Browsing by Author "Ho, YC"

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An ordinal optimization theory-based algorithm for solving the optimal power flow problem with discrete control variables
(2004-02-01)
Lin, SY
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Ho, YC
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Lin, CH
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電控工程研究所
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Institute of Electrical and Control Engineering
The optimal power flow (OPF) problem with discrete control variables is an NP-hard problem in its exact formulation. To cope with the immense computational-difficulty of this problem, we propose an ordinal optimization theory-based algorithm to solve for a good enough solution with high probability. Aiming for hard optimization problems, the ordinal optimization theory, in contrast to heuristic methods, guarantee to provide a top n% solution among all with probability more than 0.95. The approach of our ordinal optimization theory-based algorithm consists of three stages. First, select heuristically a large set of candidate solutions. Then, use a simplified model to select a subset of most promising solutions. Finally, evaluate the candidate promising-solutions of the reduced subset using the exact model. We have demonstrated the computational efficiency of our algorithm and the quality of the obtained solution by comparing with the competing methods and the conventional approach through simulations.
Chemistry of Ti(OiPr)Cl-3 with chloride and oxygen-containing ligands: The roles of alkoxide and solvents in the six-coordinate titanium complexes
(1996-03-27)
Gau, HM
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Lee, CS
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Lin, CC
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Jiang, MK
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Ho, YC
Ti((OPr)-Pr-i)Cl-3 reacts easily with various ligands to form a series of six-coordinate complexes, [Ti((OPr)-Pr-i)Cl-5](2-)(HAm+)(2) (Am = NEt(3) (7a) or NC5H5 (7b)), Ti((OPr)-Pr-i)Cl(3)L(2) (L = THF (8) or PhCHO (9)), Ti((OPr)-Pr-i)-Cl-3(PhCHO)(Et(2)O) (10), and [Ti((OPr)-Pr-i)Cl-2(mu-Cl)(PhC(O)OMe)](2) (11). Upon dissolution of 7a in THF, 8 was obtained. When 1 mol equiv of HNEt(3)Cl was added to 8, [Ti((OPr)-Pr-i)Cl-4(THF)](-)(HNEt(3))+ (12) was obtained. With the addition of another 1 mol equiv of HNEt(3)Cl, 12 was converted to 7a. One THF in 8 can be removed in vacuo to give the chloride-bridged dimer [Ti((OPr)-Pr-i)Cl-2(mu-Cl)(THF)](2) (13) which can be converted back to 8 by dissolving in THF. 13 was found to react with 2 mol equiv of HNEt(3)Cl or PhCHO to give 12 and Ti((OPr)-Pr-i)Cl-3(PhCHO)(THF) (14), respectively. The molecular structures of 7b, 8, and 10-13 show short Ti-(OPr)-Pr-i distances, and the relative bonding order of (OPr)-O---Pr-i > Cl-, THF > Et(2)O > PhCHO > mu-Cl- > RC(O)OMe is discussed based on the solid state structures. This bonding sequence is very useful for the prediction of the geometry for six-coordinate complexes of early transition metals with the following principle: The strongest ligand prefers a trans position to the weakest ligand, and the second strongest ligand favors a trans position to the second weakest ligand in the complex. Kinetically, the trans position to the isopropoxide is rather labile for substitution, and the lability of the trans ligand ensures the effectiveness of titanium alkoxides for subsequent reactions or as catalysts in many asymmetric organic syntheses.
Closure to "Passive earth pressure with critical state concept" by Yung-Show Fang, Ying-Chieh Ho, and Tsang-Jiang Chen
(2003-10-01)
Fang, YS
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Ho, YC
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Chen, TJ
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土木工程學系
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Department of Civil Engineering
Fully static processor optimal assignment of data-flow graphs
(1997-05-01)
Ho, YC
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Tsay, JC
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資訊工程學系
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Department of Computer Science
The data-flow graph (DFG) is an important graph-theoretic model for multiprocessor implementation of real-time digital signal processing (DSP) algorithms. Given a time schedule for a DFG,, we consider the problem of the processor-optimal assignment for a fully static schedule. Previously, the solution of this problem was found by solving an integer programming problem. In this letter, we propose a linear programming approach to solving the problem.
Passive earth pressure with critical state concept
(2002-08-01)
Fang, YS
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Ho, YC
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Chen, TJ
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土木工程學系
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Department of Civil Engineering
This paper presents experimental data of earth pressure acting against a vertical rigid wall, which moved toward a mass of dry sand. The backfill had been placed in lifts to achieve relative densities of 38, 63, and 80%. The instrumented retaining-wall facility at National Chiao Tung University in Taiwan was used to investigate the effects of soil density on the development of earth pressure. Based on the experimental data, it has been found that the Coulomb and Terzaghi solutions calculated with the peak internal friction angle significantly overestimated the ultimate passive thrust for the retaining wall filled with dense sand. As the wall movement S exceeded 12% of the wall height H, the passive earth thrust would reach a constant value, regardless of the initial density of backfill. Under such a large wall movement, soils along the rupture surface had reached the critical state, and the shearing strength on the surface could be properly represented with the residual internal-friction angle. The ultimate passive earth pressure was successfully estimated by adopting the critical state concept to either Terzaghi or Coulomb theory.
Universal alignment probability revisited
(2002-05-01)
Lin, SY
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Ho, YC
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電控工程研究所
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Institute of Electrical and Control Engineering
In this note, we quantify and validate the representativeness of the uniformly sampled set N for the search space Theta and the use of universal alignment probability (UAP) curves.