Browsing by Issue Date, starting with "2011-10-01"

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TiO(2-x) nanoparticles synthesized using He/Ar thermal plasma and their effectiveness on low-concentration mercury vapor removal
(2011-10-01)
Tsai, Cheng-Yen
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Hsi, Hsing-Cheng
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Bai, Hsunling
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Fan, Kuo-Shuh
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Chen, Chienchih
Oxygen-vacant titanium dioxide (TiO(2-x) ) nanoparticles were synthesized using thermal plasma as a heating source at various applied plasma currents and He/Ar ratios. Samples with diverse characteristics were developed and the mercury removal effectiveness was subsequently evaluated. TiO(2) nanoparticles possessing high purity and uniform particle sizes were successfully synthesized using metal titanium and O(2) as precursors and Ar as plasma gas. TiO(2-x) in anatase phase with a particle size at 5-10 nm was formed at the He/Ar volume ratio of 25/75. Further increasing the He/Ar ratio elevated the plasma temperature, causing the tungsten to melt, vaporize from the cathode, and then dope into the formed TiO(2) nanoparticles. The doped W appeared to inhibit the growth of nanoparticles and decrease the crystallinity of formed anatase. The effectiveness of oxygen-vacant sites on Hg(0) removal under the visible light circumstance was confirmed. Hg(0) removal by the TiO(2-x) nanoparticles was enhanced by increasing the O(2) concentration. However, moisture reduced Hg(0) capture, especially when light irradiation was applied. The reduction in Hg(0) capture may be resulted from the competitive adsorption of H(2)O on the active sites of TiO(2-x) with Hg(0) and transformed Hg(2+).
High-power 10-GHz self-mode-locked Nd:LuVO(4) laser
(2011-10-01)
Huang, Y. J.
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Liang, H. C.
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Chen, Y. F.
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Zhang, H. J.
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Wang, J. Y.
We report on a high-power diode-end-pumped self-mode-locked Nd:LuVO(4) laser with the pulse repetition rate up to 9.52 GHz for the first time. The large third-order nonlinearity of the Nd:LuVO(4) crystal is exploited to efficiently achieve a fairly stable self-mode-locked operation without any additional components. The detailed characteristics of the compact efficient self-mode-locked laser are experimentally investigated and theoretically analyzed. With the incident pump power of 2.6 W, the average output power up to 0.54 W is generated with the pulse width of 7.9 ps at the pulse repetition rate of 9.52 GHz.
A practical authentication protocol with anonymity for wireless access networks
(2011-10-01)
Chen, Yen-Cheng
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Chuang, Shu-Chuan
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Yeh, Lo-Yao
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Huang, Jiun-Long
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資訊工程學系
The use of anonymous channel tickets was proposed for authentication in wireless environments to provide user anonymity and to probably reduce the overhead of re-authentications. Recently, Yang et al. proposed a secure and efficient authentication protocol for anonymous channel in wireless systems without employing asymmetric cryptosystems. In this paper, we will show that Yang et al.'s scheme is vulnerable to guessing attacks performed by malicious visited networks, which can easily obtain the secret keys of the users. We propose a new practical authentication scheme not only reserving the merits of Yang et al.'s scheme, but also extending some additional merits including: no verification table in the home network, free of time synchronization between mobile stations and visited networks, and without obsolete anonymous tickets left in visited networks. The proposed scheme is developed based on a secure one-way hash function and simple operations, a feature which is extremely fit for mobile devices. We provide the soundness of the authentication protocol by using VO logic. Copyright (C) 2010 John Wiley & Sons, Ltd.
Plasmonic Green Nanolaser Based on a Metal-Oxide-Semiconductor Structure
(2011-10-01)
Wu, Chen-Ying
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Kuo, Cheng-Tai
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Wang, Chun-Yuan
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He, Chieh-Lun
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Lin, Meng-Hsien
Realization of smaller and faster coherent light sources is critically important for the emerging applications in nanophotonics and information technology. Semiconductor lasers are arguably the most suitable candidate for such purposes. However, the minimum size of conventional semiconductor lasers utilizing dielectric optical cavities for sustaining laser oscillation is ultimately governed by the diffraction limit (similar to(lambda/2n)(3) for three-dimensional (3D) cavities, where lambda is the free-space wavelength and n is the refractive index). Here, we demonstrate the 3D subdiffraction-limited laser operation in the green spectral region based on a metal oxide semiconductor (MOS) structure, comprising a bundle of green-emitting InGaN/GaN nanorods strongly coupled to a gold plate through a SiO(2) dielectric nanogap layer. In this plasmonic nanocavity structure, the analogue of MOS-type "nanocapacitor" in nanoelectronics leads to the confinement of the plasmonic field into a 3D mode volume of 8.0 x 10(-4) mu m(3) (similar to 0.14(lambda/2n)(3)).
Drag Coefficient of a Spherical Particle Attached on the Flat Surface
(2011-10-01)
Liu, Chun-Nan
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Chien, Chih-Liang
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Lo, Chu-Chun
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Lin, Guan-Yu
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Chen, Sheng-Chieh
The previous analytical solution for the drag coefficient (C(d)) for a spherical particle attached on the flat surface, which was derived by O'Neill (1968), is only valid in the creeping flow conditions. It is important to extend O'Neill's formula to cover a wide range of particle Reynolds number (Re(p)). In this study, the drag coefficient was calculated numerically to cover Re(p) from 0.1 to 250. For a particle suspended in the air, an empirical drag coefficient exists, which is defined as C(d) = f x 24/Re(p), where f is a correction factor depending on Re(p). The applicability of the correction factor f for O'Neill's analytical equation for the spherical particle attached on the flat surface for Re(p) = 0.1 to 250 was examined in this study.
CTAP-Minimized Scheduling Algorithm for Millimeter-Wave-Based Wireless Personal Area Networks
(2011-10-01)
Chao, Hsi-Lu
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Hsu, Ming-Pei
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資訊工程學系
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Department of Computer Science
Beamforming is used in IEEE 802.15.3c networks to avoid high propagation attenuation and path loss and improve the overall system throughput by exploiting spatial channel reuse. In this paper, we introduce design challenges of scheduling in beamforming-enabled IEEE 802.15.3c networks. These challenges include positioning, axis alignment, and interference relation verification. We then propose a joint design of axis alignment, positioning, and scheduling. The objectives of the proposed joint design are to reduce the consumed channel time, increase the degree of spatial channel reuse, and improve the channel utilization. For positioning, we define and prove a sufficient condition for anchor selection to improve positioning accuracy. The designed channel time allocation period (CTAP)-minimized scheduling algorithm is depicted as a two-layer flow graph, and it consists of the following three phases: 1) layer-1 edge construction; 2) layer-2 edge construction; and 3) scheduling. Through the observation of transmission and reception beams, we define a rule to verify the interference relation of two flows. In addition, given correct topology information, we prove that CTAP-minimized uses the least time to serve all data flows. We evaluate and compare our algorithm with existing approaches through simulations. The observed performance metrics include utilized channel time, system throughput, scheduling efficiency, and spatial channel reuse degree. The results show that CTAP-minimized performs well and achieves its objectives.
Growth of CuInSe2 and In2Se3/CuInSe2 Nano-Heterostructures through Solid State Reactions
(2011-10-01)
Hsin, Cheng-Lun
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Lee, Wei-Fan
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Huang, Chi-Te
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Huang, Chun-Wei
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Wu, Wen-Wei
In2Se3 is an essential phase change material and CuInSe2 is the fundamental basis of the copper-indium-gallium-diselenide (CIGS) solar energy material. In this paper, we demonstrate the feasibility to transform the phase change material to the solar energy material via the solid state reaction. The In2Se3 nanobelts (NBs) were synthesized via the vapor-liquid-solid mechanism. The chemical composition and the optical properties were investigated by energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and reflectance and photoluminescence spectra. In the in situ observation of the solid state reaction with Cu to form the CuInSe2 NBs with ultrahigh vacuum transmission electron microscopy, we observed the In2Se3/CuInSe2 transformation at atomic scale in real time. The progression of the atomic layer at the interface provided the pertinent information on the kinetic mechanism. In2Se3/CuInSe2 nano-heterostructures were also obtained in the present investigation. The approach to the CIGS nanosolar cell was also proposed. This study shall be beneficial in the development of high-performance nanowire solar cells and nanodevices with In2Se3/CuInSe2 nano-heterostructures.
Large Scale Single-Crystal Cu(In,Ga)Se-2 Nanotip Arrays For High Efficiency Solar Cell
(2011-10-01)
Liu, Chin-Hung
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Chen, Chia-Hsiang
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Chen, Szu-Ying
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Yen, Yu-Ting
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Kuo, Wei-Chen
In this paper, we demonstrated direct formation of large area Cu(In,Ga)Se-2, nanotip arrays (GIGS NTRs) by using one step Ar+ milling process without template. By controlling milling time and incident angles, the length of CIGS NTRs with adjustable tilting orientations can be precisely controlled. Formation criteria of these CIGS NTRs have been discussed in terms of surface curvature, multiple components, and crystal quality, resulting in a highly anisotropic milling effect. The CIGS NTRs have very low reflectance <0.1% at incident wavelengths between 300 to 1200 nm. Open circuit voltage and short circuit current of CIGS NTRs solar cell were measured to be similar to 390 mV and similar to 22.56 mA/cm(2), yielding the filling factor and the efficiency of 59 and 5.2%, respectively. In contrast to CIGS thin film solar cell with efficiency of 3.2%, the nanostructured CIGS NTRs can have efficiency enhancement of similar to 160% due to the higher light absorption ability because of the nanostructure. The merits of current approach include the latest way via template-free direct creating process of nanostructured CIGS NTRs with controllable dimensionality and large scale production without postselenization process.
台商對外投資大陸之區位順序選擇行為：層級貝氏順序羅吉斯迴歸模型之應用
(2011-10-01)
陳靜怡
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Ching-I Chen
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Institute of Business and Management
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經營管理研究所
本研究根據台灣廠商至大陸投資的區位順序選擇行爲，驗證區位優勢理論及國際化程序的觀點。典型的對外投資區位選擇研究係以區位特性做爲自變數，應變數則可分爲兩類：投資地點的總合投資量及廠商之投資地點選擇；前者無法探討個別廠商的決策行爲，後者則不易估計廠商層次的參數估計。因此，本研究根據個別廠商對陸投資地點的先後順序，搭配投資地點的區位優勢（如市場潛力、勞工便宜、交通便利、聚集經濟等）以及投資前置時間，討論廠商之投資區位偏好及學習效果。有別於以平均效果估計爲實證結果的傳統統計模型，本研究建立層級貝氏順序羅吉斯迴歸模型，整合不同分析層次的資料，用以衡量廠商間具異質性的投資偏好結構，並以廠商比例的概念說明研究假說的實證結果，符合資源基礎理論的邏輯。
The dynamic dependence between the Chinese market and other international stock markets: A time-varying copula approach
(2011-10-01)
Wang, Kehluh
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Chen, Yi-Hsuan
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Huang, Szu-Wei
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資訊管理與財務金融系註：原資管所+財金所
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Department of Information Management and Finance
The purpose of this paper is to study the dependence structures between the Chinese market and other major world markets, a reflection of China's increasing integration into the global economy. We used time-varying copula models to show that conditional copulas outperform both unconditional copulas and conventional GARCH models. We consistently found the Chinese market to have the highest levels of dependence, as well as the greatest variability in dependence, with markets in Japan and the Pacific. Our results provide investors interested in the Chinese market with more timely suggestions for portfolio diversification, risk management, and international asset allocation than those derived from static models. (C) 2010 Elsevier Inc. All rights reserved.
Wavefront-based pixel inversion algorithm for generation of subresolution assist features
(2011-10-01)
Yu, Jue-Chin
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Yu, Peichen
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Chao, Hsueh-Yung
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光電工程學系
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Department of Photonics
The generation of subresolution assist features (SRAFs) using inverse-lithography techniques demands extensive computational resources which limits its deployment in advanced CMOS nodes. In this paper, we propose a wavefront-based pixel inversion algorithm to quickly obtain inverse masks with a high aerial image quality. Further assisted by a flexible pattern simplification technique, we present effective SRAF generation and placement based on the calculated inverse mask. The proposed approach can be easily inserted prior to a conventional mask correction flow for subsequent concurrent optimizations of both drawn patterns and SRAFs. The innovative pixel inversion and pattern simplification techniques allow quality mask corrections as produced by inverse lithography while maintaining the convenience of standardized/validated process flows currently used in the industry. (C) 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI:10.1117/1.3663249]
Expression Status of Ribonucleotide Reductase Small Subunits hRRM2/p53R2 as Prognostic Biomarkers in Stage I and II Non-small Cell Lung Cancer
(2011-10-01)
Hsu, Nan-Yung
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Wu, Jeng-Yuan
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Liu, Xiyong
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Yen, Yun
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Chen, Chih-Yi
Overexpression of ribonucleotide reductase M2 (hRRM2) and p53-dependent RR small subunit (p53R2) has been correlated with tumor malignancy and progression in several types of cancer. The aim of this study was to determine the association of p53R2/hRRM2 expression with clinicopathological characteristics of stage I and II non-small cell lung cancer (NSCLC). Immunohistochemistry was conducted on a tissue array that included 92 samples. Correlations between hRRM2 and p53R2 expression and clinicopathological factors, recurrence/metastasis, and outcomes were analyzed. The analyses revealed that there was no correlation between p53R2 expression and clinicopathological factors; hRRM2 was only positively related to poor tumor differentiation (p=0.006). Regarding overall survival during the follow-up period, patients with p53R2+/hRRM2- tumors had the best outcomes (p<0.01). Multivariant Cox analysis revealed that p53R2 (risk=0.232, 95% CI=0.086-0.626, p=0.004) not only served as a prognostic biomarker to predict survival, but also as an independent biomarker to predict disease-free survival (risk=0.545, 95% CI=0.301-0.987, p=0.045) of patients with NSCLC. Therefore, we consider that the expression of p53R2 can be used not only as a biomarker for overall survival, but also as an indicator for tumor recurrence. Based on our finding, p53R2 expression seems more important than that of hRRM2 in prognosis of early-stage lung cancer.
Study of InGaN-Based Light-Emitting Diodes on a Roughened Backside GaN Substrate by a Chemical Wet-Etching Process
(2011-10-01)
Fu, Yi-Keng
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Chen, Bo-Chun
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Fang, Yen-Hsiang
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Jiang, Ren-Hao
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Lu, Yu-Hsuan
The InGaN-based light-emitting diodes (LEDs) with a roughened backside on the N-face surface of GaN substrate were fabricated through a chemical wet-etching process to increase light-extraction efficiency. The stable crystallographic etching planes were formed as the GaN {10 (11) over bar} planes. When the near-ultraviolet and blue LED were operated as a forward current of 20 mA, the output power of LEDs was improved from 13.2 and 19.9 mW to 25.6 and 24.0 mW, respectively. The different enhanced ratio is attributed to the different transmittance as a function of wavelength is caused from hexagonal pyramid on N-face GaN substrate after wet-etching process.
Conditional-Fault Diagnosability of Multiprocessor Systems with an Efficient Local Diagnosis Algorithm under the PMC Model
(2011-10-01)
Lin, Cheng-Kuan
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Kung, Tzu-Liang
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Tan, Jimmy J. M.
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資訊工程學系
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Department of Computer Science
Diagnosis is an essential subject for the reliability of multiprocessor systems. Under the PMC diagnosis model, Dahbura and Masson [12] proposed a polynomial-time algorithm with time complexity O(N(2.5)) to identify all the faulty processors in a system with N processors. In this paper, we present a novel method to diagnose a conditionally faulty system by applying the concept behind the local diagnosis, introduced by Somani and Agarwal [30], and formalized by Hsu and Tan [18]. The goal of local diagnosis is to identify the fault status of any single processor correctly. Under the PMC diagnosis model, we give a sufficient condition to estimate the local diagnosability of a given processor. Furthermore, we propose a helpful structure, called the augmenting star, to efficiently determine the fault status of each processor. For an N-processor system in which every processor has an O(log N) degree, the time complexity of our algorithm to diagnose any given processor is O((log N)(2)), provided that each processor can construct an augmenting star structure of full order in time O((log N)(2)) and the time for a processor to test another one is constant. Therefore, the time totals to O(N(log N)(2)) for diagnosing the whole system.
Proportional-Derivative Unknown Input Observer Design Using Descriptor System Approach for Non-Minimum Phase Systems
(2011-10-01)
Ting, Huan-Chan
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Chang, Jeang-Lin
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Chen, Yon-Ping
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電控工程研究所
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Institute of Electrical and Control Engineering
This paper considers the problem of estimating the state of an MIMO linear system with unknown inputs in the state and output. Through a series of linear transformations in the state and output equations, the original system can be transformed into a descriptor system form. The proposed proportional derivative observer can accurately estimate the system state and avoid the peaking phenomenon. Moreover, the approach developed in this paper does not require the derivatives of the output and can be applied to the system with unstable zeros (with respect to the relation between the output and the unknown input). Finally, our algorithm can prove the valid feasibility and the property of disturbance attenuation through demonstrating a simulation-base example.
A Compact Printed Filtering Antenna Using a Ground-Intruded Coupled Line Resonator
(2011-10-01)
Chuang, Chao-Tang
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Chung, Shyh-Jong
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傳播研究所
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Institute of Communication Studies
A compact printed filtering antenna with high bandedge gain selectivity is presented. Occupying about the same substrate area as a conventional antenna, the proposed structure not only serves as a radiator but also a second-order bandpass filter, with one filter pole provided by a Gamma-shaped antenna and the other by a newly proposed coupled line resonator. High band-edge selectivity is achieved due to two additional stop-band transmission zeros provided by the coupled line resonator. To minimize the required area and reduce the spurious radiation, a coupled line structure composed of a microstrip line and a coplanar waveguide by broadside coupling is adopted and intruded into the Gamma-shaped antenna area. According to the filter specifications, a design procedure for the proposed filtering antenna is depicted in detail. One example at 2.45 GHz with a second-order Chebyshev bandpass filter of 0.1 dB equal-ripple response is tackled. As compared to the conventional Gamma-shaped antenna, the proposed filtering antenna not only possesses a similar antenna gain but also provides better bandedge gain selectivity and flat passband gain response. The measured results, including the S-parameters, total radiated power, and antenna gains versus frequency, have good agreement with the designed ones.
Bipolar Nonlinear Ni/TiO2/Ni Selector for 1S1R Crossbar Array Applications
(2011-10-01)
Huang, Jiun-Jia
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Tseng, Yi-Ming
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Hsu, Chung-Wei
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Hou, Tuo-Hung
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電子工程學系及電子研究所
A bipolar nonlinear selector to suppress the sneak current in the crossbar array has been fabricated using a simple Ni/TiO2/Ni metal-insulator-metal structure. The highly nonlinear current-voltage characteristics are realized by the Schottky emission over the Ni/TiO2 barriers. The series connection with an HfO2-resistive memory device shows reproducible bipolar resistive switching. The maximum array size with at least 10% read margin is projected to exceed megabits. This letter demonstrates the promise of the compact one selector-one resistor (1S1R) cell structure for high-density crossbar array applications.
Sound Synthesis of the Pipa Based on Computed Timbre Analysis and Physical Modeling
(2011-10-01)
Chen, Yi-Huei
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Huang, Chih-Fang
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音樂研究所
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Institute of Music
This paper proposes sounds analysis and a synthesis model for the Chinese plucked string instrument called the pipa, one of the oldest Chinese musical instruments with over 2000 years of history. The pipa comprises four strings with 30 frets and individual pear-shaped body so that it can offer a wide chromatic scale around 3.5 octaves and many kinds of tones. The acoustical properties of this instrument are analyzed according to the recorded tones. The most vital playing techniques are synthesized by using both physical and spectral based models with auxiliary rules. Applying the digital waveguide concept, the pipa model was constructed with digital filters and input excitations. Synthetic results are very similar to the recorded one according to the waveforms and spectra comparison and the statistics of listening tests.
Negative Effect of Glucose on ompA mRNA Stability: a Potential Role of Cyclic AMP in the Repression of hfq in Escherichia coli
(2011-10-01)
Lin, Hsiao-Hsien
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Hsu, Chi-Cheng
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Yang, Chi-Dung
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Ju, Yih-Wei
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Chen, Yi-Pei
Glucose is a carbon source that is capable of modulating the level of cyclic AMP (cAMP)-regulated genes. In the present study, we found that the stability of ompA mRNA was reduced in Escherichia coli when glucose (40 mM) was present in Luria-Bertani (LB) medium. This effect was associated with a low level of cAMP induced by the glucose. The results were confirmed with an adenylyl cyclase mutant with low levels of cAMP that are not modulated by glucose. Northern blot and Western blot analyses revealed that the host factor I (Hfq) (both mRNA and protein) levels were downregulated in the presence of cAMP. Furthermore, we showed that a complex of cAMP receptor protein (CRP) and cAMP binds to a specific P3(hfq) promoter region of hfq and regulates hfq expression. The regulation of the hfq gene was confirmed in vivo using an hfq-deficient mutant transformed with an exogenous hfq gene containing the promoter. These results demonstrated that expression of hfq was repressed by the CRP-cAMP complex. The presence of glucose resulted in increased Hfq protein levels, which decreased ompA mRNA stability. An additional experiment showed that cAMP also increased the stability of fur mRNA. Taken together, these results suggested that the repression of Hfq by cAMP may contribute to the stability of other mRNA in E. coli.
Further investigation of vibration induced by harmonic loadings applied at circular rigid plate on half-space medium
(2011-10-01)
Liou, Gin-Show
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土木工程學系
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Department of Civil Engineering
This article is the further investigation of vibration induced by harmonic loadings applied at a circular rigid plate on a half-space medium as reported by Liou (Liou, G.S., 2009. Vibrations induced by harmonic loadings applied at circular rigid plate on half-space medium. Journal of Sound and Vibration, 323, 257-269). The main purposes of this article are (1) to give the semi-analytic solution for vibration at any specific location in half-space medium; (2) to calculate the total average energy flux over one period of vibration time from the surfaces of a cylindrical cavity. The reason to evaluate the total average energy flux is that the fluctuation phenomenon of vibration amplitude along the distance from the vibration source (circular rigid plate) has been observed by Liou (2009) and can be seen from the numerical results in this article. To calculate the total average energy flux from the surfaces, piecewise linear distribution of energy flux intensity along z-direction for cylindrical surface and r-direction for bottom surface of the cylindrical cavity is assumed. The results show that the total average energy flux from the surfaces attenuates as distance from vibration source increases. This is due to the material damping in the half-space medium. The attenuation of total average energy flux is faster as the damping in the half-space medium is higher.