一种极区统一坐标系及其导航参数转换方法

为了实现横向导航体系和格网导航体系的统一,化简不同导航体系的转换关系,提出了一种基于横向坐标系的极区坐标系定义方法,并证明采取本极区坐标系可以在地理极区范围内使横向坐标系的横向经纬线近似构成格林尼治导航格网,从而实现横向地理坐标系与格林尼治格网坐标系的统一,使得格网导航坐标系的建立独立于海图。基于新定义的坐标系进一步定义了统一的极区横向经纬度位置和格网航向等主要导航参数,并给出本极区坐标系与目前常见极区坐标系简捷的转换关系。分别在中低纬度和极区对横向坐标系编排和传统地理坐标系编排的仿真进行对比,验证了提出的横向坐标系的可行性。     

极区极球面投影的可用性及误差分析

为解决墨卡托投影在高纬极区变形过大而不适用的问题,分析了极球面投影的极区投影变形、经纬线形状以及大圆航线与直线的逼近程度,结果表明:极球面投影能够克服墨卡托投影不足,可满足极区海图投影要求;推导了航程及航向误差公式并分析了其变化规律,结果表明:极球面投影上直线代替大圆航线具有可行性,证明了极区极球面投影的可用性。     

基于极球面投影的极区格网坐标表示方法?

随着全球气候变暖，北极冰盖的快速消融使北极航道的夏季全线通航成为可能，但由于极区经线的快速收敛，导致基于地理坐标的传统航海导航方法误差过大而不能使用。针对这一问题引发的极区导航问题进行研究，首先对常用海图及传统航海导航方法在极区使用存在的问题进行分析，然后采用极球面投影下的极区格网坐标表示方法，给出了极球面投影格网坐标与地理坐标的转换关系，该方法能够使在极区航行的船舶便捷、准确地确定其在地球的位置，为极区航海作业提供方便。     

反辐射无人机导航路径规划模型研究

反辐射无人机作为近年来受到世界各国广泛关注的新型信息化武器,其导航路径规划研究也成为了反辐射无人机应用研究领域的热点之一。针对反辐射无人机的导航路径规划问题,在对导航路径规划相关概念进行系统阐述的基础上,重点分析了反辐射无人机导航路径规划航向选择和航行剖面选择的影响因素,提出了航向选择和航行剖面选择约束条件。最后,给出了反辐射无人机导航路径规划的航向选择模型和航行剖面选择模型。     

水下导航系统误差辨识及修正方法

水下航行器经常采用航位推算方式进行定位.由于存在传感器误差,航位推算的定位误差是随着时间发散的,而直接准确检测这类误差非常困难.对航位推算导航系统误差源进行分析与辨识,在此基础上推导出一种新的辨识AUV (Autonomous Underwater Vehicles)导航误差参数的方法,经实航试验结果表明,该算法能够准确辨识AUV导航误差参数向量,简单有效.     

惯导系统极区导航性能仿真分析

极地地区具有纬度高、经线收敛快、存在极点等特点,对惯导系统的测量元件规格要求、数学计算和导航性能产生了较大影响。对此,首先研究了惯导系统导航算法在极区工作存在的问题,然后通过惯导系统静基座误差分析和数字仿真,分析了惯导系统极区导航性能。研究表明:在高纬地区,纬度越高,惯导系统航向与速度误差越大;在近极点区域,惯导系统会出现计算奇异值问题,且各导航参数系统误差均很大,导致丧失导航性能。     

基于位置矢量的大椭圆导航参数计算方法

基于椭球体的大椭圆航行是一种经济可行的远洋航法,为确保船舶沿期望的大椭圆航线航行,提出了一种大椭圆航线导航参数计算方法。该方法采用位置矢量法求解大椭圆顶点,进而定义了长轴矢量和短轴矢量,并在此基础上推导了形式更为紧凑的航向角、航程和偏航距计算公式。算例分析表明:该方法推导的公式计算简洁,可有效解决航海中大椭圆导航的计算问题。     

航路点导航参数计算

根据当前船位和预置的航路点位置计算航路点导航参数是舰船导航的基本问题,为此推导了一组大圆航法和等角航法下航路点导航参数的解析计算公式,非常适合于在组合导航系统中使用。     

大圆航线导航与控制律设计

随着无人机(UAV)应用范围的扩大,要求无人机能精确跟踪预定航线.预定的飞行任务可以有两种规划方式,一是近似在当地切平面上的直线或曲线;二是飞行距离较长时在地球表面的大圆航线.第二种规划相对复杂,研究较少,因此,介绍了某型无人机的动力学模型,提出了一种全新的大圆航线导航解算算法,设计了大圆导航控制律,此外,还分析了常值风及突风干扰对导航的影响.经计算机仿真验证和部分的实际飞行试验结果表明:与预定航线的距离偏差较小,航迹精度较高,新算法及设计较好地满足了实际大圆航线飞行要求.     

GPS双星航姿测量研究

提出用两部测量型GPS接收机 ,实时观测两颗以上GPS卫星在站心坐标系下的高度角、方位角和载波相位 ,来推算基线 (船体 )的航向和姿态 ,初步解决了整周模糊度的解算问题 .文中对影响航向和姿态准确解算的因素进行了分析 ,并提出了改进的办法 .     

An Unlikely Alliance: Portuguese and South African Airpower in Angola, 1968–1974

The war that Portugal was obliged to fight in Africa began in 1961 and immediately stretched the resources of its armed forces. Nowhere was this thinness more apparent than in policing the vast territory of Angola. The east and southeast of Angola were particularly vulnerable, as the area was a vast, sparsely populated region characterised by enormous featureless plains or chanas covered in tall grass and broken by an extensive river system and mountainous forests. The only military solution to policing these immense spaces was aviation and specifically the helicopter that could carry troops into battle, protect them with a gunship and bring them home when the operation was concluded. The immediate problem for the Portuguese Air Force (Força Aérea Portuguesa or FAP) in Angola and elsewhere was a scarcity of helicopters. The solution was an alliance with South Africa, which had a strong inventory of Alouette IIIs, to help in policing the east. This move was likewise in the interest of South Africa, as its threat came from Zambia through south-eastern Angola. This article examines the strategic and tactical development of this unusual, cross-cultural alliance and the symbiotic relationship that resulted in destruction of the enemies of both in Angola.     

国内外结构钢焊条研究的现状与发展

本文主要介绍了国外焊条的现状和发展趋势,包括焊条的高韧性、高效率、低尘低毒和耐吸潮性能,为国内的焊条研究提供了参考依据。     

A Sign of Victory?: ‘Scottish Swords’ and Other Weapons in the Possession of the ‘Auld Innemie’

Many late medieval documents, notably inventories of arms and armour, of Englishmen contain references to ‘Scottish swords’ and other weapons. What did the compilers of these documents mean when they described a weapon as ‘Scottish’? How did such weapons come to be in the possession of these men? This article will attempt to explain this phenomenon drawing on primary documentary sources and surviving material culture from Glasgow Museums’ collections and others, as well as artworks from the period.     

Helping hands: civil–military cooperation and Italy's military operation abroad

In the Post-Bipolar Era the growing complexity of the military operations requires a new approach for the resolution of international crises. Since the end of the Cold War, peace support operations (PSO) have become the mainstay and principal occupation of most Western armies. At the same time, Italy has been one of the most important actors in such an area. The article focuses on the cooperation between military and civil components (a process called CIMIC) as a key variable in the Italian PSOs. We will analyse in detail the main lessons learned from past military interventions as well as the general context in which new tendencies are taking place. The maintaining of a minimum security frame becomes essential to fulfil activities ‘collateral’ to the mission: reconstructing services and infrastructure, food distribution, water and medication, law and order, de-mining, training of local forces, and supporting local institutions. These are the main tasks to obtain thrust and support from the population.     

Terrorism,insurgency, kidnapping,and security in Africa's energy sector

Energy continues to serve as the bedrock of modern economies and the main driver of modern society. For Africa, the production and supply of energy resources such as crude oil, natural gas, uranium, coal, biomass, biofuels and other renewables are an important source of employment, rents, taxes, royalties and profits. This sector brings in several tens of billions of dollars of revenue annually. The production and delivery of such resources, however, depend on critical infrastructures such as pipelines, refineries, processing plants, terminals, rigs, electrical energy pylons, substations, pump stations, vessels, and tankers. These infrastructures have been attacked by terrorists, insurgents, vandals and saboteurs, all of whom see them as targets against which to register their grievances and extract concessions from the state. This paper is a chronological account of some of the documented incidents of terrorism, insurgency, kidnapping, destruction, sabotage, and human casualties suffered in the oil and gas sectors in Africa between 1999 and 2012. It is based on data extracted from the databases of the RAND Database of World Terrorism Incidents and the University of Maryland's Global Terrorism Database (GTD).     

Cyberpower in Strategic Affairs: Neither Unthinkable nor Blessed

Abstract

This article explores the effect of connectivity on strategic affairs. It argues that the effect on war's character is potentially, although not yet shown in practice, considerably large. Its effect upon the distribution of power among states in the international system is small, contrary to the claims of ‘cyberwar’ alarmists. All told, however, its effect upon strategic affairs is complex. On the one hand, it represents a significant advance in the ‘complexification’ of state strategies, understood in the sense of the production of intended effects. On the other hand, strategists today – still predominantly concerned with the conflicts and confrontations of states and organised military power – are generally missing the power which non-traditional strategic actors, better adapted to the network flows of the information age, are beginning to deploy. These new forms of organization and coercion will challenge the status quo.     

Tacit support for terrorism: The rapprochement between the USSR and Palestinian guerrilla organizations following the 1967 war

This article demonstrates the inconsistent and wavering Soviet attitude towards national liberation movements in general and the Palestinian organizations in particular. Until the late 1960s, the Soviets viewed these organizations with suspicion, hesitating to engage in political dialogue with them. However, in the 1970s, political and military events in the region, as well as modifications in the Kremlin's Cold War strategies, led to a general shift towards the Middle East in Soviet foreign policy. Soviet leaders showed increased willingness to provide certain Palestinian organizations with arms with which to conduct terrorist activities against Israeli, pro-Israeli, Jewish and Western targets. The article explores the complex relations between Palestinian organizations and the USSR in the field of international terror. The study also exposes and analyzes the nature and content of Soviet–Palestinian arms dialogues and transactions. It provides clear evidence that Soviet policymakers and other luminaries were fully informed of, and sometimes directly involved in, these transactions and dialogues at the highest levels.     

A1 Qaeda and the radical Islamic challenge to western strategy

The September 11 global crisis prompted by the attacks on the World Trade Center and the Pentagon raises major questions concerning the nature and trajectory of terrorism in the post-Cold War global order. Hitherto, terrorism has been largely debated by analysts at the level of nation states. Terrorist and insurgent movements have also been largely anchored in nationalist and ethnic power bases even when they have sought to mobilise a transnational ideological appeal on religious or class grounds. There have been a few exceptions to this pattern such as the alliance between the German Baader-Meinhof group and the Japanese Red Army Faction, but even such international alliances as this did not, until at least the 1980s, presage anything like a global terrorist network necessitating a global strategic response. This study examines terrorism and global strategic responses.