greedy algorithm
در نشریات گروه صنایع-
International Journal of Research in Industrial Engineering, Volume:10 Issue: 2, Spring 2021, PP 155 -164
This paper presented greedy algorithm for solving student allocation problem that has arisen in internship program. In internship program, engineering students stay one semester in industries which are located across the country and teachers visit students once/twice for supervision during the program. As the industries scatter across the country, teachers spend long time on travel. And this results in wastage of teachers working time and money spent for transport. Therefore, allocating students to universities near the internship location extensively reduces the transport time and money spent for transport. For the current study, we consider 4th mechanical engineering students who are currently working in the industry. The proposed approach extensively decrease the distance traveled from 23,210 km to 2,488.8 km and the time spent on the road from 397 hrs. 40 min to 51 hrs. 30 min. and finally, the results obtained from the greedy algorithm is compared with other heuristics (i.e., Genetic algorithm and Particle swarm optimization) and the greedy algorithm outperforms the other methods.
Keywords: Internship Program, Students, Reallocation, Greedy Algorithm -
Journal of Quality Engineering and Production Optimization, Volume:4 Issue: 2, Winter Spring 2019, PP 189 -208
Transportation in economic systems such as services, production and distribution enjoys a special and important position and provides a significant portion of the country's gross domestic product. Improvements in transportation system mean improvements in the traveling routes and the elimination of unnecessary distances in any system. The Vehicle Routing Problem (VRP) is one of the practical concepts in the field of investigation and many attempts have been made by researchers in this area. Due to the importance of transportation issues in the real world and the status of these issues in the types of existing systems. In this paper, we investigate the Vehicle Routing Problem with Time Window (VRPTW) and provide a solution for it. The problem of routing vehicles with a time window is an extension of the problem of routing vehicles with limited capacity (CVRP) in which servicing must be done in a specific time window. The purpose of this problem is to optimize the route for each vehicle so as to minimize the total cost of the route and the number of vehicles used, and ultimately maximize customer satisfaction. In the paper, a hybrid method based on cuckoo search and greedy algorithm is proposed to solve the problem of VRPTW. For the cost function, different criteria have been used that are within the framework of the VRPTW problem within hard and soft constraints. In order to evaluate the proposed method, the dataset is used in different sizes. The proposed method is significantly higher compared to similar methods.
Keywords: Vehicle routing, Time Window, Cuckoo Search, Greedy Algorithm, Solomon Dataset -
In last decades, mobile factories have been used due to their high production capability, carrying their equipment and covering rough and uneven routes. Nowadays, more companies use mobile factories with the aim of reducing the transportation and manufacturing costs. The mobile factory must travel between the suppliers, visit all of them in each time period and return to the initial location of the mobile factory. In this paper, we present an integer nonlinear programming model for production scheduling and routing of mobile factory with the aim of maximization of profit. This problem is similar to the well-known Traveling Salesman Problem (TSP) which is an NP-hard problem. Also at each supplier, the scheduling problem for production is NP-hard. After linearization, we proposed a heuristic greedy algorithm. The efficiency of this heuristic algorithm is analyzed using the computational studies on 540 randomly generated test instances. Finally, the sensitivity analysis of the production cost, transportation cost and relocation cost was conducted.Keywords: Mobile Factory, Routing, Production Scheduling, Greedy Algorithm
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مدیریت ریسک یکی از بخش های تاثیرگذار مدیریت پروژه است که ریسک های مربوط به پروژه را شناسایی و ارزیابی می کند و به آن پاسخ می دهد. در چند سال اخیر، با وجود انتشار تحقیقات مختلف در مبحث پاسخ به ریسک پروژه، ابزار و روش های معدودی در این زمینه ارائه شده است. از این رو، در این پژوهش یک مدل بهینه سازی پاسخ به ریسک پروژه پیشنهاد شده است که به دنبال بهینه سازی دو معیار کلیدی زمان و هزینه پروژه است. مدل دارای دو هدف است که یک هدف، حداقل سازی زیان کل مورد انتظار، شامل هزینه اجرای اقدام ها و آثار نامطلوب ریسک بر هزینه پروژه و هدف دیگر کمینه سازی اثر زمانی ریسک (بیشینه کردن معیار استواری) با توجه به معیار شناوری آزاد فعالیت هاست. در این مدل، اقداماتی برای کاهش ریسک انتخاب می شود که میزان اثر زمانی آن ها بر زمان هر فعالیت بیشتر از شناوری آزاد آن است. درادامه، سه روش حل دقیق، ابتکاری و فرا ابتکاری پیشنهاد شده است که با ایجاد ده پروژه در سه دسته با مقیاس کوچک، متوسط و بزرگ و حل مسائل از سه روش پیشنهادی، نتایج مقایسه شده است.کلید واژگان: الگوریتم حلقوی، الگوریتم ژنتیک، پاسخ به ریسک پروژه، رویکرد استوار، شناوری فعالیت، مدل بهینه سازیRisk management is one of the most important aspects of project management that identifies, assesses and responds to project risks. Although many papers have been published in project risk response, presented tools and methods are poor. Hence, in this paper, we present an optimization model to respond project risk that seeks to optimize two key criteria of project: cost and time. The proposed model has two objectives that one of them is minimization of the total cost that include abatement action cost and the cost of risk loss on project, and the other one is minimization of the time loss of risk (i.e., maximization robust measure) according to a free float activitys measure. The model tries to choose abatement actions of risk that loss of them on time activity is greater than free float activity. Subsequently, three solution methods (i.e., exact, heuristic and meta-heuristic) are proposed. Then we create ten sample projects in three categories (i.e., small, medium and large scale) and solve the problems with the proposed methods and compare the results.Keywords: Genetic algorithm, Greedy algorithm, Project risk response, Robust optimization model
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