BTT 导弹自动驾驶仪的多变量频域法解耦设计

研究了一种耦合严重的ＢＴＴ 导弹偏航－滚动通道非方阵模型的自动驾驶仪的设计问题。首先采用内闭环回路法对模型进行了方阵化, 然后采用基于奈奎斯特阵列法思想的多变量频域法进行了设计。仿真表明了自动驾驶仪设计的解耦效果明显     

采用固液冲压发动机的地空导弹弹道建模

针对采用固液混合冲压发动机的地空导弹弹道设计中出现的新问题, 给出了解决这些问题的弹道设计方法, 并利用弹道仿真对其进行了验证。     

特大规模组合电路高速测试生成系统ATGTA-1

针对特大规模组合电路和全扫描设计电路提出了一种高速测试生成方法，并建成了相应的测试生成系统ＡＴＧＴＡ－１。该系统采用有限回溯测试模式产生方法生成测试码，采用ｎ（机器字长）个测试码并行的单故障传播方法模拟验证测试覆盖。测试生成与故障模拟为ｎ对１紧耦合集成方式。该系统运行１０个Ｂｅｎｃｈｍａｒｋ电路，取得了低测试长度、高故障覆盖、高效率的良好效果。     

基于故障树分析的航空装备体系结构贡献率评估方法

针对航空装备体系构成复杂的特点,将故障树分析引入航空装备体系结构贡献率评估问题,提出基于故障树分析的评估方法.从作战装备、信息支援装备和保障装备三个方面构建航空装备体系结构,建造航空装备体系结构故障树;采用底事件的关键重要度指标来计算航空装备的体系结构贡献率,建立基于关键重要度的航空装备体系结构贡献率评估模型;以某航空...     

酚醛-石英混杂纤维增强苯并噁嗪复合材料高温失效特征

通过模压工艺制备了酚醛-石英混织纤维增强苯并噁嗪复合材料(P-Q/BZ)试样,考察了其力学性能、烧蚀性能和耐冲刷性能,分析了该试样在高温环境中的主要失效特征,研究其在高温环境中的适用性。结果表明,未经热处理的P-Q/BZ试样平均弯曲强度、弯曲模量和层间剪切强度分别为283 MPa、10.8 GPa和22.6 MPa;经300℃,N_2处理15 min后,试样均匀膨胀,厚度增加22%,弯曲强度、弯曲模量和层间剪切强度分别下降58%、41%和58%;在氧乙炔焰的平均质量烧蚀率和线烧蚀率分别为0.048 4 g/s和-0.081 mm/s,烧蚀后试样宏观不分层,表面炭层微观分层严重,酚醛纤维热解炭、树脂基体热解炭、熔融石英纤维以及碳硅氧化产物相互分离;该试样耐冲刷能力差,在发动机尾焰烧蚀平台模拟的热-力耦合环境中的质量损失率高达59%。P-Q/BZ复合材料需要解决热解膨胀问题,进一步提高抗冲刷性能。     

美国应对外空国际条约的做法简析

针对现行国际空间法存在的诸多漏洞和缺陷,国际空间大国积极利用这些漏洞寻求开展外空试验的依据,并规避法律的约束以发展外空武器装备,使得外空存在被武器化的风险,外空军备竞赛日益激烈。因此,研究并利用外空条约、关注空间大国开展外空试验的现实做法,可以为开展外空活动提供借鉴和依据。本文重点研究了美国海基反卫试验和轨道快车试验,从试验背景、目的、对外口径以及对外反应几个方面,综合对比分析了试验的现实做法,剖析了美国应对外空条约的做法,从技术上、政策上和法律上得出了如何应对的方法和途径。研究成果可为我国合理合法地开展外空行动提供借鉴,从而赢得国际社会的认可。     

近地卫星Ka频段数传链路抗雨衰自适应模式设计

针对近地卫星数传时的信道时变性和严重的Ka频段雨衰现象,采用自适应编码调制(Adaptive Coding and Modulation, ACM)技术能够充分利用链路资源,相对于传统的固定编码调制方式,进一步提高链路的数据吞吐量。提出近地卫星Ka频段数传链路ACM模式设计方法,在降雨环境下建立Ka频段数传链路模型,根据链路预算的信道状况确定ACM选用模式;采用基于导频符号的最大似然信噪比估计算法结合移动平均的平滑方法实现信道估计,有效地减小了估计值的波动。仿真结果表明,无论晴天还是雨天,采用提出的卫星数传链路ACM模式设计方法,能够在保证系统可靠性的同时获取较高的数据吞吐量。     

Tripwires and free-riders: Do forward-deployed U.S. troops reduce the willingness of host-country citizens to fight for their country?

This article investigates the relationship between U.S. overseas troops and the willingness of the citizens of host states to fight for their country. The study joins the long-running debate about burden-sharing and free-riding among U.S. allies. Unlike most previous empirical studies, we focus on non-material or intangible measures of the underlying concepts. Our dependent variable estimates the proportion of citizens expressing a willingness to fight for their country. Scores at the aggregate-national as well as the individual level are shaped by the presence of U.S. military forces, which act as a “tripwire” signaling credible security commitments. This increases opportunities of (non-material) free-riding. We present both bivariate and multivariate analyses covering the period 1981–2014 to test this supposition. Findings indicate that once U.S. troop levels reach a certain threshold (between 100 and 500 troops), citizens’ willingness to fight drops significantly. This likely reflects non-material free-riding.     

Humanitarians at sea: Selective emulation across migrant rescue NGOs in the Mediterranean sea

Between 2014 and 2017, no less than 10 different non-governmental organizations (NGOs) conducted maritime Search and Rescue (SAR) operations off the coast of Libya. By rescuing over 100,000 migrants in three years, these NGOs became the largest provider of SAR in the Mediterranean. The theory of institutionalism suggests that organizations conducting similar activities are likely to converge in a process of mimetic isomorphism, deliberately imitating one another to increase their effectiveness and cope with uncertainty. These 10 SAR NGOs, however, developed two different rescue models: While some rescued migrants and disembarked them in Italian ports, others only simply assisted those in distress until the arrival of another ship transporting them to land. They also cooperated with Italian and European authorities to different degrees. Why did SAR NGOs imitated many elements of existing non-governmental rescue models, but discarded some others? This article argues that differences in material capabilities and organizational role conceptions are crucial to explain why newer SAR NGOs have imitated most but not all of their predecessors’ policies, engaging in a process of “selective emulation.”     

Dynamic coordination of production planning and sales admission control in the presence of a spot market

We consider the decision‐making problem of dynamically scheduling the production of a single make‐to stock (MTS) product in connection with the product's concurrent sales in a spot market and a long‐term supply channel. The spot market is run by a business to business (B2B) online exchange, whereas the long‐term channel is established by a structured contract. The product's price in the spot market is exogenous, evolves as a continuous time Markov chain, and affects demand, which arrives sequentially as a Markov‐modulated Poisson process (MMPP). The manufacturer is obliged to fulfill demand in the long‐term channel, but is able to rein in sales in the spot market. This is a significant strategic decision for a manufacturer in entering a favorable contract. The profitability of the contract must be evaluated by optimal performance. The current problem, therefore, arises as a prerequisite to exploring contracting strategies. We reveal that the optimal strategy of coordinating production and sales is structured by the spot price dependent on the base stock and sell‐down thresholds. Moreover, we can exploit the structural properties of the optimal strategy to conceive an efficient algorithm. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010