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mehrvand--shahryar
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Hydro-economical Method for the Optimal Capacity Design of Small Hydropower Plant (Case Study: Kohneh Lahijan Hydropower Plant)
, M.Sc. Thesis Sharif University of Technology ; Shamsai, Abolfazl (Supervisor)
Abstract
In this thesis, we determine the optimal capacity of the power plants considering site specifications and Flow Duration Curve and evaluating economic parameters. Finally a design with more sufficient economical and hydrualical performance would be selected. The optimization algorithm used in this thesis is called "Charged System search" that is one of the newest meta-heuristic algorithms. This algorithm is inspired by the coulomb and gauss's laws of electrostatics in physics and utilizes a number of charged particles which influence each other based on their fitness values and their separation distances considering the governing law of coulomb.The proposed method in this thesis can be...
Design and Implement of an Ultra Low Ripple Power Supply for Cathode of Microwave Tube
, M.Sc. Thesis Sharif University of Technology ; Kaboli, Shahryar (Supervisor)
Abstract
The purpose of this Thesis is designing and constructing of high voltage power supply with very low ripple. Proposed method of this thesis is formed of two sections. In this proposed structure, in first section, structure is on basis of diodes rectifier that has been used for producing main portion of output load energy. Second section uses with aim of regulating of first stage voltage. In attention to existence of noises and available offsets in different sections of proposed circuits, model is basis of two stages structure. Sampling of output voltage by using of resistance divider for main loop of circuit has been done. So noises and offsets available in circuit act as prevented factor...
Analysis of the Challenges in the Design of High Power and High Frequency Inverters
, M.Sc. Thesis Sharif University of Technology ; Kaboli, Shahryar (Supervisor)
Abstract
Power Inverter or DC to AC voltage converter is one of the most important and widely discussed topics in the world of power electronics and systems such as DC/DC converters. Increasing the switching frequency of the inverter, in addition to its many advantages, also creates challenges that will be addressed in this dissertation. To build a high frequency yet reliable inverter, you need accurate and comprehensive information about the inverter circuitry, parasitic elements, switches and their behavior against fault conditions such as short circuit, protection requirements and etc.In this dissertation, several MOSFET transistors is shorted under various test conditions while parameters...
Improving the Performormance of an Ultra Narrow Pulse Generator based on Transmission Lines
, M.Sc. Thesis Sharif University of Technology ; Kaboli, Shahryar (Supervisor)
Abstract
The ultra-narrow pulse generator have being used for direct production of pulsed power. One of these structures is being used to make a bipolar pulse and its main feature is the utilization of the real transmission lines (not PFN) with an intricate structure that caused volume to be compressed. It is desired to reach an appropriate design by analyzing the output waveform and its relation to the transmission line parameters. A little piece of work has been done in the past but there were some differences from our anticipations in the waveforms, like pre-pulse, long rise and fall times and overshoot that caused by some non-idealities in the structure. What we have done in this project is to...
Investigation and modeling of the thermal conductivity of PP/clay nanocomposites and PP/MWCNT nanocomposites
, Article E-Polymers ; Dec , 2010 ; 16187229 (ISSN) ; Golzary, A ; Sharif University of Technology
2010
Abstract
In this study, polypropylene/clay nanocomposites were prepared by melt blending method and their thermal conductivity and the thermal conductivity of polypropylene/multi-wall carbon nanotube (MWCNT) nanocomposites were investigated and modeled. It is found that the thermal conductivity of the PP/Clay and PP/MWCNT nanocomposites is increased with increasing temperature. The thermal conductivity of the nanocomposites is improved due to incorporation of nanoclay and MWCNT compared with pure PP matrix
Analysis and Improvement of Output Voltage Ripple in High Voltage DC Power Supply
, M.Sc. Thesis Sharif University of Technology ; Kaboli, Shahryar (Supervisor)
Abstract
The TWT is highly sensitive to the ripple amplitude of its power supply output voltage. If the amplitude of the output voltage's ripple exceeds a certain limit, the amplitude of the undesired harmonics in the power spectrum of the TWT is greatly increased. Increasing the amplitude of undesired harmonics in the TWT output power spectrum reduces the accuracy and performance of the TWT. Therefore, for optimum TWT performance, a low-ripple power supply is essential. Typically, a low-frequency rectifier or high-frequency switching structure is used to build a high-voltage DC power supply. In this thesis, the different structures of high voltage DC power supplies are studied. Next, by focusing on...
Design and Implement of Voltage Ripple Measuring System for Power Supply of Microwave Tubes
, M.Sc. Thesis Sharif University of Technology ; Kaboli, Shahryar (Supervisor)
Abstract
Mostly, the high voltage DC power supplies have output voltage ripple. In such an applications like power supply of microwave lamps in radar systems, low output voltage ripple is an important point of operational characteristics. On the other hand, measuring the low voltage ripple will be a challenge that can lead to recognize of its reasons and reduce its amplitude. In this thesis, different ways of ripple measurement constraints is described, then a method based on high pass filters for output voltage ripple measurement is implemented. The impact of components tolerance and their parasitic components like shunt parasitic resistance of a capacitor in filter operational characteristics is...
Efficient bio-nano hybrid solar cells via purple membrane as sensitizer
, Article BioNanoScience ; Vol. 4, issue. 1 , 2014 , pp. 71-77 ; ISSN: 21911630 ; Molaeirad, A ; Mohamadpour, R ; Khayati, M ; Mehrvand, J ; Sharif University of Technology
2014
Abstract
Bacteriorhodopsin is a heptahelical protein found in the purple membrane of Halobacterium salinarum. The performance of bacteriorhodopsin was evaluated as a sensitizer in dye-sensitized solar cells (DSSCs). Bacteriorhodopsin was efficiently immobilized on the titanium dioxide nanoparticles and then tested for its ability to convert solar radiation to electricity. The photovoltaic performance of DSSC based on the bacteriorhodopsin sensitizer has been examined. Under AM1.5 irradiation, a short-circuit current of 0.28 mA cm−2, open-circuit voltages of 0.51 V, fill factor of 0.62, and an overall energy conversion efficiency of 0.09 % are achieved employing platinum as a counter electrode. Carbon...
Descriptive epidemiology of traumatic injuries in 18890 adults: A 5-year-study in a tertiary trauma center in Iran
, Article Asian Journal of Sports Medicine ; Volume 6, Issue 1 , 2015 ; 2008000X (ISSN) ; Nabian, M. H ; Oryadi Zanjani, L ; Foroughmand Araabi, M. H ; Shahryar Kamrani, R ; Sharif University of Technology
2015
Abstract
Background: Basic epidemiological data can provide estimates when discussing disease burden and in the planning and provision of healthcare strategies. There is little quantitative information in the literature regarding prevalence of traumatic injuries from developing countries. Objectives: The aim of the current preliminary study was to reveal the prevalence and age and gender distribution of various traumatic injuries in a tertiary referral orthopedic hospital in Iran. Patients and Methods: In a prospective descriptive study, all traumatic injured patients attending the Orthopedic Trauma Unit of our center in a five year period were included. Demographic details, the cause of injury,...