Reliability of a single unit with k spares in case of the hyper-exponential and the erlang failure distribution

In this paper formulas are derived for the reliability of a single unit to which identical spares in standby are allocated, with all of these units having a hyper-exponential or Erlang distributed lifetime. Two advantages are obtained by using these distributions. First, the general procedure for calculating the effect of redundancy is applicable, in contrast with most of the common life distributions, such as Weibull. Moreover, both distributions are suitable for matching to observed curves and practical data by varying the values of the parameters, covering together most of the cases of practical interest.     

Optimal strategies for problems of simultaneous attack against an area defense with impact-point prediction

An area to be defended consists of separated point targets. These targets are subject to an attack in which the offensive weapons are assumed to arrive simultaneously. The defense has area defenders, each of which is capable of intercepting any attacker'. Furthermore, the defense has impact-point prediction, i.e., it has knowledge of each attacker's intended target prior to allocation of the area interceptors. For a given attack, the defense wishes to allocate its interceptors against attackers so as to maximize the expected total survival value of the targets. In its first move, the offense seeks an attack allocation which will minimize expected total surviving value against best defense. We develop an algorithm to determine optimal attack and defense strategies and the optimal value of this sequential min-max problem. Branch-and-bound techniques are used to obtain integer solutions, and illustrative computational results are provided.     

Cultural Conflict within Civil-Military Cooperation: A Case Study in Bosnia

In peace-support operations, employees of international humanitarian organisations often clash with those of the military. A lack of familiarity with each other's practices and values, embedded in their respective organisational cultures, is often seen as the culprit. This article presents and illustrates a road map to manage such cultural differences between cooperating organisations. We found that the military culture, in our Bosnian case study, was seen to operate as a hierarchical culture (characterised by formalisation, stability, predictability and efficiency). The culture of international humanitarian organisations, on the other hand, was depicted as clan-type (characterised by teamwork, participation and consensus). To facilitate the creation of cultural awareness as well as respect for, and reconciliation of, cultural differences we recommend several concrete actions that could improve civil-military cooperation.     

确定车削加工工艺系统刚度的一种实验方法

将工艺系统的弹性变形看成是由平移和弯曲两种变形构成,利用阶梯形工件,可以确定工艺系统的等效刚度。从而为合理地选择加工参数、保证加工质量提供必要的条件。     

Optimal nonmyopic gambling strategy for the generalized Kelly criterion

We consider the optimal wagers to be made by a gambler who starts with a given initial wealth. The gambler faces a sequence of two-outcome games, i.e., “win” vs. “lose,” and wishes to maximize the expected value of his terminal utility. It has been shown by Kelly, Bellman, and others that if the terminal utility is of the form log x, where x is the terminal wealth, then the optimal policy is myopic, i.e., the optimal wager is always to bet a constant fraction of the wealth provided that the probability of winning exceeds the probability of losing. In this paper we provide a critique of the simple logarithmic assumption for the utility of terminal wealth and solve the problem with a more general utility function. We show that in the general case, the optimal policy is not myopic, and we provide analytic expressions for optimal wager decisions in terms of the problem parameters. We also provide conditions under which the optimal policy reduces to the simple myopic case. © 1997 John Wiley & Sons, Inc. Naval Research Logistics 44: 639–654, 1997     

Planning versus Chaos in Clausewitz's On War

Clausewitz laid great emphasis on the planned construction of war, but this idea has received little attention from his commentators, who generally attach far greater importance to what he said about the chaotic elements of war, in particular its interactive nature and the friction inseparable from its conduct. This article gives long-overdue recognition to planning as a dominant theme of On War. The essential point Clausewitz makes concerning interaction is not that the enemy's responses are bound to disrupt our plans, but that our plans must aim to predict and incorporate his responses. Clausewitz acknowledges that friction creates enormous difficulties for the realization of any plan, but it is precisely in respect of this challenge that he develops the concept of military genius, whose capabilities are seen above all as the executive arm of planning.     

TRENDS AND MARKERS

The twin concepts of secrecy and transparency are central to any discourse on the freeness and fairness of elections, because they are universally accep ted yardsticks of the degree to which elections can be said to be legitimate. Without challenging this truism, this paper explores these concepts as both theoretical constructs and as manifes ted in empirical situations. It will highlight their ideological function and argue that they have an alienating effect in practice. The article will also attempt to show how secrecy and transparency have helped to shape Lesotho's electoral process and the mode of its management, and will also discuss the issues and questions that it raises. Next, the most critical issues in any debate concerning Lesotho's elections and their management are raised, followed by the recommendation of an ideal way of managing elections to serve the interest of voters better. Lastly, the paper demonstrates the danger of depoliticising elections and relegating them to the legal sphere, which only the courts of law are competent to interpret.