新疆固定资产投资环境与趋势分析

截止目前,新疆固定资产投资运行情况比较平稳,与全国相比,投资增速处于中等水平。全社会固定资产投资预计完成1595亿元,增长18％。建成和开工建设了一大批重大基础设施和重点基础产业项目,投资结构进一步改善,农业、水利、交通、能源、生态建设、社会事业等薄弱环节投资力度明显加大,生态环境保护建设取得明显成效。     

球齿轮传动的齿面接触分析和应力分析

球齿轮是一种新型的二维齿轮传动机构.在建立了球齿轮数学模型的基础上,得到了球齿轮传动的啮合模型,并进行了齿面接触特性分析,通过解非线性方程组,可得到接触点在齿面的位置.分析了球齿轮齿面的结构特征,针对球齿轮传动的接触形式表现为轮齿凸面与马鞍面之间的点接触,对啮合齿面的接触椭圆进行了分析计算,总结出了球齿轮在任一偏摆平面内啮合传动时接触椭圆的变化规律:在轮齿根部和顶部啮合时,接触椭圆较小,因而接触应力较大;而在轮齿中部啮合时,接触椭圆较大,所以接触应力较小.采用有限元的方法对球齿轮轮齿进行了弯曲应力和接触应力分析,分析结果进一步验证了接触椭圆变化规律的正确性.以上结论对进一步研究球齿轮的传动理论与实际应用具有重要的指导意义.     

A componentwise index of service measurement in multi‐component systems

In this paper we present a componentwise delay measure for estimating and improving the expected delays experienced by customers in a multi‐component inventory/assembly system. We show that this measure is easily computed. Further, in an environment where the performance of each of the item delays could be improved with investment, we present a solution that aims to minimize this measure and, in effect, minimizes the average waiting time experienced by customers. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 50: 2003     

末敏子母弹落点的近似模拟

攻击线目标的末敏子母弹是一种新型弹种 ,具有较高的射击效力。在分析末敏子母弹抛撒和运动特性的基础上 ,提出近似模拟末敏子弹落点的方法 ,分析过程简单、快速 ,结果具有一定的可信性 ,为近似分析末敏子母弹武器系统射击效力提供了参考工具     

地球模型偏差对远程弹箭弹道仿真的影响及修正

针对地球模型精确度影响远程弹箭弹道仿真的问题,分析了地球模型偏差对弹道仿真精度的影响并加以修正。采用总的地球椭球系,在已有弹道模型的基础上,分析了垂线偏差的产生机理及其对定向定位参数的影响,并由此得出弹道几何偏移随定向偏差的变化规律,研究了引力加速度初值偏差对弹道的误差累积,并对由水准面不平行性造成的实际落点高差进行了理论推导。对比仿真算例表明,考虑地球模型偏差影响的仿真结果与不考虑的情况下差别较明显,在远程条件下对弹道仿真精度的影响不容忽视。     

飞航导弹故障飞行落点概率计算方法

针对飞航导弹故障飞行落点概率难以准确计算的问题,通过分析导弹的各个分系统的故障机理重新提出五种故障模式,依据逐系统串联的原理建立了故障模式的概率分配计算模型;在对发射、飞行和故障后坠落等阶段进行分析的基础上建立各故障模式的仿真模型;最后应用蒙特卡洛方法对某型导弹故障飞行落点的概率分布进行了仿真计算。     

Sensor placement in active multistatic sonar networks

The idea of deploying noncollocated sources and receivers in multistatic sonar networks (MSNs) has emerged as a promising area of opportunity in sonar systems. This article is one of the first to address point coverage problems in MSNs, where a number of points of interest have to be monitored in order to protect them from hostile underwater assets. We consider discrete “definite range” sensors as well as various diffuse sensor models. We make several new contributions. By showing that the convex hull spanned by the targets is guaranteed to contain optimal sensor positions, we are able to limit the solution space. Under a definite range sensor model, we are able to exclude even more suboptimal solutions. We then formulate a nonlinear program and an integer nonlinear program to express the sensor placement problem. To address the nonconvex single‐source placement problem, we develop the Divide Best Sector (DiBS) algorithm, which quickly provides an optimal source position assuming fixed receivers. Starting with a basic implementation of DiBS, we show how incorporating advanced sector splitting methods and termination conditions further improve the algorithm. We also discuss two ways to use DiBS to find multiple source positions by placing sensors iteratively or simultaneously. © 2017 Wiley Periodicals, Inc. Naval Research Logistics 64: 287–304, 2017     

Preemptive parallel‐machine scheduling with a common server to minimize makespan

We consider parallel‐machine scheduling with a common server and job preemption to minimize the makespan. While the non‐preemptive version of the problem is strongly NP‐hard, the complexity status of the preemptive version has remained open. We show that the preemptive version is NP‐hard even if there is a fixed number of machines. We give a pseudo‐polynomial time algorithm to solve the case with two machines. We show that the case with an arbitrary number of machines is unary NP‐hard, analyze the performance ratios of some natural heuristic algorithms, and present several solvable special cases. © 2017 Wiley Periodicals, Inc. Naval Research Logistics 64: 388–398, 2017     

滑模控制的新型双幂次组合函数趋近律

提出一种基于双幂次组合函数趋近律的新型滑模控制方案。与现有的快速幂次或双幂次趋近律相比,具有更快的收敛速度,同时还保持了全局固定时间收敛特性,收敛时间上界与滑模初值无关。当系统存在有界扰动时,能够使滑模变量在有限时间内收敛到稳态误差界内,同时其稳态误差要小于现有方法的。仿真实验验证了该方法的有效性及理论分析的正确性。     

融合空间偏好和语义的个体活动识别方法

个体活动识别对用户画像、个性化推荐、异常行为检测、群体行为分析和基于活动的资源配置优化具有重要价值。提出了一种基于稀疏的社交媒体签到数据的个体活动语义识别方法,从签到数据中提取活动行为的时间周期性和趋势性特征,并采用空间偏好量化算法,从个体与群体活动的空间关联中提取群体和个体的空间访问偏好,使用自然语言嵌入工具BERT模型提取访问兴趣点的语义。时间特征、空间偏好特征和访问兴趣点名称语义特征共同构成表征群体、个体偏好的时空联合特征,通过极限梯度提升分类器对其进行分类,得到活动语义识别结果。在Foursquare数据集上的对比实验和消融实验中验证了所提活动语义识别模型可以有效提升活动语义识别的准确性。