article

17 pages, 9810 KiB

Open AccessArticle

The Effects of Cu-doped TiO₂ Thin Films on Hyperplasia, Inflammation and Bacteria Infection

by Linhua Li, Ying Xu, Zhi Zhou, Jiang Chen, Ping Yang, Youhe Yang, Jing’an Li and Nan Huang

Appl. Sci. 2015, 5(4), 1016-1032; https://doi.org/10.3390/app5041016 - 3 Nov 2015

Cited by 23 | Viewed by 5848

Abstract

In the present work, different concentrations of Cu ion (1, 2, 5 and 10 wt %) were doped in the TiO₂ film by a sol-gel method and dip coating process. The morphology of the Cu-doped TiO₂ films were characterized by scanning [...] Read more.

In the present work, different concentrations of Cu ion (1, 2, 5 and 10 wt %) were doped in the TiO₂ film by a sol-gel method and dip coating process. The morphology of the Cu-doped TiO₂ films were characterized by scanning electron microscopy (SEM) and the results showed that the doped Cu made no change to the TiO₂ films. The nitric oxide (NO) release experiment showed that these Cu-doped surfaces showed the ability of catalytic decomposition of exogenous donor S-nitroso-N-acetyl-penicillamine (SNAP) to generate (NO). Based on fluorescence analysis and CCK-8 quantitative results, such films had the ability to inhibit smooth muscle cells adhesion, proliferation and migration with SNAP in vitro. The macrophage adhesion assay and anti-bacterial test proved that such Cu-doped TiO₂ films also possessed anti-inflammatory and anti-bacterial abilities. All the abilities above showed positive correlation with the amounts of the doped Cu. This study suggested that the Cu-doped TiO₂ films were capable of generating physiological levels of NO in the presence of endogenous donor S-nitrosothiols (RSNO), endowing the TiO₂ films with anti-hyperplasia, anti-inflammatory and anti-bacterial abilities. Full article

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17 pages, 5547 KiB

Open AccessArticle

Multi-Bit Data Hiding Scheme for Compressing Secret Messages

by Wen-Chung Kuo, Shao-Hung Kuo and Lih-Chyau Wuu

Appl. Sci. 2015, 5(4), 1033-1049; https://doi.org/10.3390/app5041033 - 4 Nov 2015

Cited by 10 | Viewed by 4792

Abstract

The goal of data hiding techniques usually considers two issues, embedding capacity and image quality. Consequently, in order to achieve high embedding capacity and good image quality, a data hiding scheme combining run-length encoding (RLE) with multi-bit embedding is proposed in this paper. [...] Read more.

The goal of data hiding techniques usually considers two issues, embedding capacity and image quality. Consequently, in order to achieve high embedding capacity and good image quality, a data hiding scheme combining run-length encoding (RLE) with multi-bit embedding is proposed in this paper. This work has three major contributions. First, the embedding capacity is increased 62% because the secret message is compressed before embedding into the cover image. Secondly, the proposed scheme keeps the multi-bit generalized exploiting modification direction (MGEMD) characteristics, which are effective to reduce modified pixels in the cover image and to maintain good stego image quality. Finally, the proposed scheme can prevent modern steganalysis methods, such as RS steganalysis and SPAM (subtractive pixel adjacency matrix), and is compared to MiPOD (minimizing the power of the optimal detector) scheme. From our simulation results and security discussions, we have the following results: First, there are no perceivable differences between the cover images and stego images from human inspection. For example, the average PSNR of stego images is about 44.61 dB when the secret message (80,000 bits) is embedded for test cover images (such as airplane, baboon, Lena) of size 512×512. Secondly, Appl. Sci. 2015, 5 1034 on average, 222,087 pixels were not modified after embedding for the cover image. That is to say, 12% less pixels are modified as compared to the MGEMD method. From the performance discussions, the proposed scheme achieves high embedding capacity and good image quality, but also maintains stego image security. Full article

(This article belongs to the Special Issue Selected Papers from the International Multi-Conference on Engineering and Technology Innovation 2015 (IMETI2015))

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14 pages, 1122 KiB

Open AccessArticle

Development of Polymorphic Genic SSR Markers by Transcriptome Sequencing in the Welsh Onion (Allium fistulosum L.)

by Liuyi Yang, Changlong Wen, Hong Zhao, Qianchun Liu, Jingjing Yang, Lecheng Liu and Yongqin Wang

Appl. Sci. 2015, 5(4), 1050-1063; https://doi.org/10.3390/app5041050 - 5 Nov 2015

Cited by 12 | Viewed by 5195

Abstract

Transcriptome analysis is an efficient way to explore molecular markers in plant species, for which genome sequences have not been published. To address the limited number of markers published for the Welsh onion, this study found 6486 loci of genic simple sequence repeats [...] Read more.

Transcriptome analysis is an efficient way to explore molecular markers in plant species, for which genome sequences have not been published. To address the limited number of markers published for the Welsh onion, this study found 6486 loci of genic simple sequence repeats (SSR), which consisted of 1–5 bp repeat motifs, based on next-generation sequencing (NGS) technology and the RNA-Seq approach. The most abundant motif was mononucleotide (52.33%), followed by trinucleotide (31.96%), and dinucleotide (14.57%). A total of 2525 primer pairs were successfully designed, and 91 out of 311 tested primers were polymorphisms. Overall, 38 genic SSR markers were randomly selected to further validate the degree of genetic diversity, and 22 genic SSR markers (57.89%) showed high levels of polymorphism. The average polymorphism information content (PIC) value and the number of alleles (Na) were 0.63 and 5.27, respectively, and the unweighted pair-group method with arithmetic average (UPGMA) cluster analysis grouped the 22 Allium accessions into three groups with Nei’s similarity coefficients ranging from 0.37 to 0.99. This result suggested that these genic SSR markers could be used to develop a higher resolution genetic map and/or to analyze the phylogenetic relationships among Allium plants in the near future. Full article

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12 pages, 2505 KiB

Open AccessArticle

Spatially Resolved Analysis of Bragg Selectivity

by Tina Sabel

Appl. Sci. 2015, 5(4), 1064-1075; https://doi.org/10.3390/app5041064 - 5 Nov 2015

Cited by 9 | Viewed by 4339

Abstract

This paper targets an inherent control of optical shrinkage in photosensitive polymers, contributing by means of spatially resolved analysis of volume holographic phase gratings. Point by point scanning of the local material response to the Gaussian intensity distribution of the recording beams is [...] Read more.

This paper targets an inherent control of optical shrinkage in photosensitive polymers, contributing by means of spatially resolved analysis of volume holographic phase gratings. Point by point scanning of the local material response to the Gaussian intensity distribution of the recording beams is accomplished. Derived information on the local grating period and grating slant is evaluated by mapping of optical shrinkage in the lateral plane as well as through the depth of the layer. The influence of recording intensity, exposure duration and the material viscosity on the Bragg selectivity is investigated. Full article

(This article belongs to the Section Optics and Lasers)

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10 pages, 3218 KiB

Open AccessCommunication

The Preparation and Application of Dendrimer Modified CdTe/CdS Near Infrared Quantum Dots for Brain Cancer Cells Imaging

by Qingke Bai, Zhenguo Zhao, Haijing Sui, Juan Chen, Xiuhai Xie and Feng Wen

Appl. Sci. 2015, 5(4), 1076-1085; https://doi.org/10.3390/app5041076 - 10 Nov 2015

Cited by 11 | Viewed by 5155

Abstract

The most notable obstacle of brain cancer diagnosis is the inability of delivering imaging agents across the blood-brain barrier (BBB). Recently, quantum dots (QDs) has been demonstrated as an ideal image agent for brain imaging due to their ultra-small size for crossing BBB. [...] Read more.

The most notable obstacle of brain cancer diagnosis is the inability of delivering imaging agents across the blood-brain barrier (BBB). Recently, quantum dots (QDs) has been demonstrated as an ideal image agent for brain imaging due to their ultra-small size for crossing BBB. The plolyamidoamine dendrimers modified CdTe/CdS core/shell near-infrared (NIR) region QDs was successfully synthesized in aqueous solution, and then was characterized by UV-vis absorption, photoluminescence (PL) spectroscopy, dynamic light scattering (DLS), X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM), etc. Our results reveal that the dendrimers modified CdTe/CdS QDs exhibits good water-dispersity and stable NIR fluorescence in various biological environments. In addition, this NIR QDs demonstrates a good biocompatibility and sensitive photoluminescence responses in brain tumor cell imaging. In a word, this type of dendrimers modified NIR CdTe/CdS QDs has huge potential applications in brain imaging. Full article

(This article belongs to the Section Nanotechnology and Applied Nanosciences)

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16 pages, 3072 KiB

Open AccessArticle

Conformance Testing of SGSF-064-1 Using CANoe

by Intaek Kim, Ahmed Al-Hilo, Hyuk Soo Jang and Jong-Geol Yoo

Appl. Sci. 2015, 5(4), 1086-1101; https://doi.org/10.3390/app5041086 - 11 Nov 2015

Cited by 2 | Viewed by 7736

Abstract

In this paper, the authors describe a conformance testing system for SGSF-064-1, the communication protocol between electric vehicles and conductive DC (direct current) chargers in Korea. Since the SGSF-064-1 is based on CAN (controller area network), the testing system was developed by CANoe. [...] Read more.

In this paper, the authors describe a conformance testing system for SGSF-064-1, the communication protocol between electric vehicles and conductive DC (direct current) chargers in Korea. Since the SGSF-064-1 is based on CAN (controller area network), the testing system was developed by CANoe. The DC charger known as EVSE (electric vehicle supply equipment) is the system being tested and the developed system implemented in PC (personal computer). The developed system performs as a tester to ensure that the DC chargers from various manufactures can conform to the communication protocol in SGSF-064-1. The testing system contains four testing modes which also consist of several test cases. Full article

(This article belongs to the Special Issue Smart Grid: Convergence and Interoperability)

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15 pages, 931 KiB

Open AccessArticle

A New Mechanism for THz Detection Based on the Tunneling Effect in Bi-Layer Graphene Nanoribbons

by Antonio Maffucci

Appl. Sci. 2015, 5(4), 1102-1116; https://doi.org/10.3390/app5041102 - 12 Nov 2015

Cited by 5 | Viewed by 4408

Abstract

A new possible mechanism of signal detection in the THz range is investigated, based on the excitation of resonances due to the tunneling effect between two graphene nanoribbons. A simple detector is proposed, where two graphene nanoribbons are used to contact two copper [...] Read more.

A new possible mechanism of signal detection in the THz range is investigated, based on the excitation of resonances due to the tunneling effect between two graphene nanoribbons. A simple detector is proposed, where two graphene nanoribbons are used to contact two copper electrodes. The terminal voltages are shown to exhibit strong resonances when the frequency of an external impinging field is tuned to the characteristic tunneling frequency of the graphene layer pair. An electrodynamic model for the electron transport along the graphene nanoribbons is extended here to include the tunneling effect, and a coupled transmission line model is finally derived. This model is able to predict not only the tunneling resonance, but also the well-known plasmon resonances, related to the propagation of slow surface waves. Full article

(This article belongs to the Section Nanotechnology and Applied Nanosciences)

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17 pages, 817 KiB

Open AccessArticle

Development of a Fractional Order Chaos Synchronization Dynamic Error Detector for Maximum Power Point Tracking of Photovoltaic Power Systems

by Kuo-Nan Yu, Her-Terng Yau and Chi-Kang Liao

Appl. Sci. 2015, 5(4), 1117-1133; https://doi.org/10.3390/app5041117 - 12 Nov 2015

Cited by 6 | Viewed by 4521

Abstract

In recent years, the photovoltaic (PV) power generation system has been widely discussed and researched. Research on electric energy focuses on the development of Maximum Power Point Tracking (MPPT) technology, and many methods have been proposed. However, these studies have a common defect: [...] Read more.

In recent years, the photovoltaic (PV) power generation system has been widely discussed and researched. Research on electric energy focuses on the development of Maximum Power Point Tracking (MPPT) technology, and many methods have been proposed. However, these studies have a common defect: the tracking continues near the maximum power point (MPP), so that the waveform of output power jitters, thus causing power loss and rapid wearing of electronic modules. In order to remedy this defect, this paper proposes a new type of fractional order chaos synchronization dynamic error detector for the MPPT design of a PV power system. In this study, the Sprott chaos synchronization dynamic error system was used to control the pulse width duty cycle of PWM and optimize the power oscillation of a PV power system during steady-state response. The simulation and experimental results showed that the voltage detector proposed in this paper can reduce the power oscillation of a PV power system during steady-state response, and increase the overall system efficiency. From the steady-state responses of MPPT, it can be seen that about 0.2 vibration amplitude can be suppressed with control action. Therefore, about 4% of steady-state vibration energy can be saved. Full article

(This article belongs to the Special Issue Intelligence Computational and Control Approaches for Multi-Physic Coupling Engineering Systems)

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30 pages, 1011 KiB

Open AccessArticle

An Efficient Power Scheduling Scheme for Residential Load Management in Smart Homes

by Muhammad Babar Rasheed, Nadeem Javaid, Ashfaq Ahmad, Zahoor Ali Khan, Umar Qasim and Nabil Alrajeh

Appl. Sci. 2015, 5(4), 1134-1163; https://doi.org/10.3390/app5041134 - 12 Nov 2015

Cited by 123 | Viewed by 9521

Abstract

In this paper, we propose mathematical optimization models of household energy units to optimally control the major residential energy loads while preserving the user preferences. User comfort is modelled in a simple way, which considers appliance class, user preferences and weather conditions. The [...] Read more.

In this paper, we propose mathematical optimization models of household energy units to optimally control the major residential energy loads while preserving the user preferences. User comfort is modelled in a simple way, which considers appliance class, user preferences and weather conditions. The wind-driven optimization (WDO) algorithm with the objective function of comfort maximization along with minimum electricity cost is defined and implemented. On the other hand, for maximum electricity bill and peak reduction, min-max regret-based knapsack problem (K-WDO) algorithm is used. To validate the effectiveness of the proposed algorithms, extensive simulations are conducted for several scenarios. The simulations show that the proposed algorithms provide with the best optimal results with a fast convergence rate, as compared to the existing techniques. Full article

(This article belongs to the Special Issue Smart Grid: Convergence and Interoperability)

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20 pages, 4532 KiB

Open AccessArticle

Contribution of TEMPO-Oxidized Cellulose Gel in the Formation of Flower-Like Zinc Oxide Superstructures: Characterization of the TOCgel/ZnO Composite Films

by Khalil Jradi, Chloé Maury and Claude Daneault

Appl. Sci. 2015, 5(4), 1164-1183; https://doi.org/10.3390/app5041164 - 13 Nov 2015

Cited by 17 | Viewed by 7995

Abstract

In the present paper, we report on a simple and new approach for the synthesis of hierarchical flower-like zinc oxide superstructures ZnO (FL) in the presence of the TEMPO-oxidized cellulose gel (TOCgel) through a room temperature sol-gel process in aqueous medium. Resulting composite [...] Read more.

In the present paper, we report on a simple and new approach for the synthesis of hierarchical flower-like zinc oxide superstructures ZnO (FL) in the presence of the TEMPO-oxidized cellulose gel (TOCgel) through a room temperature sol-gel process in aqueous medium. Resulting composite films based on TOCgel and ZnO were investigated by several techniques including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and mechanical tests. SEM images demonstrated the formation of well-shaped flower-like ZnO superstructures within the fibrous structure of the TOCgel with a uniform diameter (~5 μm). FTIR and XPS results clearly confirmed the formation of such ZnO structures. We suggested that the carboxylate groups of TOCgel fibers act as capping agents and promote the construction of such flower-like ZnO via a nucleation-growth process. A proposed mechanism based on the oriented attachment-driven growth was discussed in order to explain the formation of ZnO (FL). The photocatalytic activity of the TOCgel/ZnO composite in the degradation of methylene blue (MB) under UV irradiation was clearly confirmed. Finally, mechanical tests demonstrated that the former TOCgel/ZnO film maintained a good flexibility (bent up to ~120°) without losing its photocatalytic activity. Full article

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12 pages, 1811 KiB

Open AccessArticle

The Effect of Trifluoroethanol and Glycerol on the Thermal Properties of Collagen Using Optical Displacement-Enhanced Heterodyne Polarimeter

by Chien-Ming Wu, Horn-Haw Chen, Kai-Han Tseng and Hung-Wei Chen

Appl. Sci. 2015, 5(4), 1184-1195; https://doi.org/10.3390/app5041184 - 13 Nov 2015

Cited by 1 | Viewed by 4262

Abstract

An angular displacement-enhanced heterodyne polarimeter has been employed to investigate the interplay between trifluoroethanol (TFE) and glycerol on the thermal denaturation of type I collagen. The concentration of the collagen solution was fixed at 0.341 (mg/mL), and was heated from 25 °C to [...] Read more.

An angular displacement-enhanced heterodyne polarimeter has been employed to investigate the interplay between trifluoroethanol (TFE) and glycerol on the thermal denaturation of type I collagen. The concentration of the collagen solution was fixed at 0.341 (mg/mL), and was heated from 25 °C to 55 °C. TFE solutions with concentrations of 5%, 10%, 15%, 20%, 40% and 80% (v/v) were prepared and the phase change was recorded for the determination of thermal denaturation. It was observed that the thermal denaturation temperature (T_d) is decreased with increasing TFE concentration due to the partial cleavage of the triple-helical structure. With TFE concentration higher than 20% (v/v), the degree of optical rotation appears to be nearly the same, reflecting that the collagen triple helices have been completely destructed. Moreover, the addition of glycerol in inhibiting the thermal denaturation of collagen is investigated. It has been shown that glycerol can improve the thermal denaturation of both collagen and TFE-mixed collagen. Experimental results show that, in the presence of 2 M glycerol, the T_d of collagen remained at around 41.9 °C, meanwhile the T_d of 20% (v/v) TFE-mixed collagen is significantly restored to 32.8 °C. Full article

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15 pages, 3418 KiB

Open AccessArticle

Polypropylene/Graphene and Polypropylene/Carbon Fiber Conductive Composites: Mechanical, Crystallization and Electromagnetic Properties

by Chien-Lin Huang, Ching-Wen Lou, Chi-Fan Liu, Chen-Hung Huang, Xiao-Min Song and Jia-Horng Lin

Appl. Sci. 2015, 5(4), 1196-1210; https://doi.org/10.3390/app5041196 - 13 Nov 2015

Cited by 87 | Viewed by 8492

Abstract

This study aims to examine the properties of composites that different carbon materials with different measurements can reinforce. Using a melt compounding method, this study combines polypropylene (PP) and graphene nano-sheets (GNs) or carbon fiber (CF) to make PP/GNs and PP/CF conductive composites, [...] Read more.

This study aims to examine the properties of composites that different carbon materials with different measurements can reinforce. Using a melt compounding method, this study combines polypropylene (PP) and graphene nano-sheets (GNs) or carbon fiber (CF) to make PP/GNs and PP/CF conductive composites, respectively. The DSC results and optical microscopic observation show that both GNs and CF enable PP to crystalize at a high temperature. The tensile modulus of PP/GNs and PP/CF conductive composites remarkably increases as a result of the increasing content of conductive fillers. The tensile strength of the PP/GNs conductive composites is inversely proportional to the loading level of GNs. Containing 20 wt% of GNs, the PP/GNs conductive composites have an optimal conductivity of 0.36 S/m and an optimal EMI SE of 13 dB. PP/CF conductive composites have an optimal conductivity of 10⁻⁶ S/m when composed of no less than 3 wt% of CF, and an optimal EMI SE of 25 dB when composed of 20 wt% of CF. Full article

(This article belongs to the Special Issue Selected Papers from the International Multi-Conference on Engineering and Technology Innovation 2015 (IMETI2015))

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10 pages, 720 KiB

Open AccessCommunication

Microwave-Assisted Synthesis and Antifungal Activity of Some Novel Thioethers Containing 1,2,4-Triazole Moiety

by Li-Jing Min, Yan-Xia Shi, Hong-Ke Wu, Zhao-Hui Sun, Xing-Hai Liu, Bao-Ju Li and Yong-Gang Zhang

Appl. Sci. 2015, 5(4), 1211-1220; https://doi.org/10.3390/app5041211 - 16 Nov 2015

Cited by 10 | Viewed by 4799

Abstract

A series of novel thioether derivatives containing 1,2,4-triazole moiety were designed and synthesized from 4-chlorophenol and ethyl 2-chloroacetate as starting materials by multi-step reactions under microwave irradiation, and their structures were characterized by ¹H-NMR, MS and elemental analysis. The antifungal activity of [...] Read more.

A series of novel thioether derivatives containing 1,2,4-triazole moiety were designed and synthesized from 4-chlorophenol and ethyl 2-chloroacetate as starting materials by multi-step reactions under microwave irradiation, and their structures were characterized by ¹H-NMR, MS and elemental analysis. The antifungal activity of title compounds was determined. The results indicated that some of title compounds exhibited moderate antifungal activity. Full article

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14 pages, 4259 KiB

Open AccessArticle

Effect of Ta₂O₅ and Nb₂O₅ Dopants on the Stable Dielectric Properties of BaTiO₃–(Bi_0.5Na_0.5)TiO₃-Based Materials

by Sea-Fue Wang, Yung-Fu Hsu, Yu-Wen Hung and Yi-Xin Liu

Appl. Sci. 2015, 5(4), 1221-1234; https://doi.org/10.3390/app5041221 - 16 Nov 2015

Cited by 16 | Viewed by 6338

Abstract

In this study, BaTiO₃–(Bi_0.5Na_0.5)TiO₃ ceramics with various amounts of Ta₂O₅ dopant were investigated for their ability to enhance high-temperature stability to meet X9R specifications. The results were compared to those for ceramics with [...] Read more.

In this study, BaTiO₃–(Bi_0.5Na_0.5)TiO₃ ceramics with various amounts of Ta₂O₅ dopant were investigated for their ability to enhance high-temperature stability to meet X9R specifications. The results were compared to those for ceramics with the common Nb₂O₅ additive. The best composition appeared to be 0.9BaTiO₃–0.1(Bi_0.5Na_0.5)TiO₃ with 2 mol% Ta₂O₅ dopant sintered at 1215 °C, which had a dielectric constant of 1386, a tanδ value of 1.8%, temperature coefficients of capacitance (TCCs) of −1.3% and 1.2%, and electrical resistivities of 2.8 × 10¹² and 1.5 × 10¹⁰ Ω·cm at 25 °C and 200 °C, respectively. Its microstructure consisted of fine equiaxed grains with a perovskite structure and an average grain size of 0.46 μm and some rod-like grains of second-phase Ba₆Ti₁₇O₄₀ with a size of approximately 3.2 μm. The Ta₂O₅ dopant caused a reduction in the grain size and a slight increase in trapped pores. The temperature dependence of the dielectric constant flattened and the Curie point was dramatically suppressed with the addition of Ta₂O₅ dopant, leading to smooth dielectric temperature characteristics over a relatively broad temperature range. The X9R formulations and their dielectric properties were highly repeatable in this study. Full article

(This article belongs to the Special Issue Ferroelectric Ceramics)

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17 pages, 2375 KiB

Open AccessArticle

Agent Based Fuzzy T-S Multi-Model System and Its Applications

by Xiaopeng Zhao

Appl. Sci. 2015, 5(4), 1235-1251; https://doi.org/10.3390/app5041235 - 16 Nov 2015

Cited by 2 | Viewed by 3675

Abstract

Based on the basic concepts of agent and fuzzy T-S model, an agent based fuzzy T-S multi-model (ABFT-SMM) system is proposed in this paper. Different from the traditional method, the parameters and the membership value of the agent can be adjusted along with [...] Read more.

Based on the basic concepts of agent and fuzzy T-S model, an agent based fuzzy T-S multi-model (ABFT-SMM) system is proposed in this paper. Different from the traditional method, the parameters and the membership value of the agent can be adjusted along with the process. In this system, each agent can be described as a dynamic equation, which can be seen as the local part of the multi-model, and it can execute the task alone or collaborate with other agents to accomplish a fixed goal. It is proved in this paper that the agent based fuzzy T-S multi-model system can approximate any linear or nonlinear system at arbitrary accuracy. The applications to the benchmark problem of chaotic time series prediction, water heater system and waste heat utilizing process illustrate the viability and the efficiency of the mentioned approach. At the same time, the method can be easily used to a number of engineering fields, including identification, nonlinear control, fault diagnostics and performance analysis. Full article

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20 pages, 2865 KiB

Open AccessArticle

Dispersion of Functionalized Silica Micro- and Nanoparticles into Poly(nonamethylene Azelate) by Ultrasonic Micro-Molding

by Angélica Díaz, María T. Casas and Jordi Puiggalí

Appl. Sci. 2015, 5(4), 1252-1271; https://doi.org/10.3390/app5041252 - 17 Nov 2015

Cited by 11 | Viewed by 5602

Abstract

Ultrasound micro-molding technology has proved useful in processing biodegradable polymers with minimum material loss. This makes this technology particularly suitable for the production of biomedical microdevices. The use of silica (SiO₂) nanoparticles is also interesting because of advantages like low cost [...] Read more.

Ultrasound micro-molding technology has proved useful in processing biodegradable polymers with minimum material loss. This makes this technology particularly suitable for the production of biomedical microdevices. The use of silica (SiO₂) nanoparticles is also interesting because of advantages like low cost and enhancement of final properties. Evaluation of the capacity to create a homogeneous dispersion of particles is crucial. Specifically, this feature was explored taking into account micro- and nano-sized silica particles and a biodegradable polyester derived from 1,9-nonanodiol and azelaic acid as a matrix. Results demonstrated that composites could be obtained with up to 6 wt. % of silica and that no degradation occurred even if particles were functionalized with a compatibilizer like (3-aminopropyl) triethoxysilane. Incorporation of nanoparticles should have a great influence on properties. Specifically, the effect on crystallization was evaluated by calorimetric and optical microscopy analyses. The overall crystallization rate was enhanced upon addition of functionalized silica nanospheres, even at the low percentage of 3 wt. %. This increase was mainly due to the ability of nanoparticles to act as heterogeneous nuclei during crystallization. However, the enhancement of the secondary nucleation process also played a significant role, as demonstrated by Lauritzen and Hoffmann analysis. Full article

(This article belongs to the Special Issue Acoustic and Elastic Waves: Recent Trends in Science and Engineering)

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26 pages, 1291 KiB

Open AccessArticle

A New Approach to Optimal Allocation of Reactive Power Ancillary Service in Distribution Systems in the Presence of Distributed Energy Resources

by Abouzar Samimi and Ahad Kazemi

Appl. Sci. 2015, 5(4), 1284-1309; https://doi.org/10.3390/app5041284 - 20 Nov 2015

Cited by 13 | Viewed by 5590

Abstract

One of the most important Distribution System Operators (DSO) schemes addresses the Volt/Var control (VVC) problem. Developing a cost-based reactive power dispatch model for distribution systems, in which the reactive powers are appropriately priced, can motivate Distributed Energy Resources (DERs) to participate actively [...] Read more.

One of the most important Distribution System Operators (DSO) schemes addresses the Volt/Var control (VVC) problem. Developing a cost-based reactive power dispatch model for distribution systems, in which the reactive powers are appropriately priced, can motivate Distributed Energy Resources (DERs) to participate actively in VVC. In this paper, new reactive power cost models for DERs, including synchronous machine-based DGs and wind turbines (WTs), are formulated based on their capability curves. To address VVC in the context of competitive electricity markets in distribution systems, first, in a day-ahead active power market, the initial active power dispatch of generation units is estimated considering environmental and economic aspects. Based on the results of the initial active power dispatch, the proposed VVC model is executed to optimally allocate reactive power support among all providers. Another novelty of this paper lies in the pricing scheme that rewards transformers and capacitors for tap and step changing, respectively, while incorporating the reactive power dispatch model. A Benders decomposition algorithm is employed as a solution method to solve the proposed reactive power dispatch, which is a mixed integer non-linear programming (MINLP) problem. Finally, a typical 22-bus distribution network is used to verify the efficiency of the proposed method. Full article

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13 pages, 1817 KiB

Open AccessArticle

Extremely Nonlinear Optics Using Shaped Pulses Spectrally Broadened in an Argon- or Sulfur Hexafluoride-Filled Hollow-Core Fiber

by Andreas Hoffmann, Michael Zürch and Christian Spielmann

Appl. Sci. 2015, 5(4), 1310-1322; https://doi.org/10.3390/app5041310 - 20 Nov 2015

Cited by 5 | Viewed by 7106

Abstract

In this contribution we present a comparison of the performance of spectrally broadened ultrashort pulses using a hollow-core fiber either filled with argon or sulfur hexafluoride (SF₆) for demanding pulse-shaping experiments. The benefits of both gases for pulse-shaping are studied in [...] Read more.

In this contribution we present a comparison of the performance of spectrally broadened ultrashort pulses using a hollow-core fiber either filled with argon or sulfur hexafluoride (SF₆) for demanding pulse-shaping experiments. The benefits of both gases for pulse-shaping are studied in the highly nonlinear process of high-harmonic generation. In this setup, temporally shaping the driving laser pulse leads to spectrally shaping of the output extreme ultraviolet (XUV) spectrum, where total yield and spectral selectivity in the XUV are the targets of the optimization approach. The effect of using sulfur hexafluoride for pulse-shaping the XUV yield can be doubled compared to pulse compression and pulse-shaping using argon and the spectral range for selective optimization of a single harmonic can be extended. The obtained results are of interest for extending the range of ultrafast science applications drawing on tailored XUV fields. Full article

(This article belongs to the Special Issue Fibre Lasers: From Underlying Science and Technology to Applications)

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14 pages, 581 KiB

Open AccessArticle

High-Power Continuous-Wave Directly-Diode-Pumped Fiber Raman Lasers

by Tianfu Yao, Achar V. Harish, Jayanta K. Sahu and Johan Nilsson

Appl. Sci. 2015, 5(4), 1323-1336; https://doi.org/10.3390/app5041323 - 20 Nov 2015

Cited by 90 | Viewed by 7265

Abstract

We describe novel fiber Raman lasers pumped directly by spectrally combined high power multimode laser diodes at ~975 nm and emitting at ~1019 nm. With a commercial multimode graded-index fiber, we reached 20 W of laser output power with a record slope efficiency [...] Read more.

We describe novel fiber Raman lasers pumped directly by spectrally combined high power multimode laser diodes at ~975 nm and emitting at ~1019 nm. With a commercial multimode graded-index fiber, we reached 20 W of laser output power with a record slope efficiency of 80%. With an in-house double-clad fiber, the beam quality improved to M2 = 1.9, albeit with lower output power and slope efficiency due to higher fiber loss. We believe this is the first publication of a fiber Raman laser cladding-pumped directly by diodes. Full article

(This article belongs to the Special Issue Fibre Lasers: From Underlying Science and Technology to Applications)

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13 pages, 2370 KiB

Open AccessArticle

An Experimental Study on Mechanical Modeling of Ceramics Based on Microstructure

by Ya-Nan Zhang, Bin Lin, Jian-Jun Liu, Xiao-Fei Song and Jie Yang Key

Appl. Sci. 2015, 5(4), 1337-1349; https://doi.org/10.3390/app5041337 - 23 Nov 2015

Cited by 5 | Viewed by 5007

Abstract

The actual grinding result of ceramics has not been well predicted by the present mechanical models. No allowance is made for direct effects of materials microstructure and almost all the mechanical models were obtained based on crystalline ceramics. In order to improve the [...] Read more.

The actual grinding result of ceramics has not been well predicted by the present mechanical models. No allowance is made for direct effects of materials microstructure and almost all the mechanical models were obtained based on crystalline ceramics. In order to improve the mechanical models of ceramics, surface grinding experiments on crystalline ceramics and non-crystalline ceramics were conducted in this research. The normal and tangential grinding forces were measured to calculate single grit force and specific grinding energy. Grinding surfaces were observed. For crystalline alumina ceramics, the predictive modeling of normal force per grit fits well with the experimental result, when the maximum undeformed chip thickness is less than a critical depth, which turns out to be close to the grain size of alumina. Meanwhile, there is a negative correlation between the specific grinding energy and the maximum undeformed chip thickness. With the decreasing maximum undeformed chip thickness, the proportions of ductile removal and transgranular fracture increase. However, the grinding force models are not applicable for non-crystalline ceramic fused silica and the specific grinding energy fluctuates irregularly as a function of maximum undeformed chip thickness seen from the experiment. Full article

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20 pages, 814 KiB

Open AccessArticle

Design and Applications of In-Cavity Pulse Shaping by Spectral Sculpturing in Mode-Locked Fibre Lasers

by Sonia Boscolo, Junsong Peng and Christophe Finot

Appl. Sci. 2015, 5(4), 1379-1398; https://doi.org/10.3390/app5041379 - 25 Nov 2015

Cited by 12 | Viewed by 6572

Abstract

We review our recent progress on the realisation of pulse shaping in passively-mode-locked fibre lasers by inclusion of an amplitude and/or phase spectral filter into the laser cavity. We numerically show that depending on the amplitude transfer function of the in-cavity filter, various [...] Read more.

We review our recent progress on the realisation of pulse shaping in passively-mode-locked fibre lasers by inclusion of an amplitude and/or phase spectral filter into the laser cavity. We numerically show that depending on the amplitude transfer function of the in-cavity filter, various regimes of advanced waveform generation can be achieved, including ones featuring parabolic-, flat-top- and triangular-profiled pulses. An application of this approach using a flat-top spectral filter is shown to achieve the direct generation of high-quality sinc-shaped optical Nyquist pulses with a widely tunable bandwidth from the laser oscillator. We also present the operation of an ultrafast fibre laser in which conventional soliton, dispersion-managed soliton (stretched-pulse) and dissipative soliton mode-locking regimes can be selectively and reliably targeted by adaptively changing the dispersion profile and bandwidth programmed on an in-cavity programmable filter. The results demonstrate the strong potential of an in-cavity spectral pulse shaper for achieving a high degree of control over the dynamics and output of mode-locked fibre lasers. Full article

(This article belongs to the Special Issue Fibre Lasers: From Underlying Science and Technology to Applications)

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13 pages, 838 KiB

Open AccessArticle

NHL and RCGA Based Multi-Relational Fuzzy Cognitive Map Modeling for Complex Systems

by Zhen Peng, Lifeng Wu and Zhenguo Chen

Appl. Sci. 2015, 5(4), 1399-1411; https://doi.org/10.3390/app5041399 - 27 Nov 2015

Cited by 7 | Viewed by 4839

Abstract

In order to model multi-dimensions and multi-granularities oriented complex systems, this paper firstly proposes a kind of multi-relational Fuzzy Cognitive Map (FCM) to simulate the multi-relational system and its auto construct algorithm integrating Nonlinear Hebbian Learning (NHL) and Real Code Genetic Algorithm (RCGA). [...] Read more.

In order to model multi-dimensions and multi-granularities oriented complex systems, this paper firstly proposes a kind of multi-relational Fuzzy Cognitive Map (FCM) to simulate the multi-relational system and its auto construct algorithm integrating Nonlinear Hebbian Learning (NHL) and Real Code Genetic Algorithm (RCGA). The multi-relational FCM fits to model the complex system with multi-dimensions and multi-granularities. The auto construct algorithm can learn the multi-relational FCM from multi-relational data resources to eliminate human intervention. The Multi-Relational Data Mining (MRDM) algorithm integrates multi-instance oriented NHL and RCGA of FCM. NHL is extended to mine the causal relationships between coarse-granularity concept and its fined-granularity concepts driven by multi-instances in the multi-relational system. RCGA is used to establish high-quality high-level FCM driven by data. The multi-relational FCM and the integrating algorithm have been applied in complex system of Mutagenesis. The experiment demonstrates not only that they get better classification accuracy, but it also shows the causal relationships among the concepts of the system. Full article

(This article belongs to the Special Issue Applied Artificial Neural Network)

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19 pages, 1898 KiB

Open AccessArticle

Enhancement of Spatial Resolution Using a Metamaterial Sensor in Nondestructive Evaluation

by Adriana Savin, Alina Bruma, Rozina Steigmann, Nicoleta Iftimie and Dagmar Faktorova

Appl. Sci. 2015, 5(4), 1412-1430; https://doi.org/10.3390/app5041412 - 27 Nov 2015

Cited by 16 | Viewed by 6248

Abstract

The current stage of non-destructive evaluation techniques imposes the development of new electromagnetic methods that are based on high spatial resolution and increased sensitivity. Printed circuit boards, integrated circuit boards, composite materials with polymeric matrix containing conductive fibers, as well as some types [...] Read more.

The current stage of non-destructive evaluation techniques imposes the development of new electromagnetic methods that are based on high spatial resolution and increased sensitivity. Printed circuit boards, integrated circuit boards, composite materials with polymeric matrix containing conductive fibers, as well as some types of biosensors are devices of interest in using such evaluation methods. In order to achieve high performance, the work frequencies must be either radiofrequencies or microwaves. At these frequencies, at the dielectric/conductor interface, plasmon polaritons can appear, propagating between conductive regions as evanescent waves. Detection of these waves, containing required information, can be done using sensors with metamaterial lenses. We propose in this paper the enhancement of the spatial resolution using electromagnetic methods, which can be accomplished in this case using evanescent waves that appear in the current study in slits of materials such as the spaces between carbon fibers in Carbon Fibers Reinforced Plastics or in materials of interest in the nondestructive evaluation field with industrial applications, where microscopic cracks are present. We propose herein a unique design of the metamaterials for use in nondestructive evaluation based on Conical Swiss Rolls configurations, which assure the robust concentration/focusing of the incident electromagnetic waves (practically impossible to be focused using classical materials), as well as the robust manipulation of evanescent waves. Applying this testing method, spatial resolution of approximately λ/2000 can be achieved. This testing method can be successfully applied in a variety of applications of paramount importance such as defect/damage detection in materials used in a variety of industrial applications, such as automotive and aviation technologies. Full article

(This article belongs to the Special Issue Acoustic and Elastic Waves: Recent Trends in Science and Engineering)

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9 pages, 1815 KiB

Open AccessArticle

Theoretical Analysis of Dependence of Nonlinear Effects in Mode-Locked Yb:YAG Lasers with a Highly Nonlinear Intra-Cavity Medium

by Takeshi Yoshida, Hiroaki Okunishi, Keisuke Kyomoto, Kento Kato, Kyosuke Shimabayashi, Shinichi Inayoshi, Motoki Morioka and Sakae Kawato

Appl. Sci. 2015, 5(4), 1431-1439; https://doi.org/10.3390/app5041431 - 27 Nov 2015

Cited by 5 | Viewed by 4656

Abstract

Nonlinear ultrashort pulse propagation in a mode-locked Yb:YAG laser with a highly nonlinear intra-cavity medium is analyzed using a nonlinear Schrodinger equation. The output spectra are extended by the increased laser intensity, and spectral bandwidths wider than those of the gain medium are [...] Read more.

Nonlinear ultrashort pulse propagation in a mode-locked Yb:YAG laser with a highly nonlinear intra-cavity medium is analyzed using a nonlinear Schrodinger equation. The output spectra are extended by the increased laser intensity, and spectral bandwidths wider than those of the gain medium are achieved. Moreover, pulse widths are shortened by increased laser intensity to considerably less than those of the gain medium. The simulation results qualitatively agree with the experimental results. Full article

(This article belongs to the Special Issue Diode-Pumped, Ultra-Short Pulse Lasers)

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27 pages, 954 KiB

Open AccessArticle

Quantum Wind Driven Optimization for Unmanned Combat Air Vehicle Path Planning

by Yongquan Zhou, Zongfan Bao, Rui Wang, Shilei Qiao and Yuxiang Zhou

Appl. Sci. 2015, 5(4), 1457-1483; https://doi.org/10.3390/app5041457 - 30 Nov 2015

Cited by 24 | Viewed by 5784

Abstract

Unmanned combat air vehicle (UCAV) path planning aims to calculate the optimal or suboptimal flight path considering the different threats and constraints under the complex battlefield environment. This flight path can help the UCAV avoid enemy threats and improve the efficiency of the [...] Read more.

Unmanned combat air vehicle (UCAV) path planning aims to calculate the optimal or suboptimal flight path considering the different threats and constraints under the complex battlefield environment. This flight path can help the UCAV avoid enemy threats and improve the efficiency of the investigation. This paper presents a new quantum wind driven optimization (QWDO) for the path planning of UCAV. QWDO algorithm uses quantum rotation gate strategy on population evolution and the quantum non-gate strategy to realize the individual variation of population. These operations improve the diversity of population and avoid premature convergence. This paper tests this optimization in two instances. The experimental results show that the proposed algorithm is feasible in these two cases. Compared to quantum bat algorithm (QBA), quantum particle swarm optimization (QPSO), wind driven optimization (WDO), bat algorithm (BA), particle swarm optimization (PSO), and differential evolution (DE), the QWDO algorithm exhibited better performance. The simulation results demonstrate that the QWDO algorithm is an effective and feasible method for solving UCAV path planning. Full article

(This article belongs to the Special Issue Intelligence Computational and Control Approaches for Multi-Physic Coupling Engineering Systems)

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10 pages, 975 KiB

Open AccessArticle

Trichromatic π-Pulse for Ultrafast Total Inversion of a Four-Level Ladder System

by Carles Serrat, Montserrat Corbera and John Afa

Appl. Sci. 2015, 5(4), 1484-1493; https://doi.org/10.3390/app5041484 - 30 Nov 2015

Cited by 3 | Viewed by 3940

Abstract

We present a numerical solution for complete population inversion in a four-level ladder system obtained by using a full π-pulse illumination scheme with resonant ultrashort phase-locked Gaussian laser pulses. We find that a set of pulse areas such as √3π , √2π , [...] Read more.

We present a numerical solution for complete population inversion in a four-level ladder system obtained by using a full π-pulse illumination scheme with resonant ultrashort phase-locked Gaussian laser pulses. We find that a set of pulse areas such as √3π , √2π , and √3π completely inverts the four-level system considering identical effective dipole coupling coefficients. The solution is consistent provided the involved electric fields are not too strong and it is amply accurate also in the case of diverse transition dipole moments. We study the effect of detuning and chirp of the laser pulses on the complete population inversion using the level structure of atomic sodium interacting with ps and fs pulses as an example. Our result opens the door for multiple applications such as efficient ultrashort pulse lasing in the UV or the engineering of quantum states for quantum computing. Full article

(This article belongs to the Section Optics and Lasers)

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9 pages, 1177 KiB

Open AccessArticle

Luminescent Properties of Sr₄Si₃O₈Cl₄:Eu²⁺, Bi³⁺ Phosphors for Near UV InGaN-Based Light-Emitting-Diodes

by Wangqing Shen, Yiwen Zhu and Zhengling Wang

Appl. Sci. 2015, 5(4), 1494-1502; https://doi.org/10.3390/app5041494 - 1 Dec 2015

Cited by 10 | Viewed by 4731

Abstract

Sr₄Si₃O₈Cl₄ co-doped with Eu²⁺, Bi³⁺ were prepared by the high temperature reaction. The structure and luminescent properties of Sr₄Si₃O₈Cl₄:Eu²⁺, Bi³⁺ were investigated. [...] Read more.

Sr₄Si₃O₈Cl₄ co-doped with Eu²⁺, Bi³⁺ were prepared by the high temperature reaction. The structure and luminescent properties of Sr₄Si₃O₈Cl₄:Eu²⁺, Bi³⁺ were investigated. With the introduction of Bi³⁺, luminescent properties of these phosphors have been optimized. Compared with Sr_3.90Si₃O₈Cl₄:0.10Eu²⁺, the blue-green phosphor Sr_3.50Si₃O₈Cl₄:0.10Eu²⁺, 0.40Bi³⁺ shows stronger blue-green emission with broader excitation in near-UV range. Bright blue-green light from the LED means this phosphor can be observed by the naked eye. Hence, it may have an application in near UV LED chips. Full article

(This article belongs to the Section Optics and Lasers)

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25 pages, 449 KiB

Open AccessArticle

Privacy-Preserving Smart Metering with Authentication in a Smart Grid

by Jun Beom Hur, Dong Young Koo and Young Joo Shin

Appl. Sci. 2015, 5(4), 1503-1527; https://doi.org/10.3390/app5041503 - 1 Dec 2015

Cited by 21 | Viewed by 6347

Abstract

The traditional security objectives of smart grids have been availability, integrity, and confidentiality. However, as the grids incorporate smart metering and load management, user and corporate privacy is increasingly becoming an issue in smart grid networks. Although transmitting current power consumption levels to [...] Read more.

The traditional security objectives of smart grids have been availability, integrity, and confidentiality. However, as the grids incorporate smart metering and load management, user and corporate privacy is increasingly becoming an issue in smart grid networks. Although transmitting current power consumption levels to the supplier or utility from each smart meter at short intervals has an advantage for the electricity supplier’s planning and management purposes, it threatens user privacy by disclosing fine-grained consumption data and usage behavior to utility providers. In this study, we propose a distributed incremental data aggregation scheme where all smart meters on an aggregation path are involved in routing the data from the source meter to the collection unit. User privacy is preserved by symmetric homomorphic encryption, which allows smart meters to participate in the aggregation without seeing any intermediate or final result. Aggregated data is further integrated with an aggregate signature to achieve data integrity and smart meter authentication in such a way that dishonest or fake smart meters cannot falsify data en route. Only the collection unit can obtain the aggregated data and verify its integrity while the individual plain data are not exposed to the collection unit. Therefore, user privacy and security are improved for the smart metering in a smart grid network. Full article

(This article belongs to the Special Issue Smart Grid: Convergence and Interoperability)

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19 pages, 3313 KiB

Open AccessArticle

A Local Texture-Based Superpixel Feature Coding for Saliency Detection Combined with Global Saliency

by Bingfei Nan, Zhichun Mu, Long Chen and Jian Cheng

Appl. Sci. 2015, 5(4), 1528-1546; https://doi.org/10.3390/app5041528 - 2 Dec 2015

Cited by 4 | Viewed by 6318

Abstract

Because saliency can be used as the prior knowledge of image content, saliency detection has been an active research area in image segmentation, object detection, image semantic understanding and other relevant image-based applications. In the case of saliency detection from cluster scenes, the [...] Read more.

Because saliency can be used as the prior knowledge of image content, saliency detection has been an active research area in image segmentation, object detection, image semantic understanding and other relevant image-based applications. In the case of saliency detection from cluster scenes, the salient object/region detected needs to not only be distinguished clearly from the background, but, preferably, to also be informative in terms of complete contour and local texture details to facilitate the successive processing. In this paper, a Local Texture-based Region Sparse Histogram (LTRSH) model is proposed for saliency detection from cluster scenes. This model uses a combination of local texture patterns and color distribution as well as contour information to encode the superpixels to characterize the local feature of image for region contrast computing. Combining the region contrast as computed with the global saliency probability, a full-resolution salient map, in which the salient object/region detected adheres more closely to its inherent feature, is obtained on the bases of the corresponding high-level saliency spatial distribution as well as on the pixel-level saliency enhancement. Quantitative comparisons with five state-of-the-art saliency detection methods on benchmark datasets are carried out, and the comparative results show that the method we propose improves the detection performance in terms of corresponding measurements. Full article

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13 pages, 2436 KiB

Open AccessArticle

Synthesis and Physical and Chemical Properties of Hypergolic Chemicals such as N,N,N-Trimethylhydrazinium and 1-Ethyl-4-Methyl-1,2,4-Triazolium Salts

by Young-Seok Kim, Gi-Hyuk Son, Tae-Kyung Na and Seong-Ho Choi

Appl. Sci. 2015, 5(4), 1547-1559; https://doi.org/10.3390/app5041547 - 2 Dec 2015

Cited by 10 | Viewed by 5634

Abstract

Hypergolic chemicals N,N,N-trimethylhydrazinium iodide, [TMH]⁺[I]⁻, and 1-ethyl-4-methyl-1,2,4-triazolium iodide, [EMT]⁺[I]⁻ were firstly synthesized by nucleophilic substitution (S_N2). The successful synthesis of hypergolic chemicals [TMH]⁺[I]⁻ and [EMT]⁺ [...] Read more.

Hypergolic chemicals N,N,N-trimethylhydrazinium iodide, [TMH]⁺[I]⁻, and 1-ethyl-4-methyl-1,2,4-triazolium iodide, [EMT]⁺[I]⁻ were firstly synthesized by nucleophilic substitution (S_N2). The successful synthesis of hypergolic chemicals [TMH]⁺[I]⁻ and [EMT]⁺[I]⁻ was confirmed by IR and ¹H-NMR spectroscopy and, GC-mass spectrometry. Subsequently the hypergolic chemicals [TMH]⁺[X]⁻ (X = CN⁻, N₃⁻, NO₃⁻, NO₂⁻, ClO₄⁻, AlCl₄⁻) were prepared via an ion exchange reaction from [TMH]⁺[I]⁻ and [EMT]⁺[I]⁻, respectively. After that, a mixture of hypergolic chemicals was prepared by dissolving the synthesized hypergolic chemicals in 2-hydroxyethylhydrazine (HOCH₂CH₂NHNH₂). The physical and chemical properties of the mixture such as decomposition temperature (T_d), density (d), viscosity (η), and decomposition energy (ΔH_d) was then evaluated to determine suitability for use as liquid rocket fuels. The ignition delay (ID) time of the mixture of hypergolic chemicals with [TMH]⁺[N₃]⁻ and [TMH]⁺[CN]⁻ using H₂O₂ as an oxidizer was determined as 55.6 ms and 97.4 ms; respectively. The ID time of the mixture of hypergolic chemicals with [EMT]⁺[N₃]⁻; [EMT]⁺[CN]⁻; [EMT]⁺[AlCl₄]⁻; and [EMT]⁺[I]⁻ using H₂O₂ as an oxidizer was also determined as 18.0 ms; 32.6 ms; 27.6 ms; and 7.96 ms; respectively. The synthesized mixture of hypergolic chemicals could thus be used as a rocket propellant liquid fuel. Full article

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10 pages, 1576 KiB

Open AccessArticle

Local Effects on Lung Parenchyma Using a 600 µm Bare Fiber with the Diode-Pumped Nd:YAG Laser LIMAX^® 120

by Peter Rexin, Detlef Bartsch and Andreas Kirschbaum

Appl. Sci. 2015, 5(4), 1560-1569; https://doi.org/10.3390/app5041560 - 3 Dec 2015

Cited by 2 | Viewed by 5591

Abstract

Lung metastases are frequently removed with an Nd:YAG laser. The aim is to perform a non-anatomic resection of all intraoperatively palpable lung metastases completely in order to preserve the largest possible amount of healthy lung parenchyma. The surgeon can either work with a [...] Read more.

Lung metastases are frequently removed with an Nd:YAG laser. The aim is to perform a non-anatomic resection of all intraoperatively palpable lung metastases completely in order to preserve the largest possible amount of healthy lung parenchyma. The surgeon can either work with a focusing handpiece or use a laser fiber of the so-called bare fiber with direct contact to the lung parenchyma. We currently use a 600 µm bare fiber for applications involving the lung parenchyma. Precise data on the local effect of the laser fiber on the lung parenchyma are not available, especially with regard to an increase in the laser energy. We want to study this question within the scope of an experimental model in pig lungs by means of systematic and reproducible tests. The lung lobes were removed from animals recently slaughtered in the abattoir and taken to the laboratory immediately, where the lobes were stored such that the surface of the lungs was parallel to the floor. A 600 µm bare fiber was attached to a mounting bracket vertically above the lung surface at a distance of either 0, 5, or 10 mm. This mounting bracket was in turn connected to a hydraulic feed motor. The feed motor is capable of moving the bare fiber forward across the lungs consistently at three different speeds (5 mm/s, 10 mm/s, or 20 mm/s). The bare fiber itself was connected to the diode-pumped Nd: YAG Laser LIMAX^® 120 (Gebrüder Martin GmbH & Co KG, Tuttlingen, Germany). We carried out the tests using three different laser powers: 20 W, 60 W, and 120 W. The lung lesions caused by the laser in each of the lungs were resected and sent in for histological analysis. The exact size of the vaporization and coagulation zone was measured using the HE sections, and the respective mean values (with standard deviations) were ascertained. For all laser powers, the extent of the vaporization was greatest with a motion speed of 5 mm/s for the respective laser power: 756.4 ± 1.2 µm (20 W), 1411.0 ± 2.3 µm (60 W) and 2126.0 ± 1.4 µm (120 W). At the same time, the extent of the coagulation zone decreased with a consistent speed: 221.8 ± 2.9 µm (20 W), 324.9 ± 1.8 µm (60 W), and 450.5 ± 1.8 µm (120 W). With a consistent laser energy and increasing speed, we also saw a decrease in the size of the vaporization and of the coagulation zone. The same applies for an increasing distance of the bare fiber to the lung surface. The coagulation effect is the dominant effect here. At an operating speed of 5 mm/s and a maximum laser energy of 120, the 600 µm bare fiber exerts a maximum effect. With an increasing distance of the tip of the bare fiber to the lung surface, the coagulation effect is dominant. The effect of the laser decreases with increasing operating speeds. Full article

(This article belongs to the Special Issue Casting Light on Cancer Therapy)

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13 pages, 2990 KiB

Open AccessArticle

Diode-Pumped High Energy and High Average Power All-Solid-State Picosecond Amplifier Systems

by Jiaxing Liu, Wei Wang, Zhaohua Wang, Zhiguo Lv, Zhiyuan Zhang and Zhiyi Wei

Appl. Sci. 2015, 5(4), 1590-1602; https://doi.org/10.3390/app5041590 - 4 Dec 2015

Cited by 21 | Viewed by 7975

Abstract

We present our research on the high energy picosecond laser operating at a repetition rate of 1 kHz and the high average power picosecond laser running at 100 kHz based on bulk Nd-doped crystals. With diode-pumped solid state (DPSS) hybrid amplifiers consisting of [...] Read more.

We present our research on the high energy picosecond laser operating at a repetition rate of 1 kHz and the high average power picosecond laser running at 100 kHz based on bulk Nd-doped crystals. With diode-pumped solid state (DPSS) hybrid amplifiers consisting of a picosecond oscillator, a regenerative amplifier, end-pumped single-pass amplifiers, and a side-pumped amplifier, an output energy of 64.8 mJ at a repetition rate of 1 kHz was achieved. An average power of 37.5 W at a repetition rate of 100 kHz pumped by continuous wave laser diodes was obtained. Compact, stable and high power DPSS laser amplifier systems with good beam qualities are excellent picosecond sources for high power optical parametric chirped pulse amplification (OPCPA) and high-efficiency laser processing. Full article

(This article belongs to the Special Issue Diode-Pumped, Ultra-Short Pulse Lasers)

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13 pages, 667 KiB

Open AccessArticle

Application of Linear Quadratic Gaussian and Coefficient Diagram Techniques to Distributed Load Frequency Control of Power Systems

by Tarek Hassan Mohamed, Ahmed A. Zaki Diab and Mahmoud M. Hussein

Appl. Sci. 2015, 5(4), 1603-1615; https://doi.org/10.3390/app5041603 - 4 Dec 2015

Cited by 10 | Viewed by 5570

Abstract

This paper presented both the linear quadratic Gaussian technique (LQG) and the coefficient diagram method (CDM) as load frequency controllers in a multi-area power system to deal with the problem of variations in system parameters and load demand change. The full states of [...] Read more.

This paper presented both the linear quadratic Gaussian technique (LQG) and the coefficient diagram method (CDM) as load frequency controllers in a multi-area power system to deal with the problem of variations in system parameters and load demand change. The full states of the system including the area frequency deviation have been estimated using the Kalman filter technique. The efficiency of the proposed control method has been checked using a digital simulation. Simulation results indicated that, with the proposed CDM + LQG technique, the system is robust in the face of parameter uncertainties and load disturbances. A comparison between the proposed technique and other schemes is carried out, confirming the superiority of the proposed CDM + LQG technique. Full article

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23 pages, 861 KiB

Open AccessArticle

Lean-Agile Adaptations in Clinical Laboratory Accredited ISO 15189

by Carlos Vilaplana Pérez, Gloria Soria Guerrero, Federico Garriga Garzón and Angel Salas Garcia

Appl. Sci. 2015, 5(4), 1616-1638; https://doi.org/10.3390/app5041616 - 4 Dec 2015

Cited by 3 | Viewed by 5610

Abstract

It’s introduced Lean techniques in a Clinical Laboratory to improve the operability and the efficiency in continuous processes of analysis, failsafe systems, analysis of areas of value pursuit of zero defects and reduction of waste, and it promote continuous improvement in presented difficulties [...] Read more.

It’s introduced Lean techniques in a Clinical Laboratory to improve the operability and the efficiency in continuous processes of analysis, failsafe systems, analysis of areas of value pursuit of zero defects and reduction of waste, and it promote continuous improvement in presented difficulties in adapting to the changing needs of the healthcare environment. Whereas it is necessary to incorporate certification and accreditation, note that the adaptability of the clinical laboratory to the changing needs of physicians in obtaining analytical information is reduced. The application of an agile methodology on analytical systems can provide a line of work that allows the incorporation of planning short work cycles on equips quickly with operational autonomy on the basis of demand and respecting the accreditation requirements and flexibility to ensure adequate performance as the intercomparison of results from the different units analytics, analytical quality and turnaround times. Between 2012 and 2014, a process of analysis and improvement was applied to circuits, a 5 s system, transportation of samples, inventory of reactive and samples, motion of personal and samples, reductions of waiting and delays, overproduction, over processing, and defects of results and reports. At last it seems necessary to apply the Agile methodology to adapt to the evolving necessities in time and the different origins of the samples. It’s have used modular systems where the modules of this study are programmed with immunoassay techniques and it has reduced the operative modules depending on the required activity, ensuring the goals of turnaround times, analytic quality, service, health care continuity, and keeping up with the ISO 15189 accreditation requirements. The results of applying the concept of Lean-Agile to a modular system allows us to reduce the associated costs to the seasonal variation of the health care demand and to adapt the system to the changes on the pattern of analytic demand. The savings obtained are two laboratory technicians for a month and those derived from deactivating a complete modular section consisting of three analysts. Average turnaround time (TAT) of 99.5% from the analyzed parameters has been kept equal to the one obtained in common conditions with a p < 0.01. The laboratory has maintained the quality goals measured in analytical variability. Prior to that, it most objectified the inter-comparability of the results among the used channels. Full article

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26 pages, 5663 KiB

Open AccessArticle

Magnetohydrodynamic Flow and Heat Transfer of Nanofluids in Stretchable Convergent/Divergent Channels

by Syed Tauseef Mohyud-Din, Umar Khan, Naveed Ahmed and Saleh M. Hassan

Appl. Sci. 2015, 5(4), 1639-1664; https://doi.org/10.3390/app5041639 - 4 Dec 2015

Cited by 92 | Viewed by 7017

Abstract

This article is dedicated to analyzing the heat transfer in the flow of water-based nanofluids in a channel with non-parallel stretchable walls. The magnetohydrodynamic (MHD) nature of the flow is considered. Equations governing the flow are transformed into a system of nonlinear ordinary [...] Read more.

This article is dedicated to analyzing the heat transfer in the flow of water-based nanofluids in a channel with non-parallel stretchable walls. The magnetohydrodynamic (MHD) nature of the flow is considered. Equations governing the flow are transformed into a system of nonlinear ordinary differential equations. The said system is solved by employing two different techniques, the variational iteration method (VIM) and the Runge-Kutta-Fehlberg method (RKF). The influence of the emerging parameters on the velocity and temperature profiles is highlighted with the help of graphs coupled with comprehensive discussions. A comparison with the already existing solutions is also made, which are the special cases of the current problem. It is observed that the temperature profile decreases with an increase in the nanoparticle volume fraction. Furthermore, a magnetic field can be used to control the possible separation caused by the backflows in the case of diverging channels. The effects of parameters on the skin friction coefficient and Nusselt number are also presented using graphical aid. The nanoparticle volume fraction helps to reduce the temperature of the channel and to enhance the rate of heat transfer at the wall. Full article

(This article belongs to the Section Nanotechnology and Applied Nanosciences)

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18 pages, 1900 KiB

Open AccessArticle

Monitoring Techniques of Cerium Stabilized Zirconia for Medical Prosthesis

by Adriana Savin, Mihail-Liviu Craus, Vitalii Turchenko, Alina Bruma, Pierre-Antoine Dubos, Sylvie Malo, Tatiana E. Konstantinova and Valerii V. Burkhovetsky

Appl. Sci. 2015, 5(4), 1665-1682; https://doi.org/10.3390/app5041665 - 8 Dec 2015

Cited by 22 | Viewed by 6068

Abstract

The purpose of this paper is to emphasize the improvement of Zr-based ceramics properties as a function of addition of Ce ions in the structure of the original ceramics. The structural investigations proposed in this paper cover X-ray, and neutron diffraction offered the [...] Read more.

The purpose of this paper is to emphasize the improvement of Zr-based ceramics properties as a function of addition of Ce ions in the structure of the original ceramics. The structural investigations proposed in this paper cover X-ray, and neutron diffraction offered the first indication of the variation of the phase composition and the structural parameters, micro-hardness measurements as well as non-destructive evaluations in order to analyze the structural properties of these materials with utmost importance in fields such as medicine, where these composite materials are used in hip-implants or dental implants/coatings. In combination of Resonant Ultrasound Spectroscopy, which makes use of the resonance frequencies corresponding to the normal vibrational modes of a solid in order to evaluate the elastic constants of the materials, we emphasize a unique approach on evaluating the physical properties of these ceramics, which could help in advancing the understanding of properties and applications in medical fields. Full article

(This article belongs to the Special Issue Acoustic and Elastic Waves: Recent Trends in Science and Engineering)

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16 pages, 2508 KiB

Open AccessArticle

Correlation between Earthquakes and AE Monitoring of Historical Buildings in Seismic Areas

by Giuseppe Lacidogna, Patrizia Cutugno, Gianni Niccolini, Stefano Invernizzi and Alberto Carpinteri

Appl. Sci. 2015, 5(4), 1683-1698; https://doi.org/10.3390/app5041683 - 8 Dec 2015

Cited by 9 | Viewed by 5507

Abstract

In this contribution a new method for evaluating seismic risk in regional areas based on the acoustic emission (AE) technique is proposed. Most earthquakes have precursors, i.e., phenomena of changes in the Earth’s physical-chemical properties that take place prior to an earthquake. [...] Read more.

In this contribution a new method for evaluating seismic risk in regional areas based on the acoustic emission (AE) technique is proposed. Most earthquakes have precursors, i.e., phenomena of changes in the Earth’s physical-chemical properties that take place prior to an earthquake. Acoustic emissions in materials and earthquakes in the Earth’s crust, despite the fact that they take place on very different scales, are very similar phenomena; both are caused by a release of elastic energy from a source located in a medium. For the AE monitoring, two important constructions of Italian cultural heritage are considered: the chapel of the “Sacred Mountain of Varallo” and the “Asinelli Tower” of Bologna. They were monitored during earthquake sequences in their relative areas. By using the Grassberger-Procaccia algorithm, a statistical method of analysis was developed that detects AEs as earthquake precursors or aftershocks. Under certain conditions it was observed that AEs precede earthquakes. These considerations reinforce the idea that the AE monitoring can be considered an effective tool for earthquake risk evaluation. Full article

(This article belongs to the Special Issue Acoustic and Elastic Waves: Recent Trends in Science and Engineering)

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16 pages, 1315 KiB

Open AccessArticle

Feasibility Study of Sensor Aided Impact Acoustic Sorting of Plastic Materials from End-of-Life Vehicles (ELVs)

by Jiu Huang, Zhengfu Bian and Shaogang Lei

Appl. Sci. 2015, 5(4), 1699-1714; https://doi.org/10.3390/app5041699 - 9 Dec 2015

Cited by 7 | Viewed by 4990

Abstract

The purpose of this feasibility research was to study a novel sensor based separation method for recycling of plastic materials from end-of-life vehicles (ELVs) by using eigen-frequency response of impact acoustic emission. In this research three kinds of commonly used plastics, polypropylene (PP), [...] Read more.

The purpose of this feasibility research was to study a novel sensor based separation method for recycling of plastic materials from end-of-life vehicles (ELVs) by using eigen-frequency response of impact acoustic emission. In this research three kinds of commonly used plastics, polypropylene (PP), acrylonitrile-butadiene-styrene (ABS), and styrene-maleic-anhydride (SMA) sampled from end-of-life vehicles, were researched. Almost all the crushed plastic scraps had a flake structure, theoretically their impact response behaviors were determined by their diameters and thicknesses. The equivalent diameters of the scraps were characterized by fine sieving and their thicknesses were measured online by a 3D laser triangulation sensor above the conveying path. Following this the scraps were free dropped one-by-one to impact with an impact passive body on which impact acoustic emission (AE) signals were generated and acquired by an acoustic pickup sensor. Thirdly, the AE signals which carried eigen-frequency response features were processed and characterized. Results demonstrated that the scraps with diameters < 8 mm were too weak for the actual devices to process; the scraps with diameter from 8–13 mm still generated quite a lot of AE signals of inadequate intensity. Finally the general characterization and recognition yields were 64.6%, 61.7%, and 63.9% of PP, ABS, and SMA in mass, respectively of tested materials. Full article

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20 pages, 2840 KiB

Open AccessArticle

Electromagnetic Acoustic Transducers Applied to High Temperature Plates for Potential Use in the Solar Thermal Industry

by Maria Kogia, Liang Cheng, Abbas Mohimi, Vassilios Kappatos, Tat-Hean Gan, Wamadeva Balachandran and Cem Selcuk

Appl. Sci. 2015, 5(4), 1715-1734; https://doi.org/10.3390/app5041715 - 11 Dec 2015

Cited by 18 | Viewed by 6822

Abstract

Concentrated Solar Plants (CSPs) are used in solar thermal industry for collecting and converting sunlight into electricity. Parabolic trough CSPs are the most widely used type of CSP and an absorber tube is an essential part of them. The hostile operating environment of [...] Read more.

Concentrated Solar Plants (CSPs) are used in solar thermal industry for collecting and converting sunlight into electricity. Parabolic trough CSPs are the most widely used type of CSP and an absorber tube is an essential part of them. The hostile operating environment of the absorber tubes, such as high temperatures (400–550 °C), contraction/expansion, and vibrations, may lead them to suffer from creep, thermo-mechanical fatigue, and hot corrosion. Hence, their condition monitoring is of crucial importance and a very challenging task as well. Electromagnetic Acoustic Transducers (EMATs) are a promising, non-contact technology of transducers that has the potential to be used for the inspection of large structures at high temperatures by exciting Guided Waves. In this paper, a study regarding the potential use of EMATs in this application and their performance at high temperature is presented. A Periodic Permanent Magnet (PPM) EMAT with a racetrack coil, designed to excite Shear Horizontal waves (SH₀), has been theoretically and experimentally evaluated at both room and high temperatures. Full article

(This article belongs to the Special Issue Acoustic and Elastic Waves: Recent Trends in Science and Engineering)

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10 pages, 2521 KiB

Open AccessArticle

Optical Simulation of Light Management in CIGS Thin-Film Solar Cells Using Finite Element Method

by Nikola Bednar, Noemi Severino and Nadja Adamovic

Appl. Sci. 2015, 5(4), 1735-1744; https://doi.org/10.3390/app5041735 - 11 Dec 2015

Cited by 22 | Viewed by 7350

Abstract

In this paper we present an optical simulation of light management in Cu(In,Ga)Se₂ thin-film solar cells with reduced absorber layer thickness, with the goal of absorption enhancement in the absorber layer. The light management was achieved by texturing of the substrate layer, [...] Read more.

In this paper we present an optical simulation of light management in Cu(In,Ga)Se₂ thin-film solar cells with reduced absorber layer thickness, with the goal of absorption enhancement in the absorber layer. The light management was achieved by texturing of the substrate layer, and the conformal growth of all the following layers was assumed. Two texturing shapes have been explored: triangular and convex, with different periods and height aspect ratios. The simulations have shown that significant enhancement of absorption within the absorber layer can be achieved using the proposed geometry. The results showed that the triangular textures with small periods (100–200 nm) and high aspect ratios have the most prominent effect on the enhancement of absorption within the absorber layer, although they are difficult to achieve experimentally. Full article

(This article belongs to the Special Issue Selected Papers from the 2nd Spring International School and Workshop of Nanotechnology for the Next Generation High Efficiency Photovoltaics)

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11 pages, 1490 KiB

Open AccessArticle

Enhancement Effects of the Terahertz Near-Field Microscopy

by Jian Huang, Zhongbo Yang, Dongshan Wei, Chunlei Du and Hong-Liang Cui

Appl. Sci. 2015, 5(4), 1745-1755; https://doi.org/10.3390/app5041745 - 11 Dec 2015

Cited by 8 | Viewed by 6125

Abstract

Terahertz near-field detection based and imaging on a nanotip has drawn wide attention following extensive applications of terahertz imaging technologies. Through the local enhanced electric field created by a terahertz nanotip in the near field, it is very likely to attain superior detection [...] Read more.

Terahertz near-field detection based and imaging on a nanotip has drawn wide attention following extensive applications of terahertz imaging technologies. Through the local enhanced electric field created by a terahertz nanotip in the near field, it is very likely to attain superior detection sensitivity and higher spatial resolution. This paper simulates the local enhancement effects of the terahertz near-field microscopy using a two-dimension finite difference time domain (2D-FDTD) method. Factors that influence the enhancement effects are investigated and analyzed in detail. Simulation results show that the size of the nanotip apex, the apex-substrate distance, dielectric properties of the substrate and the detected sample, etc., have significant impacts on the electric field enhancement and spatial resolution of the terahertz near-field nanotip, which can be explained from the effective polarizability of the nanotip-sample/substrate system. Full article

(This article belongs to the Special Issue Frontiers in Terahertz Science and Technology)

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17 pages, 386 KiB

Open AccessArticle

A Modified Feature Selection and Artificial Neural Network-Based Day-Ahead Load Forecasting Model for a Smart Grid

by Ashfaq Ahmad, Nadeem Javaid, Nabil Alrajeh, Zahoor Ali Khan, Umar Qasim and Abid Khan

Appl. Sci. 2015, 5(4), 1756-1772; https://doi.org/10.3390/app5041756 - 11 Dec 2015

Cited by 47 | Viewed by 6314

Abstract

In the operation of a smart grid (SG), day-ahead load forecasting (DLF) is an important task. The SG can enhance the management of its conventional and renewable resources with a more accurate DLF model. However, DLF model development is highly challenging due to [...] Read more.

In the operation of a smart grid (SG), day-ahead load forecasting (DLF) is an important task. The SG can enhance the management of its conventional and renewable resources with a more accurate DLF model. However, DLF model development is highly challenging due to the non-linear characteristics of load time series in SGs. In the literature, DLF models do exist; however, these models trade off between execution time and forecast accuracy. The newly-proposed DLF model will be able to accurately predict the load of the next day with a fair enough execution time. Our proposed model consists of three modules; the data preparation module, feature selection and the forecast module. The first module makes the historical load curve compatible with the feature selection module. The second module removes redundant and irrelevant features from the input data. The third module, which consists of an artificial neural network (ANN), predicts future load on the basis of selected features. Moreover, the forecast module uses a sigmoid function for activation and a multi-variate auto-regressive model for weight updating during the training process. Simulations are conducted in MATLAB to validate the performance of our newly-proposed DLF model in terms of accuracy and execution time. Results show that our proposed modified feature selection and modified ANN (m(FS + ANN))-based model for SGs is able to capture the non-linearity(ies) in the history load curve with 97 . 11 % accuracy. Moreover, this accuracy is achieved at the cost of a fair enough execution time, i.e., we have decreased the average execution time of the existing FS + ANN-based model by 38 . 50 % . Full article

(This article belongs to the Special Issue Applied Artificial Neural Network)

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17 pages, 324 KiB

Open AccessArticle

On the Design of an Elegant CFO Estimate System with the Assistance of Pilots for OFDM Transmission

by Tsui-Tsai Lin and Fuh-Hsin Hwang

Appl. Sci. 2015, 5(4), 1773-1789; https://doi.org/10.3390/app5041773 - 12 Dec 2015

Cited by 1 | Viewed by 3944

Abstract

We present an improved line search method of the carrier frequency offset (CFO) estimate technique for OFDM systems aided with pilots. Unlike the conventional approaches, prior knowledge of channel order is unnecessary for the presented scheme, because we apply an interpolation technique for [...] Read more.

We present an improved line search method of the carrier frequency offset (CFO) estimate technique for OFDM systems aided with pilots. Unlike the conventional approaches, prior knowledge of channel order is unnecessary for the presented scheme, because we apply an interpolation technique for obtaining the extended channel frequency response. The search mechanism of the proposed approach is primarily based on the criterion that CFO can be found by discovering the frequency that achieves the minimum value of the well-defined channel residual energy. In addition, we substitute the line search method with an iterative approach to reduce the proposed estimator’s complexity. Analytical and simulation results have been conducted to verify the efficacy of the proposed schemes in this paper. Full article

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13 pages, 3035 KiB

Open AccessArticle

Temporal Shaping of High Peak Power Pulse Trains from a Burst-Mode Laser System

by Jörg Körner, Jürgen Reiter, Joachim Hein and Malte C. Kaluza

Appl. Sci. 2015, 5(4), 1790-1802; https://doi.org/10.3390/app5041790 - 15 Dec 2015

Cited by 6 | Viewed by 5985

Abstract

It has been shown in the past that pulsed laser systems operating in the so-called “burst mode” are a beneficial approach to generate high peak power laser pulses at high repetition rates suitable for various applications. So far, most high-energy burst-mode laser systems [...] Read more.

It has been shown in the past that pulsed laser systems operating in the so-called “burst mode” are a beneficial approach to generate high peak power laser pulses at high repetition rates suitable for various applications. So far, most high-energy burst-mode laser systems put great effort into generating a homogeneous energy distribution across the burst duration, e.g., by shaping the pump pulse. In this work, we present a new shaping technique, which is able to produce arbitrary energy distributions within the burst by pre-shaping the seed pulse burst with a Pockels cell. Furthermore, this technique allows for the precompensation of any static modulations across the burst, which may be introduced during the subsequent amplification process. Therefore, a pulse burst with a uniform energy distribution can also be generated. The method is tested with an ultra-short pulse burst mode laser amplifier system producing bursts of a 1 ms duration with a pulse repetition rate of 1 MHz and a maximum output power of 800 W during the burst. Furthermore, a method to predict the influence of the amplifier on a non-uniformly shaped burst is presented and successfully tested to produce a pre-defined pulse shape after amplification. Full article

(This article belongs to the Special Issue Diode-Pumped, Ultra-Short Pulse Lasers)

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9 pages, 826 KiB

Open AccessArticle

High Power Diode-Side-Pumped Q-Switched Nd:YAG Solid-State Laser with a Thermoelectric Cooler

by Jian Dong, Xue-Sheng Liu, Chao Peng, You-Qiang Liu and Zhi-Yong Wang

Appl. Sci. 2015, 5(4), 1837-1845; https://doi.org/10.3390/app5041837 - 16 Dec 2015

Cited by 17 | Viewed by 7774

Abstract

A diode-side-pumped, high-energy, high-beam-quality, pulsed solid-state Nd³⁺:Y₃Al₅O₁₂ (Nd:YAG) laser with a thermoelectric cooler (TEC) is investigated in this study. The pump laser was a pulsed laser diode array with maximum peak power of 15 kW. A [...] Read more.

A diode-side-pumped, high-energy, high-beam-quality, pulsed solid-state Nd³⁺:Y₃Al₅O₁₂ (Nd:YAG) laser with a thermoelectric cooler (TEC) is investigated in this study. The pump laser was a pulsed laser diode array with maximum peak power of 15 kW. A 350 mJ laser pulse was obtained with a wavelength of 1064 nm, a pulse duration of 10 ns, a total electrical-to-optical efficiency of 7.5%, a relative stability of output energy of 5%, and a beam quality of M² < 4. Full article

(This article belongs to the Special Issue Diode-Pumped, Ultra-Short Pulse Lasers)

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23 pages, 5381 KiB

Open AccessArticle

Numerical Simulation of Laminar Forced Convection of Pin-Fin Heat-Sink Array in a Channel by Using Porous Approach

by Tzer-Ming Jeng and Sheng-Chung Tzeng

Appl. Sci. 2015, 5(4), 1846-1868; https://doi.org/10.3390/app5041846 - 16 Dec 2015

Cited by 10 | Viewed by 8385

Abstract

This work used a porous approach model to numerically investigate the fluid flow and heat transfer characteristics of the pin-fin heat-sink array in a rectangular channel with in-line arrangement. The air flow through the channel was laminar. The pin-fin heat sinks with various [...] Read more.

This work used a porous approach model to numerically investigate the fluid flow and heat transfer characteristics of the pin-fin heat-sink array in a rectangular channel with in-line arrangement. The air flow through the channel was laminar. The pin-fin heat sinks with various porosities and pin-fin numbers were employed. The relative center-to-center longitudinal and transverse distances between adjacent heat sinks were changed. The results indicate that the Nusselt number of various heat-sink arrays increased with decreasing the relative center-to-center transverse distance, but not varied with the relative center-to-center longitudinal distance. For the typical pin-fin heat-sink arrays, the Nusselt number changed slightly for the heat sinks with 0.358–0.556 porosity, but increased by 11.7%–24.8% when the porosity increased from 0.556 to 0.750, and then dropped obviously when the porosity exceeded 0.750. Increasing the number of pin fins continuously could increase Nusselt number. However, when the number of pin fins was large, the Nusselt number increased with the number of pin fins slowly. The present numerical simulation has been validated by the typical experiment. Finally, a semi-empirical correlation of Nusselt number for each heat sink in the heat-sink array was proposed. Full article

(This article belongs to the Special Issue Intelligence Computational and Control Approaches for Multi-Physic Coupling Engineering Systems)

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13 pages, 5187 KiB

Open AccessArticle

Kinetic Adsorption Study of Silver Nanoparticles on Natural Zeolite: Experimental and Theoretical Models

by Alvaro Ruíz-Baltazar and Ramiro Pérez

Appl. Sci. 2015, 5(4), 1869-1881; https://doi.org/10.3390/app5041869 - 16 Dec 2015

Cited by 20 | Viewed by 6902

Abstract

In this research, the adsorption capacity of Ag nanoparticles on natural zeolite from Oaxaca is presented. In order to describe the adsorption mechanism of silver nanoparticles on zeolite, experimental adsorption models for Ag ions and Ag nanoparticles were carried out. These experimental data [...] Read more.

In this research, the adsorption capacity of Ag nanoparticles on natural zeolite from Oaxaca is presented. In order to describe the adsorption mechanism of silver nanoparticles on zeolite, experimental adsorption models for Ag ions and Ag nanoparticles were carried out. These experimental data obtained by the atomic absorption spectrophotometry technique were compared with theoretical models such as Lagergren first-order, pseudo-second-order, Elovich, and intraparticle diffusion. Correlation factors R² of the order of 0.99 were observed. Analysis by transmission electron microscopy describes the distribution of the silver nanoparticles on the zeolite outer surface. Additionally, a chemical characterization of the material was carried out through a dilution process with lithium metaborate. An average value of 9.3 in the Si/Al ratio was observed. Factors such as the adsorption behavior of the silver ions and the Si/Al ratio of the zeolite are very important to support the theoretical models and establish the adsorption mechanism of Ag nanoparticles on natural zeolite. Full article

(This article belongs to the Section Nanotechnology and Applied Nanosciences)

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22 pages, 2894 KiB

Open AccessArticle

Design and Implementation of an IoT Access Point for Smart Home

by Chih-Yung Chang, Chin-Hwa Kuo, Jian-Cheng Chen and Tzu-Chia Wang

Appl. Sci. 2015, 5(4), 1882-1903; https://doi.org/10.3390/app5041882 - 16 Dec 2015

Cited by 47 | Viewed by 12353

Abstract

Network communication and micro-electro-mechanical embedded technologies have attracted much attention in recent years. Through these technologies, the capabilities of sensing, identification, and communication can be embedded in various smart devices. These smart devices can automatically connect to the Internet and form an intelligent [...] Read more.

Network communication and micro-electro-mechanical embedded technologies have attracted much attention in recent years. Through these technologies, the capabilities of sensing, identification, and communication can be embedded in various smart devices. These smart devices can automatically connect to the Internet and form an intelligent network called Internet of Things (IoT). However, these devices are embedded with different wireless communication interfaces such as Wi-Fi and ZigBee. This paper presents the design and implementation of an IoT access point that supports functionalities of coordination of various wireless transmission protocols. Based on the existing Wi-Fi access point, we have embedded a ZigBee module and implemented ZigBee and UPnP protocols into the designed IoT access point, which supports ZigBee communication capabilities over the Internet. Full article

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18 pages, 1983 KiB

Open AccessArticle

Thermal Lattice Boltzmann Simulation of Entropy Generation within a Square Enclosure for Sensible and Latent Heat Transfers

by Alissar Yehya and Hassane Naji

Appl. Sci. 2015, 5(4), 1904-1921; https://doi.org/10.3390/app5041904 - 17 Dec 2015

Cited by 10 | Viewed by 4816

Abstract

This paper deals with the numerical simulation of heat transfer and entropy generation in a 2D square enclosure for convective melting. A thermal lattice Boltzmann method (TLBM) is used to handle the study, which has been conducted for Prandtl numbers from 0.02 to [...] Read more.

This paper deals with the numerical simulation of heat transfer and entropy generation in a 2D square enclosure for convective melting. A thermal lattice Boltzmann method (TLBM) is used to handle the study, which has been conducted for Prandtl numbers from 0.02 to 70 at Rayleigh numbers of 10⁴ and 10⁵. The results are presented in terms of the total entropy generation, average Bejan number and average Nusselt number. Within the range considered for the key parameters, the entropy generation is found to be controlled by the heat transfer loss for low Prandtl numbers. However, for the large Prandtl numbers, its variation is dominated by shearing losses. Moreover, the presence of the latent heat state decreases the overall thermodynamic losses while increasing the quantity of heat transferred. Full article

(This article belongs to the Special Issue Phase Change Materials (PCM))

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20 pages, 726 KiB

Open AccessArticle

Self-Seeded RSOA-Fiber Cavity Lasers vs. ASE Spectrum-Sliced or Externally Seeded Transmitters—A Comparative Study

by Simon A. Gebrewold, Romain Bonjour, Sophie Barbet, Anaelle Maho, Romain Brenot, Philippe Chanclou, Marco Brunero, Lucia Marazzi, Paola Parolari, Angelina Totovic, Dejan Gvozdic, David Hillerkuss, Christian Hafner and Juerg Leuthold

Appl. Sci. 2015, 5(4), 1922-1941; https://doi.org/10.3390/app5041922 - 17 Dec 2015

Cited by 8 | Viewed by 6924

Abstract

Reflective semiconductor optical amplifier fiber cavity lasers (RSOA-FCLs) are appealing, colorless, self-seeded, self-tuning and cost-efficient upstream transmitters. They are of interest for wavelength division multiplexed passive optical networks (WDM-PONs) based links. In this paper, we compare RSOA-FCLs with alternative colorless sources, namely the [...] Read more.

Reflective semiconductor optical amplifier fiber cavity lasers (RSOA-FCLs) are appealing, colorless, self-seeded, self-tuning and cost-efficient upstream transmitters. They are of interest for wavelength division multiplexed passive optical networks (WDM-PONs) based links. In this paper, we compare RSOA-FCLs with alternative colorless sources, namely the amplified spontaneous emission (ASE) spectrum-sliced and the externally seeded RSOAs. We compare the differences in output power, signal-to-noise ratio (SNR), relative intensity noise (RIN), frequency response and transmission characteristics of these three sources. It is shown that an RSOA-FCL offers a higher output power over an ASE spectrum-sliced source with SNR, RIN and frequency response characteristics halfway between an ASE spectrum-sliced and a more expensive externally seeded RSOA. The results show that the RSOA-FCL is a cost-efficient WDM-PON upstream source, borrowing simplicity and cost-efficiency from ASE spectrum slicing with characteristics that are, in many instances, good enough to perform short-haul transmission. To substantiate our statement and to quantitatively compare the potential of the three schemes, we perform data transmission experiments at 5 and 10 Gbit/s. Full article

(This article belongs to the Special Issue Fibre Lasers: From Underlying Science and Technology to Applications)

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13 pages, 2689 KiB

Open AccessArticle

A Novel Piezoelectric Energy Harvester Using the Macro Fiber Composite Cantilever with a Bicylinder in Water

by Rujun Song, Xiaobiao Shan, Fengchi Lv, Jinzhe Li and Tao Xie

Appl. Sci. 2015, 5(4), 1942-1954; https://doi.org/10.3390/app5041942 - 17 Dec 2015

Cited by 68 | Viewed by 9726

Abstract

A novel piezoelectric energy harvester equipped with two piezoelectric beams and two cylinders was proposed in this work. The energy harvester can convert the kinetic energy of water into electrical energy by means of vortex-induced vibration (VIV) and wake-induced vibration (WIV). The effects [...] Read more.

A novel piezoelectric energy harvester equipped with two piezoelectric beams and two cylinders was proposed in this work. The energy harvester can convert the kinetic energy of water into electrical energy by means of vortex-induced vibration (VIV) and wake-induced vibration (WIV). The effects of load resistance, water velocity and cylinder diameter on the performance of the harvester were investigated. It was found that the vibration of the upstream cylinder was VIV which enhanced the energy harvesting capacity of the upstream piezoelectric beam. As for the downstream cylinder, both VIV and the WIV could be obtained. The VIV was found with small L/D, e.g., 2.125, 2.28, 2.5, and 2.8. Additionally, the WIV was stimulated with the increase of L/D (such as 3.25, 4, and 5.5). Due to the WIV, the downstream beam presented better performance in energy harvesting with the increase of water velocity. Furthermore, it revealed that more electrical energy could be obtained by appropriately matching the resistance and the diameter of the cylinder. With optimal resistance (170 kΩ) and diameter of the cylinder (30 mm), the maximum output power of 21.86 μW (sum of both piezoelectric beams) was obtained at a water velocity of 0.31 m/s. Full article

(This article belongs to the Special Issue Ferroelectric Ceramics)

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15 pages, 801 KiB

Open AccessArticle

Main Leaf Polyphenolic Components of Berry Color Variant Grapevines and Their Acclimative Responses to Sunlight Exposure

by Marianna Kocsis, László Abrankó, Ferhan Ayaydin, Kristóf Csepregi, Nóra Papp, Péter Teszlák and Gábor Jakab

Appl. Sci. 2015, 5(4), 1955-1969; https://doi.org/10.3390/app5041955 - 18 Dec 2015

Cited by 7 | Viewed by 5733

Abstract

Grapevine leaf synthesizes a wide variety of bioactive secondary metabolites, including polyphenols, which are also key components in ensuring development and growth of the whole plant even under adverse environmental conditions. Our study evaluates the nonanthocyanin polyphenolic composition in grapevine leaves of three [...] Read more.

Grapevine leaf synthesizes a wide variety of bioactive secondary metabolites, including polyphenols, which are also key components in ensuring development and growth of the whole plant even under adverse environmental conditions. Our study evaluates the nonanthocyanin polyphenolic composition in grapevine leaves of three varieties of Gohér conculta (Vitis vinifera L.) native to Hungary. A high performance liquid chromatography (HPLC) system including a diode array detector (DAD) coupled to a time-of-flight mass spectrometer (q-TOFMS) was successfully applied to profile intact glycoconjugate forms in samples. In-source fragmentation was utilized in order to provide structural information on the compounds. Using this method, the presence of 16 polyphenolic metabolites were confirmed, and eight of them were subjected to further quantification in sun acclimated and half shaded leaves. Intracellular microimaging detected accumulation of flavonols in cell nuclei, cell wall and chloroplasts. Our findings demonstrated that Gohér conculta—a special grapevine taxon of our viticultural heritage with berry color variants—is a suitable model to study the interaction between genetic and environmental factors in determination of grapevine phenolic composition. Full article

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10 pages, 4690 KiB

Open AccessFeature PaperArticle

Generation of 25-TW Femtosecond Laser Pulses at 515 nm with Extremely High Temporal Contrast

by Marco Hornung, Georg Alexander Becker, Andreas Seidel, Jan Reislöhner, Hartmut Liebetrau, Lennart Bock, Sebastian Keppler, Alexander Kessler, Matthew Zepf, Joachim Hein and Malte Christoph Kaluza

Appl. Sci. 2015, 5(4), 1970-1979; https://doi.org/10.3390/app5041970 - 19 Dec 2015

Cited by 11 | Viewed by 7063

Abstract

We report on the frequency doubling of femtosecond laser pulses at 1030 nm center wavelength generated from the fully diode-pumped laser system POLARIS. The newly generated pulses at a center wavelength of 515 nm have a pulse energy of 3 J with a [...] Read more.

We report on the frequency doubling of femtosecond laser pulses at 1030 nm center wavelength generated from the fully diode-pumped laser system POLARIS. The newly generated pulses at a center wavelength of 515 nm have a pulse energy of 3 J with a pulse duration of 120 fs. On the basis of initially ultra-high contrast seed pulses we expect a temporal intensity contrast better 10 17 200 ps before the peak of the main pulse. We analyzed the temporal intensity contrast from milliseconds to femtoseconds with a dynamic range covering more than 20 orders of magnitude. The pulses were focussed with a f/2-focussing parabola resulting in a peak intensity exceeding 10 20 W / cm 2 . The peak power and intensity are to the best of our knowledge the highest values for 515 nm-laser-pulses achieved so far. Full article

(This article belongs to the Special Issue Diode-Pumped, Ultra-Short Pulse Lasers)

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12 pages, 13682 KiB

Open AccessArticle

Image Hiding Scheme Based on the Atrial Fibrillation Model

by Martynas Vaidelys, Jurate Ragulskiene, Pranas Ziaukas and Minvydas Ragulskis

Appl. Sci. 2015, 5(4), 1980-1991; https://doi.org/10.3390/app5041980 - 21 Dec 2015

Cited by 4 | Viewed by 5972

Abstract

An image communication scheme based on the atrial fibrillation (AF) model is presented in this paper. Self-organizing patterns produced by the AF model are used to hide and transmit secret visual information. A secret image is encoded into the random matrix of initial [...] Read more.

An image communication scheme based on the atrial fibrillation (AF) model is presented in this paper. Self-organizing patterns produced by the AF model are used to hide and transmit secret visual information. A secret image is encoded into the random matrix of initial cell excitation states in the form of a dot-skeleton representation. Self-organized patterns produced by such initial cell states ensure a secure and efficient transmission of secret visual images. Procedures for digital encoding and decoding of secret images, as well as the sensitivity of the communication scheme to the perturbation of the AF model’s parameters are discussed in the paper. Full article

(This article belongs to the Special Issue Intelligence Computational and Control Approaches for Multi-Physic Coupling Engineering Systems)

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17 pages, 2487 KiB

Open AccessArticle

Improved Permeate Flux of PVDF Ultrafiltration Membrane Containing PVDF-g-PHEA Synthesized via ATRP

by Kwang-Mo Kim, Sahng Hyuck Woo, Ju Sung Lee, Hyun Sic Park, Jinwon Park and Byoung Ryul Min

Appl. Sci. 2015, 5(4), 1992-2008; https://doi.org/10.3390/app5041992 - 21 Dec 2015

Cited by 19 | Viewed by 8432

Abstract

Polyvinylidene fluoride (PVDF) ultrafiltration (UF) membrane combined with polyvinylidene fluoride-graft-2-hydroxyethyl acrylate (PVDF-g-PHEA) was fabricated via non-solvent induced phase separation (NIPS). In this study, PVDF-g-PHEA was synthesized via atom transfer radical polymerization (ATRP) method, and then synthesized graft copolymer was characterized using Fourier transform [...] Read more.

Polyvinylidene fluoride (PVDF) ultrafiltration (UF) membrane combined with polyvinylidene fluoride-graft-2-hydroxyethyl acrylate (PVDF-g-PHEA) was fabricated via non-solvent induced phase separation (NIPS). In this study, PVDF-g-PHEA was synthesized via atom transfer radical polymerization (ATRP) method, and then synthesized graft copolymer was characterized using Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and thermogravimetry analysis (TGA). Moreover, PVDF membranes containing graft copolymer (PVDF-g-PHEA) showed lower water contact angle value than pristine PVDF membranes. Macrovoid holes were also observed in cross sectional scanning electron microscope (SEM) image of PVDF membrane containing PVDF-g-PHEA. Accordingly, it was confirmed that these characteristics led PVDF membrane blended with graft copolymer has high final permeate flux and normalized flux compared to pristine PVDF membrane. Full article

(This article belongs to the Special Issue Organo-Fluorine Chemical Science)

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Review

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29 pages, 8301 KiB

Open AccessReview

Status of the High Average Power Diode-Pumped Solid State Laser Development at HiLASE

by Ondřej Novák, Taisuke Miura, Martin Smrž, Michal Chyla, Siva Sankar Nagisetty, Jiří Mužík, Jens Linnemann, Hana Turčičová, Venkatesan Jambunathan, Ondřej Slezák, Magdalena Sawicka-Chyla, Jan Pilař, Stefano Bonora, Martin Divoký, Jakub Měsíček, Alina Pranovich, Pawel Sikocinski, Jaroslav Huynh, Patricie Severová, Petr Navrátil, David Vojna, Lucie Horáčková, Klaus Mann, Antonio Lucianetti, Akira Endo, Danijela Rostohar and Tomáš Mocek Show full author list Hide full author list

Appl. Sci. 2015, 5(4), 637-665; https://doi.org/10.3390/app5040637 - 25 Sep 2015

Cited by 82 | Viewed by 13532

Abstract

An overview of the latest developments of kilowatt-level diode pumped solid state lasers for advanced applications at the HiLASE Centre is presented. An overview of subcontracted and in-house-developed laser beamlines is presented. The aim of development is to build kW-class beamlines delivering picosecond [...] Read more.

An overview of the latest developments of kilowatt-level diode pumped solid state lasers for advanced applications at the HiLASE Centre is presented. An overview of subcontracted and in-house-developed laser beamlines is presented. The aim of development is to build kW-class beamlines delivering picosecond pulses between 1- and 100-kHz repetition rates and high-energy nanosecond pulses at 10 Hz. The picosecond beamlines are based on Yb:YAG thin-disk amplifiers and chirped pulse amplification. The current status of the beamlines’ performance is reported. The advantages of zero-phonon line and pulsed pumping are demonstrated with respect to efficiency, thin disk temperature and beam quality. New diagnostics methods supporting the high average power lasers’ development, such as the high-resolution spectroscopy of Yb-doped materials, in situ thin disk deformation measurements, single-shot M² measurement, realization of wavefront correction by a deformable mirror and the laser performance of a new mixed garnet ceramics, are described. The energetic, thermal and fluid-mechanical numerical modeling for the optimization of the multi-slab amplifiers is also described. Full article

(This article belongs to the Special Issue Diode-Pumped, Ultra-Short Pulse Lasers)

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30 pages, 1737 KiB

Open AccessReview

Carrier-Envelope Offset Stabilized Ultrafast Diode-Pumped Solid-State Lasers

by Stéphane Schilt and Thomas Südmeyer

Appl. Sci. 2015, 5(4), 787-816; https://doi.org/10.3390/app5040787 - 14 Oct 2015

Cited by 23 | Viewed by 10651

Abstract

Optical frequency combs have been revolutionizing many research areas and are finding a growing number of real-world applications. While initially dominated by Ti:Sapphire and fiber lasers, optical frequency combs from modelocked diode-pumped solid-state lasers (DPSSLs) have become an attractive alternative with state-of-the-art performance. [...] Read more.

Optical frequency combs have been revolutionizing many research areas and are finding a growing number of real-world applications. While initially dominated by Ti:Sapphire and fiber lasers, optical frequency combs from modelocked diode-pumped solid-state lasers (DPSSLs) have become an attractive alternative with state-of-the-art performance. In this article, we review the main achievements in ultrafast DPSSLs for frequency combs. We present the current status of carrier-envelope offset (CEO) frequency-stabilized DPSSLs based on various approaches and operating in different wavelength regimes. Feedback to the pump current provides a reliable scheme for frequency comb CEO stabilization, but also other methods with faster feedback not limited by the lifetime of the gain material have been applied. Pumping DPSSLs with high power multi-transverse-mode diodes enabled a new class of high power oscillators and gigahertz repetition rate lasers, which were initially not believed to be suitable for CEO stabilization due to the pump noise. However, this challenge has been overcome, and recently both high power and gigahertz DPSSL combs have been demonstrated. Thin disk lasers have demonstrated the highest pulse energy and average power emitted from any ultrafast oscillator and present a high potential for the future generation of stabilized frequency combs with hundreds of watts average output power. Full article

(This article belongs to the Special Issue Diode-Pumped, Ultra-Short Pulse Lasers)

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12 pages, 682 KiB

Open AccessReview

Chitosan as a Natural Polymer for Heterogeneous Catalysts Support: A Short Review on Its Applications

by Mengshan Lee, Bo-Yen Chen and Walter Den

Appl. Sci. 2015, 5(4), 1272-1283; https://doi.org/10.3390/app5041272 - 17 Nov 2015

Cited by 130 | Viewed by 9338

Abstract

Chitosan, a bio-based polymer which has similar characteristics to those of cellulose, exhibits cationic behavior in acidic solutions and strong affinity for metals ions. Thus, it has received increased attention for the preparation of heterogeneous catalysts. Recent studies demonstrated that chitosan-based catalysts had [...] Read more.

Chitosan, a bio-based polymer which has similar characteristics to those of cellulose, exhibits cationic behavior in acidic solutions and strong affinity for metals ions. Thus, it has received increased attention for the preparation of heterogeneous catalysts. Recent studies demonstrated that chitosan-based catalysts had high sorption capacities, chelating activities, stability and versatility, which could be potentially applied as green reactants in various scientific and engineering applications. This study intends to review the recent development of chitosan-based catalysts, particularly in the aspects of the main mechanisms for preparing the materials and their applications in environmental green chemistry. Studies on the preparation of catalyst nanoparticles/nanospheres supported on chitosan were also reviewed. Full article

(This article belongs to the Special Issue Nano-Catalysts and Their Applications)

26 pages, 2260 KiB

Open AccessReview

New Trends in Dental Biomechanics with Photonics Technologies

by Lídia Carvalho, Paulo Roriz, José Simões and Orlando Frazão

Appl. Sci. 2015, 5(4), 1350-1378; https://doi.org/10.3390/app5041350 - 24 Nov 2015

Cited by 15 | Viewed by 9304

Abstract

Engineering techniques used to evaluate strain-stress fields, materials’ mechanical properties, and load transfer mechanisms, among others, are useful tools in the study of biomechanical applications. These engineering tools, as experimental and numerical ones, were imported to biomechanics, in particular in dental biomechanics, a [...] Read more.

Engineering techniques used to evaluate strain-stress fields, materials’ mechanical properties, and load transfer mechanisms, among others, are useful tools in the study of biomechanical applications. These engineering tools, as experimental and numerical ones, were imported to biomechanics, in particular in dental biomechanics, a few decades ago. Several experimental techniques have been used in dental biomechanics, like photoelasticity, ESPI (Electronic Speckle Pattern Interferometry), strain gages, and other kinds of transducers. However, these techniques have some limitations. For instance, photoelasticity and ESPI give the overall field pattern of the strain, showing the stress-strain concentration points. These methods cannot give an accurate measurement at all points. On the contrary, strain gages can be used to perform local measurements. However, as they use electrical resistances, their use is limited to perform in vivo measurements. Optical fiber sensors have already been used in dentistry, for diagnostic and therapeutic purposes, and in dental biomechanics studies. Lasers have also been used in clinical dentistry for a few decades. Other optical technologies, like optical coherence tomography (OCT), became suitable for dental practice and nowadays it is perhaps one that has had more development in dentristry, along with lasers. Full article

(This article belongs to the Special Issue Feature Papers)

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17 pages, 1869 KiB

Open AccessReview

2D Saturable Absorbers for Fibre Lasers

by Robert I. Woodward and Edmund J. R. Kelleher

Appl. Sci. 2015, 5(4), 1440-1456; https://doi.org/10.3390/app5041440 - 30 Nov 2015

Cited by 247 | Viewed by 13376

Abstract

Two-dimensional (2D) nanomaterials are an emergent and promising platform for future photonic and optoelectronic applications. Here, we review recent progress demonstrating the application of 2D nanomaterials as versatile, wideband saturable absorbers for Q-switching and mode-locking fibre lasers. We focus specifically on the family [...] Read more.

Two-dimensional (2D) nanomaterials are an emergent and promising platform for future photonic and optoelectronic applications. Here, we review recent progress demonstrating the application of 2D nanomaterials as versatile, wideband saturable absorbers for Q-switching and mode-locking fibre lasers. We focus specifically on the family of few-layer transition metal dichalcogenides, including MoS₂, MoSe₂ and WS₂. Full article

(This article belongs to the Special Issue Fibre Lasers: From Underlying Science and Technology to Applications)

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20 pages, 2629 KiB

Open AccessReview

Irregular Homogeneity Domains in Ternary Intermetallic Systems

by Jean-Marc Joubert, Mohamed Andasmas and Jean-Claude Crivello

Appl. Sci. 2015, 5(4), 1570-1589; https://doi.org/10.3390/app5041570 - 4 Dec 2015

Cited by 10 | Viewed by 5968

Abstract

Ternary intermetallic A–B–C systems sometimes have unexpected behaviors. The present paper examines situations in which there is a tendency to simultaneously form the compounds AB_x, AC_x and BC_x with the same crystal structure. This causes irregular shapes of the [...] Read more.

Ternary intermetallic A–B–C systems sometimes have unexpected behaviors. The present paper examines situations in which there is a tendency to simultaneously form the compounds AB_x, AC_x and BC_x with the same crystal structure. This causes irregular shapes of the phase homogeneity domains and, from a structural point of view, a complete reversal of site occupancies for the B atom when crossing the homogeneity domain. This work reviews previous studies done in the systems Fe–Nb–Zr, Hf–Mo–Re, Hf–Re–W, Mo–Re–Zr, Re–W–Zr, Cr–Mn–Si, Cr–Mo–Re, and Mo–Ni–Re, and involving the topologically close-packed Laves, χ and σ phases. These systems have been studied using ternary isothermal section determination, DFT calculations, site occupancy measurement using joint X-ray, and neutron diffraction Rietveld refinement. Conclusions are drawn concerning this phenomenon. The paper also reports new experimental or calculated data on Co–Cr–Re and Fe–Nb–Zr systems. Full article

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34 pages, 1618 KiB

Open AccessReview

Sequentially Palladium-Catalyzed Processes in One-Pot Syntheses of Heterocycles

by Timo Lessing and Thomas J. J. Müller

Appl. Sci. 2015, 5(4), 1803-1836; https://doi.org/10.3390/app5041803 - 16 Dec 2015

Cited by 42 | Viewed by 8654

Abstract

Sequentially Pd-catalyzed processes are excellent entries to heterocycle synthesis. The broad mechanistic variety combined with often very mild reaction conditions allow the concatenation of elementary organic and organometallic steps to novel sequences in the sense of one-pot domino and multicomponent reactions. Given the [...] Read more.

Sequentially Pd-catalyzed processes are excellent entries to heterocycle synthesis. The broad mechanistic variety combined with often very mild reaction conditions allow the concatenation of elementary organic and organometallic steps to novel sequences in the sense of one-pot domino and multicomponent reactions. Given the numerous opportunities of alkyne coordination and their Pd-mediated transformations, alkynylation and carbometallation play a key role, both for purely organometallic sequences as well as in those processes that are intercepted by cyclocondensation. Pd-catalyzed aminations also find more and more entry into novel heterocycle syntheses based upon this theme. Full article

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Appl. Sci., Volume 5, Issue 4 (December 2015) – 83 articles , Pages 637-2008

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