Sharif Digital Repository

Today, many evidences, including the distribution of galactic velocities, gravitational lensing observations, and the cosmic microwave background, show that there exist dark matter (non-baryon matter) in large-scale cosmological structures that are stable, free of charge and without color, which has gravitational interaction like normal matter. The hypothesis that weakly interacting massive particles (WIMPs) as a dark matter candidate with mass range of several tens of GeV to several teV and with the typical couplings of Electroweak order of magnitude, is an attractive and desirable model, Which naturally explains the density of cosmic dark matter in agreement with observations. Alongside... 

Vapor in agro-industry hakim farabi production electricity, Turbines force and thermal energy for Yellow and white sugar in sugar production. In the utilization to supply water for the boiler , condensate water return use Until plant be able to do its work ¬good quality of condensate water decrease cost of destruction energy in blow down and can save energy, reduce cost of chemical operation for optimum boiler water and costs associated with wastewater treatment. unclean condensate water consist of sugar and Electrical conductivity more than permissive is not suitable for use in The boiler because Increase the total dissolved solids and decreasing pH lower than the Extent permitted. The... 

The Rotary Combustion Engines are known as Wankel Engines, for the first time designed and built by German inventor, Felix Wankel. In open letrecher, research reports about these engines are much less than piston engines. While, the wankel engine hase many advantages such as lower volume, less weight, less vibration and use of fuels lower octane number in compared with reciprocating engines. Therefore, it has particular importance in industries such as aircraft manufactueres.In this theses after the introduction chapter, Wankel engines and Turbochargers usage are reviewed. Then the Wankel engine and its turbocharging are searched in letrecher. Then, a computer code for simulation the Wankel... 

Nowadays internal combustion engines play an important role in the power generation as well as transportation fields all over the world. By using the turbocharger in internal combustion engine, more power is obtained in compare with aspirated engine having the same size, which is limited for gasoline engines. In this research, by a three-zone computer simulation code and experimental tests, the power boost limitations of the gasoline turbocharged engine are investigated. The results of single cylinder aspirated gasoline engine tests are used for validation the natural aspirated part of the code. For validating the turbocharged engine simulation, the results of a four cylinders gasoline... 

Lately, a wide application of eco-friendly polysaccharide-based hydrogels in waste water treatment has received enormous attention in the literature. The effluents containing dye materials from the processing industries are washed off into rivers and lakes which can be very harmful to creatures. Low-cost biopolymers and biodegradable adsorbents have been researched to be a good tool to minimize the environmental hazards caused by the industrial effluents by removal of these toxic and carcinogenic dyes from the waste effluents. In this study, an eco-friendly superabsorbent hydrogel was prepared by using of sugarcane bagasse, two hydrophilic monomers, magnetic nanoparticle and methylene... 

Combustion and NOx emissions were simulated by quasi-dimensional and ratereaction methods respectively in a turbocharged CNG engine. Mean-value turbulence modeling was carried out during compression and combustion processes to simulate combustion process better. The most appropriate NG flame speed for the CNG turbocharged engine was applied and ignition delay was ended when flame radius became more than turbulence integral length scale. Hemispherical flame propagated from spark gap center and its intersection with reciprocating Mexican-hat piston bowl was calculated analytically. Thermal boundary layer, as a novel approach, was considered in the simulation and a better agreement of predicted... 

Ambient Intelligence is a new paradigm in information technology that creates environments able to detect and respond to users needs, actions, behaviors and feelings. In the presence of interaction conflicts, user trust plays an important role in accepting Ambient Intelligence environments for living, working, etc. Our main hypothesis is that higher conflict density results in a greater loss of trust in mixed-initiative Ambient Intelligence environments. In this thesis, we propose a comprehensive research method for measuring trust in Ambient Intelligence environments using both crowdsourcing and university surveys. We conduct both web-based experiments and physical experiments to gather... 

Due to the technology advancement and the large-scale application of lithium-ion batteries in recent years, the market demand for lithium is growing rapidly and the availability of land lithium resources is decreasing significantly. As such, the focus of lithium extraction technologies has shifted to water lithium resources. Among various aqueous recovery technologies, the lithium ion-sieve (LIS) technology is considered the most promising one. This is because LISs are excellent adsorbents with high lithium uptake capacity, superior lithium selectivity, and good cycle performance. TiO2-based nanotubes are an appropriate option for adsorbing lithium from solution due to their high specific... 

One of the challenges in the field of Ambient Intelligence is empowering end-user to determine the level of system interference in the control of the environment. One approach to answer to this challenge is using End-user Development to determine the rate of system intelligence as well as develop the behavior of the system by the user himself. In this way, the user introduces his intended behavior to the system so that the system operates in accordance with it.In this research, we have provided end-user development for an intelligent environment considering children as the end-user; for this purpose, we have designed a game-based user interface, allowing children to be involved in the... 

There are many industries in the world that produce colorized wastewater. Because of the complex structure and good solubility of dyes, such industries have problem treating this wastewaters. On the other hand, because of the toxicity of these materials for water living, dye removal from discharged wastewater of these industries is very important. In recent years, researchers have become interested in the synthesis of dye Nano adsorbents and they have published many works on this subject. The important parameters in the synthesis of such adsorbent include; non-toxicity, high adsorption capacity and easy separation. In this project, cellulose was extracted from bagasse and then CMC was... 

Centrifugal compressors have wide applications in the turbochargers, aircraft propulsion and petrochemical industry. Therefore it is important to design high efficiency centrifugal compressor. Knowledge of compressor performance at different conditions, energy losses and the contribution of each component of compressor in efficiency losses have of great importance.
In this research, different loss models of the centrifugal compressor were reviewed and investigated. Then 1D codes were developed based on the loss models, and performance characteristics of S2B Schweitzer and GT4082 Garret compressors at different conditions were achieved. In order to evaluate the modeling results,... 

Because of advantages of using new sources of energy in the country, especially for generating green energy, the use of wind energy for power generating in wind Fields is of great interest of current communities. For developing a wind power plant the first step is to locate and confirm the areas which possess enough potential for installing the wind turbines. For this purpose in the first chapter of this thesis an introduction to the basic principles of wind energy is noted then in the next chapter the physical relations to calculate the estimated reachable energy in the area is mentioned and in the third chapter the empirical methods for selection of the suitable sites are exhibited .in the... 

In this study an internal combustion rotary (Wankel) engine and its specifications is analyzed and the proper lubrication system is described. The acceleration acting on apex seals, and engine speed fluctuations together with the leading and trailing cells gas pressure forces are analyzed in the present work using the second Newton law. The research shows that cell gas pressure effects are important and inclusion of these effects will provide results which are more compatible with the reality and lead to a much more accurate analysis of the system. Theoretical calculations reveal that gas cell pressure forces represent about 78% of the overall calculated force and ignoring these pressure... 

Research for renewable energy has grown considerably over the last years. Osmotic energy is a form of renewable energy which is not yet used at commercial scale, but have a large potential to used at commercial scale soon. Osmotic power is a technique that converts the difference of molar free energy between fresh water and salt water into electricity. Pressure retarded osmosis (PRO) is the most frequently studied process of osmotic energy. In PRO two solutions of different salinities are brought into contact by a semipermeable membrane that only allows the transport of water and retain the solute. Positive developments in recent years initiated new studies to the exploitation of osmotic... 

In the modern world, one of the largest concerns is the ever depleting supply of oil. The automotive industry is especially impacted. In recent years the price of gasoline has fluctuated substantially and the price of crude oil has reached record highs. The high price of gasoline coupled with the uncertainty of its availability and future price have put a high priority on fuel economy of an engine. In addition the emissions released from internal combustion (IC) engines are polluting the atmosphere. Many studies have linked the greenhouse gases produced by an automobile engine to the partial destruction of our atmosphere and to global warming. As a result the US government is passing... 

Ambient intelligence is a new paradigm in human computer interaction in which smart actor interact with the surrounding environment and be helped in to reach their goals. One of the main principles in smart environments is the interaction between user and the system. Better interaction leads to a better user satisfaction. In explicit interaction, context plays an important role in interaction quality. One of the main parameter in interaction is the environment complexity. Environment complexity itself consists of other factor such as size of the room, number of devices, density of devices, size of the devices and etc. In this study, we have investigate the effect of two factor, environment... 

The purpose of this dissertation is to experimentally and numerically investigate the effect of molecular structure, composition, and physical and chemical properties of fuel on HCCI combustion. A well-equipped laboratory was set up to perform the required tests, capable of performing HCCI tests with different fuels. All tests used a single-cylinder diesel engine modified to operate in HCCI mode. Also, for numerical simulation, a chemical kinetic multi-zone model was developed to predict HCCI combustion behavior with appropriate accuracy. To investigate the effect of fuel chemical structure on HCCI combustion, three fuels, toluene, iso-octane and normal heptane, with entirely different... 

In atmospheric studies, chemical transport models are formulated to simulate the spatial and temporal distribution of pollutant concentrations. However, the performance of these models is strongly dependent on the input parameters such as emissions. Inverse modeling is a widely used mathematical approach for estimating model parameters by minimizing the discrepancy between model output and observations. For air quality studies, inverse modeling is often used for emission inversion as emissions are associated with significant amount of uncertainties.This research aims to estimate optimal values for anthropogenic PM2.5 emission through a four-dimensional variational (4D-Var) inverse modeling... 

Today, the world energy crisis, the need to optimize its consumption and discussion to reduce fuel consumption has become a vital issue. The conventional vehicle air conditioning system due to compressor in refrigeration cycle, which has causes a severe loss in engine useful power, increasing fuel consumption, etc. Therefore, the main goal of this project is the feasibility of the vehicle cooler replacement with the vapor jet refrigeration cycle. In this cycle, the energy required for completing the refrigeration cycle is provided from the heat of the water inside the radiator that is possible with conventional refrigeration cycle. The first stage of this project includes design and... 

In some activities, an almost free of any vibration environment is needed. Semi conductor production process and microelectronic microscopes are two examples in which a quiet environment is essential. The goal of this thesis is to attenuate ambient vibrations effectively and to prepare a suitable environment for two microelectronic microscopes. The designed system must be practical, economical and capable of being made in a short time interval. Considering mentioned properties a steel table with bolt connections supported on 4 air springs was built. To investigate dynamic properties, modal analysis was performed with the aid of finite element packages and experiments. To extract oscillations...