基于个体判断优先序的多目标群决策方法研究

针对多目标群决策问题,深入分析了群意见的形成方式.对基于方案优先序的多目标群决策问题给出了若干求解群排序的方法.对其求解原理和集结结果进行了对比,并分析了各方法的实质及其等价关系;澄清了一些模糊认识,指出了某些方法存在的问题,对此类多目标群决策问题的求解提供了依据.     

磁悬挂天平偏航电磁场的二维有限元分析

在磁悬挂天平偏航控制中,偏航线圈中的电流变化对模型姿态变化影响十分显著.为了提高天平的偏航控制精度,有必要对天平偏航电磁场进行更为精确的分析.该文采用有限单元法对磁悬挂天平偏航电磁场进行了分析,得到了比传统计算方法更为准确的结果,并在实验中进行了验证,从而为磁悬挂天平的偏航控制提供了参考.     

Data‐driven variation source identification for manufacturing process using the eigenspace comparison method

Variation reduction of manufacturing processes is an essential objective of process quality improvement. It is highly desirable to develop a methodology of variation source identification that helps quickly identify the variation sources, hence leading to quality improvement and cost reduction in manufacturing systems. This paper presents a variation source identification method based on the analysis of the covariance matrix of process quality measurements. The identification procedure utilizes the fact that the eigenspace of the quality measurement covariance matrix can be decomposed into a subspace due to variation sources and a subspace purely due to system noise. The former subspaces for different samples will be the same if the same variation sources dominate. A testing procedure is presented, which can determine the closeness of the subspaces under sampling uncertainty. A case study is conducted to illustrate the effectiveness of this methodology. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006.     

强侧风作用下棚车气动外形优化

铁路通用车型中,强侧风作用下棚车的气动性能最差。利用二维定常不可压缩N-S方程、k-ε两方程紊流模型,采用有限体积法对强侧风作用下棚车气动外形进行了优化研究。结果表明,棚车车顶形状对强侧风作用下棚车气动性能有较大影响,圆弧型车顶的P65型棚车气动性优于“人”字型车顶P64型棚车;棚车侧壁和车顶圆弧采用圆弧过渡比直接连接的效果好,综合考虑棚车气动性能和有效容量两方面因素,建议车顶圆弧和过渡圆弧半径分别取2692mm和500mm。     

基于AHP的装备研制项目风险分析方法

把AHP(Analytic H ierarchy Process)方法运用于装备研制项目风险分析,实现了风险因素的排序、系统总风险的评价以及风险响应措施的选择。在风险发生概率和风险损失的基础上,将风险因素的可控制性和用户满意度风险也同时作为风险判断准则,使得风险的评价更合理、更准确地反映项目实际。最后给出了风险因素排序及风险响应措施选择的应用实例。     

回归分析在漏磁定量检测中的应用

通过分析漏磁场,选取法向分量的峰峰值和峰峰值间距作为漏磁通信号的特征量。重点介绍了多元回归分析模型理论、参数估计方法和回归模型的假设检验,得到缺陷宽度、深度与峰峰值和峰峰值间距之间的回归模型,最后利用漏磁数据对回归模型进行了检验,结果表明预测缺陷宽度和深度的误差不超过10%,利用回归分析能够实现漏磁检测的定量化。     

导弹服役年限建模与分析

影响导弹服役年限的主要因素有自然因素、技术因素以及经济因素。合理地确定导弹的服役年限,是减少军费开支、降低导弹全寿命费用的有效途径。从导弹服役年限的概念入手,在提出用经济寿命法确定导弹的服役年限的基础上,通过数学分析,建立经济模型和经济比较模型,确定了导弹服役年限,并结合实例进行了仿真和验证,从而证明了模型的实际应用价值。     

Research on the intermediate phase of 40CrMnSiB steel shell under different heat treatments

In this study, 40CrMnSiB steel cylindrical shells were tempered at 350, 500 and 600 ℃ to study the effect of tempering temperature on the dynamic process of expansion and fracture of the metal shell. A mid-explosion recovery experiment for the metal cylinder under internal explosive loading was designed, and the wreckage of the casings at the intermediate phase was obtained. The effects of different tempering temperatures on the macroscopic and microscopic fracture characteristics of 40CrMnSiB steel were studied. The influence of tempering temperatures on the fracture characteristic parameters of the recovered wreckage were measured and analyzed, including the circumferential divide size, the thick-ness and the number of the circumferential divisions. The results show that as the tempering temper-ature was increased from 350 to 600 ℃, at first, the degree of fragmentation and the fracture characteristic parameters of the recovered wreckage changed significantly and then became essentially consistent. Scanning electron microscopy analysis revealed flow-like structure characteristics caused by adiabatic shear on different fracture surfaces. At the detonation initiation end of the casing, fracturing was formed by tearing along the crack, which existed a distance from the initiation end and propagated along the axis direction. In contrast, the fracturing near the middle position consists of a plurality of radial shear fracture units. The amount of alloy carbide that was precipitated during the tempering process increased continuously with tempering temperature, leading to an increasing number of spherical carbide particles scattered around the fracture surface.     

Thermal and combustion behavior of Al-MnO2 nanothermite with poly(vinylidene fluoride -co- hexafluoropropylene) energetic binder

Fluoropolymers get increasing attention in energetic materials application due to the high fluorine content. To explore the effect of poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) on Al/MnO2 nanothermite, the samples with different contents are prepared and characterized by SEM, TG-DSC, XRD, and their ignition and combustion behavior are tested and recorded. The results show that P(VDF-HFP) as an energetic binder can combine the nanothermite components together, even exist in the gaps. The integrity of energetic materials has been improved. Thermal analysis shows that the addition of P(VDF-HFP) greatly changes the thermal reaction processes, and the exothermic peaks appear early, but the utilization of fuel and oxidizer is not efficient from the XRD results. Furthermore, the appropriate addition of P(VDF-HFP) can directly reduce the ignition energy threshold and increase the combustion time, which is necessary for the potential ignition charge application. The possible reasons for above phenomena are discussed and analyzed. This research provides a reference for improvement of thermite-based ignition charge formulation.