军事欺骗的魔力

著名军事理论家克劳塞维茨曾指出：“任何一次作战都离不开诡诈(即使是很小程度的诡诈)。”拿破仑则将军事实力和军事欺骗比喻为狮子皮和狐狸皮,并指出：“在战争中,狐狸皮和狮子皮同样需要,因为当实力弱小时,狡计反能成功。”而当前美军更加重视军事欺骗在战争中的作用,为此专门制定了联合出版物JP3—58号《军事欺骗联合条令》,其中强调：“军事欺骗能误导敌方军事决策者,使之误判我方军事能力、意图和行动,从而造成敌人采取有利于我完成任务的具体行动,这是实现信息优势乃至决策优势的有效途径。”     

政治因素让F-22远离利比亚?

美国在不理会利比亚防空力量的同时就能歼灭卡扎菲的空军。这也就意味着．美国只需要用F-22唱“独角戏”就可以消灭利比亚空军,而无需任何国际合作了0禁飞区所能产生的一个预期效果是为了不让敌人的飞机起飞,然而使用F-22战斗机可以在不消灭敌防空力量的情况下实现这样的效果。但是这样做的结果是排除了其他联盟伙伴参与的可能性,因此从政治上来说不是一个理想的选择。     

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.     

俄海军面临第五次复兴

第二次世界大战后,苏联经过40多年的发展,形成了一只可以和美国在全球争霸的远洋作战海军。苏联解体后．由于俄罗斯经济长期萧条．俄罗斯海军也面临着前所未有的严峻局面。1989年苏联的造船工业共为其海军制造了78艘潜艇、作战舰艇及勤务舰船,而1995、1996、1997年俄罗斯海军分别只有11、8、6艘新造舰艇服役,到了1999年则只有4艘。     

基于稳健统计特征的飞机识别方法

本文介绍了基于统计特征(StaF)的分类器,它是一种稳健的、用于高距离分辨率(HRR)雷达的飞机识别(ID)方法。在对特征的数量或位置不作先验假定的情况下,我们实时地选择HRR图像的峰值特征。特征提取依靠所观测到图像的信息内容,把特征的数量、位置和幅度作为随机变量。本项研究的主要目的是,通过把对未知目标的识别错误减少到最小,同时维持对已知目标的高识别率的方法来增强分类器的稳健性。结果表明,这种StaF分类器能够显著地减少与未知目标有关的识别错误,同时维持高概率的正确分类。     

Mechanical stress and deformation analyses of pressurized cylindrical shells based on a higher-order modeling

In this research, mechanical stress, static strain and deformation analyses of a cylindrical pressure vessel subjected to mechanical loads are presented. The kinematic relations are developed based on higherorder sinusoidal shear deformation theory. Thickness stretching formulation is accounted for more accurate analysis. The total transverse deflection is divided into bending, shear and thickness stretching parts in which the third term is responsible for change of deflection along the thicknes...     

Assessment of the ballistic response of honeycomb sandwich structures subjected to offset and normal impact

In the present study, experimental and numerical investigations were carried out to examine the behavior of sandwich panels with honeycomb cores. The high velocity impact tests were carried out using a compressed air gun. A sharp conical nosed projectile was impacted normally and with some offset distance(20 mm and 40 mm). The deformation, failure mode and energy dissipation characteristics were obtained for both kinds of loading. Moreover, the explicit solver was run in Abaqus to create the fin...