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    Design and Implement of an Ultra Low Ripple Power Supply for Cathode of Microwave Tube

    , M.Sc. Thesis Sharif University of Technology Jalali, Saeed (Author) ; 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 Amerian, Pourya (Author) ; 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 Toliat, Ali (Author) ; 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... 

    EXAF: A search engine for sample applications of object-oriented framework-provided concepts

    , Article Information and Software Technology ; Volume 75 , 2016 , Pages 135-147 ; 09505849 (ISSN) Noei, E ; Heydarnoori, A ; Sharif University of Technology
    Elsevier  2016
    Abstract
    Object-oriented application frameworks, such as Java Swing, provide reusable code and design for implementing domain-specific concepts, such as Context Menu, in software applications. Hence, use of such frameworks not only can decrease the time and the cost of developing new software applications, but also can increase their maintainability. However, the main problems of using object-oriented application frameworks are their large and complex APIs, and often incomplete user manuals. To mitigate these problems, developers often try to learn how to implement their desired concepts from available sample applications. Nonetheless, this introduces another hard and time-consuming challenge which... 

    Classification of Motor Imagery in Electroencephalogram Signal Based on Spatio-temporal Feature selection Using Elastic Net

    , M.Sc. Thesis Sharif University of Technology Noei, Shahryar (Author) ; Jahed, Mehran (Supervisor)
    Abstract
    Motor imagery causes Event related Synchronization/Desynchronization (ERS/ERD) in Electroencephalogram (EEG) signal. These potentials can be used as an input for a Brain Computer Interface (BCI) system. To do so, it is necessary for these inputs to be correctly classified. The quality of classification is severely affected by the features extracted. Common Spatial Patterns (CSP) algorithm is often used for this task. Some of this method disadvantages are neglecting non-stationary properties of EEG signal and its proneness to overfitting. Additionally, its success is highly dependent on the frequency band that the algorithm is performed in. The most suitable sub band is interchangeable... 

    Investigation and modeling of the thermal conductivity of PP/clay nanocomposites and PP/MWCNT nanocomposites

    , Article E-Polymers ; Dec , 2010 ; 16187229 (ISSN) Shahryar Nejad, S ; 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 Ziaoddini, Mojtaba (Author) ; 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 Implementation of a Search Engine for Sample Applications of Object-Oriented Framework-Provided Concepts

    , M.Sc. Thesis Sharif University of Technology Noei, Ehsan (Author) ; Heydarnoori, Abbas (Supervisor)
    Abstract
    An object-oriented application framework, like Eclipse, not only provides a framework for designing and implementing new applications, but also decreases the time and the cost of developing new software applications. Moreover, theseframeworks increase the maintainability of software systems. Therefore, their popularity is on the rise. The main problem of using object-oriented application frameworks is the lack of proper documentations and guides. Thus, developers often try to learn how to implement their desired concepts (e.g., Context Menu) from available sample applications. This leads the programmers to another problem which is finding the sample applications. Finding a proper sample... 

    Design and Implement of Voltage Ripple Measuring System for Power Supply of Microwave Tubes

    , M.Sc. Thesis Sharif University of Technology Ahmadi Someh, Saeed (Author) ; 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... 

    Synthesis and characterization of bagasse poly(methyl methacrylate) graft copolymer

    , Article Macromolecular Symposia ; Volume 274, Issue 1 , 2008 , Pages 49-54 ; 10221360 (ISSN) Sarvi, I ; Pourjavadi, A ; Noei Aghaei, M. A ; Sharif University of Technology
    2008
    Abstract
    Graft copolymerization of methyl methacrylate (MMA) was carried out on bagasse fibers in an aqueous medium using eerie ammonium nitrate (CAN) as initiator under a neutral atmosphere. In order to obtain the optimum condition for graft copolymerization, the effects of initiator concentration, temperature, time of reaction, and monomer concentration were studied. The maximum grafting percent was found to be 122%. The bagasse grafted poly(methyl methacrylate) was characterized by FTIR and its thermal behavior was characterized by TGA. Copyright © 2008 WILEY-VCH Verlag GmbH & Co. KGaA  

    Classification of EEG signals using the spatio-temporal feature selection via the elastic net

    , Article 2016 23rd Iranian Conference on Biomedical Engineering and 2016 1st International Iranian Conference on Biomedical Engineering, ICBME 2016, 23 November 2016 through 25 November 2016 ; 2017 , Pages 232-236 ; 9781509034529 (ISBN) Noei, S ; Ashtari, P ; Jahed, M ; Vahdat, B. V ; Sharif University of Technology
    2017
    Abstract
    Effective classification of motor imagery electroencephalograph (EEG) data is an important challenge. Spatial filtering such as Common Spatial Pattern (CSP) and its variants are commonly used for this task. However, CSP effectiveness depends on the subject-specific frequency band. Even by optimally selecting a subject-specific frequency band, this method still fails for some subjects. On the other hand, some studies suggest that temporal features may discriminate classes more efficiently. This work proposes a hybrid method based on elastic net and Least Absolute Shrinkage and Selector Operator (LASSO) to optimally select between spatial and temporal features. This algorithm uses joint... 

    Using Automata-based techniques for Energy Management in Embedded Systems

    , M.Sc. Thesis Sharif University of Technology Nazeri Tile Noei, Mohammad (Author) ; Ejlali, Ali Reza (Supervisor)
    Abstract
    These days, societies prefer to use systemsthat provide more utilities with rapid processing. This lead to make large volume of information to process.And also, the number of processors used in embedded systems is more than the number of them in PC. Gradually, the embedded systems own complex processor. On the other hand, according to the Moore’s law, the number of transistors on a chip doubles every eighteen months. That lead to be more complex. And also, based on predictions, the amount of software used in most of electronic devices doubles every two years.The increasing of amount of information and high-performance expecting havecaused increaseprocessing. The increasing requires more... 

    Energy analysis of part flow and full flow Humid Air Turbine Cycle (HAT)

    , Article 2006 ASME 51st Turbo Expo, Barcelona, 6 May 2006 through 11 May 2006 ; Volume 4 , 2006 , Pages 319-327 ; 0791842398 (ISBN); 9780791842393 (ISBN) Noei Aghaei, V ; Khaledi, H ; Bakhtiari, B ; Ghofrani, M. B ; Sharif University of Technology
    2006
    Abstract
    Current researches on the development of gas turbine related power plants such as HAT cycle and Combined Cycle are aimed to increase the plant efficiency and output power, while reducing the cost of power generation and emission. Humid air turbine cycle (HAT) is one of innovative cycles, which are able to provide a substantial power boost of the system and an efficiency rise of several percentage points. In order to perform energy analysis of Full Flow HAT cycle and Part Flow HAT cycle an advanced thermodynamic model is developed, which is enabling evaluation of behavior of Full Flow and Part Flow Humid Air Turbines and predicting the influence of operational parameters in the performance of... 

    On the graphs with minimum sombor Index

    , Article Match ; Volume 88, Issue 3 , 2022 , Pages 553-559 ; 03406253 (ISSN) Aashtab, A ; Akbari, S ; Madadinia, S ; Noei, M ; Salehi, F ; Sharif University of Technology
    University of Kragujevac, Faculty of Science  2022
    Abstract
    For a graph G the Sombor index of G is defined as (Formula Presented) , where d(u) is the degree of u in G. In the current paper, we study the structure of a graph with minimum Sombor index among all graphs with fixed order and fixed size. It is shown that in every graph with minimum Sombor index the difference between minimum and maximum degrees is at most 1. © 2022 University of Kragujevac, Faculty of Science. All rights reserved  

    Photoacoustic signal enhancement: Towards utilization of low energy laser diodes in real-time photoacoustic imaging

    , Article Sensors (Switzerland) ; Volume 18, Issue 10 , 2018 ; 14248220 (ISSN) Manwar, R ; Hosseinzadeh, M ; Hariri, A ; Kratkiewicz, K ; Noei, S ; Avanaki, M. R. N ; Sharif University of Technology
    MDPI AG  2018
    Abstract
    In practice, photoacoustic (PA) waves generated with cost-effective and low-energy laser diodes, are weak and almost buried in noise. Reconstruction of an artifact-free PA image from noisy measurements requires an effective denoising technique. Averaging is widely used to increase the signal-to-noise ratio (SNR) of PA signals; however, it is time consuming and in the case of very low SNR signals, hundreds to thousands of data acquisition epochs are needed. In this study, we explored the feasibility of using an adaptive and time-efficient filtering method to improve the SNR of PA signals. Our results show that the proposed method increases the SNR of PA signals more efficiently and with much... 

    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) Mehrpour, S. R ; 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,... 

    Universal in vivo textural model for human skin based on optical coherence tomograms

    , Article Scientific Reports ; Volume 7, Issue 1 , 2017 ; 20452322 (ISSN) Adabi, S ; Hosseinzadeh, M ; Noei, S ; Conforto, S ; Daveluy, S ; Clayton, A ; Mehregan, D ; Nasiriavanaki, M ; Sharif University of Technology
    2017
    Abstract
    Currently, diagnosis of skin diseases is based primarily on the visual pattern recognition skills and expertise of the physician observing the lesion. Even though dermatologists are trained to recognize patterns of morphology, it is still a subjective visual assessment. Tools for automated pattern recognition can provide objective information to support clinical decision-making. Noninvasive skin imaging techniques provide complementary information to the clinician. In recent years, optical coherence tomography (OCT) has become a powerful skin imaging technique. According to specific functional needs, skin architecture varies across different parts of the body, as do the textural... 

    Photoacoustic signal enhancement: Towards utilization of very low-cost laser diodes in photoacoustic imaging

    , Article Photons Plus Ultrasound: Imaging and Sensing 2017, 29 January 2017 through 1 February 2017 ; Volume 10064 , 2017 ; 16057422 (ISSN); 9781510605695 (ISBN) Hariri, A ; Hosseinzadeh, M ; Noei, S ; SENO Medical Instruments, Inc.; The Society of Photo-Optical Instrumentation Engineers (SPIE) ; Sharif University of Technology
    SPIE  2017
    Abstract
    In practice, photoacoustic (PA) waves generated with cost-effective, low-energy laser diodes, are weak and almost buried in noise. Reconstruction of an artifact-free PA image from noisy measurements requires an effective denoising technique. Averaging techniques are widely used to increase the signal-to-noise ratio (SNR) of the weak PA signals but the process is time-consuming and in case of very low SNR measurements, hundreds/thousands of data acquisition epochs needed to provide the required data In this study, we propose to use adaptive denoising methodology in which adaptive line enhancers (ALE) has been embedded for increasing the SNR of PA signals in very low-cost PA systems. Our...