Bilateral phase-type distributions

In this article we define a class of distributions called bilateral phase type (BPH), and study its closure and computational properties. The class of BPH distributions is closed under convolution, negative convolution, and mixtures. The one-sided version of BPH, called generalized phase type (GPH), is also defined. The class of GPH distributions is strictly larger than the class of phase-type distributions introduced by Neuts, and is closed under convolution, negative convolution with nonnegativity condition, mixtures, and formation of coherent systems. We give computational schemes to compute the resulting distributions from the above operations and extend them to analyze queueing processes. In particular, we present efficient algorithms to compute the steady-state and transient waiting times in GPH/GPH/1 queues and a simple algorithm to compute the steady-state waiting time in M/GPH/1 queues.     

On failure modeling

A promising approach to failure modeling, in particular to developing failure-time distributions, is discussed. Under this approach, system state or wear and tear is modeled by an appropriately chosen random process—for example, a diffusion process—and the occurrences of fatal shocks are modeled by a Poisson process whose rate function is state dependent. The system is said to fail when either wear and tear accumulates beyond an acceptable or safe level or a fatal shock occurs. This approach has significant merit. First, it provides revealing new insights into most of the famous and frequently used lifetime distributions in reliability theory. Moreover, it suggests intuitively appealing ways for enhancing those standard models. Indeed, this approach provides a means of representing the underlying dynamics inherent in failure processes. Reasonable postulates for the dynamics of failure should lend credence to the prediction and estimation of reliability, maintainability, and availability. In other words, accuracy of representation could lead to better, more reliable prediction of failure.     

De-Constructing the French Wars: Napoleon as Anti-Strategist

The Emperor Napoleon I is regarded as one of the greatest generals of all time and, as such, he has attracted an immense bibliography. In spite of this, there have been few studies of him as a strategist: instead, it is simply assumed that it was enough for the Emperor to have conducted an operation for it to have had a logical strategic goal. In this article, however, Napoleon is shown to have been primarily an opportunist, who was frequently guided by the needs of the moment and swayed from his course by circumstance, while it is further suggested that, even considered on their own merits, many of his decisions were faulty in the extreme.     

International Involvement in Restructuring and Creating Security Forces: The Case of Haiti

The controversy over banning landmines in the past decade has removed matters of military technical expertise to the purview of civilian interest groups. According to a Huntingtonian perspective, this could be an indicator of unhealthy civil-military relations. Evidence of this includes political leaders' disregard of senior military advice and the initiation of a program to develop landmine alternatives after having already committed to banning them. The desire to ban landmines may represent a pragmatic revision of pacifist attempts to ban warfare altogether. Because of the development of self-destructing or deactivating mines, the landmine ban movement intrudes on technical military matters without redeeming humanitarian value. This intrusion may have further ramifications for civil-military relations.     

Traitor or patriot? Andrey Vlasov and the Russian liberation movement 1942–45

Catherine Andreyev, Vlasov and the Russian Liberation Movement: Soviet Reality and Emigre Theories. Cambridge: Cambridge University Press, 1987. Pp.251; $34.50.

Sergej Froehlich, General Wlassow: Russen und Deutsche zwischen Hitler und Stalin (revised and edited by Edel von Freier). Koeln: Markus Verlag, 1987. Pp.403; DM.39.80.

Joachim Hoffmann, Die Geschichte der Wlassow‐Armes. Freiburg: Verlag Rombach, 1986. Pp.468; DM32.