反卫星武器:增长中的危险

反卫星武器的任务是,摧毁敌方武装力量的指挥控制系统和情报搜集网。这就提出一个非常重要的问题:反卫星武器的军事应用是否会加剧危机和冲突?当世界从和平时期通过危机而走向战争时,反卫星武器的任务将发生明显变化。在谈判解决危机和建立信任的过程中,卫星能为军事当局“突时”传递信息。如果外交遭到失败,同样的信息就可用之于最佳的进攻。卫星还可提供早期预警:在平时有利于消除疑虑,战时则有助于对敌方目标进行报复性打击。     

以微处理机为基础的跟踪与瞄准系统的宽频带现代控制

本文叙述多年来从事宽频带、高精度跟踪与武器瞄准控制系统开发、以至实际实现具有现代技术水平的现代控制理论与微处理机相结合的武器控制系统的一些最新研究成果。     

反弹道式导弹最佳制导规律的确定

当弹道式再入飞行器的状态不确定时,防御弹道式再入飞行器的基本问题之一是制导拦截器问题。一般方法是先使用某种形式的卡尔曼滤波器估算再入飞行器的现时状态,然后预测它的作为时间函数的未来状态。如果知道再入飞行器的性能,就能够算出拦截器的发射时间和发射角,根据这些数据确定标称拦截点.一旦拦截器处于飞行中,由雷达测量结果,就     

船用锅炉鳍片式经济器的传热

烧液体燃料负荷变化范围大的船用蒸汽锅炉,其鳍片式经济器按陆用锅炉机组整理的标准方法进行计算是不能完全反映出船用的特点的。在标准方法中没有引出热有效系数和烟气流速的关系式,而这对船用锅炉工作条件是必须考虑的。提出按折算的给热系数进行传热计算,这在烧重油的条件下确定这一折算的给热系数有困难,因为缺乏对选择一系列系数,其中包括沾污系数的详细介绍。所有这些使计算复杂化,而且降低其准确性。为了使计算方法精确,曾对装鳍片式经济器的船用锅     

在空气中重复脉冲CO_2激光辐照下的金属靶吸收能力的研究

本文研究了空气击穿形成的等离子体和金属靶表面氧化反应对金属有效吸收能力温度曲线的影响。揭示了以重复脉冲CO_2激光在接近铜靶处照射在靶加热情况下空气击穿阈值的降低。对在空气中以连续的和重复脉冲CO_2激光辐照金属加热动力学进行了比较。     

美海军推出直升机部队重组计划

为进一步增强舰载直升机部队的战斗力,美国海军最近制订了重组其舰载直升机队伍的计划。这份由美海军作战部长办公室起草并计划在未来12年内付诸实施的名为“直升机部队发展总计划”(HelicopterMasterPlan)的方案目标是将其舰载直升机中队的数量从目前的25个增加到31个,但舰载直升机中队的类型却从现有的三种减少到两种。根据“直升机部队发展总计划”的要求,美海军直升机部队兵力结构将实行完全重组,新组建直升机海上战斗中队HSC,主要担负诸如后勤保障、扫雷以及作战搜寻和救援等任务。新组建直升机海上打击中队HSM其首要任务是发动反…     

Noise and vibration measurements in a Viking military vehicle

Noise and whole-body vibration measurements were made in a Viking military vehicle to determine the variation that should be expected during repeat measures, the effect of speed (up to 60 km/h in 5 km/h increments), and during travel over different types of terrain (comprising concrete road, gravel track and rough cross-country). Measurements were made at various crew positions (including the driver and commander) in both the front and the rear cabs in the vehicles. Three translational axes of vibration were measured in each seat. Two speeds were investigated over road (35 km/h and 55–60 km/h) and gravel (20 km/h and 35 km/h) surfaces. The effect of varying speed of the vehicle on the measured noise and vibration magnitudes was also investigated. The highest sound pressure level (L_Aeq) of 104 dB(A) was measured at the commander’s standing position during travel over concrete road at 55 km/h. Higher noise levels occurred for a standing commander compared with when sitting on the seat. A maximum single axis frequency-weighted vibration magnitude of 1.0 m/s² r.m.s. was measured on the driver’s seat during travel over track at 35 km/h. Higher vibration magnitudes occurred during travel over track compared with travel over road. Both noise and vibration exposure of crew within the Viking vehicle increased with increasing speed of the vehicle.     

Influence of porosity distribution on nonlinear free vibration and transient responses of porous functionally graded skew plates

This article deals with the investigation of the effects of porosity distributions on nonlinear free vibration and transient analysis of porous functionally graded skew (PFGS) plates. The effective material properties of the PFGS plates are obtained from the modified power-law equations in which gradation varies through the thickness of the PFGS plate. A nonlinear finite element (FE) formulation for the overall PFGS plate is derived by adopting first-order shear deformation theory (FSDT) in conjunction with von Karman’s nonlinear strain displacement relations. The governing equations of the PFGS plate are derived using the principle of virtual work. The direct iterative method and Newmark’s integration technique are espoused to solve nonlinear mathematical relations. The influences of the porosity distributions and porosity parameter indices on the nonlinear frequency responses of the PFGS plate for different skew angles are studied in various parameters. The effects of volume fraction grading index and skew angle on the plate’s nonlinear dynamic responses for various porosity distributions are illustrated in detail.     

Critical interfaces in body armour systems

The ballistic performance, and behaviour, of an armour system is governed by two major sets of variables, geometrical and material. Of these, the consistency of performance, especially against small arms ammunition, will depend upon the consistency of the properties of the constituent materials. In a body armour system for example, fibre diameter, areal density of woven fabric, and bulk density of ceramic are examples of critical parameters and monitoring such parameters will form the backbone of associated quality control procedures. What is often overlooked, because it can fall into the User’s domain, are the interfaces that exist between the various products; the carrier, the Soft Armour Insert (SAI), and the one or two hard armour plates (HAP1 and HAP2). This is especially true if the various products are sourced from different suppliers.There are between 30 and 150 individual layers within a typical body armour system, and each of the interfaces between each of those layers will, in some way or another, contribute to the ballistic performance of the system. For example, consider the following interfaces/interlayers: (i) the frictional, sliding, inter-ply surfaces within a soft armour pack, and also between the pack and the carrier, (ii) the air-gaps that may develop within the soft armour pack, (iii) the interconnecting space between the soft armour pack and the hard armour plate, (iv) the nature of the interfaces between adjacent plies of a multiplied backing laminate, even in a highly compressed Ultra High Molecular Weight Polyethylene (UHMWPE) variant, (v) the interlayer between the ceramic and its substrate, within a HAP, and (vi) the geometrical fit between two hard armour plates within a stacked body armour system. This paper will provide a User-friendly overview of all such interfaces and provide unique guidance as to their criticality and influence.