Sharif Digital Repository

Crude oil production could cause the thermodynamic equilibrium of the crude oil to be disturbed in the well column which results in asphaltene precipitation and deposition. The thickness of the deposited material grows over time until it completely blocks the well column.Due to the hard and insoluble nature of deposited asphaltene, the two main chemical and mechanical methods are found to be more effective. It should be noted that the actual organic sediments in the piping are not pure and consist of three components: asphaltene, resin and paraffin. Therefore, it is very important to know the composition of the deposited material before selecting the appropriate chemical solvent.The samples... 

different phenomena occur between rotor and support rub impact causing system parts failure. Still Increasing the accuracy of manufacturing and decreasing the clearance of supports but the probability of rub impact between the rotor and support grows and this phenomenon is going to be more critical. This research would rub impact at two ends of four degrees of freedom Jeffcott rotor considering supports directional degree of freedom. Because the contact points are at two ends of the rotor, the rotational degree of freedom of the rotor is also considered. The system is modeled with 8-DOF and after numerical solving and comparison, the results with other papers, the system's behavior including... 

Dialysis which is an imperfect but most common treatment option for renal failure is divided into two main types:"peritoneal dialysis" and "hemodialysis". Peritoneal dialysis uses a fluid that is placed into the patient's stomach cavity through a special plastic tube to remove excess waste products and fluid from the body.Hemodialysis uses a special type of filter to remove excess waste products and water from the body and is divided to two groups :Clinical and Home.During hemodialysis, blood passes from the patient's body through a filter in the dialysis machine. In this Study first the basic aspect of renal failure and principle of dialysis process are described.Then information about... 

Due to largre number of patients treated by dialysis and its significant increasing progress, dialysis efficiency and patients' life quality are of great interest.Dialyzer, the dialysis beating heart, has the role of cleaning blood by removing toxic solutes and balancing volume of bood's water through hollow fiber membranes. In this thesis, firstly we tried to focus on performance characteristics of dialyzer by studying effective parameters influencing dialyzer efficiency and ultimately we set two important performance characteristics, ultrafiltration coefficient and solute clearance, as our goal parameters for evaluating dialyzer's yield. To this purpose, we designed an experimental set...