Sharif Digital Repository

To investigate the accurate performance of a structure, the knowledge of the way its connections function, is of great importance. Moreover, cognition of the actual behavior of connections which is often semi-rigid can lead to better apprehension of the actual and more accurate behavior of structures, whilst it is often considered to be pinned or fully-rigid.Therefore, in this study a new semi-rigid steel connection of beam to column will be introduced, and its behavior will be investigated using commercial finite element packages along with mathematical approximate modeling methods. One of the features of this connection is that its behavior mainly depends uponfolding of top and bottom... 

The synthesis and usage of TiO2/ZnO nanocomposite thin film in antibacterial activity against E-coli were experimented through a systematic research. TiO2/ZnO nanocomposite films can demonstrate different properties like gas sensing, self cleaning and treatment of the broad range of aqueous pollutants when it is exposed to light with wavelengths less than 400 nm. This phenomenon happens because of the photocatalytic reactions in the nanocomposite thin film which cause active species production on the surface of the thin film. The nanocomposite synthesis was based on sol-gel process in atmospheric pressure. In this study titanium dioxide is prepared by sol gel method from titanium... 

Low back pains (LBP) are prevalent and costly. One of the important factors causing LBP is excessive axial compression and shear forces that are applied on the intervertebral discs during different activities. Due to lack of direct in vivo measurement methods for estimating these loads, musculoskeletal biomechanical models have been emerged as indispensable tools under various activities. Different biomechanical models have been suggested to estimate muscle forces and spinal loads base on optimization, EMG and hybrid (EMG assisted optimization, EMGAO) methods. Although there have been a number of studies on the differences between various optimization and EMG-based methods, there has been no... 

Infectious diseases have always been a threat to mankind, and is the greatest causes of death of children and young people. Although this type of diseases is a serious threat to public health; the allocated resources in responding to a semi-large pandemic is inadequate. Therefore, it is important to spend the resources in the most effective and efficient ways to improve pandemic response capability. That is why considerable research be devoted to study different aspects of epidemics, and developed mathematical approaches to choose appropriate strategies in pandemic response. Since the epidemic models are simplified means to describe the transmission of disease, researchers often use these... 

Lifetime extension would be a necessary preventive action to halt micro cracks expansion on the airplane external surface. To decide about whether to perform this operation, one should examine technological maturity, costs and technical parameters. Technical status in lifetime extension is one of the major drivers of this decision which should be considered in the first step of technology management process which is known as the technology attractiveness step. In this research, major technologies of rejuvenation is examined and categorized by the technology mapping. Also, key processes of rejuvenation and technological fields ranking has been determined by the procedural view tools of the... 

Torque variations caused by intermittent combustion and inertia effects of reciprocating components, exert significant torsional excitation on crankshaft of internal combustion engines. These excitation induces considerable torsional vibration on crankshafts. Therefore, modeling and analysis of crankshaft torsional vibration and absorber systems, especially in automobiles engine that crankshaft tolerate high amplitude excitations coupled with heavy inertia effects has high importance. In this study, ability of centrifugal pendulum vibration absorber and dual mass flywheel which used in rotating machinery for vibration reduction, will be examined. At first, cranktrain will be torsionaly... 

Because of importance of knowing angular velocity in a lot of engineering problems, Rate gyroscopes is widely used in different engineering fields. Among all kinds of gyroscopes, proof mems MEMS gyroscopes are mostly used because of their low cost and light weight. Improvement of the accuracy of the MEMS gyroscopes and their based inertial navigation systems is intended in this thesis considering some undesirable conditions on the gyro and trying to solve the gyro’s equations in that conditions. Existing linear or angular acceleration on the structure that the gyro is installed on is one of these undesirable conditions; Quadrature error in the gyroscope is the other one. In this thesis, the... 

Marine current power has been utilized in recent years as one of the most foreseeable renewable energy sources. In this study a multi-objective hydrofoil optimal design is carried out for use in marine current turbine in order to improve hydrodynamic performance due to low speed current in Qeshm channel. A particle swarm optimization code using FORTRAN is developed and coupled with XFoil software as flow solver that is based on panel method. B-spline curve is used to parameterize the hydrofoil shape and the coordinates values of the control points are designated to act as optimization parameters. Validity of flow solver examined by comparison made between computed data against experimental...