An integral equation for the second moment function of a geometric process and its numerical solution

In this article, an integral equation satisfied by the second moment function M₂(t) of a geometric process is obtained. The numerical method based on the trapezoidal integration rule proposed by Tang and Lam for the geometric function M(t) is adapted to solve this integral equation. To illustrate the numerical method, the first interarrival time is assumed to be one of four common lifetime distributions, namely, exponential, gamma, Weibull, and lognormal. In addition to this method, a power series expansion is derived using the integral equation for the second moment function M₂(t), when the first interarrival time has an exponential distribution.     

Efficient budget allocation strategies for elementary effects method in stochastic simulation

This paper focuses on extending the Morris' elementary effects method (MM) for sensitivity analysis/factor screening originated in the context of deterministic computer experiments to the stochastic simulation setting. Given a fixed simulation budget to expend, the main objective is to provide efficient and accurate estimates of main and interaction (or nonlinear) effects coined by the standard MM for characterizing the importance of each factor, despite the impact of simulation errors. Taking into account both the factor/input sampling uncertainty rooted in MM and the random errors inherent in a stochastic simulation, we develop efficient budget allocation strategies for implementing MM in this new context. Under each strategy proposed, we derive its corresponding optimal budget partition and optimal budget allocation rules. Numerical results corroborate the practical effectiveness of the proposed budget allocation strategies.     

Identifying the challenges to defence reform in Central and Eastern Europe: observations from the field

The authors have over 50 years' experience of working on defence in Central and Eastern Europe. They have been intimately involved in trying to reform over 10 national defence organisations including Ukraine. During this work, they often faced intractable resistance and scepticism or conversely, apparent unbounded support, but following this, a complete lack of any actual implementation work by officials. This paper addresses some of the findings and observations identified by the authors that appear to cause these responses and the consequent failure of reform. A new research approach has been taken by using the business and culture tools from Schein, Hofstede and Kotter to try and unravel the underlying causality of that failure. The second part of the paper produces a new process for change based upon the research conclusions to help other advisers and consultants working on reform in the post communist defence arena.     

基于μC／OS-Ⅱ和ARM的嵌入式系统功耗管理

为开发低功耗嵌入式系统和节约能源,分析了嵌入式系统的功耗来源及分类,提出了嵌入式系统的功耗设计方法,包括总体功耗设计、处理器选择、接口电路设计、电源供给电路设计以及动态电源管理等。基于以上方法,以μC／OS-Ⅱ和ARM LPC2131为研究平台,对上述功耗设计方法进行了实验验证。结果表明,采用合适的功耗设计,将大大降低嵌入式系统的功耗。     

4电平S类数字功放的电平合成策略

通过增加量化电平,Delta-Sigma调制器输出序列能够获得更好的调制性能。但在S类数字功放中,受限于开关功放的实现结构,多电平Delta-Sigma调制器输出脉冲序列无法直接驱动开关功放,需采用由多个开关功放单元构成的多电平开关功放。针对2比特Delta-Sigma调制器输出序列,分析了电平合成策略对4电平S类数字功放性能的影响,提出了两种优化的电平合成策略。理论分析和仿真结果表明,采用合适的电平合成策略,4电平S类数字功放可以获得更优的输出性能,尤其在输出功率回退状态下,电平合成策略对功放性能的影响更为显著。     

On Growing Operating Costs in the Armed Forces

Operating costs per unit of input or output are often claimed to grow faster in defence than elsewhere in the economy. In this paper, we outline several possible reasons as to why operating costs increase at higher rates in defence, including differences in the input factor mix and productivity growth, the technological complexity required to maintain the relative effect of weapon systems and a gradual reduction in the number of units and activity. We investigate whether operating costs grow at a faster rate than elsewhere in the economy, by estimating growth in real output unit costs in the Norwegian Armed Forces for the period 1994–2013, using activity as a measure of output. We find no increase beyond general inflation in structural (fixed) costs, whereas activity-based (variable) costs per unit of activity increase significantly.     

A nuclear-armed North Korea without ICBMs: the best achievable objective

This article analyzes the North Korean nuclear crisis from a balance-of-power perspective. It is in the long-term interests of international peace for a secure and independent North Korea to serve as a buffer between US and Chinese ground forces. However, the conventional military advantage of the South Korean-American alliance over North Korea has grown drastically since the end of the Cold War, threatening North Korea’s survival. Since North Korea lacks any reliable ally, nuclear weapons represent its most cost-effective way to restore a balance of power and thus secure itself. Accepting security guarantees in exchange for its nuclear arsenal is rhetorically appealing but not a viable approach. North Korea’s development of intercontinental ballistic missiles (ICBMs), however, has overcompensated for the post-Cold War imbalance, inviting talk in Washington of waging a preventive war. Persuading North Korea to give up its ICBM capability, not its nuclear arsenal, should therefore be the primary objective of US diplomacy.     

引入电流变化率的电源分布网络最差噪声分析算法

随着时钟频率的增加以及电源电压的降低,电源完整性问题日益凸显。将电流变化率加入到最差噪声算法的电流约束中,能够在任意电流变化率的情况下分析电源分布网络的最差噪声,从而获得更加真实的最差噪声。另外,利用改进的Knuth-Yao四边形不等式法对基于动态规划的最差噪声算法进行加速,加速后算法的时间复杂度从O(n~2m)降为O(mnlogn)。     

一项基于地方高校英语专业学生地方文化认知与输出能力的调查研究--以宁夏师范学院为例

服务地方经济社会发展是地方性本科院校的主要功能之一。本研究以宁夏师范学院英语专业学生为研究对象,探究该校英语专业学生服务地方经济社会发展能力,调查研究从学生地方文化认知和文化输出能力两个方面开展。研究结果显示该校英语专业学生宁南地方文化缺失现象严重,宁南地方文化的翻译沟通能力匮乏,文化输出能力偏低。研究发现学生服务地方经济社会发展能力偏低,并从人才培养方案的设置等方面提出了一些建议,以期能为该校英语专业学生服务地方经济社会发展能力的培养起到一定的积极作用。     

Evolutionary determinants of war

This paper considers evolutionarily stable decisions about whether to initiate violent conflict rather than accepting a peaceful sharing outcome. Focusing on small sets of players such as countries in a geographically confined area, we use the concept of evolutionary stability in finite populations. We find that players’ evolutionarily stable preferences widen the range of peaceful resource allocations that are rejected in favor of violent conflict, compared to the Nash equilibrium outcomes. Relative advantages in fighting strength are reflected in the equilibrium set of peaceful resource allocations.