Multivariate dependent relevations with applications,and related topics

“Relevation” is the name given by Krakowski to the distribution of failure time of a replacement from an aging stock. The present authors have extended this concept to include (i) hierarchal replacement systems and (ii) dependence between lifetimes of original and replacement items. In this article, we present some further developments, including first steps toward a synthesis of (i) and (ii).     

Service levels in distribution systems with random customer order size

An approximate method for measuring the service levels of the warehouse-retailer system operating under (s, S) policy is presented. All the retailers are identical and the demand process at each retailer follows a stationary stuttering Poisson process. This type of demand process allows customer orders to be for a random number of units, which gives rise to the undershoot quantity at both the warehouse and retailer levels. Exact analyses of the distribution of the undershoot quantity and the number of orders place by a retailer during the warehouse reordering lead time are derived. By using this distribution together with probability approximation and other heuristic approaches, we model the behavior of the warehouse level. Based on the results of the warehouse level and on an existing framework from previous work, the service level at the retailer level is estimated. Results of the approximate method are then compared with those of simulation. © 1995 John Wiley & Sons, Inc.     

Optimal empty vehicle redistribution for hub‐and‐spoke transportation systems

This article considers the empty vehicle redistribution problem in a hub‐and‐spoke transportation system, with random demands and stochastic transportation times. An event‐driven model is formulated, which yields the implicit optimal control policy. Based on the analytical results for two‐depot systems, a dynamic decomposition procedure is presented which produces a near‐optimal policy with linear computational complexity in terms of the number of spokes. The resulting policy has the same asymptotic behavior as that of the optimal policy. It is found that the threshold‐type control policy is not usually optimal in such systems. The results are illustrated through small‐scale numerical examples. Through simulation the robustness of the dynamic decomposition policy is tested using a variety of scenarios: more spokes, more vehicles, different combinations of distribution types for the empty vehicle travel times and loaded vehicle arrivals. This shows that the dynamic decomposition policy is significantly better than a heuristics policy in all scenarios and appears to be robust to the assumptions of the distribution types. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

The politics of renewed quest for a Biafra Republic in Nigeria

The quest for a Biafran Republic by the Igbo ethnic group has become a recurring demand in Nigeria since the late 1960s. The agitation has been premised on claims of marginalisation and exclusion of the Igbo people in the Nigerian body politic. In spite of the consistency of the agitation through various Administrations, there was a noticeable lull in such demands during the time of President Goodluck Jonathan, only to assume a frightening proportion since the advent of the Administration of President Muhammadu Buhari. This article locates the factors in the outcomes of the 2015 general elections: the question of inclusion and representation; the unfinished nature of the Nigerian civil war; economic challenges, miscalculation both on the part of the Igbo people and indiscretion in the initial appointments made by President Muhammadu Buhari. The article recommends political restructuring of Nigeria as one of the ways to address secessionist tendencies.     

ON RATIONAL CHOICE THEORY AND THE STUDY OF TERRORISM

When rational choice theory is applied to the study of terrorism, it is important that attention be given to the derived principles of constrained utility maximization. Particularly useful is the Slutsky equation, which rigorously analyzes the quantity response in one activity to a price change in another. By directing attention to assumptions and/or information about compensated cross price elasticities, expenditure shares, and income elasticities, the Slutsky equation can provide critical guidance in both theoretical and empirical analysis.     

CREATING SUNS ON EARTH

Concerns about climate change and energy security have prompted some countries to revive dormant nuclear fission power programs to meet growing energy demands and reduce carbon dioxide emissions. However, this so-called nuclear renaissance based on fission would have major drawbacks in the areas of safety, security, and nonproliferation. Nuclear fusion, however, is portrayed by its proponents as mitigating these drawbacks, and scientists continue to pursue fusion's promise with two large-scale projects: the International Thermonuclear Experimental Reactor (ITER), and the Laser Inertial Fusion Engine (LIFE) reactor. Although supporters often hail fusion as proliferation resistant, the technology could be used to create weapons-usable fissile material. This article explains how fissile material could be created in ITER or LIFE and analyzes other nonproliferation implications of fusion; the authors discuss the various challenges faced by ITER and LIFE.     

Signaling resolve,democratization, and the first battle of Fallujah

Perceptions and efforts to signal resolve can play an important role in counterinsurgency. The Coalition offensive against Fallujah in April 2004 demonstrates the limitations of relying on military force to signal resolve. The offensive catalyzed insurgent violence in Iraq and generated popular support for the insurgency. The Coalition prematurely halted the offensive because the Iraqi Governing Council (IGC) could not maintain support for the Coalition in the face of popular outrage. Given the importance of democratizing Iraq and establishing a sovereign government, the objections of the IGC could not be ignored. Without Iraqi political support, military force ultimately signaled weakness instead of resolve.     

Some distributions arising as a consequence of errors in inspection

In this article, the authors survey and consolidate their investigations during the years 1980-1983 dealing with consequences of errors in inspection sampling models. Some indication of the current and future research is given.     

Landmarks in defense literature

The Power of Personality in War. By Major General Baron Hugo von Freytag-Lorighoven, Military Service Publishing Company, Harrisburg, PA (1955)