高能离子在材料中输运的蒙特卡罗模拟

利用蒙特卡罗方法对高能离子在材料中的输运进行了计算机模拟研究 ,入射高能离子与靶材料的作用近似为核散射和电子作用两个独立的部分 ,核散射能量损失采用经典两体碰撞近似 ,通过对碰撞参数的随机抽样得到散射角 ,电子能量损失高能时采用Bethe-Bloch公式 ,低能时采用Lindhard -Scharff公式 ,中能时采用插值公式。最后对高能铁离子入射于铝、硅材料的输运进行了模拟计算 ,给出了模拟结果并进行了分析。     

强流相对论电子束(REB) 电子能量径向分布的测量方法

本文介绍一种REB电子能量径向分布的测量方法。利用REB电子轰击阳极靶产生的“厚靶”韧致辐射的零角度测量,确定束电子能量的径向分布,从而判断REB的居中性和能量的均匀性。     

一种辐射屏蔽模拟计算的方法

本文论述了用蒙特卡罗方法直接模拟计算非带电粒子辐射的屏蔽穿透概率问题,讨论了粒子穿透概率无偏估计的两种实际情况,探讨了将粒子输运理论应用于解决实际辐射物理问题的途径。     

基于蒙特卡罗方法的多散射修正模型

针对现有的基于蒙特卡罗方法的非视线传输模型的不足和局限性,提出了基于蒙特卡罗方法的多散射修正模型,给出了模型的数学描述。利用坐标系变换方法,得出了光子迁移的坐标递推公式。设计了接收判断机制,给出了到达时间的计算公式。通过跟踪大量光子的随机迁移,验证了光子传输的多散射现象。绘制了接收天线功率密度曲线,模拟了脉冲展宽效应。比较结果表明,在满足单散射近似的条件下,该模型与Luett-gen单散射模型吻合较好;在不满足单散射近似条件时,该模型得出的接收功率密度大于Luettgen单散射模型的接收功率密度,分析了结果的正确性,并指出了现有模型信道零延迟的错误。理论分析表明,模型能准确反映信道的时延特性。     

吸气式激光推进中空气对CO_2激光的吸收系数计算

比较分析了吸气式激光推进中空气对CO2激光的3种吸收机制,列出了相应的吸收系数计算公式。通过计算发现,自由-自由吸收对应的逆韧致吸收系数占总吸收系数的比例几乎达到80%,即在较强的激光辐照作用下,由于电子温度很高,高温空气主要通过逆韧致方式吸收入射激光能量。计算结果可以用于吸气式激光推进的能量沉积过程研究。     

用蒙特卡罗方法计算快中子屏蔽体的厚度

文中使用蒙特卡罗方法,模拟了３００ｋｅＶ氘束流Ｔ（ｄ,ｎ）４Ｈｅ中子源发出的中子在球壳屏蔽体介质铁中的输运规律;对计算结果进行解释和分析,得出将中子能量从１４ＭｅＶ慢化到１ＭｅＶ以下所需的最佳屏蔽厚度。所得结果与国际上同类屏蔽体所取参数相一致,具有一定的应用参考价值。     

用蒙特卡罗方法计算双层介质空心圆柱体内的中子辐射场

本文用蒙特卡罗方法计算了有限长、双层介质空心圆柱体在平行入射的中子束的辐射下,其中的中子通量空间分布、中子能谱和中子时间谱。入射中子束沿 y 轴方向平行射到圆柱体外壁上。入射中子能量为19.2MeV～0.001MeV。模拟过程采用分区分群、简单加权和统计估计等技巧。双层介质中的中子飞行距离抽样用逐区推进法。     

光电电子进攻运用方式与需求

光电对抗的基本内容包括光电对抗侦察、光电干扰和光电电子防御三个基本内容[1]。但随着高能激光武器的逐步走向成熟,反激光的反辐射武器的试验论证,光电干扰已经不能涵盖全部进攻性光电对抗行动。参照美军的电子攻击(EA)定义[2],可将进攻性光电对抗表述为光电电子进攻,指利用辐射、散射、吸收光波能量,改变目标的光学特性和使用定向能以及相关的硬摧毁手段,以削弱或破坏敌方光电设备使用效能的攻击行动,主要包括光电干扰、高能激光攻击、反激光辐射攻击和电磁脉冲毁伤等(见图1)。下面按照目前的技术水平和作战(包括演习)实践,兼顾技术的可…     

卫星柔性热控薄膜材料充放电效应试验

针对柔性热控薄膜材料导电/绝缘多层复合、微纳尺寸厚度的结构特点,采用10～70 KeV电子辐照的方法开展了kapton基二次表面镜薄膜材料充放电特性的测试试验,获得了表面充电电位、静电放电频次等关键参数,并采用蒙特卡罗方法研究了辐照电子在多层薄膜材料内的输运规律。研究结果表明由于kapton基二次表面镜薄膜结构的特殊性,当辐照电子能量为10 KeV时未发生静电放电现象,随着电子能量不断增加,薄膜材料的表面充电电位幅值与静电放电频次呈先上升后下降的变化规律,且在电子能量为25 KeV时空间充放电效应最为显著。     

诱饵球镜面反射内壁的辐射传递系数计算北大核心

针对内表面具备镜面反射特性的空间诱饵球,基于蒙特卡罗方法建立漫发射模型,推导光线的最大反射次数,利用光线在球腔的传播特性求解光线与球壁的多次反射交点,计算球面微元吸收的光束能量,获取不同反射率情况下单一球面微元对全部球面微元的辐射传递系数。计算结果表明,单一微元对球面各微元的辐射传递系数中存在2个峰值,分别为微元对其自身的辐射传递系数,以及微元对其球对称微元的辐射传递系数。随着反射率的增大,微元对其自身的辐射传递系数逐渐接近于微元对其球对称微元的辐射传递系数;当反射率接近于1时,两者的值近似相等。     

Reviews

Douglas S. Derrer, We Are All the Target: A Handbook of Terrorism Avoidance and Hostage Survival. Annapolis, MD: US Naval Institute Press, 1992. Pp. x+135, notes, index. $14.95. ISBN 01–55750–150–5

Ian Knight, Zulu: Isandlwana and Rorke's Drift, 22–23 January 1879. London: Windrow & Greene, 1992. Pp.136, 150 illus., incl 8 colour plates, maps, biblio. £35. ISBN 1–872004–23–7

Ian Knight, By the Orders of the Great White Queen: Campaigning in Zululand through the Eyes of the British Soldiers, 1879. London: Greenhill Books and Novato: Presidio Press, 1992. Pp. 272, 17 illus., 1 map. £18.95. ISBN 1–85367–122–3

Manfried Rauchensteiner and Erwin A. Schmidl (eds.), Formen des Krieges: vom Mittelalter zum ‘Low‐intensity’ Conflict’. Graz : Verlag Styria, 1991. Pp.208. DM35. ISBN 3–22–12139–7

Harold J. Kearsley, Maritime Power and the Twenty‐First Century. Dartmouth: Dartmouth Publishing Company, Limited, 1992. Pp.xv + 203, 13 diagrams, index. £32.50. ISBN 1–85521–288–9     

An Unlikely Alliance: Portuguese and South African Airpower in Angola, 1968–1974

The war that Portugal was obliged to fight in Africa began in 1961 and immediately stretched the resources of its armed forces. Nowhere was this thinness more apparent than in policing the vast territory of Angola. The east and southeast of Angola were particularly vulnerable, as the area was a vast, sparsely populated region characterised by enormous featureless plains or chanas covered in tall grass and broken by an extensive river system and mountainous forests. The only military solution to policing these immense spaces was aviation and specifically the helicopter that could carry troops into battle, protect them with a gunship and bring them home when the operation was concluded. The immediate problem for the Portuguese Air Force (Força Aérea Portuguesa or FAP) in Angola and elsewhere was a scarcity of helicopters. The solution was an alliance with South Africa, which had a strong inventory of Alouette IIIs, to help in policing the east. This move was likewise in the interest of South Africa, as its threat came from Zambia through south-eastern Angola. This article examines the strategic and tactical development of this unusual, cross-cultural alliance and the symbiotic relationship that resulted in destruction of the enemies of both in Angola.     

Panjwai: a tale of two COINs in Afghanistan

The US Army has two approaches to counterinsurgency operations in Afghanistan. One is hard, or combat-focused, and the other is soft, or development-focused. This study examines two US Army task forces deployed to Panjwai District, Afghanistan from 2012 to 2013. CTF 4-9 and 1-38 offer a meaningful comparison because they pursued these contrasting approaches among the same population and against the same enemy at the same time and place. The study compares each unit’s approach and finds that neither approach was successful absent the other. The article concludes by recommending further research into combining the approaches at the operational level.     

国内外结构钢焊条研究的现状与发展

本文主要介绍了国外焊条的现状和发展趋势,包括焊条的高韧性、高效率、低尘低毒和耐吸潮性能,为国内的焊条研究提供了参考依据。     

A Sign of Victory?: ‘Scottish Swords’ and Other Weapons in the Possession of the ‘Auld Innemie’

Many late medieval documents, notably inventories of arms and armour, of Englishmen contain references to ‘Scottish swords’ and other weapons. What did the compilers of these documents mean when they described a weapon as ‘Scottish’? How did such weapons come to be in the possession of these men? This article will attempt to explain this phenomenon drawing on primary documentary sources and surviving material culture from Glasgow Museums’ collections and others, as well as artworks from the period.     

线性核时频信号表示及其仿真

根据ｃｈｉｒｐ信号在模糊域的特点,本文提出了线性核时频表示方法。这种方法在提高分辨率、消除交叉项以及抑制噪声等方面都具有较高的性能。理论分析和实验结果都证实了这种方法的有效性     

Putin – the masked nemesis of the strategy of ambiguity

Recent events demonstrate the complex and adaptive approach employed by Russia to reassert influence in Europe. The changing face of Russia’s strategy commenced in 2007 when it launched a crippling cyber-attack against Estonia. This was followed by a large Russian conventional attack against Georgia in 2008, occupying two large areas of the nation. 2014 witnessed the Russian annexation of Crimea where in just a week, Russia seized control of Crimea “without firing a shot.” The annexation of Crimea was rapidly followed by a Russian inspired and led subversive war in eastern Ukraine. The common thread among these diverse Russian operations is its use of ambiguity to confound and confuse decision makers in the West.     

Cyberpower in Strategic Affairs: Neither Unthinkable nor Blessed

Abstract

This article explores the effect of connectivity on strategic affairs. It argues that the effect on war's character is potentially, although not yet shown in practice, considerably large. Its effect upon the distribution of power among states in the international system is small, contrary to the claims of ‘cyberwar’ alarmists. All told, however, its effect upon strategic affairs is complex. On the one hand, it represents a significant advance in the ‘complexification’ of state strategies, understood in the sense of the production of intended effects. On the other hand, strategists today – still predominantly concerned with the conflicts and confrontations of states and organised military power – are generally missing the power which non-traditional strategic actors, better adapted to the network flows of the information age, are beginning to deploy. These new forms of organization and coercion will challenge the status quo.