Browsing by Issue Date, starting with "2004-10-30"

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管管作品十三首
(2004-10-30)
管管
管管作品十三首
(2004-10-30)
管管
Characteristics method with cubic-spline interpolation for open channel flow computation
(2004-10-30)
Tsai, TL
;
Chiang, SW
;
Yang, JC
;
防災與水環境研究中心
;
Disaster Prevention and Water Environment Research Center
In the framework of the specified-time-interval scheme, the accuracy of the characteristic method is Greatly related to the form of the interpolation. The linear interpolation was commonly used to couple the characteristics method (LI method) in open channel flow computation. The LI method is easy to implement, but it leads to an inevitable smoothing of the solution. The characteristics method with the Hermite cubic interpolation (HP method, originally developed by Holly and Preissmann, 1977) was then proposed to largely reduce the error induced by the LI method. In this paper, the cubic-spline interpolation on the space line or on the time line is employed to integrate with characteristics method (CS method) for unsteady flow computation in open channel. Two hypothetical examples, including gradually and rapidly varied flows, are used to examine the applicability of the CS method as compared with the LI method, the HP method, and the analytical solutions. The simulated results show that the CS method is comparable to the HP method and more accurate than the LI method. Without tackling the additional equations for spatial or temporal derivatives, the CS method is easier to implement and more efficient than the HP method. Copyright (C) 2004 John Wiley Sons, Ltd.
管管作品十三首
(2004-10-30)
管管
管管作品十三首
(2004-10-30)
管管
管管作品十三首
(2004-10-30)
管管
管管作品十三首
(2004-10-30)
管管
管管作品十三首
(2004-10-30)
管管
Effects of cross-substrate interaction on biotrickling filtration for the control of VOC emissions
(2004-11-01)
Den, W
;
Huang, CP
;
Li, CH
;
環境工程研究所
;
生物科技學系
The effects of cross-substrate interaction to the performance of a gas-phase biotrickling filter for treating a mixture of volatile organic compounds (VOCs), including three structural heterologous in acetone, toluene, and trichloroethylene, were investigated. The biotrickling filter was inoculated with microbial consortium containing at least seven bacterial species utilizing either acetone or toluene, or both, as their carbon sources. In the performance study, the column operating under variable conditions typifying the waste gas emission from the microelectronics fabrication processes achieved a total hydrocarbon (THC) removal efficiency in excess of 85% and a mineralization capacity over 50% for THC mass loading as high as 36.2 g-CH4 m(-3) h(-1). The cross-substrate effects were examined by correlating the relative changes in the mass removal of each substrate with the biodegradative capability of the microbial consortium. The degradation of trichloroethylene was primarily due to co-metabolism by the toluene-oxidizing enzymes, but the results also indicated that trichloroethylene partially induced its own degradation. Concentration increases in acetone appeared to cause a diauxie effect that suppressed degradation of toluene and trichloroethylene, and shifted the microbial population toward the selective acetone-degraders. No irrecoverable toxicity or inhibitory effects were observed throughout the experiments. These results suggest that the relative VOC concentration in the waste gas mixture is a factor as important as the biodegradative function of the microbial consortium, and thus should be carefully evaluated to satisfy the treatment objectives. (C) 2004 Elsevier Ltd. All rights reserved.
A broadband and low cost monolithic BiCMOS tuner chip
(2004-11-01)
Chen, YH
;
Cheng, TY
;
Chang, CY
;
交大名義發表
;
National Chiao Tung University
This circuit is a single chip of a BiCMOS wafer used in cable TV set-top converters;, cable modems, cable TV tuners and digital TVs. It is a double conversion tuner (DCT) structure which has better performance characteristics than the single conversion tuner (SCT). This single chip comprises two LNAs, one AGC, two LO buffers, two VCOs, two resistor-type and double-balanced Gilbert cell mixers, two synthesizers and ESD protection. Its total gain is 45.70 dB, and its total noise figure is 4.3-7.9 dB. The RF varied range, which is not only 50-860 MHz but also 50-1000 MHz, can be applied in cable TV tuners and cable modems. The consuming power is 0.885 W under 3 V and the die size is 4.8 mm(2).
Some issues of designing genetic algorithms for traveling salesman problems
(2004-11-01)
Tsai, HK
;
Yang, JM
;
Tsai, YF
;
Kao, CY
;
生物科技學系
This paper demonstrates that a robust genetic algorithm for the traveling salesman problem (TSP) should preserve and add good edges efficiently, and at the same time, maintain the population diversity well. We analyzed the strengths and limitations of several well-known genetic operators for TSPs by the experiments. To evaluate these factors, we propose a new genetic algorithm integrating two genetic operators and a heterogeneous pairing selection. The former can preserve and add good edges efficiently and the later will be able to keep the population diversity. The proposed approach was evaluated on 15 well-known TSPs whose numbers of cities range from 101 to 13509. Experimental results indicated that our approach, somewhat slower, performs very robustly and is very competitive with other approaches in our best surveys. We believe that a genetic algorithm can be a stable approach for TSPs if its operators can preserve and add edges efficiently and it maintains population diversity.
Evidence for capture of holes into resonant states in boron-doped silicon
(2004-11-01)
Yen, ST
;
Tulupenko, VN
;
Cheng, ES
;
Chung, PK
;
Lee, CP
The variation of hole population in the resonant states of B-doped Si excited by sequences of short electric-field pulses has been investigated by the technique of time-resolved step-scan far-infrared spectroscopy. From the variation of the p(3/2) absorptions, we find that the hole population in the ground state decreases continuously with the sequential electric pulses, as a result of the breakdown delay and hole accumulation in long-lived excited states. The measured time-varying spectra of the p(1/2) series have been analyzed and attributed to a significant variation of the hole population in the resonant states. We have also observed a new absorption line at 676 cm(-1) which is probably caused by the electric-field induced mixing of the resonant states. (C) 2004 American Institute of Physics.
Comparisons on properties and growth mechanisms of carbon nanotubes fabricated by high-pressure and low-pressure plasma-enhanced chemical vapor deposition
(2004-11-01)
Lin, CH
;
Lee, SH
;
Hsu, CM
;
Kuo, CT
;
材料科學與工程學系
Effects of plasma pressure and the presence of nitrogen on growth of carbon nanotubes (CNTs) and their properties were studied by using microwave plasma chemical vapor deposition (MPCVD) (pressure=600-3300 Pa) and electron cyclotron resonance chemical vapor deposition (ECR-CVD) (pressure=0.3-0.6 Pa) systems. CH4/H-2 and CH4/N-2 were used as source gases, and Co as the catalyst. The structures and properties of CNTs were characterized by using field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Raman spectra, and field emission I-V measurements. The results show that. CNTs made by higher plasma pressure system have a higher growth rate (typically 1-3 mum/min), smaller tube diameter, better field emission properties, and better tube quality. The growth rate is related to the availability of carbon source. The morphology change from spaghetti-like to well-aligned CNTs is discussed in terms of directed ions. The change in field emission properties is reasoned in terms of geometric enhancement factor and screening effect for different tube morphologies. The presence of nitrogen plasma can have the following effects: increasing tube diameter, increasing straightness of CNTs, forming of bamboo-like CNTs, deterioration of field emission properties, and shifting of Raman peak toward lower-frequency side (or increasing residual tensile stress). (C) 2004 Elsevier B.V. All rigths reserved.
Highly oriented diamond growth on SixGe1-x (100) thin films
(2004-11-01)
Chang, TF
;
Chang, L
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Highly oriented (100) diamond films have been successfully grown on SixGe1-x(100) thin films by bias enhanced nucleation (BEN) in microwave plasma chemical vapor deposition (MPCVD) system. Raman spectra show the 1332 cm(-1) peak which proves the formation of diamond. Diamond nucleation density on SixGe1-x substrate estimated by scanning electron microscopy is higher than 10(9) cm(-2). The interface between diamond and SixGe1-x substrate was characterized by transmission electron microscopy (TEM). About 20 nm decrease in thickness of the SixGe1-x film. was observed after bias enhanced nucleation step. TEM shows the existence of silicon carbide and heteroepitaxial diamond grains grown on SixGe1-x substrate. Characterization from high-resolution TEM on the specimen of short time deposition reveals that a number of epitaxial diamond grains were directly nucleated on SixGe1-x with {111} interplanar spacing ratio of diamond and SixGe1-x of 2:3. The diamond nucleation is found to be preferred on the ridge position of the rough substrate surface. Diamond {100} facets were quickly developed in the early stage of growth. (C) 2004 Elsevier B.V. All rights reserved.
具數位及無跳模連續微調波長機制之多波長外腔雷射系統
(2004-11-01)
潘犀靈
;
趙如蘋
;
藍玉屏
本發明係有關於一種電控式可調多波長外腔雷射系統，其包括：一前端面鍍抗反射膜之半導體雷射、準直鏡、液晶盒、分光光柵、聚焦透鏡和液晶像素反射鏡。控制液晶像素反射鏡之驅動電壓，可選擇雷射波長輸出。同時打開幾個像素、雷射可輸出多波長。波長頻道可用電訊號切換。改變液晶盒或(及)液晶像素反射鏡之驅動電壓可微調輸出之雷射波長。其中液晶盒和液晶像素反射鏡亦可由單一液晶像素相位可調反射鏡取代。液晶像素相位可調反射鏡係由液晶像素盒及液晶像素反射鏡組成如三明治般的結構，液晶像素反射鏡和液晶像素盒各像素之驅動電壓可分別控制，改變液晶像素反射鏡或液晶像素盒各像素之驅動電壓，即可個別或連續微調液晶每一像素對應之雷射波長輸出。
Role-based authorizations for workflow systems in support of task-based separation of duty
(2004-11-01)
Liu, DR
;
Wu, MY
;
Lee, ST
;
資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
Role-based authorizations for assigning tasks of workflows to roles/users are crucial to security management in workflow management systems. The authorizations must enforce separation of duty (SoD) constraints to prevent fraud and errors. This work analyzes and defines several duty-conflict relationships among tasks, and designs authorization rules to enforce SoD constraints based on the analysis. A novel authorization model that incorporates authorization rules is then proposed to support the planning of assigning tasks to roles/users, and the run-time activation of tasks. Different from existing work, the proposed authorization model considers the AND/XOR split structures of workflows and execution dependency among tasks to enforce separation of duties in assigning tasks to roles/users. A prototype system is developed to realize the effectiveness of the proposed authorization model. (C) 2003 Elsevier Inc. All rights reserved.
A statistic approach for deriving the short message transmission delay distributions
(2004-11-01)
Hung, HN
;
Lin, YB
;
Lu, MK
;
Peng, NF
;
統計學研究所
Short Message Service (SMS) is one of the most popular mobile data services. This paper develops a web-based short message system and analyzes the short message transmission delays based on 40 000 measured data collected from commercial operation. We investigate the distributions of SMS round-trip transmission delays. These distributions are roughly approximated by truncated normal, gamma, log-normal, and Weibull distributions with various parameters, which can be utilized in theoretical analysis. Furthermore, with the nonparametric fitting approach, we use the rejection method to develop random number generators for these delays, which can be used in any simulation models that employ SMS transmission delays.
Image descreening by GA-CNN-based texture classification
(2004-11-01)
Shou, YW
;
Lin, CT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper proposes a new image-descreening technique based on texture classification using a cellular neural network (CNN) with template trained by genetic algorithm (GA), called GA-CNN. Instead of using the fixed filters for image descreening, we are equipped with a more pliable mechanism for classifications in screening patterns. Using CNN makes it possible to get an accurate texture classification result in a faster speed by its superiority of implementable hardware and the flexible choices of templates. The use of the GA here helps us to look for the most appropriate template for CNNs more adaptively and methodically. The evolved parameters in the template for CNNs can not only provide a quicker classification mechanism but also help us with a better texture classification for screening patterns. After the class of screening patterns in the querying images is determined by the trained GA-CNN-based texture classification. system, the recommendatory filters are induced to solve the screening problems. The induction of the classification in screening patterns has simplified the choice of filters and made it valueless to determine a new structured filter. Eventually, our comprehensive methodology is going to be topped off with more desirable results and the indication for the decrease in time complexity. Index Terms-Cellular neural network (CNN), genetic algorithm (GA), image descreening, texture classification.
Simulation of 1300-nm In(0.4)Ga(0.6)As(0.986)N(0.014)/GaAs(1-x)N(x) quantum-well lasers with various GaAs(1-x)N(x) strain compensated barriers
(2004-11-01)
Chang, YA
;
Kuo, HC
;
Chang, YH
;
Wang, SC
;
光電工程學系
In this article, the laser performance of the 1300-nm In(0.4)Ga(0.6)As(0.986)N(0.014)/GaAs(1 - x)N(x) quantum-well (QW) lasers with various GaAs(1 - x)N(x) strain compensated barriers (x = 0%, 0.5%, 1%, and 2%) has been numerically investigated with a laser technology integrated simulation program. The simulation results suggest that with x = 0% and 0.5% can have better optical gain properties and high characteristic temperature coefficient To values of 110 and 94 K at the temperature range of 300-370 K. As the nitrogen composition in GaAs(1 - x)N(x) barrier increases more than 1% the laser performance degrades rapidly and the To value decreases to 87 K at temperature range of 300-340 K. This can be attributed to the decrease of conduction band carrier confinement potential between In(0.4)Ga(0.6)As(0.986)N(0.014) QW and GaAs(1 - x)N(x) barrier and the increase of electronic leakage current. Finally, the temperature dependent electronic leakage current in the InGaAsN/GaAs(1 - x)N(x) quantum-well lasers are also investigated. (C) 2004 Elsevier B.V. All rights reserved.
Interconnect accelerating techniques for sub-100-nm gigascale systems
(2004-11-01)
Huang, HY
;
Chen, SL
;
電機學院
;
College of Electrical and Computer Engineering
This work describes new circuits called capacitor coupling trigger and capacitor coupling accelerator (CCA) circuits used to reduce the long interconnect RC delay in sub-100-nm processes. The proposed circuits use capacitors to split the output driving paths to eliminate the short-circuit current and thus improve the signal transition time. Besides, the capacitor coupling technique is applied to adjust the gate threshold voltage of the proposed circuits and isolate the input signal from the output driving transistors. The proposed circuits are faster than the prior circuits. Furthermore, the CCA can be applied to bi-directional interface, multiports bus, field-programmable gate array interconnections, and complex dynamic logic circuits.