Browsing by Issue Date, starting with "2015-03-04"

Now showing 1 - 20 of 22304

Use of Ultrafast Time-Resolved Spectroscopy to Demonstrate the Effect of Annealing on the Performance of P3HT:PCBM Solar Cells
(2015-03-04)
Wang, Yu-Ting
;
Chen, Mei-Hsin
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Lin, Chao-Ting
;
Fang, Jian-Jhih
;
Chang, Che-Jui
The organic solar cells of heterojunction system, ITO/PEDOT:PSS/P3HT:PCBM/Al, with a thermal annealing after deposition of Al exhibit better performance than those with an annealing process before deposition of Al. In this study, ultrafast time-resolved spectroscopy is employed to reveal the underlying mechanism of annealing effects on the performance of P3HT:PCBM solar cell devices. The analyses of all decomposed relaxation processes show that the postannealed devices exhibit an increase in charge transfer, in the number of separated polarons and a reduction in the amount of recombination between excited carriers. Moreover, the longer lifetime for the excited carriers in postannealed devices indicates it is more likely to be dissociated into photocarriers and result in a larger value for photocurrent, which demonstrates the physical mechanism for increased device performance.
The benefits of a challenge: student motivation and flow experience in tablet-PC-game-based learning
(2015-03-04)
Hung, Cheng-Yu
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Sun, Jerry Chih-Yuan
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Yu, Pao-Ta
;
教育研究所
;
Institute of Education
Advances in technology have led to continuous innovation in teaching and learning methods. For instance, the use of tablet PCs (TPCs) in classroom instruction has been shown to be effective in attracting and motivating students\' interest and increasing their desire to participate in learning activities. In this paper, we used a TPCs game - an iPad app called Motion Math: Hungry Fish - to help young students learn to theoretically understand and practically implement the mathematical concepts of addition and subtraction. Based on findings from a pilot study, we categorized the game\'s 18 levels of difficulty into "challenging" (experimental group) and "matching" (control group) games. We aimed to investigate whether challenging games were more able than matching games to improve the students\' motivation, flow experience, self-efficacy for technology, self-efficacy for science, feelings about the TPC game, and satisfaction with the learning approach. The findings showed that the students in the experimental group achieved better flow experience, learning performance, and satisfaction.
A powerful test for two-sided multiple independent characteristics supplier selection problem
(2015-03-04)
Wu, C. H.
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Pearn, W. L.
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Chuang, C. C.
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工業工程與管理學系
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Department of Industrial Engineering and Management
In this article, we consider the supplier selection problem for two-sided processes with multiple independent characteristics. We review the existing division method and develop a new exact approach called the subtraction method. For practical applications, a two-phase selection procedure is established based on the subtraction method. The decision powers of two methods are compared. We show that the subtraction method we proposed is indeed more powerful than the existing division method. Several figures are presented to display the required sample sizes with various powers and various values of (C-pk1(T), C-pk2(T)). For the convenience of practitioners, the required sample sizes for the two methods with various powers and various values of (C-pk1(T), C-pk2(T))) are also tabulated.
Detecting Misspecified Multilevel Structural Equation Models with Common Fit Indices: AMonte Carlo Study
(2015-03-04)
Hsu, Hsien-Yuan
;
Kwok, Oi-man
;
Lin, Jr Huang
;
Acosta, Sandra
;
教育研究所
This study investigated the sensitivity of common fit indices (i.e., RMSEA, CFI, TLI, SRMR-W, and SRMR-B) for detecting misspecified multilevel SEMs. The design factors for the Monte Carlo study were numbers of groups in between-group models (100, 150, and 300), group size (10, 20, 30, and 60), intra-class correlation (low, medium, and high), and the types of model misspecification (Simple and Complex). The simulation results showed that CFI, TLI, and RMSEA could only identify the misspecification in the within-group model. Additionally, CFI, TLI, and RMSEA were more sensitive to misspecification in pattern coefficients while SRMR-W was more sensitive to misspecification in factor covariance. Moreover, TLI outperformed both CFI and RMSEA in terms of the hit rates of detecting the within-group misspecification in factor covariance. On the other hand, SRMR-B was the only fit index sensitive to misspecification in the between-group model and more sensitive to misspecification in factor covariance than misspecification in pattern coefficients. Finally, we found that the influence of ICC on the performance of targeted fit indices was trivial.
Double-finger-gate controlled spin-resolved resonant quantum transport in the presence of a Rashba-Zeeman gap
(2015-03-04)
Tang, Chi-Shung
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Tseng, Shu-Ting
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Gudmundsson, Vidar
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Cheng, Shun-Jen
;
電子物理學系
We investigate double finger gate (DFG) controlled spin-resolved resonant transport properties in an n-type quantum channel with a Rashba-Zeeman (RZ) subband energy gap. By appropriately tuning the DFG in the strong Rashba coupling regime, resonant state structures in conductance can be found that are sensitive to the length of the DFG system. Furthermore, a hole-like bound state feature below the RZ gap and an electron-like quasi-bound state feature at the threshold of the upper spin branch can be found that is insensitive to the length of the DFG system.
High-efficiency parallel-plate wet scrubber (PPWS) for soluble gas removal
(2015-03-04)
Chien, Chih-Liang
;
Tsai, Chuen-Jinn
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Sheu, Shiang-Ru
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Cheng, Yu-Hsiang
;
Stank, Alexander Mihailovich
A parallel-plate wet scrubber (PPWS) was designed and tested to control low-concentration soluble acid gases using a multi-parallel-plate module (MPPM) to replace typical tower packings. The parallel plates in the MPPM were made of polypropylene coated with nano-TiO2 particles to enhance hydrophilicity for scrubbing liquid to form uniform liquid film. The gap between the plates was maintained at 3 mm, providing channels through which soluble gas pollutants in the upward gas stream were absorbed by the downward scrubbing liquid film on the surfaces. The removal efficiency was tested using HCl, HNO3, and CH3COOH of 0.02-2 ppmv at different retention times and liquid-to-gas ratios. Results show that when the retention time was 0.1, 0.3 and 0.5 s, the removal efficiency of the present scrubber for HCI, HNO3, and CH3COOH in low concentration was greater than 91%, 95%, and 98%, respectively. The MPPM significantly enhances the removal efficiency of the present scrubber, especially in low inlet concentration range (0.02-1 ppmv), which was greater than 99% for HCl and HNO3 and 98% for CH3COOH at the liquid-to-gas ratio of 18.5 L/m(3), the retention time of 0.5 s, and the pressure drop of 0.2 cm H2O. The experimental removal efficiencies of the MPPM are in good agreement with theoretical predictions. It is expected that the present PPWS can be scaled up as an efficient control device with low pressure drop for low-concentration soluble acid and basic gases. (C) 2015 Elsevier B.V. All rights reserved.
SINGLE CRYSTAL COPPER, MANUFACTURING METHOD THEREOF AND SUBSTRATE COMPRISING THE SAME
(2015-03-05)
CHEN Chih
;
TU King-Ning
;
LU Chia-Ling
The present invention relates to a single crystal copper having [100] orientation and a volume of 0.1˜4.0×106 μm3. The present invention further provides a manufacturing method for the single crystal copper and a substrate comprising the same.
Single-input multiple-output visible light optical wireless communications supporting quality of service
(2015-03-05)
Chen, Shih-Hao
;
Chow, Chi-Wai
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光電工程學系
;
Department of Photonics
Visible light optical wireless communication supporting single-input multiple-output quality of service (QoS) by using an indoor light-emitting diode, a mobile-phone camera and a photodetector is proposed and demonstrated for the first time. The proposed system can support two fixed-rate QoS transmissions for two different applications. By employing the rolling shutter effect of the mobile-phone camera, the data rate of the first data link can be greatly enhanced. The experimental result shows that the proposed system can support the first data link operated at 300 bit/s by using a mobile-phone camera and the second data link at 38.4 kbit/s by using a photodetector.
SECRET COMMUNICATION METHOD WITH SELF-AUTHENTICATION CAPABILITY
(2015-03-05)
LEE CHE-WEI
;
TSAI WEN-HSIANG
A secret communication method with a self-authentication capability is provided, which comprises steps of dividing a secret message into a plurality of secret segments; converting each of the secret segments into (k+1) shares, wherein k is a positive integer; embedding the shares into a media carrier; selecting every k shares among the (k+1) ones to compute (k+1) copies in value; and checking if the (k+1) copies in value are the same. If the (k+1) copies in value are the same, then the secret message is shown. Otherwise, at least one mark will be utilized to replace the secret message while the part of the secret message which is not falsified can still be correctly shown. By employing the method, the integrity and fidelity of the hidden secret message can thus be verified, thereby achieving a new covert communication process performing both information hiding and self-authentication capability.
Hybrid Dendrimer/Semiconductor Nanostructures with Efficient Energy Transfer via Optical Waveguiding
(2015-03-05)
Lin, T. N.
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Huang, J. C.
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Shen, J. L.
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Chu, C. M.
;
Yeh, J. M.
In this study, we demonstrated a nonradiative energy transfer between InGaN quantum wells (QWs) and polyamidoamine (PAMAM) dendrimers through optical waveguiding by detecting a reduction in the photoluminescence lifetime. The maximum energy transfer efficiency of this system is similar to 72%, which is promising for sensor applications. The energy transfer efficiency depends on the distance between the InGaN QWs and PAMAM dendrimers by a factor of 1/d(2), revealing layer-to-layer dipole interactions. Upon increasing the generation of PAMAM dendrimers, the transfer energy efficiency increases exponentially, which can be explained by the increased surface coverage for the higher generation.
GRAPHITE OXIDE AND GRAPHENE PREPARATION METHOD
(2015-03-05)
WEI Kung-Hwa
;
DANG Van Thanh
A graphite oxide and/or graphene preparation method includes providing a plasma electrolytic apparatus, wherein an electrolyte is provided and a graphite electrode is configured as a cathode of the plasma electrolytic apparatus; and providing a cathodic current so as to initiate a plasma electrolytic process at the graphite electrode to obtain graphite oxide and/or graphene. The graphite oxide and/or graphene can be synthesized through plasma electrolytic processing at relatively low temperature under atmospheric pressure within a very short period of time, without the need for concentrated acids or strong oxidizing agents. The present invention may prepare graphite oxide and/or graphene with plasma electrolytic process directly from graphite, without requiring any prior purification or pretreatment. This plasma electrolytic process of the present invention is quite promising and provided with advantages such as low cost, simple setup, high efficiency, and environmental friendliness.
Efficiency droop behavior improvement through barrier thickness modification for GaN-on-silicon light-emitting diodes
(2015-03-05)
Tzou, An-Jye
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Lin, Bing-Cheng
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Lee, Chia-Yu
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Lin, Da-Wei
;
Liao, Yu-Kuang
Crack-free GaN-based light-emitting diodes (LEDs) were grown on 150-mm-diameter Si substrates by using low-pressure metal-organic chemical vapor deposition. The relationship between the LED devices and the thickness of quantum barriers (QBs) was investigated. The crystal quality and surface cracking of GaN-on-Si were greatly improved by an AlxGa1-xN buffer layer composed of graded Al. The threading dislocation density of the GaN-on-Si LEDs was reduced to < 7 x 10(8) cm(-2), yielding LEDs with high internal quantum efficiency. Simulation results indicated that reducing the QB thickness improved the carrier injection rate and distribution, thereby improving the droop behavior of the LEDs. LEDs featuring 6-nm-thick QBs exhibited the lowest droop behavior. However, the experimental results showed an unanticipated phenomenon, namely that the peak external quantum efficiency (EQE) and light output power (LOP) gradually decreased with a decreasing QB thickness. In other words, the GaN-on-Si LEDs with 8-nm-thick QBs exhibited low droop behavior and yielded a good peak EQE and LOP, achieving a 22.9% efficiency droop and 54.6% EQE. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)
Direct Observation of the Solvent Effects on the Low-Lying ne and pi pi* Excited Triplet States of Acetophenone Derivatives in Thermal Equilibrium
(2015-03-05)
Narra, Sudhakar
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Shigeto, Shinsuke
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應用化學系
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應用化學系分子科學碩博班
;
Department of Applied Chemistry
Low-lying excited triplet states of aromatic carbonyl compounds exhibit diverse photophysical and photochemical properties of fundamental importance. Despite tremendous effort in studying those triplet states, the effects of substituents and solvents on the energetics of the triplet manifold and on photoreactivity remain to be fully understood. We have recently studied the ordering of the low-lying n pi* and pi pi* excited triplet states and its substituent dependence in acetophenone derivatives using nanosecond time-resolved near-IR (NIR) spectroscopy. Here we address the other important issue, the solvent effects, by directly observing the electronic bands in the NIR that originate from the lowest n pi* and pi pi* states of acetophenone derivatives in four solvents of different polarity (n-heptane, benzene, acetonitrile, and methanol). The two transient NIR bands decay synchronously in all the solvents, indicating that the lowest n pi* and pi pi* states are in thermal equilibrium irrespective of the solvent polarity studied here. We found that the pi pi* band increases in intensity relative to the n pi* band as solvent polarity increases. These results are compared with the photoreduction rate constant for the acetophenone derivatives in the solvents to which 2-propanol was added as a hydrogen-atom donor. Based on the present findings, we present a comprehensive, solvent- and substituent-dependent energy level diagram of the low-lying n pi* and pi pi* excited triplet states.
Donor-acceptor conjugated polymers based on multifused ladder-type arenes for organic solar cells
(2015-03-07)
Wu, Jhong-Sian
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Cheng, Sheng-Wen
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Cheng, Yen-Ju
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Hsu, Chain-Shu
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應用化學系
Harvesting solar energy from sunlight to generate electricity is considered as one of the most important technologies to address the future sustainability of humans. Polymer solar cells (PSCs) have attracted tremendous interest and attention over the past two decades due to their potential advantage to be fabricated onto large area and light-weight flexible substrates by solution processing at a lower cost. PSCs based on the concept of bulk heterojunction (BHJ) configuration where an active layer comprises a composite of a p-type (donor) and an n-type (acceptor) material represents the most useful strategy to maximize the internal donor-acceptor interfacial area allowing for efficient charge separation. Fullerene derivatives such as [ 6,6]-phenyl-C-61or 71-butyric acid methyl ester (PCBM) are the ideal n-type materials ubiquitously used for BHJ solar cells. The major effort to develop photoactive materials is numerously focused on the ptype conjugated polymers which are generally synthesized by polymerization of electron-rich donor and electron-deficient acceptor monomers. Compared to the development of electron-deficient comonomers (acceptor segments), the development of electron-rich donor materials is considerably flourishing. Forced planarization by covalently fastening adjacent aromatic and heteroaromatic subunits leads to the formation of ladder-type conjugated structures which are capable of elongating effective conjugation, reducing the optical bandgap, promoting intermolecular pi-pi interactions and enhancing intrinsic charge mobility. In this review, we will summarize the recent progress on the development of various well-defined new ladder-type conjugated materials. These materials serve as the superb donor monomers to prepare a range of donor-acceptor semiladder copolymers with sufficient solution-processability for solar cell applications.
"Optimal detection angle in sub-diffraction resolution photothermal microscopy: application for high sensitivity imaging of biological tissues": reply
(2015-03-09)
Miyazaki, Jun
;
Tsurui, Hiromichi
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Kawasumi, Koshi
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Kobayashi, Takayoshi
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電子物理學系
The differences between our model and existing models are rationalized in terms of the experimental conditions. The theory in [Opt. Express 22(16), 18833-18842 (2014)] is applicable when the temperature increase is moderate (similar to 1 K) and the spatial extend of refractive index being modulated is comparable to or smaller than the wavelength, which are in accordance with our experiment. (C) 2014 Optical Society of America
Charge transport in amorphous Hf0.5Zr0.5O2
(2015-03-09)
Islamov, D. R.
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Perevalov, T. V.
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Gritsenko, V. A.
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Cheng, C. H.
;
Chin, A.
In this study, we demonstrated experimentally and theoretically that the charge transport mechanism in amorphous Hf0.5Zr0.5O2 is phonon-assisted tunneling between traps like in HfO2 and ZrO2. The thermal trap energy of 1.25 eV and optical trap energy of 2.5 eV in Hf0.5Zr0.5O2 were determined based on comparison of experimental data on transport with different theories of charge transfer in dielectrics. A hypothesis that oxygen vacancies are responsible for the charge transport in Hf0.5Zr0.5O2 was discussed. (C) 2015 AIP Publishing LLC.
Method of manufacturing semiconductor device
(2015-03-10)
Liu Po-Tsun
;
Wang Wei-Ya
;
Teng Li-Feng
The present invention provides a method of manufacturing a semiconductor device. The method at least comprises the following steps. First, the semiconductor device, which comprises a gate, a gate dielectric layer, an active layer, a source and a drain, is manufactured. However, the semiconductor device has a plurality of defects, and the active layer is a metal oxide thin film. After annealing the semiconductor device, it will be transferred into a chamber. A final step of injecting a supercritical fluid carried with a co-solvent into the chamber is then performed to modify the abovementioned defects.
Apparatus for identifying falls and activities of daily living
(2015-03-10)
Yang Bing-Shiang
;
Wang Chih-Chung
;
Liao Sain-Ting
The present invention provides and apparatus for distinguishing falls from activities of daily living (ADLs). First, the human movements and muscle activities would be obtained by an electromyography measuring unit and/or an inertia measuring unit to record ADLs, and falls would be distinguished from ADLs to trigger the protecting devices in time to prevent or decrease injury. In addition, the apparatus would be preset for different operational conditions to adapt different users by a setting unit to increase accuracy. Finally, the moving distance and the direction of the user would be obtained by the electromyography measuring unit and/or the inertia measuring unit to obtain the location thereof in an interior space.
Overexpression of an Outer Membrane Protein Associated with Decreased Susceptibility to Carbapenems in Proteus mirabilis
(2015-03-10)
Tsai, Yi-Lin
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Wang, Min-Cheng
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Hsueh, Po-Ren
;
Liu, Ming-Che
;
Hu, Rouh-Mei
Proteus mirabilis isolates commonly have decreased susceptibility to imipenem. Previously, we found P. mirabilis hfq mutant was more resistant to imipenem and an outer membrane protein (OMP) could be involved. Therefore, we investigated the role of this OMP in carbapenem susceptibility. By SDS-PAGE we found this OMP (named ImpR) was increased in hfq mutant and LC-MS/MS revealed it to be the homologue of Salmonella YbfM, which is a porin for chitobiose and subject to MicM (a small RNA) regulation. We demonstrated that ImpR overexpression resulted in increased carbapenem MICs in the laboratory strain and clinical isolates. Chitobiose induced expression of chb (a chitobiose utilization operon). Real-time RT-PCR and SDS-PAGE were performed to elucidate the relationship of hfq, impR, chb and MicM in P. mirabilis. We found MicM RNA was decreased in hfq mutant and chbBC-intergenic region (chbBC-IGR) overexpression strain (chbIGRov), while impR mRNA was increased in hfq mutant, micM mutant and chbIGRov strain. In addition, mutation of hfq or micM and overexpression of chbBC-IGR increased ImpR protein level. Accordingly, chitobiose made wild-type have higher levels of ImpR protein and are more resistant to carbapenems. Hfq- and MicM-complemented strains restored wild-type MICs. Mutation of both impR and hfq eliminated the increase in carbapenem MICs observed in hfq mutant and ImpR-complementation of hfq/impR double mutant resulted in MICs as hfq mutant, indicating that the ImpR-dependent decreased carbapenem susceptibility of hfq mutant. These indicate MicM was antisense to impR mRNA and was negatively-regulated by chbBC-IGR. Together, overexpression of ImpR contributed to the decreased carbapenem susceptibility in P. mirabilis.
Silicon-based dual ARROW power splitters with remote coupling
(2015-03-10)
Hsu, Hsin-Feng
;
Hsu, Ming-Shun
;
Lu, Ming-Feng
;
Huang, Yang-Tung
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生物科技學系
In this research, Si-based power splitters based on dual antiresonant reflecting optical waveguides (ARROW) with remote coupling by a separation distance of 30 mu m were designed and realized. Characterization of the power splitters with different lengths of the coupling region was performed. Measurement characteristics of fabricated devices with the propagation losses lower than 1.90 dB/cm and the imbalances lower than 0.60 dB show that our dual ARROW power splitters can be efficiently realized. (C) 2015 Optical Society of America