Sharif Digital Repository

Facility Layout Problem (FLP) is known as one of the classical problems in industrial engineering which have acquired high attractiveness to researchers. Therefore, in this study, a practical mathematical model is formulated and solved
In order to have a real and practical model, robust optimization is applied to FLP. Therefore, it is supposed to have dynamic values for departments' dimensions. This assumption is very critical to generate an effective and acceptable layout. We consider that each dimension of a department can be changed in a given interval. Due to this assumption, we introduce two new parameters which are called width and length deviation coefficients, respectively.... 

reparedness and emergency procedure be devised in the event of,and prior to,a disaster. One of these disastersoften accompanying byhuge damages, losses and casualtiesisanearthquake. After such a disaster, several governmental and non-governmental organizations usually start relief operations. They commonly pursue their own agendas and use their own facilities and capabilities to help the people affected without pursuing a central plan. These disintegrated behaviors of involved organizations generate contradictory responses and result in either wasted resources or preventing equitable service for all affected people. Due tothe abovefact, this dissertation proposes amodel for improving... 

Facility Layout Problem is one of the classic problems with the goal of arranging facilities with respect to the objective function and it’s been the subject of many researches for many years. By progressive development of industrial units in recent years and the lack of space especially in major cities, using multi-floor buildings can be a suitable solution. In literature, a few researches on this kind of layout problems are done. Maybe the main reason is difficulties of modeling. In this problem, with regard to objective function, interior and between floors flow and some predefined constraints, a suitable floor and place for each facility or department is determined. On the other hand, in... 

Studying the major effects of facility layout on competitive abilities has been a field of interest for researchers. Selection of production layout is amongst the most important decisions because it has a major role on the efficiency of a company like the ability of quick respond to customers’ diverse needs.
In this study we intend to obtain a ranking of production layouts considering agility in production which leads to responding quickly to the diversity of demand. Considering the nature of a decision making problem, we use PSI method. This is a multi attribute decision making method in which there is no need for considering the relative importance between the attributes. The main... 

An α-labeling of a graph is a special case of graceful labeling which was introduced in the late 1960’s. Despite the large number of papers published on this subject in literature, there are few particular techniques to find labeling of graphs. There are still many open problems on this subject, some of which are well-known in Graph Theory. In this thesis, first we present and solve several new mathematical and constraint programming models to find α-labeling of 2-regular graphs. Then, a comparison between their results is discussed. Since, proposed models can only label small size graphs; a tabu search algorithm for labeling the big size 2-regular graphs has been developed. By labeling... 

As time has passed, the cost of maintaining expert human resources has been increasing worldwide; as a result, factories and stakeholder has sought ways to exploit the expertise of their human resources as much as possible so they can reduce their costs and, of course, raise their profits. To achieve this, managers decided to assign their human resources to tasks that demands their expertise and knowledge and therefore provides added value for their companies; nevertheless, this decision needs proper alternatives to do routine and predetermined jobs as substitutions for expert human resources.As the technology and the science has been growing day by day, the use of robots has been extremely... 

Nowadays the popularity of renewable energy is increasing due to its clean and inexhaustible nature. Also, if the local potential of each area is used, there is no cost to connect to electricity network. But these energies have low reliability due to their oscillating nature. To solve this problem, it is proposed to use systems based on several sources of energy called hybrid systems. In this research, a mathematical model is proposed to design a renewable hybrid system that minimizes the present value of costs while maximizing system’s reliability. To consider the uncertainty in the solar radiation data and energy demand, Bertsimas’s robust model is applied to our model. In which variables... 

In this thesis the capacity and flow assignment problems in worldwide webs is considered in order to minimize the total cost of networks and delays in network links. The main result of this problem is increasing the speed of message transmission and providing better quality of service delivery for network users. For pursuing these goals, Recursive Artificial Neural Networks is proposed for solving the problem and because of their high power and accuracy in reaching optimal solutions, they are convergent to optimal solutions very well. The method is tested on four different topologies and the results show that Recursive Artificial Neural Networks have high efficiency to reach optimal... 

Regarding recent progress in the field of decision theory and the discovery of the important factors in human decision making, it is suggested by researchers to build up models that take all of, or at least most of, those factors into account simultaneously. In this research, first, we present some important achievements in the field of decision theory then develop a model based on these factors. Therefore, we focus on influential factors in human decision making, especially recent ones in neuroeconomics and mathematical models are presented to describe their effects. Then a descriptive model is proposed and changed it to a prescriptive model by adding some assumptions and standard charts.... 

Among scientific fields of study, mathematical programming has high status and its importance has led researchers to develop accurate models and effective solving approaches to addressing optimization problems. In particular, meta-heuristic algorithms are approximate methods for solving optimization problems whereby good (not necessarily optimum) solutions can be generated via their implementation. In this study, we propose a population-based meta-heuristic algorithm according to chemotherapy method to cure cancers that mainly search the infeasible region. As in chemotherapy, Chemotherapy Science Algorithm (CSA) tries to kill inappropriate solutions (cancers and bad cells of the human body);... 

According to the expanding of technology and information technology, organizations today are forced to collaborate and share knowledge with each other in order to obtain competitive advantages, and have innovation. This information sharing, in addition to its benefits, makes organizations vulnerable to loss of information in various ways by hackers, competitors or other agents through security breaches.In this research, the issue of protecting IT-based organizations from cyberattacks is discussed by using a concept of attack graphs interdiction. At first, after defining the problem precisely, it is modeled as a bi-level mathematical programming. In this problem, the attacker is looking for... 

Graph sum coloring problem is a special case of graph vertex coloring. Because of its applications in practical areas, especially in scheduling, many researchers have been attracted to it. In recent years, several heuristic and metaheuristic algorithms were applied to sum coloring problem. In this research a heuristic algorithm based on mini-max ant system and simulated annealing metaheuristics is used for graph sum coloring problem. This algorithm is tested on random graphs used in the literature and compared with prior algorithms. Results show that in many cases our proposed algorithm reaches the best known results or improves them  

Today the losses due to road accidents in Iran are very high. For this reason, it is essential to investigate the effective factors on the road accidents. Therefore, at first, there is a need to identify the solutions of reducing the accidents, their priories and finally their efficiency improvement. In this research, using Hierarchical Analysis Method, the solutions to reduce the accidents are prioritized and then In order to conduct the AHP analysis, Expert Choice software was chosen. According to research findings, the factors that lead to accidents are categorized as: Human factors, road environmental factors, vehicle, natural factors and managerial factors. The findings show that in... 

Peoples need financial resources to improve their quality of life, and companies need them to progress and increase their comparative advantage. Borrowing is one of the most popular methods of financing. Peer-to-peer lending, also known as "marketplace" or "social" lending, is a novel form of intermediation that expunges the role of financial institutions (like banks) as an intermediary and allows entities (individuals or businesses) to raise loans directly from other entities. This lending platform can provide better quality services to borrowers (by quickly providing a simple loan application process through a transparent and flexible portal) and lenders (by managing their funding and live... 

Parallel machine scheduling problems are the decision-making process of allocating limited resources to activities over time. These issues have attracted a lot of attention in the past decades based on their applications in the real world. It can be discussed about the application of parallel machine scheduling problems in computer processing, production lines and multi-stage systems as examples of areas where parallel machine is observed. Most of the research on parallel machine scheduling has focused on the optimization of a single criterion such as total or average task completion time, total completion time with different weights, sum of penalty or tardiness penalty, total number of... 

This study offers a framework to manage mass vaccination programs in response to an outbreak in a city. Compared to previous studies, we consider more operational challenges in the vaccination process; for example, transshipment between vaccinations units and availability of second doses. Our objective function is based on the risk of unvaccinated individuals. Therefore, the model aims at favoring those places in the city where the risk of unvaccinated people is high. Using different kinds of vaccines is another factor that our mathematical model includes. Vaccines are categorized into single-dose and double-dose classes. In this regard, the balanced access to different vaccine types is of... 

Examples from recent years, such as Covid-19 disease and earthquakes, show that disasters can have devastating effects on a community.These disasters are divided into two categories: expected and unexpected. decision makers cannot easily determine the time, severity and effects of them. Therefore, they must coordinate their decisions in the pre-disaster and post-disaster stages according to the incomplete information available, and according to the dynamics of the situation, quickly understand and interpret the connections between different decisions. Among the various approaches, the decision support system can explore the variable and unpredictable nature of such issues and enable decision...