Browsing by Issue Date, starting with "2004-09-01"

Now showing 1 - 20 of 69621

Interacting electrons and holes in quasi-2D quantum dots in strong magnetic fields
(2004-09-01)
Hawrylak, P
;
Sheng, W
;
Cheng, S
;
電子物理學系
;
Department of Electrophysics
Theory of optical properties of interacting electrons and holes in quasi-2D quantum dots in strong magnetic fields is discussed. In two dimensions and the lowest Landau level, hidden symmetries control the interaction of the interacting system with light. By confining electrons and holes into quantum dots hidden symmetries can be removed and the excitation spectrum of electrons and excitons can be observed. We discuss a theory electronic and of excitonic quantum Hall droplets at a filling factor nu = 2. For an excitonic quantum Hall droplet the characteristic emission spectra are predicted to be related to the total spin of electron and hole configurations. For the electronic droplet the excitation spectrum of the droplet can be mapped out by measuring the emission for increasing number of electrons.
Equivalence classes of Vogan diagrams
(2004-09-01)
Chuah, MK
;
Hu, CC
;
應用數學系
;
Department of Applied Mathematics
A Vogan diagram is a Dynkin diagram with an involution, and the vertices fixed by the involution may be painted. They represent real simple Lie algebras, and two diagrams are said to be equivalent if they represent the same Lie algebra. In this article we classify the equivalence classes of all Vogan diagrams. In doing so, we find that the underlying Dynkin diagrams have certain properties in graph painting. We show that this combinatorial property provides an easy classification for most of the simply-laced Dynkin diagrams. (C) 2004 Published by Elsevier Inc.
A simple approach using Bouwer and Rice's method for slug test data analysis
(2004-09-01)
Yang, SY
;
Yeh, HD
;
環境工程研究所
;
Institute of Environmental Engineering
Slug test data obtained from tests performed in an unconfined aquifer are commonly analyzed by graphical or numerical approaches to determine the aquifer parameters. This paper derives three fourth-degree polynomials to represent the relationship between Bouwer and Rice's coefficients and the ratio of the screen length to the radius of the gravel envelope. A numerical approach using the nonlinear least squares and Newton's method is used to determine hydraulic conductivity from the best fit of the slug test data. The method of nonlinear least squares minimizes the sum of the squares of the differences between the predicted and observed water levels inside the well. With the polynomials, the hydraulic conductivity can be obtained by simply solving the nonlinear least squares equation by Newton's method. A computer code, SLUGBR, was developed from the derived polynomials using the proposed numerical approach. The results of analyzing two slug test datasets show that SLUGBR can determine hydraulic conductivity with very good accuracy.
己未年暮春過新公園楓林即事
(2004-09-01)
管管
己未年暮春過新公園楓林即事
(2004-09-01)
管管
Intelligent call admission control for wideband CDMA cellular systems
(2004-09-01)
Shen, S
;
Chang, CJ
;
Huang, CY
;
Bi, Q
;
電子工程學系及電子研究所
In this paper, we propose intelligent call admission control for wideband code-division multiple-access (CDMA) cellular systems to support differentiated quality-of-service (QoS) requirements, guarantee the forced termination probability of handoffs, and maximize the spectrum utilization. The intelligent call admission controller (ICAC) contains a fuzzy call admission processor to make admission decision for a call request by considering QoS measures such as the forced termination (drop call) probability of handoff, the outage probability of all service types, the predicted next-step existing-call interference, the link gain, and the estimated equivalent interference of the call request. The pipeline recurrent neural network (PRNN) is used to accurately predict the next-step existing-call interference, and the fuzzy logic theory is applied to estimate the new/handoff call interference based on knowledge of effective bandwidth method. Simulation results indicate that ICAC achieves system capacity higher than conventional CAC schemes by an amount of more than 10% in both low and high moving speed cases. Moreover, ICAC can cope with the unpredictable statistical fluctuation of wireless multimedia traffic; it always fulfill QoS requirements for all service types and keep the forced termination probability satisfied, while the CAC of multimedia calls (MCAC) and SIR-based CAC with intercell interference prediction (PSIR-CAC) fail to adapt to the variation of traffic conditions.
Time-resolved photoluminescence and capacitance-voltage analysis of the neutral vacancy defect in silicon implanted SiO2 on silicon substrate
(2004-09-01)
Lin, GR
;
Lin, CJ
;
Yu, KC
;
光電工程學系
;
Department of Photonics
The nanosecond photoluminescence (PL) dynamics of neutral oxygen vacancy (NOV) defects at 410-460 nm, and less pronounced nanocrystallite Si precursor (E'(delta)) defects at 520 nm in multi-energy silicon-ion-implanted SiO2 (SiO2:Si+) are investigated. The density of NOV defects in as-implanted SiO2:Si+ of 8x10(16) cm(-3) (or 2.5x10(16) cm(-3) calculated from time-resolved PL) is determined by using capacitance-voltage measurement. After annealing at 1100 degreesC for 3 h, the NOV defects are completely activated with a concentration of 4.8x10(17) cm(-3) and a corresponding absorption cross section of 9x10(-17) cm(2). The time-resolved PL lifetime of NOV defects in SiO2:Si+ is significantly shortened from 26 to 3.6 ns and these defects are fully activated after annealing for 3 h. Longer annealing time greatly attenuates the blue-green PL intensity and eliminates the NOV defects, whereas the PL intensity and concentration of E'(delta) defects with lifetime of 20-50 ns increases by a factor of 2. (C) 2004 American Institute of Physics.
Chaos, chaos control and synchronization of the vibrometer system
(2004-09-01)
Ge, ZM
;
Lin, CC
;
Chen, YS
;
機械工程學系
;
Department of Mechanical Engineering
The dynamic system of the vibrometer is shown to produce regular and chaotic behaviour as the parameters are varied. When the system is non-autonomous, the periodic and chaotic motions are obtained by numerical methods. Many effective methods have been used in chaos synchronization. It has been shown that chaos can be synchronized using special feedback control and that external excitations affect the synchronization.
Formulation of a family of sure-success quantum search algorithms
(2004-09-01)
Hsieh, JY
;
Li, CM
;
Lin, JS
;
Chuu, DS
;
電子物理學系
In this work, we consider a family of sure-success quantum algorithms, which is grouped into even and odd members for solving a generalized Grover search problem. We prove the matching conditions for both groups and give the corresponding formulae for evaluating the iterations or oracle calls required in the search computation. We also present how to adjust the phase angles in the generalized Grover operator to ensure the sure-success if minimal oracle calls axe demanded in the search.
Designing an XML-based context-aware transformation framework for mobile execution environments using CC/PP and XSLT
(2004-09-01)
Kao, TH
;
Yuan, SM
;
資訊工程學系
;
Department of Computer Science
Mobile and embedded devices provide the function of surfing the Internet anytime and anywhere. There are several kinds of mobile execution environments (MExE) built on these appliances, such as WAP, J2ME, PJava, and Microsoft CLI. It is difficult for programmers to write a program only once and then execute it on these mobile devices. The primary reason is there are a variety of devices with different runtime environments and diverse hardware/software capabilities. Therefore, in order to accomplish the following: (1) applications can be designed regardless of what kind of the target mobile device belongs to; (2) the program of an application can be automatically adapted to the target MExE environments. We propose an XML-based Context-Aware transformation Framework (X-CAF). In this framework, we design an XML-based programming model to divide programmers into two roles, user interface (UI) designer and logic programmer, so as to efficiently develop an application in separation-of-concern way. Besides, we exploit the XSLT/XPath transformation mechanism to transform documents of XML User-interface Language (XUL) and LoGic Markup Language (LGML) into others of the target MExE languages by means of the context information, device capabilities and user preferences. Moreover, to generate codes of the applications flexibly and efficiently, we divide the code processing of an application into that of the user interface occurring at runtime and that of the event-handling logic occurring at static time. In brief, our paper contributes an XML-based application development environment and transformation framework to the access to device independence. (C) 2003 Elsevier B.V. All rights reserved.
Chaos synchronization and parameter identification for loudspeaker systems
(2004-09-01)
Ge, ZM
;
Leu, WY
;
機械工程學系
;
Department of Mechanical Engineering
The identical two-degrees-of-freedom loudspeaker systems are discussed for synchronization of chaos in this paper. Two methods are used to synchronize two identical chaotic systems with different initial condition: the adaptive control and the Gerschgorin's theorem. Finally we research the parameter identification for two identical two-degrees-of-freedom loudspeaker systems by adaptive control and random optimization method. (C) 2004 Elsevier Ltd. All rights reserved.
Evaluation of dynamic vehicle load on bridge decks
(2004-09-01)
Lin, JH
;
Weng, CC
;
土木工程學系
;
Department of Civil Engineering
Developed herein is a spectral approach for evaluating the dynamic vehicle load due to the passage of a vehicle moving at constant speed along a rough bridge surface. Based on the approach, a simple closed-form solution for predicting the variation of dynamic vehicle load on a bridge deck is derived. Numerical examples of the application of the solution to a simply-supported bridge are presented. Four different classes of pavement roughness (including: very good, good, average, and poor pavements) and three different vehicle speeds (speeds of 60, 100, and 140 km/h) are used in numerical analysis. The Dynamic Load Coefficient (DLC), a parameter used to characterize the magnitude of dynamic vehicle load, is estimated. The effects of vehicle speed and pavement roughness on the variation of dynamic vehicle load are investigated. It is concluded that if the effect of engine motion on vehicle vibration is disregarded, both the DLC and standard deviation of dynamic vehicle load are proportional to the square root of the pavement roughness coefficient S(no) for a specified vehicle speed.
The life cycle of the policy for preventing road accidents: an empirical example of the policy for reducing drunk driving crashes in Taipei
(2004-09-01)
Chang, HL
;
Yeh, CC
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
The purpose of this paper is to examine the temporal variation of the effect of preventive policy on reducing traffic accidents. The life cycle theory was introduced to describe the safety effect of the intervening policy over time. Poisson regression models with dummy-based and time-based specifications were used to evaluate the effect of an intervening policy over an observation period following its implementation. The policy of "Criminal sanction for drunk driving (CSFDD)" in Taipei city was evaluated as an empirical example to determine whether the temporal variation of safety effect happened to the CSFDD policy. The study results showed that alcohol consumption, arresting the drunk driving offenders, and the implementation of the CSFDD were the significant factors affecting the rate of occurrence of fatal accidents involving drunk driving. The effect of the CSFDD policy appeared to be a rapid initial response followed by a lowerrate of decay. The existence of the life cycle implies that employing different observation periods following the implementation of a specific policy to evaluate its performance may obtain different effects. The results of this study are crucial for policy evaluation. The effects of safety policy should be carefully interpreted in order to avoid misleading the relevant authorities in coming to the wrong conclusions and as such make the wrong decisions. 9 (C) 2003 Elsevier Ltd. All rights reserved.
A TaN-HfO2-Ge pMOSFET with novel SiH4 surface passivation
(2004-09-01)
Wu, N
;
Zhang, QC
;
Zhu, CX
;
Chan, DSH
;
Du, AY
In this letter, we demonstrate a novel surface passivation process for HfO2 Ge pMOSFETs using SiH4 surface annealing prior to HfO2 deposition. By using SiH4 passivation, a uniform amorphous interfacial layer is formed after device fabrication. Electrical results show that the HfO2 Ge MOSFET with Si-passivation exhibits less frequency dispersion, narrower gate leakage current distribution, and a similar to 140% higher peak mobility than that of the device with surface nitridation.
Enhanced microstrip filter design with a uniform dielectric overlay for suppressing the second harmonic response
(2004-09-01)
Kuo, JT
;
Jiang, MS
;
電信工程研究所
;
Institute of Communications Engineering
Parallel-coupled microstrip filters are designed to suppress spurious response at twice the passband frequency (2f(o)) with a uniform dielectric overlay. The overlay dielectric is used to equalize the modal phase velocities of each coupled stage. Based on the method, we have a large degree of freedom in choosing thickness and permittivity or the overlay dielectric. The image impedances of all the coupled stages in such a filter need adjusting to complete the filter synthesis. Two filters are fabricated and measured results show a good agreement with the simulation. A suppression of at least 40 dB to the spurious responses at 2f(o) is achieved.
Vertex and tree arboricities of graphs
(2004-09-01)
Chang, GJ
;
Chen, CY
;
Chen, YP
;
應用數學系
;
Department of Applied Mathematics
This paper studies the following variations of arboricity of graphs. The vertex ( respectively, tree) arboricity of a graph G is the minimum number va( G) ( respectively, ta( G)) of subsets into which the vertices of G can be partitioned so that each subset induces a forest ( respectively, tree). This paper studies the vertex and the tree arboricities on various classes of graphs for exact values, algorithms, bounds, hamiltonicity and NP-completeness. The graphs investigated in this paper include block-cactus graphs, series-parallel graphs, cographs and planar graphs.
R&D in China: an empirical study of Taiwanese IT companies
(2004-09-01)
Lu, LYY
;
Liu, JS
;
經營管理研究所
;
Institute of Business and Management
This study extends the research on R&D (research and development) internationalization to a new environmental context (two Asian newly-industrialized economies, mainland China and Taiwan). Based on a survey of 56 major Taiwanese information technology (IT) companies, the status of R&D internationalization with Taiwan as the home and mainland China as the host is investigated. Human-capital-augmentation is found to be the key motive for Taiwanese IT companies to extend R&D activities to the mainland. Accessing capable yet cost effective local engineers with an additional benefit of geographical and linguistic proximity is the major context of this motive. The location decision is based on three considerations - access to engineers, proximity to manufacturing site, and competition avoidance. Finally, three operational patterns of conducting the international design and development (D&D) activities are categorized, which are 'home-base-integration', 'host-base-integration', and 'product life cycle'.
Direct COSi2 thin-film formation with homogeneous nanograin-size distribution by oxide-mediated silicidation
(2004-09-01)
Chang, JJ
;
Liu, CP
;
Chen, SW
;
Chang, CC
;
Hsieh, TE
By annealing at 460 degreesC for 120 s followed by 600 degreesC 120 s, nanocrystalline CoSi2 thin film with an average grain size of 5 nm can be directly formed from a Co/SiOx/Si multilayer with the SiOx, as a mediated layer. It is found that annealing at 460 degreesC for enough time is crucial for generating enough diffusion channels within the SiOx, layer. After these channels are created, subsequent annealing at 600 degreesC keeps these channels open and is responsible for rapid grain growth. In other words, by using two-step annealing, nucleation and growth processes can be effectively controlled and, hence, the resulting microstructure. The homogeneous nanograin-size distribution is important for ultralarge-scale integration technology below 90 nm to prevent resistance degradation induced by CoSi2, agglomeration. (C) 2004 American Vacuum Society.
製作複晶矽薄膜電晶體之方法
(2004-09-01)
葉清發
;
陳添富
【發明摘要】本發明係一種製作複晶矽薄膜電晶體之方法，係可改善複晶矽薄膜電晶體的電特性與可靠度，在傳統四道光罩製作薄膜電晶體之前，先做選擇性氧化矽薄膜，此技術除了可利用雷射側向再結晶來提高複晶矽薄膜電晶體的場效載子移動率之外，具厚源極(Thick Source)/汲極(Thick Drain)且薄通道(Thin Channel)結構更可降低靠近汲極(Drain)端的側向電場及通道的缺陷密度，因而可改善薄膜電晶體的可靠度。
A novel 3D planar object reconstruction from multiple uncalibrated images using the plane-induced homographies
(2004-09-01)
Chou, HL
;
Chen, Z
;
資訊工程學系
;
Department of Computer Science
A computer vision method is proposed to determine all the visible 3D planar surfaces in a scene from uncalibrated images and locate them in a single 3D projective space. Most of the existing methods for reconstructing planar objects use point correspondences to estimate the fundamental matrix and derive the compatible projection equations, before they apply the standard triangulation technique to find the 3D points and fit the planes to the 3D points. This type of approaches is generally slow and less accurate because the 3D points are estimated separately, making them vulnerable to image error. We present a plane based reconstruction method to estimate the 3D projective structure using the planar homographies estimated from the plane features in the images. First, we estimate the homography for each visible plane.. and then we use the homographies of two primary planes to compute an epipole. We proceed to represent the epipolar geometry for each image pair using the estimated homography and epipole, together with a specified reference plane coefficient vector. Next, we show that the 3D plane coefficient vector of any plane visible in each image pair can be determined with respect to the reference plane coefficient vector once its planar homography is found. Finally, the reconstruction results obtained in individual projective spaces are integrated within a common projective space. To this end. we use the homography and plane equation information of two planes and the epipole associated to derive the coordinate transformation matrix between two involved projective spaces. To evaluate the performance of our method, we apply our method to the synthetic images and real images. All the results indicate the method works successfully. (C) 2004 Published by Elsevier B.V.