Browsing by Author "Chou, JB"

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Improved solutions for the Chinese postman problem on mixed networks
(1999-07-01)
Pearn, WL
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Chou, JB
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工業工程與管理學系
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Department of Industrial Engineering and Management
The Chinese postman problem (CPP) is that of finding the shortest postman tour covering all the roads in the network. The CPP is polynomial-time solvable on totally directed or undirected networks, but is NP-complete on mixed networks (MCPP). Several heuristic solution procedures including Mixed-1, Mixed-2 Modified Mixed-1, and Modified Mixed-2 algorithms, have been proposed to solve the problem approximately. In this paper, we briefly review these four existing algorithms, then propose two improvement procedures to improve the solutions. The proposed procedures are tested and compared with the four existing algorithms. The results show that the proposed procedures significantly improve the existing solutions. (C) 1999 Elsevier Science Ltd. All rights reserved.
Isomers of GeNO and Ge(NO)(2): Production and infrared absorption of GeNO and ONGeNO in solid Ar
(2005-08-01)
Chou, JB
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Bahou, M
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Lee, YP
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Rayner, D
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Simard, B
Crystalline germanium was ablated with light at 532 nm from a frequency-doubled neodymium: yttrium aluminum garnet laser, and the resultant plume reacted with NO before deposition onto a substrate at 13 K. Lines in group A at 1543.8 and 3059.7 cm(-1) that become enhanced at the initial stage of irradiation at 308 or 193 nm and also after annealing are attributed to nu(1) and 2 nu(1) of GeNO. Lines in group B at 1645.5 and 1482.8 cm(-1) that become diminished after further irradiation of the matrix at 308 or 193 nm but become enhanced after annealing are attributed to symmetric NO stretch (nu(1)) and antisymmetric NO stretch (nu(7)) of ONGeNO. The assignments were derived based on wave numbers and isotopic ratios observed in the experiments with N-15- and O-18-isotopic substitutions and predicted with quantum-chemical calculations. Quantum-chemical calculations with density-functional theories (B3LYP and BLYP/aug-cc-pVTZ) predict four stable isomers of GeNO, six isomers of Ge2NO, and four isomers of Ge(NO)(2), with linear GeNO, cyc-GeNGeO, and cyc-GeONNO having the least energies, respectively. The formation mechanisms of GeNO and ONGeNO are discussed. In addition, a weak line at 1417.0 cm(-1) and two additional lines associated with minor matrix sites at 1423.0 and 1420.3 cm(-1) are assigned to GeNO-. (C) 2005 American Institute of Physics.