舰船水下静态电场深度换算的格林函数法

为从有限深度、有限范围内的舰船水下静态电场数据获知实际舰船更大深度上的场分布特征,在对深海环境中舰船静态电场满足的拉普拉斯方程进行求解的基础上,提出静态电场深度换算的格林函数法,推导出了换算公式的边界积分表达式,给出了实际应用中换算公式的近似计算方法。以舰船静态电场的基本模拟体——单个水平电偶极子的场为例,采用数值仿真的方法对换算公式进行了验证,并对近似计算方法进行了讨论。研究结果表明:该方法可直接通过对测量平面上离散场量进行二重求和来实现静态电场的各类深度换算;与文献中已有的换算方法相比,其换算过程更为快捷。     

压力喷嘴常温下雾化特性实验研究

为了满足工程中对喷嘴雾化特性测量的高精度、低成本要求,建立了喷嘴雾化特性实验系统,以自来水为雾化工质,对蒸发冷却压力喷嘴在常温、常压下的雾化特性进行了实验研究。用容积法测量了喷嘴的流量,用最小二乘法对测量数据进行回归分析,得到了喷嘴流量、雾化压力和喷孔直径之间的关联式与流量系数;用机器视觉方法测量了喷嘴的雾化锥角与雾滴尺寸,得到了雾化锥角与雾滴尺寸随雾化压力变化的规律。结果表明:随着雾化压力的增大,喷嘴雾化锥角不断增加,雾滴尺寸不断减小;随轴向距离的增大,D0.632、D0.5、D32有不同幅度的增大,而D0.9则基本不变。     

面向CPS的一体化标识网络结构研究

对信息与物理融合系统（Cyber—Physical System,CPS）体系结构及其标识机制进行了系统分析,对基于资源港（Port）的体系结构进行了设计,提出了三层一体化标识网络结构模型,并设计Port层模型作为CPS资源寻址定位和建立通信连接的重要中间件层。最后,以一个智能家居原型系统为例,对一体化标识结构关于支持用户对CPS资源访问与管控的可行性进行了验证。     

电磁屏蔽模型房接地性能实验研究

接地是建筑物实现宽频电磁屏蔽的重要技术措施,而导电的屏蔽功能层与接地系统电连接后也反过来影响接地的性能指标。采用导电混凝土为主料制作接地电极和电磁屏蔽模型房,测试单屏蔽模型房悬空、单电极-单屏蔽模型房接地以及单电极-双屏蔽模型房并联接地3种情况下的接地电阻变化规律。实验发现,屏蔽功能层本身可以等效为一个电阻,与接地系统并联后可以有效降低接地电阻;屏蔽功能层面积越大,电阻降低越多。实验结果可以为建筑物电磁屏蔽工程的接地设计与实践提供参考。     

基于STK的动能反卫作战信息流程构建

介绍了动能反卫星武器的信息系统构成及功能,对动能反卫作战过程进行了描述,提出了动能反卫作战中的信息需求,构建了动能反卫作战行动的信息流程。详细介绍了动能反卫星作战流程,并对作战信息需求进行分析。最后,利用卫星工具包(STK)实现一次对地基动能反卫星作战过程的仿真。     

Flow‐shop batch scheduling with identical processing‐time jobs

In many practical situations of production scheduling, it is either necessary or recommended to group a large number of jobs into a relatively small number of batches. A decision needs to be made regarding both the batching (i.e., determining the number and the size of the batches) and the sequencing (of batches and of jobs within batches). A setup cost is incurred whenever a batch begins processing on a given machine. This paper focuses on batch scheduling of identical processing‐time jobs, and machine‐ and sequence‐independent setup times on an m‐machine flow‐shop. The objective is to find an allocation to batches and their schedule in order to minimize flow‐time. We introduce a surprising and nonintuitive solution for the problem. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004     

Two‐machine flow shop no‐wait scheduling with a nonavailability interval

We study a two‐machine flow shop scheduling problem with no‐wait in process, in which one of the machines is not available during a specified time interval. We consider three scenarios of handing the operation affected by the nonavailability interval. Its processing may (i) start from scratch after the interval, or (ii) be resumed from the point of interruption, or (iii) be partially restarted after the interval. The objective is to minimize the makespan. We present an approximation algorithm that for all these scenarios delivers a worst‐case ratio of 3/2. For the second scenario, we offer a 4/3‐approximation algorithm. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004     

An efficient SPH methodology for modelling mechanical characteristics of particulate composites

Particulate composites are one of the widely used materials in producing numerous state-of-the-art components in biomedical, automobile, aerospace including defence technology. Variety of modelling techniques have been adopted in the past to model mechanical behaviour of particulate composites. Due to their favourable properties, particle-based methods provide a convenient platform to model failure or fracture of these composites. Smooth particle hydrodynamics (SPH) is one of such methods which demonstrate excellent potential for modelling failure or fracture of particulate composites in a Lagrangian setting. One of the major challenges in using SPH method for modelling composite materials depends on accurate and efficient way to treat interface and boundary conditions. In this paper, a master-slave method based multi-freedom constraints is proposed to impose essential boundary conditions and interfacial displacement constraints in modelling mechanical behaviour of composite materials using SPH method. The proposed methodology enforces the above constraints more accurately and requires only smaller condition number for system stiffness matrix than the procedures based on typical penalty function approach. A minimum cut-off value-based error criteria is employed to improve the compu-tational efficiency of the proposed methodology. In addition, the proposed method is further enhanced by adopting a modified numerical interpolation scheme along the boundary to increase the accuracy and computational efficiency. The numerical examples demonstrate that the proposed master-slave approach yields better accuracy in enforcing displacement constraints and requires approximately the same computational time as that of penalty method.     

用 Gd2O3 做介质缓冲层制作金属包覆光波导偏振器

首次报道了采用Ｇｄ２Ｏ３薄膜作介质缓冲层制作金属包覆Ｔｉ：ＬｉＮｂＯ３光波导偏振器。通过对理论模型的计算选取合适的介质缓冲层厚度,给出了理论计算和实验结果。测试结果表明,我们实际制作的Ｇｄ２Ｏ３／Ａｌ包覆Ｔｉ：ＬｉＮｂＯ３偏振器的偏振消光比＞３５ｄＢ。     

临近空间飞艇内部自然对流的流场特征仿真

针对临近空间飞艇,对其内部氦气的自然对流特征进行了数值模拟。采用计算流体力学方法,并利用自编的用户自定义函数将外部的温度边界条件导入壁面网格。在不同的稳态条件下,通过对内部氦气压力、温度、速度的分布等流场特征参数的研究,分析了临近空间飞艇内部气体自然对流的运动特性及其影响规律,并对自然对流非稳态变化过程进行了初步的探索。仿真结果表明,在临近空间环境下,飞艇内部氦气的自然对流,对于内部氦气自身的热交换具有一定程度的促进作用,而对蒙皮受力和结构安全性影响很小。