排序方式: 共有91条查询结果,搜索用时 15 毫秒
11.
12.
《防务技术》2014,10(4):349-353
In order to explore the rules of the deformation force during the launching of a small-diameter steel cartridge, the semi-closed bomb test method is used to test the greatest strains on chamber outer wall under the different chamber pressures. The pressure curves of cartridge chamber are measured in experiment, and the tensile test data of cartridge are loaded into the numerical calculation to compare with the experimental data. The conclusion was obtained that the calculated results match better with the experimental results by considering strain rate bilinear kinematic hardening material constitutive model. The forces on the various parts of the cartridge during launching and their deformation rules are achieved, in which the equivalent plastic strain decreases and the cylinder ring withstands the maximum equivalent stress when the cartridge case clings to the bore from the mouth to the bottom. 相似文献
13.
基于案例推理和模糊诊断的兵器故障诊断专家系统 总被引:5,自引:0,他引:5
讨论了基于案例的推理和模糊诊断矩阵在兵器故障中的应用 ,建立了兵器故障诊断WDDS -E系统模型和模糊诊断矩阵模型。详细说明了系统的工作原理和设计过程 ,并给出了应用实例 相似文献
14.
Fangruo Chen 《海军后勤学研究》2000,47(5):422-439
Consider a distribution system with a central warehouse and multiple retailers. Customer demand arrives at each of the retailers continuously at a constant rate. The retailers replenish their inventories from the warehouse which in turn orders from an outside supplier with unlimited stock. There are economies of scale in replenishing the inventories at both the warehouse and the retail level. Stockouts at the retailers are backlogged. The system incurs holding and backorder costs. The objective is to minimize the long‐run average total cost in the system. This paper studies the cost effectiveness of (R, Q) policies in the above system. Under an (R, Q) policy, each facility orders a fixed quantity Q from its supplier every time its inventory position reaches a reorder point R. It is shown that (R, Q) policies are at least 76% effective. Numerical examples are provided to further illustrate the cost effectiveness of (R, Q) policies. © 2000 John Wiley & Sons, Inc. Naval Research Logistics 47: 422–439, 2000 相似文献
15.
分析了双37舰炮射击终止时产生弹壳贴膛,退壳困难的故障,详细探讨故障产生原因,提出在装备使用过程中,使机械和电气的动作能相互制约,相互控制,避免射击终止时弹壳贴膛的改进措施。 相似文献
16.
分析了某型舰炮方向机蜗轮蜗杆箱的失效原因,提出了采用以缓冲机构为主体的改进方案,在对原机构不作大改动的条件下,提高了该机构的承载能力和使用寿命,改善了受力条件和工作条件,并易于生产和推广应用。 相似文献
17.
在假定每次校对费用可能不一样且带来一定收益的条件下,讨论了校对问题的最优停止,给出了Poisson模型与二项模型的最优停时。 相似文献
18.
19.
某型25mm自动炮存在闩体阻挡抛壳现象,为查找其原因,文章从自动炮结构到设计图纸进行了分析,找出了闩体下降滞后导致闩体阻挡抛壳的原因,并对闩体阻挡抛壳所带来后果及改进方法提出了看法。 相似文献
20.
The service‐provision problem described in this paper comes from an application of distributed processing in telecommunications networks. The objective is to maximize a service provider's profit from offering computational‐based services to customers. The service provider has limited capacity and must choose which of a set of software applications he would like to offer. This can be done dynamically, taking into consideration that demand for the different services is uncertain. The problem is examined in the framework of stochastic integer programming. Approximations and complexity are examined for the case when demand is described by a discrete probability distribution. For the deterministic counterpart, a fully polynomial approximation scheme is known 2 . We show that introduction of stochasticity makes the problem strongly NP‐hard, implying that the existence of such a scheme for the stochastic problem is highly unlikely. For the general case a heuristic with a worst‐case performance ratio that increases in the number of scenarios is presented. Restricting the class of problem instances in a way that many reasonable practical problem instances satisfy allows for the derivation of a heuristic with a constant worst‐case performance ratio. Worst‐case performance analysis of approximation algorithms is classical in the field of combinatorial optimization, but in stochastic programming the authors are not aware of any previous results in this direction. © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2003 相似文献