混合现实技术在军事训练中的应用优势——以美军综合训练环境为例

随着科技手段的进步,现代战争的作战样式不断发展。信息化条件下的作战对军事训练提出了更高要求,传统的训练方法与模式亟待改进。混合现实技术的应用开辟了军事训练新模式。这种针对数据的可视化集成运用以及在其基础上开发的训练系统,通过对数据的处理利用实现了军事训练效果的有效评估。本文以美国陆军综合训练环境这一混合现实技术在军事训练中的典型应用案例作为对象,分析概述了综合训练环境的世界地形、训练模拟软件及训练管理工具三大组成部分的功能特点、架构组成,并根据混合现实技术的发展状况探析综合训练环境的应用优势,以期为军队混合现实技术在军事训练中的应用提供一定借鉴。     

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.     

Impact of atmospheric turbulence on coherent beam combining for laser weapon systems

The performance of a laser weapon system based on coherent beam combining (CBC) depends on its propagation properties in the atmosphere. In this study, an analytical model based on partial coherent beam combining (PCBC) for assumed coherence coefficients between beams in a CBC lattice was developed. The Kolmogorov model of atmospheric turbulence and the Hufnagel-Valley model of Cn2 dependence on atmospheric parameters were implemented. Novel simplified metrics were proposed to assess the CBC performance. Several beam profiles (super-Gaussian, truncated Gaussian, etc.) and ge-ometries were analyzed in terms of maximal intensity in the far field. An approximate formula for PCBC efficiency dependent on the Fried radius was proposed. The results of CBC modeling were compared to those of the Gaussian beam propagation model in a turbulent atmosphere. The dependence of CBC performance on the Cn2 parameter, range, and elevation angle was analyzed. It could be concluded that the application of CBC for medium and long range propagation is impractical without an effective adaptive optics system.     

航空集群机载网络Failure-Oblivious路由策略

航空集群机载网络作为集群成员间信息交互的纽带,其路由策略性能优劣直接影响信息传输实时性与可靠性,从而制约网络化集群作战效能发挥.考虑到航空集群机载网络具有诸多不确定性,为应对路由失效以及尽可能避免路由更新,从路由选择算法的角度,在软件定义网络架构下提出Failure-Oblivious路由策略.与传统路由策略不同的是,...     

Skewness correction X̄ and R charts for skewed distributions

This paper proposes a skewness correction (SC) method for constructing the and R control charts for skewed process distributions. Their asymmetric control limits (about the central line) are based on the degree of skewness estimated from the subgroups, and no parameter assumptions are made on the form of process distribution. These charts are simply adjustments of the conventional Shewhart control charts. Moreover, the chart is almost the same as the Shewhart chart if the process distribution is known to be symmetrical. The new charts are compared with the Shewhart charts and weighted variance (WV) control charts. When the process distribution is in some neighborhood of Weibull, lognormal, Burr or binomial family, simulation shows that the SC control charts have Type I risk (i.e., probability of a false alarm) closer to 0.27% of the normal case. Even in the case where the process distribution is exponential with known mean, not only the control limits and Type I risk, but also the Type II risk of the SC charts are closer to those of the exact and R charts than those of the WV and Shewhart charts. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 555–573, 2003     

Formulations for dynamic lot sizing with service levels

In this article, we study deterministic dynamic lot‐sizing problems with a service‐level constraint on the total number of periods in which backlogs can occur over a finite planning horizon. We give a natural mixed integer programming formulation for the single item problem (LS‐SL‐I) and study the structure of its solution. We show that an optimal solution to this problem can be found in \begin{align*}\mathcal O(n^2\kappa)\end{align*} time, where n is the planning horizon and \begin{align*}\kappa=\mathcal O(n)\end{align*} is the maximum number of periods in which demand can be backlogged. Using the proposed shortest path algorithms, we develop alternative tight extended formulations for LS‐SL‐I and one of its relaxations, which we refer to as uncapacitated lot sizing with setups for stocks and backlogs. {We show that this relaxation also appears as a substructure in a lot‐sizing problem which limits the total amount of a period's demand met from a later period, across all periods.} We report computational results that compare the natural and extended formulations on multi‐item service‐level constrained instances. © 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013     

‘Taylor must go’ – the strategy of the Liberians United for Reconciliation and Democracy

In 1999, rebels rose to oppose the newly elected former warlord Charles Taylor in Liberia. Motivated by a variety of reasons, the minimal common denominator of these rebels, who assumed the name Liberians United for Reconciliation and Democracy (LURD), was that Charles Taylor must leave the country. The decentralized nature of LURD though stands out in their struggle, as they don't fit the unitary actor assumed by literature on strategy, nor the alternative conception of decentralized forces fighting for purely local reasons. Understanding such aberrations as LURD is the first step to finding strategies that can incorporate and manage them.     

An alliance between Cyprus and Greece: assessing its partners’ relative security contribution

The issue that this paper tackles is the assessment of the relative security benefits that Cyprus and Greece derive in the context of their cooperation on defence matters. This form of cooperation, known as the ‘Integrated Defence Space Doctrine’, aims at defending their interests in the Aegean Sea and the broader East Mediterranean theatre. The paper relies heavily on earlier research on this topic, which deals with the Greek–Cypriot alliance facing an arms race against Turkey, and uses a coefficient especially designed to assess the optimal levels of security and the associated defence expenditure of the two allies. A comparison of the relative security coefficient values for the two allies suggests that the security benefit that Greece derives thanks to its alliance with Cyprus exceeds the corresponding Cypriot benefit by far. Given the importance assigned to human resources by this index, in conjunction with the demographic problems of Greece, this conclusion justifies the recent Greek defence policy revision, emphasizing quality, capital equipment and flexibility of forces. This revision aims at satisfying the security requirements of the alliance and the increasing demands of an arms race against Turkey.     

CONTRIBUTORS

Russia holds the largest stocks of civilian highly enriched uranium (HEU) of any country, operating more than fifty research reactors, pulsed reactors, and critical assemblies using HEU, as well as nine HEU-fueled icebreakers. Russia's participation in international efforts to phase out civilian HEU is crucial if international HEU minimization efforts are to succeed. Individual Russian institutes and organizations participate in international programs to replace HEU with low-enriched uranium in Soviet-supplied research reactors, develop alternative fuels, and repatriate fresh and spent HEU fuel from third countries. However, an overarching national policy on HEU phase-out has yet to be adopted. There are many obstacles to obtaining such a commitment from Moscow. At the same time, the ongoing reform of the Russian nuclear industry and plans for expansion of domestic nuclear power generation and for increased nuclear exports create opportunities for securing such a commitment.     

THE NEXUS OF GLOBALIZATION AND NEXT-GENERATION NONPROLIFERATION

Although globalization has created opportunities for nuclear and biological proliferation dangers to take root and grow, it also has opened the door to new solutions. Original ideas and approaches are needed to develop a stronger, more flexible next-generation nonproliferation strategy that accounts for the increasingly important integration of economic, political, and technological issues. The foundation of this strategy should focus on tapping the power of market-based mechanisms, understanding how commercially driven decisions affect proliferation threats, establishing new partnerships, and forging cohesion among the current nonproliferation mechanisms. The implementation of such a strategy will require forceful leadership, a cultural shift from both policymakers and the range of stakeholders, and consensus building within the international community.