Optimal allocation of minimal repairs in parallel and series systems

In reliability engineering, the concept of minimal repair describes that the repair brings the failed unit (eg, system or component) to the situation which is same as it was just before the failure. With the help of the well‐known Gamma‐Poisson relationship, this paper investigates optimal allocation strategies of minimal repairs for parallel and series systems through implementing stochastic comparisons of various allocation policies in terms of the hazard rate, the reversed hazard rate, and the likelihood ratio orderings. Numerical examples are presented to illustrate these findings as well. These results not only strengthen and generalize some known ones in the seminal work of Shaked and Shanthikumar, but also solve the open problems proposed by Chahkandi et al.'s study and Arriaza et al.'s study.     

Coercive diplomacy and the Donbas: Explaining Russian strategy in Eastern Ukraine

What were Russia’s objectives in Eastern Ukraine, and why was it seemingly unable to achieve a successful or decisive outcome? In contrast to Russia’s seizure of Crimea, the uprising in Eastern Ukraine was marked by disorganization and chaos. Using proxy and surrogate actors, along with military exercises and the injection of Russian troops, Russia sought to institutionalize a political entity inside Ukraine to influence its domestic politics. In this article, I analyze the mechanisms by which Russia attempted to implement, and later salvage, its strategy. The article contributes to clearer theoretical and practical understanding of limited force in coercive diplomacy, signaling, and a more rigorous treatment of the role and uses of proxy actors.     

National restrictions in multinational military operations: A conceptual framework

Recent scholarship in security studies has started to explore the causes and consequences of various forms of national restrictions in multinational military operations (MMOs). This article makes a conceptual contribution to this literature by developing a theoretical framework of national restrictions in MMOs that distinguishes between structural, procedural, and operational restrictions. I argue that these types of restrictions are governed by different causal mechanisms. Structural restrictions are relatively stable over time and effect deployment decisions irrespective of other factors. Procedural restrictions, on the other hand, can constitute veto points against deployment only in combination with distinct political preferences. Finally, operational restrictions directly affect the rules of engagement of troop contributing countries. The article illustrates the three types of restrictions and their interaction with empirical examples from a range of countries and sketches their impact on MMO deployment decisions and mandates.     

Buy now,pay later: American military intervention and the strategic cost paradox

This paper explores the notion that US efforts to evade the political costs of war paradoxically contribute to the subsequent exacerbation of costs over time. Leaders seek to purchase political capital in the short term by limiting the costs and requirements of military operations, but in doing so cause strategic and political liabilities to mount in the long run. While identification of such behaviour is not new, insufficient attention has been devoted to explaining its causes, dynamics, and manifestations in relation to key decisions on and in war. Evidence derived from studies of recent American discretionary campaigns is analysed to advance an argument with respect to this pattern of self-defeating strategic behaviour.     

On the roles of free play in army exercises and the Russians

The article outlines the essential role of free play elements in various types of exercises for the development of in-depth and practical military professionalism. It thereafter argues why such use of free play contradicts the military science founded Russian Way of War.     

Regular and irregular forces in conflict: nineteenth century insurgencies in South America

ABSTRACT

In the decades following independence from Spain, ‘civil wars’ ravaged the newly established polities in South America. Former vice-regal capitals inherited a larger portion of the colonial administration and had larger economic resources and a hegemonic project they were able to have permanent and professional armed forces, capable of leading the offensive and giving battle following the European rules of military art. The central hypothesis of this work is that there is a necessary relationship between the shape of these asymmetrical conflicts, their outcome and the political territorial configuration of each country in post-revolutionary Spanish America. When permanent armies took over from local militias, the capital kept the integrity of its territories and there was a tendency towards political centralization. When this did not happen and the militias managed to find a way to defeat their centralizing enemies, the local powers had an opportunity to renegotiate their participation in the political body, and sought to maintain their independence, which was manifest in federal agreements, otherwise a process of territorial fragmentation began. More than a difference between regular and irregular forces there was one between intermittent, and permanent mobilization.     

阵列雷达自适应多零点单脉冲群目标测角算法

针对阵列体制雷达,由极大似然估计导出自适应多零点单脉冲测角原理。分析发现迭代步长过大导致双零点单脉冲技术在多目标条件下失效,因此提出加权步长改进角度估计的迭代过程,只需要较少计算量就能实现群内多个目标的精确测角。仿真结果表明：该算法在较高信噪比条件下可以精确测量群内三个目标角度,测角误差约为0.15倍波束宽度;当群目标数较多或者目标相位差接近于0时,算法性能下降明显。     

北斗系统新民用导航电文历书参数算法与性能分析

研究新公布的北斗民用导航电文中的两类历书与北斗二号导航电文历书的差异,对比分析各类历书对接收机首次定位时间的影响。利用实际的历书数据,比较不同历书类型的用户算法,分析不同龄期数据对接收机首次定位性能的影响。结果表明,高精度历书在1周的数据龄期内性能较为稳定,中等精度历书精度稍逊于高精度历书,但由于简化了电文空间,能接近高精度历书性能。简约历书进一步简化了参数数目和电文空间,尽管位置误差达到了数百千米,但却能在数月之后保持相应精度,有利于缩短接收机首次定位时间。     

基于两阶段算法的半潜维修船功能舱室布局

以维修舱空间、舱室邻接、舱室全局位置三个指标为目标函数,以满足高初稳性要求、保证船舶浮态等为约束条件,建立技术可行前提下半潜维修船功能舱室布局优化模型。通过设计贪婪取走启发式算法与规划求解相结合的两阶段算法,实现对模型的求解。以载重为5×10~4 t的半潜船体为载体进行设计,得到半潜维修船功能舱室优化布局方案。随着维修设备质量系数的增加,可行的布局方案数呈上升趋势。该方法可提高半潜维修船在功能舱室布局过程中决策的科学性。     

Honour,Comradeship and Betrayal: Lord Capel’s Sword

The sword which is the subject of this article and which will be referred to as the Capel sword, is a fine example of what has become known as an Irish basket-hilt. Whilst there are other examples in existence, what makes this sword unique and particularly important is the fact that it is known to have been owned by two important Royalist military leaders, Lord Arthur Capel and Sir John Owen. These two extraordinary men came from different backgrounds but their fate was linked through circumstances beyond their control. The story this sword tells is one of comradeship, loyalty, total belief in a cause, betrayal and ultimate sacrifice.