Sharif Digital Repository

Increasing the power of a turbocharged diesel engine without changing main engine components is important in industrial applications, with economic benefits. The engine power can be increased by higher boost pressure. In this research, the turbocharged diesel engine performance improvement was investigated to increase the engine power. As a case study, the performance improvement of OM355A turbocharged diesel engine carried out. For this purpose, the engine was modeled in boost module of the AVL software. First, naturally aspirated OM355 and turbocharged OM355A diesel engines were modeled. Then the simulation results were evaluated in compare with engine tests data. Maximum difference in... 

Hydrogels are three-dimensional polymeric networks capable of absorbing significant amounts of water. Recently, hydrogels based on acrylic monomers have garnered significant attention from researchers for the fabrication of motion sensors that monitor body movements, owing to their inherent ionic conductivity, remarkable flexibility, and biocompatibility. However, one of the common limitations of these hydrogels for practical applications is their inadequate mechanical properties. In this study, hydrophobic physical crosslinks formed from micelles of hydrophobic monomers and coordination-based physical crosslinks induced by trivalent iron ions (Fe³⁺), along with tannic acid (TA)-modified... 

Polyamides have found great attraction in the wide variety of application due to their desireable and tribological properties and appropriate processability. Due to their low mechanical strength reinforcing of these types of polymers has always been one of the important academic and industrial issues. In order to improve mechanical properties of such polymers, different kinds of reinforcement particles such as titaniom diaoxide, Nano clay, glass fibers (Short or long glass fiber), etc were used. Carbon nano tubes have high thermal and electrical conduction and mechanical properties; they are widely used as a reinforcement particle for polymer matrix. In this study, carbon nano tube and... 

Magnetic Resonance Imaging ,MRI, although as one of the most advanced medical imaging equipment is well known but compared to other medical imaging systems needs more time to imaging, so it has caused the patient dissatisfaction. According to the recently researches, filling the image data in a space of information that called ‘k-space’, in the process of image reconstruction, is the main reason of slow MRI. Image reconstruction methods for accelerating like half scan based on image reconstruction by using only a part of k-space is used in MRI systems today, but this method is associated with lower SNR image. Recent research on the theory of compressed sensing has been opened a new approach... 

A special steel beam-to-column connection, named Khor-jini, is commonly used for steel framing system in Iran. In this system, two continuous beams are passed next to the columns and are connected to the column side using seated brackets.This type of connection has been common in Iran from the late past. Unfortunately, the seismic behavior of Khorjini frames had not been sufficiently studied prior to Manjil Earthquake of 1990. Due to very large damages which occurred in steel structures especially in connections during the said earthquake, the seismic behavior of this type of connection was studied and some of its weak points were recognized.In this study non-linear... 

Cloud computing is a way to increase capacity or add capabilities dynamically without investing in new infrastructure. The purpose of this project is the use of specialized algorithms for efficient energy management for cloud computing environments.One of the issues that is very important with respect to cloud computing is considering lifetime of servers or physical machines. Servers are some of the most important and critical elements of cloud computing. Server costseffect on the costs of the entire cloud computing system and the interference of serverseffects on entire system. Lifetime of each sever is dependent on a few factors, the most important of which is the number of switching... 

In the present research, model-based reasoning is introduced and explained based on Giere’s explanation of model. In other word, this research could be regarded as a reconstruction of model in Giere’s books and papers due to prpose a clear explanation of model-based reasoning. In the second chapter, after the introduction, the concept of model in Giere’s distinguished book, “Explainnig Science: A Cognitive Approach” (1988) is introduced and analyzed. In the second chapter, however, the concept of model in Giere’s recent works is traced. “An agent-based account of model” and “focusing on functionality rather than ontology” could be explained as the two important differences between his...