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Dengiz B. Altiparmak F. Smith A.E. 《Evolutionary Computation, IEEE Transactions on》1997,1(3):179-188
This paper presents a genetic algorithm (GA) with specialized encoding, initialization, and local search operators to optimize the design of communication network topologies. This NP-hard problem is often highly constrained so that random initialization and standard genetic operators usually generate infeasible networks. Another complication is that the fitness function involves calculating the all-terminal reliability of the network, which is a computationally expensive calculation. Therefore, it is imperative that the search balances the need to thoroughly explore the boundary between feasible and infeasible networks, along with calculating fitness on only the most promising candidate networks. The algorithm results are compared to optimum results found by branch and bound and also to GA results without local search operators on a suite of 79 test problems. This strategy of employing bounds, simple heuristic checks, and problem-specific repair and local search operators can be used on other highly constrained combinatorial applications where numerous fitness calculations are prohibitive 相似文献
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Conducting carbon/polymer composites as a catalyst support for proton exchange membrane fuel cells 下载免费PDF全文
Carbon/poly(3,4‐ethylene dioxythiophene) (C/PEDOT) composites are synthesized by in situ chemical oxidative polymerization of EDOT monomer on carbon black in order to decrease carbon corrosion that occurred in carbon‐supported catalysts used in proton exchange membrane fuel cell. The effects of different dopants including polystyrene sulfonic acid, p‐toluenesulfonic acid and camphorsulfonic acid with the addition of ethylene glycol or dimethyl sulfoxide on the properties of the composites are investigated. The synthesized composites are characterized by X‐ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, surface area analysis and scanning electron microscope. Electrical conductivity is determined by using the four‐point probe technique. Electrochemical oxidation characteristics of the synthesized C/PEDOT composites are investigated by cyclic voltammetry by applying 1.2 V for 24 h. The composite prepared at 25 °C with p‐toluenesulfonic acid and ethylene glycol shows the best carbon corrosion resistance. Platinum‐supported catalyst by using this composite was prepared using microwave irradiation technique, and it was seen that the prepared catalyst did not significantly lose its hydrogen oxidation and oxygen reduction reaction activities after electrochemical oxidation. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Vehicle routing problem (VRP) is an important and well-known combinatorial optimization problem encountered in many transport logistics and distribution systems. The VRP has several variants depending on tasks performed and on some restrictions, such as time windows, multiple vehicles, backhauls, simultaneous delivery and pick-up, etc. In this paper, we consider vehicle routing problem with simultaneous pickup and delivery (VRPSPD). The VRPSPD deals with optimally integrating goods distribution and collection when there are no precedence restrictions on the order in which the operations must be performed. Since the VRPSPD is an NP-hard problem, we present a heuristic solution approach based on particle swarm optimization (PSO) in which a local search is performed by variable neighborhood descent algorithm (VND). Moreover, it implements an annealing-like strategy to preserve the swarm diversity. The effectiveness of the proposed PSO is investigated by an experiment conducted on benchmark problem instances available in the literature. The computational results indicate that the proposed algorithm competes with the heuristic approaches in the literature and improves several best known solutions. 相似文献
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In this paper, we consider the eigenvalue problems for fourth order integral boundary value problems on time scales for an increasing homeomorphism and homomorphism with sign changing nonlinearities. By using a fixed point index theorem, we give the existence of eigenvalue intervals in which there exist one symmetric positive solution to the problem. An example is also given to demonstrate the main results. 相似文献
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Evaluation of ISSR markers for genetic diversity analysis in Anatolian water buffaloes 总被引:1,自引:0,他引:1
Aytekin I Ozdil F Zulkadir U Boztepe S Sariyel V 《Journal of the science of food and agriculture》2011,91(11):1957-1962
BACKGROUND: The utilisation of molecular markers has increased in molecular research recently. Inter‐simple sequence repeat (ISSR) markers allow the analysis of genomes without preliminary sequence information, since random primers are used. The purpose of the present study was to evaluate ISSR markers for assessing the genetic diversity of indigenous Anatolian Water Buffaloes reared in Afyon, Konya and Sivas provinces of Turkey, with a view to conservation of the gene resources. RESULTS: The 11 ISSR primers chosen for the analysis revealed a total of 110 bands, of which 76 (69.09%) were polymorphic. Also, genetic similarity, polymorphic information content (PIC), resolving power (Rp) and mean resolving power (Rp ), heterozygosity (H) and Shannon index (I) were calculated as 0.9479–0.9562, 0.35 ± 0.20, 2.73, 0.27, 0.18 ± 0.07 and 0.28 ± 0.11, respectively. CONCLUSION: The ISSR markers were found to be promising for assessing the genetic diversity in buffalo populations. Potential genetic parameters such as PIC, Rp, Rp , H and I were effectively used in this study. Copyright © 2011 Society of Chemical Industry 相似文献
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Clean Technologies and Environmental Policy - Many countries, especially in arid and semiarid regions, suffer from water scarcity because of the decline in the existing freshwater reserves by... 相似文献
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Emrullah Karakaya Fulya Bagci Sultan Can Asim Egemen Yilmaz Baris Akaoglu 《国际射频与微波计算机辅助工程杂志》2019,29(1)
A four‐band metamaterial harvester for harvesting 0.9 GHz, 1.8 GHz, 2.6 GHz, and 5.8 GHz signals is proposed by a dual‐layer structure. 0.9 GHz and 1.8 GHz bands are harvested by the resistors in front layer, whereas harvesting of 2.6 GHz is achieved by the resistors in second layer. All resistors in front and back layer contribute to harvesting at 5.8 GHz. Numerical calculations are verified by two different full‐wave electromagnetic solvers based on finite‐integration and finite‐element techniques. Power dissipation ratios at 0.9 GHz, 1.8 GHz, 2.6 GHz and 5.8 GHz frequencies concentrated at the resistors are found as 82.3%, 82.8%, 74.6%, and 83.6%, respectively, by the finite‐integration‐based solver. Besides, the finite‐element method‐based solver results in harvesting efficiencies of 79.6%, 93.4%, 73.7%, and 93.8%. The efficiency of the harvester is investigated for different oblique incidences. The proposed metamaterial harvester can be a good candidate for multi‐band absorption and harvesting applications. 相似文献
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Effect of potassium ion on the stability and release rate of hydrogen peroxide encapsulated in silica hydrogels 下载免费PDF全文
Ezgi Melis Dogan Fulya Sudur Zalluhoglu Nese Orbey 《American Institute of Chemical Engineers》2017,63(2):409-417
Hydrogen peroxide (H2O2) is encapsulated in silica hydrogels using sol‐gel method and the effects of the K+ : Na+ ion ratio on gelation time, hydrogel structure, stability, and release rate of H2O2 were investigated. As the amount of K+ ions increased relative to the amount of Na+ ions at the same pH, the gel structure became less compact and the pore diameter increased. Hydrogen peroxide retention values up to 90 and 80% were observed at the end of 7 and 20 days, respectively, in the presence of K+ ions at low pH values when the initial H2O2 concentration was 19.9 wt %. Release rate of hydrogen peroxide decreased with decreasing pH for the two K+ : Na+ ion ratios studied. This work presents an environmentally friendly, low cost, and easy to scale up method to increase the stability of high initial concentrations of H2O2 at room temperature and customize the release rate. © 2016 American Institute of Chemical Engineers AIChE J, 63: 409–417, 2017 相似文献
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The fate of oxytetracycline in two‐phase and single‐phase anaerobic cattle manure digesters and its effects on microbial communities 下载免费PDF全文