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.     

分布式多媒体系统的操作系统支持结构

分布式多媒体系统应用在系统的各层次——从网络协议、操作系统到操作应用支持平台——引起了新的设计挑战。本文介绍了一种将网络服务与操作系统综合起来用以支持分布式多媒体系统的面向对象体系结构。该结构称为动态对象结构(DOA),基于开放分布式处理(DOP),是基于分布式系统的客户服务器结构国际标准。DOA利用面向对象技术解决分布式多媒体系统的各项要求,诸如连续媒体、自然同步、服务动态质量(QoS)和分组通信等。该结构还提供一种途径,即应用成熟的工业标准来开发新的应用领域,同时保持与旧的应用领域的兼容性。     

模糊逻辑应用于多传感器多目标相关

一致性战术图象要求数据融合技术把来自不同对象和通常含糊的态势的信息进行组合并传播。信息包含在两种类型的数据中:从传感器测量得到的数值数据,和从操作手以及领域专家得到的语言数据。在实际情况中,数值数据可能是有噪声的、不一致的、不完整的;而语言信息是不确切的、模糊的。为同时处理这两种类型的数据,模糊集和模糊逻辑提供一种方法论,能够为其复杂或不定工程问题及时获得近似的但却一致的战术图像。 本论文介绍了模糊数据融合的功能范例。它包含4个基本组成部分:1)明确因素的模糊化;2)从输入/榆出数字关系和人推导出的模糊知识库;3)基于某种模糊逻辑的模糊推理机构;4)将模糊输出解模糊为明确的输出供工厂使用。对于一个实时的实际系统而言,从给定的明确输入集中给出在线的模糊隶属函数是很重要的。为此,从明确输入数据中估计出最优隶属函数的方法已经实现。这是基于L.A.查德提出的可能性/概率一致论原理。模糊隶属函数和统计输入数据置信度之间的关系已经形成,并用作模糊化的一个设计参数。该技术已应用于二维多传感器多目标跟踪系统。文中还介绍了模糊系统性能评估。利用实验室环境中的仿真数据进行仿真评估使命航空电子技术传感器最佳协同系统MASS。对于使用模糊逻辑技术数据相关函数,显示     

MICOS——挪威皇家海军新型反水雷系统

西姆拉德和汤姆逊——森特拉ASM公司联合研制了“奥克索依”级猎雷艇和“阿尔塔”级扫雷艇的反水雷系统(MCM)。 新型猎雷艇和扫雷艇的最初要求是由挪威皇家海军,根据复杂水域反水雷作战的丰富经验和成就,正式提出的。挪威皇家海军的目的是通过他们的4艘“奥克索依”级猎雷艇和5艘“阿尔塔”级扫雷艇获得最好的反水雷性能价格比并且是有效的工具。     

VR黑板——策划和训练的任务可视化

本文概述了虚拟现实(VR)在临场训练中的优点以及在进行虚拟现实设计中应注意的问题。     

自治舰艇概述

由海军水面战中心(NSWC)的创新中心卡特洛克分部提出的自治舰艇概念阐述了用先进的计算技术在未来舰艇中实现全系统综合、自动化并减少人员配备。该概念综合分布式结构、信息技术和模块化系统,使用4个自治原理:容错系统、软件对象、无处不有的计算以及任务和功能分析。简单地说,自治舰艇的形象可描述为这样一种舰艇,即人们决定做什么,舰艇就做什么。