舰船航渡过程中的松弛时间与航渡策略问题

针对舰船特点和任务要求,提出了舰船航渡中的松弛时间问题。在对问题分析的基础上,给出了松弛时间的定义并对其进行了建模,讨论了航渡失败的判断准则,给出了松弛时间的上下限以及航渡中实际的松弛时间的计算方法,并采用仿真的方法进行了典型航渡过程的松弛时间和成功概率的计算。在大量计算的基础上,初步探讨了航渡成功概率与各类航渡参数之间的关系,并对舰船最优航渡策略问题进行了初步分析,最后对于优化目标、计算初值、结果的表达方式等提出了一个可行的解决方案。     

一类微分方程组极限环的不存在性

在系统奇点唯一的条件下,研究了一类微分方程组不存在极限环的的充分条件,运用和发展了以往的结果。     

战场环境下无人车辆战术机动路径规划方法

针对不同类型威胁体存在的战场环境中无人车辆战术机动路径规划问题,提出了一种基于威胁代价地图的粒子群优化（Particle Swarm Optimization,PSO）方法。借助极坐标系中关键点的极角进行路径描述,并使用分段3次Hermite插值方法形成光滑路径,将路径规划问题转化为关键点极角的参数优化问题。针对基本PSO（BPSO）算法存在的早熟收敛和后期迭代效率低的缺陷,借鉴以群集方式生活的物种按照不同任务对种群进行分工的机制,提出了一种基于多任务子群协同的改进粒子群优化（Particle Swarm Optimization based on the Multi—tasking Subpopu—lation Cooperation,PSO-MSC）算法。借助该算法的快速收敛和全局寻优特性实现了最优路径规划。实验结果表明：该算法可以快速有效地实现战场环境下无人车辆的战术机动路径规划,且规划路径安全、平滑。     

Evaluation of effectiveness of polymer coatings in reducing blast-induced deformation of steel plates

Incorporating elastomers such as polymers in protective structures to withstand high energetic dynamic loads, has gained significant interest. The main objective of this study is to investigate the influence of a Polyurea coating towards the blast-induced response in steel plates. As such, Polyurea coated steel plates were tested under near-field blast loads, produced by the detonation of 1 kg of spherical nitromethane charges, at a standoff distance of 150 mm. Mild steel (XLERPLATE 350) and high-strength steel (BIS80) plates with thicknesses of 10 mm were Polyurea coated with thicknesses of 6 mm and 12 mm on either the front (facing the charge) or the back face. The deformation profiles were measured using 3D scanning. Numerical simulations were performed using the non-linear finite element code LS-DYNA. The strain-dependent behaviour of the steel and Polyurea were represented by Johnson-cook and Money-Rivlin constitutive models, respectively. The numerical models were validated by comparing the plate deflection results obtained from the experiments and were then used in the subsequent parametric study to investigate the optimum thickness of the Polyurea coating. The results indicate that back face coating contributes towards an approximately 20% reduction in the residual deformation as well as the absence of melting of the Polyurea layer, while the front-face coating can be used a means of providing additional standoff distance to the steel plates.     

Becoming a disarmament champion: the Austrian crusade against nuclear weapons

ABSTRACT

The making of the Treaty on the Prohibition of Nuclear Weapons (TPNW) has put Austria and its involvement in nuclear disarmament in the spotlight. This study highlights several factors that led Austria to become a prominent voice in nuclear-disarmament debates. First, its involvement dovetails with the emphasis on humanitarian disarmament it has promoted since the 1990s. Second, a strong antinuclear identity pervades Austrian society. This “nuclear allergy” combines antimilitarism inherited from the Cold War and, more broadly, an aversion to nuclear power, including for energy purposes. These two considerations form the background to the increased activism of the Austrian Foreign Ministry on nuclear disarmament in international fora. But, equally, Austria’s crusade for the TPNW can be attributed to the engagement of a small team of diplomats implementing personal as well as national preferences in favor of disarmament.     

Turning gangsters into allies: the American way of war in Northern Afghanistan

ABSTRACT

The American way of war in Afghanistan presents a conundrum for proponents of 21st-century state-building projects. How can liberal peace proponents engage in efficient state building without sacrificing their ideals? The US learned that state-building allocates a degree of command and control to powerbrokers operating in the shadows to launder aid money, traffic illicit narcotics, and engage in extrajudicial punishments. These clients failed to represent the liberal values foreign patrons endorsed, because the latter not only offered resources without conditions but also rewarded bad behavior. This issue is examined by looking at the case of post-2001 northern Afghanistan, where powerful warlords should have held greater control over their paramilitary forces, limited predatory behavior, and built stronger relationships with the community. Instead, warlords-turned-statesmen expanded their material and social influence in the north, while holding onto the informal instruments of racketeering and patronage that overwhelmed Western ideals and shaped the predatory state present in Afghanistan today. Moreover, paramilitaries were influenced by material, social, and normative incentives that rewarded violent and predatory behavior and further eroded already weak community control mechanisms at the subdistrict level.