基于装备水平和知识的空中作战效果分析

分析了按作战效果进行空军武器装备需求分析的三种常用方法的特点,建立了一种全自动化解算模型,比较完整地讨论并描述了根据装备水平分析作战效果时需要考虑的关键因素,总结了需要使用的相关军事知识,并给出了表达方法,研究了推理机制.构建了各种战斗类型的效果评估模块,实现了软件系统并应用于一个重要课题研究,取得了比较理想的效果.     

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。     

农村文化建设对农村社会稳定的双向效应

社会稳定是改革发展的重要前提,而保持农村稳定是全社会稳定的关键。维护农村社会稳定根本途径在于文化建设,但文化建设对农村社会稳定有双向效应。文化建设对农村社会稳定的正面效应有减贫效应、社会结构优化效应、社会控制效应、社会心理优化效应和社会化效应,而文化建设的受益不均衡效应、虚化效应、过度社会动员效应及其信息失稳效应等又不利于农村社会稳定。因此,要充分重视农村文化建设的积极作用,也要清醒认识其负面效应,并为维护农村社会稳定考虑扬正抑负的对策。     

实验课课堂教学有效性的组织策略

本文从教学的有效性理论出发，通过分析，给出了在实验课课堂教学中实行滚动式、分层次教学的可行性分析，给出了具体的组织管理细节。讨论了以实验课为试点的优势及其可行性方案。     

一种消除直线永磁无刷直流电机边端效应对换相时机影响的方法

电磁弹射用直线永磁无刷直流电机的永磁体动子具有开断结构,使动子边端的磁场分布发生变形。当采用霍尔元件检测磁场实现换相时,这种边端效应就会影响换相时机。分析了这类电机的换相机理和动子开断结构对换相时机的影响,指出这类边端效应受极弧系数影响显著,并提出了利用不对称滞环比较器或简易单限比较器对霍尔输出信号进行处理从而消除这类边端效应影响的方法,实验验证了简易单限比较器方案的可行性。     

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.