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121.
局域网传输系统可用性分析 总被引:2,自引:0,他引:2
采用可用性概念 ,分析局域网络系统的工作情况 ,对系统的平均故障间隔时间、中断率等参数进行评估 ,为工程设计和系统维护提供参考依据 相似文献
122.
Parallel machine scheduling with batch deliveries to minimize total flow time and delivery cost
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Motivated by the flow of products in the iron and steel industry, we study an identical and parallel machine scheduling problem with batch deliveries, where jobs finished on the parallel machines are delivered to customers in batches. Each delivery batch has a capacity and incurs a cost. The objective is to find a coordinated production and delivery schedule that minimizes the total flow time of jobs plus the total delivery cost. This problem is an extension of the problem considered by Hall and Potts, Ann Oper Res 135 (2005) 41–64, who studied a two‐machine problem with an unbounded number of transporters and unbounded delivery capacity. We first provide a dynamic programming algorithm to solve a special case with a given job assignment to the machines. A heuristic algorithm is then presented for the general problem, and its worst‐case performance ratio is analyzed. The computational results show that the heuristic algorithm can generate near‐optimal solutions. Finally, we offer a fully polynomial‐time approximation scheme for a fixed number of machines. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 492–502, 2016 相似文献
123.
Bayesian models for multiattribute acceptance sampling have been developed under the assumption that sampling inspection is carried to completion. A Bayesian multiattribute model for stepwise sampling inspection is proposed, whereby sampling inspection is terminated as soon as the disposition of the inspection lot is determined. An iterative solution procedure is developed for obtaining optimal or near-optimal multiattribute acceptance sampling plans under stepwise sampling inspection. The effect of stepwise sampling inspection on the characteristics of an optimal sampling plan is investigated. It is shown that stepwise sampling inspection achieves a sampling plan with lower total expected cost than complete sampling inspection. In addition, it is shown that the sequence of attributes in a stepwise sampling inspection substantially affects the sampling plan and resultant expected cost. The proposed methodology is used to evaluate various heuristics which may be used to determine the sequence of attributes in a stepwise inspection procedure. 相似文献
124.
唐志龙 《军队政工理论研究》2001,2(2):32-34
在思想政治工作实践中 ,作为重要的非理性思维因素在工作主体的思维方式中是大量存在的 ,并且可以“配合”理性思维 ,促进思想政治工作的有效运行。本文分析了形象思维在工作主体思维方式中的地位 ,阐述了在思想政治工作中形象思维的过程、特征及其积极意义与作用 相似文献
125.
In urban rail transit systems of large cities, the headway and following distance of successive trains have been compressed as much as possible to enhance the corridor capacity to satisfy extremely high passenger demand during peak hours. To prevent train collisions and ensure the safety of trains, a safe following distance of trains must be maintained. However, this requirement is subject to a series of complex factors, such as the uncertain train braking performance, train communication delay, and driver reaction time. In this paper, we propose a unified mathematical framework to analyze the safety‐oriented reliability of metro train timetables with different corridor capacities, that is, the train traffic density, and determine the most reliable train timetable for metro lines in an uncertain environment. By employing a space‐time network representation in the formulations, the reliability‐based train timetabling problem is formulated as a nonlinear stochastic programming model, in which we use 0‐1 variables to denote the time‐dependent velocity and position of all involved trains. Several reformulation techniques are developed to obtain an equivalent mixed integer programming model with quadratic constraints (MIQCP) that can be solved to optimality by some commercial solvers. To improve the computational efficiency of the MIQCP model, we develop a dual decomposition solution framework that decomposes the primal problem into several sets of subproblems by dualizing the coupling constraints across different samples. An exact dynamic programming combined with search space reduction strategies is also developed to solve the exact optimal solutions of these subproblems. Two sets of numerical experiments, which involve a relatively small‐scale case and a real‐world instance based on the operation data of the Beijing subway Changping Line are implemented to verify the effectiveness of the proposed approaches. 相似文献
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127.
运用FDTD对时域天线阵进行仿真分析,并在外场进行测量研究。结果表明:阵列可以提高增益,增强方向性,该阵列天线适合于用作实际的超宽带雷达天线阵。 相似文献
128.
针对故障诊断专家系统中专家知识的模糊性和不确定性,给出用模糊Petri网(FPN)模型表示模糊产生式规则(FPR)知识的方法、知识的存储、模糊推理机制及算法的实现。同时,以JCS—020(FANUC)加工中心主轴伺服故障诊断为例,说明该方法在故障诊断专家系统(FDES)中应用的可行性与有效性。 相似文献
129.
Accelerated life testing (ALT) is commonly used to obtain reliability information about a product in a timely manner. Several stress loading designs have been proposed and recent research interests have emerged concerning the development of equivalent ALT plans. Step‐stress ALT (SSALT) is one of the most commonly used stress loadings because it usually shortens the test duration and reduces the number of required test units. This article considers two fundamental questions when designing a SSALT and provides formal proofs in answer to each. Namely: (1) can a simple SSALT be designed so that it is equivalent to other stress loading designs? (2) when optimizing a multilevel SSALT, does it degenerate to a simple SSALT plan? The answers to both queries, under certain reasonable model assumptions, are shown to be a qualified YES. In addition, we provide an argument to support the rationale of a common practice in designing a SSALT, that is, setting the higher stress level as high as possible in a SSALT plan. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2013 相似文献
130.
报道了采用亲和树脂法对相思子毒素蛋白进行反复的SELEX筛选,获得与靶物质结合率这32.5%的富集文库,并克隆得到了单克隆适配子序列,软件模拟了这些序列的二级结构,选择部分序列选择性剪切后利用荧光偏振方法进行检测,对靶蛋白的检测限达到亚nmol量。 相似文献