Sharif Digital Repository

Nowadays, radiation therapy is one of the most common methods for the cancer treatment. Intensity Modulated Radiation Therapy(IMRT) is a novel technique of radiation therapy that aims to delivere sufficient dose to cancerous tissues while sparing healthy organs. There are various uncertainties in radiation therapy problems, including uncertainty about device setup, device errors, interfraction and intrafraction motions. One of the most important uncertainties is the movement of the tumor during the treatment process(intrafraction motion), as this displacement may cause the cancer tissue to not receive sufficient dose and also to damage the healthy tissue due to a violation of their dose... 

Deteriorated old urban neighborhoods usually have no access to appropriate municipal services, and have small-sized buildings, densely populated areas, and earthquake-prone structures. Residents in these areas do not have the will and financial ability to renovate their aged properties. A questionnaire survey of the citizens living in the deteriorated areas of the City of Tehran showed that 80% of households do not have a positive monthly financial balance and cannot afford the cost of reconstructing their properties. Serious drawbacks of previous attempts to renovate deteriorated areas, including lack of adequate government funding, and adding to the dependence of local citizens on... 

Breast cancer has been one of the main causes of women's deaths in recent years. Today, various methods are used to treat this disease, among which intensity-modulated radiation therapy is one of the most common methods. The goal of radiation therapy is to destroy cancer cells while protecting the surrounding healthy tissues. In left breast cancer, due to the proximity of the heart and breast tissue, we are at risk of delivering an excessive dose to the heart and increasing cardiac complications after the treatment. In addition, due to the irregular and unpredictable breathing movements of the patient during the treatment and the resulting uncertainty, we face more challenges. In order to... 

There is a significant amount of data in the healthcare domain and it is unfeasible to process such volume of data manually in order to diagnose the diseases and develop a treatment method in the short term. Diabetes mellitus has attracted the attention of data miners for a couple of reasons among which significant effects on the health and well-being of the contracted people and the economic burdens on the health care system are of prime importance. Researchers are trying to find a statistical correlation between the causes of this disease and factors like patient's lifestyle, hereditary information, etc. The purpose of data mining is to discover rules that facilitate the early diagnosis... 

This research investigates permutation flow shop scheduling problems with sequence-dependent setup times with minimizing the number of tardy jobs as criterion (Fm|prmu, Sijk|ΣUj). A mixed integer linear programming model has been developed for the research problem. As the problem is shown to be NP-hard, several meta-heuristic algorithms based on tabu search (TS) and imperialist competitive algorithm are developed to heuristically solve the problem. In order to find the best meta-heuristic algorithm, random test problems, ranging in size from small, medium, to large are created and solved by the meta-heuristic algorithms. Then, a detailed statistical experiment, based on split-plot design is... 

Piping process is the most important part of industries projects which pay attention to construction and installation of industrial pipelines and its facilities. In the meantime, due to increasing demand of industrial units to construction and development projects, planing and scheduling the piping is necessary. We review and discuss various aspects of the piping process, optimization process and the related scheduling literature that is called Flexible Job Shop Scheduling Problem. Then, to solve the problem, considering the real world assumptions, a mathematical model, is developed and a heuristic algorithm is introduced. Also, in order to determine an appropriate bound for the optimal... 

The main goal of this thesis is to reduce the gap between the theoretical and actual project scheduling problems by introducing three problems and then proposing three different exact and meta-heuristic algorithms to solve them. These problems are as follows: the Resource-Constrained Project Scheduling Problem with Minimization of Total Weighted Resource Tardiness Penalty Costs (RCPSP-TWRTPC), the Resource-Constrained Project Scheduling Problem with Discounted Cash Flows of Weighted Earliness-Tardiness Costs (RCPSP-DCWET), and the Multi-Mode Resource-Constrained Project Scheduling Problem with Minimization of Total Weighted Resource Tardiness Penalty Costs (MRCPSP-TWRTPC). Also, we develop a... 

Graceful and α-valuation are the first labeling methods which was introduce in the late 1960. α-Vaulation of a graph is a special cases of graceful labeling. Despite of 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 research, a new mathematical integer model and two constraint programming models are presented for the graph valuation problem in the case of quadratic graphs. Then, a comparision between their results are discussed. The advantages of this model is linearity, independence from graph... 

A qualitative study has been conducted in order to identify evidence of bounded rationality in software engineers' career decision making. Tversky and Kahneman's heuristics and biases approach has been used as a theoretical framework of the study. The theoretical framework comprised four decision-making and judgment heuristics, i.e. availability, representativeness, anchoring and adjustment, and affect heuristic. The data were gathered through semi-structured interviews and analyzed using thematic analysis method. The final results revealed that software engineers did make use of heuristics in making career decisions. Several incidents of the use of availability, representativeness, and... 

Nowadays, the capital market has a significant impact on the economy of a country and causes economic dynamism and growth in gross production. Among the important phenomena in the stock market is stock pricing, the correctness or incorrectness of which has a significant role in the performance of the stock market and the value of companies. The stock price in the stock exchange represents the stock market value and usually represents the investment value of the shareholders. Forecasting the trend of the stock market is considered an important and necessary thing and has been given much attention, because the successful forecasting of the stock price may lead to attractive profits by making... 

Discrete network design problem is selecting a set of feasible projects among a set of candidate projects, considering a budget constraint in which user's cost is being minimized. Network design problem is one of the complicated problems in transportation science, since it is a bi-level problem in which the lower level is a traffic assignment problem and the upper level is finding the best set of arcs. Meta-heuristic algorithms can be used to solve this problem. Although, there is no guarantee to find the optimal solution by Meta-heuristic algorithms, but they find good solutions in short times. The purpose of this study is comparing the efficiency of three Meta-heuristic algorithms for... 

There are several algorithms in the literature to solve the problem of finding an optimal path between two points in a region. Such path satisfies certain constraints while optimizing the objective function. There are many factors in building, or finding, such paths in the real world, whose considerations complicate the solution procedure. This led the researchers to seriously consider meta-heuristics to solve the problem. This study hybridizes several suitable and effective meta-heuristic algorithms to solve the routing problem on a given topography. In this hybrid meta-heuristic algorithm an Ant System finds a horizontal path between the two points under considerations on the topography. A... 

This paper deals with no-wait open shop scheduling with sequence dependent setup times and release dates, minimizing total completion times. In spite of practibility of the problem, there is no substantial work dealing the problem. We present three formulation of the problem based on different decision variable paradigms and investigate some computational and efficacy aspects of the models. For large size problems, we first propose a novel encoding and decoding scheme of and present four particle Swarm Optimization (PSO)-based algorithms and four Tabu Search (TS)-base algorithms. To evaluate the performance of the algorithms we carry out two cpmputational experiments; in the first experiment... 

Distribution of goods by vehicle routing with split delivery and effective usage of trucks are two important problems which are useful separately and could be applied for different kinds of depots with different trucks to satisfy customers’ demand. Combination of these two NP-hard problems can play a great role to decrease transportation cost. Complexity of this problem is so much that we cannot solve big-size problems by exact methods or branch and bound method in limited time. We introduce metaheuristics methods such as Tabu Search, Simulated Annealing and Ant Colony Optimization which have been presented before, concisely. We present various constraints in routing and distribution,... 

Procurement field and supplier’s selection are key decisions in the supply chain in today's business environment.In this problem, both procurement and transportation costs are important. The Traveling Purchasing Problem (TPP) belongs to this field of study. In spite of many researches in the TPP, most of the researches are confined to one single purchaser. In this research, a new variant of Traveling Purchaser Problem is proposed with priority in purchasing. The priority policy is assumed for every single of products and the purchasers’ objective is to meet all of the demands according to their priority and vehicle's capacity in the lowest cost. In this regard, the purchaser has to buy the... 

In this research, the inventory – routing problem considering discount is studied. The problem consists of a supplier and several retailers who form a network of demand and supply points. In this research, offering discount to retailers is considered as an appropriate policy for reducing total costs of the supply chain. The supplier can augment the utility of her trucks by offering discounts and incentives to the retailers and delivering them amounts of product beyond their economic ordering quantity. This way, the supplier can have full truck-loads instead of lower than full truck-loads while delivering the demands of the retailers. This, can result in a decrease in transportation costs and... 

The rapid growth of e-commerce and home delivery has increased the number of vehicles on the streets. As a result of that, traffic congestion and, in return, air pollution have got worse. To prevent this trend, using electric vehicles is highly suggested, and in recent years, some companies have started using autonomous delivery robots. Since these robots can travel for a limited time, it is better to use them in conjunction with other vehicles, like vans. In this research, we propose a mixed-integer programming model to formulate a two-echelon time-dependent vehicle routing problem with simultaneous pick-up and delivery. In the first echelon, vans travel from a central depot to parking and... 

For offshore oil production, oil facilities should be continuously provided. The focus of this research is on the problems associated with a fleet of vessels from central depot(s) that are periodically utilized to serve wells and wellhead platforms with different demands and time limits. Iranian Offshore Oil Company, the largest offshore oil producer in Iran, was selected as a case study in this thesis. The main objectives is twofold. The first objective in the current study is to plan periodic routing of mobile wellhead servants and supporter vessels, as providers of general and technical services for the equipment on wellhead platforms. In some periods, the mobile wellhead servants require... 

This thesis presents an inventory control system which is based on Meta-heuristic Algorithms.In this thesis we will optimize the input values of our tree-echelon inventory model (keeping costs,stock worth,reorder costs,...) with these Algorithms. The presented method is able to determine the optimal stock level, costs of system and number of shipments in the system. The method is basically a decision support system (DES) and it is able to provide the order scheduling parameters of goods at operational level. The aim of the current research is to demonstrate that a Meta-heuristic algorithmis capable of solving complex inventory problems and with future improvements it is able to achieve... 

Pricing and Revenue Management in systems that offer services in subscription as well as pay-per-use format simultaneously is one of the most significant challenges in service companies. One of the main criteria in these systems is keeping the loyal customers and attracting more subscribers. Pricing and capacity allocation are decisions to be made in such systems considering customer’s behavior. In this research, we consider a service system with subscription and pay per use options to analyze the price and capacity allocation based on customer’s bahvior. The Loss Aversion theory is assumed for customer’s behavior and its effect on decisions is analyzed. A greedy algorithm as well as a smart...