An application of a cocitation-analysis method to find further research possibilities on the area of scheduling problems

In this article we will give firstly a classification scheme of scheduling problems and their solving methods. The main aspects under examination are the following: machine and secondary resources, constraints, objective functions, uncertainty, mathematical models and adapted solution methods. In a second part, based on this scheme, we will examine a corpus of 60 main articles (1015 citation links were recorded in total) in scheduling literature from 1977 to 2009. The main purpose is to discover the underlying themes within the literature and to examine how they have evolved. To identify documents likely to be closely related, we are going to use the cocitation-based method of Greene et al. (2008). Our aim is to build a base of articles in order to extract the much developed research themes and find the less examined ones as well, and then try to discuss the reasons of the poorly investigation of some areas

Shop scheduling with availability constraints

Scheduling Theory studies planning and timetabling of various industrial and human activities and, therefore, is of constant scientific interest. Being a branch of Operational Research, Theory of Scheduling mostly deals with problems of practical interest which can be easily (from a mathematical point of view) solved by full enumeration and at the same time usually require enormous time to be solved optimally. Therefore, one attempts to develop algorithms for finding optimal or near optimal solutions of the problems under consideration in reasonable time. If the output of an algorithm is not always an optimal solution then the worst-case analysis of this algorithm is undertaken in order to estimate either a relative error or an absolute error that holds for any given instance of the problem. Scheduling problems which are usually considered in the literature assume that the processing facilities are constantly available throughout the planning period. However, in practice, the processing facility, e.g. a machine, a labour, etc. can become non-available due to various reasons, e.g. breakdowns, lunch breaks, holidays, maintenance work, etc. All these facts stimulate research in the area of scheduling with non-availability constraints. This branch of Scheduling Theory has recently received a lot of attention and a considerable number of research papers have been published. This thesis is fully dedicated to scheduling with non-availability constraints under various assumptions on the structure of the processing system and on the types of non-availability intervals

A survey of scheduling problems with setup times or costs

Author name used in this publication: C. T. NgAuthor name used in this publication: T. C. E. Cheng2007-2008 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe

An O(nlogn) algorithm for the two-machine flow shop problem with controllable machine speeds

Production Planning;Scheduling;produktieleer/ produktieplanning

Scheduling and Batching in Multi-Site Flexible Flow Shop Environments

Global competition and the customers demand for customized products with shorter due dates, marked the introduction of the Extended Enterprise. In this Extended Manufacturing Environment (EME), lean, virtual, networked and distributed enterprises collaborate to respond to the market demands. In this paper we study the influence of the batch size on Flexible Flow Shop makespan minimization problem FFC vertical bar vertical bar C-max for two multi-sites approaches, the FSBF (Flow Shop Based Factories) and the PMBF (Parallel-Machines Based Factories). The computational study demonstrates how the performance of the PMBF model decreases with the increase of batch size and determines the batch sizes in which the performance is similar.This work is supported by FEDER Funds through the “Programa Operacional Factores de Competitividade - COMPETE” program and by National Funds through FCT “Fundação para a Ciência e a Tecnologia” under the projects: “Projeto Estratégico–UI 252–2011–2012” reference PEstOE/EME/UI0252/2014, FCOMP-01-0124-FEDER-PEstOE/EEI/UI0760/2014.info:eu-repo/semantics/publishedVersio

Dynamic scheduling in a multi-product manufacturing system

To remain competitive in global marketplace, manufacturing companies need to improve their operational practices. One of the methods to increase competitiveness in manufacturing is by implementing proper scheduling system. This is important to enable job orders to be completed on time, minimize waiting time and maximize utilization of equipment and machineries. The dynamics of real manufacturing system are very complex in nature. Schedules developed based on deterministic algorithms are unable to effectively deal with uncertainties in demand and capacity. Significant differences can be found between planned schedules and actual schedule implementation. This study attempted to develop a scheduling system that is able to react quickly and reliably for accommodating changes in product demand and manufacturing capacity. A case study, 6 by 6 job shop scheduling problem was adapted with uncertainty elements added to the data sets. A simulation model was designed and implemented using ARENA simulation package to generate various job shop scheduling scenarios. Their performances were evaluated using scheduling rules, namely, first-in-first-out (FIFO), earliest due date (EDD), and shortest processing time (SPT). An artificial neural network (ANN) model was developed and trained using various scheduling scenarios generated by ARENA simulation. The experimental results suggest that the ANN scheduling model can provided moderately reliable prediction results for limited scenarios when predicting the number completed jobs, maximum flowtime, average machine utilization, and average length of queue. This study has provided better understanding on the effects of changes in demand and capacity on the job shop schedules. Areas for further study includes: (i) Fine tune the proposed ANN scheduling model (ii) Consider more variety of job shop environment (iii) Incorporate an expert system for interpretation of results. The theoretical framework proposed in this study can be used as a basis for further investigation

A Case study of value streams and lean implementation for a small print shop

The growing use of portable Internet devices (smart phones, iPads, laptops, etc.) has caused a huge shift toward digital distribution of content over traditional print processes. Poor economic conditions have contributed to increased customer price sensitivity and higher costs of goods involved in printing. These factors have changed demand for traditional printed products. Many printers have been unable to adapt to the new market environment, leading to dwindling profit margins and thousands of shop closures. Many strategies have been touted as the best way to stay profitable in the new market environment, including value-added services, new machinery, and software packages. However, according to the NAPL, productivity improvements, such as Lean, will now play the central role in differentiating the leaders in the industry. Printers, particularly small- and medium-sized printers, have been slow in their adoption of Lean or any of its variants. Lean organizations produce less waste (in its many forms), have improved product quality with shorter lead times, and have employees who are more engaged. Unfortunately small- and medium-sized printers are less likely to begin productivity improvement initiatives due to lack of knowledge, time commitment issues, fear of change, and lack of resources. The goal of this case study is to provide a theoretical framework and an in-depth example of how a small print shop\u27s production line operates and how to generate a tailored action plan for implementing Lean Manufacturing Principles. Specifically, the study focuses on the creation and usefulness of value stream mapping (graphically identifying the many forms of waste within a given system) for a small print shop. The case study is written with an easy to follow language as a guide to aide other small printers in creating their own Lean implementation plans. Careful, direct observation and documentation of a small 6-employee print shop occurred over a short period to gather data about the shop\u27s current value stream. Three product families were chosen for mapping: digital color printing, digital black and white printing, and offset press. Data collection focused on the workflow for jobs from creation to completion, how long each step takes, and how communication and materials move through production. Current value stream maps were generated using the collected data and were used to develop ideal and future maps. Detailed analysis of the current value stream revealed six key areas for the company to address that will provide the greatest benefit toward becoming Lean. The areas are: company culture, organization, bottlenecks, scheduling, communication and inventory. The following recommendations were made for the company to reduce waste and excess costs, improve value-added ratios, and reduce stress on employees. The current company culture has trust issues and does not encourage innovation. Management\u27s constant commitment to building and maintaining a new culture will be essential to creating change. Daily meetings and Kaizen events can help establish trust and empower employees to find and implement solutions. The shop floor needs 5S organization and will also require the implementation of an inventory system and reduction initiative. New suppliers may need to be found to accomplish just-in-time delivery. To alleviate bottlenecks in premedia and finishing, the graphic design stage should be removed from production to give production control the responsibilities of job scheduling and load leveling. Finishing then becomes the pacemaker process and dictates the flow, preventing push within the system. Kanban signals and supermarkets are recommended for maintaining a pull system. Communication across the shop can be improved through daily production meetings, utilizing exiting software for job tracking, establishing visual management boards, and establishing a sales department for handling customers