强爆轰驱动超高速碎片发射装置设计因素分析

为了得到发射装置设计因素和超高速碎片性能间的关系,考虑了药型罩的材料、炸药种类、装药长径比、药型罩的锥角、药型罩的厚度、药型罩顶部靠近装药侧的曲率半径等设计因素,采用AUTODYNTM,结合正交试验,对超高速碎片的发射过程进行数值模拟。结果表明,3种发射装置结构分别可以提供质量为1. 533 g的紫铜碎片、速度为11. 649 km/s的铝碎片、动能为85. 6 k J的铝碎片; 2种发射装置结构均可以提供质量大于1 g、速度高于11 km/s的密实结构圆柱状碎片。验证了仿真方法的可信性,对影响碎片性能的设计因素进行了分析、排序,并得到了这些设计因素与碎片质量、速度、动能的关系。     

空空导弹越肩发射初制导转弯控制与仿真

针对空空导弹越肩发射初制导俯仰平面180°转弯,提出了一种基于最优控制理论的最优转弯方法,该方法是确定一个最佳推力方向角,使转弯完成时导弹的末端速度最大。建立了简化的用于姿态控制的姿态动力学模型,采用反作用喷气控制系统(RCS)设计了导弹的姿态控制律。对空空导弹180°转弯的飞行过程进行了仿真并给出分析结果。     

聚能射流形成过程的理论建模与分析

分析了聚能射流的形成过程,并对其中的各阶段进行了详细建模。在模型中考虑了炸药爆轰、金属的驱动、药型罩压垮以及射流和杵体的形成过程。采用该模型对某一聚能装药结构进行了计算,计算结果表明:药型罩顶部和底部微元的压垮速度较小,在射流头部形成反向速度梯度,与试验数据吻合较好。该模型对于多级侵彻战斗部的工程设计与侵彻参数的计算具有一定的参考价值。     

A stochastic model for burn‐in procedures in accelerated environment

Burn‐in procedure is a manufacturing technique that is intended to eliminate early failures of system or product. Burning‐in a component or system means to subject it to a period of use prior to being used in field. Generally, burn‐in is considered expensive and so the length of burn‐in is typically limited. Thus, burn‐in is most often accomplished in an accelerated environment in order to shorten the burn‐in process. A new failure rate model for an accelerated burn‐in procedure, which incorporates the accelerated ageing process induced by the accelerated environmental stress, is proposed. Under a more general assumption on the shape of failure rate function of products, which includes the traditional bathtub‐shaped failure rate function as a special case, upper bounds for optimal burn‐in time will be derived. A numerical example will also be given for illustration. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006     

Optimal burn‐in procedure for periodically inspected systems

Burn‐in is a widely used method to improve the quality of products or systems after they have been produced. In this paper, we study burn‐in procedure for a system that is maintained under periodic inspection and perfect repair policy. Assuming that the underlying lifetime distribution of a system has an initially decreasing and/or eventually increasing failure rate function, we derive upper and lower bounds for the optimal burn‐in time, which maximizes the system availability. Furthermore, adopting an age replacement policy, we derive upper and lower bounds for the optimal age parameter of the replacement policy for each fixed burn‐in time and a uniform upper bound for the optimal burn‐in time given the age replacement policy. These results can be used to reduce the numerical work for determining both optimal burn‐in time and optimal replacement policy. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

东突恐怖主义成因分析

突厥文化和泛突厥主义的泛滥、伊斯兰复兴运动和泛伊斯兰主义的传播、新疆周边国家各种恐怖势力的影响、国际敌对势力的怂恿、改革开放以来国际交流的加强以及新疆特殊的地理位置 ,是我国新疆地区“东突”恐怖主义形成的重要条件 ,并对“东突”恐怖主义的泛滥起到了催化作用     

多孔材料药型罩聚能射流的形成条件

依据Herrmann状态方程和斜冲击波关系估算了多孔材料药型罩压垮之前的冲击温升,求解了经过冲击压缩卸载后材料的声速。给出了多孔材料药型罩聚能射流的形成条件。初始冲击温升会使材料的声速和强度降低,从而使多孔材料聚能射流形成射流的高速和低速条件降低。     

热射流起爆过程的数值模拟

采用改进的化学非平衡流解耦方法处理Euler反应流方程,并以H2/air 9组分21方程模型对竖直喷注的热射流起爆过程进行了二维数值模拟。对流项采用五阶WENO离散格式,时间推进采用二阶Runge-Kutta方法。详细分析了热射流以不同速度、入射位置、入射宽度和入射倾角喷射时在爆震管内形成的流场,总结了射流参数状态影响起爆的一般规律;解释了激波、火焰的相互作用对"热点"的形成以及转变为爆震的影响,特别是激波反射对"热点"形成的促进作用。结果表明,爆震波通常由火焰面和固壁附近狭长未燃区域中的"热点"产生。"热点"向爆震波发展的过程是过驱爆震阶段,存在三波结构。为了实现快速起爆,应当增大射流入射速度、贴近侧壁并以适当入射角度喷射热射流。     

基于自相关函数的信噪比估计方法

信噪比估计,作为衡量信道质量的标准,为许多自适应技术提供所需的信道信息。精确的信道质量估计值,可以有效提升这些技术的性能。研究表明,信号经过采样、发送波形成行后其自相关函数具有周期性。根据噪声和发送信号两者自相关函数的不同特性,提出一种利用自相关函数进行信噪比估计方法。仿真结果表明,该方法具有较高的估计精度。     

Selling to strategic and loss‐averse consumers: Stocking,procurement, and product design policies

Motivated by the presence of loss‐averse decision making behavior in practice, this article considers a supply chain consisting of a firm and strategic consumers who possess an S‐shaped loss‐averse utility function. In the model, consumers decide the purchase timing and the firm chooses the inventory level. We find that the loss‐averse consumers' strategic purchasing behavior is determined by their perceived gain and loss from strategic purchase delay, and the given rationing risk. Thus, the firm that is cognizant of this property tailors its inventory stocking policy based on the consumers' loss‐averse behavior such as their perceived values of gain and loss, and their sensitivity to them. We also demonstrate that the firm's equilibrium inventory stocking policy reflects both the economic logic of the traditional newsvendor inventory model, and the loss‐averse behavior of consumers. The equilibrium order quantity is significantly different from those derived from models that assume that the consumers are risk neutral and homogeneous in their valuations. We show that the firm that ignores strategic consumer's loss‐aversion behavior tends to keep an unnecessarily high inventory level that leads to excessive leftovers. Our numerical experiments further reveal that in some extreme cases the firm that ignores strategic consumer's loss‐aversion behavior generates almost 92% more leftovers than the firm that possesses consumers’ loss‐aversion information and takes it into account when making managerial decisions. To mitigate the consumer's forward‐looking behavior, we propose the adoption of the practice of agile supply chain management, which possesses the following attributes: (i) procuring inventory after observing real‐time demand information, (ii) enhanced design (which maintains the current production mix but improves the product performance to a higher level), and (iii) customized design (which maintains the current performance level but increases the variety of the current production line to meet consumers’ specific demands). We show that such a practice can induce the consumer to make early purchases by increasing their rationing risk, increasing the product value, or diversifying the product line. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 435–453, 2015