基于中位秩的动态可靠性增长模型

给出了一种动态可靠性增长模型。首先利用统计中的中位秩法结合试验数据确定各个增长阶段的失效率 ,这一技术可以很好地解决小子样问题 ,并且由于利用了动态建模的思想 ,因而可以客观地反映系统的实际状态。其次 ,该模型继承了传统Duane模型简单、直观、易于进行参数估计的优点 ,同时又很好地处理了传统Duane模型所不适用的分阶段、多场景试验的情形 ,因而有很广阔的工程应用前景。最后通过仿真实例验证了该模型的正确性     

Economic sanctions and official ethnic discrimination in target countries, 1950–2003

Conventional studies on the consequences of sanctions tend to focus on the target society as a whole without specifying how foreign economic pressures might affect the well-being of vulnerable groups within target countries – the same groups who often disproportionately bear the burden of sanctions. This study explores the extent to which sanctions increase the likelihood of discriminatory government practices against one of the globally most vulnerable groups, ethnic groups. It is argued that sanctions contribute to the rise of official ethnic-based economic and political discrimination through contracting the economy and creating incentives for the target government to employ ethnic-based discriminatory policies. Using data on over 900 ethnic groups from 1950 to 2003, the results lend support for the theoretical claim that sanctions prompt the government to pursue ethnic-based discriminatory economic and political practices in multiethnic countries. The findings also indicate that multilateral sanctions are likely to be more harmful to the well-being of ethnic groups than sanctions levied by individual countries. Further, the negative effect of comprehensive sanctions appears to be greater than that of sanctions with moderate and limited impact on the target economy. The regime type of the target state, on the other hand, appears to have a significant role only in conditioning the hypothesized effect of sanctions on economic discrimination. Overall, this study’s focus on a vulnerable segment of the target society – ethnic groups – offers a greater understanding of the consequences of sanctions. It also provides additional insight as to how, in multiethnic countries, political elites might domestically respond to external pressures to retain power.     

Growth recovery after civil conflict: a fractional integration approach

Using recent econometric techniques based on fractional integration, we find that developing countries recover their economic growth faster than developed countries in response to a shock. Following this methodology, we find that longer civil conflicts are associated with a faster recovery process. We further investigate this issue by exploring correlations with components of GDP, military spending, institutions and aid and find heterogeneous effects of these channels by duration of conflict. Higher government spending is correlated with faster recoveries post longer conflicts, and higher consumption spending is linked to faster recoveries following shorter conflicts. Military spending appears to be driving the government expenditure that makes countries recover from longer conflicts. More democratic institutions are associated with faster recoveries post short wars but slower recoveries following long wars.     

装备维修性增长及其基本过程研究

为了解决当前装备的维修性问题，揭示维修性发展的一般规律，进行了维修性增长的研究。首先阐明了装备维修性形成与演变的一般规律，继而提出了维修性增长的概念，重点研究了维修性增长的内涵与增长的一般过程，最后对解决增长问题所需的模型进行了分类，为增长技术的深入研究奠定了基础。     

层裂问题的数值研究

本文对Carrol、Holt 和Johnson提出的延性材料损伤断裂进行了改进。在模型中考虑了材料的硬化效应和空穴成核的影响。用数值方法模拟了高速碰撞中OFCH 铜和铝的层裂过程,其结果与实验吻合得相当好。     

Educate or Adjudicate? Socioeconomic Heterogeneity and Welfare

I present a formal framework to explore the welfare and distributional effects of a government’s optimal choice over two types of public spending in a closed economy: domestic security (DS) and investment in social capital (SC). Production is characterized as a function of social and physical capital stocks that both vary across the regions. DS stands for total factor productivity, while SC stands for human capital and civic cooperativeness combined. SC accumulates via public spending on universal primary education, cultural, and civic events and such, and is exposed to regional spillover effects. Numerical simulations of the static solution of the government’s welfare maximization problem reveal that the optimal rate of spending on SC (m^*) is negatively related with the income share of physical capital, SC spillovers and fiscal decentralization. Simulations also show that SC homogeneity is positively associated with both the level and equitability of aggregate income. The maximum attainable levels of income, welfare and social cohesion and the most equitable incomes are all observed to realize at some intermediate range of m^* values. In case DS augments SC, however, social cohesion improves and welfare declines monotonously in m^*.     

Military Expenditure,Economic Growth and Heterogeneity

This paper examines the impact of military expenditure on economic growth on a large balanced panel, using an exogenous growth model and dynamic panel data methods for 106 countries over the period 1988–2010. A major focus of the paper is to consider the possibility group heterogeneity and non-linearity. Having estimated the model for all of the countries in the panel and finding that military burden has a negative effect on growth in the short and long run, the panel is broken down into various groupings based upon a range of potentially relevant factors, and the robustness of the results is evaluated. The factors considered are different levels of income, conflict experience, natural resources abundance, openness and aid. The estimates for the different groups are remarkably consistent with those for the whole panel, providing strong support for the argument that military spending has adverse effects on growth. There are, however, some intriguing results that suggest that for certain types of countries military spending has no significant effect on growth.     

Resource rents,institutions, and violent civil conflicts

Natural resources have been blamed for inducing slow growth and sparking civil conflicts and violence. This paper first develops a model to account for the hazard of armed civil conflicts as a manifestation of the natural resource curse, which is mediated by the quality of both economic and political institutions. We then use recently published data on institutional quality and natural resource rents to measure the potential impact of the resource curse on violent civil conflicts using a panel of data for over 100 countries in the period 1970–2010. Our model explicitly accounts for the role of good economic and political institutions in deterring the recourse to violence as well as the extent to which they might weaken the resource rents effect.     

含噪稀疏信号重构的l0范数期望值最小化方法

压缩感知理论是对信号压缩的同时进行感知的新理论,而如何通过有限的测量值重构稀疏信号是压缩感知理论中的核心问题。针对测量值受噪声污染的含噪稀疏重构问题,提出了近似l0范数期望值最小化方法。该算法基本思想是将含噪稀疏重构问题转化为近似l0范数期望值最小化问题,并利用噪声的统计特征将随机最优化问题化简为常规的最优化问题,然后采用最速下降法求解。数值仿真表明,本文提出的方法具有更好的重构精度,且计算量较小。     

不同攻角下AUV回收过程中的水动力规律

通过对AUV(Autonomous Underwater Vehicle)回收过程中运动规律的研究和对纳维—斯托克斯方程(Navier-Stokes equations)及其求解方法的分析,基于CFD(Computational Fluid Dynamics)理论建立了AUV回收运动的三维计算模型,并使用CFD软件完成其物理模型的建立、网格的划分及求解设置。在此基础上对AUV回收过程中的阻力、升力干扰进行分析计算,得到不同攻角下AUV所受到的水动力干扰与AUV和回收平台之间距离的相互联系。