哈萨克斯坦哈萨克族大学生语言状况调查

哈萨克斯坦是一个多民族的国家,独立后推行的第一部《语言法》已经有20多年的历史.通过调查哈萨克斯坦高校哈萨克族大学生的语言状况,分析哈萨克族大学生在家庭、学校、社会、网络等方面的语言使用状况,学生对哈萨克语、俄语、英语的态度,三种语言的能力状况,从而分析新《语言法》在哈萨克斯坦推行的效果.     

三语习得视域下的新疆少数民族大学生英语学习

目前,西方对三语习得的研究不断深入,但国内对少数民族地区的三语习得研究亟需关注与深入探索.因此,本文从三语习得探讨新疆少数民族大学生英语学习,以期通过分析提高新疆少数民族大学生英语水平、跨文化交际能力和多元文化的素质,并为国内少数民族地区的三语习得研究供以借鉴.     

基于 DoDAF 电子对抗训练导控系统体系结构设计

电子对抗训练导控系统是集电子对抗部队训练导调、指挥、控制、裁决、评估和管理等功能需求于一体的综合性军事信息系统。依据美国防部体系结构框架标准规范,结合电子对抗训练需求,按照结构化的设计方法,对电子对抗训练导控系统体系结构进行了初步设计,包括系统功能定位、指挥关系、指挥流程和接口关系等,希望为系统建设提供参考借鉴。     

高功率微波车辆迫停的效应机理分析

通过分析车辆电子控制单元输出的点火开关和燃油喷射信号波形在高功率微波辐射条件下的演变过程,阐明了高功率微波致使车辆发动机熄火的原因。研究结果表明,电子控制单元受到微波辐射扰乱后,点火开关信号发生意外丢失,燃油喷射信号脉冲重复周期迅速缩短,造成发动机气缸内喷入过量燃油,火花塞无法点燃油气混合物,迫使发动机转速下降甚至熄火。通过分析车辆发动机的点火系统工作原理,提出了根据监测车体辐射电磁信号获取车辆易受攻击的敏感频段的试验思路。     

高精度空间非合作式相对轨道状态预报

为了解决接近空间非合作目标过程中的相对导航问题,提出一种基于相对轨道动力学方程和二阶龙格库塔积分公式的高精度空间非合作目标相对轨道预报模型。考虑地球J2摄动加速度,将目标轨道方程在参考轨道附近展开,保留至引力加速度差的二阶展开项,并进一步推导考虑J2摄动的参考轨道角速度和角加速度,建立相对轨道动力学微分方程;在给定相对轨道初值的情况下,采用二阶龙格库塔积分公式进行相对轨道预报。该模型采用数值积分方法,对相对轨道动力学模型形式没有限制,通用性好,适用范围广;选择低阶龙格库塔公式积分预报,既减少了计算量又保证了计算精度。设置高轨和低轨两种相对运动仿真场景,仿真结果表明了模型的通用性和精确性。     

相依网络研究综述

网络相依性和相依网络研究已经成为近年来复杂网络领域的热点,但是目前对相关研究进展进行综合归纳的文献却不多见。在对国内外相关文献进行系统分析的基础上,简要介绍相依网络研究涉及的渗流理论;描述该类型网络的级联失效过程;从相依网络的子网络特性、相依边的方向和类型、子网络组合方式等三个角度对相依网络鲁棒性的研究成果进行总结;并从理论和应用两方面对未来相依网络研究的发展方向进行展望。     

天波超视距雷达作战效能评估研究

为了充分考虑天波超视距雷达作战效能指标体系中各层次指标之间的聚合关系,更加贴切反映装备的真实效能,将"逻辑门"的思想应用到天波超视距雷达作战效能指标的聚合中,构建了基于"逻辑门"的天波超视距雷达作战效能评估指标层次体系,解决了指标聚合方式单一化的问题,实例表明该作战效能计算模型的正确性.     

Nonperiodic preventive maintenance for repairable systems

As a complex system with multiple components usually deteriorates with age, preventive maintenance (PM) is often performed to keep the system functioning in a good state to prolong its effective age. In this study, a nonhomogeneous Poisson process with a power law failure intensity is used to describe the deterioration of a repairable system, and the optimal nonperiodic PM schedule can be determined to minimize the expected total cost per unit time. However, since the determination of such optimal PM policies may involve numerous uncertainties, which typically make the analyses difficult to perform because of the scarcity of data, a Bayesian decision model, which utilizes all available information effectively, is also proposed for determining the optimal PM strategies. A numerical example with a real failure data set is used to illustrate the effectiveness of the proposed approach. The results show that the optimal schedules derived by Bayesian approach are relatively more conservative than that for non‐Bayesian approach because of the uncertainty of the intensity function, and if the intensity function are updated using the collected data set, which indicates more severe deterioration than the prior belief, replacing the entire system instead of frequent PM activities before serious deterioration is suggested. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

Approximation results for min‐max path cover problems in vehicle routing

This article studies a min‐max path cover problem, which is to determine a set of paths for k capacitated vehicles to service all the customers in a given weighted graph so that the largest path cost is minimized. The problem has wide applications in vehicle routing, especially when the minimization of the latest service completion time is a critical performance measure. We have analyzed four typical variants of this problem, where the vehicles have either unlimited or limited capacities, and they start from either a given depot or any depot of a given depot set. We have developed approximation algorithms for these four variants, which achieve approximation ratios of max{3 ‐ 2/k,2}, 5, max{5 ‐ 2/k,4}, and 7, respectively. We have also analyzed the approximation hardness of these variants by showing that, unless P = NP , it is impossible for them to achieve approximation ratios less than 4/3, 3/2, 3/2, and 2, respectively. We have further extended the techniques and results developed for this problem to other min‐max vehicle routing problems.© 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

基于GM-ANP的维修人员保障能力评估

以维修人员保障能力评估指标体系为基础,建立基于GM-ANP的维修人员保障能力评估模型。采用网络分析法(ANP)确定各因素的权重,运用超级决策SD软件辅助计算权重;用灰色聚类评估方法(GM),确定评估样本矩阵和评估灰类,计算灰色评估权矩阵;综合权重和评估权矩阵,得出评估结果。通过实例计算表明这种评估模型的有效性和实用性。