Sharif Digital Repository

Oil pump is a prominent part which has been described as a vehicle heart. Any malfunction or improper design may lead to engine failure. beside engine, proper design of oil route and lubrication system of vehicle, are main factor in engine design, which provide higher efficiency with lower pressure drop. lubrication system should be able to provide required pressure and flow of oil in vast range of engine rotation speed. also minimum energy waste in higher rpm is a key factor which happens due to reverse flow from output to input of pump in the relief valve. The aim of this thesis focus on design of oil pump and lubrication system of 4 cylinder 16 valve of 1600 cc inline engine. which is... 

Experiments were performed to explore the free convective hat transfer characteristics of water based nanofluids. Experiments of natural convection over a vertical flat plate with constant heat flux in water-based nanofluids with Ag and TiO2 nanoparticles were performed. Velocity boundary layer measured using PIV method. Also convective heat transfer coefficient obtained using three thermometers behind the wall. Various test cases with different heat fluxes on the wall are considered. Two volumetric concentrations of Ag nanofluid, 1% and 2%, and TiO2 nanofluid, 1% and 2%, were tested in the present study. It was shown that, with increasing nanofluid concentration, velocity boundary layer... 

At today’s crowded world, the importance of automobile transportation is obvious for all. The fossil fuel pollution crisis has increased the need for renewable-fueled engines with higher efficiency and lower emissions. Meanwhile, biofuels have received more attention for reasons such as carbon dioxide cycling, Affordability and availability. However, despite these benefits biofuels require crops such as corn or potatoes to produce, which in turn produce other environmental pollution. On the other hand, concerns have been raised as to whether the use of these fuels increases the amount of other pollutants, except for carbon dioxide, or not. Extensive researches in this field by experimental,... 

Considering the fact that there is a blood flow inside the vessels it is possible that blood flow is always associated with fouling and this may decrease the blood flow when a blood vessel is injured, the cells of your blood bond together to form a blood clot. The blood clot helps you stop bleeding. Blood clots are made of a combination of blood cells, platelets (small sticky cells that speed up the clot-making process), and fibrin (protein that forms a thread-like mesh to trap cells). Doctors call this kind of blood clot a “thrombus.” We study the effects of different parameters on the deposition of Nanoparticles on the surface of a bump in the blood vessels by the magnetic field. The... 

Lithium-ion batteries have the ability to store a significant amount of energy and work at high power, which has led to the wide spread of their use in various industries. In high-power applications, battery heat management increases lifespan, safety, and reduces battery power loss. In this study, the heat management of a very common and widely used 18650 battery using multi-layered phase change material has been investigated. The reason for using multiple layers is that each phase change material has its own weaknesses in addition to its advantages. It is expected that with the proper use of several phase change materials in the thermal management system, the materials will reduce the... 

Providing fresh water, ending fossil fuels, using renewable energy and achieving a clean biological environment in different parts of the world especially in Iran beside having access to many saline water sources, Shows the need for research in the field of solar still desalination. The goal of current study is to increase the performance of the solar still system through the use of an energy storage system and an additional condenser. Adding an additional condenser to a conventional solar still lead to an increase in the rate of evaporation and consequently increase the production of the system. Also, by collecting distilled water from the sidewalls, the amount of water produced... 

In this thesis we want to discuss about a new approach about information. Using this approach, Scott Muller builds his formalism on two basic concepts: distinguishablity and symmetry. His claim is that there is an inverse relation between symmetry and information. It means that if we have a symmetric system we need less information (Than an asymmetric system) to describe it. Here, we are going to explore the role and significance of symmetry in probabilistic distributions of the double-slit experiment, and we want to show if there is a predetermined relation between symmetry and information or not.
 

The purpose of this project is designing a controller for a floating offshore wind turbine to exctract maximum power from wind energy in the first operating region of wind turbine. The NREL 5 MW OC3-Hywind floating wind turbine with BARGE platform will be used for this project. By using Turbsim software, proper wind profile for the first operating region of wind turbine will be produced. This profile will be excecuted for the FAST software that is simulates the mechanical part of wind turbine. By implementing the doubly fed induction generator in Simulink enviroment and designing the controller for doubly fed induction generator, the desired torque for maximizing the exctraction power of... 

Fog computing environment consists of several devices which distribute across an arbitrary topology. Each of these devices is capable of carrying out a designated computation simultaneously with other devices. One of the common ways of describing a computation is through the usage of workflows. Workflow is a flexible and formal way of modeling tasks and their requirements for execution. A workflow is essentially a DAG. Therefore, it can model the data dependency between tasks quite accurately. The complex structure of a workflow in conjunction with the homogenous nature of devices in a fog environment makes it difficult to find a resource management algorithm to minimize execution time, used... 

Liquid marbles are droplets enwrapped by a layer of micro/nanoparticles. Due to the insulation of inner fluid from the environment, the lower evaporation rate of the fluid, and the capability of motion even on hydrophilic surfaces, these liquid marbles, as an alternative to conventional droplets, have attracted the attention of researchers in digital microfluidics. Utilizing ferrofluid as the liquid core of the liquid marbles enables remote control over the liquid marbles by an external magnetic field. In this research, the dynamic behavior of ferrofluid liquid marbles under the magnetic field generated by an electromagnet is investigated. In this research, governing physics on the motion of... 

This project focuses on the design of fuel drop tanks for airplanes that add minimal drag and positive lift to the flying object. This will obviously effect the stability and dynamic performance of the airplane. To reduce adverse dynamic effects the tank was divided to several segment with a special emptying sequence. The add-on tank has to have no interference with the object existing systems and require minimum structural changes in the object. Several designs were proposed and the one gaining highest marks was selected. The flow field and the dynamic behavior of combined vehicle and drop tanks were studied using FE simulations. The result shows that adding a drop tank with optimized... 

Right from the start, customer need has been the center of focus for every firm. It’s hard to find a single firm which is not focused and customer centric. Firms are spending millions of dollars every year to make customer surveys and interviews to find out customer needs, new product development and brand perceptions. After the invention of the internet and the rise of home computers people started to act differently. Most of the purchases went online and customer reviews flooded over the internet. They freely express their mind on websites which is a rich resource for market researchers and marketing firms. UGC is rich enough to analyze customer’s thoughts and needs. The volume of UGC has... 

Cancer can be defined as a stochastic phenomenon. Thus, the tumor growth can be defined as a stochastic process. A Cancer tumor can be analyzed by its geometric shape. Furthermore, computing fractal dimension of shapes is a useful technique to analyze chaosity and complexity of shapes. This approach can be used to compare results from laboratory with simulated results of a mathematical model. A stochastic model of tumor growth will be presented. And some geometrical properties will be analyzed through computer simulation of the model  

Many have claimed that quantum mechanics is playing a non-trivial, i.e. further from merely governing atomic and molecular realm, in living. If so, clearly quantum mechanics should have played a key role in the origin of life especially in the transition from chemical evolution to biological (Darwinian) evolution. Long before quantum aspects of living systems came to focus, It was known that all the amino acids are right handed and all the sugars are left handed in living systems. Bio-molecules having the same sense of chirality, i.e. optical activity, are called biohomochirality. Detailed studies on the structure and functioning of biomolecules buttressed the idea that the selection of... 

The effects of combined task demands on the way muscles are recruited to balance external loads during posture and movement is of great importance in quantitative analysis of upper arm function. Pain and disability of shoulder joint is becoming more important as population spends more often interacting with computers in seated position and carrying repetitive tasks using upper extremities. Shoulder joint that is more dependent on the muscles for its normal function than other joints such as hip due to its small articular surface and large range motion has been used here to study its coordination during isometric exertions. Since, the numbers of tasks that could be performed are enormous. In... 

In this thesis, nitrogen-doped carbon quantum dots were synthesized from anhydrous trisodium citrate and arginine in water solvent by the hydrothermal method, which was used to develop an on-off-on fluorescence sensor. The hydrothermal method is a suitable method for the synthesis of nitrogen-doped carbon quantum dots due to its affordability, availability, rapidity, and safety. Characterization of nitrogen-doped carbon quantum dots was divided into two parts: in the first part, optical properties were investigated using fluorescence photoluminescence (PL) spectrometer and ultraviolet-visible spectrometer (UV-Vis), and in the second part, Fourier transform infrared spectrometry (FTIR),... 

The main purpose of this thesis is to analyze the total productive maintenance based on computerized maintenance management system. At first, a detailed study on total productive maintenance is performed and then the requirements of this maintenance strategy are specified. Also, a computerized maintenance management system is defined which can help total productive maintenance to reach to its requirements. Finally, a conceptual model and entity-relationship model for computerized maintenance management system data base has been created  

Today microbubbles are broadly used as ultrasound contrast agents. These bubbles enhance the image resolution of B-mode pictures. Flow focusing in microchannels could provide us the goal of one-size bubbles generation. Microbubbles could use as tracers in Echo_PIV method to determine the velocity profile in main body vessels such as carotid. In this paper we introduce a new production method to fabricate a low-cost microchannel for preparing Microbubble contrast agents (less than 50 microns) by using some surface active agents and a viscosity enhancing material to obtain appropriate Microbubbles with desired life time and stability for any in vitro infusion for velocity measurement. By... 

In the present study, the axisymmetric liquid gas/air diffusion flame in the presence of fuel concentration oscillations and velocity perturbations has been investigated experimentally. Several industrial combustions take a place by diffusion mechanism which necessitate scientists to make far better understanding of diffusion flames. In order to study diffusion flames, the instrument with two separated lines of fuel and air has been developed. Nitrogen is used for fuel dilution oscillatory with pulse of 1, 2, and 4 Hz frequencies. The pulse duration effects on flame structure are also studied. The flame shape has been captured by high speed camera and the results are processed by image...