Sharif Digital Repository

An important step in the early stages of an oilfield development is the accurate identification of the location of production and injection wells which has a significant impact on productivity and profitability of the reservoir. Recently, operation companies in petroleum industry focus on production optimization, recovery enhancement and cost reduction; as a result, application of non-conventional wells (NCW) or non-vertical wells have dramatically increased. Well placement optimization is a complicated task as it is a function of several contributing factors including reservoir heterogeneities and economic constraints. The complexity of this task increases when it is considered as a... 

Iran is one of the biggest suppliers of oil in the world. Iran's economy highly depends on its oil. Iran has valuable old reservoirs that need some techniques to optimize their production of it.Determining optimal well placement and control is essential to maximizing production from an oil field. The reservoir optimization problem is an extraordinary complex problem that depends on many factors such as flow pattern, well specification, reservoir properties, and environmental and economic criteria. Finding the locations of injection and production wells and other optimum operational parameters in the oil industry are very important and have a great influence on the operation of the... 

In this thesis, the process of laser assisted machining (LAM) of metal matrix composites (MMC) is experimentally studied. The effects of process parameters (cutting speed, feed rate and depth of cut), laser parameters (laser power, laser frequency and laser beam angle), and the percentage of reinforcing particles on the tool wear and the surface roughness are investigated. Furthermore, the effects of these parameters on the built-up edge (BUE), chip shape, and workpiece temperature are explored.The experiments were performed using uncoated tungsten carbide and PCD tools under dry conditions. In order to analyze the sensitivity of the process parameters, the Plackett-Burman method was used... 

This research focuses on the robust mobile robot localization exploiting motion information acquired from an optical mouse operating based on optical flow technology. Most techniques of visual motion measurement are based on the well research discipline called “optical flow”. Theoretically, optical flow as a method of localization can be highly accurate, but it is sensitive to the noise and surface texture/optical characteristics and distance variations between the CCD detector and surface. As one could not achieve acceptable results in practical situations, to handle these problems, we propose to attach an acceleration – gyro (INS) sensor on the CCD detector (optical mouse) to improve the... 

Soft computing consists of a set of powerful methods that have been successfully applied to many different application domains, including business, engineering, and bioinformatics. In this research we propose an innovative approach that uses genetic algorithms to mine a set of behavior data output by a biological system in order to determine the kinetic parameters of the system. In our approach, the machine learning method is integrated with the framework of existent biological information in a wiring diagram so that its findings are expressed in a form of system dynamic behavior. An application of the method to the cell division cycle model has shown that the method can discover optimum... 

Determining the porosity, water saturation and permeability values in the reservoir rock, are major steps in the petroleum engineering and formation evaluation. Today in the oil industry, these parameters are obtained using Helium gas injection technique on core (Plug) samples. However, the coring operation is difficult and costly. In addition, there isn't the possibility of coring in some of wells, such as horizontal wells. In fact, the present research is the modelling of artificial neural networks to estimate permeability in one of the Iranian oil field reservoirs by using oil well logging data. In this research, MLP neural network has been used and for network training, the evolutionary... 

Concerns like fuel cost, pollution and global warming has made it necessary to look for new energy solutions. Renewable and alternative energies have proven themselves to be helpful in this matter. Renewable energy(RE) is the energy that comes from natural resources such as sunlight, wind, rain, tides, waves and geothermal heat, which are naturally replenished at a constant rate. Renewable energies are environmentally friendly, not cheap at the beginning but naturally available in a constant rate and wide spread, unlike fossil fuels that are localized in the limited places. In this thesis in order to generate environmental friendly power we consider two renewable energy resources: wind and... 

The purpose of this thesis is the optimal retrofitting of the moment resisting frames with telescopic dampers, using the adaptive approach. In this regard, numerical modeling of the telescopic behavior has been presented firstly. Also, a 3,9,20 story (sac) moment resisting frame has been modeled in the OpenSees environment and the time history analysis has been carried out under a specific earthquake record. It is shown that inter-story drifts of the frame exceed the acceptance criteria which has been assumed 2.5% according to the Life Safety limit. Then, the optimal retrofitting of the frame has been done. It is demonstrated that the maximum inter-story drift of all stories is 2.5% or less,... 

The objective of this research is to introduce a new comparative performance measure based on seismic fragility curve of structures. This measure is used here to investigate the efficiency of viscous dampers on the behavior of a weak mid-rise steel structure. Viscous dampers are commonly utilized to reach purposes such as decreasing the risk of the structure failure and restoration costs, weight reduction, and seismic rehabilitation of existing structures. These systems cannot be satisfactorily investigated using static loading concepts, and in order to achieve optimum design, conducting a nonlinear dynamic analysis is usually the most reliable procedure. Therefore, 5-span 12,15 and 18 story... 

Reducing energy consumption is one of the challenges facing wireless sensor networks with many solutions introduced for them with each having advantages and disadvantages. Some of the solutions introduced are based on using movable sinks. In this project, we attempt at proposing a place for the establishment of sinks using genetic algorithm that can reduce energy consumption in the net knots and increase the net life. This work should be done after reviewing the results of past researches and introduced methods. We will analyze the practicality of the proposed model using simulation and will show their advantages over the previous mentioned methods  

Due to the dynamic topology of vehicular ad hoc networks, routing of packets in these networks faces a lot of difficulties. The situation will become more challenging when we have to deal with Delay Tolerant Networks (DTN) which are also sparse and partitioned and we need to use some vehicles to store the packets and carry them from one partition to another. Despite all these difficulties, by looking through movements of vehicles in an urban environment, we can find out that the topology of the network does not change in a pure random way and we can bring the traffic models of streets into account for having better routing performance. In this thesis, we proposed an intelligent routing... 

Coverage rate is a critical criterion in all of communication networks. In this regard, there are many different methods for distribution of network particles duo to attain the most efficient region of coverage. This emerges from the limited ability of each networks particle both in range of communicate and power consumption. In this thesis an evolutionary method is introduced to how Wireless Sensor Networks (WSN) particles can be dispensed to have more reliable coverage rate. Using both static and mobile sensor packages to cover the desired area and used a cost function, coverage rate, the authors tried to maximize it to have an excellent performance of network. Then proposed algorithm is... 

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... 

Today competitive business environment has emerged manufacturers and suppliers to take into account specific requirements of customers and end users. Therefore, customers have more important roles in present contexts than what they already had. This significant change led into drastic alteration in the decision-making approaches involved in raw material supply, manufacturing processes, and final product delivery. One of the most influencing decisions in this regard is decoupling point determination in a supply chain. The key role of this point is due to the fact that this pint location affects almost all decisions being made in different stages of the chain. This thesis addresses factors... 

Safety assessment of the final disposal of radioactive waste is crucial to ensure the waste isolation from the biosphere for long periods of time. There are various scenarios for the radionuclide transport from the disposal site to the environment, among which the ground water scenario is considered as the main scenario of the radionuclides migration. In this scenario, the transport parameters of the radionuclides are very important in the safety assessment of the final disposal of radioactive wastes. These parameters are determined using either dynamic or static methods, which usually the dynamic method leads to more realistic results. In the dynamic method, one of the two approaches of... 

Prostate cancer is the second most common cancer in men and the fourth most common cancer in all cancers. Cancer treatment is done according to the type of cancer and its diagnosis stage with different treatment methods and plans. Brachytherapy is one of the most common methods of cancer treatment along with teletherapy, surgery and chemotherapy. In this method, the source of radiation is located near or inside the tumor, and its advantage is to achieve a lower dose ratio of healthy tissue to the tumor is lower compared to teletherapy. One of the challenges in brachytherapy is to prescribe the appropriate treatment plan for the patient, so that the maximum dose of sources reaches the... 

The increasing advancement of computed tomography (CT) systems has led to the recognition of this type of imaging as an accurate and reliable method in diagnosing and assessing damage to humans and materials. Adding dual energy imaging to these systems can increase the material's ability to differentiate in this system and provide higher contrast than usual. Recently, a medical imaging technique has been introduced that uses an X-ray tube and two detector layers on top of each other, each layer absorbing a different energy spectrum.dual layer computed tomography system has been introduced today as a suitable tool for evaluating and diagnosing many diseases, due to the reliability and... 

In recent decades, renewable energy resources (especially wind power as the fastest-growing energy source) have increasingly been employed for providing electrical energy all over the world given to the rising energy demands, reduction in non-renewable fossil fuels as well as severe restrictions applied to the utilization of these fuels because of their contribution in environmental pollution, generating greenhouse gas emissions, and consequently earth warming. The main factors in the development of wind energy systems to date are the easy access to this energy source in all seasons and its cost-effectiveness compared to other counterparts. One of the key components utilized for converting... 

The power generation system of this type of power plants operates on the air flowing through the power plant’s chimney and colliding with the turbine blades within the chimney. When the solar collector warms the nearby air and thus expands the air by absorbing the sunlight, a difference is created in the density. Then, this difference in the density creates the phenomenon of buoyancy, making the air pass to the top of the chimney through the collector.This study simulated and optimized a solar chimney power plant. The simulation and optimization were performed based on the information of Manzanares Solar Chimney Power Plant in Spain (located in 150 km from the south of Madrid). It was... 

One of the challenging issues in Iran's nuclear talks and Group 5+1 countries is the amount of Iran's enrichment capacity and the number of centrifuges needed to meet this demand. In this regard, Iran has recently announced that the basis for determining its enrichment capacity is the supply of fuel for the Bushehr power plant.Modeling and optimizing of gas centrifuge cascade is one of the most important problems in fuel cycle and isotope separation fields. To achieve this goal it is needed to comprehend of single centrifuge operation. Knowing the effectofsingle centrifuge parameters, it is easy to design a desired cascade. Minimizing the number of machines in the cascade is an anticipated...