Browsing by Issue Date, starting with "2005-12-25"

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A numerical study on the evolution and structure of a stress-driven free-surface turbulent shear flow
(2005-12-25)
Tsai, WT
;
Chen, SM
;
Moeng, CH
;
土木工程學系
;
Department of Civil Engineering
Turbulent shear flow beneath a flat free surface driven by a surface stress is simulated IF numerically to gain a better understanding of the hydrodynamic processes governing the scalar transfer across the air-water interface. The simulation is posed to mimic the subsequent development of a wind-driven shear layer as in a previous experiment except that the initiation of the surface waves is inhibited, thus focusing on the boundary effect of the stress-imposed surface on the underlying turbulent flow and vice versa. Despite the idealizations inherent in conducting the simulation, the computed flow exhibits the major surface features, qualitatively similar to those that appear in the laboratory and field experiments. Two distinct surface signatures, namely elongated high-speed streaks and localized low-speed spots, are observed in the simulated flow. Including temperature as a passive tracer and describing an upward heat flux at the surface, we obtain high-speed streaks that are colder and low-speed spots that are warmer than the surrounding regions. The high-speed streaks, arranged with somewhat equal cross-spacing of centimetres scale, are formed by an array of streamwise jets within the viscous sublayer immediately next to the surface. Beneath the streaks, counter-rotating streamwise vortex pairs are observed among other prevailing elongated vortices. However, they are significantly shorter in length and more irregular than their corresponding high-speed streaks at the surface. Accompanying the more organized high-speed streaks, localized regions of low streamwise velocity emerge randomly on the surface. These low-speed spots are attributed to strong upwelling flows which disrupt the viscous sublayer and also bring up the submerged fluids of low streamwise velocity. The occasional interruptions of the streamwise high-speed Jets by the upwelling flows account for bifurcation or dislocation of the surface streaks. Statistics of the turbulence are presented and their implications for the formation of the flow structures are discussed.
Ab initio characterization of electron transfer coupling in photoinduced systems: Generalized Mulliken-Hush with configuration-interaction singles
(2005-12-29)
Chen, HC
;
Hsu, CP
;
應用化學系分子科學碩博班
;
Institute of Molecular science
To calculate electronic couplings for photoinduced electron transfer (ET) reactions, we propose and test the use of ab initio quantum chemistry calculation for excited states with the generalized Mulliken-Hush (GMH) method. Configuration-interaction singles (CIS) is proposed to model the locally excited (LE) and charge-transfer (CT) states. When the CT state couples with other high lying LE states, affecting coupling values, the image charge approximation (ICA), as a simple solvent model, can lower the energy of the CT state and decouple the undesired high-lying local excitations. We found that coupling strength is weakly dependent on many details of the solvent model, indicating the validity of the Condon approximation. Therefore, a trustworthy value can be obtained via this CIS-GMH scheme, with ICA used as a tool to improve and monitor the quality of the results. Systems we tested included a series of rigid, sigma-linked donor-bridge-acceptor compounds where "through-bond" coupling has been previously investigated, and a pair of molecules where "through-space" coupling was experimentally demonstrated. The calculated results agree well with experimentally inferred values in the coupling magnitudes (for both systems studied) and in the exponential distance dependence (for the through-bond series). Our results indicate that this new scheme can properly account for ET coupling arising from both through-bond and through-space mechanisms.
Fast fourier transform processor, dynamic scaling method and fast Fourier transform with radix-8 algorithm
(2005-12-29)
Lee, Chen-Yi
;
Lin, Yu-Wei
The present invention provides a fast Fourier transform processor, dynamic scaling method and fast Fourier transform with radix-8 algorithm. It reduces quantization errors generated from the operation by using a matrix prefetch buffer-based fast Fourier transform processor. Operation sizes of the matrix prefetch buffer as block sizes the invention adjust the signals against overflow by the status of signals in each block. It can shunt time of complex multiplication operation systematically and reduce operation complexity in butterfly units by utilizing algorithms of 3-step radix-8 fast Fourier transform and re-scheduling. Moreover, the present invention provides a fast Fourier transform processor for realizing the methods and algorithms mentioned above.
Multi-slope handoff algorithm for controlling dynamic communication quality in wireless communications
(2005-12-29)
Huang, Ching Yao
;
Tsai, Ming Yuan
;
Huang, Joe
A multi-slope handoff algorithm for controlling dynamic communication quality in wireless communications is proposed to let a mobile node adjust the handoff slope according to different communication connection situations for setting the optimum add/drop connection trigger thresholds. The algorithm comprises the following steps. First, a mobile node receives pilot strengths of its service pilot and nearby pilots to produce an aggregate strength. Next, the mobile node determines whether to perform handoff according to the magnitude of the aggregate strength. The handoff action is then controlled by multi-slope handoff operations to set an appropriate slope and to calculate the add/drop connection trigger thresholds when performing handoff. Finally, the pilot to be connected is selected based on the communication quality at that time. In this way, the quality of the communication service can be enhanced, the connection power consumption can be lowered, and the communication channel usage can be reduced.
A method for calibrating a motorized object rig
(2006)
Huang, PH
;
Tsai, YP
;
Lo, WY
;
Shih, SW
;
Chen, CS
Object Movies (OMs) have been successfully used in many applications. However, the techniques for acquiring OMs still need to be improved if high-quality and efficient OMs are desired. In this paper, we present a method for calibrating a motorized object rig to facilitate the acquisition of OMs. We first apply the CPC kinematic model to formulate the 3D configuration of the device, and then propose a method to estimate the parameters of the CPC model of the device. Furthermore, a visual tool is provided for users to adjust the controllable axes of the rig according to the estimated results. After this calibration, more accurate camera parameters can be obtained and then be used for different purposes. In this work, we use the parameters to reconstruct, from an OM, the 3D model of the object, and then adjust the OM according to the center of the 3D model so that a high-quality OM can be obtained for rendering.
科學概念的建構與重建數位學習研究---總計畫(III)
(2006)
佘曉清
;
SHE HSIAO-CHING
;
國立交通大學教育研究所
漁港水域之生態模式基礎研究
(2006)
郭一羽
;
KUO YI-YU
;
交通大學土木工程系
漁港水域之水質改善，對改善漁港的景觀生態環境而言是最重要的課題。水質與水中的浮游生物息息相關，而因一般的水質改善目標或評估標準難以確立，故利用生物來判斷水質是合理的作法。本研究擬利用現地水質與浮游生物的調查資料與數值計算模式，探討水質與浮游生物的相關性。研究目標擬建立港內水質數值模式、浮游生物之棲地模式，以及以浮游生物為主之生物指標或指標生物。研究成果期望對營造具生態性之親水環境的港池水域有所助益。
自身排列高分子薄膜太陽能電池之開發(II)
(2006)
陳方中
;
Chen Fang-Chung
;
交通大學光電工程研究所
口語、文字、祖先故事：貴州東部苗人的古歌與家譜比較研究
(2006)
簡美玲
;
Mei-Ling Chien
;
國立交通大學人文社會學系
本二年期研究計劃在面對口語及文字並存的當代貴州苗人社群，及其所創造的兩套歷史論述之間的對照及分離。本研究假設兩套對祖先及系譜想像有所區別的歷史論述，不僅再現苗社群對人觀、空間、時間(歷史)及中國國家的兩種不同想像，並也突顯口語及文字相互對照、分離的張力，以及由此而生的兩套在地的文明化經驗。研究對像為貴州東部清水江畔的苗人社群，及其以口語及文字而敘述祖先形象及祖先遷移、墾拓經歷的兩種文類：一為漢字書寫、印刷出版的家譜，一為由地方歌師傳唱及記音的苗族大歌(或古歌)。就區域研究及理論議題而言，這個比較研究仍在面對原本無文字的西南邊陲社會，對中國國家長期文字化及文明化(儒家)的在地回應。為探討文字化在西南中國苗人社區所展現的在地性，以及口語、文字的對照及分離，與苗人對祖先及國家的想像，本研究主旨有二：(1)通過文本的比較分析，討論口語及文字之祖先故事的結構差異，以及對時、空、人、國家的差異想像。(2) 比較及討論村寨苗人的性別、年齡、教育，與對兩套祖先故事之主觀觀點的對比及差異。本計畫第一年在釐清口語系統下苗族古歌的敘述結構，以及苗人藉由哪些詩歌語言的元素、意象的組合，傳達對祖先及遷徙時、空的想像。
分權式逆向供應鏈價格流量合約設計之研究
(2006)
洪一薰
;
Hong I-Hsuan Ethan
;
國立交通大學工業工程與管理學系(所)
分權式逆向供應鏈（Decentralized reverse supply chains），是由一群獨立運作的個體所組成，個體在系統中代表不同的功能，如回收商（Collectors）、集中商（Consolidation sites）或處理商（Processors），而個體中通常也互相競爭。多數逆向供應鏈之文獻以中央集權式（Centralized）的基本架構來規劃相關決策，在Centralized 系統中，系統規劃者知悉個體的資訊並訂定個體之決策變數使得系統表現最佳化。然而，逆向供應鏈系統經常是由一群各自獨立運作的個體所組成，每個獨立的個體在決策時有各自的考量，個體的決策變數（流量及收購價格）會影響到其它個體的表現，其它個體的決策也會影響到各自的表現，且個體也不願意將自己的資訊提供給其它個體或向大眾揭露。此種型態之系統，稱之為分權式（Decentralized）系統。本研究擬考慮一多階分權式逆向供應鏈系統，假設該系統由上游邊界層、中間階層及下游邊界層所組成。每個階層由一群獨立運作的個體所組成，上游個體經由制定價格 -流量合約關係與其下游個體所溝通，而下游個體訂定物料之收購價格，本研究擬以穩健性最佳化（Robust optimization）及貝氏決策分析（Bayesian decision-making）訂定此一合約關係，藉以描述下游個體收購價格之不確定性。
45-nm CMOS 80~120GHz 射頻前端電路前瞻研究與設計
(2006)
吳重雨
;
CHUNG-YUWU
;
交通大學電子工程系
中小學資訊素養之概念診斷、課程設計與評量研究(II)
(2006)
周倩
;
CHOU CHIEN
;
國立交通大學教育研究所
A 52mW 1200MIPS compact DSP for multi-core media SoC
(2006)
Ou, Shih-Hao
;
Lin, Tay-Jyi
;
Huang, Chao-Wei
;
Kuo, Yu-Ting
;
Chao, Chie-Min
This paper presents a DSP core for multi-core media SoC, which is optimized to execute a set of signal processing tasks very efficiently. The fully-programmable core has a data-centric instruction set and a corresponding latency-insensitive microarchitecture, where the hardware design is optimized concurrently with its automatic software generator. The proposed DSP core has 3X performance (in cycles) of those found in commercial dual-core application processors with similar computing resources. The silicon implementation in UMC 0.18 mu m 1P6M CMOS technology operates at 314MHz and consumes only 52mW average power.
An analysis of channel utilization for the IEEE 802.11 with aggregation
(2006)
Sung, Cheng-Chia
;
Kuo, Yaw-Wen
;
Lee, Tsern-Huei
;
電信工程研究所
;
Institute of Communications Engineering
The IEEE 802.11 MAC provides a method for multiple users to share the wireless media. The channel utilization is limited because of protocol overhead no matter how fast the payload is transmitted. To increase utilization, frame aggregation is a straightforward way to improve the channel efficiency. This paper presents an analytic method to estimate the utilization for RTS/CTS-based contention access mechanism with unidirectional or bidirectional aggregation. Simulation results are also provided to show the accuracy of the analytic model.
極低溫下電子相位相干時間之量測(II)
(2006)
林志忠
;
LIN JUHN-JONG
;
交通大學物理研究所
MultiSensor processing for signal extraction and applications
(2006)
Chi, Chong-Yung
;
Lee, Ta-Sung
;
Luo, Zhi-Quan
;
Wang, Yue
;
Yao, Kung
基地邊緣 : 基地後傳之1
(奇幻基地出版, 2006)
艾西葛夫
;
Asimov, Isaac
Living in refuge: Kashmiri Pundit women
(Routledge, 2006)
K. Arora
Optimal design theories and applications of tuned mass dampers
(2006-01-01)
Lee, CL
;
Chen, YT
;
Chung, LL
;
Wang, YP
;
土木工程學系
An optimal design theory for structures implemented with tuned mass dampers (TMDs) is proposed in this paper. Full states of the dynamic system of multiple-degree-of-freedom (MDOF) structures, multiple TMDs (MTMDs) installed at different stories of the building, and the power spectral density (PSD) function of environmental disturbances are taken into account. This proposed method allows for a more extensive application and successfully releases the limitations based on simplified models. The optimal design parameters of TMDs in terms of the damping coefficients and spring constants corresponding to each TMD are determined through minimizing a performance index of structural responses defined in the frequency domain. Moreover, a numerical method is also proposed for searching for the optimal design parameters of MTMDs in a systematic fashion such that the numerical solutions converge monotonically and effectively toward the exact solutions as the number of iterations increases. The feasibility of the proposed optimal design theory is verified by using a SDOF structure with a single TMD (STMD), a five-DOF structure with two TMDs, and a ten-DOF structure with a STMD. (c) 2005 Elsevier Ltd. All rights reserved.
21世紀現代教育之我見
(交大出版社, 2006)
吳重雨