Sharif Digital Repository

The purpose of this research is compare some indicators of size, performance and productivity between exporter and non-exporter plants. For this purpose and, to answer questions of research we use from the industrial plants dataset (1382_1390). We obtain some stylized facts from the dataset then test evidence from data with econometric methods. In this dataset there are information about property, management, sales (domestic/foreign), inputs (domestic/foreign) and information about labor force, capital, investment of plant and many other variety information about plant. The results of my research show that always exporter in most measures of performance, size and productivity advantages... 

Using the data of the Tehran Stock Exchange, we analyze the characteristics and explanatory factors of major intra-group and out-of-group transactions and test the tunneling hypothesis in intra-group transactions. We find that out-of-group transactions can be largely explained by changes in control or management, firm size, and the type of the firm. However, intra-group transaction properties mostly depend on the difference between the parent company's cash flow rights in the buyer and seller companies. Also, in the final analysis, we conclude that many intra-group transactions are made to change the structure of the business groups, especially when investment companies buy shares of listed... 

Studies of the ownership structure of companies in different countries demonstrates that pyramidal ownership structures and business groups are present and even dominant in many countries. This type of structure allows the ultimate owners to leverage their capital and control more capital in the economy. Studies related to this type of ownership structure, scrutinize various motivations that have caused the formation of this type of ownership structure. Some studies emphasize the destructive role of business groups, such as tunneling and creating monopolies through common ownership in competing companies, and as a result, consumers and small shareholders are expropriated. Others, relying on... 

Nitrogen-Vacancy (NV) consists of a substitutional nitrogen located at a lattice site adjacent to a carbon vacancy. It has attracted much attention due to its application in solid state quantum information processing. Its long coherence time and ability to be used in ambient temperature made it a major candidate for quantum bit (Qbit). Due to its importance, a lot of theoretical studies for the NV’s properties based on the DFT and other single particle approaches have been done, while many-body approaches are not expanded so. For the first time, a generalized Hubbard Hamiltonian was used as a many-body approach to study NV defects. The obtained wavefunctions and states result to good... 

It is well known that sulfur removal from petroleum is necessary for both industrial and environmental reasons. Sulfur in petroleum products corrodes parts of internal combustion engines and refineries due to the formation of sulfur oxyacids and causes major air pollution and acid rain due to exhaust from diesel engines and emission of sulfur oxides. Hydrodesulfurization (HDS), biodesulfurization (BDS), extraction by ionic-liquids (ILs), selective adsorption, alkylation desulfurization and oxidative desulfurization (ODS) are some methods, can be effective in removal of sulfur compounds. Among these new processes, ODS appears to be particularly promising and is currently receiving increasing... 

Present study is to simulate laminar flow in a channel exposed to heat flux from the walls and filled with porous media by software ANSYS CFX in finite volume method. The analysis is based on the Naviere-Stokes equations in the flow field which are modified to Brinkman-Forchheimer equations to be applicable for porous media. Effect of Reynolds number and permeability on seepage velocity, temperature distribution, heat transfer and pressure drop are investigated.Simulations are performed for two cases: fully developed flow at the entrance of the porous media and developing flow, which are corresponding to the Reynolds numbers of Re=77.6 and Re=1553 respectively (U= 0.01 m/s and U= 0.2 m/s).... 

In this study, an integrated lab-on-a-chip (LOC) system was designed and developed to perform various processes, including cell separation, cell lysis, DNA extraction, and amplification, in an automated and unified manner. The system was designed to operate with fully disposable components, eliminating the risk of cross-contamination. The design includes five distinct microfluidic chips, each dedicated to a specific function. For cell separation, the inertial method was employed, which operates without the need for a micromixer and delivers high accuracy. Simulations demonstrated a recovery rate of 100% and a purity of 96.8%, while experimental results showed a recovery rate of 88.8% and a... 

Purification of hydrogen, as a clean source of energy has attracted great deal of attention in recent years. Among all available H2 separation methods, membrane technology has been known as the most appropriate way to produce hydrogen with high purity. In this study, we have tried to synthesis and evaluate the performance of perovskite ceramic membranes. The aim of preparing this type of membranes is to use them in separation processes in order to achieve H2 with high purity of >99%. First, general concepts about membranes are discussed. Then synthesis, recognition and performance evaluation of some perovskite membranes are presented. To prepare membranes, ceramic powders are synthesized by... 

Project Finance is a novel approach in financing big projects. High debt ratio, independency to promoter credit and establishing a special purpose company, are some of project finance characteristics that could be very beneficial in some projects. Liquid Natural Gas (LNG) is a solution for exporting natural gas to far destination. As economical and environmental benefits of using natural gas have been increased in recent years, LNG industry has been experienced rapid growth. In this project we analyze project finance and then describe economical motivation of using this method in LNG industry of Iran.

 

Cable-stayed bridges are the most economical solution for spans ranging from about 200 to 1000 meters. They have become more popular in recent decades due to their efficiency and appearance. The need to understand their seismic beahvior is apparent and any improvement can be useful. The main purpose of this study is to determine the effect of using three lateral cable arrangement groups namely, cross system, pulley system and spatial lateral cable system with two transversally inclined cable planes on seismic performance of cable-stayed bridges. In this research, the seismic consequences of these arrangements with interactions of key parameters like, the main span length and deck to pylon... 

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... 

The purpose of presented thesis, is modeling of the buried pipelines in soil slopes under dynamic loading using experiments on the physical model. Hence, numerical models based on five physical models, which are built and experimented on Sharif University of Technology’s shaking table device, have been analyzed using ABAQUS finite element software. In each model, several pipes are buried in slope, and the angle-wise placement of pipes differs with respect to slope slide. For the purposes of modeling, the experiment box has been modeled as rigid body. In order to model the soil behavior, Strain –dependent nonlinear elasticity, and mohr-coulomb criterion, has been employed. In addition,... 

Cardiovascular disease (CVD) currently remains a considerable challenge for clinical treatments. CVDs account for N17.5 million deaths per year and will predictably increase to 23.6 million by 2030. The main purpose is to create human model systems to study the effect of disease mutations or drug treatment on the heart. In addition, engineered cardiac tissues are considered promising candidates to be transplanted to improve the function of diseased hearts. For engineered active tissues/organs, 3D bioprinting can fabricate complex tissue architecture with a spatiotemporal distribution of bioactive substances (cells, growth factors, and others) to better guide tissue regeneration. However,... 

In recent decades, the earth is affected by climate change and the seasons has been warmer than the last. Furthermore, the efficiency of agricultural irrigation is low, and it leads to surface water drought and decrease in groundwater level. The Middle East is known for its warm desert climate. Lack of water resources is considered the most limiting factor for sustainable agriculture and water management of irrigation is a crucial issue for agriculture in Middle East. So it’s necessary to devote the cropping pattern considering above changes. The FAO56 Penman-Monteith equation is the standardized ETo equation. A comparison was made between 8 selected methods and FAO56-PM. Thus the method...