Browsing by Issue Date, starting with "2004-03-28"

Now showing 1 - 20 of 70467

Self-generated NAF nano template assisted formation of porous carbon nanotube arrays.
(2004-03-28)
Chiu, HT
;
Huang, CH
;
Chang, YH
;
Lee, CY
;
Cheng, SF
Updated numerical performance and throughput benchmark for electronic structure calculations in PC-LINUX systems.
(2004-03-28)
Yu, JSK
;
Hwang, JK
;
Tang, CY
;
Yu, CH
;
生物科技學系
黃永松埋首案前堆疊出漢聲歷史
(2004-03-29)
陳冠茜
Star polymers via atom transfer radical polymerization from adamantane-based cores
(2004-03-29)
Huang, CF
;
Lee, HF
;
Kuo, SW
;
Xu, HY
;
Chang, FC
A series of novel multifunctional initiators derived from adamantane-based derivatives have been used in the syntheses of various styrenic and (meth)acrylic star polymers by atom transfer radical polymerization (ATRP). Conditions were identified in each system to produce star polymers with nearly monomodal molecular distributions. These synthesized star polymers have glass transition temperatures similar to those known for high-molecular-weight linear polymers. We obtained a series of adamantane-contained star polymers covering a wide range of molecular weights by adjusting the monomer-to-initiator ratio and the solvent polarity. Because of reaction heterogeneity and inevitable termination processes, the occurrence of star-star coupling led to a lower than predicted molecular weight polydispersity. When hydrolyzed from their cores by NaOH, the values of Mw of the arms of the PMMA star polymer did not change with reaction time, at least for the first 48 h of the reaction, which implies that no significant PMMA hydrolysis occurs within this interval of time. (C) 2004 Elsevier Ltd. All rights reserved.
Rotationally selected product pair correlation in F+CD4 -> DF(nu('))+CD3(nu=0,N)
(2004-04-01)
Zhou, JG
;
Shiu, WC
;
Lin, JJ
;
Liu, KP
;
應用化學系
The title reaction was studied in a crossed-beam experiment by imaging of state-selected products. The rotational state selection of the CD3 products was achieved using (2+1) resonance-enhanced multiphoton ionization. The coincident information on the DF coproducts was revealed in a state-resolved manner from time-sliced velocity map images. Significant dependences of both the correlated differential cross sections and the DF vibrational branching ratios on the "tagged" CD3 rotation states were found. The dynamical implications of one of the major findings are discussed. (C) 2004 American Institute of Physics.
Characterization of hydrogen-treated pentacene organic thin film transistors
(2004-04-01)
Yang, JY
;
Suen, SC
;
Whang, WT
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The electrical characteristics of hydrogen-postannealed and hydrogen-plasma-treated pentacene thin film transistors (TFTs) have been investigated. Experimental results have shown that the hydrogen-treated TFTs have improved field-effect mobility and a higher current on/off ratio, compared to untreated devices. The on/off current ratio of the hydrogen-treated devices was markedly increased. However, the TFTs treated with hydrogen plasma have degraded field-effect mobility, compared to hydrogen-postannealed devices.
Field emission properties of aligned carbon nanotubes grown on stainless steel using CH4/CO2 reactant gas
(2004-04-01)
Lin, CL
;
Chen, CF
;
Shi, SC
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Aligned carbon nanotubes (CNTs) were grown on stainless steel 304 by bias-enhanced microwave plasma chemical vapor deposition, using CH4/CO2 as the reactant gas. A bias was applied to the microwave plasma to grow the nanotubes over various periods. Experimental results show that well-aligned CNTs grow on stainless steel at a negative bias of - 300 V Energy dispersive spectrometer on TEM indicated that the metal catalyst on the top of the CNTs includes Fe and Ni, but not Cr. The field emission properties of the resultant CNTs were obtained at a negative bias of - 300 V: the emission current was 194 muA at 2.2 V/mum; and the turn-on voltage, which is the voltage needed to extract current density of 10 muA /cm(2), was 1.4 V/mum. (C) 2003 Elsevier B.V. All rights reserved.
空原上之小樹呀
(2004-04-01)
管管
Field emission and photofluorescent characteristics of zinc oxide nanowires synthesized by a metal catalyzed vapor-liquid-solid process
(2004-04-01)
Li, SY
;
Lin, P
;
Lee, CY
;
Tseng, TY
;
材料科學與工程學系
The ZnO nanowires synthesized by vapor-liquid-solid growth mechanism with Cu and Au as the catalyst were investigated. The principal differences in morphology between Cu and Au catalyzed ZnO nanowires are observed and lead to significant differences in their field emission and photofluorescent characteristics. The Cu catalyzed ZnO nanowires with a high-quality wurtzite structure were grown vertically on p-type Si(100) substrate along [0002] direction. A strong ultraviolet emission at 381 nm is observed. These ZnO nanowires show excellent field emission properties with turn-on field of 0.83 V/mum and corresponding current density of 25 muA/cm(2). The emitted current density of the ZnO nanowires is 1.52 mA/cm(2) at a bias field of 8.5 V/mum. The large field emission area factor, beta arising from the morphology of the nanowire field emitter, is partly responsible for the good emission characteristics. The ZnO nanowires with high emission current density and low turn-on field are expected to be used in field emission flat panel display. (C) 2004 American Institute of Physics.
Advanced obfuscation techniques for Java bytecode
(2004-04-01)
Chan, JT
;
Yang, W
;
資訊工程學系
;
Department of Computer Science
There exist several obfuscation tools for preventing Java bytecode from being decompiled. Most of these tools simply scramble the names of the identifiers stored in a bytecode by substituting the identifiers with meaningless names. However, the scrambling technique cannot deter a determined cracker very long. We propose several advanced obfuscation techniques that make Java bytecode impossible to recompile or make the decompiled program difficult to understand and to recompile. The crux of our approach is to over use an identifier. That is, an identifier can denote several entities, such as types, fields, and methods, simultaneously. An additional benefit is that the size of the bytecode is reduced because fewer and shorter identifier names are used. Furthermore, we also propose several techniques to intentionally introduce syntactic and semantic errors into the decompiled program while preserving the original behaviors of the bytecode. Thus, the decompiled program would have to be debugged manually. Although our basic approach is to scramble the identifiers in Java bytecode, the scrambled bytecode produced with our techniques is much harder to crack than that produced with other identifier scrambling techniques. Furthermore, the run-time efficiency of the obfuscated bytecode is also improved because the size of the bytecode becomes smaller after obfuscation. (C) 2002 Elsevier Inc. All rights reserved.
An empirical analysis of the relationship between the hedge ratio and hedging horizon: A simultaneous estimation of the short- and long-run hedge ratios
(2004-04-01)
Chen, SS
;
Lee, CF
;
Shrestha, K
;
資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
This article analyzes the effects of the length of hedging horizon on the optimal hedge ratio and hedging effectiveness using 9 different hedging horizons and 25 different commodities. We discuss the concept of short- and long-run hedge ratios and propose a technique to simultaneously estimate them. The empirical results indicate that the short-run hedge ratios are significantly less than 1 and increase with the length of hedging horizon. We also find that hedging effectiveness increases with the length of hedging horizon. However, the long-run hedge ratio is found to be close to the naive hedge ratio of unity. This implies that, if the hedging horizon is long, then the naive hedge ratio is close to the optimum hedge ratio. (C) 2004 Wiley Periodicals, Inc.
Supervised motion segmentation by spatial-frequential analysis and dynamic sliced inverse regression
(2004-04-01)
Wu, HM
;
Lu, HHS
;
統計學研究所
;
Institute of Statistics
lit this paper, we propose a new method for supervised motion segmentation based on spatial-frequential analysis and dimension reduction techniques. A sequence of images could contain non-ridge motion in the region of interest and the segmentation of these moving objects with deformation is challenging. The aim is to extract feature vectors that capture the spatial-frequential information in the training set and then to monitor the variations of the feature vectors over time in the test set. Given successive images in the training set, we consider a dynamic model that extends the sliced inverse regression in Li (1991). It is designed to capture the intrinsic dimension of feature vectors that holds over a local time scale. These projected features are then used to classify training images and predict forthcoming images in the test set into distinct categories. Theoretic properties are addressed. Simulation studies and clinical studies of a sequence of magnetic resonance images are reported, which confirm the practical feasibility of this new approach.
Electromigration in sputtered copper film on plasma-treated hydrogen silsesquioxane dielectric
(2004-04-01)
Chen, CT
;
Chiou, BS
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Electromigration (EM) damage is one of the major causes for the failure of interconnects. Plasma treatment, such as dry etching, is frequently employed in the fabrication of multilevel interconnection patterns. This work investigates the hydrogen silsesquioxane (HSQ) and copper integrated systems and the effect of H-2 plasma treatment on the EM of Cu. Hydrogen plasma bombardment induces a rough HSQ surface and results in a coarse morphology of the Cu film deposited on HSQ. The crystallographic texture of Cu is also affected by the plasma treatment. A decrease in the Cu I(111)/I(200) peak ratio is observed for a specimen treated with H-2 plasma. The activation energy for EM in Cu and the EM lifetime of the Cu interconnect decreases with an increased degree of plasma treatment. The activation energies obtained, ranging from 0.76 eV to 0.94 eV, suggest that the electromigration in copper proceeds via an interfacial diffusion path. Possible mechanisms for the effects of plasma treatment are explored. The rough surface and the retarded Cu (111) orientation induced by H-2 plasma bombardment are the major causes for the decrease of activation energy and EM lifetime.
A neural network-based adaptive algorithm on the single EWMA controller
(2004-04-01)
Hsu, CC
;
Su, CT
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
The single EWMA controller has been proven to have excellent performance for small disturbances in the run-to-run process. However, incorrect selection of the EWMA parameter can have the opposite effect on the controlled process output. An adaptive system is necessary to automatically adjust the controller parameters on-line in order to have better performance. In this study, a simple and efficient algorithm based on neural networks (NN) is proposed to minimise the inflation of the output variance on line. The authors have shown that the sequence of EWMA gains, generated by a NN-based adaptive approach, converges close to the optimal controller value under IMA (1, 1), step and trend disturbance models. The paper also shows that the NN-based adaptive EWMA controller has a superior performance than its predecessors.
空原上之小樹呀
(2004-04-01)
管管
Hot carrier degradations of dynamic threshold silicon on insulator p-type metal-oxide-semiconductor field effect transistors
(2004-04-01)
Chao, TS
;
Lee, YJ
;
Huang, CY
;
Lin, HC
;
Li, YM
In this study, we compared the hot carrier effects of T-gate and H-gate Silicon on Insulator p-Type Metal-Oxide-Semiconductor Field Effect Transistors (SOI pMOSFETs) operating under dynamic threshold mode (DT-mode) and normal mode at various temperatures. By operating under DT-mode, the threshold voltage shift is reduced. However, enhanced degradations in maximum transconductance and drive current are observed when operating under DT-mode at room temperature, especially for the T-gate structure. The transconductance enlargement effect for devices operating under DT-mode, together with the non-uniform potential distribution in T-gate structure, are believed to be responsible for the observed enhanced degradations. At elevated temperatures, the hot-carrier-induced degradations are alleviated for devices operating under DT-mode, to levels close to those of the normal mode, due to reduced impact ionization at higher temperature.
Asymptotic behaviors in a transiently chaotic neural network
(2004-04-01)
Chen, SS
;
Shih, CW
;
應用數學系
;
Department of Applied Mathematics
We are interested in the asymptotic behaviors of a discrete-time neural network. This network admits transiently chaotic behaviors which provide global searching ability in solving combinatorial optimization problems. As the system evolves, the variables corresponding to temperature in the annealing process decrease, and the chaotic behaviors vanish. We shall find sufficient conditions under which evolutions for the system converge to a fixed point of the system. Attracting sets and uniqueness of fixed point for the system are also addressed. Moreover, we extend the theory to the neural networks with cycle-symmetric coupling weights and other output functions. An application of this annealing process in solving travelling salesman problems is illustrated.
空原上之小樹呀
(2004-04-01)
管管
Examining the factors that influence the intentions to adopt internet shopping and cable television shopping in Taiwan
(2004-04-01)
Li, SCS
;
傳播研究所
;
Institute of Communication Studies
Using Rogers' diffusion of innovation model, this study attempts to compare the adoption of internet shopping with that of cable television shopping in Taiwan. Rogers' diffusion model has been criticized for its pro-innovation bias, and thus this study expects that the adoption of internet shopping will be consistent with the predictions of Rogers' model, while the adoption of cable television shopping will not. A telephone survey with 1227 valid interviews was used to collect data for this study. As expected, most findings regarding internet shopping follow the predictions of this model. However, the diffusion process in relation to cable television shopping digresses from the path predicted by Rogers' model. The detailed findings of the study are discussed in the article.
Polydimethylsiloxane soft template assisted synthesis of silver nanoparticles via vapor-solid reaction growth
(2004-04-01)
Hsia, CH
;
Yen, MY
;
Chiu, HT
;
Lee, CY
;
應用化學系
A new route to synthesize silver nanoparticles via vapor-solid reaction growth (VSRG) is reported. Employing AgCl to react with (Me3Si)(4)Si in a scaled tube (433-673 K) generates silver particles (diameter greater than or equal to 10 mum). Addition of polydimethylsiloxnae (PDMS) to the reaction dramatically reduces the particle size (diameter 60-1200 nm). Moreover, formation of silver nanorods and nanocubes was discovered in some reaction conditions. Adding PDMS and varying the reaction temperature were the key factors influencing the Ag particle size.