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151.
本文从纵向上对20世纪以来的古代儒家文艺思想的研究现状作了回顾,从横向上剖析了新时期以来的几个主要研究方面,并就研究现状作了相应的学术反思. 相似文献
152.
153.
We consider the problem of scheduling n independent jobs on m unrelated parallel machines with sequence-dependent setup times and availability dates for the machines and release dates for the jobs to minimize a regular additive cost function. In this work, we develop a new branch-and-price optimization algorithm for the solution of this general class of parallel machines scheduling problems. A new column generation accelerating method, termed “primal box”, and a specific branching variable selection rule that significantly reduces the number of explored nodes are proposed. The computational results show that the approach solves problems of large size to optimality within reasonable computational time. 相似文献
154.
When the processing times of jobs are controllable, selected processing times affect both the manufacturing cost and the scheduling performance. A well known example for such a case that this paper specifically deals with is the turning operation on a CNC machine. Manufacturing cost of a turning operation is a nonlinear convex function of its processing time. In this paper, we deal with making optimal machine-job assignments and processing time decisions so as to minimize total manufacturing cost while the makespan being upper bounded by a known value, denoted as ?-constraint approach for a bicriteria problem. We then give optimality properties for the resulting single criterion problem. We provide alternative methods to compute cost lower bounds for partial schedules, which are used in developing an exact (branch and bound) algorithm. For the cases where the exact algorithm is not efficient in terms of computation time, we present a recovering beam search algorithm equipped with an improvement search procedure. In order to find improving search directions, the improvement search algorithm uses the proposed cost bounding properties. Computational results show that our lower bounding methods in branch and bound algorithm achieve a significant reduction in the search tree size that we need to traverse. Also, our recovering beam search and improvement search heuristics achieve solutions within 1% of the optimum on the average while they spent much less computational effort than the exact algorithm. 相似文献
155.
覃主元 《广西民族大学学报》2004,(5)
近代梧州商业特别发达 ,是全省商业之中心 ,曾一度控制着全省的经济命脉 ,是广西经济的重心。然而今天 ,对外贸易曾居广西之冠的梧州市 ,则相对日见落后。梧州要重振商埠雄风 ,应充分利用其优越的区位优势 ,大力发展商贸经济 ,把梧州建成广西的商贸中心和西南最大的商贸城 相似文献
156.
We investigate the relation between the underlying dynamics of randomly evolv ing systems and the extrema statistics for such systems. Independent processes, Fokker-Planck processes and Lévy processes are considered. 相似文献
157.
G. Wolschin 《Annalen der Physik》1994,506(4):276-282
To account for the non-equilibrium character of quark-gluon plasma formation in relativistic heavy-ion collisions, it is proposed to use the product of energy density ? and interaction time τint (rather than ?) as the critical quantity for plasma formation. In a geometrical model, τ is approximated by the transit time, and ? by the maximum energy density calculated in the center-of-mass frame. For central collisions, an analytical expression for ?·τ is given. As an example, the systems 16O + 16O and 208Pb + 208Pb are investigated as functions of c.m. energy, and their respective suitability for plasma formation is discussed. 相似文献
158.
优化分级T-S模糊控制动态估计纯电动汽车电池健康状态 总被引:1,自引:1,他引:0
针对纯电动汽车动力电池健康状态(state of health,SOH)预测中非线性影响因素多、算法繁杂、难以在单片机开发平台中实现等难点,首先利用累计充电循环次数计量法得到使用循环次数,将SOH与使用循环次数、内阻变化量、电压降值的相关非线性关系转换成离散的二维数据表,依据使用条件,采用二分查表法获得不同估计方法下SOH值;再将使用循环次数、电压降值和内阻变化量作为输入量,以相应SOH的权重作为输出,利用T-S模糊控制建立SOH动态预测模型,根据权重和边界条件计算得到SOH.仿真结果表明,所提方法最大预测误差4.3%,响应时间55 ms内,预测效果比现有方法显著提高. 相似文献
159.
Chemisorption of 1,1-dichloroethene (Cl2CCH2) to a Si(1 1 1)-7 × 7 surface was studied by means of X-ray photoelectron spectroscopy using synchrotron radiation, recording chlorine 2p and carbon 1s spectra. For carbon 1s, spectral assignment of the chemisorbed species is based on quantum chemical calculations of chemical shifts in model compounds.The results confirm the identity of covalently bonded 1-chlorovinyl (-CClCH2) and vinylidene (CCH2) adspecies. Upon chemisorption at room temperature it was found that about one-third of the molecules break one C-Cl bond while about two-thirds of the adsorbates break two C-Cl bonds. We do not, however, find evidence for isomerization of CCH2 to di-bonded vinylene (-CHCH-). 相似文献
160.
何军 《应用数学和力学(英文版)》2007,28(11):148-1494
An analytical moment-based method for calculating structural first failure times under non-Gaussian stochastic behavior is proposed.In the method,a power series that constants can be obtained from response moments (skewness,kurtosis,etc.) is used firstly to map a non-Gaussian structural response into a standard Gaussian process,then mean up-crossing rates,mean clump size and the initial passage probability of a critical barrier level by the original structural response are estimated,and finally,the formula for calculating first failure times is established on the assumption that corrected up-crossing rates are independent.An analysis of a nonlinear single-degree-of-freedom dynamical system excited by a Gaussian model of load not only demonstrates the usage of the proposed method but also shows the accuracy and efficiency of the proposed method by comparisons between the present method and other methods such as Monte Carlo simulation and the traditional Ganssian model. 相似文献