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Nonuniform line generator for high-power RF applications
, Article IEEE Transactions on Plasma Science ; Volume 46, Issue 1 , 2018 , Pages 64-71 ; 00933813 (ISSN) ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Line generators were attractive structures for high-power radio frequency (RF) pulse generation for two decades. Due to some disadvantages, there has been little attention to this type of generator for a relatively long time. In this paper, a nonuniform line generator is used which resolves some of the main shortcomings of conventional line generators. The considered generator can generate RF pulses at higher frequencies with considerably higher repetition rates. Furthermore, the implementation of nonuniform line generators is significantly easier than that of their conventional counterparts. Measurement results for three nonuniform line generators are presented. The possibility of...
A disambiguation technique for passive localization using trajectory analysis
, Article IEEE Transactions on Aerospace and Electronic Systems ; 2018 ; 00189251 (ISSN) ; Behnia, F ; Sharif University of Technology
2018
Abstract
In some well-known passive localization methods, when the number of equations equals the number of unknown object coordinates, there arise finite number of possible solutions. A localization disambiguation technique is required to identify the correct solution in these cases. As an example, the exact solution of time-difference-of-arrival (TDOA) based equations for four receiver sites, leads to a couple of solutions with only one of them being the true target position. This ambiguity, conventionally is resolved by using angle-of-arrival (AOA) measurements or using an additional receiver site which increase the cost and complexity of the system. In this paper a localization disambiguation...
Single-site source localisation using scattering data
, Article IET Radar, Sonar and Navigation ; Volume 12, Issue 2 , February , 2018 , Pages 250-259 ; 17518784 (ISSN) ; Behnia, F ; Sharif University of Technology
Institution of Engineering and Technology
2018
Abstract
Passive localisation of non-cooperative targets through their electromagnetic emissions is an attractive issue. This localisation task can be carried out using multitude of receiver sites being linked together. This multiplicity, however, brings about difficulties in organising and coordinating the sites. One can even claim that the method is no longer passive considering the necessary communication links between the sites. On the other hand, single-site localisation methods basically overcome these difficulties eliminating the need for inter-site communications. In this study, a single-site localisation method is presented and analysed. This method is applicable to scenarios with a large...
A Disambiguation technique for passive localization using trajectory analysis
, Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 55, Issue 2 , 2019 , Pages 820-829 ; 00189251 (ISSN) ; Behnia, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
In some well-known passive localization methods, when the number of equations equals the number of unknown object coordinates, there arise finite number of possible solutions. A localization disambiguation technique is required to identify the correct solution in these cases. As an example, the exact solution of time-difference-of-arrival (TDOA) based equations for four receiver sites, leads to a couple of solutions with only one of them being the true target position. This ambiguity conventionally is resolved by using angle-of-arrival measurements or using an additional receiver site, which increase the cost and complexity of the system. In this paper, a localization disambiguation...
Synthesis of Colloidal Silver Nanoparticles by Microwave Method and Study of its Antibacterial Activity
, M.Sc. Thesis Sharif University of Technology ; Dolati, Abolghasem (Supervisor)
Abstract
Silver nanoparticles are widely used in different industries because of their antibacterial effects. Many synthesis methods were used to obtain silver nanoparticles. In this study the microwave method is used to synthesize nanosilver. This method is easier and faster in comparison to other methods. The effect of precursors’ concentrations, using different solvents, different remaining time in microwave and microwave power were studied. By increasing the reaction time, microwave power and using different solvents, nanosilver particle size varies from 2 nm up to 300nm. The TEM images, size distribution, XRD patterns and UV-visible spectrum are shown. The obtained nanosilver was used to observe...
Integrated Control and Estimation of Satellite Attitude using Adaptive Nero-Fuzzy Inference System
, M.Sc. Thesis Sharif University of Technology ; Assadian, Nima (Supervisor)
Abstract
This paper presents an integrated attitude control and estimation of satellite by using adaptive neural fuzzy (ANFIS) logic, indeed a system which using ANFIS controller and estimator is considered then an ANFIS simulator that can control and estimate contemporary is supposed. ANFIS system has been trained by using data obtained from an optimal PID controller. Then ANFIS controller performance has been compared with the performance of a PID controller, the analogy has repeated in different situations such as noise and uncertainty. Results show that system with ANFIS controller is more optimal than PID’s in all these situations. After that ANFIS estimator is studied and results indicate the...
Sliding mode control application to amplitude control of comb-actuated resonant microscanners
, Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 5 , 2010 , Pages 633-638 ; 9780791849194 (ISBN) ; Vossoughi, G ; Sharif University of Technology
2010
Abstract
MOEMS (Micro-Opto-Electro-Mechanical System) are MEMS in which the optical part plays a dominant role. The use of MOEMS as scanners and projectors has been studied lately. For high speed scanning applications, electrostatic comb drive actuation has several advantages. In this paper, we demonstrate the application of sliding mode control scheme for amplitude control of comb-actuated resonant microscanners. This method that leads to a simple and practical control function is simply extendable for microscanners with other type of actuation and even for any kind of oscillators that need amplitude control. The functionality and performance of the presented scheme is verified using numerical
Sparsity-based MIMO radars
, Article Applied and Numerical Harmonic Analysis ; 2021 , Pages 323-342 ; 22965009 (ISSN) ; Marvasti, F ; Sharif University of Technology
Birkhauser
2021
Abstract
With advances in technology, Multiple-Input Multiple-Output (MIMO) radars have attracted a lot of attention in different modern military and civilian applications. As there are multiple receivers in a MIMO radar system, the cost can significantly be reduced if we can reduce the sampling rate and send fewer samples to the common processing center. Sometimes, the problem is not even the cost. It is the technology issues of high sampling rates such as the necessity of high-rate Analog-to-Digital (A/D) converters. The reduction in sampling rate can be achieved using Compressive Sensing (CS) or, in a much simpler form, Random Sampling (RS). In CS, we take a number of linear combinations of sparse...
Sparsity-Based MIMO radars
, Article Applied and Numerical Harmonic Analysis ; 2021 , Pages 323-342 ; 22965009 (ISSN) ; Marvasti, F ; Sharif University of Technology
Birkhauser
2021
Abstract
With advances in technology, Multiple-Input Multiple-Output (MIMO) radars have attracted a lot of attention in different modern military and civilian applications. As there are multiple receivers in a MIMO radar system, the cost can significantly be reduced if we can reduce the sampling rate and send fewer samples to the common processing center. Sometimes, the problem is not even the cost. It is the technology issues of high sampling rates such as the necessity of high-rate Analog-to-Digital (A/D) converters. The reduction in sampling rate can be achieved using Compressive Sensing (CS) or, in a much simpler form, Random Sampling (RS). In CS, we take a number of linear combinations of sparse...
The Simultaneous Berth and Quay Crane Scheduling
, M.Sc. Thesis Sharif University of Technology ; Salmasi, Naser (Supervisor)
Abstract
This study addresses the simultaneous berth and quay crane (QC) scheduling problem in a container terminal. The berths are considered as a continuous area and the vessels arrive dynamically. QCs are allowed to move to other vessels before completing the process on an assigned vessel.The objective function is determined based on the practical applications of the problem. It deals with minimization of sum of the completion time of vessels. In this research, a mathematical model has been developed for the research problem. According to NP-hardness of the research problem, two meta heuristic algorithms based on Tabu Search are proposed. To solve the problem, these methods have two layers with...
Developing the MIDA Method for Mid-Rise Structures with Non-symmetrical Plan
, M.Sc. Thesis Sharif University of Technology ; Mofid, Masood (Supervisor)
Abstract
Performance based design becomes an effective method for estimating seismic demands of buildings. Incremental dynamic analysis (IDA) based on a nonlinear response time history analysis (NL-RHA) is considered to be the most accurate method in seismic demand calculations. However, modal incremental dynamic analysis (MIDA), based on the equivalent single degree-of-freedom (SDF) oscillator, is also often used in studying structural engineering performances. The MIDA procedure for estimating seismic demands is extended to unsymmetric-plan buildings. In the MIDA procedure, the seismic demand due to individual terms in the modal expansion of the effective earthquake forces is determined by...
A compact MW-Class short pulse generator
, Article IEEE Transactions on Plasma Science ; Volume 46, Issue 6 , 2018 , Pages 2059-2063 ; 00933813 (ISSN) ; Hashemi, M. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
A megawatt-range short pulse generator based on the diode step recovery phenomenon and the Marx generator idea is presented. This generator utilizes both opening and closing switches in one circuit. The proposed circuit is compact, light, and low cost and is driven by a low-power source. By using a three-stage Marx generator, the output peak power of 0.6 MW was obtained. The dimensions of the generator are 8 cm $ imes8$ cm. Experimental measurements of the output pulse characteristics showed a rise time of 100 ns for a 16- $Omega $ load. The input peak power was 4 W which showed more than 105 times increase in the pulse peak power. © 1973-2012 IEEE
Synthesis and Study of Photocatalytic Properties of g-C3N4/TiO2 Nanocomposite
, M.Sc. Thesis Sharif University of Technology ; Sadrnezhaad, Khatiboleslam (Supervisor)
Abstract
In this research, synthesis and characterization of photocatalytic properties of g-C3N4 / TiO2 nanocomposite was carried out. The target of research was to increase the photocatalytic properties of g-C3N4. So at first, g-C3N4 was synthesized from melamine precursor via thermal pyrolysis. Then, TiO2 nanoparticles were synthesized via sol – gel method. g-C3N4 / TiO2 nanocomposite with heterojunction structure was synthesized in one step by thermal pyrolysis of certain amounts of melamine precursor and TiO2 nanoparticles mixture in 550 ℃. Characterization of synthesized samples was carried out by XRD, FT-IR, UV-Vis, PL, BET, DLS and FE-SEM tests. Characterization results showed that g-C3N4,...
Spread-space holographic CDMA technique: Basic analysis and applications
, Article IEEE Transactions on Wireless Communications ; Volume 1, Issue 2 , 2002 , Pages 311-321 ; 15361276 (ISSN) ; Salehi, J. A ; Sharif University of Technology
2002
Abstract
In this paper, we analyze the basic principles of the spread-space holographic code division multiple access (CDMA) technique. We describe the structure of the encoder and decoder and present a basic mathematical analysis based on spatial harmonic decomposition for the receiver's processing module, which is comprised of a Fourier transform lens and a holographic matched filter. Subsequently, we study two applications of optical holographic CDMA, namely, free-space holographic CDMA photonic switch and free-space (wireless) multiaccess optical (infrared) indoor communications. For both techniques, we describe the two-dimensional imaging techniques, namely user's code transmission, and...
Indoors wireless infrared communications based on spread-space holographic CDMA
, Article 11th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC 2000), London, 18 September 2000 through 21 September 2000 ; Volume 2 , 2000 , Pages 944-948 ; Salehi, J. A ; Sharif University of Technology
2000
Abstract
In this paper we study an application of optical Holographic CDMA for free-space (wireless) optical (infrared) indoor communications. First, we describe the principles of the spread-space Holographic CDMA indicating the structure of the encoder and decoder and describe mathematically the receiver's processing module which is comprised of a Fourier transform lens and a holographic matched-filter. Then, we study the performance of an indoors infrared communication link using spot-diffused configuration. Free-space optical Holographic CDMA processing gain (PG) can in principle be as high as 106-108 and each user can have different modulating signals (Analog or Digital), or different information...
Endurance wave analysis (EWA) and its application for assessment of offshore structures under extreme waves
, Article Applied Ocean Research ; Volume 37 , 2012 , Pages 98-110 ; 01411187 (ISSN) ; Matin Nikoo, H ; Estekanchi, H ; Sharif University of Technology
2012
Abstract
The aim of this paper is to introduce a novel approach, called Endurance Wave Analysis (EWA), for non-linear dynamic analysis and assessment of offshore structures subjected to irregular wave forces. This is, in fact, an extension of the Endurance Time Analysis (ETA) already presented by previous researchers for the seismic assessment of onshore structures. With the EWA method, the offshore structure is simulated under a predefined Intensifying Wave Train Function (IWTF), corresponding to a gradually deteriorating sea state at a specific site. The function is designed so that the roughness of the sea state represented by them increases over the time and even goes well beyond the design sea...
High-power nanosecond pulse generator with high-voltage srd and gdt switch
, Article IEEE Transactions on Plasma Science ; Volume 43, Issue 9 , April , 2015 , Pages 3268-3276 ; 00933813 (ISSN) ; Hashemi, S. M. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
A high-power short-pulse generator based on the dual action of two coupled diodes, a high-voltage step recovery diode and a high-current diode, is presented. This is made possible using a gas discharge tube. Both analysis and SPICE simulation show about 20-dB peak power increment. This gives a high output power level of 5.7 MW with 1-ns pulsewidth and 450-kHz repetition rate obtained from an input average power of 7.1 kW. An efficiency of about 73% is obtained with more than 30 dB increase in the average power delivered to a 50-Ω load
A compact all-solid-state self-compressing low-to-high power converting rF pulse generator
, Article IEEE Transactions on Plasma Science ; Volume PP, Issue 99 , 2016 ; 00933813 (ISSN) ; Hashemi, S. M. A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
In this paper, a novel method for high-repetition-rate high-power radio frequency (RF) pulse generation, which involves only passive solid-state devices and is capable of being used for generating high power microwaves using a low-to-high power converting scheme based on nonlinear self-compression is proposed. The method is also expected to be of low jitter. In the proposed circuit, two high voltage diodes with proper reverse recovery characteristics are used. The simulation results show that the proposed circuit generates RF pulses, with central frequencies up to gigahertz range. By applying a sub-kilowatt power supply, the maximum output power was well over 10 kW. This power can be...
New soliton solution of a varactor-loaded nonlinear transmission line
, Article IEEE Transactions on Microwave Theory and Techniques ; Volume 65, Issue 11 , 2017 , Pages 4084-4092 ; 00189480 (ISSN) ; Ali Hashemi, S. M ; Sharif University of Technology
2017
Abstract
The nonlinearity of a nonlinear transmission line (NLTL) may have a variety of forms. The Korteweg-de Vries (KdV) equation is the governing equation of a highly specific category of NLTLs having a C - V characteristic as C(V) = C0 (1-bV), but works as an approximate model in a general NLTL having any other kinds of nonlinearities. Here, the soliton response of a varactor-loaded NLTL is studied analytically. The presented analysis gives the exact nonlinear partial differential equation (PDE) governing these networks. It is shown that the obtained PDE, being different from the KdV equation, has soliton solutions showing the well-known properties of the KdV solitons. These obtained solitons...
Analysis of the power transfer to a nonlinear transmission line
, Article IEEE Transactions on Microwave Theory and Techniques ; Volume 65, Issue 11 , 2017 , Pages 4073-4083 ; 00189480 (ISSN) ; Hashemi, S. M. A ; Sharif University of Technology
2017
Abstract
The input current of a nonlinear transmission line (NLTL), driven by a step voltage pulse, was analyzed theoretically. As specific results of the analysis, two basic parameters of NLTLs were formulated for the first time: the energy injected to NLTLs and their characteristic impedance. The energy delivered to an NLTL by a square voltage source, with a series resistance of RS, is given by a closed-form formula, which depends on the NLTL parameters and the input pulse characteristics. Considering the importance of the problem of the determining the injected energy content in a wide variety of the different applications of NLTLs, the obtained result will be of great importance, facilitating the...