Minimizing the sum of flow times with batching and delivery in a supply chain

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The aim of this thesis is to study one of the classical scheduling objectives that is of minimizing the sum of flow times, in the context of a supply chain network. We consider the situation that a supplier schedules a set of jobs for delivery in batches to several manufacturers, who in tum have to schedule and deliver jobs in batches to several customers. The individual problem from the viewpoint of supplier and manufacturers will be considered separately. The decision problem faced by the supplier is that of minimizing the sum of flow time and delivery cost of a set of jobs to be processed on a single machine for delivery in batches to manufacturers. The problem from the viewpoint of manufacturer is similar to the supplier's problem and the only difference is that the scheduling, batching and delivery decisions made by the supplier define a release date for each job, before which the manufacturer cannot start the processing of that job. Also a combined problem in the light of cooperation between the supplier and manufacturer will be considered. The objective of the combined problem is to find the best scheduling, batching, and delivery decisions that benefit the entire system including the supplier and manufacturer. Structural properties of each problem are investigated and used to devise a branch and bound solution scheme. Computational experience shows significant improvements over existing algorithms and also shows that cooperation between a supplier and a manufacturer reduces the total system cost of up to 12.35%, while theoretically the reduction of up to 20% can be achieved for special cases

Identifying the critical success factors of organization with Analytic Hierarchy Process approach (case study – Iran Argham Company)

In today’s challenging and complex world, organizations success depends on productivity, continuous improvement in all dimensions and reforming the pattern of resource utilization. Therefore, organizations, while considering restrictions, should focus on the most effective factors or so-called critical success factors. This paper intends to identify and prioritize the critical success factors, among other, factors influencing success of the organization, using hierarchical analysis and application of tools and related software. Analytic Hierarchy Process provides the possibility to compare the factors via creating matrix of paired comparisons. The case study in this research includes identifying the critical success factors and prioritizing them in Iran Argham Company. Finally, among the results presented, five critical success factors are identified from the forty influential factors. These five factors account for about seventy percent of the organization’s success. It should be noted that most studies conducted in this area focuse on the certain processes and special systems rather than study on the organization as a whole unit. This model can also be generalized to all organizations, including SMEs, and would provide remarkably valuable approaches, especially in competitive markets. Keywords: key success factors, strategic management, critical success factors, AHP. JEL Classification: M10, M14, L21, C4

Minimizing the sum of flow times with batching and delivery in a supply chain

The aim of this thesis is to study one of the classical scheduling objectives that is of minimizing the sum of flow times, in the context of a supply chain network. We consider the situation that a supplier schedules a set of jobs for delivery in batches to several manufacturers, who in tum have to schedule and deliver jobs in batches to several customers. The individual problem from the viewpoint of supplier and manufacturers will be considered separately. The decision problem faced by the supplier is that of minimizing the sum of flow time and delivery cost of a set of jobs to be processed on a single machine for delivery in batches to manufacturers. The problem from the viewpoint of manufacturer is similar to the supplier's problem and the only difference is that the scheduling, batching and delivery decisions made by the supplier define a release date for each job, before which the manufacturer cannot start the processing of that job. Also a combined problem in the light of cooperation between the supplier and manufacturer will be considered. The objective of the combined problem is to find the best scheduling, batching, and delivery decisions that benefit the entire system including the supplier and manufacturer. Structural properties of each problem are investigated and used to devise a branch and bound solution scheme. Computational experience shows significant improvements over existing algorithms and also shows that cooperation between a supplier and a manufacturer reduces the total system cost of up to 12.35%, while theoretically the reduction of up to 20% can be achieved for special cases.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

A TWO-STAGE GREEDY HEURISTIC FOR A FLOWSHOP SCHEDULING PROBLEM UNDER TIME-OF-USE ELECTRICITY TARIFFS

This paper studies a two-machine flowshop scheduling problem under time-dependent electricity tariffs, in which electricity prices may vary from time to time throughout the day. The main issue is to assign a set of jobs to available time slots with different electricity prices to minimise the total resource cost required for processing the jobs. The main contribution of this work is two-fold. First, a new continuous-time mixed-integer linear programming (MILP) model is proposed for the problem. Second, a two-stage greedy heuristic is developed. A computational experiment on randomly generated instances demonstrates that the greedy algorithm can improve the objective function by almost 40 percent. The algorithm can be applied by production managers to scheduling jobs in a flowshop under time-of-use (TOU) electricity tariffs to save electricity costs

A new outsourcing framework: A case study of educational institution activities

During the past two decades, there have been growing interests on reducing different activities using outsourcing activities. Outsourcing allows us to focus only on value added activities, which helps reduce the size of organizations. In this paper, we present a new framework based on PMBOK, which determines and ranks important activities for outsourcing. The proposed model of this paper is implemented for a real-world case study in educational system. We have distributed a questionnaire among some decision makers and asked them about their opinions on outsourcing activities on Likert scale. We have compared the relative importance of four major activities including educational activities, research and development, administration and services. The results indicate that general services are the most important activities, which are suitable for partnership followed by administration activities. Educational and research activities and development are in lower important activities

Heuristic for Stochastic Online Flowshop Problem with Preemption Penalties

The deterministic flowshop model is one of the most widely studied problems; whereas its stochastic equivalent has remained a challenge. Furthermore, the preemptive online stochastic flowshop problem has received much less attention, and most of the previous researches have considered a nonpreemptive version. Moreover, little attention has been devoted to the problems where a certain time penalty is incurred when preemption is allowed. This paper examines the preemptive stochastic online flowshop with the objective of minimizing the expected makespan. All the jobs arrive overtime, which means that the existence and the parameters of each job are unknown until its release date. The processing time of the jobs is stochastic and actual processing time is unknown until completion of the job. A heuristic procedure for this problem is presented, which is applicable whenever the job processing times are characterized by their means and standard deviation. The performance of the proposed heuristic method is explored using some numerical examples

A mathematical model for weighted tardy jobs scheduling problem with a batched delivery system A R T I C L E I N F O A B S T R A C T

This study investigates minimizing the number of weighted tardy jobs on a single machine when jobs are delivered to either customers or next station in various size batches. In real world, this issue may happen within a supply chain in which delivering goods to customers entails costs. Under such circumstances, keeping completed jobs to deliver in batches may result in reducing delivery costs; nevertheless, it may add to the tardy jobs, which in turn leads to higher costs. In literature review, minimizing the number of weighted tardy jobs is known as NP-Hard problem, so the present issue aiming at minimizing the costs of delivering, in addition to the aforementioned objective function, remains an NP-Hard problem. In this study, the issue is assessed where the customers are numerous, and a mathematical model is presented. We also present a meta-heuristic method based on simulated annealing (SA) and the performance of the SA is examined versus exact solutions