多全球导航卫星系统联合的探月飞行器轨道定位分析

针对探月飞行器月球公转轨道上的卫星导航定位问题,以高轨道飞行器卫星导航定位的研究为基础,采用多全球导航卫星系统联合定位的方法进行仿真。分析了载波功率与噪声功率密度比为15d BHz的弱信号捕获门限下,各系统联合定位时波束主瓣和旁瓣的可用性,同时对各系统联合情况下的精度因子值进行分析。仿真结果表明:当接收到的卫星天线辐射的主瓣和旁瓣信号均高于载噪比门限时,全球导航卫星系统的三系统或四系统的联合能满足实时定位条件;而旁瓣损耗不加以补偿时,接收信号载噪比低于门限并导致任意联合方式均无法完成定位。各系统联合的精度因子分析表明:单系统或双系统联合的几何精度因子变化剧烈,四系统联合相比三系统联合的几何精度因子下降16.93%;三系统联合定位方案中,美国全球定位系统、中国的北斗卫星导航定位系统与欧洲的伽利略卫星导航定位系统联合方案的几何精度因子值变化最平稳,为最佳选择。理论分析和仿真结果为探月飞行器定位技术研究和星载多系统接收机设计提供参考。     

From Rebel to Quasi-State: Governance,Diplomacy and Legitimacy in the Midst of Afghanistan’s Wars (1979–2001)

Abstract

How do warlords build their legitimacy and eventually exert authority? The case of Afghan leader Ahmad Shah Massoud demonstrates that warlords do not only build legitimacy through the internal provision of goods and services to the population under their control, but also build their legitimacy by projecting authority externally, through the development of their own form of diplomacy. In this article, I show that warlords develop complex and complementary legitimisation strategies that extend beyond their territorial realms to include consequential relationships with foreign actors.     

When the military become a security and political threat: Zimbabwean army generals in electoral politics

The military poses an ongoing threat to modern democratic rule in some African countries, especially in the Zimbabwean context. This paper reveals the ways in which Zimbabwe National Army (ZNA) generals have played a political role in the Zimbabwean elections, an issue which is both a political threat and a security threat to the state. It is argued that the ways in which ZNA generals engage in the political process goes against Section 208(2) of the constitution of Zimbabwe, which summarily states that the military must be apolitical. In substantiating this argument, the paper presents and analyses various public speeches made by army generals. It is contended that the army generals’ support of the Zimbabwe African National Union – Patriotic Front (ZANU-PF) and President Robert Mugabe has to be understood as a ‘mutual accommodation’, i.e. the generals are offered privileges in return for the political protection of the ruling regime which negatively impacts the security of the vote.     

Japan’s Emerging Trajectory as a ‘Cyber Power’: From Securitization to Militarization of Cyberspace

Japan has been overlooked as a ‘cyber power’ but it now becoming a serious player in this new strategic domain. Japanese policy-makers have forged a consensus to move cybersecurity to the very core of national security policy, to create more centralized frameworks for cybersecurity, and for Japan’s military institutions to build dynamic cyberdefense capabilities. Japan’s stance has moved rapidly toward the securitization and now militarization of responses to cyber challenges. Japan’s cybersecurity stance has bolstered US–Japan alliance responses to securing all dimensions of the ‘global commons’ and extended its defense perimeter to further deter but potentially raise tensions with China.     

Neural network modeling to evaluate the dynamic flow stress of high strength armor steels under high strain rate compression

An artificial neural network (ANN) constitutive model is developed for high strength armor steel tempered at 500 °C, 600 °C and 650 °C based on high strain rate data generated from split Hopkinson pressure bar (SHPB) experiments. A new neural network configuration consisting of both training and validation is effectively employed to predict flow stress. Tempering temperature, strain rate and strain are considered as inputs, whereas flow stress is taken as output of the neural network. A comparative study on Johnson–Cook (J–C) model and neural network model is performed. It was observed that the developed neural network model could predict flow stress under various strain rates and tempering temperatures. The experimental stress–strain data obtained from high strain rate compression tests using SHPB, over a range of tempering temperatures (500–650 °C), strains (0.05–0.2) and strain rates (1000–5500/s) are employed to formulate J–C model to predict the high strain rate deformation behavior of high strength armor steels. The J-C model and the back-propagation ANN model were developed to predict the high strain rate deformation behavior of high strength armor steel and their predictability is evaluated in terms of correlation coefficient (R) and average absolute relative error (AARE). R and AARE for the J–C model are found to be 0.7461 and 27.624%, respectively, while R and AARE for the ANN model are 0.9995 and 2.58%, respectively. It was observed that the predictions by ANN model are in consistence with the experimental data for all tempering temperatures.     

Initiating insurgencies abroad: French plans to ‘chouannise’ Britain and Ireland, 1793–1798

Secret French plans to launch guerrilla-style raids on the British Isles devised in the spring of 1796 were referred to as ‘chouanneries’. The name and concept behind these small-war operations were modelled on the irregular tactics used by the Chouan rebels in the Vendée, which the French state army had brutally quashed, but some wished to transfer into their institutional practice. Part of France's ongoing military strategy in the war against Britain, which included fomenting insurrection in Ireland, these irregular operations were to be manned partially by pardoned deserters and released convicts and prisoners of war. Of these, only Tate's brief invasion of Wales in 1797 was realised, but the surviving plans provide insightful historical lessons into an Anglophobic mindset shared by a small network of practitioners and policy deciders on the effectiveness of such shock and awe tactics. Largely motivated by the desire to take revenge for Britain's support of counter-revolutionaries in the Vendée, these plans could more aptly be referred to as counter-‘chouanneries’.     

Causal Linkages Between Domestic Terrorism and Economic Growth

We use the Hsiao–Granger method to test for terrorism–growth causality for seven Western European countries. In bivariate settings, the impact of economic performance on domestic terrorism is very strong. In trivariate settings, the impact of performance on terrorism diminishes. In general, we find that economic performance leads terrorist violence in robust ways only for three out of seven countries. Terrorism is almost never found to causally influence growth in bivariate and trivariate specifications. Our findings indicate that the role of economic performance in determining terrorist violence appears to have been important for some countries, whereas all attacked economies have been successful in adjusting to the threat of terrorism.     

A Note on the Economics of Stolen Valor

Abstract

The economics of stolen valor concerns the act of trading on false claims of being awarded valorous military service medals. The U.S. Supreme Court overturned the 2005 Stolen Valor Act, largely on First Amendment grounds. Misrepresentation that devalues the reputation of medals for valor may not violate the revised statute despite decreasing the wage premium and discouraging investment in military effort.     

SECURITY AND FORCED MIGRATION CONCERNS IN SOUTH AFRICA

“As we close this century, there is for the first time realistic hope of a more just future. A Century stained with the sufferings of ceaseless war and atrocity is as much marked by our incomplete efforts to secure the foundations of an international society, one in which all peoples are equal and equally protected from abuse. The last decade has seen the application of dormant humanitarian principles and laws in various fora. The ICC offers us the opportunity to build on these disjointed enforcement efforts. A properly functioning permanent court will be humanity's best chance yet to move out of its self-destructive cycle. Justice is a vindication, a historical right and a deterrent.”