Sharif Digital Repository

Due to the suitable performance characteristics and the widespread use of Surface Piercing Propellers (SPPs) in high-speed crafts, many experiments and numerical studies have been conducted in this field. Due to the lack of a comprehensive series similar to conventional propellers in the field of SPPs, in this thesis, it has been tried to personalize the suitable basis by conducting two separate experimental tests in the National Iranian Maritime Laboratory (NIMALA) towing tank and the cavitation tunnel at Sharif University using computational fluid dynamics method and the commercial code STAR-CCM+. For this purpose, a wide range of phenomena and effective parameters on hydrodynamic... 

One of the common and efficient methods in the construction of large-scale structures from composites is the Vacuum Assisted Resin Transfer Molding (VARTM) method, which is widely used in the automotive industry, wind turbine blades, warships and pleasure boats, etc. VARTM is one of the liquid molding methods in which one side of the closed mold is replaced with a vacuum bag and the resin flows into the mold only with the help of air pressure (pressure of one atmosphere). One of the main challenges in the vacuum resin molding process is to be aware of the physics governing the flow motion in the porous mold so that the dry spots formed in the mold can be located accordingly. On the other... 

Metal and inter-metallic matrix composites offer high performance materials suitable for many low weight applications which are of growing interest in high tech industries. However, to submit their entire potential applications, their complex mechanical behavior has to be understood. Nevertheless, one of the major setbacks of designing with these materials has been the delamination phenomenon. So far, this phenomenon has been considered from macro-mechanical point of view regarding laminates to be semi-isotropic or orthotropic; which indicates the importance of micro-mechanical research to be done. Furthermore, the fact that macroscopic response and failure mechanisms of these composites are... 

Switching as one of important characteristics of on-chip network affects on power consumption and performance. In general there are two switching methods as circuit-switching and packet-switching. Hybrid switching includes both switching to have both resource utilization and scalability of packet switching and low power consumption and improved latency of circuit switching. Also topology is another network attribute that greatly affects the power, performance, cost, and design time/effort of NoCs. In this thesis, we propose a novel NoC architecture which holds both fixed connections between adjacent nodes and long connections virtually connecting non-adjacent nodes. Our proposed NoC... 

Membrane bioreactors (MBRs) which are commonly understood as the combination of membrane filtration and biological treatment using activated sludge have several advantages, but membrane fouling reduces the membrane efficiency, permeability and lifetime. An alternative is replacing a moving bed biofilm reactor (MBBR) with the activated sludge system which may reduce the effect of membrane fouling. The sludge produced in MBBRs has poor settling characteristics, therefore, their efficiency is limited by the sedimentation tank performance and they require a larger settling surface. The combination of moving bed biofilm reactors and membrane bioreactors can compensate for the drawbacks of both of... 

In this text to find the answer of the question “ what is it to be physical” in a definition form or a scheme of the term physical, firstly we sought for a possible consensus among recent physicists and philosophers. But from their answers not only we did not find any clear consensus but also most of them confess that the term is ambiguous and unclear. In a general aspect, we can categorize the answers to two theoretical and realistic perspective. The theoretical perspective, beside circularity and Hempel’s triviality, seems not to present any criteria for being physical. In realistic perspective, it seems that there is no ontologic constraint for being physical, that is from “being... 

The application of membranes for separate of particles in mainly microbial flacs , are fast growing in biological treatment systems. Membrane bioreactors are now considered as one of the major new processes in wastewater treatment. However , membranes are expensive and costly. This study is carried out to test an innovative , locally made filters for separation of flocs in an MBBR reactor. This innovative filter is replacing a traditional settling tank. This type of filters is made very cheaply and has important advantages in installing and operation. Experiments were carried out in a laboratory scale MBBR unit. A filter unit consisting of 3 innovative filter tubes were placed and the...