Browsing by Issue Date, starting with "1996-09-30"

Now showing 1 - 20 of 85060

Synthesis of sulfone-substituted thiophene chromophores for second-order nonlinear optics
(1996-09-30)
Chou, SSP
;
Sun, DJ
;
Huang, JY
;
Yang, PK
;
Lin, HC
A new series of conjugated thiophene compounds 1-4 containing methylsulfonyl and phenylsulfonyl accepters have been synthesized which possess efficient second-order optical nonlinearities, high thermal stability and good transparency for use as nonlinear optical materials. Copyright (C) 1996 Elsevier Science Ltd
A raster-based C program for siting a landfill with optimal compactness
(1996-10-01)
Kao, JJ
;
交大名義發表
;
環境工程研究所
;
National Chiao Tung University
;
Institute of Environmental Engineering
Landfill siting requires performing spatial analyses for various factors to evaluate site suitability. A geographical information system, although capable of effectively manipulating spatial data, lacks the capability to locate an optimal site when compactness and other factors are considered simultaneously. In our previous work, a mixed-integer compactness model was proposed to overcome this difficulty. However, computational time with a conventional mixed-integer programming package for solving the model is time consuming and impractical. Therefore, in this work, a C program is developed, based on a proposed raster-based branch-and-bound algorithm. The program can implement multi-factor analyses for compactness and other siting factors with weights prespecified by the user. An example is provided to demonstrate the effectiveness of the program. Copyright (C) 1996 Elsevier Science Ltd
NPS model parameter uncertainty analysis for an off-stream reservoir
(1996-10-01)
Kao, JJ
;
Hong, HJ
;
環境工程研究所
;
Institute of Environmental Engineering
Parameter uncertainties exert a significant effect on nonpoint source pollution (NPS) modeling results. A decision made on the basis of such results may thereby be inappropriate. In this work, the parameter uncertainty is analyzed to explore an improved modeling procedure. Drainage patterns generated from digital elevation data and rainfall are the major parameters examined. A case study for the watershed of the Posan off-stream reservoir is implemented. A significant spatial variation of NPS distribution simulated with a drainage pattern generated from varied methods is observed. The effects of rainfall randomness on the spatial loading distribution are assessed and computed based on a Monte Carlo simulation. The proposed procedure is capable of improving the quality of modeling results and the decision for an appropriate control strategy.
Kinetics of hydrogen sulfide oxidation by immobilized autotrophic and heterotrophic bacteria in bioreactors
(1996-10-01)
Chung, YC
;
Huang, CP
;
Tseng, CP
;
環境工程研究所
;
生物科技學系
The kinetics of H2S oxidation in bioreactors with separately packed autotrophic Thiobacillus thioparus CH11 and heterotrophic Pseudomonas putida CH11 were evaluated. The reaction rates were determined to be first-order below 20 ppm, zero-order above 60 ppm, and fractional-order in the intermediate concentration ranges for the Thiobacillus thioparus CH11 bioreactor, the first-order below 35 ppm, zero-order above 80 ppm, and fractional-order in the intermediate concentration ranges for the Pseudomonas putida CH11 bioreactor. The saturation constants for H2S by Thiobacillus thioparus CH11 and Pseudomonas putida CH11 were calculated to be 30.3 ppm and 44.2 ppm, respectively.
Exploiting communication complexity for Boolean matching
(1996-10-01)
Wang, KH
;
Hwang, TT
;
Chen, C
;
資訊工程學系
;
Department of Computer Science
Boolean matching is to check the equivalence of two functions under input permutation and input/output phase assignment, A straightforward implementation takes time complexity O(n!(n)2), where n is the number of variables, Various signatures of variables were used to prune impossible permutations by many researchers. In this paper, based on communication complexity, we also propose two signatures, cofactor and equivalence signatures, which are general forms of many existing signatures, These signatures are used to develop an efficient Boolean matching algorithm which is based on checking structural equivalence of OBDD's. Experimental results on a set of benchmarks show that our algorithm is indeed very effective in solving Boolean matching problem.
Exploiting communication complexity for Boolean matching
(1996-10-01)
Wang, KH
;
Hwang, TT
;
Chen, C
;
資訊工程學系
;
Department of Computer Science
Boolean matching is to check the equivalence of two functions under input permutation and input/output phase assignment, A straightforward implementation takes time complexity O(n!(n)2), where n is the number of variables, Various signatures of variables were used to prune impossible permutations by many researchers. In this paper, based on communication complexity, we also propose two signatures, cofactor and equivalence signatures, which are general forms of many existing signatures, These signatures are used to develop an efficient Boolean matching algorithm which is based on checking structural equivalence of OBDD's. Experimental results on a set of benchmarks show that our algorithm is indeed very effective in solving Boolean matching problem.
Technology mapping for FPGAs with composite logic block architectures
(1996-10-01)
Chuang, HH
;
Shung, CB
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A new technology mapping algorithm is developed on a general model of FPGA with composite logic block architectures consisting of different sizes of look-up tables (LUTs) and possibly different logic gates. In additions, the logic blocks may have hard-wired connections and limit accessible fanouts. Xilinx XC4000 is one one example containing LUTs of different sizes and AT&T ORCA is another example containing both LUTs and logic gates. We use a multiple-fanout pattern graph library to model the composite logic block and a premapping technique to generate the subject graph dynamically. A new matching algorithm and a new covering algorithm are also developed for the subject graph covering. The experimental results show that our algorithm is an effective technology mapper for FPGAs with composite logic block architectures, especially for large circuits. Over a set of MCNC benchmarks, our algorithm requires on the average 4.25% few CLBs than PPR, 6.79% fewer CLBs than TEMPT, and 2.79% fewer CLBs than ASYL when used as the XC4000 mapper. Over a set of larger benchmarks, our algorithm outperforms PPR by 13.70%. Very encouraging results were obtained when our algorithm is used as an ORCA mapper, while there was no prior published results.
Maneuvering target tracking with colored noise
(1996-10-01)
Wu, WR
;
Chang, DC
;
交大名義發表
;
電信工程研究所
;
National Chiao Tung University
It is known that colored noise may degrade the performance of a tracking algorithm. A common remedy is to model colored noise as an autoregressive (AR) process and apply the measurement difference method One problem with the approach is that the AR parameters are usually unknown. In this work, we propose a new method to adaptively estimate the AR parameters. It is shown that this method is simple and practically feasible. We incorporate our method into the interacting multiple model (IMM) tracking algorithm and show that the performance is almost as good as that in the known parameters case.
NPS model parameter uncertainty analysis for an off-stream reservoir
(1996-10-01)
Kao, JJ
;
Hong, HJ
;
交大名義發表
;
環境工程研究所
;
National Chiao Tung University
Parameter uncertainties exert a significant effect on nonpoint source pollution (NPS) modeling results. A decision made on the basis of such results may thereby be inappropriate. In this work, the parameter uncertainty is analyzed to explore an improved modeling procedure. Drainage patterns generated from digital elevation data and rainfall are the major parameters examined. A case study for the watershed of the Posan off-stream reservoir is implemented. A significant spatial variation of NPS distribution simulated with a drainage pattern generated from varied methods is observed. The effects of rainfall randomness on the spatial loading distribution are assessed and computed based on a Monte Carlo simulation. The proposed procedure is capable of improving the quality of modeling results and the decision for an appropriate control strategy.
A raster-based C program for siting a landfill with optimal compactness
(1996-10-01)
Kao, JJ
;
環境工程研究所
;
Institute of Environmental Engineering
Landfill siting requires performing spatial analyses for various factors to evaluate site suitability. A geographical information system, although capable of effectively manipulating spatial data, lacks the capability to locate an optimal site when compactness and other factors are considered simultaneously. In our previous work, a mixed-integer compactness model was proposed to overcome this difficulty. However, computational time with a conventional mixed-integer programming package for solving the model is time consuming and impractical. Therefore, in this work, a C program is developed, based on a proposed raster-based branch-and-bound algorithm. The program can implement multi-factor analyses for compactness and other siting factors with weights prespecified by the user. An example is provided to demonstrate the effectiveness of the program. Copyright (C) 1996 Elsevier Science Ltd
Using asynchronous writes on metadata to improve file system performance
(1996-10-01)
Feng, LC
;
Chang, RC
;
資訊工程學系
;
Department of Computer Science
Due to the increasing gap between CPU and disk I/O speeds, the file system is becoming the performance bottleneck in computer system design. How to improve file system performance is increasingly important. There are two types of entities in a file system: data and metadata. Data mean the actual contents of files. Metadata include access control and other descriptive information about files. Previous research indicates that metadata writes account for 38 - 40% of disk I/O operations. These large numbers of control request I/Os are usually ignored in traditional file system study, which concentrates only on file-level access patterns. We propose the design and implementation of a metadata-ordering mechanism and its corresponding asynchronous write facility. With such a facility, we can eliminate many synchronous metadata writes, and have the flexibility of choosing a better way to update these metadata modifications to disk asynchronously. Extensive performance evaluation shows that substantial performance improvement can be achieved under various benchmarks. Some other tests are also used to demonstrate the benefits and behaviors of this approach.
A note on integrability in matrix models
(1996-10-01)
Tu, MH
;
Shaw, JC
;
Yen, HC
;
應用數學系
;
Department of Applied Mathematics
Based on the bilinear relation approach, we show that the hermitian one-matrix model at finite N can be embedded into 1d Toda chain and (modified) KP hierarchy respectively with the same Wronskian-type tau function. We also point out that which hierarchy to take depends on the choice of the wave function for constructing the bilinear relation.
Quantitative feedback design of uncertain multivariable control systems
(1996-10-01)
Cheng, CC
;
Liao, YK
;
Wang, TS
;
電控工程研究所
;
Institute of Electrical and Control Engineering
An alternative QFT framework is proposed for the design of multiple-input multiple-output (MIMO) feedback systems with significant plant uncertainty. Sufficient conditions are first derived to assure the achievement of the given off-diagonal performance. Then the given performance bounds on each main channel are re-allocated on a reasonable basis, such that not only is the main channel performance easily achieved, but also the trade-offs of performance bounds between the loops become transparent during the system synthesis.
A note on integrability in matrix models
(1996-10-01)
Tu, MH
;
Shaw, JC
;
Yen, HC
;
應用數學系
;
Department of Applied Mathematics
Based on the bilinear relation approach, we show that the hermitian one-matrix model at finite N can be embedded into 1d Toda chain and (modified) KP hierarchy respectively with the same Wronskian-type tau function. We also point out that which hierarchy to take depends on the choice of the wave function for constructing the bilinear relation.
Adaptive subsethood for neural fuzzy control
(1996-10-01)
Lin, CT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
The paper extends Kosko's fuzzy measure of subsethood (Kosko 1992) to a measure of mutual subsethood or fuzzy equivalence. Gaussian or bell-shaped fuzzy sets then simplify the new measure and allow supervised learning to learn and tune the fuzzy rules. The gaussian sets act as nodes in neural fuzzy control networks and give a simple closed form for the measure of mutual subsethood. The new adaptive subsethood controller (ASC) system uses the network structure to store, learn, and tune fuzzy rules. Simulations show how the ASC system can control a model car, balance an inverted wedge, and control the ball and beam system.
Effects of growth temperature on solid incorporation of AlAs1-xSbx using tertiarybutylarsine as arsenic source precursor
(1996-10-01)
Chen, WK
;
Ou, JH
;
Hsu, CH
;
交大名義發表
;
電子物理學系
We have investigated the effects of growth temperature on the solid incorporation of AlAsSb epilayers grown LJ metalorganic vapor-phase epitaxy using TMAl, TBAs and TMSb as source precursors. The solid incorporation of AlAsSb was found to be strongly affected by the pyrolysis reactions and kinetics of the source precursors, in particular, TMAl and TBAs. Our experimental results indicated that the, Al incorporation efficiency increases with the growth temperature and saturates at temperatures above similar to 625 degrees C. On the other hand, the growth behavior of As is anomalous: the As incorporation efficiency increases initially with growth temperature, and decreases monotonously at temperatures above similar to 550 degrees C. The reduced As incorporation efficiency at high temperatures may be closely related to the beta-elimination process of TBAs, and to the formation of adducts in the gas phase.
Using asynchronous writes on metadata to improve file system performance
(1996-10-01)
Feng, LC
;
Chang, RC
;
資訊工程學系
;
Department of Computer Science
Due to the increasing gap between CPU and disk I/O speeds, the file system is becoming the performance bottleneck in computer system design. How to improve file system performance is increasingly important. There are two types of entities in a file system: data and metadata. Data mean the actual contents of files. Metadata include access control and other descriptive information about files. Previous research indicates that metadata writes account for 38 - 40% of disk I/O operations. These large numbers of control request I/Os are usually ignored in traditional file system study, which concentrates only on file-level access patterns. We propose the design and implementation of a metadata-ordering mechanism and its corresponding asynchronous write facility. With such a facility, we can eliminate many synchronous metadata writes, and have the flexibility of choosing a better way to update these metadata modifications to disk asynchronously. Extensive performance evaluation shows that substantial performance improvement can be achieved under various benchmarks. Some other tests are also used to demonstrate the benefits and behaviors of this approach.
Network expert geographic information system for landfill siting
(1996-10-01)
Kao, JJ
;
Chen, WY
;
Lin, HY
;
Guo, SJ
;
環境工程研究所
A prototypical network expert geographic information system (GIS) is developed to facilitate municipal solid waste landfill siting. A forward chaining knowledge base consisting of related siting rules extracted from various literature is used to establish an expert system. Siting analysis is performed by a GIS and evaluated by rules triggered from the expert system. The expert system and GIS are integrated into an expert GIS to combine the advantages of both systems. Also, a multimedia network interface is designed for local or remote access to the system from anywhere on the Internet. With the interface, a general user does not require previous knowledge of the expert system and GIS to use the system. This networking capability not only significantly reduces the cost of distributing tools to each user, but also avoids the difficulty that each user may encounter in installing and managing tools on the computer. Finally, a case study is provided to demonstrate the effectiveness of the developed system in facilitating landfill-siting analysis. The system can be directly accessed via Internet from the home page http://ev004.ev.nctu.edu.tw/ENGLISH/wsite/index.html.
Network expert geographic information system for landfill siting
(1996-10-01)
Kao, JJ
;
Chen, WY
;
Lin, HY
;
Guo, SJ
;
交大名義發表
A prototypical network expert geographic information system (GIS) is developed to facilitate municipal solid waste landfill siting. A forward chaining knowledge base consisting of related siting rules extracted from various literature is used to establish an expert system. Siting analysis is performed by a GIS and evaluated by rules triggered from the expert system. The expert system and GIS are integrated into an expert GIS to combine the advantages of both systems. Also, a multimedia network interface is designed for local or remote access to the system from anywhere on the Internet. With the interface, a general user does not require previous knowledge of the expert system and GIS to use the system. This networking capability not only significantly reduces the cost of distributing tools to each user, but also avoids the difficulty that each user may encounter in installing and managing tools on the computer. Finally, a case study is provided to demonstrate the effectiveness of the developed system in facilitating landfill-siting analysis. The system can be directly accessed via Internet from the home page http://ev004.ev.nctu.edu.tw/ENGLISH/wsite/index.html.
Photoluminescence from ordered and disordered Si-SiGe superlattices
(1996-10-01)
Chang, TC
;
Yeh, WK
;
Mei, YJ
;
Tsai, WC
;
Chen, YF
Ordered (Ord-SL) and disordered (Dis-SL) Si-SiGe superlattices are grown using ultrahigh vacuum chemical vapour deposition (UHVCVD). The results of cross-sectional transmission electron microscopy (XTEM) and high-resolution double crystal x-ray diffraction (HRXRD) indicate that high quality Si-SiGe superlattices can be achieved. Well-defined band-edge excitonic luminescence is observed for the Si0.86Ge0.14-Si superlattice. Stronger phosoluminescence (PL) is observed for the Si-SiGe disordered superlattice compared with the corresponding Si-SiGe ordered superlattice. Furthermore, PL peak energy of the Dis-SL shifts to lower value with respect to the peak position of the corresponding Ord-SL. The stronger intensity of the no-phonon (NP) peak and the red shift of the PL peak are possibly a result of two probable mechanisms: (i) the tunnelling effect and (ii) the formation of localized states.