Showing papers on "Service level published in 1992"

An integrated approach to forecasting and inventory management of short life cycle products

Abstract: This research is an attempt to provide an integrated framework for forecasting and inventory management of short life cycle products. Short product life cycles are becoming increasingly common in several consumer and industrial goods industries. Management of the marketing and production functions for these products presents significantly different challenges than those for longer lasting products. The timing of decisions and the information available for decision making are both affected by the shortened life cycles. The literature on forecasting and inventory management does not adequately address issues relating to short life cycle products. In the first part of this research we develop growth models that can be used to obtain accurate monthly forecasts for the entire life cycle of the product. The models avoid the limiting data requirements of traditional methods. Instead, they extract relevant information from past product histories and use the information on total life cycle sales and the peak sales timing. Empirical testing, on disguised real life data from a PC Manufacturer, validates these models. Model fit and forecast comparisons with traditional approaches show that the proposed models outperform these approaches. Next, we model the inventory management problem for the short life cycle environment. The uncertainty in demand is modeled through the uncertainty in the realized values of the parameters of the forecasting model. The high cost of terminal inventory, shortages and rapidly changing procurement costs are all included in the model. Extensions to the basic model are also developed. Using optimal control theory, we derive a solution that provides valuable information on procurement cutoff time and terminal service levels. A detailed real life example explains the characteristics of the policy and its relevance in decision making. Many of the issues covered in the models were brought to our attention while implementing a forecasting model at a Personal Computer manufacturer. The benchmark monthly forecasts and the associated inventory levels provide information that can be very helpful in planning and controlling marketing, sales and production. By raising some issues this research also provides useful topics for further research in the area of management of short life cycle products.

Production batching with machine breakdowns and safety stocks

Abstract: We study the problem of selecting the economic lot size for an unreliable manufacturing facility with a constant failure rate and general randomly distributed repair times. Safety stocks must be used to meet the managerially prescribed service level (the fraction of lost sales) because these stochastic interventions reduce the effective production capacity. We develop bounds on the range of feasible service levels and investigate the impact of several system parameters on this range. We introduce an easily implementable production control policy (but do not establish the optimality of its structure) and prove that under this policy the safety stock dynamics can be characterized fully by a renewal process analogous to the workload process of a special single server queueing system. This analogy is exploited in deriving exact and approximate expressions for the safety stock holding costs. Several operational insights are revealed by experimenting with the models developed here. We show how the results can b...

Service Level in Multistage MRP and Base Stock Controlled Production Systems

Abstract: A manufacturing system consisting of a number of stages in series is considered. Each stage has limited capacity and the processing times at the stages are random so queueing of work in process can occur at any stage. External demands should be met from final product inventory, but because of queueing effects not all demands can be met immediately. The service level provided by the system will be influenced by the approach used to initiate work release to each stage (such as MRP or base stock coordination) and by management set parameters such as the stage lead times, safety stocks and echelon target stocks. Based on a sample path analysis an approach for finding performance bounds is developed. An approximation scheme is tested by comparison with simulation on a number of two stage systems. Finally, some interesting conclusions about the design of MRP and base stock systems are drawn.

Demand Management and Production Control in Process Industries

Abstract: In a changing and more dynamic market of the 1980s, available mathematical programming algorithms on which production planning in process industries was based did not provide the required responsiveness. Although it is suggested in the literature that a variable cycle times policy will enable the system to react to short‐term demand fluctuations, proposes the use of a fixed cycle times policy. Presents simulation results which show a considerable improvement in service level at a high level of utilization. Presents a three‐tiered hierarchical model which is based on this fixed cycle times policy, which gives insight into the influence that the demand manager has upon the results in the production department. On the other hand, it also reflects the commercial interests. Suggests that for both departments which are this strongly intertwined, a common reference is necessary to improve the general results of the business.

Effect of increasing component commonality on service level and holding cost

Abstract: We investigate the effect of increasing component commonality in an assemble-to-order system. Numerical investigation of two end products that share up to three components, and whose demands are identically distributed according to either the exponential or the geometric distribution, shows that increasing component commonality results in increasing marginal returns when the criteria are aggregate service level and aggregate stock requirement. For arbitrary end-product demands and general service measures, it is shown that the optimal holding cost for a given service level is concave in the level of commonality. © 1992 John Wiley & Sons, Inc.

Customer waiting times in an (R,S) inventory system with compound poisson demand

Abstract: Besides service level and mean physical stock, customer waiting time is an important performance characteristic for an inventory system. In this paper we discuss the calculation of this waiting time in case a periodic review control policy with order-up-to-levelS is used and customers arrive according to a Poisson process. For the case of Gamma distributed demand per customer, we obtain (approximate) expressions for the waiting time characteristics. The approach clearly differs from the traditional approaches. It can also be used to obtain other performance characteristics such as the mean physical stock and the service level

Method for more efficient service request processing

Abstract: A communication resource allocator of a trunking communication system may more efficiently handle service requests during extremely busy times in the following manner. While receiving service requests from communication units, the communication resource allocator determines whether it can process the service request within a predetermined period of time. If the communication resource allocator cannot process the service request within a predetermined period it generates a global system busy which indicates that the communication resource allocator cannot individually process or acknowledge additional service requests. Having generated the global system busy signal, the communication resource allocator transmits it to the plurality of communication units. The communication units process the global system busy signal such that they will not transmit nonpriority service requests during the duration of the global system busy signal. While the global system busy signal is active, the communication resource allocator processes received service requests and any service request having a priority service level until the processing time of the non priority service request is at least a portion of the predetermined period of time.

Effects of Inventory Miscount and Non-Inclusion of Lead Time Variability on Inventory System Performance

Abstract: This paper addresses concerns of die management of a service parts organization for the realized service level [Pcirc], measuring parts availability (from shelf), being much lower than die prescribed service level P. The diagnostic study suggested the potential causes were die inventory miscount and die non-inclusion of lead time variability in computing reorder points. Quantitative measures for the degradation in the service level are derived as a function of the level of inventory miscount and the lead time variability. The prevailing levels of inventory miscount errors and lead time variability are estimated for a service parts organization with 45,000 parts and annual sales volume of $65 million. The composite degradation in service level P∘ is computed when these causes are operating individually and jointly. Handled by the Department of Inventory.

The global service quality measurement program at American Express Bank

Abstract: In 1991 American Express Bank launched a global service quality measurement program. Quantifying timeliness and accuracy of key banking services from a client perspective, the program has provided valuable input toward enhancing client service levels. Program automation and ongoing quality reporting are now helping the bank deliver consistent, superior service worldwide.

Effective Supplier Alliances and Partnerships

Abstract: What are supplier relationships? Looks at subjective and objective measures, how we set them up, how to choose partners, whom we should choose. The potential benefits are synergy, common goals, reduction of complexity, cost reduction and higher service levels.

Rail freight service productivity from the manager's perspective

Abstract: To be beneficial to management, productivity concepts must be translated into terms that are meaningful to managers at all levels of the organization. Productivity per se is not nearly as important to these people as service quality and financial performance, especially since measured productivity can improve while profits or service levels decline. Productivity must, therefore, be related to an integrated set of performance measures that reflect costs, revenues, trip times and reliability, equipment availability and other matters of continuing concern to transportation companies. Planning and control are critical components of any program to improve productivity. The techniques required to measure and understand productivity are precisely those used in planning and in developing control systems. Furthermore, productivity is conceptually very close to cost analysis, which is a major focus of planning and control. Any transportation company has access to the data needed to develop a vast array of performance measures, including many productivity measures. This paper will illustrate the way that railroads can integrate productivity concepts within more global performance measurement systems. Specific attention will be given to terminal control systems, costing systems for origin-to-destination movements and life-cycle costing techniques for track maintenance planning.

Stockout Costs in Distribution Systems for Spare Parts

Abstract: Details an empirical study of the measurement of stockout costs in a distribution system and examines the incidence of stockouts in the supply of spare parts to the motor trade. Comprehensive studies were conducted in three major car workshops in Sweden and cost data collected from a variety of sources, including structured observation, quasi‐experiments, interviews and secondary data from internal information systems. On the basis of this research, a typology of stockout cost situations has been constructed and central concepts and measurement models developed. Results reveal that stockout costs are measurable in the system under review; information about stockout costs can have a significant impact on managerial decision making.

Deterministic Inventory Models

Abstract: J.M. KEYNES differentiated three motives for holding money which can be applied to inventory problems.

A Dependability Measure for Degradable Computing Systems

Abstract: This paper deals with the problem of finding a comprehensive dependability measure or figure of merit for computing systems. Dependability is a term used for a general description of a systems trustworthiness in non-quantitative terms. It is commonly described by a number of aspects, like reliability, availability, safety and security. Quantitative measures are conveniently used for e.g. reliability and availability, but are rare for security. However, it is felt that a more general measure of a system’s dependability would be of great interest and could be used for system evaluations, design trade-offs etc. In order to achieve this, we adopt a generalized view that facilitates a recompilation of the dependability aspects into fewer and more general qualities. Key issues for the generalization are the concepts of degradability and service. A degraded service is the result of the discontinuation of one or several subservices, yielding a system that operates on a reduced service level. A vectorized measure based on Markov processes is suggested, and mathematical definitions are given. The measure describes the expected time a system will be operating at a certain service level, and also the probability that this level be reached. By means of applying the concept of reward rate to each service level, an even more simplified figure of merit can be calculated. Normally, when making reliability calculations, an assumption of exponential failure rates for system components is made. Sometimes this assumption is not realistic and we outline how phase-type distributions can be used to cope with this situation. Finally, two different schemes for the calculation of the measure is given. First, a hierarchical procedure feasible for small systems and calculations by hand is presented. Second, a general procedure based on matrix calculus is given. This procedure is suitable for complicated systems. It is also general in the sense that it may be used for measures extended to repairable systems.

Logistics Networks: Achieving Quantum Improvements in Cost/Service Equations

Abstract: Examines the paradox facing companies in general of how to take cost out of a logistics network, while simultaneously maintaining or improving agreed levels of service, and seeks an answer in the fields of behavioural science, culture, organizational design and operations research. Taking one UK company as an example, looks at aspects of quality service, product behaviour vis‐a‐vis logistics, optimization modelling, the various phases of the model and the expected benefits of the whole project. Concludes that organizations following this methodology have acquired the means to ascertain strategic and tactical shifts in direction without being compelled to make on‐the‐ground changes.

Business planning in local government

Abstract: Agreeing and clarifying objectives analysis of the past restraints determining means and actions by which targets are to be achieved determining the organization's position new areas of activity being analyzed and chosen solely to assist the Authority in meeting its declared objectives monitoring, reporting and revising service level agreements market strategy cash flow. Appendix: Examples of business plans and market strategies.

Formulating Strategy in the Pod

Abstract: Decision Conferencing is a methodology which aims to improve the efficiency and outcomes of meetings which are called to address strategic issues. This article describes one particular Decision Conference involving elected members and officers of Welwyn Hatfield District Council, at a point in time when fundamental changes were required concerning financial and service level strategies for a four-year period.

Online Public Access Catalogs: Remote Access and the Invisible User

Abstract: Looks at the needs to begin planning for remote access to online public access catalogs (OPACs), and to consider the special needs of the remote user – beginning at the institutional level – for example, how well does the campus network match up to the ideal service level of easy access for every faculty member and student? Considers other possibilities, such as dial access, dedicated workstations or local area networks. Makes the point that the existence of the service must be advertised, potential users of remote services are unlikely to be aware of its existence if it has not been advertised outside of the library itself. Document delivery is another important issue that needs to be addressed if the remote user is to receive satisfactory service levels.

Method and apparatus for detecting faulty software component

Abstract: PURPOSE: To detect a software modul where a fault occurs and to help the recovery of a system by requesting a service or a service level from one target and inspecting response within a prescribed time interval. CONSTITUTION: Probe mechanism 37 executes communication with usage possibility managing program 38 and a program 38 outputs a detected error to a recovery management program supporting function 39. Here, the probe 37 request a certain service from one target which is selected from a set consisting of the function group, the module group and the sub-system group of a running system. The target is regarded as the sound one when the service is executed by a good timing and is regarded as the fault unless the service is executed by the good timing. It is sound when the change of the service level is requested and the service level corresponding to the request is changed and the fault is labelled unless change corresponds to the request.

HIV/AIDS. Some organizational and managerial issues.

Abstract: Discusses factors emerging from research into the management and organizational processes involved in developing services for HIV/AIDS which affected the speed and character of the response made by health authorities. An early response was promoted by perceived high local prevalence, an existing service infrastructure, and high status individuals “championing” the issue and helping to foster a mobilizing sense of crisis. Responses were shaped by the diverse interests and perspectives of those developing services; the lack of established guidelines for treatment and service delivery, and ring‐fenced funding. The idiosyncratic nature of initial service development has sometimes made later strategic choices difficult. If the momentum of service development is to be sustained, HIV/AIDS needs to be integrated into mainstream service provision and managers need improved information about local prevalence and evaluation of service initiatives.

A fundamental identity in the lost sales inventory problem

Abstract: A FUNDAMENTAL IDENTITY IN THE LOST SALES INVENTORY PROBLEM A fundamental identity has been derived for the determination of the service level in a periodic review inventory model with a positive lead time and without backordering. The event of a stockout in the lead time, which is written as a union of events, in which each event represents a stockout during a specific period in the lead time, can be written as an intersection of events in which each event represents the total demand exceeding the scheduled receipts during (a part of) the lead time. A FUNDAMENTAL IDENTITY IN THE LOST SALES INVENTORY PROBLEM

Exploratory study on performance measures as indicators of IS effectiveness

Abstract: The Information Systems Directorate at JSC/NASA has undertaken the reevaluation of its performance measures process and measures. Under the direction of a quality approach it is essential to identify an external perspective of how well an organization is performing. This study was conducted with two major objectives: (1) survey and summarize the academic literature on performance measures as indicators of information systems (IS) effectiveness; and (2) survey organizations for their experience in measuring for IS effectiveness. Four approaches to measuring the effectiveness of IS performance were identified: (1) listen to the customer for the things they need; (2) align with corporate goals; (3) benchmark against well-respected organizations; and (4) ask yourself what critical factors lead to success. The list of known methods for soliciting customer feedback are as follows: (1) executive visit; (2) survey, interview, and focus group; (3) complaints and compliments; and (4) service level agreements. A common set of characteristics that satisfy customers was identified from the literature. The list includes elements such as the following: accuracy, timeliness, relevance, understandability, reliability, and completeness. Future research in this topic area should prove beneficial to determine the metrics for external validity.