Browsing by Issue Date, starting with "2010-02-01"

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Improved crystal quality and performance of GaN-based light-emitting diodes by decreasing the slanted angle of patterned sapphire
(2010-02-01)
Cheng, Ji-Hao
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Wu, YewChung Sermon
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Liao, Wei-Chih
;
Lin, Bo-Wen
;
材料科學與工程學系
Periodic triangle pyramidal array patterned sapphire substrates (PSSs) with various slanted angles were fabricated by wet etching. It was found beside normal wurtzite GaN, zinc blende GaN was found on the sidewall surfaces of PSS. The crystal quality and performance of PSS-LEDs improved with decrease in slanted angle from 57.4 degrees to 31.6 degrees. This is because most of the growth of GaN was initiated from c-planes. As the growth time increased, GaN epilayers on the bottom c-plane covered these pyramids by lateral growth causing the threading dislocation to bend toward the pyramids.
Effect of Practice on Stepping Movements Onto Laterally Compliant Raised Structures: Age Differences in Healthy Males
(2010-02-01)
Yang, Bing-Shiang
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Ashton-Miller, James A.
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機械工程學系
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Department of Mechanical Engineering
Objective: The aim of this study was to examine effects of practice and age on step-up movements onto raised structures. Background: Falls from laterally compliant structures, such as stepladders, often cause injuries in elderly persons. Although age differences in step-up movements onto raised structures with unexpected structural compliance have been reported, practice effects of such movement control have not been investigated. Method: Movement behavior of 20 healthy adults (10 young and 10 older males) was measured while they stepped up onto a raised structure with no compliance (i.e., rigid) (C(0)), a small amount of mediolateral compliance (C(1)), or greater mediolateral compliance (C(2)). The conditions C(0), C(1), and C(2) were presented in three sets of six fixed-order trials with step-up movements performed at a comfortable speed. Practice effects in step-up behavior were examined by comparing data within each trial block with the use of repeated-measures ANOVA. Results: Practice significantly reduced the stepping duration (Ts) needed to complete the step-up movement (p < .001). With practice, older males reduced their lateral oscillations 26% to 40% for C(1) and C(2), whereas the corresponding results for young males lay between 8% and 17%, respectively. The age difference in Ts decreased across six consecutive trials but remained significant, especially on the structure with greater compliance. Conclusion: With practice, both young and elderly men adapted their stepping behavior to the presence of lateral structural compliance, but it is noteworthy from a fall-injury prevention perspective that the elderly men required more trials to do so. Application: Designers and users of raised structures, such as stepladders, should be aware of the age difference of people using such structures and should minimize the structure compliance when designing them.
Ab Initio Chemical Kinetics for the NH(2) + HNO(x) Reactions, Part III: Kinetics and Mechanism for NH(2) + HONO(2)
(2010-02-01)
Xu, Shucheng
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Lin, M. C.
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應用化學系分子科學碩博班
;
Institute of Molecular science
The kinetics and mechanism for the reaction of NH(2) with HONO(2) have been investigated by ab initio calculations with rate constant prediction. The potential energy surface of this reaction has been computed by single-point calculations at the CCSD(T)/6311 +G(3df, 2p) level based on geometries optimized at the B3LYP/6-311 +G(3df, 2p) level. The reaction producing the primary products, NH(3) + NO(3), takes place via a precursor complex, H(2)N center dot center dot center dot HONO(2) with an 8.4-kcal/mol binding energy. The rate constants for major product channels in the temperature range 200-3000 K are predicted by variational transition state or variational Rice-Ramsperger-Kassel-Marcus theory. The results show that the reaction has a noticeable pressure dependence at T < 900 K. The total rate constants at 760 Torr Ar-pressure can be represented by k(total) = 1.71 x 10(-3) x T(-3.85) exp(-96/T) cm(3) molecule(-1) s(-1) at T = 200-550 K, 5.11 X 10(-23) x T(+3.22) exp(70/T) cm(3) molecule(-1) s(-1) at T = 550-3000 K. The branching ratios of primary channels at 760 Torr Ar-pressure are predicted: k(1) producing NH(3) + NO(3) accounts for 1,00-0,99 in the temperature range of 200-3000 K and k(2) + k(3) producing H(2)NO + HONO accounts for less than 0.01 when temperature is more than 2600 K. The reverse reaction, NH(3) + NO(3) -> NH(2) + HONO(2) shows relatively weak pressure dependence at P < 100 Torr and T < 600 K due to its precursor complex, NH(3)center dot center dot center dot O(3)N with a lower binding energy of 1.8 kcal/mol, The predicted rate constants can be represented by k(-1) = 6.70 x 10(-24) x T(+3.58) exp(-850/T) cm(3) molecule(-1) s(-1) at T = 200-3000 K and 760 Torr N(2) pressure, where the predicted rate at T = 298 K, 2.8 x 10(-16) cm(3) molecule(-1) s(-1) is in good agreement with the experimental data. The NH(3) + NO(3) formation rate constant was found to be a factor of 4 smaller than that of the reaction OH + HONO(2) producing the H(2)O + NO(3) because of the lower barrier for the transition state for the OH + HONO(2) (C) 2009 Wiley Periodicals, Inc. Int J Chem Kinet 42: 69-78, 2010
絕對延遲時間產生裝置
(2010-02-01)
李鎮宜
;
游瑞元
;
余建螢
;
陳俊廷
一種絕對延遲時間產生裝置，由一製程供壓溫度(process-voltage-temperature；PVT)偵測裝置與一延遲時間產生器所構成。PVT偵測裝置包含複數組延遲模組與訊號相位/頻率控制模組，且各該延遲模組復包含對照單元與參照單元，此對照單元與參照單元在延遲特性上對PVT有相異的敏感度。各該延遲模組係用以比對原始訊號分別通過對照單元與參照單元所產生的相位或頻率差異，進而產生各該延遲模組的延遲參數，而訊號相位/頻率控制模組係用以接收並比對各該延遲參數，以標定該絕對延遲時間產生裝置的外部環境PVT狀態，進而控制與校正此延遲時間產生器，產生一精準的絕對延遲時間。透過上述絕對延遲時間產生裝置，受到不同的PVT(process-voltage-temperature)影響下，分析各該延遲模組的延遲參數，以標定當前PVT條件對該絕對延遲時間產生裝置造成的延遲情況，產生精準的絕對延遲時間，可進而產生精準頻率。在PVT改變的情況下，依然能夠保持穩定的準確度。
A Full duplex radio-over-fiber link with Multi-level OFDM signal via a single-electrode MZM and wavelength reuse with a RSOA
(2010-02-01)
Jiang, Wen-Jr
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Lin, Chun-Ting
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Shih, Po-Tsung
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Chen, Jason (Jyehong)
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Peng, Peng-Chun
This work demonstrates the feasibility of a full duplex Radio-over-fiber (RoF) link employing multi-level OFDM signal via a single-electrode Mach-Zehnder modulator and wavelength reuse for uplink utilizing a reflective semiconductor optical amplifier (RSOA). A High spectral efficiency 5-Gb/s 16-QAM OFDM signal with frequency multiplication for the RoF downstream link is demonstrated, and negligible penalty is achieved after 25-km standard single mode fiber transmission. Furthermore, wavelength reuse for a 1.25-Gb/s OOK signal via a RSOA for the upstream link is also demonstrated with a receiver penalty of less than 0.5 dB following 25-km SMF transmission. (C) 2010 Optical Society of America
用於通道解碼系統之候選人清單擴增裝置及其方法
(2010-02-01)
張錫嘉
;
廖彥欽
本發明係揭露一種可應用於多輸入多輸出通道解碼系統之候選人清單擴增裝置及其擴增方法。本發明所提出之路徑擴增方法可擴增候選人清單中之路徑以便於系統用於計算可靠度資訊,另一方面,本發明另提供一額外之校正項來動態補償可靠度資訊之準確度,進而大幅提昇多輸入多輸出系統之偵錯能力以及整體效能。
Scalar-tensor theory and the anisotropic perturbations of the inflationary universe
(2010-02-01)
Kao, W. F.
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物理研究所
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Institute of Physics
Inflationary higher derivative scalar-tensor theory is analyzed in this paper in a de Sitter background space. A useful model-independent formula of the Friedmann equation is derived and used to study the stability problem associated with the anisotropic perturbations of the inflationary solution. The stability conditions of the de Sitter solution are derived for a general class of models. For a simple demonstration, an induced gravity model is considered in this paper for the effects of the higher derivative interactions including a cubic term.
EFFICIENT VERIFIER-BASED AUTHENTICATED KEY AGREEMENT PROTOCOL FOR THREE PARTIES
(2010-02-01)
Wu, Tzong-Sun
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Lin, Han-Yu
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Hsu, Chien-Lung
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Chang, Kuo-Yi
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資訊工程學系
Authenticated key agreement protocols for three parties enable two clients to establish a secure communication channel through an authentication server. Generally speaking, there are two approaches to achieve this purpose. One is to issue a common session key for both clients by the key distribution center (KDC). The other is to use public key cryptosystems and the encrypted key exchange (EKE) protocol to encrypt the transmitted messages and then further derive a common session key. Recently, lots of researches on authenticated key agreement protocol for three parties use the servers public key to ensure the security of transmitted messages. Yet, the approach obviously has some drawbacks, such as increasing the cost of key management for each client. Hence, the demand for secure protocols without the server's public key comes out. In this paper, we propose an efficient verifier-based authenticated key agreement for three parties. The proposed protocol can resist the password guessing attack and other existential attacks. Moreover, compared with previous works, the proposed one also has lower computational costs.
Single-Longitudinal-Mode Erbium-Doped Fiber Laser with Novel Scheme Utilizing Fiber Bragg Grating inside Ring Cavity
(2010-02-01)
Yeh, C. H.
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Chow, C. W.
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光電工程學系
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Department of Photonics
In this paper, we experimentally investigate a single-longitudinal-mode (SLM) S-band erbium-doped fiber (EDF) laser with dual-ring scheme using a S-band fiber Bragg grating (FBG) inside the gain cavity to restrict the lasing mode. The proposed laser is constructed by two-ring cavities serving as the mode filters. The FBG inside the proposed laser scheme can retrieve the SLM operation. Moreover, the output performance of the proposed fiber laser is also analyzed and discussed.
The monotone boundary property and the full coverage property of confidence intervals for a binomial proportion
(2010-02-01)
Wang, Hsiuying
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交大名義發表
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National Chiao Tung University
The methodology for deriving the exact confidence coefficient of some confidence intervals for a binomial proportion is proposed in Wang [2007. Exact confidence coefficients of confidence intervals for a binomial proportion. Statist. Sinica 17, 361-368]. The methodology requires two conditions of confidence intervals: the monotone boundary property and the full coverage property. In this paper, we show that for some confidence intervals of a binomial proportion, the two properties hold for any sample size. Based on results presented in this paper, the procedure in Wang [2007. Exact confidence coefficients of confidence intervals for a binomial proportion. Statist. Sinica 17, 361-368] can be directly used to calculate the exact confidence coefficients of these confidence intervals for any fixed sample size. (C) 2009 Elsevier B.V. All rights reserved.
Electrocatalytic activity of Pt nanoparticles electrodeposited on amorphous carbon-coated silicon nanocones
(2010-02-01)
Tiwari, Jitendra N.
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Pan, Fu-Ming
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Chen, Te-Ming
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Tiwari, Rajanish N.
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Lin, Kun-Lin
This study pulse-electrodeposits Pt nanoparticles on amorphous carbon-coated silicon nanocones (ACNCs) and explores them as the electrocatalyst for methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) for direct methanol fuel cell applications. The work prepares silicon nanocones on the Si wafer using porous anodic aluminum oxide as the template and then deposits the amorphous carbon layer on the nanocones by microwave plasma chemical vapor deposition. According to Raman scattering and X-ray photoelectron spectroscopies (XPS), the surface of the ACNC support is composed of a nanocrystalline graphitic structure. and rich in oxygen-containing adspecies. The Pt nanoparticles pulse-electrodeposited on the highly ordered ACNC support disperses well with a large electrocatalytic surface area. The Pt/ACNC electrode exhibits excellent electrocatalytic activity and stability toward both MOR and ORR. This study suggests the abundant oxygen-containing surface species and the nanometer size of the Pt catalyst as the two major factors enhancing electrocatalytic performance of Pt/ACNC electrode. The XPS Study suggests the occurrence of charge transfer from pi-sites of the graphitic Structure to the Pt nanoparticle, thereby improving the electrochemical stability of the electrode. (C) 2009 Elsevier B.V. All rights reserved.
A unified model for detecting efficient and inefficient outliers in data envelopment analysis
(2010-02-01)
Chen, Wen-Chih
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Johnson, Andrew L.
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工業工程與管理學系
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Department of Industrial Engineering and Management
Data envelopment analysis(DEA) uses extreme observations to identify superior performance, making it vulnerable to outliers. This paper develops a unified model to identify both efficient and inefficient outliers in DEA. Finding both types is important since many post analyses, after measuring efficiency, depend on the entire distribution of efficiency estimates. Thus, outliers that are distinguished by poor performance can significantly alter the results. Besides allowing the identification of outliers, the method described is consistent with a relaxed set of DEA axioms. Several examples demonstrate the need for identifying both efficient and inefficient outliers and the effectiveness of the proposed method. Applications of the model reveal that observations with low efficiency estimates are not necessarily outliers. In addition, a strategy to accelerate the computation is proposed that can apply to influential observation detection. (C) 2009 Elsevier Ltd. All rights reserved.
A new tool linking human cytomegalovirus drug resistance mutations to resistance phenotypes
(2010-02-01)
Chevillotte, Meike
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von Einem, Jens
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Meier, Benjamin M.
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Lin, Feng-Mao
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Kestler, Hans A.
Drug resistant strains of human cytomegalovirus (HCMV) in patients at risk may increasingly develop into a problem in the clinical setting. Genotypic resistance testing is becoming the method of choice, but requires previous phenotypic characterisation of each newly found mutation. In order to facilitate the interpretation of the patient's CMV sequence data, a web-based search tool was generated that links the sequence to a database containing all published UL97 (protein kinase) and UL54 (DNA polymerase) mutations and corresponding antiviral drug susceptibility phenotypes. It is reasonable to assume that HCMV drug resistance testing will provide relevant data for an adjustment of therapy and on prognosis of clinical outcome. HCMV drug susceptibility testing will become even more important once new drugs will be available for therapy allowing a wider choice of antiviral agents to treat HCMV disease. These topics will also play a pivotal role for optimising antiviral therapy of HCMV- and other viral diseases. (C) 2009 Elsevier B.V. All rights reserved.
Synthesis of Thermal-Stable and Photo-Crosslinkable Polyfluorenes for the Applications of Polymer Light-Emitting Diodes
(2010-02-01)
Wang, Pei-Hsuan
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Ho, Ming-Shou
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Yang, Sheng-Hsiung
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Chen, Kuei-Bai
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Hsu, Chain-Shu
Three polyfluorene derivatives which have oxetane-containing phenyl group at C-9 position were synthesized via the palladium-catalyzed Suzuki-coupling reaction. The synthesized polymers PFB, PFG, and PFR emit blue, green, and red light, respectively. A double-layer device with the configuration of ITO/PEDOT/polymer/Ca/Al using PFB as the active layer showed a threshold voltage of 5 V, a maximum brightness of 2030 cd/m(2), and a maximum current efficiency of 0.35 cd/A. Using PFG as the active layer, the device exhibited a threshold voltage of 6 V, a maximum brightness of 6447 cd/m(2), and a maximum current efficiency of 1.27 cd/A. Using PFR as the active layer, the device showed a threshold voltage of 4 V, a maximum brightness of 2135 cd/m(2), and a maximum current efficiency of 0.16 cd/A. Better electroluminescent performance was also found based on different design of device structures. Due to photo-crosslinking property of oxetane groups, the UV-exposed thin films are insoluble in common organic solvents. A device comprised of blue, green, and red-emissive pixels was successfully fabricated by spin-coating and photo-lithographic processes. In addition, a white light-emitting device with CIE coordinate of (0.34, 0.33) was achieved by blending PFR into a host material PFB as the active layer. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 516-524, 2010
Carrier density dependent electric transport of serially connected two quantum point contacts
(2010-02-01)
Liu, K. M.
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Lin, H. I.
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Umansky, V.
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Hsu, S. Y.
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電子物理學系
We have measured the electric transport of double quantum point contacts in series at low temperatures. Two pairs of metal gates are placed longitudinally and sequentially with an edge-to-edge distance of 600 nm. They are used to form two quantum point contacts in a GaAs/Al(x)Ga(1-x)As heterostructure. Isolating from an insulating layer, a top gate is also fabricated on top of the quantum point contacts to modify the electron densities in the quantum point contacts and the two dimensional electron gas as well. The transport is characterized by the direct transmission probability T(d) which represents the portions of electrons travelling ballistically from one quantum point contact to the other. Our results show that the parameter T(d) decreases with decreasing carrier density. The transport is partially adiabatic in high 20 electron densities and transits to completely ohmic regimes in low densities. Because of the correlation between the coherence length and transmission probability, we attribute the result to the reduction of the coherence length and mean free path in the unconstricted electron gas between quantum point contacts. (C) 2010 Elsevier B.V. All rights reserved.
ITRI-WiMAXT: A WiMAX conformance testing tool
(2010-02-01)
Lee, Hsin-Yi
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Lin, Yi-Bing
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Liang, Ching-Feng
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Huang, Shiang-Ming
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資訊工程學系
The WiMAX Forum certifies and promotes the compatibility and interoperability of broadband wireless products where many testcases need to be developed for WiMAX procedures. In this paper, we develop a conformance test tool called ITRI-WiMAXT based on the TTCN-3 specifications. Then we show how WiMAX procedures are tested in ITRI-WiMAXT. Based on ITRI-WiMAXT, we have proposed several test procedures accepted by the WiMAX Forum. Copyright (C) 2009 John Wiley & Sons, Ltd.
EFFECTS OF TEMPORALLY DIFFERENTIAL FARES ON TAIPEI METRO RIDERS' MODE AND TIME-OF-DAY CHOICES
(2010-02-01)
Lan, Lawrence W.
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Lee, Hsiang-Yi
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Wen, Chieh-Hua
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交大名義發表
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National Chiao Tung University
Introducing temporally differential fares to shift a portion of peak-hour demand to off-peak hours shows promise in mitigating the overcrowded Taipei Metro system during peak hours. This study looked to elucidate how Taipei Metro riders would change their times of travel or use of other travel modes, should peak-hour surcharge or off-peak discount fare schemes be introduced Multinomial logit and nested lop models were employed to depict the riders' stated behavior, in terms of arrival times and mode choices, within the context of a scenario involving tested differential fare levels Results showed that introducing temporally differential fares would prompt a portion of peak-hour Metro riders to shift to off-peak periods, or even to choose the use of other modes The Metro riders were sensitive to the tested differential fare levels, especially the peak-hour surcharge The afternoon riders were more sensitive to proposed fare changes than the morning riders To implement the temporally differential fares successfully within the Metro system, it is suggested that peak hours be carefully designated and that peak-hour riders be clearly distinguished from off-peak riders
Reprioritization of failures in a silane supply system using an intuitionistic fuzzy set ranking technique
(2010-02-01)
Chang, Kuei-Hu
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Cheng, Ching-Hsue
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Chang, Yung-Chia
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工業工程與管理學系
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Department of Industrial Engineering and Management
Most of the current failure mode, effects, and criticality analysis (FMECA) methods use the risk priority number (RPN) value to evaluate the risk of failure. However, the traditional RPN methodology has been criticized to have several shortcomings. These shortcomings are addressed in this paper. Therefore, an efficient and simplified algorithm to evaluate the risk of failure is needed. This paper proposes a new approach, which utilizes the intuitionistic fuzzy set ranking technique for reprioritization of failures in a system FMECA. The proposed approach has two major advantages: (1) it resolves some of the shortcomings of the traditional RPN method, and (2) it provides an evaluation of the redundancy place, which can assist the designer in making correct decisions to make a safer and more reliable product design. In numerical verification, an FMECA of a silane supply system is presented as a numerical example. After comparing results from the proposed method and two other approaches, this research found that the proposed approach can reduce more duplicate RPN numbers and get a more accurate, reasonable risk ranking.
Emission color variation of (Ba,Sr)(3)BP3O12:Eu2+ phosphors for white light LEDs
(2010-02-01)
Kuo, Te-Wen
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Liu, Wei-Ren
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Chen, Teng-Ming
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應用化學系
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Department of Applied Chemistry
A series of alkaline earth borophosphate phosphors, (Ba,Sr)(3)BP3O12 doped with Eu2+ ions, were synthesized by a solid state reaction. Two emission bands at 465 nm and 520 nm were attributed to the f-d transitions of doped Eu2+ ions occupying in two different cation sites in host lattices and emission color variation was observed by substituting the M2+ sites, which was rationalized in terms of two competing factors of the crystal field strength and bond covalence. Green and bluish-white pc-LEDs were fabricated by combination of a 370 nm near-UV chip and composition-optimized Ba3BP3O12:Eu2+ and (Ba,Sr)(3)BP3O12:Eu2+ phosphors, respectively. The series of phosphors may serve as a promising green and bluish-white luminescent materials used in fabrication of near UV-based white pc-LEDs. (C) 2010 Optical Society of America
數位延遲線與其應用
(2010-02-01)
李鎮宜
;
游瑞元
;
陳俊廷
一種數位延遲線，以數個滯後基礎的遲滯單元串聯組成，滯後基礎的遲滯單元可以相同或相異，且具有一反相器模式與一遲滯模式。遲滯單元的一延遲時間與一解析度則可由反相器模式與該遲滯模式之時間差來構成。當應用於數位鎖相迴路中時，可有效減少佔用面積與功率消耗。