Showing papers on "Service level published in 1996"

Optimal EOQ Models for Deteriorating Items with Time-Varying Demand

Abstract: In this paper, optimal inventory lot-sizing models are developed for deteriorating items with general continuous time-varying demand over a finite planning horizon and under three replenishment policies The deterioration rate is assumed to be a constant fraction of the on-hand inventory Shortages are permitted and are completely backordered The proposed solution procedures are shown to generate global minimum replenishment schedules for both general increasing and decreasing demand patterns An extensive empirical comparison using randomly generated linear and exponential demands revealed that the replenishment policy which starts with shortages in every cycle is the least cost policy and the replenishment policy which prohibits shortages in the last cycle exhibited the best service level effectiveness An optimal procedure for the same problem with trended inventory subject to a single constraint on the minimum service level (maximum fraction of time the inventory system is out of stock during the planning horizon) is also proposed in this paper

Forecasting and Inventory Management of Short Life-Cycle Products

Abstract: In this paper, we provide an integrated framework for forecasting and inventory management of short life-cycle products. The literature on forecasting and inventory management does not adequately address issues relating to short life-cycle products. We first propose a growth model that can be used to obtain accurate monthly forecasts for the entire life cycle of the product. The model avoids limiting data requirements of traditional methods. Instead, it extracts relevant information from past product histories and utilizes the information on total life-cycle sales and the peak sales timing. Using disguised demand data from a personal computer PC manufacturer, we validate the model. 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 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 PC 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.

System and method for controlling the number of units of parts in an inventory

Abstract: A computer system according to the present invention comprises in a preferred embodiment a memory, a processor, an input and an output. The computer system receives part data and forecast data for each part in an inventory, including the number of units in the inventory, the cost, and the forecast unit demand. The computer system uses the part data and forecast data for each part to optimize the number of units of each part in the inventory for a selected inventory investment or service level constraint. The computer system optimizes the number of units of each part in the inventory by determining the number of units for each part for which the marginal increase in the number of orders for the part filled from the inventory for each additional order stocked is equal to the marginal increase for every other part and for which either the inventory service level equals the service level constraint or the inventory investment equals the inventory investment constraint. The computer system then outputs a determined minimum unit replenishment quantity and a safety unit quantity for each part. The minimum unit replenishment quantities and the safety unit quantity are used to determine the number of units of each part used to resupply the inventory.

Reducing Inventory Costs by Order Splitting in the Sole Sourcing Environment

Abstract: In this paper, we examine the possibility of the arrangement for multiple deliveries in each order cycle for the continuous review inventory system. The problem is mainly found in the retail sector where inventory often makes up the majority of a company's assets. Most works recently have focused on the reduction of safety stock in the multiple sourcing setting. This research, instead, considers the reduction of cycle stock in the sole sourcing environment. The formulation where a predetermined service level serves as a constraint for the objective function is employed throughout this research. We show that splitting the order into multiple deliveries can significantly reduce the inventory carrying cost especially when the interarrival times between deliveries are determined optimally.

Rare-Event Simulation for Multistage Production-Inventory Systems

Abstract: We consider the problem of precise estimation of service-level measures in multistage production-inventory systems when the system is managed for high levels of service. Precisely because the service level is high, stockouts, large backorders, and unfilled demands are rare and thus difficult to estimate by straightforward simulation. We propose and analyze alternative estimators, based on changing the demand distribution to make these rare events less rare. Whereas straightforward simulation for a fixed relative error results in computational requirements that grow exponentially in certain stock-level parameters, the requirements for our importance sampling estimators remain bounded for all parameter values. We provide bounds making it possible to determine the maximum number of replications required before any are generated. Numerical examples illustrate the effectiveness of our method.

The Art of Software Support: Design and Operation of Support Centers and Help Desks

Abstract: 1. Introduction. 2. Call Management Models. Achieving Customer Satisfaction. Call Flow Models. Other Call Management Considerations. Escalations. 3. Call Management Implementation. Hotline Support Basics. Phone Interface. Call Routing. Escalation Management. Non-phone Based Support. Disaster Recovery Planning. 4. Measuring Support Center Performance. Important Process Metrics. Customer Satisfaction. Analysis Metrics. 5. Packaging Support Programs. What is a support package and why create one? Defining Successful Support Packages. Pricing and Selling Support Packages. Sample Support Offerings. 6. Support Organization Structure. Do I need an organization dedicated to Support? Third-Party Support: Outsourcing. Reporting Structure. Do I need more than one Center? Internal Structure of the Support Group. 7. Managing Support People. Planning Support Staffing Needs. Hiring Support Staff. Managing Support Staff Performance. Retaining Support Staff. Managing Morale. 8. Managing Software Bugs and Code Fixes. Definitions and Models for Bug Fixing. Bug Fixing Process. Fixes for Third-Party Products. 9. Tools for Software-Support. Choosing, Justifying, and Implementing Tools. Phone System. Fax System. Call Tracking System. Bug Tracking System. Knowledge Base System. Proactive Customer Communication Systems. Customer Tracking System. Problem Reproduction Environment. Call Center Management Applications. Facilities. 10. New Product Planning. Planning for New Products. Training for New Products. Testing for New Products. Appendix A. Sample User's Guide. Appendix B. Call Resolution Overview. Framing the Call. Problem Solving. Creative Brainstorming. Checking Satisfaction. Appendix C. Determining Staffing Levels. Deriving a Staffing Level Knowing the Service Target. Deriving a Service Level from the Staffing Level. Effect of Call Length on Service Level. Theoretical Proof of "Big is beautiful". Appendix D. Creating and Justifying a Support Center Budget. Justifying a Support Center Budget. Building a Support Center Budget. Bibliography. Index.

A corporate operation framework for network service management

Abstract: The trend toward client/server computing and the growing complexity of management tasks requires a service-oriented definition of the business processes involved in managing distributed systems and networks Service-oriented management calls for an integrated top-down approach, that is, evaluating the services offered and the networks and systems used in order to select and customize management systems The corporate operation framework (COF) is presented This framework provides a general description and structuring format for IT management processes based on the service providers' point of view A brief summary of the TMN-related management levels that can be described by using the COF is outlined At the service level, services and their QoS are specified How these services are realized is defined at the task level, where each service is assumed to be provided by the workforce through fulfilling certain tasks The process level describes programs of actions (ie, processes to be followed when working on a task) Each action within a process is mapped to specific tools that are described at the tool level The COF clearly separates different description levels and provides well-defined interfaces between these levels This precise description is a prerequisite for the flexibility and durability of the framework, for example, when replacing tools, changing processes or introducing in- and outsourcing to the organization

Local Government Structure and Urban Residential Location

Abstract: The large research literature on the Tiebout model has developed with little attention paid to the urban economic structure in which local government functions. This paper attempts to examine the theoretical consequences of local jurisdictions functioning within a conventional monocentric urban model. It also discusses a mathematical formulation of a two-jurisdiction linear city in which the local service level and local property tax rate might be used as strategic variables in a game theory sense. It is concluded that for this to happen, the local service level has to have more than one element, which is intuitively appealing. Some references are developed to current British local government and possible changes.

Performance Evaluation Models for Single-item Periodic Pull Production Systems

Abstract: A number of pull production systems reported in the literature are found to be equivalent to a tandemqueue so that existing accurate tandem-queue approximation methods can be used to evaluate such systems. In this study, we consider developing an exact performance evaluation model for a non-tandemqueue equivalent pull production system using discrete-time Markov processes. It is a periodically controlled serial production system in which a single-item is processed at each stage with an exponential processing time in order to satisfy the Poisson finished product demand. The selected performance measures are throughput, inventory levels, machine utilizations and service level of the system. For large systems, which are difficult to evaluate exactly because of large state-spaces involved, we also propose a computationally feasible approximate decomposition technique together with some numerical experimentations.

How many units will be short when stockout occurs

Abstract: In stochastic inventory management, when calculating the safety stock necessary to ensure a service level, use of the partial expectation function, which is tabulated in the normal demand case, is popular. Using these values, it is possible to calculate the safety stock necessary for the average of the items not served by cycle to reach the desired level. Analyses the use of a conditional probability distribution to ascertain the safety stock necessary to guarantee, when stockout occurs, that the average of the number of items not available equals a predefined value.

Barriers to complaints: a survey of mental health service users

Abstract: Reports on a survey of 222 mental health service users in two health service trusts, which provides evidence to support and elaborate Wood’s analysis of barriers to effective complaints procedures. Identifies key confounding factors such as: lack of awareness of the existence of procedures, the fears of service users about making a complaint, and the lack of awareness of rights and expectations of services. Notes key implications for managers including: the provision of accurate, comprehensive information to service users about complaints procedures, the need to recognize the many factors which inhibit service users from using procedures and the need to inform service users about their rights and services.

Optimal EOQ Models for Deteriorating Items with

Abstract: In this paper, optimal inventory lot-sizing models are developed for deteriorating items with general continuous time-varying demand over a finite planning horizon and under three replenishment policies. The deterioration rate is assumed to be a constant fraction of the on-hand inventory. Shortages are permitted and are completely backordered. The proposed solution procedures are shown to generate global minimum replenishment schedules for both general increasing and decreasing demand patterns. An extensive empirical comparison using randomly generated linear and exponential demands revealed that the replenishment policy which starts with shortages in every cycle is the least cost policy and the replenishment policy which prohibits shortages in the last cycle exhibited the best service level effectiveness. An optimal procedure for the same problem with trended inventory subject to a single constraint on the minimum service level (maximum fraction of time the inventory system is out of stock during the planning horizon) is also proposed in this paper.

Managing a broadband environment: "you can't buck the market"

Abstract: Demand for bandwidth seems unstoppable, and investment in network infrastructure is massive. There is a desire that network operators be able to manage these networks in an efficient manner, with flexibility to support new customer service opportunities faster and cheaper. Network operators are looking to standards to help them meet this challenge. The telecommunications management network (TMN) model, so effective in describing how management information must support needs at the element, network, and service levels, provides a good starting point. However, if the supporting standards are not developed and used wisely, a TMN approach can have the opposite effect of adding cost and removing flexibility. Technology-specific "stovepipes" may make it impossible to manage services across a range of technologies. The authors express their views on the need for a service-driven approach to standards implementation. They point out specific challenges operators will face as they approach their management systems' needs for broadband services, and encourage service providers and network operators to take a more proactive role in defining their needs.

Better public transport: passengers' valuation of time and service improvements

Abstract: Stated Preference studies return important information about the passengers relative priority of different kinds of improvements. The studies give indicators of how the users value alternatives for investments in the system. Similar Stated Preference studies have been conducted in six different cities in Norway. This study is based on computerised home interviews of regular public transport passengers. During the interview each person was given the opportunity to choose among alternative packages of service levels. Each package described a public transport service of different standard for certain factors and various costs connected to this service level. The preferred choices of the interviews made it possible to estimate the individual valuations of the different service factors. The following factors were specified: reduced travel time (including walking, waiting and interchange time), improved regularity, improved quality on the stops and vehicle standard. The study also contains different questions connected to the competition between public transport and car, bicycle and walking. The results show that the value of time varies with different levels of service and market segments. For the covering abstract, see IRRD 890269.

System and method for controlling number of units of parts in invetory

Abstract: A computer system according to the present invention comprises in a preferred embodiment a memory, a processor, an input and an output. The computer system receives part data and forecast data for each part in an inventory, including the number of units in the inventory, the cost, and the forecast unit demand. The computer system uses the part data and forecast data for each part to optimize the number of units of each part in the inventory for a selected inventory investment or service level constraint. The computer system optimizes the number of units of each part in the inventory by determining the number of units for each part for which the marginal increase in the number of orders for the part filled from the inventory for each additional order stocked is equal to the marginal increase for every other part and for which either the inventory service level equals the service level constraint or the inventory investment equals the inventory investment constraint. The computer system then outputs a determined minimum unit replenishment quantity and a safety unit quantity for each part. The minimum unit replenishment quantities and the safety unit quantity are used to determine the number of units of each part used to resupply the inventory.

Of calls and callers

Abstract: The transition from post to telephone as the principle interface of a customer service department has permitted substantial cost savings. In general the written interface is slower than the real time interface and consumes more internal resource. On the other hand the real time interface complicates the management and planning process. This article shows how historical information may be used to crew a customer service department to optimum resource conditions, minimising costs and maximising service levels.

An integrated materials handling model for machine location in existing facilities

Abstract: A machine location criterion is proposed for situations where machines must be located in existing facilities to manufacture new products The location criterion is based on a measure of materials handling service It is applicable when an existing, automated materials handling system is fully integrated within an existing manufacturing facility The service level is measured by the expected rate of unsuccessful load transfers associated with a fixed production schedule, handling system, and assignment of machines to locations in a facility An analytical model focused on the interfaces of automated materials handling systems is formulated to predict the corresponding service level associated with alternative machine locations in an existing facility The model is illustrated through a sample problem which demonstrates how the specific operating characteristics of a typical automated materials handling system can be modelled to predict handling performance for alternative machine locations

Scheduling stocks and storage space in a volatile market

Abstract: Examines three areas within warehouse management of stocks: determining material requirements; establishing storage needs; and controlling supplies. Based on an example of a company manufacturing different boxed games, Monopoly for example, argues for slick scheduling to bring stock under control and enhance the service level to the production line.

Designing system availability into the service quality of automated facilities

Abstract: Investigates how system availability can be designed into the service quality of automated facilities With the advent of new and advanced technologies and the growing dynamics of global competition, many service facilities are resorting to automation as a means of not only providing prompt service, but also improving quality and productivity To achieve these goals, the system must be reliable and available to provide the needed services Describes and models a processing facility to show how quality and productivity can be improved when system availability is maximized Uses simulation to build the model Develops and applies a regression metamodel within a cost structure to determine the optimal number of standby processors and maintenance staff required to achieve a target service level

Service level agreements

Abstract: In the United Kingdom there is now a Charter for Higher Education which lays certain duties on universities. One of these is to inform students, potential employers, and the local community of the services and facilities available to them. This does not constitute a requirement of Service Level Agreements but a number of university libraries and other academic services have started to produce their own charters, service agreements and similar documents, and there is a great deal of interest in this topic

Distributed Computing Environment Monitoring and User Expectations

Abstract: This paper discusses the growing needs for distributed system monitoring and compares it to current practices. It then goes on to identify the components of distributed system monitoring and shows how they are implemented and successfully used at one site today to address the Local Area Network (LAN), network services and applications, the Wide Area Network (WAN), and host monitoring. It shows how this monitoring can be used to develop realistic service level expectations and also identifies the costs. Finally, the paper briefly discusses the future challenges in network monitoring.

Privacy and Authenticity in PONs

Abstract: In this section the privacy and authenticity problems of an ATM PON with tree topology are studied. In conventional networking a frequently taken view is: privacy is a problem of the applications and should be solved by them. This approach is not applicable to the PON situation: PONs should become parts of the B-ISDN and as such they should be indistinguishable from other parts of the network from both an user’s and an operator’s point of view. The required homogeneous and ubiquitous service level can only be achieved by a service enhancement for the PON to meet the accepted standard of privacy and authenticity found with star-shaped networks. The situation is very much akin to the service level enhancement introduced by a CRC check in order to reduce the residual bit error rate on a link or a LAN. The measures have to be taken in the physical layer rather than in the application layer and therefore in our context the appropriate measures have to cope with data rates above 600 Mbit/s.

Architectural design and implementation of the Singapore high-speed ATM-testbed

Abstract: This paper covers some technical planning and design issues of the Singapore national ATM network testbed. The network architecture and current implementation are discussed. We elaborate on a reference model that is aimed at effectively addressing the challenge of supporting multiple multimedia services over a broadband network with quality of service (QOS) guarantees and exhibits scalability and manageability properties. The model separates user information transport from control, and management. It applies QOS abstractions to simplify resource allocation for multimedia connections, and suggests a service abstraction for supporting service level control and management. Finally, the current implementation status of the testbed is presented.

A New Approach to Contract Specification

Abstract: The task of producing and reviewing contracts — or service level agreements (SLAs) — requires a detailed knowledge of the business processes, business drivers (e.g. costs, efficiency) and co-operating business units. In a large organization it is impossible for a small number of individuals to carry out this task, so responsibility for SLA specification is generally distributed. Differences in approach to the task can result in inconsistencies in the way measures are used within similar SLAs. One consequence of this is that a large number of unnecessary performance measures may be created. Mechanisms for monitoring, storing, processing and maintaining each of these additional measures have to be implemented and maintained, and large amounts of extra data therefore have to be handled. Additionally, changes to the process, the organizational units and particularly the business drivers can impact on the measures chosen for a specific SLA. There is, therefore, a need to: minimize the time and effort required to produce SLAs; create and use measures consistently; minimize the measures required for each SLA; maximize the flexibility of SLAs with respect to the business drivers.