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karrabi--hadi
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Second law based analysis of supplementary firing effects on the Heat Recovery Steam Generator in a combined cycle power plant
, Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 1 , 2010 , Pages 201-209 ; 9780791849156 (ISBN) ; Rasoulipour, S ; Sharif University of Technology
2010
Abstract
The supplementary firing is one of the techniques which are used to increase the output power of the combined cycle power plants (CCPP). The low construction cost per generated power encourages designers to consider it in the new CCPP. In this paper the thermal and exergy analyses of HRSG for various operating conditions in variation of loads and variation of ambient temperature carried out. They are based on the performance test data at different operating conditions. The objective of these analyses is to present the effects of supplementary firing on gross power output, combined cycle efficiency and the exergy loss in Heat Recovery Steam Generator (HRSG) devices at different ambient...
Flow fields investigation and temperature distribution on a rotating disk imposed by a turbulent impinging jet
, Article 2010 14th International Heat Transfer Conference, IHTC 14, 8 August 2010 through 13 August 2010, Washington, DC ; Volume 5 , 2010 , Pages 719-725 ; 9780791849408 (ISBN) ; Rasoulipour, S ; Sharif University of Technology
2010
Abstract
Numerical investigation of fluid flow structure and convective heat transfer due to a circular jet impinging on a rotating disk is performed. Temperature and convection heat transfer coefficient are calculated. Flow is considered to be steady, incompressible and turbulent. k-ε RNG model is used to model the turbulent flow. Results are compared with experimental data showing good agreement. Two new criteria are introduced and used to evaluate the performance of cooling process, the first is maximum temperature difference on the disk, and the second is the average temperature of the disk. The first parameter shows the uniformity of temperature distribution in the disk and the second shows the...
Optimization of A Centrifugal Compressor And Its Validataion With Exprimenatla And Numerical Results
, M.Sc. Thesis Sharif University of Technology ; Hajilouy Benisi, Ali (Supervisor)
Abstract
The actual flow stream through compressor is 3D and fluctuated because of complicated geometry, fluid viscosity and high velocity. Therefore, more accurate analysis of this kind of flow, it is better to use 3D model. Nowadays the flow modeling software are able to model and analysis flow regime using numerical methods in three dimensions. Using these software allow us to find the ways which can reduce the energy losses to improve compressor efficiency.In current work, based on 3D numerical analysis, the flow regime in a centrifugal compressor is investigated and also the sensitivity of this analysis with mesh sizing is explored. The k-e type RNG model is used for modeling turbulent behavior...
Zero D and 3D analysis of the centrifugal compressor of a gas turbine and its evaluation using experimental results
, Article ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011, 11 November 2011 through 17 November 2011 ; Volume 1 , November , 2011 , Pages 897-906 ; 9780791854877 (ISBN) ; Pourfarzaneh, H ; Hajilouy Benisi, A ; Sharif University of Technology
2011
Abstract
In compressor design, it is necessary to simulate the compressor before manufacturing and performing experimental studies. One of the most efficient and common modeling methods is zero D analysis using scaling method with constant coefficients. Although it is efficient in the vicinity of the design point, its results are not acceptable in the off design points due to the growing error by getting away from design points. In this research, a novel zero D analysis method is developed predict accurately the compressor performance not only in the design point but also in the off design pint. In this method, variable coefficients are used instead of constant coefficients, which are obtained based...
Experimental and numerical investigation of a centrifugal compressor
, Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 3 , 2010 , Pages 447-458 ; 9780791849170 (ISBN) ; Hajilouy Benisi, A ; Nili Ahmadabadi, M ; Sharif University of Technology
2010
Abstract
In this research, centrifugal compressor of a gas turbine is investigated experimentally and numerically. Operation line of the compressor as a component of the gas turbine is obtained experimentally by measurements of impeller rotational speed, and flow parameters at the compressor inlet and outlet during the gas turbine operation. The flow field inside the impeller and diffusers are analyzed numerically using a full 3D Navier-Stokes program with SST turbulence model. Boundary conditions for the numerical simulation are specified from the experimental measurements. The operation line of the compressor is obtained numerically, which is compared with that of the experimental results, and...
Boundary drag force acting on an impenetrable nano-particle
, Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 3 , 2010 , Pages 469-473 ; 9780791849170 (ISBN) ; Kebriai, M. H ; Meigounpoury, M. R ; Sharif University of Technology
2010
Abstract
Flow over nano spheres is a fundamental problem encountered in many engineering technical problems and the motion of nano-particles is important in many technical areas, for example nano-organizms motion in aqueous media, super hydrophobic spray for coating materials, nano-capsules for detecting cancer, and additive nano-particles in oil and fuel for automotive engines. In this paper computations are performed to determine the steady flow forces acting on the stationary nano-tube for Reynolds numbers in the range of 0.1
Advances in heuristic signal processing and applications
, Book ; Chatterjee, Amitava ; Nobahari, Hadi ; Siarry, Patrick
Springer
2013
Abstract
There have been significant developments in the design and application of algorithms for both one-dimensional signal processing and multidimensional signal processing, namely image and video processing, with the recent focus changing from a step-by-step procedure of designing the algorithm first and following up with in-depth analysis and performance improvement to instead applying heuristic-based methods to solve signal-processing problems. In this book the contributing authors demonstrate both general-purpose algorithms and those aimed at solving specialized application problems, with a special emphasis on heuristic iterative optimization methods employing modern evolutionary and swarm...
Numerical study of slip factor model, effect of inlet total pressure and gas composition on the performance curve of centrifugal compressor
, Article ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011 ; Volume 1 , 2011 , Pages 885-895 ; 9780791854877 (ISBN) ; Moshnofi A., M. H ; Karrabi, H ; Soleimani Tehrani, M. R ; ASME ; Sharif University of Technology
2011
Abstract
Development of hardware and CFD codes, especially in turbulence model and optimization of numerical codes has led to increment in usage of CFD which is capable of simulating different experimental situations take place at laboratory. Particularly in issues related to turbo machinery, twodimensional test of blades, three-dimensional investigation of different stages and studying the effect of different parameters are very costly. By means of CFD modeling all these issues are accessible. Actual flow within the compressor is three dimensional and fully turbulent due to geometry complexity, flow velocity and viscosity. For this reason it has become more and more popular to perform 3D numerical...
Parallel Multi-disciplinary Design Optimization of a Guided Flying Vehicle
, M.Sc. Thesis Sharif University of Technology ; Nobahari, Hadi (Supervisor)
Abstract
Multi-disciplinary design optimization (MDO) of a surface to air flying vehicle has been done in this research, on the basis of flight simulation. The MDO problem have five disciplines consists of aerodynamic, propulsion, guidance, control, and fire control. Multiple campaign scenarios are defined. The MDO problem has 31 design variables and two objective functions. The objective functions are flying vehicle weight and miss distance. A new meta-heuristic algorithm has been designed to solve multi-objective optimization problems. The new algorithm has been called Multi-objective Adaptive Real-coded Memetic Algorithm (MARCOMA). The MARCOMA can solve large-scale and multi-objective problems and...
Synthesis and Characterization of PVDF Magnetic Nanocomposite
, M.Sc. Thesis Sharif University of Technology ; Forounchi, Massoud (Supervisor)
Abstract
PVDF (polyvinylidene fluoride) magnetic nanocomposite films were prepared by solution casting using two types of nanomagnetic particles: (i) magnetic nanoparticles synthesized by using an alkaline solution of mixed ferrous/ferric salts along with oleic acid as a coating agent at 70˚C; (ii) Fe3O4 nanoparticles prepared by hydrolysis of aqueous solution of ferrous/ferric salts with potassium hydroxide at room temprature. Scanning electron microscopy (SEM) showed that the PVDF magnetic nanocomposite had a porous structure with Fe3O4 nanoparticles dispersed inside the porous polymer matrix. The presence of crystalline magnetite within the polymer matrix was confirmed by X-Ray diffraction method...
Optimal Design and Real-time Implementation of a Cooperative Guidance Algorithm against a Flying Vehicle
, M.Sc. Thesis Sharif University of Technology ; Nobahari, Hadi (Supervisor)
Abstract
A cooperative aerial system to defense a Ground Station (GS), against an Incoming aerial Targets (IT) is presented. GS is surrounded by given terrains and a group of homogenous Unmanned Aerial Vehicles (UAVs) are employed using a novel online guidance algorithm in a decentralized manner. The proposed algorithm includes loiter, midcourse and terminal phases. During loiter; UAVs follow an optimal circular path. IT is supposed to approach GS along an optimal low altitude trajectory with respect to the terrains. UAVs are informed the initial position and velocity of IT and they are unaware of IT trajectory. Each UAV decides on whether to engage with IT or not, and shares its decision with other...
Development of an Evolutionary Algorithm Based on Surrogate Models to be used in Multi-disciplinary Design Optimization of a Flying Vehicle
, M.Sc. Thesis Sharif University of Technology ; Nobahari, Hadi (Supervisor)
Abstract
In this research, multi-disciplinary design optimization (MDO) of a flying vehicle has been done based on the flight simulation. A meta-heuristic algorithm called Multi-objective Adaptive Real-coded Memetic Algorithm (MARCOMA) has been used for optimization. Since solving a MDO problem is a time consuming process, a RBF neural network has been used in the optimization algorithm as a surrogate model. The new algorithm, called MARCOMA+NN, has been tested with some standard benchmarks. MDO problem has six disciplines consists structure, aerodynamic, propulsion, guidance, control, and fire control. The MDO problem has 31 design variables and two objective functions. The objective functions are...
Cooperative Search and Localization of Aerial Targets, Using a Group of Fixed Wing UAVs
, M.Sc. Thesis Sharif University of Technology ; Nobahari, Hadi (Supervisor)
Abstract
Topic that is investigated in this article include identify and localization a number of aerial target penetrating into a protected by area by a swarm of UAVs is fixed wing. UAVs do not have any prior notice of positioning targets. In addition, it is assumed that lacks any radiation exploitable targets and thus use UAVs for Targets Detection from an active radar system. Obviously this article focus on developing a guidance algorithm UAVs to this particular issue and also as the targets participatory is localization algorithm. In addition, extraction type and performance characteristics radar system required and also performance characteristics of the class of UAVs, which is suitable to...
Cooperative Search and Localization of Mobile RF Ground Targets, Using a Group of UAVs
, M.Sc. Thesis Sharif University of Technology ; Nobahari, Hadi (Supervisor)
Abstract
In this project, a method for cooperative search and localization of RF ground moving targets by a group of UAVs is developed. It should be noted that UAVs are just equipped with GPS and directional sensors. Since there is fuel constraint for UAVs, they take fuel from a tanker whenever they require. Moreover, searching method enables the UAVs to see different parts of the desired area with almost uniform distribution. In addition, the proposed approach enables the UAVs to perform a local search with the aim of finding the targets having lost their signal during localization mode. Finally, based upon a fueling decision function the UAVs take turn, approach to the fuel tanker, and start...
Development of Integrated Model of the Wastewater and Organic Solid Waste Flows to Minimize Environmental Impacts and Maximize Energy Recovery for a Residential Building
, M.Sc. Thesis Sharif University of Technology ; Avami, Akram (Supervisor)
Abstract
Nowdays much of the organic solid waste and wastewater is buried using centralized and traditional methods. This leads to many problems, including groundwater pollution, methane emissions into the atmosphere and rapid transmission of disease. In order to avoid these problems, using a decentralized approach can be a good solution. In this study, recovery of organic waste and wastewater of residential buildings using anaerobic digester as a decentralized way, have been examined. Using experiments, the optimum mass ratio of organic solid waste and wastewater is obtained as 80% and 20% respectively. Biogas production model is developed using mass balance and Balance of electrons in redox...
A New Method for Integrated Controller and Observer Design of a Nonlinear System Using Genetic Programming
, M.Sc. Thesis Sharif University of Technology ; Nobahari, Hadi (Supervisor)
Abstract
The purpose of this paper is to design an integrated controller and observer (ICO) for a nonlinear system using genetic programming. ICO is a function that constructs control command directly from the measured state variables of the system. It means that, this function should imitate the behavior of the observer and controller and control the system with acceptable performance in different initial conditions, at the presence of disturbances and system uncertainties. The complexity of this design method, is not related to the complexity of the plant, in fact, the complexity in plant just effects at run time, but the design procedure does not change. So, if exact model of plant exist, using...
Attitude Control of a 3DOF Quadrotor Stand Using Intelligent Back-stepping Approach
, M.Sc. Thesis Sharif University of Technology ; Nobahari, Hadi (Supervisor)
Abstract
In this research a novel intelligent back-stepping control method is developed. This method is robust to sensor noise and external disturbances. In addition, the controller is robust under model uncertainty. This controller does not need precise knowledge of system parameters. This method is based on three methods of: back-stepping control, least squares estimation and a fuzzy compensator. This controller is used to control quadrotor stand witch is like an inverse pendulum. In quadrotor stand modeling, the inverse pendulum effect is considered too, witch is one of the innovations of the research. By doing various simulations, the validity of controller is tested. Also the performance of the...
Development and Implementation of Multiple Model Filters for Online Identification and Compensation of Atmospheric Disturbances in Automatic Landing of Fixed Wing UAV
, Ph.D. Dissertation Sharif University of Technology ; Nobahari, Hadi (Supervisor)
Abstract
In this study, a multiple model wind estimator is proposed to detect the wind type and to estimate the wind components as well as the states of a fixed-wing UAV without any direct measurement of the air data. Then, the identified wind model and the estimated states are compensated in the heuristic nonlinear model predictive controller during landing phase. For this purpose, a static multiple model approach is taken, comprised of four independent extended Kalman filters, each one is estimating the wind based on one of the four wind models including a constant wind, a “1-cosine” model, a wind shear and a microburst.Moreover, a new heuristic multiple model filter, called Multiple Model Extended...
Dynamic Modelling and Nonlinear Control of a Hybrid Powered Hexarotor for Precise Trajectory Tracking
, M.Sc. Thesis Sharif University of Technology ; Nobahari, Hadi (Supervisor)
Abstract
In this Thesis, an unmanned multicopter with a new structure is modeled and a nonlinear controller is designed for it to track the trajectories precisely. The multicopter in this thesis, has six propellers with a hybrid propulsion system (a combination of fuel and electric propulsion system) that has the ability to carry more payload and maintain more flight duration compared to electric multicopters. In the beginning, the performance characteristics and technical specifications of the hexacopter are presented. For modeling, first the equations of six degrees of freedom movement of the hexacopter are derived by the Newton-Euler method. In the next step, the forces and torques applied to the...
Adaptive Model Predictive Control Applied to Online Automatic Landing of Fixed Wing UAV
, M.Sc. Thesis Sharif University of Technology ; Nobahari, Hadi (Supervisor)
Abstract
The problem that we will solve in this thesis is the automatic landing using model predictive control. Due to the large growth in the use of fixed wing UAVs and the challenges faced by these type of UAVs with respect to other types of UAVs, in this project, the automatic landing of a UAV will be studied in the presence of variable uncertainties with time that will be considered in the modeling. The airplan is assumed to have inertial sensors, gps, speedometer and altimeter. The innovation of the thesis is that until now, Adaptive Model Predictive Control has not been used to control the fixed wing UAV landing. One of the weaknesses in Model Predictive Control is the loss of performance in...