Sharif Digital Repository

One of the main issues concerning the irregular building structures is the determination of the critical directions of earthquake input to them that leads to maximum structural response parameters. In applying the seismic excitations to the structures, there is always a critical direction in which the application of seismic loads in those directions, would cause the structural system to experience its maximum responses. Therefore, considering the probability of positioning of the structure’s principal axes in that critical direction, the structure needs to be designed based on the critical seismic induced demands. In this project, the CQC3 method has been used to determine the critical... 

Up to now, many seismic design methods and construction technologies have been investigated to reduce the seismic responses of bridges, buildings and potentially vulnerable structures. [1] Introducing a new effective systems aim to control of vibration caused by earthquake on the structures will be useful. This system is based on repelling of imposed force to the structures with tuned mass dampers (TMDs), to gain minimum damage. The detuning of the structures by equipped with TMDs resulted from nonlinear behavior due to dynamic loads such as strong ground motions are real concern in the practical applications. The application of TMDs, as expected, can reduce the deformation of the... 

Till today types of demand response program have been identified as one of the most effective and usefull programs in order to the energy efficient consumption and followed by, improving the network's reliability. Also some of these plans have reduced the risk of the retailers and as much as possible prevent the likely loss of these companies at the high energy tariffs times. The required for doing some of these types of plans is investing on various parts like infrastructure mutual relationships between retailers and customer and also smart meters which will require valuation. Till now so many various ways have been done for valuation on types of demand response program plans. This thesis... 

Modern physics and the standard metaphysical point of view, together, result a contradiction which we will explore its roots in this thesis. Be- sides, focusing on various identifications of individuality and the prin- ciple of identity of indiscernibles will made us to choose between to metaphysical and equal pockets, Particles as individuals and particles as non-individuals.Physics alone could not help to choose between these too pockets. Therefore, we will face a metaphysical under-etermination which we have to break in order to save our realistic ontological com-mitments. By a breif study among the possible ways for breaking that underdetermination, structural realism will be the most... 

Ultrasound hyperthermia is a commonly used noninvasive approach to destroy cancer tumors. High Intensity Focused Ultrasound (HIFU) is a technique based on hyperthermia. It creates short and local elevations of temperature at a focus site within the tissue of interest. The main goal of HIFU is to maintain the temperature between 50 and 100 °C for a few seconds (typically less than 10 s), in order to cause tissue necrosis. In order to predict the effects of hyperthermia, accurate and effective modeling is needed. This study considers a 3D simulation of the hyperthermia based on HIFU method in the liver tissue. Temperature distribution and lesion volume changes, with a temperature of above... 

Using magnetic torquers as the sole actuator for attitude control of small satellite despite its benefits has a drawback that is lack of controllability. Mechanical torques can be created only perpendicular to the instantaneous magnetic field vector, thus at each time instant the satellite can be controlled only around two axes out of its three perpendicular axes.
Fortunately because of the satellite motion, the direction of uncontrollable axis changes by time, therefore the sufficient attitude control can be achieved along time. Almost all of the present magnetic attitude control methods need more than one orbital period to control and cause the attitude to converge to the desired... 

Structural defects such as cracks may be produced in structures and machineries under fatigue load operating conditions. The presence of crack can lead to catastrophic failures in certain conditions. The occurrence of cracks affects the dynamic and vibration behavior of the structure considerably. These vibrations can be used for identifying the cracks and appropriate actions can be taken to prevent more damage to the system. Therefore, in this thesis vibration analysis of a Timoshenko beam with a vertical and horizontal crack has been considered. A continuous model for vibration analysis of a beam with an open edge crack including the effects of shear deformation and rotary inertia has been... 

Computer-assisted language learning (CALL) has been the focus of investigation in the field of foreign language learning for many years. This study aimed to investigate the impact of learning through blogging on the students’ essay writing skill and attitude in the Iranian context. As an extension of the research conducted earlier by Lin (2015) 32 Sharif University of Technology students were selected as the participants of the study. To this end, the students were divided into two groups of experimental group and control group. Then, they were instructed in two different ways by using different teaching methodologies. The bloggers, experimental group students, did not receive any direct... 

Understanding many issues related to environmental geotechnics and soil sciences such as: instability and collapse of soil slopes, sinkholes, leakage from landfills and isolation of nuclear landfills, and optimization Agricultural processing depends on our knowledge of the behavior of unsaturated soils and their volume changes. To better understand the behavior of unsaturated soils, it is important to study the soil-water retention curve (SWRC) and the factors affecting it. These include factors such as porosity, grain size distribution, soil minerals, pore size distribution, and pore water chemistry, which affect soil-water retention curves and volume changes. Since the simultaneous effect... 

The purposeof this study isto findthe propertiesof an equivalent linear Multiple Degrees of Freedom (MDOF) system, or so-called substitute structure, that its response is an approximation ofthe target actualnonlinearMDOF structure’s response (Shodja, 2013). In that regard,thestiffness anddampingmatricesofthe substitutestructure are considered as functions ofthe stiffnessand dampingmatrices ofthe actualnonlinear structure. Inthisway,the substitute structurescan be constructedthroughtrial and errorfor structures with different fundamentalperiods, damping ratios and number of floors.Inthat regard, a number of multi-story steel moment resisting frames are considered. The ductilities of these... 

In this study, seismic performance of steel diagrid structures is investigated using far-field earthquake records and their seismic performance factors, such as overstrength factor (Ω_0), ductility ratio (µ_T) and response modification coefficient (R) are evaluated according to the FEMA P695. To meet this objective, 12 archetype 3-D models of diagrid structure with two different height of 8 and 12 stories and three different diagonal angles of 45, 63.4 and 71.5 degrees are designed according to the ASCE 7-10 and using response modification factor R=3.6. With regard to the main horizontal beam connections with the diagrid system, equal number of models with pin and rigid type of connections...