Sharif Digital Repository

Cardiovascular disease is responsible for a majority of health problem in developing countries. Heart diseases are the leading cause of death in the United State with approximately 40% of the death occurs by heart failures and coronary artery defects. Myocardial infarction is one of the diseases that occurs by coronay artery blockage. Cardiac tissue engineering (CTE) is an emerging field that holds great promise towards the development of innovative treatment strategies for heart disease. There are two common scaffolds for CTE, electrospun fiber mats and hydrogels. Although fibers are known as 3D environment for cells, they actually act as a 2D surface, because of lack of cell infilteration.... 

In this thesis, the notion of nowhere-zero flow on graphs in defined with values is an Abelian group. It is shown that the existence of nowhere-zero flow with values in H depends on only the cardinal of H. Also the existence of nowhere-zero flowwith values on Zk is equivalent to the existence of the nowhere-zero flow with values in the set 1,2,...,k-1 on group Z.It is a easily seen that the nowhere zero flow on the graph with bridge doesn’t exist. Also has been proved any graph with no bridge has nowhere-zero 6 flow.Concidentally, the existence of nowhere-zero 5 flow for graphs with no bridge isstill an open problem.In 3-flow case, recently it is shown that any 8-edge connected graph has... 

Studying the behavior of materials at high strain rate is necessary for design and analysis of structures subjected to impact loading. Therefore, design and construction of apparatuses that enable us for testing various materials under impact loading is very important. The split Hopkinson pressure bar test -one of the most important impact tests- is utilized for dynamic loading at constant strain rates ranging from 100 to 10000 1/s.
In this thesis, first we explain about the behavior of materials at high strain rates and then focus on the behavior of polymers -that are widely used in different industries- under impact loading. Also, basic concepts of polymeric Hopkinson pressure bar and... 

Spirocycles have been employed both as core structures and appended to the periphery of molecules in drug discovery. The major advantage that spirocycles offer as core structures is their inherent three-dimensional nature and concomitant ability to project functionality in all three dimensions. Spirocycles have been employed both as core structures and appended to the periphery of molecules in drug discovery. The major advantage that spiro cyclesoffer as core structures is their inherent three-dimensional nature and concomitant ability to project functionality in all three dimensions. However, to take full advantage of spirocycles, the ability to control stereochemistry at multiple positions... 

The concurrent flow of oil and water is a common occurrence in the field of multiphase flow in different fields including petroleum industry. In oil and gas, production engineers often face a situation in which more than one phase is flowing through the producers. In such conditions an accurate assessment of pressure loss inside the well plays a vital role in efficient and effective production planning. Changes in well orientation, wellbore diameter, reservoir and fluid properties as well as fluid flow rates are among parameters in which will affect the flow patterns that can occur inside a well during its life time. These flow patterns are created as a result of a competition between... 

Casing design is one of the most expensive parts in the drilling of oil wells, and any cost reduction with the basic design of these casing strings will significantly reduce the total cost of the operation. In recent years, occurring scenarios-based casing design has become popular; Because in many cases, it eliminates non-occurring scenarios such as gas kick and saves on drilling costs. In this study, we have tried to investigate all scenarios that may occur during the lifetime of the well, whether drilling or production, and for each well, based on its own field information, possible scenarios for each casing part are selected separately and the applying loads are calculated. For this... 

This thesis presents the results of an experimental and analytical study on the application of the strapping technique for seismic retrofit of reinforced concrete columns. In this technique, the columns are externally confined by post-tensioned metal strips. In the first phase of the experiments, the compressive stress-strain behavior of strapped cylindrical and prismatic specimens was studied. Effects of several parameters were studied including shape and size of specimens, strength of plain concrete, mechanical characteristics of confining strips and the level of pre-tensioning of the strips. The second phase of the tests included studying the lateral performance of strapped RC columns.... 

In order to reduce structural and nonstructural damages and associated financial losses during intense seismic events such as Bam earthquake, seismic retrofitting of existing structures should be considered as a special issue. In this regard, for quantifying the seismic performance of structures a guideline termed “instruction for seismic rehabilitation of existing building No.360” is issued which is mainly borrowed from performance-based assessment procedures FEMA 356. In contrast to conventional seismic design methods which are based on controlling stress ratio for different load combinations, in performance-based earthquake engineering methodology, the displacement control of structural... 

Considering the role of fluid storage tanks within or after an earthquake and the irreparable damages from their destruction that arise from the nature of the fluids of flammable or toxic nature stored in those tanks, it is very important to ensure stability and durability of the tanks when an earthquake is occurring. One of the most important damages to storage tanks within the past earthquakes has been lack of stability of their walls taking place in the form of elephant buckling. A certain storage tank was subject to a case study in this research and the tank's body, foundation, anchorages, the tread between the fluid and tank's body and between the bottom sheet and foundation were... 

Masonry buildings are wide spread in Iran and some other countries . These buildings are highly vulnerable to seismic excitations if not constructed in accordance with engineering fundamentals . Thus it is necessary to retrofit these structures to flee from humanitarian and economical damages inflicted by earthquakes. One of the critical vulnerabilities of masonry buildings is due to transverse instability of it’s infills . Therefore to study out of plane behavior of these elements , an infilled frame is modeled and analyzed with ABAQUS , the results of which is in good congruence with the experimental one . In this model , stress distribution due to one way arching action in the confined... 

It is more than a century to study qualitative and quantitative behavior of structures against earthquakes will be benefited from laboratory studies. In fact, the best method for observing the behavior of a structure during an earthquake is earthquake simulation on the structure. Today, the most effective way to do these tests is simulating of earthquake by using of Shaking Table. The shaking table consists of three main parts: electronic, hydraulic and mechanical. The accuracy of earthquake simulation’s results are very important. In recent years, numerous studies on the dynamic behavior of the above components and the interactions between these components are performed. In this study, we... 

Fused pyrimidines have attracted considerable attention recently in synthetic organic chemistry because of their wide range of biological activities pharmaceutical, therapeutic properties, antibacterial, antiviral, antitumor, and anti-inflammatory activities. We have reported a new and efficient synthesis of dihydro and tetrahydro pyrimidines fused to 2H-chromen-2-oneand cyclohex-2-enone and pyrimidine fused to uracil via two component reaction of 4-amino-2H-chromen-2-one, 3-aminocyclohex-2-enone and6-aminouracilto 1-aryl-N,N'-bis(arylmethylene)methanediaminein the present of iodine as catalyst.Molecular iodine has received considerable attention in the last few years due to inexpensive,... 

The observed response of medium rise buildings during sever earthquakes worldwide has indicated that RC buildings with shear walls behave considerably better than other buildings. The conviction that shear walls are inherently brittle still prevails amongst engineers, and therefore, they usually prefer to choose moment resisting RC frames without shear walls. In this study, a number of RC frames, with and without shear walls are designed in accordance with the seismic codes, and are then subjected to an assemble of severe earthquakes. The results of timehistory nonlinear analyses of these models are then used to investigate the effect of the presence of shear walls within the framework of... 

The paper presents the results nonlinear analysis of steel base plates subjected to different combinations of axial and bending forces. The bending forces range from small moments representing small eccentricities to large moments from seismic actions. The results of analyses proved to be in good agreement with experiments. The parameters investigated in this study are as follows: distribution of strain and stresses in the concrete foundation and the steel plate, the strains and stresses in the tensile anchorage bolts, the location of neutral curve under the base plate, the centre of compressional reaction forces in concrete, the flextural rigidity of the base plate connection, and the axial... 

By investigating reports of severe and destructive earthquakes of the past years we have realized that shear-wall structures most of the times had better seismic performance and more reliability than moment resistance frames. Asymmetrical arrangement of shear walls due to architectural limitations caused distortions in the structure. On the other hand, seismic regulation don’t compliance existence of twisting moment in the structures. What was said are all the most important reasons for not employing asymmetric shear wall sets in the structures by designers. The purpose of this study is to compare the seismic behavior of symmetric moment frame structures with seismic behavior of symmetric... 

Using shear walls as an earthquake resistant system in reinforced concrete structures enjoys prominent position among civil engineers in recent years. As most produced stress and damage occurs at the edges of shear wall under combination of vertical and lateral loads, it is expected that seismic behavior of shear walls can be improved by using boundary element at their edges and considering special reinforcing rules. In this thesis, the effect of boundary element details and parameters on seismic behavior of shear walls has been evaluated by a finite element model. By comparing the results with parameters specified in codes, the modeling parameters and performance levels given for shear...