一种离散描述器系统状态调节的反馈控制律

本文探讨了形如 Ex_(k+1)=Ax_k+Bu_k 的定常离散描述器系统的状态调节问题,得出了一个用至多 n 步使描述器从状态 x_0到达原点的闭环反馈控制律μ_k=Kx_k。     

The impact of Islamic State’s ideological correction initiative on al Qaeda’s bid for relevance

ABSTRACT

Al Qaeda following 9-11 experienced a period of stagnation which it sought to remedy through a project of re-branding. Critical of this approach, Islamic State claimed that al Qaeda was an elitist organization that had facilitated the stagnation of the Salafi Jihadist project. In an attempted to claim dominance over the jihad, Islamic State’s endeavored to discredit al Qaeda through a process it presented as ideological correction, linked to Islamic eschatology, sectarian agitation, permissive violence, and the caliphate. Following Islamic State’s acquisition of vast territory in Iraq and Syria, arguments proliferated that Islamic State had surpassed al Qaeda. As the caliphate has collapsed what effects will this have on al Qaeda’s fortunes and strategy? It is argued that Islamic State has provided al Qaeda’s strategic approach with renewed vigour to help ensure its survival and pursue resurgence. Al Qaeda acting in concert with the meta-strategy for survival concept, has altered an existential threat into an advantage through disavowing Islamic State’s methods, continuing to engage with localism, and pursuing rebranding by positioning itself as a moderate alternative. The cases of al Qaeda affiliates in Yemen, Syria, West Africa, and South Asia are instructive in assessing the effectiveness of al Qaeda’s resurgence.     

‘Today we shall drink blood’: internal unrest in Nigeria

Despite some tentative internal peace agreements, Nigeria continues to face violence from multiple groups. This violence feeds upon itself, with segments of the population being mobilized both for self defense and for pressing their ideological and practical goals. These multiple sources of violence, which the Nigerian government appears unable to control to any significant degree, have a long term corrosive effect on the country's internal stability. There are few reasons to be sanguine as to any rapid changes to the level of overall violence or the relative number of armed groups, although their specific identities may shift. Nigeria represents a good case study of a country in which relatively low but persistent violence by a multiplicity of groups can have major impacts on internal security.     

Recursive weighted least squares estimation algorithm based on minimum model error principle

Kalman filter is commonly used in data filtering and parameters estimation of nonlinear system,such as projectile's trajectory estimation and control.While there is a drawback that the prior error covariance matrix and filter parameters are difficult to be determined,which may result in filtering divergence.As to the problem that the accuracy of state estimation for nonlinear ballistic model strongly depends on its mathematical model,we improve the weighted least squares method(WLSM)with minimum model error principle.Invariant embedding method is adopted to solve the cost function including the model error.With the knowledge of measurement data and measurement error covariance matrix,we use gradient descent algorithm to determine the weighting matrix of model error.The uncertainty and linearization error of model are recursively estimated by the proposed method,thus achieving an online filtering estimation of the observations.Simulation results indicate that the proposed recursive esti-mation algorithm is insensitive to initial conditions and of good robustness.     

Understanding the Legitimacy of Armed Groups: A Relational Perspective

Abstract

This paper analyses the multiple pathways through which legitimacy of armed groups is constructed in conflict-affected states. It adopts a political sociological approach to the study of armed group legitimacy. Such a strategy assists in identifying whether armed groups enjoy legitimacy in a given empirical context and avoids applying pre-determined normative criteria. The focus is on three types of relationships: civilian communities, the state or regime in power and external actors including regional and international sponsors, to discern which types of legitimacy matter for armed groups in different relationships.     

Resistance through Islamic clerics against Boko Haram in northern Nigeria

Islamic clerics and scholars constitute one of the community actors affected by the Boko Haram crisis in northern Nigeria. This group is also one that is most familiar with the essential doctrinal elements required to deconstruct the narrative pushed by Boko Haram in a crisis where ideology represents a vital aspect. While not undermining the bearing which socio-economic and political issues have on the crisis, this paper frames the focus to emphasise the long-term battle where Islamic clerics are involved in winning hearts and minds. Drawing upon fieldwork conducted in Sokoto State and Borno State, this paper highlights the influential role of clerics in communal mobilisation and resistance against Boko Haram. It is suggested that a deeper integration of this community actor into the broader counter-insurgency struggle in northern Nigeria would be beneficial.     

基于状态空间模型的航天器装配角偏误差研究

装配过程的误差建模是分析装配误差的重要手段之一。通过分析影响航天器装配结果的尺寸和形位误差、装夹定位误差,将其装配的偏差源分为夹具装夹误差和舱段制造误差两类。并将不同形式的误差通过虚拟夹具的概念进行了统一的表达,进而基于误差流理论针对航天器舱段建立其误差传播的状态空间模型,求出了该过程的状态空间表达式,应用该模型对装配过程中的角偏误差进行了分析。将分析得到的结果同蒙特卡洛仿真的结果进行了比较,两种方法的相对误差小于3%,说明了该方法的可行性。该方法的优势在于它不仅可以分析复杂装配过程,还可以对各工位的装配效果进行观测,从而进行向后分析。     

新疆伊斯兰教建筑装饰艺术的特征

新疆伊斯兰教建筑装饰艺术的特征是以一种特殊的造型、形式、色彩、材质,多种多样的装饰技巧以及独有的审美特征体现出来的。是新疆伊斯兰教建筑文化体系中取得最高成就的一部分,是集实用功能、审美功能、认识教育功能于一体的艺术形式,蕴涵着地域环境、民情风俗、审美价值等丰富的内容,呈现出浓郁的风格特点。这些装饰艺术的特征,影响着人们的情绪,净化着穆斯林们的心灵,给观赏者以建筑装饰艺术的造型、色彩、纹饰的美感,获得审美的愉悦。     

用状态空间法设计低灵敏度 SCFs 的研究

本文从双端接阻无源梯形结构出发,通过两次必要的换标,导出了一种新的完善的 SCFs 的状态空间综合方法。所得到的 SCFs 的状态空间矩阵集的一般形式具有低灵敏度,并且在特定频率下具有零灵敏度。     

基于状态变换的同步时序电路测试生成

详细分析了固定故障所反映出的状态变换特征,提出状态变换故障模型以及相对应的测试生成压缩方法;基于无复位时序电路,深入研究了有复位状态的同步状态机测试生成方法的扩展问题;最后讨论了故障精简以及启发知识在测试生成中的应用问题。