Branch and Bound Algorithm for Multiprocessor Scheduling

The multiprocessor task graph scheduling problem has been extensively studied asacademic optimization problem which occurs in optimizing the execution time of parallelalgorithm with parallel computer. The problem is already being known as one of the NPhardproblems. There are many good approaches made with many optimizing algorithmto find out the optimum solution for this problem with less computational time. One ofthem is branch and bound algorithm.In this paper, we propose a branch and bound algorithm for the multiprocessor schedulingproblem. We investigate the algorithm by comparing two different lower bounds withtheir computational costs and the size of the pruned tree.Several experiments are made with small set of problems and results are compared indifferent sections.

Simulation and optimisation techniques for sawmill yard operation : A literature review

Increasing costs and competitive business strategies are pushing sawmill enterprises to make an effort for optimization of their process management. Organizational decisions mainly concentrate on performance and reduction of operational costs in order to maintain profit margins. Although many efforts have been made, effective utilization of resources, optimal planning and maximum productivity in sawmill are still challenging to sawmill industries. Many researchers proposed the simulation models in combination with optimization techniques to address problems of integrated logistics optimization. The combination of simulation and optimization technique identifies the optimal strategy by simulating all complex behaviours of the system under consideration including objectives and constraints. During the past decade, an enormous number of studies were conducted to simulate operational inefficiencies in order to find optimal solutions. This paper gives a review on recent developments and challenges associated with simulation and optimization techniques. It was believed that the review would provide a perfect ground to the authors in pursuing further work in optimizing sawmill yard operations.

Module property verification : A method to plan and perform quality verifications in modular architectures

Modular product architectures have generated numerous benefits for companies in terms of cost, lead-time and quality. The defined interfaces and the module’s properties decrease the effort to develop new product variants, and provide an opportunity to perform parallel tasks in design, manufacturing and assembly. The background of this thesis is that companies perform verifications (tests, inspections and controls) of products late, when most of the parts have been assembled. This extends the lead-time to delivery and ruins benefits from a modular product architecture; specifically when the verifications are extensive and the frequency of detected defects is high. Due to the number of product variants obtained from the modular product architecture, verifications must handle a wide range of equipment, instructions and goal values to ensure that high quality products can be delivered. As a result, the total benefits from a modular product architecture are difficult to achieve. This thesis describes a method for planning and performing verifications within a modular product architecture. The method supports companies by utilizing the defined modules for verifications already at module level, so called MPV (Module Property Verification). With MPV, defects are detected at an earlier point, compared to verification of a complete product, and the number of verifications is decreased. The MPV method is built up of three phases. In Phase A, candidate modules are evaluated on the basis of costs and lead-time of the verifications and the repair of defects. An MPV-index is obtained which quantifies the module and indicates if the module should be verified at product level or by MPV. In Phase B, the interface interaction between the modules is evaluated, as well as the distribution of properties among the modules. The purpose is to evaluate the extent to which supplementary verifications at product level is needed. Phase C supports a selection of the final verification strategy. The cost and lead-time for the supplementary verifications are considered together with the results from Phase A and B. The MPV method is based on a set of qualitative and quantitative measures and tools which provide an overview and support the achievement of cost and time efficient company specific verifications. A practical application in industry shows how the MPV method can be used, and the subsequent benefits

Microstructural, Mechanical and Tribological Characterisation of CVD and PVD Coatings for Metal Cutting Applications

The present thesis focuses on characterisation of microstructure and the resulting mechanical and tribological properties of CVD and PVD coatings used in metal cutting applications. These thin and hard coatings are designed to improve the tribological performance of cutting tools which in metal cutting operations may result in improved cutting performance, lower energy consumption, lower production costs and lower impact on the environment.  In order to increase the understanding of the tribological behaviour of the coating systems a number of friction and wear tests have been performed and evaluated by post-test microscopy and surface analysis. Much of the work has focused on coating cohesive and adhesive strength, surface fatigue resistance, abrasive wear resistance and friction and wear behaviour under sliding contact and metal cutting conditions. The results show that the CVD deposition of accurate crystallographic phases, e.g. α-Al2O3 rather than κ-Al2O3, textures and multilayer structures can increase the wear resistance of Al2O3. However, the characteristics of the interfaces, e.g. topography as well as interfacial porosity, have a strong impact on coating adhesion and consequently on the resulting properties.  Through the deposition of well designed bonding and template layer structures the above problems may be eliminated. Also, the presence of macro-particles in PVD coatings may have a significant impact on the interfacial adhesive strength, increasing the tendency to coating spalling and lowering the surface fatigue resistance, as well as increasing the friction in sliding contacts. Finally, the CVD-Al2O3 coating topography influences the contact conditions in sliding as well as in metal cutting. In summary, the work illuminates the importance of understanding the relationships between deposition process parameters, composition and microstructure, resulting properties and tribological performance of CVD and PVD coatings and how this knowledge can be used to develop the coating materials of tomorrow.

Perceived Work-related Factors and Turnover Intention : A Case Study of a South Korean Construction Company

Purpose – Employee turnover entails considerable costs and is a major problem for the construction industry. By creating an extensive framework, this study aims to examine whether perceived work-related factors affect turnover intention in South Korean construction companies. Research design – The paper is based on the results of a questionnaire of 136 employees that was conducted and provided by a Korean construction company. Research hypotheses were tested via correlation analyses. The most influencing work-related factors, as well as differences among job levels, were determined by multiple regression analyses. Findings – Communication, immediate leaders, organizational commitment, and organizational pride substantially affect turnover intentions. All of these factors can be considered as relational factors. The most influencing factors differ among job levels. Discussion/practical implications – Immediate leaders should be aware of their role in retaining employees and enhance communication, organizational commitment and pride. This study shows how the importance of certain variables differs for groups of employees. Theoretical implications/limitations– This study is based on a sample of employees from a Korean construction company. Therefore, the generalizability of the findings has to be tested. Future research should test the proposed framework with other factors or resources. Originality/value – This study shed light on the turnover subject in the South Korean construction industry. It shows that different factors can influence turnover intention among job levels. A framework was created, which is based on 16 work-related factors including organizational factors, HRM practices and job attitudes.

Perceived Work-related Factors and Turnover Intention : - A Case Study of a South Korean Construction Company

Purpose – Employee turnover entails considerable costs and is a major problem for the construction industry. By creating an extensive framework, this study aims to examine whether perceived work-related factors affect turnover intention in South Korean construction companies. Research design – The paper is based on the results of a questionnaire of 136 employees that was conducted and provided by a Korean construction company. Research hypotheses were tested via correlation analyses. The most influencing work-related factors, as well as differences among job levels, were determined by multiple regression analyses. Findings – Communication, immediate leaders, organizational commitment, and organizational pride substantially affect turnover intentions. All of these factors can be considered as relational factors. The most influencing factors differ among job levels. Discussion/practical implications – Immediate leaders should be aware of their role in retaining employees and enhance communication, organizational commitment and pride. This study shows how the importance of certain variables differs for groups of employees. Theoretical implications/limitations– This study is based on a sample of employees from a Korean construction company. Therefore, the generalizability of the findings has to be tested. Future research should test the proposed framework with other factors or resources. Originality/value – This study shed light on the turnover subject in the South Korean construction industry. It shows that different factors can influence turnover intention among job levels. A framework was created, which is based on 16 work-related factors including organizational factors, HRM practices and job attitudes.