基于模糊评判的某行星转向机故障预测研究

为了实现对自行火炮传动系统的预测维修,以行星转向机为例,运用动态模糊综合评判的办法,提取引起行星转向机典型故障的关键影响因素,探讨了动态模糊判断矩阵和动态权重的确定方法,在此基础上确定了其动态预测模型,并用实例验证了模型的正确性。     

When are observed failures more informative than observed survivals?

A framework involving independent competing risks permits observing failures due to a specific cause and failures due to a competing cause, which constitute survival times from the cause of primary interest. Is observing more failures more informative than observing survivals? Intuitively, due to the definitiveness of failures, the answer seems to be the former. However, it has been shown before that this intuition holds when estimating the mean but not the failure rate of the exponential model with a gamma prior distribution for the failure rate. In this article, we address this question at a more general level. We show that for a certain class of distributions failures can be more informative than survivals for prediction of life length and vice versa for some others. We also show that for a large class of lifetime models, failure is less informative than survival for estimating the proportional hazards parameter with gamma, Jeffreys, and uniform priors. We further show that, for this class of lifetime models, on average, failure is more informative than survival for parameter estimation and for prediction. These results imply that the inferential purpose and properties of the lifetime distribution are germane for conducting life tests. © 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013     

The incentive effect of acceptance sampling plans in a supply chain with endogenous product quality

This article studies a firm that procures a product from a supplier. The quality of each product unit is measured by a continuous variable that follows a normal distribution and is correlated within a batch. The firm conducts an inspection and pays the supplier only if the product batch passes the inspection. The inspection not only serves the purpose of preventing a bad batch from reaching customers but also offers the supplier an incentive to improve product quality. The firm determines the acceptance sampling plan, and the supplier determines the quality effort level in either a simultaneous game or a Stackelberg leadership game, in which both parties share inspection cost and recall loss caused by low product quality. In the simultaneous game, we identify the Nash equilibrium form, provide sufficient conditions that guarantee the existence of a pure strategy Nash equilibrium, and find parameter settings under which the decentralized and centralized supply chains achieve the same outcome. By numerical experiments, we show that the firm's acceptance sampling plan and the supplier's quality effort level are sensitive to both the recall loss sharing ratio and the game format (i.e., the precommitment assumption of the inspection policy). © 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013     

基于电磁防护仿生方法的赛博空域鲁棒性研究

阐述赛博空域研究工作中以仿生方式进行电磁防护所需要涉及的基本内容,对所研究的内容在整个仿生领域中予以大致的定位．对赛博空域进行定义,解释进行电磁防护的基本概念、相关仿生研究的表象级对等模型、研究策略和实现基础．根据结构和功能的关系进行相应方案的规划,并结合鲁棒性研究,在分级冗余基础上考虑鲁棒裕度问题,描述网络简并、功能梯度和旁路易化的特征,使得赛博环境下电磁防护的仿生构想在技术上成为可能．     

内腐蚀缺陷尺寸对DN150承插管线承压能力的影响

为了科学地指导DN150承插管线的使用与管理,采用非线性有限元法对带内腐蚀缺陷的DN150承插管线进行了剩余强度的评估。通过分析和计算,研究了腐蚀缺陷宽度、长度和深度对管线极限承载能力的影响。结果表明：腐蚀缺陷宽度对DN150承插管线的承载能力影响很小,可忽略不计;随着腐蚀缺陷长度的增加,管线的承载能力略微减小,当缺陷长度达到150mm,管道失效压力基本不变;随着腐蚀缺陷深度的增加,管道失效压力呈线性递减,其对管道失效压力的影响程度远远大于腐蚀缺陷长度。     

STCN的对岸打击时间协同冲突消解研究

为验证航空兵对岸打击中时间协同计划的可行性以及快速地调整时间协同计划,建立了任务间的简单时间约束网络(STCN),并转化成权值矩阵的形式.根据权值矩阵特点,提出了一种检测STCN一致性的权值矩阵法,大大降低了算法复杂度.为加快时间协同计划的调整速度,基于检测结果,提出了一种代价最小的冲突消解方法,避免了消解过程中的重复检测问题,提高了效率,使计划调整更加快捷高效.     

Numerical investigation of the failure mechanism of cubic concrete specimens in SHPB tests

Cylindrical specimens are commonly used in Split Hopkinson pressure bar (SHPB) tests to study the uniaxial dynamic properties of concrete-like materials.In recent years,true tri-axial SHPB equipment has also been developed or is under development to investigate the material dynamic properties under tri-axial impact loads.For such tests,cubic specimens are needed.It is well understood that static material strength obtained from cylinder and cube specimens are different.Conversion factors are obtained and adopted in some guidelines to convert the material strength obtained from the two types of specimens.Previous uniaxial impact tests have also demonstrated that the failure mode and the strain rate effect of cubic specimens are very different from that of cylindrical ones.However,the mechanical background of these findings is unclear.As an extension of the previous laboratory study,this study performs numerical SHPB tests of cubic and cylindrical concrete specimens subjected to uniaxial impact load with the validated numerical model.The stress states of cubic specimens in relation to its failure mode under different strain rates is analyzed and compared with cylindrical specimens.The detailed analyses of the numerical simulation results show that the lateral inertial confinement of the cylindrical specimen is higher than that of the cubic specimen under the same strain rates.For cubic specimen,the corners are more severely damaged because of the lower lateral confinement and the occurrence of the tensile radial stress which is not observed in cylindrical specimens.These results explain why the dynamic material strengths obtained from the two types of specimens are different and are strain rate dependent.Based on the simulation results,an empirical formula of conversion factor as a function of strain rate is proposed,which supplements the traditional conversion factor for quasi-static material strength.It can be used for transforming the dynamic compressive strength from cylinders to cubes obtained from impact tests at different strain rates.     

钢框架梁柱焊接连接抗震性能试验研究

以梁端腹板的扇形孔形状为主要参数,进行了4个足尺钢框架梁柱焊接节点往复加载下的破坏试验。通过对弯矩—塑性转角和弯矩—累积塑性变形倍率试验曲线对比分析表明,扇形孔是节点变形能力和破坏形式的主要影响因素。改进扇形孔构造是一种有效措施,既可提高节点的抗震性能,又能保持制作工艺与传统节点基本相同。     

Some probability functions in reliability and their applications

There has been much research on the general failure model recently. In the general failure model, when the unit fails at its age t, Type I failure (minor failure) occurs with probability 1 ? p(t) and Type II failure (catastrophic failure) occurs with probability p(t). In the previous research, some specific shapes (constant, non‐decreasing, or bathtub‐shape) on the probability function p(t) are assumed. In this article, general results on some probability functions are obtained and applied to study the shapes of p(t). The results are also applied to determining the optimal inspection and allocation policies in maintenance problems. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

加强和改进消防行政执法之我见

消防行政执法是公安消防机构最主要的职责和基本活动,是消防执法人员的经常性工作。根据形势发展对消防行政执法的要求,结合消防行政执法实践,揭示了当前行政执法中存在的问题及其致因,并提出了加强和改进消防行政执法的基本对策。