计算机网络攻击效果评估技术研究

计算机网络攻击效果评估技术是信息系统安全评估中一个重要而具有挑战性的课题。目前 ,相关的理论尚不成熟 ,有关的研究报道较少。简要总结了当前已经存在的主要信息安全的评估方法 ,在此基础上 ,从便于实际度量和计算的角度出发 ,提出了基于网络信息熵的评估技术、基于系统安全层次分析的安全评估框架和基于指标分析的网络攻击效果综合评估技术等三种评估模型 ,并分析了各自在使用中应注意的问题     

舰载激光武器系统建模与仿真技术

针对舰载激光武器系统仿真技术发展要求和应用方向,通过对舰载激光武器系统组成、功能和作战过程的分析,归纳整理出一套较完整的舰载激光武器仿真模型,其中对激光能量传输仿真模型和毁伤效果仿真模型进行详细描述;并提出仿真软件设计方案,包括软件功能组成、软件结构、软件运行流程等仿真软件设计要点;最后介绍了软件的仿真输出结果。文中设计的仿真软件可支持舰载激光武器系统的设计开发,也可以应用到舰船新型防空反导火控系统仿真认证中。     

拉压异性材料厚壁圆筒和厚壁球壳的极限载荷分析

本文利用库仑屈服准则,研究了拉压异性材料厚壁圆筒和厚壁球壳的弹性极限载荷和塑性极限载荷,得出了新的结果和结论。计算结果表明,考虑了材料的拉压异性之后,厚壁圆筒和厚壁球壳的极限载荷均有明显提高。     

弹药保障效果评价的AHP-FUZZY方法

简要分析了我军弹药保障效果评价工作的不足之处,在此基础上,综合运用层次分析技术（AHP）和模糊评判技术（Fuzzy）,对战场上弹药保障效果评价进行了探讨。运用AHP法建立了弹药保障效果评价的层次结构模型,并详细论述了运用Fuzzy方法评价弹药保障效果的实现过程和注意问题。     

火炮射击精度的灰色系统预测

本文应用灰色系统预测的理论与方法,建立了射击精度的子系统与系统的预测模型,为从微观、宏观上控制误差,提高射击效果,提出了一种科学的预测方法。     

The Economic Consequences of the Libyan Spring: A Synthetic Control Analysis

Abstract

In 2011 a wave of revolutionary movements, the so-called Arab Spring, spread in the Middle East and North Africa. Libya was one of the most affected countries, ending Gaddafi’s dictatorship after an international intervention and a civil war. This paper assesses the effects that this revolution had on Libyan economy. The analysis is made by means of the synthetic control method. Our estimates for the 2011–2014 period show (i) a cumulative loss in the growth rate of per capita real GDP of 64.15%; (ii) a cumulative loss in per capita real GDP of 56,548 dollars; and (iii) a cumulative loss in the aggregate real GDP of 350.5 billion dollars.     

Effects of Mg/PTFE pyrotechnic compositions on reignition characteristics of base bleed propellants and heating mechanism

The effects of magnesium/polytetrafluoroethylene (Mg/PTFE) pyrotechnic compositions on the coupled flow field and reignition mechanism are important aspects governing the performance and range of base bleed projectiles (BBPs).Owing to a decrease in pressure and temperature when the BBP leaves the muzzle,rapid depressurization occurs,which extinguishes the base bleed propellant.The Mg/PTFE py-rotechnic composition pressed in the igniter of the base bleed unit (BBU) provides additional energy to the BBU via a chemical reaction.Thus,the extinguished base bleed propellant is reignited under the effect of high-temperature combustion gas jets from the igniter.In this study,a numerical analysis is conducted to evaluate the effects of PTFE and Mg granularity as well as Mg/PTFE pyrotechnic compo-sitions.Owing to the rapid depressurization,the temperature and pressure was found to decrease for different Mg/PTFE pyrotechnic compositions.However,the depressurization time increased as the PTFE granularity increased,the Mg granularity decreased,and the Mg content increased.When the pressure in the combustion chamber of the BBU decreased to the atmospheric pressure,the combustion gas jets from the igniter expand upstream (rather than downstream).However,these combustion gas jets exhibit different axial and radial expansion characteristics depending on the pyrotechnic compositions used.The results show that the reignition delay time,td,of the base bleed propellant was 377.608,94.27,387.243,523.966,and 221.094 ms for cases A-E,respectively.Therefore,it was concluded that the Mg/PTFE pyrotechnic composition of case B was the most beneficial for the reignition of the base bleed propellant,with the earliest addition of energy and mass to the BBP.     

Numerical investigation of the failure mechanism of cubic concrete specimens in SHPB tests

Cylindrical specimens are commonly used in Split Hopkinson pressure bar (SHPB) tests to study the uniaxial dynamic properties of concrete-like materials.In recent years,true tri-axial SHPB equipment has also been developed or is under development to investigate the material dynamic properties under tri-axial impact loads.For such tests,cubic specimens are needed.It is well understood that static material strength obtained from cylinder and cube specimens are different.Conversion factors are obtained and adopted in some guidelines to convert the material strength obtained from the two types of specimens.Previous uniaxial impact tests have also demonstrated that the failure mode and the strain rate effect of cubic specimens are very different from that of cylindrical ones.However,the mechanical background of these findings is unclear.As an extension of the previous laboratory study,this study performs numerical SHPB tests of cubic and cylindrical concrete specimens subjected to uniaxial impact load with the validated numerical model.The stress states of cubic specimens in relation to its failure mode under different strain rates is analyzed and compared with cylindrical specimens.The detailed analyses of the numerical simulation results show that the lateral inertial confinement of the cylindrical specimen is higher than that of the cubic specimen under the same strain rates.For cubic specimen,the corners are more severely damaged because of the lower lateral confinement and the occurrence of the tensile radial stress which is not observed in cylindrical specimens.These results explain why the dynamic material strengths obtained from the two types of specimens are different and are strain rate dependent.Based on the simulation results,an empirical formula of conversion factor as a function of strain rate is proposed,which supplements the traditional conversion factor for quasi-static material strength.It can be used for transforming the dynamic compressive strength from cylinders to cubes obtained from impact tests at different strain rates.     

论环境侵权民事责任的构成要件

随着社会经济的发展,环境污染已成为一个不能回避的社会话题。国家要想在将来寻求长远的发展,必须在现有立法的基础上,进一步完善环境保护的法律机制,从而实现社会的和谐。从环境侵权民事责任构成要件角度出发,阐述了如何保护受害人的合法权益,如何在经济发展的同时从根本上正确处理人与自然环境之间的关系。     

系统目标毁伤效果指标建模方法探讨

探讨常规导弹打击目标类群中系统目标的毁伤效果指标的建模方法。在对毁伤效果指标、毁伤意图、目标易损性等概念进行深入分析基础上,提出基于目标功能易损性的系统目标毁伤效果指标建模的思想。根据系统目标功能受损情况,归纳出三类毁伤效果指标常用的建模方法:效能模型、失效模型及基于毁伤的保障度模型。举例说明了方法的有效性,可为导弹武器攻击效能评估、耗弹量计算和瞄准点选择等提供定量决策依据。