NCO相位截断对频域抗干扰性能影响分析

频域抗干扰易于工程实现、窄带干扰抑制性能好,是目前全球卫星导航系统(Global Navigation Satellite System,GNSS)抗干扰接收机中广泛采用的抗干扰算法。频域抗干扰接收机普遍采用数控振荡器(numerically controlled oscillator, NCO)生成本振信号。由于硬件约束,通常需要对NCO进行相位截断。而NCO相位截断是否合理对抗干扰性能影响较大。针对该问题,从NCO相位截断导致的本振杂散着手,从理论上分析其对混频和频域抗干扰环节的影响。在此基础上,给出一种NCO查找表地址位宽的理论计算模型,使得接收机的载噪比损耗接近无NCO相位截断的频域抗干扰接收机。仿真表明,抑制带宽大于100kHz、干信比小于80dBc的窄带干扰时,计算的NCO查找表地址位宽不超过10bit。无NCO相位截断的频域抗干扰接收机相比,采用NCO混频的抗干扰接收机的载噪比损耗最多增加0.6dB。     

Book review

La Conversion économique du secteur militaire, J. FONTANEL, Economica, Paris, 1994, pp. 112. Paperback. ISBN 2–7178–2650–5.     

MILITARY EXPENDITURE AND ECONOMIC GROWTH IN MIDDLE EASTERN COUNTRIES: A DYNAMIC PANEL DATA ANALYSIS

Defence expenditures have both costs and benefits to the economy. The costs of defence expenditures are mainly emphasized as opportunity costs. On the other hand, defence spending may have growth‐promoting potential benefits: a rise in defence spending may result in a higher aggregate demand, production and employment. This paper examines empirically the effects of military expenditures on economic growth for Middle Eastern countries and Turkey, for the time‐period 1989–1999. The relationship between military expenditure and economic growth is investigated by using cross‐section and dynamic panel estimation techniques. Empirical analysis indicates that military expenditure enhances economic growth in the Middle Eastern countries and Turkey as a whole.     

基于ExtendSim的高炮群作战效能仿真分析

构建了高炮部队抗空袭作战仿真流程,并在特定作战条件下基于ExtendSim建立了高炮群雷达诸元法抗击敌空袭目标的作战仿真模型,对火控雷达组网工作模式下的扇形和线性配置的高炮群作战效能进行了仿真分析,结果表明在火控雷达组网模式下,高炮群整体探测范围增大,作战反应时间延长,提高了部队作战效能。     

高速互连网络中基于网卡的归约计算硬件卸载机制

聚合通信广泛应用于高性能计算的研究和工程领域。在大规模的科学和工程计算中,聚合通信开销占据很大比例,有时甚至可达到全部消息传递开销的80%,是高性能计算系统的性能瓶颈。因此提出了一种基于网卡的归约计算硬件卸载机制,通过在网卡上嵌入归约操作逻辑部件,实现了数据在传输过程中的计算,减轻了CPU的负担,降低了通信延迟。通过FPGA平台实现了16节点的归约操作实验,并基于xNetSimPlus模拟器模拟了不同节点规模的归约操作。实验证明,卸载机制能有效减少聚合通信中归约操作的时间,所提支持归约计算的网卡卸载机制最高可以加速归约操作2.71倍。     

Three-dimensional coordinates test method with uncertain projectile proximity explosion position based on dynamic seven photoelectric detection screen

To objectively obtain the three-dimensional coordinates of the projectile fuze proximity explosion when projectile intersects the head of missile target, we propose a dynamic seven photoelectric detection screen test method, which is made up of six plane detection screens and a flash photoelectric dynamic detection screen. The three-dimensional coordinates calculation model of the projectile proximity explosion position based on seven plane detection screens with dynamic characteristics is established. According to the relation of the dynamic seven photoelectric detection screen planes and the time values, the analytical function of the projectile proximity explosion position parameters under non-linear motion is derived. The projectile signal filtering method based on discrete wavelet transform is explored in this work. Additionally, the projectile signal recognition algorithm using an improved particle swarm is proposed. Based on the characteristics of the time duration and the signal peak error for the projectile passing through the detection screen, the signals attribution of the same projectile passing through six detection screens are analyzed for obtaining precise time values of the same projectile passing through the detection screens. On the basis of the projectile fuze proximity explosion test, the linear motion model and the proposed non-linear motion model are used to calculate and compare the same group of projectiles proximity explosion position parameters. The comparison of test results verifies that the proposed test method and calculation model in this work accurately obtain the actual projectile proximity explosion position parameters.     

Sequential learning versus no learning in Bayesian regression models

We consider two regression models: linear and logistic. The dependent variable is observed periodically and in each period a Bayesian formulation is used to generate updated forecasts of the dependent variable as new data is observed. One would expect that including new data in the Bayesian updates results in improved forecasts over not including the new data. Our findings indicate that this is not always true. We show there exists a subset of the independent variable space that we call the “region of no learning.” If the independent variable values for a given period in the future are in this region, then the forecast does not change with any new data. Moreover, if the independent variable values are in a neighborhood of the region of no learning, then there may be little benefit to wait for the new data and update the forecast. We propose a statistical approach to characterize this neighborhood which we call the “region of little learning.” Our results provide insights into the trade‐offs that exist in situations when the decision maker has an incentive to make an early decision based on an early forecast versus waiting to make a later decision based on an updated forecast. © 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 532–548, 2014     

The sixteenth-century antecedents of special operations ‘small war’

The first conceptual, theoretical treatises about small war (la petite guerre) as special operations appeared only from the middle of the seventeenth century. The term is not used in the eighteenth-century sense of ‘special operations’ in older sources. The supposed absence of any treatment of the subject is surprising considering the obsession with the ‘art of war’ in the Renaissance, but other authors attribute it to a supposed antinomy between chivalric ideals and irregular warfare. But the absence of explicit manuals on the subject is not evidence of absence of advanced reflection on this kind of operations in the Middle Ages and in Early Modern times. We should thus look elsewhere, in other genres, for writings that contain and pass on military knowledge. Epics, romances, educational and military treatises, and memoirs in fact contain elements of a theory of special operations, even though these genres differ from our conception of rationality inherited from the Enlightenment.     

Guerrillas and bandits in the Serranía de Ronda, 1810–1812

The Spanish Guerrilla (1808–1812) which has given its name to ideologically motivated insurgencies is usually portrayed as a patriotic uprising against the French occupation forces of Napoleon. It was that, in part, but also many other things besides. This case study illustrates its overlap and convergence with banditry but also with social unrest turned into uprisings directed by poor Spaniards against their creditors, as in the storming of Ronda by insurgents in 1810. From the propaganda of the day to the subsequent Spanish patriotic historiography, there has been a tendency to exaggerate the amplitude of events and also the damage that was done to the French forces and the casualty figures inflicted on them.     

信息系统体系作战弹药保障能力评估

弹药信息化是武器装备信息化的重要组成部分,直接影响战斗力的生成。如何分析、评估保障单位在信息系统体系作战弹药信息化保障能力的建设水平,对我军信息化建设至关重要。在分析影响弹药信息化保障能力形成的主要因素的基础上,构建了符合我军弹药信息化保障能力特点的评估指标体系,提出了一种基于主成分和集对分析法综合分析的基于信息系统体系作战弹药信息化保障能力评估方法,通过该方法可求得指标权重,最终获得被评估单位弹药信息化保障能力的整体建设水平。结合实例分析,验证构建的评估模型能够用于我军基于信息系统体系作战弹药信息化保障能力的评估,进一步为如何提高弹药信息化保障能力提供技术指导。