基于扩张观测器的三维有限时间收敛导引律

为了保证视线角速率在弹目碰撞前收敛到零附近的较小邻域内从而达到准平行接近的状态,本文基于自抗扰控制的不确定性估计补偿思想,应用反演控制方法设计了一种考虑导弹自动驾驶仪二阶动态特性和目标机动的三维有限时间收敛导引律。根据有限时间收敛控制理论,严格证明了系统的有限时间收敛特性;为抑制量测噪声,将传统跟踪微分器进行改进并应用于扩张状态观测器与反演控制的设计中。仿真结果表明:在自动驾驶仪响应延迟情况下,所设计的导引律能够导引导弹在有限时间内精确地拦截高速机动目标;改进的跟踪微分器精度高、响应快;基于改进跟踪微分器的扩张观测器估计效果理想。     

READY,SET, TRACE

Tracing small arms and light weapons has been identified as an important component in reducing the illicit trafficking of weapons to regions of conflict as well as use in violent crime. At the national, regional and international levels policy makers and practitioners are working to make tracing more effective. This article outlines some of the key elements of an effective tracing regime and reviews where areas of agreement currently exist. It concludes with observations on some of the challenges facing countries as they try to implement these systems and respond to the problem of illicit arms trafficking.     

Drones,spies, terrorists,and second-class citizenship in Pakistan

This essay reviews seven recent books and reports that focus upon the use of US armed drones in Pakistan's Federally Administered Tribal Areas (FATA). This essay synthesizes a historical account of the program, critically interrogates key arguments and evidence advanced by the authors, and draws attention the particular problems that confront those who live in the FATA and the second-class citizenship that the Pakistani state has bestowed upon them for reasons of domestic and foreign policy concerns. This review essay does not intend to be the final word on any of the ongoing policy debates. But it does hope to enable a wider audience to take part in these important deliberations.     

Consumer drone evolutions: trends,spaces, temporalities,threats

ABSTRACT

While the drone has become synonymous with the War on Terror, the asymmetric iconography of the battlefield is shifting. Commercially available off-the-shelf (COTS) drones are increasingly prevalent features of global battlefields, employed by non-state actors in both visualising such spaces, and the directing and inflicting of harm. As such usage increases, so too do concerns around their evolving adoption, adaptation, and potential portability into homeland spheres. While cognizant of the range of positive drone applications, it is asserted that drones nonetheless remain simultaneously bound to an inverse potential for exploitation. In examining drone risk, this article approaches the consumer drone through a series of sites and spaces through which it is technically and socially constructed. Reflecting upon industry innovation, community-driven experimentation, and evolving airspace – it calls for greater attention to the drone’s malleability, arguing that understandings of COTS drones must remain attentive to both drone potential and potential drone threat.     

COOPERATION,SIGNALS, AND SANCTIONS

This paper uses game theory and modeling to address the role of incentive structures and information dynamics in nuclear inspections. The traditional argument is that compliant states should be willing to allow inspections to prove their innocence, while proliferating states are likely to impede inspections. This argument does not take into account the historical variation in inspection, signaling, and sanctioning behaviors. Using a game theoretic analysis and model, it is shown that the separation of proliferators from nonproliferators only occurs when the likelihood of proliferation is high and punishment costs are moderate. The model assumes that states can choose how much to cooperate with inspectors and must pay opportunity or secrecy costs when inspections are effective. The results are tested against a set of real-life cases, providing support for the claims of historical variation and the model's deductive propositions.     

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).     

效率、公平与公共政策

效率是社会经济发展的重要保证,而公平是衡量人类文明的重要尺度,是维护社会稳定的价值基础。效率与公平是辩证的对立统一,既有矛盾性又有统一性。公共政策的关键就是要协调与整合二者之间的关系,确保既能提高经济效率,又能实现社会公平——借助市场机制达到资源的有效配置,以提高效率;依靠社会主义制度解决财富分配不公,以彰显公平。将效率与公平完美地结合于公共政策之中,是社会主义优越性的充分体现。     

Recruiters,advertising, and navy enlistments

Regression analysis is used to estimate the effects on Navy enlistments of recruiters, advertising, unemployment and other factors. In measuring the effects of these factors on enlistments, changes in both the demand for and supply of enlistments are taken into account. Advertising is treated as a capital investment; its effect is estimated using a maximum likelihood technique that was developed for measuring the effects of capital investments. We find strong evidence that recruiters and unemployment increase enlistments. Advertising also seems to increase enlistments, but its effect is highly uncertain. The results suggest that increases in recruiting resources would have eliminated the enlistment shortfalls experienced by the Navy in FY 1978–79.     

VERIFIABILITY,RELIABILITY, AND NATIONAL SECURITY

The rejection of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) by the U.S. Senate in October 1999 could have been avoided, and the consequences of that vote still loom in the minds of supporters of the treaty. President Barack Obama has embraced the vision of a world free of nuclear weapons, and a key element of the Obama administration's arms control agenda is delivering on U.S. CTBT ratification. In order to secure the two-thirds majority in the Senate necessary to ratify the treaty, senators that remain skeptical of nuclear disarmament must also be convinced that the entry into force of the CTBT is in the national security interest of the United States. This article provides an analysis of the issues surrounding U.S. CTBT ratification divided into three segments—verifiability of the treaty, reliability of the U.S. stockpile, and the treaty's impact on U.S. national security—and concludes that CTBT ratification serves the security objectives of the United States. The CTBT constitutes an integral component of the multilateral nonproliferation architecture designed to prevent the proliferation of nuclear weapons, and it constrains the qualitative development of nuclear weapons, thereby hindering efforts by states of concern to develop advanced nuclear weapons.     

North Korea,deterrence, and engagement

The Democratic People's Republic of Korea (DPRK) justifies its nuclear weapon arsenal with the concept of deterrence. It means that it will try to miniaturize and modernize its warheads and missiles. This leads to a first-use doctrine of nuclear weapons. Obama's policy of engagement does not offer a solution to the North Korean nuclear issue as yet. In the context of its policy of critical engagement with the DPRK, the European Union has three key interests: regional peace and stability, denuclearization, and human rights. The Conference on Security and Cooperation (CSCE) could be a precedent. The CSCE process was based on three “baskets”: security, economics, and humanitarian. The multilateral Trans-Pacific Partnership is a step in this regard. This article looks at three theoretical approaches: realism, liberal institutionalism, and liberal internationalism. It concludes that a political strategy to create a stable North Korean peninsula has to go beyond nuclear deterrence that is based on the realist notion of balance of power.     

Ethnicity,class, and civil war: the role of hierarchy,segmentation, and cross-cutting cleavages

Why are some countries prone to ethno-nationalist conflict, whereas others are plagued by class conflict? This is a question that has seldom been raised and rarely been examined empirically. This paper presents a social-structural theory to account for the variable incidence of these two forms of political instability. These two types of conflict result from distinct principles of group solidarity – ethnicity and class – and since each individual is simultaneously a member of an ethnic group (or many such groups) and a particular class, these two principles vary in the degree to which they are mutually exclusive or cross-cutting. The degree of economic stratification between groups and economic segmentation within them shapes the relative salience of each principle of group solidarity in any society and is associated with a characteristic form of political mobilization. In places where between-group inequalities are high, and within-group inequalities low, ethnicity should be the dominant principle of group solidarity and serve as the primary basis of group conflict. By contrast, in countries where between-group inequalities are low, and within-group inequalities high, class is more likely to serve as the dominant principle of group solidarity, and conflicts along class lines are more likely. We test these conjectures with data in over 100 countries on cross-cutting cleavages, ethnic war, and class conflict. The results are supportive of the theory, and provide evidence that how groups are stratified and segmented in societies shapes the type of civil war.     

Mediation in Syria: initiatives,strategies, and obstacles, 2011–2016

This article investigates mediation efforts in Syria from the outbreak of the civil war in 2011 through the spring of 2016. It describes the principal initiatives, analyses differences and similarities across mediators, and identifies strategic obstacles that prevented substantive progress. Focusing on mediation initiatives undertaken by the Arab League and the United Nations, it finds that there is considerable path dependence across efforts and that most of the limited achievements, notably ceasefires in 2012 and 2016, resulted from the application of external leverage. Settlement in Syria was conditioned on overcoming significant commitment problems, aggravated by sectarian mistrust, the fractured nature of the opposition, and international disunity. The article contributes the first review of mediation in Syria that comprehends the conflict in its entirety, systematizes data for research on conflict management, and evaluates existing mediation policy in Syria with an eye to the future.     

坦克火力系统通用技术状态指标体系构建

我军对某型坦克火力系统实施状态维修,准确的技术状态评估是状态维修的前提,技术状态指标体系是进行火力系统状态评估的依据。构建指标体系的过程中,首先应用层次分析法构建技术状态参数体系的层次结构,然后采用云模型的方法获取参数体系中各定性、定量参数的相对重要度等级,依此使参数体系最优化。实例证明,上述方法有效解决了构建坦克火力系统技术状态指标体系的构建中分类不明确、筛选困难等问题。     

Minimax trees,paths, and cut sets

The notions of minimax paths, trees, and cut sets are defined for undirected graphs; and relationships between these entities are established. Simple solution procedures based on these relationships are presented.