Finding optimal policies in the (S - 1, S ) lost sales inventory model with multiple demand classes

This paper examines the algorithms proposed in the literature forfinding good critical level policies in the (S-1,S) lost salesinventory model with multiple demand classes. Our main result isthat we establish guaranteed optimality for two of thesealgorithms. This result is extended to different resupplyassumptions, such as a single server queue. As a corollary, weprovide an alternative proof of the optimality of critical levelpolicies among the class of all policies.inventory;customer differentiation;multiple demand classes;rationing lost sales;stochastic dynamic programming

Firm Heterogeneity, Internal Finance, and `Credit Rationing'

Assessing the extent to which agents or firms face capital-market imperfections and quantity restrictions on credit is crucial for measuring intertemporal tradeoffs in consumption or the cost of capital for investment. In contrast to standard price-clearing, "full-information" models of loan markets, in models of credit allocation where information is imperfect (which we describe as "information-intensive"). "the interest rate" need not reflect the shadow price of credit in financial intermediation. Credit rationing to some borrowers is likely. In actual markets, many loan contracts are offered, both "full-information" and "information intensive." Our focus in this paper is on firm heterogeneity in credit markets; we analyze mechanisms by which credit markets sort borrowers in the presence of differing degrees of asymmetric information; we emphasize the potential for credit rationing in equilibrium and the response of credit allocation to borrower-specific shocks. Our approach suggests that external finance will be differentially available to entrepreneurs --holding constant their project opportunities -- according to their internal net worth position. That is, there is an important link for many firms between internal finance and investment spending. We develop a simple general equilibrium model of credit allocation, in which different loan contracts are offered to different types of borrowers. The extent to which different borrowers can obtain credit depends on the distribution of internal finance, aggregate net worth levels, and whether projects are observable. While credit restrictions to some classes of borrowers are a feature of a multiple-contract equilibrium, the severity can vary substantially in response to financial disturbances. We consider shocks to borrowers' net worth. Credit restrictions may occur in response to a deterioration of net-worth positions., A "credit collapse," in which no loans are offered to certain types of borrowers is possible. Investment and financing decisions are not, in general independent. We discuss implications for tax policy and for public policy toward financial institutions.

Using imperfect advance demand information in ordering and rationing decisions

Cataloged from PDF version of article.In this paper, we consider an inventory problem with two demand classes having different priorities. The appropriate policy of rationing the available stock, i.e. reserving some stock for meeting prospective future demand of preferred customers at the expense of deliberately losing some of the currently materialized demand of lower demand class(es), relies on the estimation of the future demand. Utilizing current signals on future demand, which we refer to as imperfect advance demand information (ADI), decreases uncertainty on future demand and may help to make better decisions on when to start rejecting lower class demand. We develop a model that incorporates imperfect ADI with inventory ordering (replenishment) decision and rationing available stock. In a two-period setting, we show some structural properties, solve the rationing problem, and propose solution methods based on Monte Carlo simulation for the ordering problem. We conduct numerical tests to measure the impact of system parameters on the expected value of imperfect ADI, and provide useful managerial insights. (C) 2009 Elsevier B.V. All rights reserved

E-Fulfillment and Multi-Channel Distribution – A Review

This review addresses the specific supply chain management issues of Internet fulfillment in a multi-channel environment. It provides a systematic overview of managerial planning tasks and reviews corresponding quantitative models. In this way, we aim to enhance the understanding of multi-channel e-fulfillment and to identify gaps between relevant managerial issues and academic literature, thereby indicating directions for future research. One of the recurrent patterns in today’s e-commerce operations is the combination of ‘bricks-and-clicks’, the integration of e-fulfillment into a portfolio of multiple alternative distribution channels. From a supply chain management perspective, multi-channel distribution provides opportunities for serving different customer segments, creating synergies, and exploiting economies of scale. However, in order to successfully exploit these opportunities companies need to master novel challenges. In particular, the design of a multi-channel distribution system requires a constant trade-off between process integration and separation across multiple channels. In addition, sales and operations decisions are ever more tightly intertwined as delivery and after-sales services are becoming key components of the product offering.Distribution;E-fulfillment;Literature Review;Online Retailing

Finding optimal policies in the (S - 1, S ) lost sales inventory model with multiple demand classes

This paper examines the algorithms proposed in the literature for finding good critical level policies in the (S-1,S) lost sales inventory model with multiple demand classes. Our main result is that we establish guaranteed optimality for two of these algorithms. This result is extended to different resupply assumptions, such as a single server queue. As a corollary, we provide an alternative proof of the optimality of critical level policies among the class of all policies

Customer Differentiated End-of-Life Inventory Problem

This paper deals with the service parts end-of-life inventory problem in a circumstance that demands for service parts are differentiated. Customer differentiation might be due to criticality of the demand or based on various service contracts. In both cases, we model the problem as a finite horizon stochastic dynamic program and characterize the structure of the optimal policy. We show that when customers are differentiated based on the demand criticality then the optimal structure consists of time and state dependent threshold levels for inventory rationing. In case of differentiation based on service contracts, we show that in addition to rationing thresholds we also need contract extension thresholds by which the system decides whether to offer an extension to an expiring contract or not. By numerical experiments in both cases, we identify the value of incorporating such decisions in service parts end-of-life inventory management with customer differentiation. Moreover, we show that these decisions not only result in cost efficiency but also decrease the risk of part obsolescence drastically

Revenue Management and Demand Fulfillment: Matching Applications, Models, and Software

Recent years have seen great successes of revenue management, notably in the airline, hotel, and car rental business. Currently, an increasing number of industries, including manufacturers and retailers, are exploring ways to adopt similar concepts. Software companies are taking an active role in promoting the broadening range of applications. Also technological advances, including smart shelves and radio frequency identification (RFID), are removing many of the barriers to extended revenue management. The rapid developments in Supply Chain Planning and Revenue Management software solutions, scientific models, and industry applications have created a complex picture, which appears not yet to be well understood. It is not evident which scientific models fit which industry applications and which aspects are still missing. The relation between available software solutions and applications as well as scientific models appears equally unclear. The goal of this paper is to help overcome this confusion. To this end, we structure and review three dimensions, namely applications, models, and software. Subsequently, we relate these dimensions to each other and highlight commonalities and discrepancies. This comparison also provides a basis for identifying future research needs.Manufacturing;Revenue Management;Software;Advanced Planning Systems;Demand Fulfillment