Browsing by Issue Date, starting with "1994-03-01"

Now showing 1 - 20 of 88409

管管作品兩首
(1994-03-01)
管管
NOVEL SUPERVISORY TECHNIQUE USING WAVELENGTH-DIVISION-MULTIPLEXED OTDR IN EDFA REPEATERED TRANSMISSION-SYSTEMS
(1994-03-01)
LAI, YW
;
CHEN, YK
;
WAY, WI
;
電信工程研究所
;
光電工程學系
A wavelength-division-multiplexed optical-time-domain-reflectometry (OTDR) supervisory technique is experimentally demonstrated in a 200-km transmission system. The technique can simultaneously achieve in-line EDFA performance monitoring and diversity protection, and fault location in optical fibers.
PATH FEASIBILITY AND MODIFICATION BASED ON THE PUMA 560 WORKSPACE ANALYSIS
(1994-03-01)
SHAO, KC
;
YOUNG, KY
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Robot paths are planned according to different industrial tasks. Their kinematic feasibility is restrained by the structure of the given robot manipulator. In order to design feasible paths under kinematic constraints and different task requirements, we propose first to utilize the geometry of the given robot to generate the geometric boundaries of different regions corresponding to kinematic constraints in the robot workspace. Geometric expressions are then derived to describe the relationship about the planned path and the robot workspace. Finally, by applying the developed modification strategies based on different task requirements, feasible paths can be obtained by modifying the infeasible portions of the paths. To demonstrate the proposed feasibility and modification schemes, the PUMA 560 robot manipulator is selected as a case study due to its complexity and practical application. The results are then extended to general wrist-partitioned types of industrial robot manipulators.
A NEW GLOBAL APPROACH FOR 0-1 POLYNOMIAL PROGRAMS
(1994-03-01)
LI, HL
;
交大名義發表
;
資訊管理與財務金融系註：原資管所+財金所
;
National Chiao Tung University
;
Department of Information Management and Finance
Given a 0-1 polynomial expression SIGMA(k=1)N-1 SIGMA(m=k+1)N x(k)x(m), where x(k) and x(m) are 0-1 variables, the famous Glover and Woolsey method required to use N(N - 1)/2 additional continuous variables and 2N(N - 1) linear constraints to transform this expression into a linear form. This paper proposes a method which first reformulates the above expression as a new expression SIGMA(k=1)N x(k)y(k), y(k) = SIGMA(m=k+1)N x(m); then to transform the expression into a linear form where x(k) and y(k) are separated. The proposed transformation method only required to use 2(N - 1) additional continuous variables and 8(N - 1) linear constraints. Based on the new transformation, a 0-1 polynomial program can be more effectively solved to obtain a global optimum.
CONSIDERING THE EFFECT OF BODY FORCE FOR REGIONAL LAND DISPLACEMENTS
(1994-03-01)
LU, RH
;
YEH, HD
;
土木工程學系
;
環境工程研究所
;
Department of Civil Engineering
In this study, a general mathematical model was developed for land displacements that occur as a result of the pressure decline in confined and/or phreatic aquifers. Two equations were developed by employing the equilibrium (force balance) equation and the flow equation in a deforming aquifer system. Both of these equations were integrated over the thickness of the aquifer system once a regional model had been formulated. The change of the body force in saturated and unsaturated zones of aquifers was considered in the derivation of the equilibrium equation. It was assumed that no external loading or force acting on the aquifer system was present. Two coupled equations expressed in terms of the averaged dilation and pressure were then obtained. The pumping data sets given in the papers of Bear and Corapcioglu1,2 in 1981 and 1983 were analysed. Drawdown and displacements in a confined aquifer were demonstrated to be identical to those estimated by Bear and Corapcioglu.1 In the case of a phreatic aquifer, however, the results estimated by the present approach were slightly different from those obtained by Corapcioglu and Bear.2 The discrepancies in the results are possibly due to errors in the equations presented by Corapcioglu and Bear.2 The present approach was able to avoid several assumptions and complex procedures used by Bear and Corapcioglu,1,2 especially in the case of a phreatic aquifer, by taking into account the change in the body force.
PATH FEASIBILITY AND MODIFICATION BASED ON THE PUMA 560 WORKSPACE ANALYSIS
(1994-03-01)
SHAO, KC
;
YOUNG, KY
;
交大名義發表
;
電控工程研究所
;
National Chiao Tung University
Robot paths are planned according to different industrial tasks. Their kinematic feasibility is restrained by the structure of the given robot manipulator. In order to design feasible paths under kinematic constraints and different task requirements, we propose first to utilize the geometry of the given robot to generate the geometric boundaries of different regions corresponding to kinematic constraints in the robot workspace. Geometric expressions are then derived to describe the relationship about the planned path and the robot workspace. Finally, by applying the developed modification strategies based on different task requirements, feasible paths can be obtained by modifying the infeasible portions of the paths. To demonstrate the proposed feasibility and modification schemes, the PUMA 560 robot manipulator is selected as a case study due to its complexity and practical application. The results are then extended to general wrist-partitioned types of industrial robot manipulators.
AN AUTHENTICATION-COMBINED ACCESS-CONTROL SCHEME USING A ONE-WAY FUNCTION
(1994-03-01)
WU, TC
;
CHANG, CC
;
YEH, YS
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
In this paper, we propose an authentication-combined access control scheme for information protection systems. Let a(ij) be the access privilege of User i to File j. Initially, by the Diffie-Hellman public key distribution scheme, the system and the users are assigned distinct secret keys, and their corresponding public keys, respectively. Let K(s) be the secret key and y(s) be the public key of the system, and let K(i) be the secret key and y(i) be the public key of the User i. By using a predefined one-way function F, we compute r(ij) = F(K(i), y(s), a(ij)). Reversely, the access privilege can be retained as a(ij) = F(K(s), y(i), r(ij)). Being different from the previously proposed schemes, our scheme is safer and the user's secret key is used not only for computing the corresponding access privilege to the intended file, but also for authenticating the requesting user not to illegitimately access the protected files. The proposed scheme is simple to establish. Besides, it can perform the access control in dynamic environments, such as change access privileges and insert/delete users or files.
THE CAST STRUCTURE OF A 7075 ALLOY PRODUCED BY A WATER-COOLING CENTRIFUGAL CASTING METHOD
(1994-03-01)
YEH, JW
;
JONG, SH
;
交大名義發表
;
材料科學與工程學系
;
National Chiao Tung University
A water-cooling centrifugal casting method was applied to cast the 7075 Al alloy to generate a much finer cast structure than that produced by conventional ingot casting methods. The effects of casting parameters, i.e., rotation speed, pouring temperature, water flow, and grain refiner, on casting structure were systematically studied so that the optimum casting condition and the solidification mechanism could be established. The typical cast structure along the thickness direction of a cast ring could be divided into four equiaxed zones, including the chill zone which is in contact with the mold wall. All zones have their characteristic grain size, morphology, and relative thickness, which are all dependent on the casting condition. The optimum casting condition yielding the finest structure available was found to be 3000 rpm, 650-degrees-C, and sufficient water cooling. A uniform portion occupying 90 pct of the whole thickness and having a grain size of 17 mum could be achieved under such a casting condition. When a grain refiner was added, the whole ring became further concentrated with grains of fine structure. A mechanism concerning the overall effects of rapid solidification, turbulent flow, and centrifugal force has been proposed for the present casting method and might explain the zone-structure formation and the effects of the casting parameters on microstructural features.
管管作品兩首
(1994-03-01)
管管
BENCHMARKING AND ANALYSIS OF SUPERSCALAR ARCHITECTURE
(1994-03-01)
SHIAU, YH
;
CHUNG, CP
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
Superscalar processing can improve the performance of a single CPU beyond that of traditional RISC machines by exploiting instruction-level parallelism. It is the objective of this study to design a superscalar system which will best exploit a given program's instruction-level parallelism. Three different architectural models, XPCB, XXPB, and X4P2, are used as vehicles in evaluating system performance and the degree of utilization of each individual functional unit. The XPCB model is used as a preliminary model to analyze the loading breakdowns of the various function types. It was found that the performance improvement of the XPCB model relative to a single-instruction stream model is only about 4.3 percent. In addition, the fixed-point operations are in great demand, and dominate the behavior as well as performance of the processor. Two enhanced models, the XXPB and the X4P2, are suggested to improve on the performance of the XPCB model by distributing fixed-point, and even floating-point operation loads among multiple functional units of the same type(s). Simulations show that the XXPB and X4P2 models can improve the performance of the sequential model by 50.8 and 61.6 percent, respectively.
管管作品兩首
(1994-03-01)
管管
管管作品兩首
(1994-03-01)
管管
AN OPTIMAL PARALLEL ALGORITHM FOR GENERATING PERMUTATIONS IN MINIMAL CHANGE ORDER
(1994-03-01)
TSAY, JC
;
LEE, WP
;
交大名義發表
;
工學院
;
National Chiao Tung University
Permutation generation is an important problem in combinatorial computing. In this paper we present an optimal parallel algorithm to generate all N! permutations of N objects. The algorithm is designed to be executed on a very simple computation model that is a linear array with N identical processors. Because of the simplicity and regularity of the processors, the model is very suitable for VLSI implementation. Another advantageous characteristic of this design is that it can generate all the permutations in minimal change order.
MONTE-CARLO SIMULATION FOR CORRELATED VARIABLES WITH MARGINAL DISTRIBUTIONS
(1994-03-01)
CHANG, CH
;
TUNG, YK
;
YANG, JC
;
土木工程學系
;
Department of Civil Engineering
As computation speed increases, Monte Carlo simulation is becoming a viable tool for engineering design and analysis. However, restrictions are often imposed on multivariate cases in which the involved stochastic parameters are correlated. In multivariate Monte Carlo simulation, a joint probability distribution is required that can only be derived for some limited cases. This paper proposes a practical multivariate Monte Carlo simulation that preserves the marginal distributions of random variables and their correlation structure without requiring the complete joint distribution. For illustration, the procedure is applied to the reliability analysis of a bridge pier against scouring.
BENCHMARKING AND ANALYSIS OF SUPERSCALAR ARCHITECTURE
(1994-03-01)
SHIAU, YH
;
CHUNG, CP
;
資訊科學與工程研究所
;
Institute of Computer Science and Engineering
Superscalar processing can improve the performance of a single CPU beyond that of traditional RISC machines by exploiting instruction-level parallelism. It is the objective of this study to design a superscalar system which will best exploit a given program's instruction-level parallelism. Three different architectural models, XPCB, XXPB, and X4P2, are used as vehicles in evaluating system performance and the degree of utilization of each individual functional unit. The XPCB model is used as a preliminary model to analyze the loading breakdowns of the various function types. It was found that the performance improvement of the XPCB model relative to a single-instruction stream model is only about 4.3 percent. In addition, the fixed-point operations are in great demand, and dominate the behavior as well as performance of the processor. Two enhanced models, the XXPB and the X4P2, are suggested to improve on the performance of the XPCB model by distributing fixed-point, and even floating-point operation loads among multiple functional units of the same type(s). Simulations show that the XXPB and X4P2 models can improve the performance of the sequential model by 50.8 and 61.6 percent, respectively.
AN OPTIMAL PARALLEL PERCEPTRON LEARNING ALGORITHM FOR A LARGE TRAINING SET
(1994-03-01)
HONG, TP
;
TSENG, SS
;
資訊工程學系
;
Department of Computer Science
In [2], a parallel perceptron learning algorithm on the single-channel broadcast communication model was proposed to speed up the learning of weights of perceptrons [3]. The results in [2] showed that given n training examples, the average speedup is 1.48*n0.91/log n by n processors. Here, we explain how the parallelization may be modified so that it is applicable to any number of processors. Both analytical and experimental results show that the average speedup can reach nearly O(r) by r processors if r is much less than n.
UNDERSTANDING MATHEMATICAL EXPRESSIONS USING PROCEDURE-ORIENTED TRANSFORMATION
(1994-03-01)
LEE, HJ
;
LEE, MC
;
交大名義發表
;
資訊工程學系
;
National Chiao Tung University
A system for understanding mathematical expressions is presented. The mathematical expressions scanned from a printed document are recognized and transformed into one-dimensional (1D) strings according to the format of a publication system. After separating all symbols in an input mathematical expression, 13 features are utilized to represent each symbol. In order to reduce the computational time, a coarse classification algorithm is applied to reduce the number of candidates. Then for each input symbol, the character with the highest similarity is selected as the candidate symbol. Since some of the symbols in an arithmetical expression may touch each other, a dynamic programming algorithm which uses structural features is adopted to identify correct characters from connected symbols. In the expression formation stage, a procedure-oriented method is proposed to translate the recognized symbols from a two-dimensional (2D) space into a 1D character string. A total of 105 mathematical expressions have been used as training data and 50 expressions as testing data. The experimental results have demonstrated the feasibility of the understanding system.
NEARLY NONINTERACTING DESIGN OF MULTIVARIABLE FEEDBACK-SYSTEMS
(1994-03-01)
CHENG, CC
;
TSAI, TP
;
WANG, TS
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, a practical approach is introduced for the design of multivariable feedback systems. At first, the cross-coupling in the plant is expressed in terms of the equivalent disturbance. The ''non-interacting'' formula is then established to remove the effects of the equivalent disturbance on the designing compensator. Ultimately, ''nearly non-interacting control'' is concerned from the viewpoints of engineering. A typical two-degree-of-freedom system structure is adopted to handle the conflict between the command-tracking performance and the disturbance-rejection requirement.
GAAS BIDIRECTIONAL BISTABILITY SWITCH USING DOUBLE TRIANGULAR BARRIER STRUCTURES
(1994-03-01)
YARN, KF
;
WANG, YH
;
CHANG, CY
;
電控工程研究所
;
Institute of Electrical and Control Engineering
We report on the experimental results of a new bidirectional bistability switching device using GaAs double triangular barrier structures prepared by molecular beam epitaxy. Bidirectional switching has been predicted experimentally in n+-n--delta(p+)-n--p+-n--delta(p+)-n--n+ structure. The significant S-shaped negative differential resistance characteristics are obtained due to the voltage-induced avalanche breakdown and potential barrier redistribution. A large on/off voltage ratio of approximately 6.5 is observed in either direction of two-state at room temperature. In addition, the device can be expected to operate as a three-terminal triggered triac.
管管作品三首
(1994-03-01)
管管