Browsing by Author "Tsai, JF"

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A distributed global optimization method for packing problems
(2003-04-01)
Li, HL
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Tsai, JF
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Hu, NZ
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資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
Packing optimization problems aim to seek the best way of placing a given set of rectangular cartons within a minimum volume rectangular container. Currently, packing optimization methods either have difficulty in finding a globally optimal solution or are computationally inefficient, because models involve too many 0-1 variables and because use of just a single computer. This study proposes a distributed computation method for solving a packing problem by a set of personal computers via the Internet. First, the traditional packing optimization model is converted into an equivalent model containing many fewer 0-1 variables. Then the model is decomposed into several sub-problems by dividing the objective value into many intervals. Each of these sub-problems is a linearized logarithmic program expressed as a linear mixed 0-1 problem. The whole problem is solvable and reaches a globally optimal solution. The numerical examples demonstrate that the proposed method can obtain the global optimum of a packing problem effectively.
A fast algorithm for assortment optimization problems
(2001-10-01)
Li, HL
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Tsai, JF
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資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
Assortment optimization problems intend to seek the best way of placing a given set of rectangles within a minimum-area rectangle. Such problems are often formulated as a quadratic mixed 0-1 program. Many current methods for assortment problems are either unable to find an optimal solution or being computationally inefficient for reaching an optimal solution. This paper proposes a new method which finds the optimum of assortment problem by solving few linear mixed 0-1 programs. Numerical examples show that the proposed method is more computationally efficient than current methods.
A global optimization method for packing problems
(2006-09-01)
Tsai, JF
;
Li, HL
;
資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
The objective of packing problems is to determine an optimal way of placing a given set of three-dimensional (3D) rectangular cartons within a minimum volume 3D rectangular container. Current packing optimization methods either use too many extra 0-1 variables or find it difficult to obtain a globally optimal solution. This study proposes an efficient method for finding the global optimum of packing problems. First the traditional packing optimization problem is converted into an equivalent program containing many fewer 0-1 variables than contained in current methods. Then the global optimum of the converted program is found by utilizing piecewise linearization techniques. The numerical examples demonstrate that the proposed method is capable of finding the global optimum of a packing problem.
A preliminary report on the Phase-I ATSC field test results in Taiwan
(2000)
Tsai, JF
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Lin, CC
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Hang, HM
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Tarng, JH
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Yu, HC
In May 1998, Taiwan formally adopted the ATSC Digital Television (DTV) as its local digital terrestrial broadcasting standard. In order to define the DTV service area and specify the transmission parameters, we like to know the characteristics of the DTV signal over the local irregular terrain, the impact of interference, and the relationship between the signal power and video quality. me measured the DTV signal and compared the DTV and the NTSC service availability. We selected 100 test sites in Taipei city and its vicinity including three types of environment: urban, suburban and rural areas. In general, the DTV system has a clear advantage over the NTSC system in reception quality.
Approximately global optimization for assortment problems using piecewise linearization techniques
(2002-08-01)
Li, HL
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Chang, CT
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Tsai, JF
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資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
Recently, Li and Chang proposed an approximate model for assortment problems. Although their model is quite promising to find approximately global solution, too many 0-1 variables are required in their solution process. This paper proposes another way for solving the same problem. The proposed method uses iteratively a technique of piecewise linearization of the quadratic objective function. Numerical examples demonstrate that the proposed method is computationally more efficient than the Li and Chang method. (C) 2002 Elsevier Science B.V. All rights reserved.
Global optimization for signomial discrete programming problems in engineering design
(2002-12-01)
Tsai, JF
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Li, HL
;
Hu, NZ
;
資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
This paper proposes a novel method to solve signomial discrete programming (SDP) problems frequently occurring in engineering design. Various signomial terms are first convexified following different strategies. The! original SDP program is then converted into a convex integer program solvable by commercialized packages to obtain globally optimal solutions. Compared with current SDP methods, the proposed method is guaranteed to converge to a global optimum, is computationally more efficient, and is capable of treating zero boundary problems. Numerical examples are presented to demonstrate the usefulness of the proposed method in engineering design.
Technical note - On optimization approach for multidisk vertical allocation problems
(2005-09-16)
Tsai, JF
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Li, HL
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資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
Multidisk vertical allocation (MDVA) problems intend to find an allocation of relations to disks such that the expected query cost is minimized. Recently, Chang [European Journal of Operational Research 143 (2002) 210] modified Rotem et al.'s [IEEE Transactions on Knowledge and Data Engineering 5 (1993) 882] method for solving an MDVA problem using a smaller number of binary variables. Chang's method however is unable to treat MDVA problems with possible replication of relations. This paper proposes another method to solve MDVA problems, which is more effective than Rotem et al.'s and is able to treat replication problems insolvable by Chang's method. (c) 2004 Elsevier B.V. All rights reserved.
Treating free variables in generalized geometric global optimization programs
(2005-09-01)
Li, HL
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Tsai, JF
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資訊管理與財務金融系註：原資管所+財金所
;
Department of Information Management and Finance
Generalized geometric programming (GGP) problems occur frequently in engineering design and management. Recently, some exponential-based decomposition methods [Maranas and Floudas, 1997,Computers and Chemical Engineering 21(4), 351-370; Floudas et al., 1999 , Handbook of Test Problems in Local and Global Optimization, Kluwer Academic Publishers, Boston, pp. 5-105; Floudas, 2000 Deterministic Global Optimizaion: Theory, Methods and Application, Kluwer Academic Publishers, Boston, pp. 257-306] have been developed for GGP problems. These methods can only handle problems with positive variables, and are incapable of solving more general GGP problems. This study proposes a technique for treating free (i.e., positive, zero or negative) variables in GGP problems. Computationally effective convexification rules are also provided for signomial terms with three variables.