Sharif Digital Repository

A simple equation of state (EoS) has recently been introduced (J. Phys. Chem. B 2009, 113, 11977–11987) as (Z-1) v^2=e+f⁄ρ+gρ^2, where Z≡pv⁄RT is the compressibility factor, v=1⁄ρ is molar volume, and e, f, and g are temperature dependent parameters. This EoS has been found to be accurate for all types of nano- and bulk- solids and bulk fluids, in the entire temperature and pressure ranges for which experimental data are reported, except for the isotherms within the critical region.
The aim of this work is to investigate the validity of a 3-term expression similar to the mentioned EoS for both thermal and internal contributions to the compressibility factor, separately. Such... 

In this Thesis, an unmanned multicopter with a new structure is modeled and a nonlinear controller is designed for it to track the trajectories precisely. The multicopter in this thesis, has six propellers with a hybrid propulsion system (a combination of fuel and electric propulsion system) that has the ability to carry more payload and maintain more flight duration compared to electric multicopters. In the beginning, the performance characteristics and technical specifications of the hexacopter are presented. For modeling, first the equations of six degrees of freedom movement of the hexacopter are derived by the Newton-Euler method. In the next step, the forces and torques applied to the... 

Fatigue life and crack growth retardation due to periodic tensile overload that superposed on constant amplitude cycles has been investigated. The tests were performed using C(T) specimens made of 7075 aluminium. All periodic overload tests were carried out at the same spacing between overloads and the effect of overload ratio on fatigue life has been investigated. Results of experiments revealed that the at low and high overload ratios, crack growth rate is relatively high and there is an optimum OLR that maximize interaction and thus minimize FCGR. Whit OCR-1=50, overload ratio of 1.85 led to maximum interaction and resulted in 219% increase in specimen's life relative to CA loading. Also... 

Diabete is disability in the body to produce insulin or use it. Body insulin hormone needed to convert starch, sugar and other foods to energy and thus the body is functioning properly. Considering this incurable disease and its complications, many doctors and researchers trying to control the disease, reduce complications and to create favorable conditions and appropriate solutions for preventing its expanding and also strengthening patients mentally. Be destroyed in digestive system, insulin can not through tablets or similar cases received. The best way known to enter insulin to the body, is injection. This project is about a device to reduce the level of blood glucose in patients with... 

Attitude control of rigid bodies is a complicated but attractive problem in dynamics. One of its main practical applications is in satellite attitude control and specifically in space telescope orientation control. Using fuel thrusters is not only expensive in most cases, but also it cannot be considered as an appropriate solution from reliability and economic aspects in long-term applications such as space telescopes and telecommunication satellites. On the other hand, magnetic torquers and momentum wheels cannot be utilized for rapid and large maneuvers due to their inability in generating large torques, which are needed in such maneuvers. As a result, another type of attitude control... 

The goal of using speed humps is to reduce the velocity of cars to allowable value. Reducing the speed more than necessary before arriving at the hump, causes losing kinetic energy whose compensation needs consuming more fuel. In fact, the total fuel consumption of vehicles is noticeable and it expresses the need for allowable speed definition to prevent wasting fuel. In this project, using different methods in engineering design and by defining allowable speed, an intelligent speed hump is designed and selected from different patterns which may remain protuberant or become like the road surface in level. The parts considered for this hump are selected simple to lower the cost of... 

In this research, the effect of variable stiffness and damping, in suspension system, on car performance was studied. The optimization of car performance was obtained by minimization of an objective function including the body acceleration, suspension travel and tire deflection. Firstly, considering the stochastic input for a quarter car model, minimization of the objective function was done by changing the stiffness and damping coefficients in the frequency domain. The Linear Quadratic Regulator (LQR) method was implemented to minimize the objective function. In order to supply the active force obtained by optimization, different semi-active designs, in which stiffness and damping were... 

In recent decades, emission from automobiles is considered one of the main reasons for global warming. One of the ways to decrease the fuel consumption of the vehicle, increase the power train efficiency and vehicle acceleration is to use Continuously Variable Transmission (CVT) and infinitely variable transmission (IVT). Previous inquiries include investigate miscellaneous types of continuously variable transmissions and their efficiency and different ways of combination of CVT and other power trains in order to create an IVT. The aim of this research is to optimize one kind of IVT transmission. At first, different state of combination of IVT portions will be investigated. Then, a model is... 

Hydrophilic polymers are widely used in enhanced oil recovery (EOR) processes to increase water viscosity during polymer flooding. However, these polymers increase the viscosity of injected water in undesirable strands, before reaching considerable positions that make some problems in polymer flooding process such as thermal, mechanical, bacterial degradation, surface absorption and undesirable plugging. In this study, a novel core-shell structure of polyacrylamide as an active polymer and nanoscale coating polystyrene as a shell polymer was designed and prepared to intelligently control mobility ratio in oil reservoirs and overcome weakness and limitations of classical polymer flooding.... 

Cache memory is one of the most important parts of the microprocessors. Caches improve performance by bringing data and instructions near the processors and decreasing the access time to data and instructions. But caches are also vulnerable to some kind of error called soft error. When an error happens in a cache, suddenly can propagate throughout the system and affect the integrity and reliability of the overall system. There are actually two types of errors in cache memories, permanent (hard) errors and transient (soft) errors. Previous studies have shown that about 92% of system reboots are initiated by soft-error occurring in cache memory. Soft-errors have two main sources, alpha... 

Pyroshock Test is one of important environment tests in satellite design process.pyroshock or pyrotechnic shock is one of loads that exerted on spacecraft and it's subsystems during launch process. pyroshock can cause failure in some subsystems like sensitive electronic parts, solar cells and so on. For this reason it's necessary to make sure about strength of component under pyroshock which can be done by pyroshock simulator.The purpose of this research is to design a pyroshock simulator that can simulate a pyroshock with given SRS (Shock Response Spectrum) for satellite components.Requirements and constraints for design have been defined such as test item dimensions,weight range and also... 

Propylene Copolymers and terpolymers with small amount of 1-butene& ethylene can greatly improve the properties of polypropylene material such as low temperature toughness, printing performance, transparency, process ability and so on, leading to expanding of its application. Poly(propylene-co-1-butene) performance intensely relies on its composition and chain structure. The copolymerization catalyzed by Ziegler-Natta catalyst, which is a multy-active central system. The Ziegler-Natta catalyst TiCl4/ Mg(OEt)2/ DIBP was used for copolymerization. The microstructure of copolymers were characterized by FTIR. The influence of different comonomer ratios on the copolymerization has been... 

Pyrotechnic devices are widely used by the aerospace and defense industries and consist of a broad family ofsophisticated devices using self-contained energy sourcessuch as explosives and/or pyrotechnic compositions.Pyrotechnic shock, or pyroshock, is the transient oscillatoryresponse of a structure to loading (high frequency, highmagnitude stress waves) induced by the detonation ofpyrotechnic devices incorporated into or attached to thestructure.Pyroshock Test is one of importantenvironmental tests in satellite design process. Pyroshock is one of loads that exerted on spacecraft and it's subsystems during launch process. Pyroshock can cause failure in some subsystems like sensitive... 

One of the robots that has become more important recently is radio control helicopters. According to the intrinsic unstability of these helicopters and possibility of crash with the surroundings, it is needed to have a device which the helicopter can be fixed to so the ability of motion is reduced and a safer flight is achieved. In the recent applications of these helicopters, the autonomous flight ability of these devices is more noticed; and a lot of controllers are proposed to achieve this goal. It is obvious that these controllers are needed to be tested; and benchmarking a controller in the software simulation environment is not reliable; so a test stand is needed.
In this project a... 

Recently lots of studies have been done on driving cycles and parameters affecting pollutants emission and fuel consumption. Due to changes of driving behavior and traffic situations, it’s necessary to update driving cycle of a city to obtain more accurate simulation and analysis results. In this project, first of all driving cycle of Tehran city is developed using three different methods. These methods include choosing representative microtrips from specified traffic situations, clustering and choosing representative microtrips from all available data. Results show that using clustering method is more accuarate and parameters of the cycle developed using this method is closer to measured... 

Modern science and technology’s desire is increasing for Control Algorithms Testing Instruments which allow testing autonomics due to advancement in robotic science and increased application for autonomics. In this Thesis, a manufactured tester is equipped with sensors to allow data acquisition and Control algorithms tests for RC helicopters, which are a variety of autonomics. For this purpose; a manufactured 3-DOF tester was used and for control application purposes one degree of freedom was added and it was made to 4-DOF. Also, Mechanical defections which cause vibration resonance failing was solved. In the end, a data acquisition system with an appropriate rate for signal gathering and... 

One of the important experiments on satellites and their components is testing of their resistance to shock wave known to pyroshock. Pyroshock is transient response of a structure to a high frequency and high acceleration shock wave that is created by the action of a member of pyrotechnics in the satellite structure. This research is for design, construction and calibration of a pyroshock simulator apparatus which is done with specific requirements and aims. For this purpose, in first step an experimental test is done and validation of computer simulation is obtained by using results of test. By use of computer simulation tool, new design is presented. After constructing the apparatus and... 

In recent years passenger cars have been known as the main source of air pollution in urban areas. Despite all the research and efforts in minimizing the fuel consumption and emissions of internal combustion engines (ICE), this is merely a temporary solution. The permanent solution to overcome these disavantages is the use of electric vehicles (EV). The main downside of using electric vehicles is their short driving range. Multi-speed transmissions can be adopted to overcome this problem. Continuously variable transmissions (CVT) and infinitely variable transmissions (IVT) have been proven to enhance fuel economy in ICE vehicles and a great deal of research is being conducted to maximize... 

In this research the vibration of rotating and non-rotating shells was investigated. In the non-rotating shells field, the vibration of joined cylindrical shells and joined conical shells that each sections of them has independent material, thickness, length and angle were investigated. By analyzing the free vibration of joined conical shells, we can perform the free vibration analysis on every complex thin-walled geometry.In the rotating shells field, first the governing equations of the rotating conical shells are derived and then, the vibration of rotating cylindrical-conical shells and joined conical shells were investigated. The governing equations of rotating conical shells and...