Browsing by Author "Chen, YW"

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Fuzzy multi-objective reconstruction plan for post-earthquake road-network by genetic algorithm
(2000)
Tzeng, GH
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Chen, YW
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Lin, CY
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運輸與物流管理系註：原交通所+運管所
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資訊管理與財務金融系註：原資管所+財金所
According to the seismic experience of Japan and America, earthquakes have often caused damage to the road-networks, which are important for maintaining the quality of life and the daily transit after a disaster. Taiwan and Japan are both located in the Pacific earthquake region, which is very active and unstable. The Taiwanese people will suffer seriously after a large-scale earthquake because the population and road-network are both highly concentrated nowadays. If the necessary reconstruction strategies to cope with quakes are not available, mass travelers can't be efficiently conducted via the post-earthquake road-network. Thus, the convenience of transit after earthquake would be seriously hampered. To aid the reconstruction decision for post-earthquake road-networks, we intend to establish a fuzzy multi-objective model, which is an integration of work scheduling and task assignment for many work-troops. Multiobjective optimization is applied because of the following reasons: first, we do want to minimize the travel-time of travelers during reconstruction; secondly, we intend to minimize total time needed for reconstruction; furthermore, we also expect that each available and homogeneous work-troop on duty will share almost the same work-load during reconstruction. Since the aspiration level of the aforementioned goals are vague, a fuzzy multi-objective approach is used. The algorithm of this combinatorial optimization problem based on a two-step genetic algorithm is then developed and employed to reduce the computation complexity of such a problem. Study results show that a satisfying solution of this problem can be efficiently derived by thirty generations of our modified genetic algorithm- this solution not only instructs the reconstruction order for each damage point in road-network, but also assign the appropriate reconstruction work to relevant work-troops. Thus, for reasons of computational efficiency and practical applicability in this study, we do strongly suggest this research can't only be a basis for seismic simulation but can also be the reference of pre-quake exercises for relevant authorities.
Systematic tuning of the luminescent properties of self-activated ZnGa2O4 phosphors by Cd ion substitution
(2000-02-15)
Chen, TM
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Chen, YW
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應用化學系
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Department of Applied Chemistry
The effect of host compositions on the luminescent properties of spinel-type ZnGa2O4 phosphors was investigated by systematic substitution of Cd2+ for Zn2+ in the host lattice. A continuous solid solution with the composition (Zn1-xCdx)Ga2O4 (0 less than or equal to x less than or equal to 1.0) was synthesized at 950 degrees C as self-activated phosphors, as indicated by X-ray diffraction (XRD) analysis. With increasing substitution of Cd2+ the emission and excitation wavelengths (lambda(cm) and lambda(exc)) of self-activated (Zn1-xCdx)Ga2O4 were observed to exhibit a red shift, as indicated by photoluminescence spectral analysis. Similar results were also confirmed by cathodoluminescence data. Our observations are attributed to the systematic narrowing of the energy gap of the host attributed to expanding lattice dimensions induced by Cd2+ substitution. A CIE: chromaticity diagram manifests the effect of Cd2+ doping on variation of hue for the (Zn1-xCdx)Ga2O4 gallate phosphors. (C) 2000 Academic Press.
The optimal location of airport fire stations: A fuzzy multi-objective programming and revised genetic algorithm approach
(1999)
Tzeng, GH
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Chen, YW
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運輸與物流管理系註：原交通所+運管所
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Department of Transportation and Logistics Management
As the global aviation business expands rapidly, issues of aviation safety become correspondingly important. In turn, aviation safety should be more emphasized. The crashes of China Airlines planes at Nagoya (Japan) international airport in 1994, and near Taipei's international airport in 1998, caused airport authorities around the world to pay closer attention to rescue and fire-protection plans at their airports. Our research reveals that the location and number of fire stations at an international airport is an important factor in its fire protection capability. However, if the sites of the fire stations are not appropriately planned and located, fire engines and crews cannot arrive at the accident area in a timely manner. Similarly, if the number of fire stations at an airport is not sufficient, fires caused by aircraft accidents may take longer to be extinguished, resulting in more injuries and fatalities. Therefore, a location model based on a fuzzy multi-objective approach is proposed in this paper. This model can help in determining the optimal number and sites of fire stations at an international airport, and can also assist the relevant authorities in drawing up optimal locations for fire stations. Finally, because of the combinatorial complexity of our model, a genetic algorithm (GA) is employed and compared with the enumeration method. The study results show that our revised CA is comparatively effective in resolution and that our model can be applied to the optimal location of other emergency facilities.
Using fuzzy integral for evaluating subjectively perceived travel costs in a traffic assignment model
(2001-05-01)
Chen, YW
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Tzeng, GH
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管理學院
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College of Management
A good traffic assignment model can be a powerful tool to describe the characteristics of traffic behavior in a road network. The traffic assignment results often play an important role in transportation planning, e.g., an optimal and economical network design, Many traditional traffic assignment models rely heavily on the travel cost function established by Wardrop's principles; however, the Wardrop's travel cost function has been proven to be weak for explaining the uncertainty and interactivity of traffic among links. This study tries to construct a traffic assignment model that is different from Wardrop's in many aspects. First, it considers the cross-effect among the links, Second, a fuzzy travel cost function is established based on the possibility concept instead of precise calculation of traffic volumes. Third, the techniques of fuzzy measure and fuzzy integral are applied to calculate the subjectively perceived travel costs during traffic assignment. Furthermore, in order to validate our model, a detailed network with 22 nodes and 36 links is used to illustrate it. Study results show that our model explains more interactivity and uncertainty of traffic among links when compared with the traditional model of Wardrop's. (C) 2001 Elsevier Science B.V. Al rights reserved.