线-面传输线Taylor与Agrawal模型解的比较

基于Maxwell方程推导描述外电磁场对导线的耦合传输线模型有Taylor,Agrawal和Rachidi三种模型,每个耦合公式给出相同的传输线响应,但是它们之间又有细微的差别,Nucci和Rachidi通过数值方法验证在圆柱形雷电电磁场激励下这三种线-面传输线模型在负载终端具有相同的全电压解。本文采用解析的方法对线-面传输线Taylor模型和Agrawal模型进行研究,获得了这两个模型基于平面电磁波激励下的终端负载响应的解析解,证明了它们的解析解是相同的。也就是说,线-面传输线Taylor模型和Agrawal模型其实是对同一个解的不同描述。因此,在实际应用时,可以根据具体情况来选择不同的传输线模型进行求解。     

磁绝缘传输线阴极准直建模与仿真

大型脉冲功率装置的磁绝缘传输线(Magnetically Insulated Transmission Line,MITL)阴极长度可达十余米,在悬臂结构下由于重力引起的末端挠度变形将达数厘米.如果不进行准直,由此造成的阴阳极间隙误差可能引起较明显的电流损失.借鉴HermesⅢ装置基于倾斜垫片的直线度调节方案,设计了用...     

Building the Somali National Army: Anatomy of a failure, 2008–2018

ABSTRACT

Over a decade of security force assistance (SFA) initiatives to build an effective Somali National Army (SNA) failed because of the interrelated effects of political, contextual and operational challenges. The key political challenges were interest asymmetry between international actors and Somali elites, insufficient focus on institution-building and a lack of donor coordination. The principal contextual challenges in Somalia were the legacies of two decades of state collapse and the negative effects of clan dynamics. The main operational challenges were building an army while simultaneously fighting a war, the complexities of military integration, and the severe capability gaps afflicting the SNA.