Sharif Digital Repository

With high power conversion efficiency, comparable to silicon solar cells, the conventional perovskite solar cells (PSCs) are leading the photovoltaic research scene. However, they have poor stability in operation due to instability of organic-inorganic hybrid PSCs. Several methods have been proposed to improve their stability including Substitution of the organic component by an inorganic one For example, inorganic perovskite compound such as 〖 CsPbI〗_3 with bandgap about 1.7 eV is a good candidate. However, it requires high synthesis temperature (about 300 ℃), and the resulting cell has a lower efficiency than the organic one. Introduction of Cs, as an inorganic element, into organic... 

With the rapid proliferation of residential rooftop photovoltaic (PV) systems, current and voltage unbalance issues have become a matter of great concern in low voltage (LV) distribution feeders. This, however, necessitates identification of the hosting phase of the connected single-phase customers and PV panels. Both of the challenges have been addressed in this thesis. In the first place, this thesis proposes a mixed integer linear programming (MILP) model for phase identification problem. The model considers potential error in the input data provided by smart meters. To mitigate negative impacts of the error, the data associated with several consecutive time intervals are taken into... 

One of Iran’s most important priorities at present is the development of the human resources and one of the most important skills of this human resource is decision making and problem solving. During the past few years, there have been numerous criticisms about the educational system in Iran without a substantial solution being offered to replace the existing approach. Aseman Group has been trying to promote system thinking in children. In Aseman, they believe that system thinking is one probable solution in order to develop thinking, decision making and problem solving skills in our human resource at early age. However, one of the many problems facing this group, is the resistance shown by... 

In tis study, 4 approaches were applied for estimating Minimum Miscibility Pressure (MMP). An oil sample from Norooz and Soroosh field has examined by means of association gas of foroozan field and Carbon Dioxide gas in experimental approach.the experimental method used for estimating MMP in Slim-tube. This kind method is applied in industry widely. The results indicate that the MMP of Carbon Dioxide and Norooz field oil is 3538 psi and with Soroosh field oil is 3650psi. the MMP of foroozan associated gas and Norooz field oil is 5643 psi and MMp with this gas and soroosh field oil not estimating  

Mixed matrix membranes (MMMs) are new generation of membranes which possess simple processability of polymeric membranes and high separation ability of zeolitic membranes. The present study, concentrates on the fabrication of MMM for CO2/CH4 separation in a combined method as encompasses not only higher permeability but also superior selectivity in comparison with conventional polymeric membranes. The most appropriate technique for MMM making, is the process which provides participation of distributed zeolite particles in separation efficiently while the polymeric matrix acts just like a particle support and dose not play an effective role in separation. Investigations demonstrates that... 

In this research incorporation of SAPO-34 zeolite filler into polycarbonate membrane was investigated for fabrication of mixed matrix membrane (MMM). The main purpose of addition of zeolite in polymer matrix is to enhance the separation properties of pure membrane by means of the selective pores of SAPO-34. SAPO-34 possesses pores with proper size for separation of CO2 from CH4 by molecular sieving mechanism. Pure polycarbonate membrane and PC/SAPO-34 MMM was prepared by solvent evaporation method using dichloromethane as solvent. Zeolite loading was varied between 5-30%wt. First of all, polycarbonate was characterized by DSC, FTIR and viscometer analysis in order to determine all the... 

“How can we generate a random point with uniform distribution over a convex body ?” According to it’s applications, it’s important for a solution to this problem to be applicable in high dimensions. Here, we are interested in algorithms with polynomial order with respect to the dimension. All existing methods for dealing with this problem are based on the Markov chain Monte Carlo method, i.e. a random walk is constructed in such that its stationary distribution is the uniform distribution over. Then, after simulating “enough” steps of this random walk, the distribution of the resulting point is “approximately” uniform. The real problem in Monte Carlo method is analyzing its “mixing time”,... 

Ruthenium based-oxide coatings on Titanium anodes are widely used as DSA (Dimensionally Stable Anode) for chlorine and chlorate production. Coatings consisting of composition of highly conductive oxide of noble metals (Ru, Ir and Pt) make them as long lasting anodes in chlor-alkali technology.In this work, a newly anode by a ternary coating of IrO2, RuO2, and TiO2 on the Pt-coated Ti was developed through thermal decomposition of iridium and titanium and ruthenium inorganic salts dissolved in n-pentane. The effect of deposition parameters such as current density, time, different condition of baking, heating, mole ratio and pulling up the samples was investigated to find out reasonable... 

A hierarchical production system in make-to-order environment is presented in this thesis. This production system is consisted of three different decision making levels. Maximum acceptance for production within customer specified time interval was done in the first stage, which is called order arriving stage, based on different client criteria, type of demanded product, and production system constraints. A new hierarchical decision making structure for accepting or rejecting arriving orders is proposed in this level. The output of this acceptance level is orders having maximum production system defined criteria, and minimum production cost along with order delivery time with minimum delay is... 

Cancer is one of the leading causes of death in the world accounting for 7.6 million deaths (around 13% of all deaths) in 2008. Deaths from cancer worldwide are projected to continue rising, with an estimated 13.1 million deaths in 2030 according to WHO. Cancer is a disease caused by normal cells changing so that they grow in an uncontrolled way. There are over 200 different types of cancer because there are over 200 different types of body cells. Various types of treatments are available among them surgery, radiotherapy and chemotherapy are the three major ones. Mathematical models and control theories can be employed to improve the quality of treatment and obtain systematic strategies of... 

Incineration of oil wastes is a very important subject in oil refinery Industries. Such wastes may include toxic ports such as CO or hydrocarbon compounds, in either liquid or gas forms. In this project, we simulate an oil refinery incinerator. The industry has decided to increase the waste capacity to 150% of its design conditions. This causes the appearance of CO and methane at the outlet of incinerator stack. We investigated the incinerator operation and-found that we might solve the pollution problem by re-design of air and waste inlets to the incinerator. In this regard, we first simulated the incinerator in its normal operation to validate our numerical modeling. Next, we assumed... 

In this thesis, a numerical analysis of micro chamber filling in centrifugal microfluidics is investigated. In the development of micro total analysis systems, it is often necessary to achieve complete and uniform filling of relatively large micro chambers. With centrifugal devices, these large micro chambers must often be orientated perpendicularly to the direction of centrifugal force and are usually bounded by materials with varying surface properties. On the other hand, the mixing characterization of two fluid by centrifugal microfluidic method has been also conducted. The multiphase flow analyses based on Eulerian-Eulerian approach have been conducted and the VOF method was used for ... 

Recycled materials have been very much taken into consideration in recent years due to economic issues and the preservation of natural resources. Warm Mix Asphalt (WMA) is also of particular importance due to less energy use in construction and environmental compatibility. This study examines the compressive workability and resistance to low temperature crackings of warm mixt asphalt containing reclaimed asphalt pavement (up to 30% by weight of aggregate). Sasobit was used as an organic additive in 1.5% by weight of bitumen in warm mix asphalt. Two additives of crumb rubber modifiers (9, 15 and 18% by weight of bitumen) and hydrated lime (1.5 and 2% by weight of aggregate) were also used to... 

Urmia Lake is a strong electrolyte containing various salts, with a thermodynamic identity. Changes in the temperature and volume of lake water cause a change in the concentration of ions in this brine as well as the composition and precipitation of salts in the lake. As a result of these changes, the thermodynamic properties of brine are also changed. The purpose of this study was to investigate the effect of mixing the rivers entering the lake and calculate and analyze the changes in the quality and hydrogeochemical characteristics of Urmia Lake and the amount of precipitation and dissolution of the main minerals in Urmia Lake during the period of 2007-2013 per month. For this purpose,... 

The main objective of this study is a numerical simulation of flow and mixing behavior of two miscible liquids in a new static mixer over the Reynolds number in the range of 20-160. The performance of the proposed static mixer has been compared with the well-known three different static mixers namely, Kenics, SMX, and Komax. Pressure drop ratio (Z-factor), a coefficient of variation (CoV) and extensional efficiency (α) characteristics were, respectively, used to evaluate power consumption, distributive mixing and dispersive mixing performances in all static mixers. Since there are no experimental data for examined mixers, firstly, the CFD model was validated with measured data of the... 

One of the most common methods of coating gold on the surface of a metal is electrodeposition which is performed in cyanide and non-cyanide solutions. In recent years, gold cyanide baths have been replaced by Non-cyanide baths because cyanide baths are not suitable due to their very toxic properties despite good coating quality. In this project, the coating was performed through electrodeposition process in two non-cyanide gold baths including sulfite bath and mixed sulfite-thiosulfate bath. The results have shown that the stability of the sulfite bath is about 15 days, but the mixed sulfite-thiosulfate bath has a relatively high stability with 165 days, comparable to the cyanide bath. The... 

Various factors, such as increasing or decreasing the heat removal from the initial circuit, or increasing the flow rate of the cooling fluid in the reactor, causes the phenomenon of the coolant mixing in the PWR reactors. In this project, the thermohydraulic test of coolant mixing has been simulated in the pressure vessel of the Bushehr nuclear reactor. In this test, the mixing of the coolant caused by the reduction of heat removal from the primary circuit by the secondary circuit is investigated. In this case, the primary circuit temperature increases in the loop where the heat removal is reduced. The most important consequence of this event is the reactivity changes at the core of the... 

In the limit case of incompressibility, the displacement-based finite element methods are not capable of finding the solutions with adequate accuracy. Moreover, discontinuities in displacement field or strain field which exist in the interior of the elements should be dealt with appropriately. The u/p mixed formulation provides a suitable context for modeling the incompressible problems. It is capable of solving general problems in which there exist geometrical or material nonlinearities. In the case of employing the eXtended Finite Element Method (XFEM), uniform meshes can be used for problems with discontinuities and in fact the discontinuities can be decoupled from the mesh. In this... 

By virtue of a robust and efficient method, the solution of triple and quadruple integral equations which are the keys of various mixed boundary value problems corresponding to half-space and full-space media is addressed. These multiple integral equations are reduced to a well-known Fredholm integral equation of the second kind. In order to write the governing integral equations of the problem, Green’s functions play an important role. Therefore, Green’s functions of homogeneous and non-homogeneous transversely isotropic media in the form of line integrals including Bessel functions are obtained. Three interesting mixed boundary value problems in transversely isotropic materials are...