Browsing by Issue Date, starting with "2003-06-01"

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Heterogeneous selection genetic algorithms for traveling salesman problems
(2003-06-01)
Tsai, HK
;
Yang, JM
;
Tsai, YF
;
Kao, CY
;
生物科技學系
This paper proposes a genetic algorithm, called the heterogeneous selection genetic algorithm (HSGA), integrating local and global strategies via family competition and edge similarity, for the traveling salesman problem (TSP). Local strategies include neighbor-join mutation and family competition, and global strategies consist of heterogeneous pairing selection and edge assembly crossover. Based on the mechanisms of preserving and adding edges, the search behaviors of neighbor-join mutation and edge assembly crossover are studied. The proposed method has been implemented and applied to 17 well-known TSPs whose numbers of cities range from 101 to 13,509. Experimental results indicate that this approach, although somewhat slower, performs very robustly and is very competitive with other approaches in the best surveys. This approach is able to find the optimum, and the average solution quality is within 0.00048 above the optima of each test problem.
Stability and formation of pyrochlore phase in doped Sr0.8Bi2.3Ta2O9 thin films
(2003-06-01)
Chen, SY
;
Lan, BC
;
Taso, CS
;
Lee, SY
;
材料科學與工程學系
Ferroelectric thin films of bismuth-containing layered perovskite Sr0.8Bi2.3Ta2-xMxO9 (SBTM), where M is V, Ti, W, and Zr. hake been prepared on Pt/Ti/SiO2/Si substrates using the metal-organic decomposition method. The effect of the incorporated B-site cations on pyrochlore phase formation and microstructure evolution of SBTM films was investigated. The pyrochlore phase formation has been identified due to out-diffusion of titanium from underneath platinum layer to participate in the reaction with the films. Furthermore, the formation of pyrochlore phase in the SBTM films has been observed strongly dependent on the characteristics of incorporated M cation. The substitution of both W and V for Ta leads to the formation of pyrochlore phase at lower annealing temperature (750-800 degreesC). On the other hand, the addition of Zr can retard the formation of pyrochlore phase from 850 to 900 degreesC. A model based on the binding energy of octahedral structure is used to elucidate the formation and stability of the pyrochlore phase present in the SBT film. (C) 2003 Elsevier Science B.V. All rights reserved.
High-current characterization of polysilicon diode for electrostatic discharge protection in sub-quarter-micron complementary metal oxide semiconductor technology
(2003-06-01)
Ker, MD
;
Chang, CY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Polysilicon diodes used in sub-quarter-micron complementary metal oxide semiconductor (CMOS) technologies are characterized by transmission line pulse (TLP) measurement to investigate device characteristics in a high-current regime. The second-breakdown current (I-t2) of the polysilicon diode shows good linear dependence on the device junction perimeter. When the polysilicon diodes are connected in a stacked configuration for reducing parasitic capacitance, the stacked polysilicon diodes show no degradation in electrostatic discharge (ESD) robustness compared with a single polysilicon diode. Such CMOS process-compatible polysilicon diodes have been successfully used as on-chip ESD protection devices for GHz radio-frequency (RF) circuits.
Interactivity and interactive functions in web-based learning systems: a technical framework for designers
(2003-06-01)
Chou, C
;
教育研究所
;
Institute of Education
The concept of interactivity and its implications for Web-based learning system design is re-examined. The author reviews the literature on the interactivity concept from the perspectives of communication, computer-assisted instruction, distance education, and interactive dimensions and functions for Web systems. A proposal is then made for a technical framework for including such dimensions and functions in Web-based learning systems. To enhance the framework's ease-of-use and overall effectiveness, each interactive function was submitted to two panels of experts for assessment and evaluation in terms of instructional necessity and programming difficulty. A discussion of the panels' feedback and the potential for future research concludes the article.
Anisotropic photoexcited carrier dynamics in (100)-, (001)-, and (110)-oriented YBCO films by polarized ultrafast optical spectroscopy
(2003-06-01)
Luo, CW
;
Chen, MH
;
Chiu, CC
;
Chen, SP
;
Wu, KH
We report the time-resolved ultrafast optical spectroscopy results obtained from a series of well characterized (001)-, (100)- and (110)-oriented YBa2Cu3O7-delta (YBCO) superconducting films prepared by pulsed laser deposition. The well-controlled film orientation has allowed us to probe the relaxation dynamics along various crystal orientations using respectively polarized pump and probe laser beams. The significant anisotropies in both the magnitude of the characteristic relaxation time and the temperature dependence of the photo-induced transient reflectance change indicate the nature of relaxation channel might be intrinsically different along different orientations. The implications of the results on the fundamental characteristics concerning superconducting gaps are discussed.
Decay rate and renormalized frequency shift of superradiant exciton in a cylindrical quantum wire
(2003-06-01)
Chen, YN
;
Chuu, DS
;
電子物理學系
;
Department of Electrophysics
The decay rate and renormalized frequency shift of superradiant exciton in a cylindrical quantum wire are studied. The transition behavior from 1D wire to 2D film is examined through the property of the radiative decay. Similar to the case in a quantum well, the decay rate of the higher mode exciton is larger than that of the lower mode one. Moreover, it is also found the decay rate and frequency shift do not show oscillatory dependence on wire radius because of the conservation of angular momentum. (C) 2003 Elsevier Science B.V. All rights reserved.
Microstructure and mechanical properties of surfactant templated nanoporous silica thin films: Effect of methylsilylation
(2003-06-01)
Chen, JY
;
Pan, FM
;
Cho, AT
;
Chao, KJ
;
Tsai, TG
Microstructural and mechanical properties of organic surfactant templated nanoporous thin silica films have been studied by X-ray diffraction, Fourier transform infrared spectroscopy, and nanoindentation. Compared with many other porous low-k dielectrics, the self-assembled molecularly templated nanoporous silica films demonstrate better mechanical properties. This is ascribed to the presence of a well-ordered pore channel structure in the nanoporous silica thin films. Hardness and elastic modulus are strongly dependent on film preparation and modification methods. Trimethylsilylation by hexamethylsilazane vapor treatment effectively enhances the mechanical strength of the nanoporous silica films. When the sol precursor solution is mixed with trimethylchlorosilane (TMCS), the resulting nanoporous films have a weaker mechanical strength. The pore channel structure of the nanoporous silica film becomes less ordered for the TMCS derivatized nanoporous films. In addition, the chemical structure in the silica solid matrix of the TMCS derivatized films is more disordered than those without TMCS modification. The nanoindentation measurement results are discussed in terms of the pore microstructure of the nanoporous silica network and the springback effect due to the presence of trimethylsilyl groups in the nanopores. (C) 2003 The Electrochemical Society.
A new BlueRing scatternet topology for Bluetooth with its formation, routing, and maintenance protocols
(2003-06-01)
Lin, TY
;
Tseng, YC
;
Chang, KM
;
資訊工程學系
;
Department of Computer Science
The basic networking unit in Bluetooth is piconet, and a larger-area Bluetooth network can be formed by multiple piconets, called scatternet. However, the structure of scatternets is not defined in the Bluetooth specification and remains as an open issue at the designers' choice. It is desirable to have simple yet efficient scatternet topologies with good supports of routing protocols, considering that Bluetooths are to be used for personal area networks with design goals of simplicity and compactness. In the literature, although many routing protocols have been proposed for mobile ad hoc networks, directly applying them poses a problem due to Bluetooth's special baseband and MAC-layer features. In this work, we propose an attractive scatternet topology called BlueRing, which connects piconets as a ring interleaved by bridges between piconets, and address its formation, routing, and topology-maintenance protocols. The BlueRing architecture enjoys the following fine features. First, routing on BlueRing is stateless in the sense that no routing information needs to be kept by any host once the ring is formed. This would be favorable for environments such as Smart Homes where computing capability is limited. Second, the architecture is scalable to median-size scatternets easily (e.g. around 50 similar to 70 Bluetooth units). In comparison, most star- or treelike scatternet topologies can easily form a communication bottleneck at the root of the tree as the network enlarges. Third, maintaining a BlueRing is an easy job even as some Bluetooth units join or leave the network. To tolerate single-point failure, we propose a protocol-level remedy mechanism. To tolerate multipoint failure, we propose a recovery mechanism to reconnect the BlueRing. Graceful failure is tolerable as long as no two or more critical points fail at the same time. As far as we know, the fault-tolerant issue has not been properly addressed by existing scatternet protocols yet. In addition, we also evaluate the ideal network throughput at different BlueRing sizes and configurations by mathematical analysis. Simulation results are presented, which demonstrate that BlueRing outperforms other scatternet structures with higher network throughput and moderate packet delay. Copyright (C) 2003 John Wiley Sons, Ltd.
Buoyancy driven vortex flow and thermal structures in a very low Reynolds number mixed convective gas flow through a horizontal channel
(2003-06-01)
Lin, TF
;
機械工程學系
;
Department of Mechanical Engineering
This paper starts with an overview of the buoyancy driven vortex flow and the associated thermal characteristics in low Reynolds number mixed convection of gas through a bottom heated horizontal plane channel. Various vortex flow patterns reported in the past decades from theoretical, experimental and numerical explorations are examined, including the longitudinal, transverse and mixed vortex rolls. The mixed vortex rolls exist in several forms and result from the merging and/or splitting of the longitudinal and transverse rolls which are simultaneously present in certain parameter ranges. Then, the buoyancy induced formation of the longitudinal and transverse vortex flows from the unidirectional forced convection dominated flow in the channel is illustrated. Besides, the vortex flow affected by the aspect ratio of the channel is also discussed. Moreover, the stabilization of the unstable vortex flow driven at very high buoyancy-to-inertia ratios through the top plate inclination, top plate heating and a surface-mounted rib is inspected. Furthermore, our recent results for the mixed convective vortex flow structures over a heated circular substrate are presented. Finally, directions for future research are pointed out according to the need for thin film vapor phase epitaxy frequently used in microelectronic fabrication. (C) 2003 Elsevier Science Inc. All rights reserved.
Waiting time distribution for the M/M/m queue
(2003-06-01)
Chan, WC
;
Lin, YB
;
資訊工程學系
;
Department of Computer Science
A novel method is presented for the calculation of the waiting time distribution function for the M/M/m queue. It is shown that the conditional waiting time obeys an Erlang distribution with rate mmu, where mu is the service rate of a server. An explicit closed form solution is obtained by means of the probability density function of the Erlang distribution. The derivation of the result proved to be very simple. The significance of Khintchine's method and its close relation to the proposed method is pointed out. It is also shown that the waiting time distribution can be obtained from Takacs's waiting time distribution for the G/M/m queue as a special case. This reveals some insight into the significance of Takacs's more general, but rather complex, result.
Dynamic behavior of ozonation with pollutant in a countercurrent bubble column with oxygen mass transfer
(2003-06-01)
Chen, YH
;
Chang, CY
;
Chiu, CY
;
Yu, YH
;
Chiang, PC
The dynamic behavior of ozonation with pollutants in a countercurrent bubble column is studied for the model establishment. Bubble columns have been widely used for an ozonation system in the plants and laboratories. In addition, a countercurrent bubble column has been commonly recommended than a cocurrent one because it has a higher ozone transfer efficiency. Therefore, the investigation of this paper focuses on the countercurrent bubble column. As an ozonation process starts, the gas mixture of ozone and oxygen is introduced into the bottom of a column, and then transferred into the liquid. The pollutants in the wastewater are eliminated subsequently via oxidation by the dissolved ozone. There certainly exists a temporary and unsteady period before the ozonation system reaches steady state. However, available ozonation models employed to describe ozone and pollutant profiles have commonly been developed for steady state. The treating qualities of wastewater in the early stage of ozonation are usually not predicted, and the time required for the steady-state establishment remains to be determined. Moreover, oxygen mass transfer is usually neglected in previous ozonation models so that the increase of dissolved oxygen is uncertain. These information is desirable for the proper design and operation of ozonation system in a bubble column. Thus, the aim of this study is to model and investigate the dynamic processes of ozonation with pollutants including oxygen mass transfer. The dynamic axial dispersion model proposed is employed to predict the variation of the ozone, pollutant, and oxygen concentrations profiles. The validity of the model was demonstrated by comparing the predicted results with the experimental data. The o-cresol was chosen as the model pollutant. The temporal concentration variations of the residual o-cresol and dissolved oxygen in the effluent liquid, and the off-gas ozone in the free volume were measured accordingly. Furthermore, the variation of the enhancement factor of ozone and the amount of off-gas were predicted. Note that it usually needs 2-5 hydraulic retention times to approach steady state under the conditions of this study. Further, the effects of dimensionless system parameters on the performance of the ozonation processes are examined. As a result, the proposed dynamic model of ozonation with pollutants is useful for proper prediction of the variables of an ozonation system in a countercurrent bubble column. (C) 2003 Elsevier Science Ltd. All rights reserved.
A Borrow-and-Return model to reduce client waiting time for broadcasting-based VOD services
(2003-06-01)
Yang, MH
;
Chang, CH
;
Tseng, YC
;
資訊工程學系
;
Department of Computer Science
One way to broadcast a popular video is to use multiple channels, each broadcasting a portion of the video periodically. Among the many schemes falling in this category, this paper focuses on several representative schemes (such as FB [15], [18], Pagoda [22], [24], and RFS [26]), which all share a FSFC property by repeatedly broadcasting the First Segment of the video on the First Channel. We propose a general Borrow-and-Return model that can be immediately applied to any scheme owning the FSFC property to reduce the viewer's waiting time without increasing the number of channels required. Given a group of videos, the basic idea is to lend the free time slots of videos without viewers to those videos with viewers to speedup the latter's transmission. By so doing, some bandwidth may be vacated by the borrowing videos to benefit others' transmission. Effectiveness of this model is analyzed by applying it to the FB scheme.
Optimization and implementation of piezoelectric radiators using the genetic algorithm
(2003-06-01)
Bai, MSR
;
Huang, CH
;
機械工程學系
;
Department of Mechanical Engineering
Very thin and small (45 mm x 35 mm x 0.35 mm) piezoelectric radiators have been developed in this research. The system is modeled by using the energy method in conjunction with the assumed-modes method. Electrical system, mechanical system, and acoustic loading have all been accounted for during the modeling stage. On the basis of the simulation model, the genetic algorithm (GA) is employed to optimize the overall configurations for a low resonance frequency and a large gain. The resulting designs are then implemented and evaluated experimentally. Performance indices for the experimental evaluation include the frequency response, the directional response, the sensitivity, and the efficiency. It is found in the experimental results that the piezoelectric radiators are able to produce comparable acoustical output with significantly less electrical input than the voice-coil panel speakers. (C) 2003 Acoustical Society of America.
Mechanism and modeling of ring pattern formation for electron beam exposure on Zwitterresist
(2003-06-01)
Chen, JK
;
Ko, FH
;
Chen, HL
;
Chang, FC
;
應用化學系
The novel sensitivity curve was determined for the zwitterresist. The irradiation dose in the center could create a ring pattern due to simultaneous exhibition of the positive tone and negative tone of zwitterresist. The natural logarithm dependence of ring width and electron beam dose was linear in two ranges, irrespective of the dot design radius. The heating effect was identified from 600 muC/cm(2), while it could be neglected at less than 600 muC/cm(2). Mathematical modeling for the prediction of ring width for zwitterresist, was achieved by considering the electron scattering and heating effects. The results of experimental measurement and modeling on ring width showed a very good correlation.
A floating well method for exact capacitance-voltage measurement of nano technology
(2003-06-01)
Su, HD
;
Chiou, BS
;
Wu, SY
;
Chang, MH
;
Lee, KH
Small gate area with short gate length reduces the C-V distortion of ultrathin oxide devices, but results in high parasitic capacitance/total capacitance ratio. The floating well method can exclude the parasitic capacitance to obtain accurate inversion oxide thickness without using any dummy pattern. It is suitable for nano technology.
Sensorless scalar-controlled induction motor drives with modified flux observer
(2003-06-01)
Wang, CC
;
Fang, CH
;
電控工程研究所
;
Institute of Electrical and Control Engineering
This paper presents a simple sensorless scalar control algorithm to control the speed of an induction motor. First, a modified flux observer was employed to estimate the stator flux with the voltage command and the feedback current. Then, based on the mathematical model of the induction motor, the slip frequency was calculated, and the frequency of the voltage command was compensated. An auto-boost controller was designed to overcome the decrease in voltages of the stator resistance and to maintain constant stator flux amplitude. To improve the pure integration problem, a highpass filter was installed in the stator flux observer. In this filter, the cut-off frequency is proportional to the voltage frequency; therefore, the phase shift and amplitude degradation of the estimated flux can be corrected easily. Finally, to demonstrate the proposed control algorithm, a PC-based experimental system was constructed in a 1-hp induction motor. Experimental results are presented to validate the effectiveness of our design.
Modeling the binding and inhibition mechanism of nucleotides and sulfotransferase using molecular docking
(2003-06-01)
Lin, ES
;
Yang, JM
;
Yang, YS
;
生物科技學系
;
生物資訊及系統生物研究所
Phenol sulfotransferase (PST) catalyzes sulfuryl group transfer from adenosine 3'-phosphate 5'-phosphosulfate (PAPS) to a variety of nucleophilic acceptors in biological systems. Physiological sulfation by PAPS results in the production of adenosine 3',5'-diphosphate (PAP). PAP may become a strong inhibitor or cofactor for the physiological or the transfer reactions, respectively. Several nucleotides other than, PAP also serve as substrates, inhibitors or cofactors of PST catalyzed reactions. We are interested in the effects of these nucleotides on the PST catalyzed reactions and their possible physiological significance in biology. Several nucleotide inhibitors (such as adenosine 5'-diphosphate and adenosine 5'-triphosphate) of sulfotransferase in physiological reactions have been reported in the literature. However, our data suggests that they are not inhibitors for the transfer reaction or the reverse physiological reaction catalyzed by PST. The aim of this work is to show that the molecular docking analysis can be successfully used to underline the inhibition mechanism of these nucleotides. First, the selected compounds were subjected to a detailed docking analysis, by means of GEMDOCK, a program able to reveal the most likely binding mode for each ligand. By comparing these results with binding sites and binding compounds of the nucleotides with known X-ray structures, it is possible to highlight the site specificity and the inhibition mechanism of the select compounds. The results obtained by the above algorithm were further confirmed experimentally. In this paper, we show the effect of a variety of nucleotides on the activity of sulfotransferase in different docking conditions.
Guest editorial: Special section on wireless Internet
(2003-06-01)
Lin, YB
;
Tseng, YC
;
交大名義發表
;
National Chiao Tung University
Robust H(infinity) control problem for general nonlinear systems with uncertainty
(2003-06-01)
Wu, JL
;
Lee, TT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, both state and output feedback robust H(infinity) control problems for general nonlinear systems with norm-bound uncertainty are considered. Sufficient conditions for the existence of robust output feedback H(infinity) controller are provided. State space formulas for robust H(infinity) output controller are provided.
Study of electrical discharge grinding using metal matrix composite electrodes
(2003-06-01)
Shu, KM
;
Tu, GC
;
材料科學與工程學系
;
Department of Materials Science and Engineering
An investigation was made into the combined technologies of electrical discharge machining and grinding (EDMG). A metal matrix (Cu/SiCp) electrode with a rotating device was made and employed to study the EDMG technology. It was found that 3-7 times the normal electrical discharge machining (EDM) material removal rate (MRR) could be achieved in EDMG under suitable conditions of electrode rotating speed, SiCp particle size and current. This novel achievement is attributed to the fact that, under appropriate conditions, the hump-shaped melted material created by the EDM mechanism is vulnerable to attack by the grinding mechanism during the EDMG operation, greatly increasing the removal rate. Conversely, under inappropriate conditions, in which hump-shaped material solidifies prior to the non-conductive ceramic particle grinding, the above function becomes negligible and results in much lower MRR. (C) 2003 Elsevier Science Ltd. All rights reserved.