جستجوی مقالات مرتبط با کلیدواژه « integer linear programming » در نشریات گروه « مدیریت »

Periodical services are scheduled in various methods throughout different industries and services. Customers or clients periodically visit institutions or service providers to request for a service. Examples are patients referring to physicians or university students to lecturers. This paper proposes a novel model for the scheduling of the periodical services that university students may inquire from their lecturers. The timing of the schedule should accommodate an even distribution of office visits, intervals between the visits, and continual visits, which may require longer time slots. Although the problem has a complex structure, a pure linear integer model is formulated to yield a satisfactory schedule. The solution is verified using two numerical examples and one real example on LINGO (version 17). The results indicate that the model enjoys an acceptable processing time while meeting all constraints, and may be employed successfully on a large scale.

The selection of project portfolio is the main problem in project-based organizations. In project selection, optimized decision to maximizing utilization of limited resources and achieving organizational goals by considering restrictions are important. Therefore, to facilitate project portfolio selection in project-based organizations, an efficient model is proposed that is able to consider limitations, goals, and priorities of the organization in selecting the optimal combination of projects. The proposed model is a hybrid and flexible one which, including four main steps. First, with initial screening, to save time and money by using non-compensatory method, some of the poor candidate options are deleted. Then, due to multi-criteria nature of the problem, qualitative and quantitative criteria, and uncertainty of data in real world, the projects are ranked using fuzzy analytic hierarchy processes and uncertain judgments of decision-makers. To generate project baskets, integer linear programming (ILP), backpack model, is employed modifying the coefficients of the objective function of each project to preserve multi-criteria rating of projects, and then evaluate and rank the baskets. To validate the proposed model, we have carried out selection of project portfolio in the oil refining industry.

An integer linear programming model for university courses timetabling is proposed here. In order to reduce the number of decisive variables, a combination of a course, a professor schedule and the students ‘group was defined as an activity. In this context, the two integer programming models namely the activity-based model and a two-phase activity-based model were proposed. In the first model, all activities were scheduled based on the number of required weekly sessions in the weekdays intervals; however, in the second model, classes and training courses were determined according to the planned sessions considering their special restrictions. These models were formulated based on the process of assigning the university courses within specific intervals throughout the week considering fierce constraints for a given semester in the department of Economics at University of Isfahan. All regulation concerning the courses timetable of a semester were formulated in GAMS software. Then, 239 courses were successfully scheduled using the two-phase activity-based model in only 9 minutes and 16 seconds

Course timetabling is an important branch of the general scheduling problem. The course timetabling problem as a step in the course planning process in universities is one of the challenges faced by managers in the field of education. The problem is defined as assigning university courses to specific periods throughout a week for a given semester while satisfying specific constraints. In this study, we present two novel binary integer linear programming models for the university timetabling problem. Using a GAMS IP Solver, several experiments through each model are solved and the results (the number of the decision variables and solution time) are compared and analyzed. The computational comparison indicates that the second model can be used for modeling large-scaled problems and has less computational and size complexity. Therefore, the second model is applied to optimal scheduling the courses planned for the faculty of administrative science and economics (ASE) at Isfahan University for one semester and the results consist of table of courses planned for teachers, students groups, rooms and workdays are presented

In the industrial firms, setting an appropriate scheduling of production is one of the most important tasks of the management, so that a producer can make the most of possible utility. In recent years a new kind of problems has been detected that the main goal of its production planning, further than reducing the completion time of products, is to make different components of a producing package to be ready with a small time space. This paper presents an integer linear programming model to optimize the production planning for a multi-product system with identical parallel production lines that minimizes the summation of the time spaces between the completion times of various items of producing packages. A numerical example is given and solved and by comparing the results obtained from the model with results from two other objective functions, the efficiency of the proposed model investigated in the real world.

Proposing a New Approach for Supplier Selection Based on Kraljic’s Model Using FMEA and Integer Linear ProgrammingIn recent years, numerous methods have been proposed to deal with supplier evaluation and selection problem, but a point which has been usually neglected by researchers is the role of purchasing items. The aim of this paper is to propose an integrated approach to select suppliers and allocate orders on the basis of the nature of the purchasing items which means that this issue plays an important role in supplier selection and order allocation. Therefore, items are first categorized according to the Kraljic’s model by the use of FMEA technique. Then, suppliers are categorized and evaluated in four phases with respect to different types of purchasing items (Strategic, Bottleneck, Leverage and Routine). Finally, an integer linear programming is utilized to allocate purchasing orders to suppliers. Furthermore, an empirical example is conducted to illustrate the stage of proposed approach. Results imply that ranking of suppliers and allocation of purchasing items based on the nature of purchasing items will create more capabilities in managing purchasing items and suppliers.