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971.
本文主要研究了顾客一般独立批到达、指数批服务、缓冲器容量有限的单个服务器的排队系统,本文首先使用补充变量和嵌入马氏链的方法,在部分拒绝和全部拒绝情形下,得到系统排队队长的稳态分布,进而得到相应的性能指标,如系统的平均排队长、平均等待时间、损失概率等.其次对等待时间进行了分析. 相似文献
972.
Based on a fictitious market model, a decentralized approach is presented for the workstation scheduling in a CNC workshop. A multi-agent framework is proposed, where job agents and resource agents act as buyers and sellers of resource in the virtual market. With cost and benefit calculation of these agent activities, which reflects the state of the production environment, various, and often conflicting goals and interests influencing the scheduling process in practice can be balanced through a unified instrument offered by the markets. The paper first introduces a heuristic procedure that makes scheduling reservations in a periodic manner. A multi-agent framework is then introduced, in which job agents and resource agents seek appropriate job–workstation matches through bidding in the construction of the above periodic “micro-schedules”. A pricing policy is proposed for the price-directed coordination of agent activities in this. Simulation results demonstrate the feasibility of the proposed approach and give some insights on the effects of some decision making parameters. Future work will be focused on the designing of some more sophisticated coordination mechanism and its deployment. 相似文献
973.
974.
设计计算了以Al为底层的多层Al-C-O的太阳吸收涂层。运用直流磁控溅射制备了这种Al-C-O/Al吸收涂层。理论计算与实验测量的结果基本一致。经真空中烘烤后,涂层的Al-C-O/Al太阳吸收率α≈0.92,室温热发射率ε≈0.04,具有优良的光谱选择性。由于使用单个溅射靶,简化了溅射系统,提高了靶溅射的利用率。
关键词: 相似文献
975.
A model ferromagnetic metal is used to calculate the spin-polarization which occurs during inelastic electron-metal scattering with the production of an electron-hole pair. The polarization is found to have contributions from unequal spin-flip as well as non-flip energy loss rates. Our results indicate an asymmetry of the order of a few percent with parameters roughly modelling iron. 相似文献
976.
In this paper, we compute the complete Einstein-Kähler metric with explicit formula for the Cartan-Hartogs domain of the fourth type in some cases. Under this metric the holomorphic sectional curvature is given, which intervenes between −2k and −1. This is the sharp estimate.
相似文献977.
Gang‐Yin Shi Li‐Ping Yang Cai‐Yuan Pan 《Journal of polymer science. Part A, Polymer chemistry》2008,46(19):6496-6508
Well‐defined hetero eight‐shaped copolymers composed of polystyrene (PS) and poly(ε‐caprolactone) (PCL) with controlled molecular weight and narrow molecular weight distribution were successfully synthesized by the combination of ring‐opening polymerization, ATRP, and “click” reaction. The synthetic procedure involves three steps: (1) preparation of a tetrafunctional PS and PCL star copolymer with two PS and two PCL arms using the tetrafunctional initiator bearing two hydroxyl groups and two bromo groups; (2) synthesis of tetrafunctional star copolymer, (α‐acetylene‐PCL)2(ω‐azido‐PS)2, by the transition of terminal hydroxyl and bromo groups to acetylene and azido groups through the reaction with 4‐propargyloxybutanedioyl chloride and NaN3 respectively; (3) intramolecular cyclization reaction to produce the hetero eight‐shaped copolymers using “click” chemistry under high dilution. The 1H NMR, FTIR, and gel permeation chromatography techniques were applied to characterize the chemical structures of the resulted intermediates and the target polymers. Their thermal behavior was investigated by DSC, and their crystallization behaviors of PCL were studied by polarized optical microscopy. The decrease in chain mobility of the eight‐shaped copolymers restricts the crystallization of PCL and the crystallization rate of PCL is slower in comparison with their corresponding star precursors. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6496–6508, 2008 相似文献
978.
Vacuum-prepared multi-layer Cu films have been studied by x-ray diffraction to detect the averaged dislocation density and distribution. There are very few stacking faults and a very small degree of texture in the films. 相似文献
979.
Keiji Yamamoto Kiyoshi Ikeda Leong Kwai Yin 《Journal of organometallic chemistry》1989,370(1-3):319-332
Enantioselective, homogeneous hydrogenation of 3-phenyl-3-butenoic acid (1) has extensively been examined in the presence of the rhodium(I)/4,5-bis[(diphenylphosphino)methyl]-2,2-dimethyldioxolane (DIOP) catalyst systems. Optimization of the reaction conditions was undertaken mainly by controlling effects of added tertiary amines as well as solvent polarities on the enantio-selectivity of the product. The best asymmetric yield (85.1% e.e.) was attained when the hydrogenation was carried out in the presence of triethylamine (5 mol%) in 75% aqueous methanol using a neutral rhodium-DIOP catalyst. 相似文献
980.