Cost analysis of warranty policies

This article analyzes two general warranty policies involving an initial free replacement period, followed by a pro rata period. We examine the short-run total costs and longrun average costs under these policies. Formulas for both consumer costs and manufacturer profits under warranty are derived. We also study the expected number of purchases over the product life cycle under both policies. Bounds for the expected total costs and expected number of purchases are obtained for the case where the failure distribution of the item is new better than used.     

Building the Somali National Army: Anatomy of a failure, 2008–2018

ABSTRACT

Over a decade of security force assistance (SFA) initiatives to build an effective Somali National Army (SNA) failed because of the interrelated effects of political, contextual and operational challenges. The key political challenges were interest asymmetry between international actors and Somali elites, insufficient focus on institution-building and a lack of donor coordination. The principal contextual challenges in Somalia were the legacies of two decades of state collapse and the negative effects of clan dynamics. The main operational challenges were building an army while simultaneously fighting a war, the complexities of military integration, and the severe capability gaps afflicting the SNA.     

General Zuo’s counter-insurgency doctrine

ABSTRACT

This paper examines the career of one of the most notable of Chinese state officials in the mid-nineteenth century, General Zuo Zongtang (1812–1885) at a time when the Qing Empire was beset by enemies on all sides along with the massive Taiping Rebellion (1851–65). The paper explores how Zuo created a coherent and flexible counter-insurgency doctrine that underpinned his suppression of the Taipings, the Nian, Muslim rebels of the northwest and the defeat of a massive Sufi revolt in Central Asia. The paper also shows how Zuo helped convince the Russians to return territory they occupied in Central Asia, thereby preserving the territorial integrity of the Qing Empire in the region.     

Level product form QSF processes and an analysis of queues with Coxian interarrival distribution

In this article, we study a class of Quasi‐Skipfree (QSF) processes where the transition rate submatrices in the skipfree direction have a column times row structure. Under homogeneity and irreducibility assumptions we show that the stationary distributions of these processes have a product form as a function of the level. For an application, we will discuss the ‐queue that can be modeled as a QSF process on a two‐dimensional state space. In addition, we study the properties of the stationary distribution and derive monotonicity of the mean number of the customers in the queue, their mean sojourn time and the variance as a function of for fixed mean arrival rate. © 2016 Wiley Periodicals, Inc. Naval Research Logisticsxs 66:57–72, 2019