Multiuser power allocation in downlink of cooperative CDMA networks

, Article IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC, 13 September 2009 through 16 September 2009 ; 2009 ; 9781424451234 (ISBN) Abdizadeh, M. T ; Jafarnia, A ; Sharif University of Technology

2009

Abstract

In this paper, we study the downlink of cooperative Direct-Sequence Code Division Multiple Access (DS-CDMA) systems, where a set of Mobile Terminals (MT) cooperate with the purpose of improving their downlink communications reliability with the Base Station (BS). For combating Multiple-Access Interference (MAI) as well as transferring complexity and spatial processing from the mobile terminals to the transmitter of BS, multiuser transmitter precoding is considered. In addition to multiuser precoding based on Minimum Mean-Square Error (MMSE) criterion for mitigating MAI, the proper transmission power control strategy under a fixed total power constraint is proposed and analyzed. Compared with...

Mathematical analysis of optimal tracking interval management for power efficient target tracking wireless sensor networks

, Article Iranian Journal of Electrical and Electronic Engineering ; Volume 8, Issue 3 , 2012 , Pages 195-205 ; 17352827 (ISSN) Jamali-Rad, H ; Abolhassani, B ; Abdizadeh, M ; Sharif University of Technology

2012

Abstract

We study the problem of power efficient tracking interval management for distributed target tracking wireless sensor networks (WSNs). We first analyze the performance of a distributed target tracking network with one moving object, using a quantitative mathematical analysis. We show that previously proposed algorithms are efficient only for constant average velocity objects; however, they do not ensure an optimal performance for moving objects with acceleration. Towards an optimal performance, first, we derive a closed-form mathematical expression for the estimation of the minimal achievable power consumption by an optimal adaptive tracking interval management algorithm. This can be used as...

Joint optimization of power allocation and relay deployment in wireless sensor networks

, Article IEEE Wireless Communications and Networking Conference, WCNC, 18 April 2010 through 21 April 2010 ; April , 2010 ; 15253511 (ISSN) ; 9781424463985 (ISBN) Abdizadeh, M ; Rad, H. J ; Abolhassani, B ; Sharif University of Technology

2010

Abstract

We study the problem of optimizing the symbol error probability (SEP) performance of cluster-based cooperative wireless sensor networks (WSNs). It is shown in the literature that an efficient relay selection protocol based on simple geographical information of the nodes to execute the cooperative diversity transmission, can significantly improve the SEP performance at the destination of such networks. Also, a similar analysis on the optimal power allocation for the source and the relay exists in the literature. However, we propose that to achieve the minimum SEP at the destination, a joint optimization of power allocation and relay selection should be accomplished. To this aim, we...

An energy efficient target tracking scheme for distributed wireless sensor networks

, Article Proceedings of the 2009 6th International Symposium on Wireless Communication Systems, ISWCS'09, 7 September through 10 September ; 2009 , Pages 136-140 ; 9781424435845 (ISBN) Jamali Rad, H ; Abolhassani, B ; Abdizadeh, M ; Sharif University of Technology

2009

Abstract

We study the problem of power optimization for object tracking using distributed Wireless Sensor Networks (WSNs). The accuracy of the object tracking is dependent on the tracking time interval. Smaller tracking time interval increases the accuracy of tracking a moving object. However, this increases the power consumption significantly. This paper proposes a modified adaptive sleep time management scheme called Modified Predict and Mesh (MPaM) to adapt tracking time interval such that it minimizes power consumption while keeping an acceptable tracking accuracy. Also a quantitative analysis to compare the performances of the conventional PaM and proposed Modified PaM (MPaM) schemes is...

Towards the optimal tracking interval management for target tracking wireless sensor networks

, Article ATC 2009 - Proceedings of the 2009 International Conference on Advanced Technologies for Communications, 12 October 2009 through 14 October 2009 ; 2009 , Pages 161-166 ; 9781424451395 (ISBN) Jamali Rad, H ; Abolhassani, B ; Abdizadeh, M ; Sharif University of Technology

2009

Abstract

We consider the minimization of power consumption in target tracking wireless sensor networks (WSNs) using dynamic modification of tracking interval. In this context, we first analyze the performance of such networks, using a quantitative mathematical analysis. Then we calculate an upper bound for the achievable improvement in total power consumption, when using an adaptive time interval modification algorithm for tracking moving objects with acceleration. Towards this optimum functionality, we propose a novel adaptive algorithm (AHC) to adapt the tracking interval such that it minimizes power consumption while keeping an acceptable accuracy. Simulation results show that using the proposed...

Multiuser precoding and power allocation in downlink of cooperative CDMA networks

, Article ATC 2009 - Proceedings of the 2009 International Conference on Advanced Technologies for Communications, 12 October 2009 through 14 October 2009, Hai Phong ; 2009 , Pages 279-283 ; 9781424451395 (ISBN) Abdizadeh, M ; Jafarnia, A ; Jamali Rad, H ; Sharif University of Technology

2009

Abstract

In this paper, we study the downlink of cooperative Direct-Sequence Code Division Multiple Access (DS-CDMA) systems, where a set of Mobile Terminals (MT) cooperate with the purpose of improving their downlink communications reliability with Base Station (BS). For combating Multiple-Access Interference (MAI) as well as transferring complexity and spatial processing from the mobile terminals to the transmitter of BS, multiuser transmitter precoding is considered. In addition to multiuser precoding based on Minimum Mean-Square Error (MMSE) criterion for mitigating MAI, the proper transmission power control strategy under a fixed total power constraint is proposed and analyzed. Compared with...

Cooperative communication with power allocation in downlink CDMA networks

, Article ATC 2009 - Proceedings of the 2009 International Conference on Advanced Technologies for Communications, 12 October 2009 through 14 October 2009, Hai Phong ; 2009 , Pages 284-288 ; 9781424451395 (ISBN) Abdizadeh, M ; Rad, H. J ; Jafarnia, A ; Sharif University of Technology

2009

Abstract

In this paper, we study the downlink of cooperative Direct-Sequence Code Division Multiple Access (DS-CDMA), where a set of Mobile Terminals (MT) are cooperating with the purpose of improving their downlink communications reliability with the Base Station (BS). In order to achieve the spatial diversity, a new cooperation scenario is proposed. Afterward, in addition to multiuser precoding, Maximum Ratio Combining (MRC) according to the Maximum Signal to Noise Ratio (MSNR) criterion at the destination is investigated. Then, the optimal transmission power control strategy under a fixed total power constraint is illustrated and analyzed. Compared with equal transmission power assignment where BS...

A new adaptive prediction-based tracking scheme for wireless sensor networks

, Article Proceedings of the 7th Annual Communication Networks and Services Research Conference, CNSR 2009, 11 May 2009 through 13 May 2009, Moncton, NB ; 2009 , Pages 335-341 ; 9780769536491 (ISBN) Jamali Rad, H ; Abolhassani, B ; Abdizadeh, M. T ; Sharif University of Technology

2009

Abstract

The accuracy of the object tracking is dependent on the tracking time interval. Smaller tracking time interval increases the accuracy of tracking a moving object. However, this increases the power consumption significantly. This paper proposes a new adaptive algorithm (AEC) to adapt tracking time interval such that it minimizes power consumption while keeping the required accuracy. Simulation results show that using the proposed algorithm, the tracking network has a good performance with the added advantage of reducing the power consumption significantly when compared with existing nonadaptive methods (like PATES). Moreover, simulation results show that the performance of the proposed...

The effects of nano Mgo on physical and mechanical properties of Al 2O3-SiC composites

, Article Journal of Ceramic Science and Technology ; Volume 3, Issue 1 , 2012 , Pages 29-34 ; 21909385 (ISSN) Nemati, A ; Surani, F ; Abdizadeh, H ; Baharvandi, H. R ; Sharif University of Technology

2012

Abstract

In this research, the effects of nano-sized MgO in Al2O 3-SiC composites were investigated. The overall changes in the density and mechanical properties of sintered samples (hardness, bending strength and toughness) were evaluated. After mixing, drying and uniaxial compaction of the powders, they were first heat-treated at low temperature in an electric furnace to remove any residuals. They were then heat-treated at high temperature (1700 °C) inside a graphite furnace in argon atmosphere for sintering (at normal and high pressure). The content of MgO in the Al 2O3-10 vol% SiC composite was 0, 500, 1000, and 1500 ppm. Thefracture toughness(KIC)of sintered composite with 10...

Anti-solvent-free Deposition of Perovskite Layers for Fabricating Module Scale Solar Cells

, M.Sc. Thesis Sharif University of Technology Abdizadeh, Karim (Author) ; Nemati, Ali (Supervisor) ; Taghavinia, Nima (Supervisor)

Abstract

Perovskite solar cells with 25.5% efficiency and fast and cheap manufacturing process are among the most promising technologies in this field to replace silicon cells. Despite the challenges of stability and toxicity to these cells, their manufacturing technology has recently shifted to the development of large-scale manufacturing methods in module dimensions. In the present study, the fabrication of perovskite cells in large dimensions to achieve the perovskite module has been aimed and studied that to achieve this, the method of large-scale spraying and printing using the vacuum system was used to create cell-forming films and, consequently, to make the final cell and module. To...

Some Innovations in Numerical Simulation of Inviscid Three Dimensional Flow with Moving Boundaries

, Ph.D. Dissertation Sharif University of Technology Ramezani, Ali (Author) ; Mazaheri, Karim (Supervisor)

Abstract

The main subject of this thesis is to improve conventional CFD algorithms applied in numerical simulation of inviscid unsteady flows around moving boundaries with large relative motions, on unstructured grids. All challenges in this regard are reviewed, and appropriate efficient schemes are introduced to address them. A new scheme is presented for valid grid generation during grid movement and is implemented for 2D and 3D problems. Customary three dimensional convergence acceleration techniques such as implicit time stepping and multigriding have been applied. For implicit solution of the flow equations a new algorithm is used. Via a special renumbering algorithm, the approximate...

Development of Parallel Algorithm for Adjoint Optimization of Turbine Blade

, M.Sc. Thesis Sharif University of Technology Salehi, Hadi (Author) ; Mazaheri, Karim (Supervisor)

Abstract

This study develops an aerodynamic shape optimization code using parallel processing capability based on a gradient-based adjoint method. Calculation of the gradient of the objective function with respect to design variables is the most costly part of the gradient-based optimization algorithms. Applying adjoint methods, gradients can be calculated with solving some additional equations known as the "adjoint equations", instead of direct calculation. In this study, the blade shape optimization is performed by inverse design method and using steepest descent optimization algorithm. The objective function of inverse design problem is the desired blade surface pressure distribution. In each...

Acceleration Convergence of New Gradient-based Aerodynamic Optimization Algorithms

, M.Sc. Thesis Sharif University of Technology Taheri, Ramin (Author) ; Mazaheri, Karim (Supervisor)

Abstract

Aerodynamic shape optimization has been always of great importance in aerospace design. Recent advancements in computational algorithms and hardware, has made it feasible to have advanced optimization as a standard part of desing procedure. Here we have promoted aerodynamic optimization in three different applications, i. e., wing-body configuration, hydro propellers, and air propellers. First we have reviewed fluidic theoretical aspects, and have selected appropriate physical models or existing softwares. Accuracy of physical analysis or software is validated. Then different optimization algorithms are reviewed, and schemes used in this thesis are described and the softwares are validated. ...

Steady State and Transient Simulation of Single Spool Turbojet Engine at High Rotational Speeds

, M.Sc. Thesis Sharif University of Technology Mansouri, Hossein (Author) ; Mazaheri, Karim (Supervisor)

Abstract

In this research, steady state and transient performance of a single spool axial turbojet engine (without afterburner) is studied. Performance maps of main components such as; compressor, combustor and turbine are extracted from a similarity (geometry independent) approach.Then using nested loops method, steady state model of the turbojet engine is developed and using shaft dynamics and volume packing equations, transient model of the turbojet engine is analyzed. Steady state and transient simulations results of an engine are validated by experimental data and then effect of changes on input parameters such as; polar moment of inertia, Mach number, fuel heating value, pressure and...

Aerodynamic Optimization of Axial Compressors Using Adjoint Equations

, M.Sc. Thesis Sharif University of Technology Roueeni, Ali (Author) ; Mazaheri, Karim (Supervisor)

Abstract

In this study, aerodynamic shape optimization of axial compressors is considered. In order to optimization, one of the gradient based optimization algorithms, namely Adjoint method, is used. Recently, Adjoint method has been emerged as one of the reliable gradient based optimization algorithms in turbomahineries applications. Because this method is a gradient method of optimization, similar to the other entire gradient based algorithms, adjoint method also has a better convergence than non-gradient based optimization algorithms. In this work, aerodynamic shape optimization of two-dimensional cross section through a transonic axial compressor is studied. The process is considered for midspan...

One Dimensional Simulation of the Internal Flow Field and Design and Optimization of a Solid Fuel Ramjet

, M.Sc. Thesis Sharif University of Technology Enayati, Vahid (Author) ; Mazaheri, Karim (Supervisor)

Abstract

Ramjets have many applications and in the speed range of Mach numbers 2 to 5 show the best performance in terms of specific fuel consumption. In many applications, including some anti-air missiles, cannon and mortars, solid fuel ramjet can be used to improve the system performance.
In this thesis, two activities are performed:
A) One dimensional simulation of the internal flow field of solid fuel ramjet by development of available softwares.
B) Optimization of design parameters of a specific ramjet motor based on the above simulation.
The main target of this thesis is simulation of internal ballistics, design and optimization of a solid fuel ramjet for a particular...

Design and Integration of a Connected Pipe Test Facility for Liquid Fuel Ramjet

, M.Sc. Thesis Sharif University of Technology Tavassoli, Farid (Author) ; Mazaheri, Karim (Supervisor)

Abstract

In the present study, design and manufacturing of a connected pipe liquid fuel ramjet test platform is implemented for performance investigation of a research liquid fuel ramjet burner in the thermodynamic flight conditions. Design and manufacturing of platform systems include: the hot air supply system, the liquid fuel system and the square cross-sectional combustion chamber with the v-gutter shape flame holder. In order to determine the performance range of subsystems, calibration process has been carried out. Calibration process of the hot air supply system includes: determining of the burner inlet velocity and temperature. Also, calibration of the liquid fuel system includes: determining...

Aerodynamic Investigation of an Aeroelastic Flapping Wing and Optimum Design Method

, Ph.D. Dissertation Sharif University of Technology Ebrahimi, Abbas (Author) ; Mazaheri, Karim (Supervisor)

Abstract

Flapping wing vehicles produce aerodynamic lift and thrust through the flapping motion of their wings. The dynamic performance of a flexible membrane flapping wing is experimentally investigated here. To investigate aeroelastic effects of flexible wings (specifically, wing’s twisting stiffness) on hovering and cruising aerodynamic performance, a flapping-wing system and an experimental setup were designed and built. This system measures the unsteady aerodynamic and inertial forces, power usage and angular speed of the flapping wing motion for different flapping frequencies, angles of attack, various wind tunnel velocities up to 12 m/s and for various wings with different chordwise...

Method Developing of National Technology Roadmap for Heavy Turbofan Engine Industry based on Conceptual design

, M.Sc. Thesis Sharif University of Technology Shamekhi, Vahid (Author) ; Mazaheri, Karim (Supervisor)

Abstract

In this thesis, a method developed for producing technology roadmap to identify technologies needed in design, construction and testing of turbofan engines. In the first phase and in scoping step, 10 years’ time horizon is determined. Then project organization and the role required are intended and after that the second phase that is technology roadmap formation is begun. Market identification, product identification by key success factors forms and experts are steps of this phase and determination of three generations of engine are results of product identification step. After that, the technology identification step is begun but simultaneously the technology mapping drawing steps for...

, M.Sc. Thesis Sharif University of Technology Sajadian, Ali (Author) ; Faez, karim (Supervisor)

Abstract

In this thesis all the information about different techniques and methods used in Local Area Network (LAN) are described and organized as follows:
Chapter 1: The network properties are described including Network definitions and different types of LAN and their relative applications
Chapter 2 :Different techniques and protocols of data transfer and switching methods are being described and compared.
Chapter 3 : Network technology consists of different topologies for physical connections and various transfer Medias are covered.
Chapter 4 :All network protocols are described including different methods of DATA access in LOOP, RING and BUS topologies and the ISO and IEEE...