An exact analysis of a joint production‐inventory problem in two‐echelon inventory systems

We consider a two‐echelon inventory system with a manufacturer operating from a warehouse supplying multiple distribution centers (DCs) that satisfy the demand originating from multiple sources. The manufacturer has a finite production capacity and production times are stochastic. Demand from each source follows an independent Poisson process. We assume that the transportation times between the warehouse and DCs may be positive which may require keeping inventory at both the warehouse and DCs. Inventory in both echelons is managed using the base‐stock policy. Each demand source can procure the product from one or more DCs, each incurring a different fulfilment cost. The objective is to determine the optimal base‐stock levels at the warehouse and DCs as well as the assignment of the demand sources to the DCs so that the sum of inventory holding, backlog, and transportation costs is minimized. We obtain a simple equation for finding the optimal base‐stock level at each DC and an upper bound for the optimal base‐stock level at the warehouse. We demonstrate several managerial insights including that the demand from each source is optimally fulfilled entirely from a single distribution center, and as the system's utilization approaches 1, the optimal base‐stock level increases in the transportation time at a rate equal to the demand rate arriving at the DC. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011     

A sampling procedure and public policy

This paper describes the background of the Office of Management Budget Circular A-21, “Principles for Determining Costs Applicable to Grants, Contracts, and Other Agreements with Educational Institutions,” that describes the requirement for effort reporting. A sampling procedure is proposed as an alternative to 100% reporting.     

Financial versus human resources in the Greek‐Turkish arms race: A forecasting investigation using artificial neural networks

This paper aims at forecasting the burden on the Greek economy resulting from the arms race against Turkey and at concentrating on the leading determinants of this burden. The military debt and the defence share of GDP are employed alternatively in order to approximate the measurement of the arms race pressure on Greece, and the method used is that of artificial neural networks. The use of a wide variety of explanatory variables in combination with the promising results derived, suggest that the impact on the Greek economy resulting from this arms race is determined, to a large, extent, by demographic factors which strongly favour the Turkish side. Prediction on both miltary debt and defence expenditure exhibited highly satisfactory accuracy, while the estimation of input significance, indicates that variables describing the Turkish side are often dominant over the corresponding Greek ones.     

Uncovering foreign military innovation

An analysis of US assessments of Germany's development of armored warfare illustrates the problems that intelligence agencies face as they attempt to understand military innovation. The covert nature of German Army's tank research in the years immediately following World War I limited the number of indicators of Berlin's interest in armored warfare. Similarly, the United States possessed at best a fragmentary picture of German experimentation with armor. By the outbreak of World War II, however, US military attaches had nonetheless developed an accurate understanding of German concepts of armored warfare. If the United States is to avoid strategic surprise in the future, it must cultivate intelligence sources and employ considerably different methods from those of the Cold War.     

PEACE PROCESSES AND CONFLICT RESOLUTION IN THE HORN OF AFRICA

Conflict resolution processes must meet certain prerequisites and conditions. Unless the warring parties or the mediators meet, it will be difficult to find lasting and just solutions to the conflicts in the Horn (Djibouti, Eritrea and Ethiopia, and Somalia). Most of these conflicts have ethnic or religious components and also have a lot do with the nature of the government institutions and the power distribution among the communities within these states. Identifying the main causes of the conflict and the issues involved in each country is a very necessary first step toward peace. Secondly, conditions have to be identified that would make the current peace agreements work. This includes identifying the specific problems faced by the parties involved; ascertaining the validity of the mechanisms through which the problems will be overcome; and planning how the agreements will be maintained. The knowledge that mediators have about the conflict is often as important as the actual meeting of parties at the negotiation table. This article also evaluates the peace initiatives underway in the Horn and attempts to identify the apparent reasons that prevented their implementation.     

Compromise allocation in multivariate stratified sampling: An integer solution

The problem of determining the sample sizes in various strata when several characteristics are under study is formulated as a nonlinear multistage decision problem. Dynamic programming is used to obtain an integer solution to the problem. © 1997 John Wiley & Sons, Inc.     

Inventory management with advance capacity information

An important aspect of supply chain management is dealing with demand and supply uncertainty. The uncertainty of future supply can be reduced if a company is able to obtain advance capacity information (ACI) about future supply/production capacity availability from its supplier. We address a periodic‐review inventory system under stochastic demand and stochastic limited supply, for which ACI is available. We show that the optimal ordering policy is a state‐dependent base‐stock policy characterized by a base‐stock level that is a function of ACI. We establish a link with inventory models that use advance demand information (ADI) by developing a capacitated inventory system with ADI, and we show that equivalence can only be set under a very specific and restrictive assumption, implying that ADI insights will not necessarily hold in the ACI environment. Our numerical results reveal several managerial insights. In particular, we show that ACI is most beneficial when there is sufficient flexibility to react to anticipated demand and supply capacity mismatches. Further, most of the benefits can be achieved with only limited future visibility. We also show that the system parameters affecting the value of ACI interact in a complex way and therefore need to be considered in an integrated manner. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011