Browsing by Issue Date, starting with "2004-11-01"

Now showing 1 - 20 of 69301

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.
Thermal gradient in solder joints under electrical-current stressing
(2004-11-01)
Shao, TL
;
Chiu, SH
;
Chen, C
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Yao, DJ
;
Hsu, CY
The thermal gradient and temperature increase in SnAg3.5 solder joints under electrical-current stressing have been investigated by thermal infrared microscopy. Both positive and negative thermal gradients were observed under different stressing conditions. The magnitude of the thermal gradient increases with the applied current. The measured thermal gradients reached 365degreesC/cm as powered by 0.59 A, yet no obvious thermal gradient was observed when the joints were powered less than 0.25 A. The temperature increase caused by joule heating was as high as 54.5degreesC when powered by 0.59 A, yet only 3.7degreesC when stressed by 0.19 A. The location of heat generation and path of heat dissipation are believed to play crucial roles in the thermal gradient. When the major heat source is the Al trace, the thermal gradient in the solder bumps is positive; but it may become negative because the heat generated in the solder itself is more prominent.
雙觸發矽控整流元件與使用其之靜電保護電路
(2004-11-01)
柯明道
;
徐國鈞
一種雙觸發矽控整流元件與使用其之靜電保護電路。此種雙觸發矽控整流元件係在一個P型基底中配置了數個 N+擴散區域、數個P+擴散區域、第一N型井區域、第二N型井區域和第三N型井區域。每一個N+擴散區域和P+擴散區域中間，都以淺溝渠結構加以隔離。在P+擴散區域內的其中二個，係雙觸發矽控整流元件的P型觸發區。而在N+擴散區域內的其中二個，係雙觸發矽控整流元件的N型觸發區。
A Lagrangean relaxation-based approach for routing and wavelength assignment in multigranularity optical WDM networks
(2004-11-01)
Lee, SSW
;
Yuang, MC
;
Tien, PL
;
Lin, SH
;
資訊工程學系
Optical wavelength-division multiplexed (WDM) networks often include optical cross-connects with multigranularity switching capability such as switching on a single lambda, a waveband, or an entire fiber basis. In addition, it has been shown that routing and wavelength assignment (RWA) in an arbitrary mesh WDM network is an NP-complete problem. In this paper, we propose an efficient approximation approach, called Lagrangean relaxation with heuristics (LRH), aimed to resolve RWA in multigranularity WDM networks particularly with lambda and fiber switches. The task is first formulated as a combinatorial optimization problem in which the bottleneck link utilization is to be minimized. The LRH approach performs constraint relaxation and derives a lower-bound solution index according to a set of Lagrangean multipliers generated through subgradient-based iterations. In parallel, using the generated Lagrangean multipliers, the LRH approach employs a new heuristic algorithm to arrive at a near-optimal upper-bound solution. With lower and upper bounds, we conduct a performance study on LRH with respect to accuracy and convergence speed under different parameter settings. We further draw comparisons between LRH and an existing practical approach via experiments over randomly generated and several well-known large sized networks. Numerical results demonstrate that LRH outperforms the existing approach in both accuracy and computational time complexity, particularly for larger sized networks.
Simulation analysis and experimental verification of LIGA-like process for Ni-Fe micromold insert with taper angle
(2004-11-01)
Fu, MN
;
Yeh, YM
;
Tu, GC
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The LIGA (a German acronym for lithographic, gavanoformung, abformung) (or LIGA-like) process involving lithography, electroforming, and molding is one of the most important microfabrication technologies for fabricating high-aspect-ratio 3-D microstructures. In this study we use CFX software to simulate the flow field in the micromold insert electroforming process and investigate the mass transfer effect, as well as the flow field and mass transfer for different taper angles and aspect ratios for a microtemplate under different flow speeds, in order to understand the effect of the geometrical shape of the template on the electroforming process, thus to obtain the optimum physical electroforming model. In this study, we will also perform a practical electroforming process at different aspect ratios and different taper angles of the microtemplate, in order to verify the results of the simulation. From the results of the simulation, it is found that the taper angle increases the speed of the plating solution at the vent, and a good equilibrium is achieved at a taper angle of 30degrees-45degrees. Since taper angle significantly affects the mass transfer effect, it can be used to increase the mass transfer effect in high-aspect-ratio and small holes. This result has been verified using a practical electroforming Ni-Fe micromold insert.
Analysis of instability line width and white wall created by the photolithography process
(2004-11-01)
Kuo, YK
;
Chao, CG
;
Lin, CY
;
材料科學與工程學系
;
Department of Materials Science and Engineering
In the photolithography processing of semiconductor, line width is smaller and smaller. Therefore, the requirements of process window are stricter than before. In the small line width, the formation of serious white wall will affect line width and cause rejects in following process. The study conducted research on the control of best focus in which particularly explored the relationship between exposure dose and line width and the phenomenon of white wall generated by focus. The research obtained related coefficients of exposure dose-line width and exposure dose-white wall by coating photo resist of different components with the same thickness on the surface of fused silica wafer. The results of research found that exposure dose might not only change line width but also had important effects on white wall. Among others, the most important factor for exposure dose is the component of sensitivity of photo resist. (C) 2004 Elsevier Ltd. All rights reserved.
QoS Scheduler/Shaper for optical coarse packet switching IP-over-WDM networks
(2004-11-01)
Yuang, MC
;
Tien, PL
;
Shih, J
;
Chen, A
;
資訊工程學系
For IP-over-WDM networks, optical coarse packet switching (OCPS) has been proposed to circumvent optical packet switching limitations by using in-band-controlled per-burst switching and advocating traffic control enforcement to achieve high bandwidth utilization and quality-of-service (QoS). In this paper, we first introduce the OCPS paradigm. Significantly, we present a QoS-enhanced traffic control scheme exerted during packet aggregation at ingress nodes, aiming at providing delay and loss class differentiations for OCPS networks. Serving a dual purpose, the scheme is called (psi, tau)-Scheduler/Shaper, where psi and tau are the maximum burst size and burst assembly time, respectively. To provide delay class differentiation, for IP packet flows designated with delay-associated weights, (psi, tau)-Scheduler performs packet scheduling and assembly into bursts based on their weights and a virtual window of size psi. The guaranteed delay bound for each delay class is quantified via the formal specification of a stepwise service curve. To provide loss class differentiation, (psi, tau)-Shaper facilitates traffic shaping with larger burst sizes assigned to higher loss priority classes. To examine the shaping effect on loss performance, we analytically derive the departure process of (psi, tau)-Shaper. The aggregate packet arrivals are modeled as a two-state Markov modulated Bernoulli process (MMBP) with batch arrivals. Analytical results delineate that (psi, tau)-Shaper yields substantial reduction, proportional to the burst size, in the coefficient of variation of the burst interdeparture time. Furthermore, we conduct extensive simulations on a 24-node ARPANET network to draw packet loss comparisons between OCPS and just-enough-time (JET)-based OBS. Simulation results demonstrate that, through burst size adjustment, (psi, tau)-Shaper effectively achieves differentiation of loss classes. Essentially, compared to JET-based OBS using out-of-band control and offset-time-based QoS strategy, OCPS is shown to achieve invariably superior packet loss probability for a high-priority class, facilitating better differentiation of loss traffic classes.
Nanoflash device with self-aligned double floating gates using scanning probe lithography and tetramethylammonium hydroxide wet etching
(2004-11-01)
Sheu, JT
;
Chen, CC
;
You, KS
;
Tsai, ST
;
材料科學與工程學系奈米科技碩博班
We report a self-aligned technology for nanoflash devices with double floating gates using scanning probe lithography (SPL) technology and anisotropic wet etching. On a (110) SOI silicon wafer, along [001] and [111] directions, a silicon nanowire was generated through local oxidation with SPL followed by wet etching with tetramethylammonium hydroxide solution. Silicon nanowires (SiNW) with profiles of sidewall either sloped or vertical were formed after anisotropic etching in the [001] or [111] direction respectively. After deposition of a polysilicon film on the SiNW with low pressure chemical vapor deposition, nanostructures of a nanoflash device with polysilicon double-floating side gates were obtained along the [111] part of SiNW after reactive ion etching spacer etching. The silicon nanowire channel has a width of 20 nm and a height of 200 rim; the width of the self-aligned floating gate is approximately 40 rim. Silicon nitride was deposited to serve as gate dielectric. The top gate and source-drain aluminum pads were defined by photo litholgraphy. Electrical properties of such a nanoflash device with double-floating side gates are discussed. (C) 2004 American Vacuum Society.
Modeling and analysis of acoustic musical strings using Kelly-Lochbaum lattice networks
(2004-11-01)
Liang, SF
;
Su, AWY
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Musical strings play important roles in the timbre of a stringed instrument. An instrument installed with different strings can produce very different sounds. To model a plucked-string instrument physically, analyzing its strings may be a good starting point. In this paper, a novel strategy for the modeling and analysis of acoustic musical strings is proposed. In order to obtain the vibration of an acoustic string, a measurement device with multiple sets of electromagnetic pickups is built. A recurrent network based on the Kelly-Lochbaum structure with multiple sets of system parameters is proposed to simulate the time-varying vibrating behavior of a target string. A fast training algorithm combining BPTT and SARPROP is also proposed to train the network automatically. The well-trained recurrent network based model can be regarded as a close simulation model of a real string, and using the model, it becomes easier to understand the characteristics of a string under different conditions when it vibrates.