Discrete equal‐capacity p‐median problem

This paper examines the discrete equal‐capacity p‐median problem that seeks to locate p new facilities (medians) on a network, each having a given uniform capacity, in order to minimize the sum of distribution costs while satisfying the demand on the network. Such problems arise, for example, in local access and transport area telecommunication network design problems where any number of a set of p facility units can be constructed at the specified candidate sites (hence, the net capacity is an integer multiple of a given unit capacity). We develop various valid inequalities, a separation routine for generating cutting planes that are specific members of such inequalities, as well as an enhanced reformulation that constructs a partial convex hull representation that subsumes an entire class of valid inequalities via its linear programming relaxation. We also propose suitable heuristic schemes for this problem, based on sequentially rounding the continuous relaxation solutions obtained for the various equivalent formulations of the problem. Extensive computational results are provided to demonstrate the effectiveness of the proposed valid inequalities, enhanced formulations, and heuristic schemes. The results indicate that the proposed schemes for tightening the underlying relaxations play a significant role in enhancing the performance of both exact and heuristic solution methods for this class of problems. © 2000 John & Sons, Inc. Naval Research Logistics 47: 166–183, 2000.     

基于Floyd算法的常规导弹连续波次作战运输规划

为提高常规导弹连续波次作战效能,对常规导弹连续波次作战运输规划问题进行研究。以Floyd算法为基础,首先生成了作战机动区域的交通网络最短路径、距离矩阵;其次将常规导弹连续波次作战运输过程分解为不同阶段,以运输过程中的整体暴露时间最短为目标,构建了初始规划方案0-1整数规划模型;然后考虑道路通行量及地域容量限制,对初始规划方案中存在的地域容量超过限制及单行道路中会车、超车情况进行逐步循环优化,以得到最佳运输规划方案;最后选择了一个作战案例想定,通过Matlab编程对案例进行了求解,得到了针对此案例的最佳运输规划方案,验证了模型的正确性和算法的有效性。     

Dirty war: chemical weapon use and domestic repression

The utilization of chemical weapons to quash domestic rebellion is a drastic action for a regime facing domestic challengers to take, especially given the reputation costs and risk of international intervention. However, recent developments have illustrated that some regimes have contemplated and implemented extraordinary measures (including the use of chemical munitions) to quash rebellion. This study addresses the question of why some states utilize chemical weapons against domestic challengers while others refrain from this level of state repression. I argue that the utilization of chemical weapons has both domestic and international elements. Specifically, that ethnic cleavages that lead to secessionist challenges and factors associated with inter-state rivalry impact the likelihood that a state utilizes the employment of chemical munitions. I test my argument and other explanations regarding repression with a casestudy approach utilizing captured Iraqi Government documents comparing Iraq’s Al-Anfal campaigns with developments during the recent Syrian Civil War.     

Rethinking military behavior during the Arab Spring

Why did some Arab militaries remain loyal to authoritarian rulers amid mass uprisings during the Arab Spring while others defected to the opposition? One popular explanation shows this variation with reference to the degree of military institutionalization: institutionalized militaries defected, while patrimonial militaries remained loyal. This article argues that the institutionalization hypothesis does not provide a complete account of the mechanisms through which the degree of military institutionalization leads to either defection or continued loyalty. This shortcoming stems from the fact that scholars have treated military institutionalization as a catch-all concept for three distinct variables: ethnic stacking of the military, patronage distribution, and organizational factionalization. Examining the interaction between these variables highlights the mechanisms through which military defection occurs, and therefore that disaggregating institutionalization into its component parts provides a more complete explanation of military behavior during the Arab Spring.     

Revisiting the rise and fall of the Somali Armed Forces, 1960–2012

The history of the Somali Armed Forces, principally the army, forms an important part of studying the Somali civil war. Two key themes are evident from 1960: the pursuit of an irredentist agenda beyond reasonable limits, which led to the downfall of Siad Barre’s regime, and the clan divisions and agendas that Barre used to shore up his rule in the 1980s and that have bedeviled the rebirth of the Somali Army in the twenty-first century. With the twentieth-century context covered, and in some places reinterpreted, this article then focuses on the uncertain rebirth of the Somali Armed Forces since 2008, using a host of primary and United Nations official sources. Assistance efforts have been focused on Mogadishu, but limited success has been made in forming truly national armed forces. Future prospects are uncertain, but there are some signs of hope.     

军队科研机构推进国防知识产权转化运用

军队科研机构作为国家科技创新体系的重要组成部分,承担了大量科技创新任务,产生了许多具有自主知识产权的高水平科技成果,推动军队科研机构国防知识产权转化运用,是贯彻军民融合发展战略的必要途径。分析了军队科研机构国防知识产权转化的现状及制约转化的现实障碍,并结合实际探讨了推进军队科研机构国防知识产权转化的建议举措。     

大容量数据下基于DTN的链路中断优化传输技术

激光或GHz以上的高频链路的应用将导致DTN(Delay Tolerant Network)网络链路数据容量的增大,大容量数据链路的间歇性中断将严重影响数据的传输效率。针对DTN网络中大容量数据链路频繁中断和节点的剩余缓存空间剧烈变化的问题,提出在DTN路由算法上增加拥塞状态预测机制和易中断链路判定机制,根据节点的拥塞程度定义惩罚函数,缓解链路中断和节点资源受限导致的拥塞。仿真结果表明,该机制可以有效提高DTN网络的传输性能。     

基于事故树和贝叶斯的军民航飞行冲突风险研究

为充分了解当前军民航飞行冲突、危险接近事故征候的成因,并对其发生原因进行有重点的预防和对事件发生概率的精确预测,首先建立事故树模型,对其原因进行分析;总结导致其发生的基本事件,计算事故树模型的最小割集和各个基本事件的结构重要度;其次对军民航飞行冲突、危险接近事故征候的发生概率进行合理的取值,得出基本事件的概率重要度,指出基本事件发生概率对顶事件发生概率的影响;最后构建军民航飞行冲突、危险接近事故征候贝叶斯网络模型,计算中间事件的条件概率和顶事件发生概率,并与实际结果进行对比,验证方法可行性。     

Humanitarian response to hurricane disasters: Coordinating flood‐risk mitigation with fundraising and relief operations

To alleviate flooding, caused by hurricanes, governments build structural barriers called levees. In addition, relief providers such as the nongovernmental organizations and charities raise funds, and procure and deliver supplies (food, water, and medicines) for humanitarian relief. The strategy for managing disasters must, therefore, weigh the costs and benefits of building levees as well as procuring and delivering supplies. We use a three‐stage decision making framework to study how the investment in levee capacity can be integrated with supply procurements, fundraising, and rapid response. One of our major findings is that a large fundraising cost discourages postdisaster funding, implying relatively large investments in levee and prepositioned supplies. That notwithstanding, a large social value (of saving life) can tilt the balance in favor of postdisaster funding. If the levee capacity increases, funding for predisaster procurement is reduced without affecting postdisaster funding. For a sufficiently large increase in capacity, however, postdisaster response becomes superfluous. We also find that hurricane uncertainty motivates levees with large capacity. In contrast, levee‐failures motivate levees with small capacity.     

新形势下军队军事计量培训建设

随着我军信息化建设的不断发展,军事计量在装备全系统、全寿命、全过程监管中发挥着越来越重要的作用。武器装备信息化程度越高,越需要严苛的计量保障体系,而计量人员是军事计量保障工作的主体,所以,加强我军军事计量人员的培训工作,具有非常重要的意义。本文通过对地方计量人员培训体系进行分析,利用军地融合方式,研究我军军事计量培训工作在新时期新阶段的发展思路。