Showing papers on "Service level published in 1981"

Effect of service-levels on order-points or order-levels in inventory models

Abstract: Obtaining the desired service-level is one of the most important problems in inventory control. The term ‘service-level’ has been interpreted in several ways. This paper presents a survey of the three most common service measures and the mathematical calculations pertaining to each.

A stochastic service network model with application to hospital facilities.

Abstract: This paper presents a methodology for estimating expected utilization and service level for a class of capacity constrained service network facilities operating in a stochastic environment. A semi-Markov process describes the flows of customers (patients) through a network of service units. We model the case where one of the units has finite capacity and no queues are allowed to form. We show that the expected level of utilization and service can be computed from a simple linear relationship based on (a) the equilibrium arrival rates at each unit which are associated with the case of infinite capacity, (b) mean holding times for each unit, and (c) the probability that the finite capacity unit is at full capacity. We use Erlang's loss formula to calculate the probability of full capacity, show this calculation to be exact for two cases, and recommend its use as an approximation in the general case. We test the accuracy of the approximation on a set of published data. In the discussion, we present a techniq...

Physical Distribution: The Analysis of Inventory and Location

Abstract: The cost and service level performance of a manufacturing system or a distribution system depend heavily on the interaction between the physical system design and the inventory control system. This paper examines that interaction and provides some general analytical guidelines for (1) the determination of total system inventory and its distribution within a fixed system design, and (2) the determination of system design as suggested or favored by inventory considerations.

Service Level Relationships in a Multi-Echelon Inventory System

Abstract: This paper deals with a multi-echelon inventory system consisting of one central Distribution Center DC which is the source of supply for any number of Regional Distribution Centers RDC's which are the source of supply for customer demand. It develops and tests through the use of simulation a heuristic for determining what level of service the customer receives given any combination of DC and RDC service levels, where service is defined as the fraction of demand met from on-hand inventory at the location where the order is placed. A number of different combinations of DC and RDC service level will achieve any given level of customer service. The criterion used to identify the best combination is the minimization of the average level of total system inventory.

Inventory Control Using A Service Constraint on the Expected Duration of Stockouts

Abstract: This paper addresses the selection of a reorder point under a management-specified, maximum expected duration of stockout during a replenishment lead time. The cases of normal and Poisson demand are considered. In both cases graphical aids are developed, allowing easy determination of the reorder point so as to achieve a desired service level. The entire probability distribution of the durations of stockouts is also developed in each case.

Multi-Item Inventory Management with Monetary Objective Function

Abstract: This paper summarizes an actual multi-item periodic-review inventory control study where the “order-up-to-S” policy is employed. The objective function is expressed in monetary terms and is optimized subject to a budgetary limit on the maximum amount of money that can be tied up in inventories. The optimal solution is obtained by employing the generalized Lagrange multipliers method. Findings indicate that it is possible to decrease by at least 37.5% the amount of money currently invested in inventories while maintaining an 85-90% service level to customers. In this study a considerable amount of effort is also spent on the estimation of cost parameters, especially the shortage cost.

Preliminary design and evaluation of coordinated public transportation services

Abstract: An integrated system of coordinated transit services described is shown to offer potential improvements in the productivity and efficiency of transit operations in low density urban areas. The recommended method allows for a formal evaluation of feasible alternatives relative to the established system objectives, and the results of the evaluation can be interpreted to show how systems that provide minimal service levels can be implemented to evolve into a system with higher levels of service. Scheduling and transfer considerations are developed in a subsequent detailed design phase of the planning process.

Scaling methods: measurement of the service level of centers in noord‐brabant (the netherlands)

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On Mobile Service Units: Some Mathematical Considerations

Abstract: The paper develops several relationships that can help determine operational characteristics of a mobile service unit. Specifically, it presents a heuristic for the determination of a service area using service level and waiting time criteria and deals with the dectralization of service units. These relationships may be applied in various contexts: assignment of maintenance crews, dispatching material handling equipment, determinmg airlines service areas, among others.