Loading...
Search for:
abedi--masoumeh
0.119 seconds
Total 148 records
Interference Reduction and Cancellation by Beamforming in Cognitive Radios
, M.Sc. Thesis Sharif University of Technology ; Nasiri Kenari, Masoumeh (Supervisor)
Abstract
Cognitive Radio (CR), as a new concept to efficiently utilize a licensed spectrum, and this has received intensive attension in recent years. By applying the cognitive technique, an unlicensed user (the secondary user (SU)) is allowed to transmit at the Primary User’s (PU) spectrum band under some conditions. Different approaches have been introduced to be utilized by the SU in order to be able to efficiently transmit at the PR’s spectrum without any sustainsial destructive effects on PR transmission and reception, which one of them is using multiple antenna in the cognitive transmitter. Hereby, CR is able to increase its throughput without substansial harmfull effect on PR’ transmission by...
, M.Sc. Thesis Sharif University of Technology ; Nasiri Kenari, Masoumeh (Supervisor)
Abstract
In the recent years, the cooperative communications based on Network Coding have received significant attentions to simultaneously improve the diversity order and the network throughput. In this thesis, a new cooperative transmission scheme for the cooperative relay-based networks called “Convolutional Network-Coded Cooperation” (CNCC) is proposed, in which a systematic convolutional code is used in the network level. In this scheme, the systematic packets are directly transmitted by the sources, and the parity packets, calculated based on the received sources’ packets, are transmitted by the relays. The proposed CNCC scheme is considered in the cooperative networks including N sources, M...
Preparation and Investigation of the Electrochemical Behavior of Sensors Based on Glassy Carbon Electrode Modified with Various Carbon Nanostructures Decorated by Some of Metal Nanoparticlesfor Determination of Ceftizoxime
, M.Sc. Thesis Sharif University of Technology ; Shahrokhian, Saeed (Supervisor) ; Masoumeh Ghalkhani (Co-Advisor)
Abstract
In the recent years, sensors and biosensors attracts much attentions as a suitable devices in analytical chemistry. In this meantime carbon nanostructures and metal nanoparticles act as a good choice owing to their unique properties such as high electrical conductivity andmechanical and chemical stability in modification of the surface of sensors and biosensors. Because of importance of analysis the trace amounts of pharmaceutical and biological compounds, in this studies the surface of glassy carbon electrode was modified with some carbon nanostructures and metal nanoparticles for electrochemical investigation and determination of pharmaceutical and clinical compounds.In the first work, a...
Multiple-Access Schemes in Molecular Communication Networks and Performance Analysis
, M.Sc. Thesis Sharif University of Technology ; Nasiri Kenari, Masoumeh (Supervisor)
Abstract
Molecular communication (MC), which has stimulated a great deal of interest in recent years, is a new paradigm for communication among nanoscale biological machines. In MC, molecules are carriers of information and information is encoded into concentration, type or releasing time of molecules. One of the issues in MC is to consider a network consisting of multiple nano-sensors or living cells, which intend to communicate with each other.In this thesis, we first consider multiple-access networks in MC. In multiple-access networks, multiple sender nano-machines intend to communicate with a receiver nano-machine through a common medium. We consider the receiver with ligandreceptors and...
Modeling and Analysis of Stochastic Clustered Networks
, Ph.D. Dissertation Sharif University of Technology ; Nasiri Kenari, Masoumeh (Supervisor)
Abstract
Wireless communication networks are undergoing a significant transformation from coverage-driven deployment of macrocells to user-centric and cluster-based capacity-driven deployments of low-power base stations (BSs), usually at the locations of high user density. On the other hand, the increasing irregularity and randomness in the locations of nodes has led to an increased interest in the use of random spatial models along with tools from stochastic geometry and point process theory for their accurate modeling and tractable analysis. To this end, this thesis investigates clustered networks for different wireless applications. In this regards, comprehensive and tractable analytic frameworks...
Interfacial instabilities in sediment suspension flows
, Article Journal of Fluid Mechanics ; Vol. 758, issue , November , 2014 , p. 312-326 ; Jalali, M. A ; Maleki, M ; Sharif University of Technology
2014
Abstract
We report the existence of interfacial instability in the two-dimensional channel flow of a sediment suspension whose particles diffuse in the carrier fluid due to shear-induced collisions. We derive partial differential equations that govern the deformations of the interface between the sediment suspension and the clear fluid, and devise a perturbation method that preserves the positivity of the particle volume fraction. We solve perturbed momentum, particle transport and deforming interface equations to show that a Kelvin-Helmholtz-type unstable wave develops at the interface for wavelengths longer than a critical value. Short-wavelength oscillations of the interface are damped due to...
Estimation of demand function for natural gas in Iran: Evidences based on smooth transition regression models
, Article Economic Modelling ; Vol. 36, issue , 2014 , pp. 341-347 ; Abbasspour, M ; Abedi, Z ; Sharif University of Technology
2014
Abstract
This paper attempts to study the demand function of natural gas in Iran using smooth transition regression model (STR). To this end, gross domestic productions (GDP), real price of natural gas and temperature have been employed as variables explaining the natural gas demand from 1971 to 2009. The results indicate that natural gas demand follows an LSTR1 nonlinear two-regime model if the real price of natural gas is considered as the transition variable. Estimation results also indicate that the slope parameter approximately equals the high value of 10 and the threshold value is 31.82. Rials. 111 USD=24,700 Rials (IRR) at April 2013. per one cubic meter consumption of natural gas. The results...
Integration of CFD and Nelder-Mead algorithm for optimization of MOCVD process in an atmospheric pressure vertical rotating disk reactor
, Article International Communications in Heat and Mass Transfer ; Volume 43 , April , 2013 , Pages 138-145 ; 07351933 (ISSN) ; Farhadi, F ; Boozarjomehry, R. B ; Sharif University of Technology
2013
Abstract
In this work, optimization of metalorganic chemical vapor deposition process for uniform layer thickness with especial attention to reactor geometric parameters as decision variables is presented. A numerical solution to a steady thermal flow associated with multi-species and chemical reactions in atmospheric pressure axisymmetrical rotating disk reactor by the CFD technique is obtained. Such a simulation is conducted on the assumption that the low Mach number flow is laminar. Then the validation of the numerical results with the benchmark solutions is conducted. Finally, integrating the CFD simulator with an optimization program, based on the Nelder-Mead algorithm, as a new approach is...
Control of lumbar spine flexion-extension movement by PD controller and feedback linearization method
, Article ICCAS 2010 - International Conference on Control, Automation and Systems, 27 October 2010 through 30 October 2010 ; 2010 , Pages 2024-2029 ; 9781424474530 (ISBN) ; Vossughi, G. R ; Parnianpour, M ; Sharif University of Technology
2010
Abstract
The role of motor control in development of low back pain is subject of many researches both in theoretical and experimental fields. In this work flexion-extension movement of lumbar spine have been controlled by three different methods, including feedback linearization (FBL), PD control and their combinations. The model involves 7 links: 1 link for pelvis, 5 links for lumbar vertebrae and 1 link for trunk. Torque actuators have been used on each joint to make them follow desired trajectory. In linear control method, equations of motion have been linearized with respect to upright position and then control signals have been applied in the direction of eigenvectors. Robustness of each method...
Effect of finishing temperature on mechanical properties of a Nb-microalloyed steel sheet
, Article Advanced Materials Research, 17 September 2010 through 19 September 2010 ; Volume 129-131 , 2010 , Pages 1022-1028 ; 10226680 (ISSN) ; 9780878492435 (ISBN) ; Akbarzadeh, A ; Abedi, A ; Sharif University of Technology
2010
Abstract
Thermo mechanical processing and controlled rolling of microalloyed steel sheets are affected by several factors. In this investigation, finishing temperature of rolling which is considered as the most effective parameters on the final mechanical properties of hot rolled products has been studied. For this purpose, three different finishing temperatures of 950, 900 and 850 °C below the non-recrystallization temperature and one temperature of 800 °C in the intercritical range were chosen. It is observed that decreasing the finishing temperature causes increase of strength and decrease of total elongation. This is accompanied by more grain refinement of microstructure and the morphology was...
MapReduce service provisioning for frequent big data jobs on clouds considering data transfers
, Article Computers and Electrical Engineering ; Volume 71 , 2018 , Pages 594-610 ; 00457906 (ISSN) ; Goudarzi, M ; Abedi, S ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Many companies regularly run Big Data analysis, and need to optimize their resource usage considering cost, deadline, and environmental impact simultaneously. The cloud allows choosing from various virtual machines (VM) where the number and type of VMs affect the outcome such as the time for data placement and data shuffle phases, a task's energy consumption and execution time, and the makespan of jobs. We provide provisioning and scheduling algorithms to minimize environmental impact, considering the above factors, for frequently executed MapReduce jobs. To mathematically model the problem and obtain the optimal solution, we present an Integer Linear Programming (ILP) model and then...
Numerical simulation of inlet buzz
, Article Aerospace Science and Technology ; Volume 97 , 2020 ; Askari, R ; Soltani, M. R ; Sharif University of Technology
Elsevier Masson SAS
2020
Abstract
Comprehensive numerical analyses are conducted to simulate and capture “Buzz” phenomenon in a supersonic mixed compression air inlet. The buzz is an unsteady self-sustained feature that occurs in supersonic inlets, especially when operating in their subcritical condition. In such a situation, the shock waves oscillate along the inlet and cause mass flow fluctuations inside the inlet that will deteriorate the engine performance significantly. An axisymmetric unsteady numerical simulation was used to solve the Navier–Stokes equations combined with the URANS SST k–ω turbulence model. The simulations for two different free-stream Mach numbers of M∞=2.0 and 2.2 and at two specific subcritical...
Performance and Analytical Discussion on OFDMA-Based Cognitive Radio Networks with Relaying Capabilities
, M.Sc. Thesis Sharif University of Technology ; Nasiri Kenar, Masoumeh (Supervisor)
Abstract
In this thesis, a novel OFDMA-based cognitive cooperative relaying scheme is proposed in which cognitive users not only try not to interfere with primary users but also assist them by relaying their information. Both primary users (PU) and cognitive users (CR) communicate to a common base station (BS). Bit error probability (BEP) of primary users and outage probability of primary users are investigated to evaluate performance of the primary users. In all parts of this thesis, we assume that data of users is not jointly encoded across subcarriers. So, the outage probability and BEP are investigated for each subcarrier independently. In the last part of the thesis, it is assumed that data is...
Modeling and Analysis of Two Wireless Networks with Opportunistic and Primary Spectrum Access
, M.Sc. Thesis Sharif University of Technology ; Ashtiani, Farid (Supervisor) ; Nasiri Kenari, Masoumeh (Supervisor)
Abstract
In this thesis, we propose an analytical model to evaluate the maximum stable throughput of a cognitive IEEE 802.11-based WLAN overlaid on a cellular network. In the considered scenario, the secondary nodes operate in uplink frequency band of primary network and transmit on their own idle detected primary channels using OFDM technique. The activity of primary nodes is modeled independently by ON-OFF alternating states with negative exponential distributed durations. The main feature of the proposed analytical model is to include different status of the secondary users, i.e., different spectrum opportunities for different cognitive users, as the result of dynamic nature of primary users as...
Information-Theoretic Analysis of Coognitive Radio Networks
, Ph.D. Dissertation Sharif University of Technology ; Hashemi, Homayoun (Supervisor) ; Nasiri Kenari, Masoumeh (Supervisor)
Abstract
In this thesis, the effect of cognition in wireless networks is studied. In a wireless communica-tion network, cognition is the ability of a device to sense the transmissions of neighboring nodes and adapt its own transmission to the sensed environment. Cognitive radios are very attractive be-cause of the increasing need for more efficient use of frequency spectrum. The goal of this thesis is the analysis of cognitive radio networks from an information theoretic perspective and to this end statistical models of the wireless medium with a limited and tractable number of devices are uti-lized. We consider three different models in three parts of the thesis. First, we consider a new...
Opportunistic RF Energy Harvesting in Cognitive Radio Networks
, M.Sc. Thesis Sharif University of Technology ; Nasiri-kenari, Masoumeh (Supervisor) ; Ashtiani, Farid (Supervisor)
Abstract
Considering energy efficiency ways a key role in designing future wireless networks( 5G mobile networks). Moreover Spectrum efficiency is another critical issues in designing wireless networks. Cognitive radios can improve the spectrum efficiency. On the other hand, radio frequency (RF) energy harvesting has emerged as a promising technique to supply energy for wireless networks and thereby increase their energy efficiency. In this thesis, we propose a new technique for the RF-powered CRNs.To this end,We consider a cognitive radio network comprised of a primary user and a secondary user. The primary user, uses a typical frequency band for transmit data in a time slot basis and both the...
Information theoretic Analysis of Joint Time and Concnetration Modulation for Molecular Communications
, M.Sc. Thesis Sharif University of Technology ; Nasiri Kenrai, Masoumeh (Supervisor) ; Mirmohseni, Mahtab (Co-Supervisor)
Abstract
Today communication systems use electromagnetic signals for data transmission. However there are applications, in which the use of these signals is impossible or inefficient. For example in underwater communication, because of salinity of water, electromagnetic signals attenuate very fast. Regarding to this, inspired by nature, molecular communication systems is introduced, which use molecules as carriers of information for transmission of data. One of the main challenges in molecular communication in diffusion medium is that most of these channels suffer from low information capacity. With this respect, this thesis studies the channel capacity of diffusion based molecular channels by...
Analysis of Resource Allocation Methods in Massive MIMO Systems using Game Theory
, M.Sc. Thesis Sharif University of Technology ; Behrouzi, Hamid (Supervisor) ; Nasiri Kenari, Masoumeh (Co-Supervisor)
Abstract
Nowadays increasing demands of Bandwidth, higher data rate and efficiency cause a huge and novel challenges in communicational systems. One of the recent innovative idea to satisfy these increasing demands is Heterogeneous Networks. Compressive deployment of small cell in Heterogeneous Networks can fulfill a large number of satisfactory parameters in wireless networks. After first Presentation of Heterogeneous Networks idea, loads of structure based on them was proposed.In this Research we consider two outstanding and common structure for this technology and analyze the user association and resource allocation problem at their specific structure. The first one is equipped with simple...
Zero-error Coding Based ISI Mitigation for Molecular Communication Systems
, M.Sc. Thesis Sharif University of Technology ; Nasiri Kenari, Masoumeh (Supervisor) ; Mirmohseni, Mahtab (Supervisor)
Abstract
Molecular communication which is inspired by nature has emerged as a promising field in recent years for its potential applications in medicine, environment, tissue engineering, industry and so on. In molecular communication, molecules are the information carriers. One of the mechanisms of movement of molecules that does not require any infrastructure is Diffusion. Diffusion-based molecular communication in which molecules diffuse in the medium in order to reach the receiver, has two major problems: delayed and lost molecules. Due to the randomness of diffusion, molecules are usually received with varied delays, their order of reception is different from the order of transmission and even...
Improving the Performance of Non-Volatile Memory based CNN Accelerators
, Ph.D. Dissertation Sharif University of Technology ; Hessabi, Shaahin (Supervisor) ; Bagherzadeh, Nader (Co-Supervisor)
Abstract
Today convolutional neural networks (CNN) are very popular due to their high accuracy and robustness. As the size and complexity of CNNs grow, the demand for larger on-chip memories also increases. Given that off-chip access memory has a high cost, one solution is to enlarge on-chip caches by employing emerging multi-level Cell (MLC) STT-RAMs. This memory provides higher capacity at the cost of lower reliability. The root cause of low reliability of MLC STT-RAM is failure of read and write operations. However, MLC STT-RAM and CNNs are perfect matches in the sense that in one hand MLC STT-RAM provides higher capacity, on the other hand CNN can tolerates moderate level of inaccuracy and low...