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排序方式: 共有276条查询结果,搜索用时 15 毫秒
271.
In this paper we propose various neighborhood search heuristics (VNS) for solving the location routing problem with multiple capacitated depots and one uncapacitated vehicle per depot. The objective is to find depot locations and to design least cost routes for vehicles. We integrate a variable neighborhood descent as the local search in the general variable neighborhood heuristic framework to solve this problem. We propose five neighborhood structures which are either of routing or location type and use them in both shaking and local search steps. The proposed three VNS methods are tested on benchmark instances and successfully compared with other two state-of-the-art heuristics. 相似文献
272.
Nanoporous titanium dioxide (TiO2) based conductometric sensors have been fabricated and their sensitivity to hydrogen (H2) gas has been investigated. A filtered cathodic vacuum arc (FCVA) system was used to deposit ultra-smooth Ti thin films on a transducer having patterned inter-digital gold electrodes (IDTs). Nanoporous TiO2 films were obtained by anodization of the titanium (Ti) thin films using a neutral 0.5% (wt) NH4F in ethylene glycol solution at 5 V for 1 h. After anodization, the films were annealed at 600 °C for 8 h to convert the remaining Ti into TiO2. The scanning electron microscopy (SEM) images revealed that the average diameters of the nanopores are in the range of 20 to 25 nm. The sensor was exposed to different concentrations of H2 in synthetic air at operating temperatures between 100 °C and 300 °C. The sensor responded with a highest sensitivity of 1.24 to 1% of H2 gas at 225 °C. 相似文献
273.
H. Sadek C.Y. Ching J. Cotton 《International Journal of Heat and Mass Transfer》2010,53(19-20):4141-4151
An experimental study was performed to determine the modes of heat transfer in horizontal tube side convective condensation under an applied DC high voltage. Experiments were performed with R134a in a horizontal, single-pass, counter-current heat exchanger. A 8 kV DC voltage was applied through a central rod electrode with the tube wall grounded for mass flux in the range 45–156 kg/m2 s. The average quality across the test section was 45%, which corresponds to an initially stratified flow with the liquid level below the central electrode. The high-voltage electric field results in an interfacial electric body force which extracts the liquid from the bottom stratum towards the vapour core. This results in a phase redistribution with a resultant increase in heat transfer. The increase in heat transfer can be attributed to a change of the heat transfer mode in the lower section of the tube from convective condensation to film condensation. 相似文献
274.
Bassem AssfourStefano Leoni Sergei YurchenkoGotthard Seifert 《International Journal of Hydrogen Energy》2011,36(10):6005-6013
A multiscale approach is used to investigate the hydrogen adsorption in nanoporous Zeolite Imidazolate Frameworks (ZIFs) on varying geometries and organic linkers. Ab initio calculations are performed at the MP2 level to obtain correct interaction energies between hydrogen molecules and the ZIF structures. Subsequently, classical grand canonical Monte-Carlo (GCMC) simulations are carried out to obtain the hydrogen uptake of ZIFs at different thermodynamic conditions of pressure and temperature. 相似文献
275.
Chaker Essid M. Bassem Ben Salah Abdelaziz Samet 《International Journal of Numerical Modelling》2016,29(4):763-772
In this paper, a new hybrid method formulation to resolve the mixed potential integral equation in an efficient and a fast approach, which is based on a simultaneous formulation in both spatial and spectral domains, is proposed. The entries of the method of moments matrix are then given by the sum of two integrals. The first one is expressed in the spatial domain. This part is analytically evaluated after a development in Taylor series of the exponential terms in the function to integrate. The integrals expressed in the spectral domain have a finite range, and they are calculated using numerical integration. Then the convergence problem is avoided in this approach. A good agreement between the simulated and measured results has been achieved. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
276.
Silicon - Electrochemical behavior of A 356 Al alloy and its composites reinforced by zirconia and prepared by vortex and squeeze casting was studied in acid rain using open circuit potential,... 相似文献