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Selected Papers from ICASI 2015
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Selected Papers from ICASI 2015

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: closed (31 August 2015) | Viewed by 160146

Special Issue Editors

Prof. Dr. Teen­-Hang Meen

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Guest Editor
Department of Electronic Engineering National Formosa University, Yunlin 632, Taiwan
Interests: IOT devices; photovoltaic devices; STEM education
Special Issues, Collections and Topics in MDPI journals
Dr. Stephen D. Prior

E-Mail Website
Guest Editor
Aeronautics, Astronautics and Computational Engineering, University of Southampton, Southampton SO16 7QF, UK
Interests: microsystem design; nanotechnology
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Artde Donald Kin-Tak Lam

E-Mail
Guest Editor
College of Physics and Information Engineering Fuzhou University, Fuzhou, Fujian, China

Special Issue Information

Dear Colleagues,

The 2015 International Conference on Applied System Innovation (ICASI 2015) will be held in Japan on May 22­­–26, 2015, and will provide a unified communication platform for researchers in a wide range of topics. Scientists all over the world actively want to discover new advanced materials in electrical and mechanical engineering. In recent years, the application of advanced materials has been a highly developing field, in the areas of semiconductor and electronic device technology, design, manufacturing, physics, and modeling. Therefore, the field of electrical and mechanical materials has been a subject of review. The scope of ICASI 2015 not only encompasses material sizes at the nanoscale, but also in various dimensions where the onset of size-dependent phenomena usually enables novel applications.

This Special Issue selects excellent papers from ICASI 2015 and covers a very broad scope, including fundamental and advanced materials of electrical and mechanical engineering, their synthesis, engineering their application properties based on optical, electrochemical, magnetic, acoustic, and thermal transduction, their integration with many elements, designing of electrical or mechanical devices, evaluation various performance and exploring their broad applications in industry, environmental control, material analysis, etc. We invite investigators to contribute original research articles, as well as review articles, to this Special Issue. Potential topics include, but are not limited to:

•   Recent developments in fundamental and advanced materials with new electrical and optical properties

•   Nanomaterials for preparation and applications

•   Computational analysis for materials and structures

•   Combinatorial methods for mechanical design and optimization

•   Mechanical applications in advanced materials

Prof. Dr. Teen-Hang Meen
Dr. Stephen D. Prior
Prof. Dr. Artde Donald Kin-Tak Lam
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.


Published Papers (24 papers)

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Research

4651 KiB  
Article
Prediction Surface Morphology of Nanostructure Fabricated by Nano-Oxidation Technology
by Jen-Ching Huang, Ho Chang, Chin-Guo Kuo, Jeen-Fong Li and Yong-Chin You
Materials 2015, 8(12), 8437-8451; https://doi.org/10.3390/ma8125468 - 04 Dec 2015
Cited by 1 | Viewed by 4835
Abstract
Atomic force microscopy (AFM) was used for visualization of a nano-oxidation technique performed on diamond-like carbon (DLC) thin film. Experiments of the nano-oxidation technique of the DLC thin film include those on nano-oxidation points and nano-oxidation lines. The feature sizes of the DLC [...] Read more.
Atomic force microscopy (AFM) was used for visualization of a nano-oxidation technique performed on diamond-like carbon (DLC) thin film. Experiments of the nano-oxidation technique of the DLC thin film include those on nano-oxidation points and nano-oxidation lines. The feature sizes of the DLC thin film, including surface morphology, depth, and width, were explored after application of a nano-oxidation technique to the DLC thin film under different process parameters. A databank for process parameters and feature sizes of thin films was then established, and multiple regression analysis (MRA) and a back-propagation neural network (BPN) were used to carry out the algorithm. The algorithmic results are compared with the feature sizes acquired from experiments, thus obtaining a prediction model of the nano-oxidation technique of the DLC thin film. The comparative results show that the prediction accuracy of BPN is superior to that of MRA. When the BPN algorithm is used to predict nano-point machining, the mean absolute percentage errors (MAPE) of depth, left side, and right side are 8.02%, 9.68%, and 7.34%, respectively. When nano-line machining is being predicted, the MAPEs of depth, left side, and right side are 4.96%, 8.09%, and 6.77%, respectively. The obtained data can also be used to predict cross-sectional morphology in the DLC thin film treated with a nano-oxidation process. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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4645 KiB  
Article
An Investigation of the Microstructure of an Intermetallic Layer in Welding Aluminum Alloys to Steel by MIG Process
by Quoc Manh Nguyen and Shyh-Chour Huang
Materials 2015, 8(12), 8246-8254; https://doi.org/10.3390/ma8125444 - 02 Dec 2015
Cited by 26 | Viewed by 7519
Abstract
Butt joints of A5052 aluminum alloy and SS400 steel, with a new type of chamfered edge, are welded by means of metal inert gas welding and ER4043 Al-Si filler metal. The microhardness and microstructure of the joint are investigated. An intermetallic layer is [...] Read more.
Butt joints of A5052 aluminum alloy and SS400 steel, with a new type of chamfered edge, are welded by means of metal inert gas welding and ER4043 Al-Si filler metal. The microhardness and microstructure of the joint are investigated. An intermetallic layer is found on the surface of the welding seam and SS400 steel sheet. The hardness of the intermetallic layer is examined using the Vickers hardness test. The average hardness values at the Intermetallic (IMC) layer zone and without the IMC layer zone were higher than that of the welding wire ER4043. The tensile strength test showed a fracture at the intermetallic layer when the tensile strength is 225.9 MPa. The tensile value test indicated the average of welds was equivalent to the 85% tensile strength of the A5052 aluminum alloy. The thickness of the intermetallic layers is non-uniform at different positions with the ranges from 1.95 to 5 μm. The quality of the butt joint is better if the intermetallic layer is minimized. The Si crystals which appeared at the welding seam, indicating that this element participated actively during the welding process, also contributed to the IMC layer’s formation. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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1742 KiB  
Article
Origin of the Electroluminescence from Annealed-ZnO/GaN Heterojunction Light-Emitting Diodes
by Kai-Chiang Hsu, Wei-Hua Hsiao, Ching-Ting Lee, Yan-Ting Chen and Day-Shan Liu
Materials 2015, 8(11), 7745-7756; https://doi.org/10.3390/ma8115417 - 16 Nov 2015
Cited by 5 | Viewed by 5329
Abstract
This paper addressed the effect of post-annealed treatment on the electroluminescence (EL) of an n-ZnO/p-GaN heterojunction light-emitting diode (LED). The bluish light emitted from the 450 °C-annealed LED became reddish as the LED annealed at a temperature of 800 °C [...] Read more.
This paper addressed the effect of post-annealed treatment on the electroluminescence (EL) of an n-ZnO/p-GaN heterojunction light-emitting diode (LED). The bluish light emitted from the 450 °C-annealed LED became reddish as the LED annealed at a temperature of 800 °C under vacuum atmosphere. The origins of the light emission for these LEDs annealed at various temperatures were studied using measurements of electrical property, photoluminescence, and Auger electron spectroscopy (AES) depth profiles. A blue-violet emission located at 430 nm was associated with intrinsic transitions between the bandgap of n-ZnO and p-GaN, the green-yellow emission at 550 nm mainly originating from the deep-level transitions of native defects in the n-ZnO and p-GaN surfaces, and the red emission at 610 nm emerging from the Ga-O interlayer due to interdiffusion at the n-ZnO/p-GaN interface. The above-mentioned emissions also supported the EL spectra of LEDs annealed at 700 °C under air, nitrogen, and oxygen atmospheres, respectively. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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3811 KiB  
Article
Effects of Electrodes on the Switching Behavior of Strontium Titanate Nickelate Resistive Random Access Memory
by Ke-Jing Lee, Li-Wen Wang, Te-Kung Chiang and Yeong-Her Wang
Materials 2015, 8(10), 7191-7198; https://doi.org/10.3390/ma8105374 - 26 Oct 2015
Cited by 43 | Viewed by 6427
Abstract
Strontium titanate nickelate (STN) thin films on indium tin oxide (ITO)/glass substrate were synthesized using the sol-gel method for resistive random access memory (RRAM) applications. Aluminum (Al), titanium (Ti), tungsten (W), gold (Au) and platinum (Pt) were used as top electrodes in the [...] Read more.
Strontium titanate nickelate (STN) thin films on indium tin oxide (ITO)/glass substrate were synthesized using the sol-gel method for resistive random access memory (RRAM) applications. Aluminum (Al), titanium (Ti), tungsten (W), gold (Au) and platinum (Pt) were used as top electrodes in the STN-based RRAM to probe the switching behavior. The bipolar resistive switching behavior of the set and reset voltages is in opposite bias in the Al/STN/ITO and Pt/STN/ITO RRAMs, which can be partly ascribed to the different work functions of top electrodes in the ITO. Analyses of the fitting results and temperature-dependent performances showed that the Al/STN/ITO switching was mainly attributed to the absorption/release of oxygen-based functional groups, whereas the Pt/STN/ITO switching can be associated with the diffusion of metal electrode ions. The Al/STN/ITO RRAM demonstrated a high resistance ratio of >106 between the high-resistance state (HRS) and the low-resistance state (LRS), as well as a retention ability of >105 s. Furthermore, the Pt/STN/ITO RRAM displayed a HRS/LRS resistance ratio of >103 and a retention ability of >105 s. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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1812 KiB  
Article
Improving Non-Destructive Concrete Strength Tests Using Support Vector Machines
by Yi-Fan Shih, Yu-Ren Wang, Kuo-Liang Lin and Chin-Wen Chen
Materials 2015, 8(10), 7169-7178; https://doi.org/10.3390/ma8105368 - 22 Oct 2015
Cited by 29 | Viewed by 7907
Abstract
Non-destructive testing (NDT) methods are important alternatives when destructive tests are not feasible to examine the in situ concrete properties without damaging the structure. The rebound hammer test and the ultrasonic pulse velocity test are two popular NDT methods to examine the properties [...] Read more.
Non-destructive testing (NDT) methods are important alternatives when destructive tests are not feasible to examine the in situ concrete properties without damaging the structure. The rebound hammer test and the ultrasonic pulse velocity test are two popular NDT methods to examine the properties of concrete. The rebound of the hammer depends on the hardness of the test specimen and ultrasonic pulse travelling speed is related to density, uniformity, and homogeneity of the specimen. Both of these two methods have been adopted to estimate the concrete compressive strength. Statistical analysis has been implemented to establish the relationship between hammer rebound values/ultrasonic pulse velocities and concrete compressive strength. However, the estimated results can be unreliable. As a result, this research proposes an Artificial Intelligence model using support vector machines (SVMs) for the estimation. Data from 95 cylinder concrete samples are collected to develop and validate the model. The results show that combined NDT methods (also known as SonReb method) yield better estimations than single NDT methods. The results also show that the SVM model is more accurate than the statistical regression model. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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2525 KiB  
Article
A Micro Rectangular-Shaped Long-Period Fiber Grating Coated With Fe3O4 Nanoparticle Thin Overlay For Magnetic Sensing
by Sheng-Feng Wang and Chia-Chin Chiang
Materials 2015, 8(10), 7074-7083; https://doi.org/10.3390/ma8105361 - 19 Oct 2015
Cited by 2 | Viewed by 5056
Abstract
In this paper, we provide a novel micro rectangular-shaped long-period fiber grating (MRSLPFG) coated with Fe3O4 nanoparticles as the sensing material and packaged in polydimethylsiloxane (PDMS) for magnetic sensing application. The micro rectangular-shaped grating structures are fully dip coated with [...] Read more.
In this paper, we provide a novel micro rectangular-shaped long-period fiber grating (MRSLPFG) coated with Fe3O4 nanoparticles as the sensing material and packaged in polydimethylsiloxane (PDMS) for magnetic sensing application. The micro rectangular-shaped grating structures are fully dip coated with the magnetic fluid and heated to form a thin solid film. This thin overlay is used as the sensing media to measure the external magnetic flux density parallel to the optical fiber axis. According to our experimental results, the phenomenon of the transmission loss of the MRSLPFG magnetic sensor was increased monotonically when the external applied magnetic flux density increased. As the external applied magnetic flux density was increased from 0 to 91.10 mT, the resonance attenuation dip of the MRSLPFG increased and the average sensitivity achieved during the experiments was 0.129 dB/mT. We infer that the aforementioned experimental results were due to the magnetostrictive effect exerted on the thin layer of Fe3O4 nanoparticles, which in turn induced slight longitudinal strains on the micro rectangular-shaped fiber grating structures under different magnetic flux density. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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2563 KiB  
Article
Characterization and Curing Kinetics of Epoxy/Silica Nano-Hybrids
by Cheng-Fu Yang, Li-Fen Wang, Song-Mao Wu and Chean-Cheng Su
Materials 2015, 8(10), 7032-7040; https://doi.org/10.3390/ma8105357 - 16 Oct 2015
Cited by 7 | Viewed by 5378
Abstract
The sol-gel technique was used to prepare epoxy/silica nano-hybrids. The thermal characteristics, curing kinetics and structure of epoxy/silica nano-hybrids were studied using differential scanning calorimetry (DSC), 29Si nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM). To improve the compatibility between the [...] Read more.
The sol-gel technique was used to prepare epoxy/silica nano-hybrids. The thermal characteristics, curing kinetics and structure of epoxy/silica nano-hybrids were studied using differential scanning calorimetry (DSC), 29Si nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM). To improve the compatibility between the organic and inorganic phases, a coupling agent was used to modify the diglycidyl ether of bisphenol A (DGEBA) epoxy. The sol-gel technique enables the silica to be successfully incorporated into the network of the hybrids, increasing the thermal stability and improving the mechanical properties of the prepared epoxy/silica nano-hybrids. An autocatalytic mechanism of the epoxy/SiO2 nanocomposites was observed. The low reaction rate of epoxy in the nanocomposites is caused by the steric hindrance in the network of hybrids that arises from the consuming of epoxide group in the network of hybrids by the silica. In the nanocomposites, the nano-scale silica particles had an average size of approximately 35 nm, and the particles were well dispersed in the epoxy matrix, according to the TEM images. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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612 KiB  
Article
The Promotion Strategy of Green Construction Materials: A Path Analysis Approach
by Chung-Fah Huang and Jung-Lu  Chen
Materials 2015, 8(10), 6999-7005; https://doi.org/10.3390/ma8105354 - 14 Oct 2015
Cited by 6 | Viewed by 5264
Abstract
As one of the major materials used in construction, cement can be very resource-consuming and polluting to produce and use. Compared with traditional cement processing methods, dry-mix mortar is more environmentally friendly by reducing waste production or carbon emissions. Despite the continuous development [...] Read more.
As one of the major materials used in construction, cement can be very resource-consuming and polluting to produce and use. Compared with traditional cement processing methods, dry-mix mortar is more environmentally friendly by reducing waste production or carbon emissions. Despite the continuous development and promotion of green construction materials, only a few of them are accepted or widely used in the market. In addition, the majority of existing research on green construction materials focuses more on their physical or chemical characteristics than on their promotion. Without effective promotion, their benefits cannot be fully appreciated and realized. Therefore, this study is conducted to explore the promotion of dry-mix mortars, one of the green materials. This study uses both qualitative and quantitative methods. First, through a case study, the potential of reducing carbon emission is verified. Then a path analysis is conducted to verify the validity and predictability of the samples based on the technology acceptance model (TAM) in this study. According to the findings of this research, to ensure better promotion results and wider application of dry-mix mortar, it is suggested that more systematic efforts be invested in promoting the usefulness and benefits of dry-mix mortar. The model developed in this study can provide helpful references for future research and promotion of other green materials. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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12177 KiB  
Article
Improving Efficiency of Multicrystalline Silicon and CIGS Solar Cells by Incorporating Metal Nanoparticles
by Ming-Jer Jeng, Zih-Yang Chen, Yu-Ling Xiao, Liann-Be Chang, Jianping Ao, Yun Sun, Ewa Popko, Witold Jacak and Lee Chow
Materials 2015, 8(10), 6761-6771; https://doi.org/10.3390/ma8105337 - 08 Oct 2015
Cited by 25 | Viewed by 5973
Abstract
This work studies the use of gold (Au) and silver (Ag) nanoparticles in multicrystalline silicon (mc-Si) and copper-indium-gallium-diselenide (CIGS) solar cells. Au and Ag nanoparticles are deposited by spin-coating method, which is a simple and low cost process. The random distribution of nanoparticles [...] Read more.
This work studies the use of gold (Au) and silver (Ag) nanoparticles in multicrystalline silicon (mc-Si) and copper-indium-gallium-diselenide (CIGS) solar cells. Au and Ag nanoparticles are deposited by spin-coating method, which is a simple and low cost process. The random distribution of nanoparticles by spin coating broadens the resonance wavelength of the transmittance. This broadening favors solar cell applications. Metal shadowing competes with light scattering in a manner that varies with nanoparticle concentration. Experimental results reveal that the mc-Si solar cells that incorporate Au nanoparticles outperform those with Ag nanoparticles. The incorporation of suitable concentration of Au and Ag nanoparticles into mc-Si solar cells increases their efficiency enhancement by 5.6% and 4.8%, respectively. Incorporating Au and Ag nanoparticles into CIGS solar cells improve their efficiency enhancement by 1.2% and 1.4%, respectively. The enhancement of the photocurrent in mc-Si solar cells is lower than that in CIGS solar cells, owing to their different light scattering behaviors and material absorption coefficients. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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1587 KiB  
Article
Effect of Annealing Process on the Properties of Ni(55%)Cr(40%)Si(5%) Thin-Film Resistors
by Huan-Yi Cheng, Ying-Chung Chen, Pei-Jou Li, Cheng-Fu Yang and Hong-Hsin Huang
Materials 2015, 8(10), 6752-6760; https://doi.org/10.3390/ma8105338 - 02 Oct 2015
Cited by 12 | Viewed by 7013
Abstract
Resistors in integrated circuits (ICs) are implemented using diffused methods fabricated in the base and emitter regions of bipolar transistor or in source/drain regions of CMOS. Deposition of thin films on the wafer surface is another choice to fabricate the thin-film resistors in [...] Read more.
Resistors in integrated circuits (ICs) are implemented using diffused methods fabricated in the base and emitter regions of bipolar transistor or in source/drain regions of CMOS. Deposition of thin films on the wafer surface is another choice to fabricate the thin-film resistors in ICs’ applications. In this study, Ni(55%)Cr(40%)Si(5%) (abbreviated as NiCrSi) in wt % was used as the target and the sputtering method was used to deposit the thin-film resistors on Al2O3 substrates. NiCrSi thin-film resistors with different thicknesses of 30.8 nm~334.7 nm were obtained by controlling deposition time. After deposition, the thin-film resistors were annealed at 400 °C under different durations in N2 atmosphere using the rapid thermal annealing (RTA) process. The sheet resistance of NiCrSi thin-film resistors was measured using the four-point-probe method from 25 °C to 125 °C, then the temperature coefficient of resistance could be obtained. We aim to show that resistivity of NiCrSi thin-film resistors decreased with increasing deposition time (thickness) and the annealing process had apparent effect on the sheet resistance and temperature coefficient of resistance. We also aim to show that the annealed NiCrSi thin-film resistors had a low temperature coefficient of resistance (TCR) between 0 ppm/°C and +50 ppm/°C. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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9066 KiB  
Article
Performance-Enhanced Textured Silicon Solar Cells Based on Plasmonic Light Scattering Using Silver and Indium Nanoparticles
by Wen-Jeng Ho, Shih-Ya Su, Yi-Yu Lee, Hong-Jhang Syu and Ching-Fuh Lin
Materials 2015, 8(10), 6668-6676; https://doi.org/10.3390/ma8105330 - 25 Sep 2015
Cited by 19 | Viewed by 6496
Abstract
Performances of textured crystalline-silicon (c-Si) solar cells enhanced by silver nanoparticles (Ag-NPs) and indium nanoparticles (In-NPs) plasmonic effects are experimentally demonstrated and compared. Plasmonic nanoparticles integrated into textured c-Si solar cells can further increase the absorption and enhance the short-circuit current density ( [...] Read more.
Performances of textured crystalline-silicon (c-Si) solar cells enhanced by silver nanoparticles (Ag-NPs) and indium nanoparticles (In-NPs) plasmonic effects are experimentally demonstrated and compared. Plasmonic nanoparticles integrated into textured c-Si solar cells can further increase the absorption and enhance the short-circuit current density (Jsc) of the solar cell. To examine the profile of the proposed metallic particles, the average diameter and coverage of the In-NPs (Ag-NPs) at 17.7 nm (19.07 nm) and 30.5% (35.1%), respectively, were obtained using scanning electron microscopy. Optical reflectance and external quantum efficiency response were used to measure plasmonic light scattering at various wavelengths. Compared to a bare reference cell, the application of In-NPs increased the Jsc of the cells by 8.64% (from 30.32 to 32.94 mA/cm2), whereas the application of Ag-NPs led to an increase of 4.71% (from 30.32 to 31.75 mA/cm2). The conversion efficiency of cells with embedded In-NPs (14.85%) exceeded that of cells with embedded Ag-NPs (14.32%), which can be attributed to the broadband plasmonic light scattering of the In-NPs. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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7415 KiB  
Article
Wear Improvement of Tools in the Cold Forging Process for Long Hex Flange Nuts
by Shao-Yi Hsia and Po-Yueh Shih
Materials 2015, 8(10), 6640-6657; https://doi.org/10.3390/ma8105328 - 25 Sep 2015
Cited by 21 | Viewed by 11733
Abstract
Cold forging has played a critical role in fasteners and has been widely used in automotive production, manufacturing, aviation and 3C (Computer, Communication, and Consumer electronics). Despite its extensive use in fastener forming and die design, operator experience and trial and error make [...] Read more.
Cold forging has played a critical role in fasteners and has been widely used in automotive production, manufacturing, aviation and 3C (Computer, Communication, and Consumer electronics). Despite its extensive use in fastener forming and die design, operator experience and trial and error make it subjective and unreliable owing to the difficulty of controlling the development schedule. This study used finite element analysis to establish and simulate wear in automotive repair fastener manufacturing dies based on actual process conditions. The places on a die that wore most quickly were forecast, with the stress levels obtained being substituted into the Archard equation to calculate die wear. A 19.87% improvement in wear optimization occurred by applying the Taguchi quality method to the new design. Additionally, a comparison of actual manufacturing data to simulations revealed a nut forging size error within 2%, thereby demonstrating the accuracy of this theoretical analysis. Finally, SEM micrographs of the worn surfaces on the upper punch indicate that the primary wear mechanism on the cold forging die for long hex flange nuts was adhesive wear. The results can simplify the development schedule, reduce the number of trials and further enhance production quality and die life. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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2041 KiB  
Article
Aspherical Lens Design Using Genetic Algorithm for Reducing Aberrations in Multifocal Artificial Intraocular Lens
by Chih-Ta Yen and Shih-Cyuan Jin
Materials 2015, 8(9), 6309-6325; https://doi.org/10.3390/ma8095305 - 17 Sep 2015
Cited by 5 | Viewed by 6303
Abstract
A complex intraocular lens (IOL) design involving numerous uncertain variables is proposed. We integrated a genetic algorithm (GA) with the commercial optical design software of (CODE V) to design a multifocal IOL for the human eye. We mainly used an aspherical lens in [...] Read more.
A complex intraocular lens (IOL) design involving numerous uncertain variables is proposed. We integrated a genetic algorithm (GA) with the commercial optical design software of (CODE V) to design a multifocal IOL for the human eye. We mainly used an aspherical lens in the initial state to the crystalline type; therefore, we used the internal human eye model in the software. The proposed optimized algorithm employs a GA method for optimally simulating the focusing function of the human eye; in this method, the thickness and curvature of the anterior lens and the posterior part of the IOL were varied. A comparison of the proposed GA-designed IOLs and those designed using a CODE V built-in optimal algorithm for 550 degrees myopia and 175 degrees astigmatism conditions of the human eye for pupil size 6 mm showed that the proposed IOL design improved the spot size of root mean square (RMS), tangential coma (TCO) and modulation transfer function (MTF) at a spatial frequency of 30 with a pupil size of 6 mm by approximately 17%, 43% and 35%, respectively. However, the worst performance of spherical aberration (SA) was lower than 46%, because the optical design involves a tradeoff between all aberrations. Compared with the traditional CODE V built-in optimal scheme, the proposed IOL design can efficiently improve the critical parameters, namely TCO, RMS, and MTF. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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3218 KiB  
Article
Light Absorption Enhancement of Silicon-Based Photovoltaic Devices with Multiple Bandgap Structures of Porous Silicon
by Kuen-Hsien Wu and Chong-Wei Li
Materials 2015, 8(9), 5922-5932; https://doi.org/10.3390/ma8095283 - 07 Sep 2015
Cited by 12 | Viewed by 6682
Abstract
Porous-silicon (PS) multi-layered structures with three stacked PS layers of different porosity were prepared on silicon (Si) substrates by successively tuning the electrochemical-etching parameters in an anodization process. The three PS layers have different optical bandgap energy and construct a triple-layered PS (TLPS) [...] Read more.
Porous-silicon (PS) multi-layered structures with three stacked PS layers of different porosity were prepared on silicon (Si) substrates by successively tuning the electrochemical-etching parameters in an anodization process. The three PS layers have different optical bandgap energy and construct a triple-layered PS (TLPS) structure with multiple bandgap energy. Photovoltaic devices were fabricated by depositing aluminum electrodes of Schottky contacts on the surfaces of the developed TLPS structures. The TLPS-based devices exhibit broadband photoresponses within the spectrum of the solar irradiation and get high photocurrent for the incident light of a tungsten lamp. The improved spectral responses of devices are owing to the multi-bandgap structures of TLPS, which are designed with a layered configuration analog to a tandem cell for absorbing a wider energy range of the incidental sun light. The large photocurrent is mainly ascribed to an enhanced light-absorption ability as a result of applying nanoporous-Si thin films as the surface layers to absorb the short-wavelength light and to improve the Schottky contacts of devices. Experimental results reveal that the multi-bandgap PS structures produced from electrochemical-etching of Si wafers are potentially promising for development of highly efficient Si-based solar cells. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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2814 KiB  
Article
Thermal and Mechanical Behavior of Hybrid Polymer Nanocomposite Reinforced with Graphene Nanoplatelets
by Minh-Tai Le and Shyh-Chour Huang
Materials 2015, 8(8), 5526-5536; https://doi.org/10.3390/ma8085262 - 24 Aug 2015
Cited by 70 | Viewed by 8941
Abstract
In the present investigation, we successfully fabricate a hybrid polymer nanocomposite containing epoxy/polyester blend resin and graphene nanoplatelets (GNPs) by a novel technique. A high intensity ultrasonicator is used to obtain a homogeneous mixture of epoxy/polyester resin and graphene nanoplatelets. This mixture is [...] Read more.
In the present investigation, we successfully fabricate a hybrid polymer nanocomposite containing epoxy/polyester blend resin and graphene nanoplatelets (GNPs) by a novel technique. A high intensity ultrasonicator is used to obtain a homogeneous mixture of epoxy/polyester resin and graphene nanoplatelets. This mixture is then mixed with a hardener using a high-speed mechanical stirrer. The trapped air and reaction volatiles are removed from the mixture using high vacuum. The hot press casting method is used to make the nanocomposite specimens. Tensile tests, dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) are performed on neat, 0.2 wt %, 0.5 wt %, 1 wt %, 1.5 wt % and 2 wt % GNP-reinforced epoxy/polyester blend resin to investigate the reinforcement effect on the thermal and mechanical properties of the nanocomposites. The results of this research indicate that the tensile strength of the novel nanocomposite material increases to 86.8% with the addition of a ratio of graphene nanoplatelets as low as 0.2 wt %. DMA results indicate that the 1 wt % GNP-reinforced epoxy/polyester nanocomposite possesses the highest storage modulus and glass transition temperature (Tg), as compared to neat epoxy/polyester or the other nanocomposite specimens. In addition, TGA results verify thethermal stability of the experimental specimens, regardless of the weight percentage of GNPs. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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7106 KiB  
Article
Fabrication of CH3NH3PbI3/PVP Composite Fibers via Electrospinning and Deposition
by Li-Min Chao, Ting-Yu Tai, Yueh-Ying Chen, Pei-Ying Lin and Yaw-Shyan Fu
Materials 2015, 8(8), 5467-5478; https://doi.org/10.3390/ma8085256 - 21 Aug 2015
Cited by 19 | Viewed by 9811
Abstract
In our study, one-dimensional PbI2/polyvinylpyrrolidone (PVP) composition fibers have been prepared by using PbI2 and PVP as precursors dissolved in N,N-dimethylformamide via a electrospinning process. Dipping the fibers into CH3NH3I solution changed its [...] Read more.
In our study, one-dimensional PbI2/polyvinylpyrrolidone (PVP) composition fibers have been prepared by using PbI2 and PVP as precursors dissolved in N,N-dimethylformamide via a electrospinning process. Dipping the fibers into CH3NH3I solution changed its color, indicating the formation of CH3NH3PbI3, to obtain CH3NH3PbI3/PVP composite fibers. The structure, morphology and composition of the all as-prepared fibers were characterized by using X-ray diffraction and scanning electron microscopy. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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3284 KiB  
Article
Investigation of Laminar Convective Heat Transfer for Al2O3-Water Nanofluids Flowing through a Square Cross-Section Duct with a Constant Heat Flux
by Hsien-Hung Ting and Shuhn-Shyurng Hou
Materials 2015, 8(8), 5321-5335; https://doi.org/10.3390/ma8085246 - 19 Aug 2015
Cited by 25 | Viewed by 6739
Abstract
The objective of this study is to numerically investigate the convective heat transfer of water-based Al2O3 nanofluids flowing through a square cross-section duct with a constant heat flux under laminar flow conditions. The effects of nanoparticle concentration and Peclet number on the heat [...] Read more.
The objective of this study is to numerically investigate the convective heat transfer of water-based Al2O3 nanofluids flowing through a square cross-section duct with a constant heat flux under laminar flow conditions. The effects of nanoparticle concentration and Peclet number on the heat transfer characteristics of Al2O3-water nanofluids are investigated. The nanoparticle diameter is 25 nm and six particle concentrations (0.2, 0.5, 1, 1.5, 2, and 2.5 vol.%) are considered. The numerical results show that the heat transfer coefficients and Nusselt numbers of Al2O3-water nanofluids increase with increases in the Peclet number as well as particle volume concentration. The heat transfer coefficient of nanofluids is increased by 25.5% at a particle volume concentration of 2.5% and a Peclet number of 7500 as compared with that of the base fluid (pure water). It is noteworthy that at the same particle volume concentration of 2.5%, the enhancement of the convective heat transfer coefficient of Al2O3-water nanofluid (25.5%) is much higher than that of the effective thermal conductivity (9.98%). Thus, the enhancement of the convective heat transfer cannot be solely attributed to the enhancement of the effective thermal conductivity. Additionally, the numerical results coincide well with the published experimental data. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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1929 KiB  
Article
Capacitive Behavior of Single Gallium Oxide Nanobelt
by Haitao Cai, Hang Liu, Huichao Zhu, Pai Shao and Changmin Hou
Materials 2015, 8(8), 5313-5320; https://doi.org/10.3390/ma8085244 - 17 Aug 2015
Cited by 5 | Viewed by 5268
Abstract
In this research, monocrystalline gallium oxide (Ga2O3) nanobelts were synthesized through oxidation of metal gallium at high temperature. An electronic device, based on an individual Ga2O3 nanobelt on Pt interdigital electrodes (IDEs), was fabricated to investigate [...] Read more.
In this research, monocrystalline gallium oxide (Ga2O3) nanobelts were synthesized through oxidation of metal gallium at high temperature. An electronic device, based on an individual Ga2O3 nanobelt on Pt interdigital electrodes (IDEs), was fabricated to investigate the electrical characteristics of the Ga2O3 nanobelt in a dry atmosphere at room temperature. The current-voltage (I-V) and I/V-t characteristics show the capacitive behavior of the Ga2O3 nanobelt, indicating the existence of capacitive elements in the Pt/Ga2O3/Pt structure. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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6535 KiB  
Article
Effect of Annealing Temperature and Oxygen Flow in the Properties of Ion Beam Sputtered SnO—2x Thin Films
by Chun-Min Wang, Chun-Chieh Huang, Jui-Chao Kuo, Dipti Ranjan Sahu and Jow-Lay Huang
Materials 2015, 8(8), 5289-5297; https://doi.org/10.3390/ma8085243 - 14 Aug 2015
Cited by 9 | Viewed by 6489
Abstract
Tin oxide (SnO2—x) thin films were prepared under various flow ratios of O2/(O2 + Ar) on unheated glass substrate using the ion beam sputtering (IBS) deposition technique. This work studied the effects of the flow ratio of O [...] Read more.
Tin oxide (SnO2—x) thin films were prepared under various flow ratios of O2/(O2 + Ar) on unheated glass substrate using the ion beam sputtering (IBS) deposition technique. This work studied the effects of the flow ratio of O2/(O2 + Ar), chamber pressures and post-annealing treatment on the physical properties of SnO2 thin films. It was found that annealing affects the crystal quality of the films as seen from both X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis. In addition, the surface RMS roughness was measured with atomic force microscopy (AFM). Auger electron spectroscopy (AES) analysis was used to obtain the changes of elemental distribution between tin and oxygen atomic concentration. The electrical property is discussed with attention to the structure factor. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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2521 KiB  
Article
Enhanced Synthesis of Carbon Nanomaterials Using Acoustically Excited Methane Diffusion Flames
by Shuhn-Shyurng Hou, Kuan-Ming Chen, Zong-Yun Yang and Ta-Hui Lin
Materials 2015, 8(8), 4805-4816; https://doi.org/10.3390/ma8084805 - 29 Jul 2015
Cited by 9 | Viewed by 4281
Abstract
Acoustically modulated methane jet diffusion flames were used to enhance carbon nanostructure synthesis. A catalytic nickel substrate was employed to collect the deposit materials at sampling position z = 10 mm above the burner exit. The fabrication of carbon nano-onions (CNOs) and carbon [...] Read more.
Acoustically modulated methane jet diffusion flames were used to enhance carbon nanostructure synthesis. A catalytic nickel substrate was employed to collect the deposit materials at sampling position z = 10 mm above the burner exit. The fabrication of carbon nano-onions (CNOs) and carbon nanotubes (CNTs) was significantly enhanced by acoustic excitation at frequencies near the natural flickering frequency (ƒ = 20 Hz) and near the acoustically resonant frequency (ƒ = 90 Hz), respectively. At these characteristic frequencies, flow mixing was markedly enhanced by acoustic excitation, and a flame structure with a bright slender core flame was generated, which provided a favorable flame environment for the growth of carbon nanomaterials. The production rate of CNOs was high at 20 Hz (near the natural flickering frequency), at which the gas temperature was about 680 °C. Additionally, a quantity of CNTs was obtained at 70–95 Hz, near the acoustically resonant frequency, at which the gas temperature was between 665 and 830 °C. However, no carbon nanomaterials were synthesized at other frequencies. The enhanced synthesis of CNOs and CNTs is attributed to the strong mixing of the fuel and oxidizer due to the acoustic excitation at resonant frequencies. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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1554 KiB  
Article
Notched Long-Period Fiber Grating with an Amine-Modified Surface Nanostructure for Carbon Dioxide Gas Sensing
by Janw-Wei Wu and Chia-Chin Chiang
Materials 2015, 8(7), 4535-4543; https://doi.org/10.3390/ma8074535 - 21 Jul 2015
Cited by 8 | Viewed by 5255
Abstract
This paper presents the fabrication and application of a notched long-period fiber grating (NLPFG) with an amine-modified surface nanostructure for carbon dioxide (CO2) gas sensing. The NLPFG with the modified surface nanostructure was fabricated by using inductively coupled plasma (ICP) etching [...] Read more.
This paper presents the fabrication and application of a notched long-period fiber grating (NLPFG) with an amine-modified surface nanostructure for carbon dioxide (CO2) gas sensing. The NLPFG with the modified surface nanostructure was fabricated by using inductively coupled plasma (ICP) etching with an Ag nanoparticle etching barrier. The experimental results show that the spectra were changed with the CO2 gas flow within 12 min. Thereafter, the spectra of the NLPFG remained steady and unchanged. During the absorption process, the transmission loss was decreased by approximately 2.019 dB, and the decreased rate of transmission loss was 0.163 dB/min. The sensitivity was about −0.089 dB/%. These results demonstrate that the NLPFG CO2 gas sensor has the advantages of steady performance, repeatability, and low cost. Therefore, the NLPFG can be utilized as a reliable CO2 gas sensor. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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3449 KiB  
Article
Preparation and Properties of (YCa)(TiMn)O3−d Ceramics Interconnect of Solid Oxide Fuel Cells
by Yi-Cheng Liou, Wen-Chou Tsai, Hao-Hsuan Yen and Yung-Chia Chang
Materials 2015, 8(7), 4239-4248; https://doi.org/10.3390/ma8074239 - 10 Jul 2015
Cited by 1 | Viewed by 4487
Abstract
(YCa)(TiMn)O3–d ceramics prepared using a reaction-sintering process were investigated. Without any calcination involved, the mixture of raw materials was pressed and sintered directly. Y2Ti2O7 instead of YTiO3 formed when a mixture of Y2O [...] Read more.
(YCa)(TiMn)O3–d ceramics prepared using a reaction-sintering process were investigated. Without any calcination involved, the mixture of raw materials was pressed and sintered directly. Y2Ti2O7 instead of YTiO3 formed when a mixture of Y2O3 and TiO2 with Y/Ti ratio 1/1 were sintered in air. Y2Ti2O7, YTiO2.085 and some unknown phases were detected in Y0.6Ca0.4Ti0.6Mn0.4O3–d. Monophasic Y0.6Ca0.4Ti0.4Mn0.6O3–d ceramics were obtained after 1400–1500 °C sintering. Dense Y0.6Ca0.4Ti0.4Mn0.6O3–d with a density 4.69 g/cm3 was observed after 1500 °C/4 h sintering. Log σ for Y0.6Ca0.4Ti0.6Mn0.4O3–d increased from –3.73 Scm–1 at 350 °C to –2.14 Scm–1 at 700 °C. Log σ for Y0.6Ca0.4Ti0.4Mn0.6O3–d increased from –2.1 Scm–1 at 350 °C to –1.36 Scm–1 at 700 °C. Increasing Mn content decreased activation energy Ea and increased electrical conductivity. Reaction-sintering process is proved to be a simple and effective method to obtain (YCa)(TiMn)O3–d ceramics for interconnects in solid oxide fuel cells. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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1424 KiB  
Article
Investigation of the High Mobility IGZO Thin Films by Using Co-Sputtering Method
by Chao-Ming Hsu, Wen-Cheng Tzou, Cheng-Fu Yang and Yu-Jhen Liou
Materials 2015, 8(5), 2769-2781; https://doi.org/10.3390/ma8052769 - 21 May 2015
Cited by 43 | Viewed by 9230
Abstract
High transmittance ratio in visible range, low resistivity, and high mobility of IGZO thin films were prepared at room temperature for 30 min by co-sputtering of Zn2Ga2O5 (Ga2O3 + 2 ZnO, GZO) ceramic and In [...] Read more.
High transmittance ratio in visible range, low resistivity, and high mobility of IGZO thin films were prepared at room temperature for 30 min by co-sputtering of Zn2Ga2O5 (Ga2O3 + 2 ZnO, GZO) ceramic and In2O3 ceramic at the same time. The deposition power of pure In2O3 ceramic target was fixed at 100 W and the deposition power of GZO ceramic target was changed from 80 W to 140 W. We chose to investigate the deposition power of GZO ceramic target on the properties of IGZO thin films. From the SEM observations, all of the deposited IGZO thin films showed a very smooth and featureless surface. From the measurements of XRD patterns, only the amorphous structure was observed. We aimed to show that the deposition power of GZO ceramic target had large effect on the Eg values, Hall mobility, carrier concentration, and resistivity of IGZO thin films. Secondary ion mass spectrometry (SIMS) analysis in the thicknesses’ profile of IGZO thin films found that In and Ga elements were uniform distribution and Zn element were non-uniform distribution. The SIMS analysis results also showed the concentrations of Ga and Zn elements increased and the concentrations of In element was almost unchanged with increasing deposition power. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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1533 KiB  
Article
Effect of Refractive Index of Substrate on Fabrication and Optical Properties of Hybrid Au-Ag Triangular Nanoparticle Arrays
by Jing Liu, Yushan Chen, Haoyuan Cai, Xiaoyi Chen, Changwei Li and Cheng-Fu Yang
Materials 2015, 8(5), 2688-2699; https://doi.org/10.3390/ma8052688 - 19 May 2015
Cited by 11 | Viewed by 6613
Abstract
In this study, the nanosphere lithography (NSL) method was used to fabricate hybrid Au-Ag triangular periodic nanoparticle arrays. The Au-Ag triangular periodic arrays were grown on different substrates, and the effect of the refractive index of substrates on fabrication and optical properties was [...] Read more.
In this study, the nanosphere lithography (NSL) method was used to fabricate hybrid Au-Ag triangular periodic nanoparticle arrays. The Au-Ag triangular periodic arrays were grown on different substrates, and the effect of the refractive index of substrates on fabrication and optical properties was systematically investigated. At first, the optical spectrum was simulated by the discrete dipole approximation (DDA) numerical method as a function of refractive indexes of substrates and mediums. Simulation results showed that as the substrates had the refractive indexes of 1.43 (quartz) and 1.68 (SF5 glass), the nanoparticle arrays would have better refractive index sensitivity (RIS) and figure of merit (FOM). Simulation results also showed that the peak wavelength of the extinction spectra had a red shift when the medium’s refractive index n increased. The experimental results also demonstrated that when refractive indexes of substrates were 1.43 and 1.68, the nanoparticle arrays and substrate had better adhesive ability. Meanwhile, we found the nanoparticles formed a large-scale monolayer array with the hexagonally close-packed structure. Finally, the hybrid Au-Ag triangular nanoparticle arrays were fabricated on quartz and SF5 glass substrates and their experiment extinction spectra were compared with the simulated results. Full article
(This article belongs to the Special Issue Selected Papers from ICASI 2015)
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