Defence spending and economic growth in South Africa: A supply and demand model*

This paper provides a contribution to the growing corpus of knowledge and understanding of the interaction between economic growth and defence spending in South Africa by specifying a Keynesian simultaneous equation model and estimating the system for the period 1961 to 1997. The model contains a growth equation, a savings equation, a trade balance equation and a military burden equation and when estimated by single equation and systems estimation methods is relatively well specified. There is evidence of an overall negative effect of military spending on the economy over this period, though the significance of individual coefficients is low. There is certainly no evidence of any positive impact, suggesting that cuts in military spending do present an opportunity for improved macroeconomic performance.     

Prices and quantities in the arms trade*

There are two main sources of information about the Arms Trade, SIPRI and ACDA. These two sources give very different pictures of the evolution of the market, primarily because their measures are designed to capture conceptually different features. Although they are both expressed in constant dollars, the SIPRI series is designed to be a volume index of physical transfers, the ACDA series a constant price value index. Thus in principle, the ratio of the ACDA to SIPRI series should provide an implicit price index of arms; though in practice there are many measurement problems. In this paper, we discuss the basis of these indices and show that the ratio, the implicit price, not only looks plausible in the light of the evolution of the market, but has a significant negative effect on the demand for arms imports in an econometric equation.     

How Different Terrorist Attacks Affect Stock Markets

Terrorist attacks adversely affect the Pakistani stock market. However, such effect is short-lived: the market recovers from terrorist shocks in one day. The impact of attack depends on the locations and types of attack. The more severe the attack (i.e. more people killed), the more negative is the KSE-100 index return. Most interestingly, stock market contains information about future attacks. In sum, different tactics of terrorists have varied effects on financial markets, which in turn can predict terrorist attacks.     

轮状病毒荧光定量PCR标准品的构建

采用MA104细胞系培养和T载体克隆技术,在轮状病毒结构蛋白VP4基因序列中设计合成引物,经过PCR扩增后将特异性产物与pMD-19-T载体连接,对获得的轮状病毒重组质粒标准品进行酶切鉴定和测序分析。利用常规PCR和荧光定量PCR方法对获得的重组质粒标准品进行特异性和灵敏度指标的检验。结果表明,将构建的重组质粒作为标准品制备标准曲线具有较高的扩增效率和良好的线性关系(斜率为-4.015,R2=0.991);荧光定量PCR熔解曲线分析表明,85.8℃的PCR产物是轮状病毒VP4基因序列的特异性产物,该标准品具有轮状病毒特异性;同时,所制备的重组质粒标准品在荧光定量PCR检测中具有较大的线性范围(5×101~5×1010拷贝/μL),每个梯度PCR反应最低可以检测到50拷贝的重组质粒,因而采用该标准品进行荧光定量PCR分析具有较高的检测灵敏度;此外,该重组质粒标准品具有较高的稳定性和重复性,3次独立实验的变异因数Cv<1.5%。构建的重组质粒标准品可以用做环境水体中轮状病毒的荧光定量PCR标准品。     

瞄准线稳定精度的影响因素仿真

瞄准线稳定精度是直升机载稳瞄系统的关键技术指标之一,它影响着系统的其他关键性指标如照射精度、跟踪精度、作用距离等。因此提高瞄准线稳定精度是设计和研制机载稳瞄系统至关重要的一项任务。论文分析和研究了影响瞄准线稳定精度的因素,并采用Simulink建立数学模型,对瞄准线稳定精度的影响因素进行仿真分析,得到各因素对稳定精度的影响趋势,为机载稳瞄系统的设计工作提供了理论基础。     

一种面向虚拟维修训练的拆装序列描述方法

通过分析机电产品的维修特点、虚拟维修训练的需求以及产品维护规程的结构特点,提出了一种采用树型和有向图混合结构来统一描述产品维护规程和拆卸安装序列的方法,并以Visual C++/MFC为工具,开发了维护规程控件,解决了虚拟维修训练中产品维护规程和拆卸安装序列的同步直观显示、约束关系解算、规程文件存取等问题,并为维护规程的可视化编辑提供了工具。实践表明,该方法满足虚拟维修训练对维护规程和拆装序列的描述要求。     

多无人机梯次攻击航路规划

为了解决多无人机协同攻击航路规划问题,基于一种雷达威胁等效方法,以及无人机在不同姿态下雷达散射截面RCS(Radar Cross-Section)值随之改变的特性,结合多机作战战术思想,提出了一种多无人机梯次协同攻击同一目标的方法,并利用Dijkstra算法进行多无人机航路规划.仿真结果表明,该方法具有更高的应用价值.     

利用拖尾能量提高蝶形天线辐射效率

蝶形天线在探地雷达中已有广泛的运用,但其辐射效率不高的问题一直存在。究其原因,主要是将近70%的辐射能量是以有碍目标探测的拖尾的形式存在。为了保证探测性能,传统上可观的拖尾能量往往以阻抗加载的方式被吸收掉。本文研究发现,当选择双极性单周波作为激励脉冲时,通过优化天线长度可以实现拖尾能量的有效利用,从而显著地提高蝶形天线的辐射效率。仿真实验结果表明,在较远的探测距离上本文方法可以将辐射效率提高近100%。通过实测实验进一步验证了本文方法的有效性。此外,本文所提的方法易于工程实现,工程应用价值十分明显。     

电离层不规则体对P波段星载SAR成像的影响

电离层不规则体导致星载合成孔径雷达（SAR）信号产生幅度及相位闪烁,严重影响低波段星载SAR的图像分辨性能。推导了具有普遍性的幂律谱对应的双频双点互相关函数。基于此研究了电离层对星载P波段SAR分辨性能的影响及其规律。研究表明,电离层不规则体导致星载P波段SAR两维分辨率恶化,图像峰值增益损失严重。电离层不规则体强度,谱指数,外尺度等参数的增大都会导致星载SAR图像分辨率及峰值增益进一步下降。基于相位屏技术的数值仿真结果验证了本文研究。     

LDO稳压器敏感度建模与仿真技术

基于LDO稳压器在电磁干扰（EMI）下产生直流偏移失效的机理分析,展开敏感度建模与仿真方法研究。使用一款实验芯片,创新地引入片上电压传感器,用于测试EMI在LDO稳压器内部的传播特性。在敏感度建模中,建立等效电路模型,通过直流功能测试,Z参数阻抗特性测试验证模型的正确性,将该模型用于LDO稳压器的敏感度预测。在敏感度仿真过程中,通过分析关键子电路和不断增加寄生元件,仿真不同寄生因素对敏感度影响的权重。将仿真结果与传导直接注入法（DPI）片上测试结果对比,仿真结果与DPI测试在频域1MHz至1GHz匹配。