Inventory sharing under decentralized preventive transshipments

We consider preventive transshipments between two stores in a decentralized system with two demand subperiods. Replenishment orders are made before the first subperiod, and the stores may make transshipments to one another between the subperiods. We prove that the transshipment decision has a dominant strategy, called a control‐band conserving transfer policy, under which each store chooses a quantity to transship in or out that will keep its second‐subperiod starting inventory level within a range called a control band. We prove that the optimal replenishment policy is a threshold policy in which the threshold depends on the capacity level at the other store. Finally, we prove that there does not exist a transfer price that coordinates the decentralized supply chain. Our research also explains many of the differences between preventive and emergency transshipments, including differences in the optimal transfer policies and the existence or nonexistence of transfer prices that coordinate the system. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

The logistic–exponential survival distribution

For various parameter combinations, the logistic–exponential survival distribution belongs to four common classes of survival distributions: increasing failure rate, decreasing failure rate, bathtub‐shaped failure rate, and upside‐down bathtub‐shaped failure rate. Graphical comparison of this new distribution with other common survival distributions is seen in a plot of the skewness versus the coefficient of variation. The distribution can be used as a survival model or as a device to determine the distribution class from which a particular data set is drawn. As the three‐parameter version is less mathematically tractable, our major results concern the two‐parameter version. Boundaries for the maximum likelihood estimators of the parameters are derived in this article. Also, a fixed‐point method to find the maximum likelihood estimators for complete and censored data sets has been developed. The two‐parameter and the three‐parameter versions of the logistic–exponential distribution are applied to two real‐life data sets. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

Analysis of a finite‐buffer bulk‐service queue with discrete‐Markovian arrival process: D‐MAP/Ga,b/1/N

Discrete‐time queues with D‐MAP arrival process are more useful in modeling and performance analysis of telecommunication networks based on the ATM environment. This paper analyzes a finite‐buffer discrete‐time queue with general bulk‐service rule, wherein the arrival process is D‐MAP and service times are arbitrarily and independently distributed. The distributions of buffer contents at various epochs (departure, random, and prearrival) have been obtained using imbedded Markov chain and supplementary variable methods. Finally, some performance measures such as loss probability and average delay are discussed. Numerical results are also presented in some cases. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 345–363, 2003.     

UNFPA and population assistance

International population assistance in the UN is a relatively recent development; it is only since 1966 that a broad-based technical assistance program in population was authorized by the General Assembly. The desire of developing country members for accelerated economic growth ultimately brought about a change in the views on population. In 1967, the Secretary General established a trust fund for population activities, later renamed the United Nations Fund for Population Activities (UNFPA). 3 principles have guided UNFPA work since its inception: 1) national sovereignty in population matters is to be resspected and adhered to at all times, 2) individuals and couples are to be provided the information and services necessary to determine freely and responsibly the number and spacing of their children, and 3) population goals and policies are integral parts of socioeconomic defelopment. The areas of assistance by the UNFPA consist of 1) family planning, 2) communication and education, 3) population dynamics, 4) basic data collection, 5) population policy formulation and implementation, and 6) special programs such as those for women and the aging population. In 16 years, the UNFPA has received about $1.4 billion for transfer to developing countries as population assistanceand has financed 4373 population projects in 149 countries and territories. The relation between the US government and UNFPA is tenuous and likely to remain so as long as the US cannot resolve its own domestic controversies over famly planning, foreign population assistance, abortion, which, ironically, is legalin the country. There will always be some sort of domestic controversy over population; the UN has overcome domestic difficulties by framing the arguments properly within the demographic, social, economic, ecological, and political concerns of countries and applying the fundamental principles of national sovereignty, freedom of individual choice, and the link of population and development,to reconcile differences.     

Test for the extreme value and weibull distributions based on normalized spacings

Discussed in this article are tests for the extreme-value distribution, or, equivalently, for the two-parameter Weibull distribution when parameters are unknown and the sample may be censored. The three tests investigated are based on the median, the mean, and the Anderson-Darling A² statistic calculated from a set zⁱ of values derived from the spacings of the sample. The median and the mean have previously been discussed by Mann, Scheuer, and Fertig [10] and by Tiku and Singh [14]. Asymptotic distributions and points are given for the test statistics, based on recently developed theory, and power studies are conducted to compare them with each other and with two other statistics suitable for the test. Of the normalized spacings tests, A² is recommended overall; the mean also gives good power in many situations, but can be nonconsistent.     

Optimal replacement for fault-tolerant systems

We consider the optimal replacement problem for a fault tolerant system comprised of N components. The components are distingushable, and the state of the system is given by knowing exactly which components are operationl and which have failed. The individual component failure rates depend on the state of the entire system. We assume that the rate at which the system produces income decreases as the system deteriorates and the system replacement cost rises. Individual components cannot be replaced. We give a greedy-type algorithm that produces the replacement policy that maximizes the long-run net system income per unit time.     

Book reviews

Die Faszination des Verrats: Eine Studie zur Dekadenz im Ost‐West Konflikt. By Thomas Noetzel. Hamburg, Junius (1989) DM48.

Les Nations Armées. By Maurice Faivre (Preface by Pierre Messmer), Paris FEDN/Economica (1988).

Insurgency and Terrorism: Inside Modern Revolutionary Warfare. By Bard E. O'Neill, Brassey's (US), Washington, DC (1990), $19.00.

LIC 2010: Special Operations and Unconventional Warfare in the Next Century. By Rod Paschall, Brassey's (US), Washington, DC, $24.00.

Air Power and Colonial Conflict: The Royal Air Force 1919–1939. By D. E. Omissi, Manchester University Press, Manchester and New York (1990), ISBN 0–7190–2960–0. £35.00.

Key to the Sinai: The Battles for Abu Ageila in the 1956 and 1967 Arab‐Israeli Wars. By George W. Gawrych. Combat Studies Institute Research Survey No. 7, US Army Command and General Staff College, Fort Leavenworth, Kansas, 1990. $8.00.

Arms Export Regulations. Edited by Ian Anthony. SIPRI/Oxford University Press, Oxford (1991), ISBN 0–19–829158–2, £25.00.     

Armed services recruiting research: Issues,findings, and needs

Manning the nation's armed services will continue to be a crucial issue for the remainder of the 1980s. With the projected growth of the services during this decade, the downturn in the 17–21-year-old male population, and the possible upturn in the economy, the ability of the services to meet their respective quality and quantity recruiting goals becomes of central concern. The accurate estimation of the supply for various types of recruits becomes especially important when one views the nearly $1 billion budgeted annually for recruiting and the impact that any military pay raises can have on the DOD's manpower costs of over $40 billion annually. In addition, perceived difficulties in recruiting can impact on weapon systems design decisions, authorized manning levels, and exacerbate the debate concerning the draft; hence, it is clear that few issues today warrant more attention than improving the efficiency and effectiveness of military recruiting. This article provides an introduction and review of some of the key issues involved in modeling and estimating the supply of military recruits. It summarizes and compares the findings of selected econometric models, all of which are based on enlistment experience since the introduction of the All-Volunteer Force in 1973. It also presents some new insights and directions for research dealing with simultaneity, validation, generation of rigorous confidence intervals, and data base selection. It concludes by listing some of the research needs to be addressed in the future.