41 research outputs found
Heuristics for batching and sequencing in batch processing machines
Get PDFIn this paper, we discuss the “batch processing” problem, where there are multiple jobs to be processed in flow shops. These jobs can however be formed into batches and the number of jobs in a batch is limited by the capacity of the processing machines to accommodate the jobs. The processing time required by a batch in a machine is determined by the greatest processing time of the jobs included in the batch. Thus, the batch processing problem is a mix of batching and sequencing – the jobs need to be grouped into distinct batches, the batches then need to be sequenced through the flow shop. We apply certain newly developed heuristics to the problem and present computational results. The contributions of this paper are deriving a lower bound, and the heuristics developed and tested in this paper
Dynamics of supply chain relationships: A qualitative study of logistics triads
No full textIn recent years, a growing number of organizations have outsourced logistics services to logistics services providers (LSPs). Consequently, the outcome of logistics outsourcing is significant in determining the outcome of contemporary supply chains. To account for greater interconnection between organizations, supply chain relationship is crucial for achieving successful logistics outsourcing. Because organizations need to continuously change their decision-making in outsourcing, relationships among organizations in outsourcing are dynamic. Further, because logistics outsourcing has created more SCRs among suppliers, LSPs, and customers, managers need to use a network perspective to manage multiple relationships in the process of outsourcing. The triadic relationship is recognized as the smallest network structure. Researchers have therefore suggested that studying triadic relationships can help expand the knowledge of managing network structures in supply chains. As a result, the primary goal of this research is to study dynamics of supply chain relationships in logistics outsourcing from a view of triadic relationship. This relationship is called a logistics triad and consists of a supplier, a logistics service provider (LSP), and their common customer.
Balance theory is a theory that was specifically developed for studying triadic relationships. Balance theory has been used in this thesis as a theoretical lens to develop a conceptual framework and research propositions in order to study logistics triads. Because only a few supply chain studies have adopted balance theory so far, there is a lack of a well-designed research instrument to investigate the research target that the present study explores. To rectify this paucity, qualitative research was conducted using multiple case studies to explore why and how a logistics triad transitions between different triadic relationship structures.
The present research was carried out in two stages. The first stage collected triadic cases from LSPs. To improve validity and reliability, the second stage used a deductive process to test findings of the first stage by collecting triadic cases from suppliers and customers. Results of the comparison between the two stages provided verified research findings because the two stages exhibited close similarity.
In stage one, the findings indicate that balance theory on its own is insufficient to explain the stability and dynamics of logistics triads. This led to the identification of factors that influenced the relationship dynamics in logistics triads. Among these factors, the combined effects of purchasing volumes, resource capability, and focal firm can override influences from other factors to determine stability and dynamics of logistics triads. The influence from the focal firm demonstrates that the supply network model is more useful than balance theory to study logistics triads.
Overall, this thesis makes four major contributions to the knowledge of supply chain relationships: developing an integrative model of triadic relationship dynamics, identifying control approaches used by organizations to dominate triads, comparison between balance theory and supply network model, and demonstrating organizations' mediating effects on dyadic relationships within triads
The measurement of internal supply chain integration
No full textPurpose: Internal supply chain refers to the chain of activities within a company that concludes with providing a product to the customer. This process involves multiple functions within companies such as sales, production, and distribution. It is obvious that a company's performance would be enhanced by the integration of these functions. However, there is no consensus yet on how integration is to be defined and measured. The purpose of this paper is to present research that was conducted with the goal of developing an instrument for the measurement of internal supply chain integration. Design/methodology/approach: Scale items were identified from current literature and the resulting survey instrument was sent out to a sample of New Zealand manufacturers. Statistical analysis was conducted to purify and validate the instrument. Findings: In total, three dimensions of integration were identified, labelled coordination, communication, and affective relationship. This paper makes a contribution towards developing a consensus in the understanding and measurement of the integration construct. Research limitations/implications: The selection and exclusion of measurement items for the survey have followed established principles of survey research, but may have been affected by the personal bias of the author. While every attempt has been made to comprehensively capture the state of the research up to the time of the study, there may be some omissions. The sample for the survey was drawn from a database of New Zealand businesses, thus the results are generalizable only to the extent that these businesses represent the population of all businesses. Another limitation is that no prior survey/case studies were carried out to collect practitioner's definitions/measures for integration. Practical implications: The authors hope to have made a contribution here towards building a consensus among practitioners and researchers in defining and measuring internal supply chain integration. For practitioners, the measurement instrument offers a self-assessment tool for internal supply chain integration. This should help them in identifying areas for improvement. Originality/value: The contribution of this paper consists of: development of an instrument for the measurement of integration, validating the instrument against a criterion, and the identification of three dimensions of integration - communication, coordination, and affective relationship. The unique contributions of this paper are the validation of the instrument against a criterion and the identification of "affective relationship" as a dimension of internal supply chain integration
Beyond certification: The maintenance of ISO 9000 in Malaysian service organisations
No full textThis research is an in-depth study of the quality management systems of two Malaysian "government-linked companies" (GLCs) classified as being in the service industry. Both are mature holders of ISO 9000 certification and the research focuses on how they have gone about maintaining and improving their quality management system (QMS), the extent to which they have succeeded, and what management and employees of the companies feel have been critical success factors and problems to be overcome. A case study approach is used for this study. The study has been comprehensive in its data collection with 30 individual face-to-face interviews with top management, middle management, lower management in charge of operations and quality, the management representative responsible for the implementation of ISO 9000 in the case companies being conducted, 300 questionnaires being distributed to employees of both companies, and a thorough review of ISO 9000 and other quality documents carried out. The results of the study showed that the two companies maintain their ISO 9000 based on the requirements of the standard. However, to support the technical requirements and in order to maintain the quality system more effectively and strive for excellence, the study highlights the need for integrating the human resource aspects of quality management into the quality system. Critical success factors of ISO 9000 maintenance identified are top management commitment, employee involvement, recognition and reward, teamwork, continuous improvement, and quality culture. The main problems associated with maintaining ISO 9000 faced by the companies are lack of cooperation and commitment from people, lack of knowledge and training, lack of communication, and lack of awareness and understanding on ISO 9000. Measures outlined to overcome the problems include closer interaction between people, training of management and employee on ISO 9000 and related subjects, skill and competency, and better communication. The study has identified lessons to be drawn by similar companies facing similar challenges and those striving for excellence. It has provided insights into the improvements and changes brought by the continued maintenance of the ISO 9000 after certification. It has also added to the knowledge on aspects of organisational development for service companies and casting new light on various theories put forward in the quality management literature. Further, the development of a framework for effective ISO 9000 maintenance in service organisations will enable it to be tested and compared with other industry frameworks in future studies
A hybrid genetic algorithm for a loading problem in flexible manufacturing systems
No full textOne of the operating decisions involved in the scheduling of flexible manufacturing systems (FMS) is that of loading the FMS. Given a pool of jobs, which can be processed on alternate machines and alternate tools, the scheduler has to decide on the allocation of tools and machines to the different jobs. Various versions of this problem have appeared in the literature. We consider the version where jobs are selected for processing in a FMS in a planning horizon, operations for these jobs are assigned to machines, and corresponding tools are allocated to the slots in the machines. The objective is to minimise system unbalance. A hybrid genetic algorithm is presented that addresses this problem. Computational comparison between the genetic algorithm and previous algorithms is presented
Production management in New Zealand: is education relevant to practice?
No full textPresents a report on a postal survey of production managers and production management academics carried out in New Zealand. The managers were asked questions about their tasks, responsibilities, and educational needs. The academics provided data on their teaching of production management. The survey particularly focused on the practical relevance of production management topics commonly taught in undergraduate courses of tertiary institutions. Survey results show that the practical relevance of production management education in New Zealand is significant, but there is room for improvement.</jats:p
Selection of dispatching rules in simulation-based scheduling of flexible manufacturing
No full textDiscrete-event simulation has been proposed as a tool for the real-time selection of dispatching rules in the scheduling of flexible manufacturing systems (FMS). In this approach, a look-ahead simulation is used to predict the trajectory of the system under different dispatching rules. Then a rule is selected for use in the FMS, based on the performance criterion associated with each trajectory. However, this raises the issue of the criterion to be used for the selection of the rules. A simulation model of an FMS was used to test the effect of rule selection procedure on two performance measures. This simulator was run using four scheduling policies and the performance of the FMS was measured. The main finding of this research is that the use of global criteria gives better results than the use of local criteria
A genetic algorithm for a bicriteria supplier selection problem
No full textIn this paper, we discuss the problem of selecting suppliers for an organisation, where a number of suppliers have made price offers for supply of items, but have limited capacity. Selecting the cheapest combination of suppliers is a straightforward matter, but purchasers often have a dual goal of lowering the number of suppliers they deal with. This second goal makes this issue a bicriteria problem – minimisation of cost and minimisation of the number of suppliers. We present a mixed integer programming (MIP) model for this scenario. Quality and delivery performance are modelled as constraints. Smaller instances of this model may be solved using an MIP solver, but large instances will require a heuristic. We present a multi-population genetic algorithm for generating Pareto-optimal solutions of the problem. The performance of this algorithm is compared against MIP solutions and Monte Carlo solutions
A genetic algorithm for a bicriteria supplier selection problem
Get PDFAbstract In this paper, we discuss the problem of selecting suppliers for an organisation, where a number of suppliers have made price offers for supply of items, but have limited capacity. Selecting the cheapest combination of suppliers is a straightforward matter, but purchasers often have a dual goal of lowering the number of suppliers they deal with. This second goal makes this issue a bicriteria problem -minimisation of cost and minimisation of the number of suppliers. We present a mixed integer programming (MIP) model for this scenario. Quality and delivery performance are modelled as constraints. Smaller instances of this model may be solved using an MIP solver, but large instances will require a heuristic. We present a multipopulation genetic algorithm for generating Pareto-optimal solutions of the problem. The performance of this algorithm is compared against MIP solutions and Monte Carlo solutions
