用坐标空间重正化群(PSRG)方法求解二维正方格子铁磁系统的临界指数

本文采用坐标空间重正化群方法(PSRG),对二维正方形点阵最近邻伊辛模型铁磁系统,求解了五个自旋组成块体的临界指数,在块体哈密顿量中保留到的量级。将本文结果与伊辛模型严格计算的理论值、各种临界指数的实验值、以及二维三角点阵三个自旋组成块体的临界指数计算值相比较,可以看到,本文的计算结果均比三角点阵三自旋组成块体的计算值有所改进。     

Lorentz序列空间的一致非方

当p>1时,d(w,p)一致非方的充分必要条件是,从而得到了一致非方与一致凸等价。     

面向GPU的非结构网格有限体积计算流体力学的图染色方法优化

采用图染色方法解决通量累加和局部最大压力计算引起的两种典型资源竞争问题,并通过共享内存的使用、体编号和面编号的重排、面数据的重排三种策略优化图染色方法。针对应用在空气动力学多种规模的三维网格,分别采用双精度和单精度操作数,在Nvidia Tesla V100和K80 GPU上,展开性能测试。结果表明:共享内存的优化效果不明显;体编号和面编号重排降低了图染色方法的计算性能;面数据重排可以有效地优化图染色方法;计算性能在V100上提高20%左右,在K80上提高15%左右。     

空间飞网系统牵拉模式影响研究

针对空间飞网系统任务设计需求,研究飞网牵拉模式对系统展开性能的影响。建立空间飞网系统拉出展开过程动力学模型,并通过地面试验对比验证了模型的有效性。面向任务需求建立空间飞网系统评价指标,针对四、六点牵拉模式,采用有限绳段方法对飞网系统进行建模仿真。模型中保持绳网质量和初始发射能量一致,对评价指标的分析结果表明,在六点牵拉模式下,飞网系统飞行性能指标和力学性能指标有明显提高,但能量利用率和系统可靠性小幅下降。     

Budget allocation,national security,military intelligence,and human capital: a dynamic model

This study develops a dynamic model that integrates military intelligence into the defense capability of the country and the optimal allocation of its government budget. We assert that the effectiveness of the country’s military intelligence is contingent on the quality of its human capital, which, in turn, implies a long-term positive relationship between the government’s various civilian expenditures and its capacity to achieve a cost-effective intelligence and, hence, military capability. This relationship is developed within a multiple-period arms race model between two rivals. Using this model and stylized data for the Israeli–Syrian arms race, we show that an appropriate budget shift from defense to civilian expenditures during the initial periods of the planning horizon will gradually (over a decade, say) increase the quality of human capital in the country and, thus, the effectiveness of its intelligence, which, in turn, will increase the country’s future security and welfare.     

二次检测立方攻击改进与实现

对二次检测立方攻击预处理阶段的提取二次表达式的算法进行了改进以优化攻击效率。将秘密变量的变化引入攻击中,使得攻击模型更加灵活;同时,利用时空折中的思想,通过存储常数项和一次项的计算结果,有效降低二次项的计算量。将改进的方法应用于简化版的PRESENT算法和Trivium算法上,攻击效率有显著提高。     

The Obama administration's phased-adaptive architecture: technological,operational and political issues

In 2009, the Obama administration announced a new missile defense strategy, termed a phased-adaptive architecture (PAA) focused primarily on countering the growing threat from theater ballistic missiles. The success of this strategy is predicated on the rapid development and fielding of successive increments of defensive capability in a manner adapted to the specific requirements for missile defenses in different regions of the world. The administration is committed to building a European regional missile defense system, the European PAA or EPAA between now and 2020. The first elements of the EPAA were deployed in late 2011. However, much progress is still required in order to reach the goals set for the PAA. This article addresses the technological, operational and political issues confronting the Obama administration in its efforts to make the PAA a reality.     

建模仿真主计划及其关键技术

综述了建模仿真主计划 (MSMP)的目的和内容 ,着重阐述该计划中的公共技术框架 ,分析该计划对军事领域内建模仿真活动的影响 ,并对其中某些关键技术问题提出了解决思路或方法     

远程导弹飞行管道碎片数目统计方法研究

摘 要：针对空间碎片数及分布,根据远程导弹飞行散布统计规律,提出一种统计导弹飞行管道内碎片数目的方法,即利用空间碎片模型数据,求出部分区域碎片数目密度随高度变化关系,构造导弹空间飞行管道,将数目密度函数在导弹飞行管道内积分,从而得到管道内碎片数目的期望值,量化评估了导弹与空间碎片的碰撞风险。仿真结果表明,远程导弹与空间碎片的撞击风险数量级为10-7,而飞行管道内碎片数目数量级为10-2,表明空间碎片已威胁到远程导弹的安全飞行。     

【邀请论文】特朗普政府太空防卫战略调整的动因、特点与影响

面对太空领域变化的安全环境和自身实力的相对衰弱,特朗普政府对美国的太空防卫战略进行了重大调整。相比奥巴马政府的太空防卫战略,特朗普政府明确将太空作为新型作战域,加快天军建设,并以中俄为主要对手,联合盟友构建军民一体、内外联动的太空防卫体系。本文认为,特朗普政府对于太空防卫战略的调整凸显了美国欲加快太空武器化、谋求外空绝对军事力量优势的霸权企图。但这无疑会加剧目前愈演愈烈的太空“安全困境”,将更多国家拉入“太空军备竞赛”的恶性循环中,对国际太空安全和全球战略稳定带来消极影响。展望拜登政府的太空防卫政策,其军事色彩会略微下降,但也将更重视技术积累和太空的开发利用。