Analytical approximations to predict performance measures of manufacturing systems with job failures and parallel processing

Parallel processing is prevalent in many manufacturing and service systems. Many manufactured products are built and assembled from several components fabricated in parallel lines. An example of this manufacturing system configuration is observed at a manufacturing facility equipped to assemble and test web servers. Characteristics of a typical web server assembly line are: multiple products, job circulation, and paralleling processing. The primary objective of this research was to develop analytical approximations to predict performance measures of manufacturing systems with job failures and parallel processing. The analytical formulations extend previous queueing models used in assembly manufacturing systems in that they can handle serial and different configurations of paralleling processing with multiple product classes, and job circulation due to random part failures. In addition, appropriate correction terms via regression analysis were added to the approximations in order to minimize the gap in the error between the analytical approximation and the simulation models. Markovian and general type manufacturing systems, with multiple product classes, job circulation due to failures, and fork and join systems to model parallel processing were studied. In the Markovian and general case, the approximations without correction terms performed quite well for one and two product problem instances. However, it was observed that the flow time error increased as the number of products and net traffic intensity increased. Therefore, correction terms for single and fork-join stations were developed via regression analysis to deal with more than two products. The numerical comparisons showed that the approximations perform remarkably well when the corrections factors were used in the approximations. In general, the average flow time error was reduced from 38.19% to 5.59% in the Markovian case, and from 26.39% to 7.23% in the general case. All the equations stated in the analytical formulations were implemented as a set of Matlab scripts. By using this set, operations managers of web server assembly lines, manufacturing or other service systems with similar characteristics can estimate different system performance measures, and make judicious decisions - especially setting delivery due dates, capacity planning, and bottleneck mitigation, among others.

Analytical Approximations to Predict Performance Measures of Manufacturing Systems with Job Failures and Parallel Processing

Parallel processing is prevalent in many manufacturing and service systems. Many manufactured products are built and assembled from several components fabricated in parallel lines. An example of this manufacturing system configuration is observed at a manufacturing facility equipped to assemble and test web servers. Characteristics of a typical web server assembly line are: multiple products, job circulation, and paralleling processing. The primary objective of this research was to develop analytical approximations to predict performance measures of manufacturing systems with job failures and parallel processing. The analytical formulations extend previous queueing models used in assembly manufacturing systems in that they can handle serial and different configurations of paralleling processing with multiple product classes, and job circulation due to random part failures. In addition, appropriate correction terms via regression analysis were added to the approximations in order to minimize the gap in the error between the analytical approximation and the simulation models. Markovian and general type manufacturing systems, with multiple product classes, job circulation due to failures, and fork and join systems to model parallel processing were studied. In the Markovian and general case, the approximations without correction terms performed quite well for one and two product problem instances. However, it was observed that the flow time error increased as the number of products and net traffic intensity increased. Therefore, correction terms for single and fork-join stations were developed via regression analysis to deal with more than two products. The numerical comparisons showed that the approximations perform remarkably well when the corrections factors were used in the approximations. In general, the average flow time error was reduced from 38.19% to 5.59% in the Markovian case, and from 26.39% to 7.23% in the general case. All the equations stated in the analytical formulations were implemented as a set of Matlab scripts. By using this set, operations managers of web server assembly lines, manufacturing or other service systems with similar characteristics can estimate different system performance measures, and make judicious decisions - especially setting delivery due dates, capacity planning, and bottleneck mitigation, among others.

Comparative Administrative Reform: The Rhetoric and Reality of the Civil Service Reform Programs in Uganda and Tanzania

Administrative reform is a challenging endeavor for both developed and developing countries alike. For developing countries, the challenge is greater because numerous reforms are implemented concurrently sometimes under conditions of resource scarcity and political instability. So far there is no consensus as to what makes some reforms succeed and others fail. The current study seeks to fill that gap by offering an empirical comparative analysis of the administrative reforms initiated in Uganda and Tanzania since the early 1990s. The purpose of the study is to explain the similarities and differences, and give reasons for the successes and failures of the reform programs in the two countries. It focuses on four major areas; the size of the civil service, pay reform, capacity building, and ethics and accountability. Data were collected via in-depth face to face interviews with 35 key government officials and the content analysis of various documents. The results indicate that the reforms generated initial substantial reduction in the size of the public services in both countries. In Uganda, the traditional civil service was reduced from 140,500 in 1990 to 41,730 in 2004; while in Tanzania Ministries, Departments, and Agencies were reduced by 25%. Pay reform has generated substantial increases in civil servants’ salaries in both countries but in Uganda, the government has not been able to abide by the pay strategy while in Tanzania the strategy guides the increments. Civil Service capacity building efforts have focused on enhancing the skills of the personnel. Training needs assessments were undertaken in all ministries in Uganda and a training policy was formulated. In Tanzania, the training needs assessments are still under way and a training policy has not yet been developed. Ethics and accountability are great challenges in both countries, but in Tanzania, there is more political will and commitment to improve the integrity of the civil service. The findings reveal that although Uganda started the reform with much more rigor and initial success, Tanzania has surpassed it and has a more stable, consistent, and promising reform record. This is because Uganda’s leadership lacks political legitimacy. The country has since the late 1990s experienced a civil war in the northern and western parts of the country while Tanzania has benefitted from relative peace and high level political legitimacy.

Shining Examples of Service When the Lights Went Out: Hotel Employees and Service Recovery during the Blackout of 2003

The electrical outage in the summer of 2003 that interrupted power to thousands of hotels wrought a variety of facilities failures and service-process problems. Fortunately, strong service-recovery efforts from hotel employees mitigated the worst of the blackout’s effects. Using survey data from hotel managers who experienced the blackout, this study highlights those employee actions that most contributed to immediate service recovery; however, the study also reveals limited organizational learning or efforts to failsafe hospitality service from the eventuality of future power failures.

Having a strategy for new service development : does it really matter?

Purpose – The aim of this study is to investigate the role of key strategic factors in new service development (NSD). In particular, the role of service development strategy, a formalised development process, integrated development teams and customer co-creation were investigated and the results were compared with managers' beliefs. Design/methodology/approach – The study used a sample of more than 500 service development projects to test a NSD conceptual model. Regression analysis was used to test the relative importance of the key strategic factors, and the results were compared with managers' beliefs. Findings – The results show that managers believe that customer co-creation is most important in order to succeed with NSD. However, contrary to management belief, a service development strategy is the “missing link” in improving NSD performance. In addition, the research highlighted an interaction effect between integrated development teams and customer co-creation, which means that project managers should focus on individual competencies on the development team and how they interact with customers throughout the NSD process. Originality/value – For a long time, NSD has failed to receive the attention it deserves, not just in practice but also in service research. This study shows that the number of new services put on the market and then withdrawn because of low sales remains as high as 43 per cent. This paper contributes knowledge on how to reduce the number of failures in NSD by pointing out the key strategic factors that influence NSD performance.

Using Needs Assessment to Understand Continuing Disability in Patients with Enduring Mental Illness. Implications for Considerations of Service Development

Particular strengths of the MRC Needs for Care Assessment Schedule have been used to investigate the treatment status of patients with persistent psychiatric disability in ways that other needs assessment tools are unable to. One hundred and seventy-nine such patients from three settings; a private sector psychiatric hospital, two public sector day hospitals situated in the same town, and a high security hospital, were found to have a high level of need. Although there were differences between settings, overall these needs were well met in all three. The high level of persistent disability found amongst these patients could not be attributed to failure on the part of those treating them to use the best available methods, or to failures to comply or engage with treatment on the patient's part. In some two thirds of instances persistent disability was best explained by the fact that even the most suitable available treatments have to be considered only partially effective.

Queueuing system with failures and priorities

Queueing theory provides models, structural insights, problem solutions and algorithms to many application areas. Due to its practical applicability to production, manufacturing, home automation, communications technology, etc, more and more complex systems requires more elaborated models, tech- niques, algorithm, etc. need to be developed. Discrete-time models are very suitable in many situations and a feature that makes the analysis of discrete time systems technically more involved than its continuous time counterparts. In this paper we consider a discrete-time queueing system were failures in the server can occur as-well as priority messages. The possibility of failures of the server with general life time distribution is considered. We carry out an extensive study of the system by computing generating functions for the steady-state distribution of the number of messages in the queue and in the system. We also obtain generating functions for the stationary distribution of the busy period and sojourn times of a message in the server and in the system. Performance measures of the system are also provided.

Structuring the Inside of a New-born Business – Case of a Consulting Service Company

When starting a new business, most entrepreneurs usually focus on the external aspects in order to make their new business successful. Consequently, most research in entrepreneurship has been focused on the external factors to explain the high rate of entrepreneurial failures. But there is also a lack of consideration of the internal aspects by the new entrepreneurs. This paper focuses on these internal aspects and how to help a new business implementing an internal strategy.

Toward Self-Organising Service Communities

This paper discusses a framework in which catalog service communities are built, linked for interaction, and constantly monitored and adapted over time. A catalog service community (represented as a peer node in a peer-to-peer network) in our system can be viewed as domain specific data integration mediators representing the domain knowledge and the registry information. The query routing among communities is performed to identify a set of data sources that are relevant to answering a given query. The system monitors the interactions between the communities to discover patterns that may lead to restructuring of the network (e.g., irrelevant peers removed, new relationships created, etc.).