矿物掺合料对GRC耐久性的影响

通过长达3年的标准养护试验及80℃热水加速老化试验,研究了矿物掺合料粉煤灰、硅灰对耐碱玻璃纤维增强普通硅酸盐水泥(GRC)耐久性的影响,并对矿物掺合料改善GRC耐久性的机理作了初步分析探讨。研究结果表明,粉煤灰和硅灰矿物掺合料可明显改善GRC的长期耐久性。     

美军飞机易损性实弹测试现状及启示

飞机易损性分析与评估是指对飞机在战斗状态下遭受攻击后受损的难易程度的评价,是衡量飞机战斗性能的重要指标.研究飞机易损性对于飞机高生存力设计和飞机战伤预测评估具有重要意义.本文首先简要介绍了飞机易损性分析的一般方法与流程,收集并整理了美军飞机易损性实弹测试的历史沿革和条件建设现状,同时以F-35整机、F135发动机和C2...     

陆军导弹武器系统测试性研究

针对陆军导弹武器系统的特点,论述了系统测试性和系统测试性设计的基本概念,在解释它们内涵的同时,说明了如何从本质上理解它们在导弹武器系统全寿命周期中的重要作用。为了保持系统的良好测试性,从定量和定性两个方面提出了测试性设计的基本要求,研究了提高系统测试性的主要方法。     

火炮身管寿命分析与计算

分析了射击时弹丸挤进过程 ,建立了弹丸初速下降量与炮膛内膛磨损量计算模型 ,并以某火炮为实例计算了该炮弹丸初速下降量与炮膛内膛磨损量之间变化关系 ,分析了弹道峰现象 ,为身管寿命预测提供理论依据     

Estimating distribution functions from partially observed samples

Suppose that some components are initially operated in a certain condition and then switched to operating in a different condition. Working hours of the components in condition 1 and condition 2 are respectively observed. Of interest is the lifetime distribution F of the component in the second condition only, i.e., the distribution without the prior exposure to the first condition. In this paper, we propose a method to transform the lifetime obtained in condition 1 to an equivalent lifetime in condition 2 and then use the transformed data to estimate F. Both parametric and nonparametric approaches each with complete and censored data are discussed. Numerical studies are presented to investigate the performance of the method. © 2000 John Wiley & Sons, Inc. Naval Research Logistics 47: 521–530, 2000     

温度对半导体激光器退化的影响

采取等效电路模型仿真和加速退化试验相结合的方法研究温度对半导体激光器不同退化模式的影响规律。针对半导体激光器有源区退化和腔面退化进行分析,发现有源区退化会使半导体激光器阈值电流增大,而腔面退化会使半导体激光器斜率效率减小;进行了半导体激光器热特性建模与仿真,发现温度升高会使半导体激光器阈值电流增大;利用半导体激光器加速退化试验平台进行了半导体激光器加速退化试验。仿真与试验结果证明:温度升高会加剧半导体激光器腔面退化,而对有源区退化无显著影响。上述结论对进一步完善半导体激光器温度-退化仿真模型,研究温度对半导体激光器退化的作用机理和防护措施有积极作用。     

Global planning of accelerated degradation tests based on exponential dispersion degradation models

The accelerated degradation test (ADT) is an efficient tool for assessing the lifetime information of highly reliable products. However, conducting an ADT is very expensive. Therefore, how to conduct a cost-constrained ADT plan is a great challenging issue for reliability analysts. By taking the experimental cost into consideration, this paper proposes a semi-analytical procedure to determine the total sample size, testing stress levels, the measurement frequencies, and the number of measurements (within a degradation path) globally under a class of exponential dispersion degradation models. The proposed method is also extended to determine the global planning of a three-level compromise plan. The advantage of the proposed method not only provides better design insights for conducting an ADT plan, but also provides an efficient algorithm to obtain a cost-constrained ADT plan, compared with conventional optimal plans by grid search algorithms.     

数据基故障诊断算法更新问题研究

机内测试被广泛应用于故障诊断、装备健康管理与预测等领域。针对机内测试设备在设计和升级时遇到的分类器更新、样本数量不平衡、硬件条件限制问题,提出初步解决方案。利用基于密度的聚类和人工免疫方法处理原始数据;提出基于代表样本点的混合学习方法;利用支持向量机和仿真案例验证所提方法。结果表明所提方法能够解决上述问题,有助于基于数据的机内测试设备设计与升级。     

发动机粘接界面加速老化及寿命预测

介绍发动机粘接界面老化试验,根据其力学特性的变化,建立合适的数学模型,并估算出贮存寿命。     

影响听力测试的几个因素

本文根据多年教学实践,探讨了英语听力教学的状况,分析了影响听力理解在测试中的外在及内在因素,并提出了可行性的建议。