Sharif Digital Repository

One of the most important challenges in drilling horizontal and directional wells is the optimization of hydraulics and hole cleaning and ECD management. In these wells, poor hole cleaning can lead to formation of cutting bed on the low side of the annulus and cause problems such as stuck pipe or increase in torque and drag. Also poor hydraulic design can lead to decrease in rate of penetration and thus, increase in costs. Mud weight should be placed inside the range of mud window (more than pore pressure and less than formation fracture pressure) in order to prevent kick of reservoir fluid or mud loss.In this thesis, the main goal is to optimize hydraulics and hole cleaning and manage ECD... 

During all operations in hydrocarbon reservoirs, there is a possibility of formation damage. These damages can reduce the production of fluids from reservoir. One of the major damages that can seriously affect the performance of a reservoir is the damage caused by drilling fluid. The main purpose of this research is to study the main mechanisms of formation damages when using oil-based drilling fluids and fixing or preventing these damages. Once the mechanisms are identified, it is tried to cure the damages but without acid-washing. The alternative method is surfactant-washing which is a surfactant-brine injection. This injection has been done for the first time. This study helps to industry... 

Service composition is an important problem in the cloud manufacturing paradigm in which, after receiving a customer request, combination of cloud services are determined for accomplishment of customer needs. Actually, customer need is decomposed to some distinct tasks such that each one is done by a company or a group of them. In this way, virtual and cloud-based production line can be developed based on requirements of customers. The ultimate goal of service composition is optimum assignment of tasks to factories while some objective functions (e.g. minimization of cost and time) and constraints (e.g. minimum reliability and availability) are considered. In this study, integer programming... 

The following research considers the problem of maximum graph orientation aiming to maximize the total weight of satisfied origin-destination pairs for which the capacity of each edge is limited taking into account the distance and cost. the origin of this problem can be traced to biology literature and protein-protein interaction networks. since the problem is a combinatorial optimization one, in addition to deploying exact methods using mathematical programming, heuristic methods are also investigated. addressing the problem, we propose a two-step procedure. in the first stage are detected the paths between origin-destination pairs and in the second one, the solution to the problem is... 

Communication growth in today’s world has affected every aspect of our lives. Transportation is an important part of our communication. Traveling, going from one place to another in a city or distribution of goods are examples of transportation. Transportation in which more than one vehicle is used from origin to destination is known as a multimodal transportation. This thesis is about a multimodal transportation problem for distribution of goods. Objective function is to minimize cost and there are constraints on the availability of the fleet. Also, it is possible in our model to use more cars with additional cost when the size of the fleet is not enough. The model is solved by optimization... 

In today’s modern world, there is an ever-increasing need for developing new ways to provide service in a health system in order to gain the satisfaction of the patients with economically effective methods. One of the challenges faced by a hospital is the allocation of the surgeries to the available surgeans. In this study, a mathematical model is proposed to schedule the operation rooms while considering the daily availability of the doctors, the expense of the operations, overtime hours, and post-operation care. The mathematical programming model is optimized as a stochastic model by using the approach of BIM.
An essential aspect of a hospital system design is the uncertainity of the... 

Supply chain management seeks to coordinate supply chain processes to achieve certain goals; one of which is minimizing the overall cost of the system. In this study integration of different supply chain management decisions i.e. location, routing and inventory management is considered in a single model. The products are distributed in a two-echelon distribution system. One type of product is shipped from a single factory to multiple retailers with deterministic demands through a set of distribution centers. The products can be stored in second and third levels facilities. The product is perishable with a certain shelf life. The product is delivered in a way to be consumed before spoilage. A... 

The application of composite systems has rapidly advanced in bridge and building construction. Shear connectors are the most basic parts of the composite systems.The connectors transfer the shear forces between the slab and the beam. They also prevent separation of the slab from the beam.
Therefore researchers have done widespread studies on the behavior of shear connectors and their load carrying capacity. Steel angles are one of the shear connectors that can be used incompositesystems. Only limited number ofstudies has investigated thebehavior of thistype of connector.
The purpose of this thesis is to investigate the behavior of angle shear connectors embedded in solid concrete... 

Shia theology has gone through different transformations throughout history. In the contemprorary age diverse studies have been carried out in order to discribe it’s preceding changes and future transformations. This tesis tends to show at first that “MacIntyre’s method of historical-philosophical study” is an overally justified model for such studeis, in comparison with the two other models of “Kuhn’s model of scientific revolutions” & “Lakatos’s research programs.” Afterwards, this model has been used for the study of shia theology and a brief narration of the rationality traditions of shia theology through the Iranian tradition has been given. The focus of this section has been on the... 

As today's world becomes more digital in every way, digital marketing has become a thriving industry, and digital marketing has become an important part of the world of digital business. Given the importance of this issue and the prominent role of startups in the today’s business world, in this project we discuss about digital marketing in start-ups business with a view to health sector using dynamic systems modeling. First, the effective variables are determined, then the relationships between them are determined and the model is designed. Finally, after analyzing the model factors and determining the extent and type of its impact on the main factors and variables, smooth the way to create... 

The Nurse Scheduling Problem (NSP), is one of the most complicated problem in health care management systems. The problem is to determine a work schedule by considering some requirements such as governmental policies, staff and their managers satisfaction, etc. Nowadays, while the demand of treatment centers for nurses has increased especially in hospitals, the population of qualified nurses has decreased. In such a fuzzy situation, the managers of the treatment centers want a better nurse scheduling in order to increase the quality of giving services to their patients and consequently increase their income. In this thesis, a two-stage nurse scheduling problem with uncertainties in... 

Characteristic of the reservoir, including the important discussion in the oil industry, is widely practiced in the modeling, simulation and EOR. One of the methods fordetermining the specifications of the reservoir is geostatistical technique. This means that a large number of realizations of the reservoir model to assess the uncertainty in reservoir descriptions of performance predictions should be made.However flow simulation of all these realizations is very difficult due to cost and time calculations.To mend the problem, we use ranking realization that finally a minor number of realizations are selected and flow simulation is used to them.In this project, we use streamline simulation to... 

For many low-powered portable and wireless electronic applications the finite energy density of chemical batteries places limits on their functional lifetime. Through the use of energy harvesting techniques, ambient vibration energy can be captured and converted into usable electricity in order to create self-powering systems which are not limited by finite battery energy. Typical energy harvesting systems are composed of two components, a transducer that converts the mechanical vibrations into electrical energy and a power converter that efficiently delivers the harvested energy to the electronic load. The practical design of energy harvesting systems must include both components and...