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Coordinated Voltage Control of Power Systems in Normal and Emergency Operation States
, Ph.D. Dissertation Sharif University of Technology ; Parniani, Mostafa (Supervisor)
Abstract
One of the main objectives in operating a power system is to maintain the system voltage properly to avoid equipment damage and transfer power efficiently. Automatic control of transmission network voltage provides significant improvements in security, quality and efficiency of power system operation. This thesis investigates coordinated voltage control of power systems in normal, alert and emergency states. The aim is to propose a comprehensive framework for real-time operation of practical power systems, ensuring secure operation of the system in the normal state and after occurrence of sever contingencies.
At the first, a new coordinated voltage control scheme is proposed to ensure...
At the first, a new coordinated voltage control scheme is proposed to ensure...
Application of Ultrasonic Technique to Improve Food Processing and Yield Enhancement in Food Industry
, M.Sc. Thesis Sharif University of Technology ; Roosta Azad, Reza (Supervisor) ; Aalemzadeh, Iran (Supervisor) ; Ghotbi, Siroos (Supervisor)
Abstract
In this project we focused on Ultrasonic waves as novel, effective and well-controllable means for cell wall disruption and disintegration to provide faster and more complete penetration of solvent into cellular materials and improve sugar mass transfer and extraction from sugarcane and sugar beet. Impact of frequency, temperature, power density and reactor shape on Ultrasonic wave efficiency in extraction process has been investigated and the result was utilized to design a semi-pilot reactor. In the optimum situation, sucrose extraction from sugarcane improved to 4.51 gr/100 ml H2O that had a significant increasing from 2.1 gr/100 ml H2O extraction in thermal only process at 70 °C. Optimum...
Newton's Method for Vector Optimization
, M.Sc. Thesis Sharif University of Technology ; Razvan, Mohammad Reza (Supervisor) ; Khorram, Esmaeil (Supervisor)Developing a Planning Model for a Multi-hub Energy System in the Oligopoly Market
, Ph.D. Dissertation Sharif University of Technology ; Rajabi Ghahnuyeh, Abbas (Supervisor)
Abstract
Restructuring energy systems for increasing the competence and improving the efficiency has been regarded by energy policy makers. Also, the emerging of new technologies and also the district generation has increased the competence in energy industry. Planning and exploiting the energy system in a restructured environment, has basic differences with integrated systems. Models that can assess the behavior of independent players are needed to assess energy systems in a restructured space.The goal of the present study is to present a model to optimally develop the energy system in a restructured environment. The concept of energy hub was applied to model multicarrier systems. Three steps were...
, M.Sc. Thesis Sharif University of Technology ; Farhadi, Fathollah (Supervisor)
Abstract
The aim of this project is Industrial Solvents (White Spirit) producing in Tehran Refinery. For this manner “Wild Naphtha” from Gasoil Hydrotreater and Kerosene Hydrotreater Units was chosen as feed stock for solvents preparation. In addition, Pentane Recovery Column is selected for Simulation and Optimization based on Wild Naphtha. As a Result, Abadan White Spirit 402 and 410 has been produced and a side stream which is full of Aromatic is obtained. Simultaneously, Tray Hydraulics and Solvents production in different cases (Various Pressure and different Split Ratio of Feed Stock) are evaluated, so optimum Tower process conditions such as pressure, Temperature and Split Ratio of Feed Stock...
Optimization of Encapsulation of Probiotic Living Cells
, M.Sc. Thesis Sharif University of Technology ; Alemzadeh, Iran (Supervisor)
Abstract
In the recent year, there has been a rising interest in producing functional foods containing encapsulated probiotic bacteria according to their perceived health benefits. Probiotics are feed and food supplements that beneficially affect the host’s health. The term “probiotic” includes a large range of microorganisms, mainly lactic acid bacteria. Because they can stay alive until the intestine and provide health beneficial effects like lowering cholesterol, improving lactose tolerance and preventing some cancers like colon cancer on the host health. It has been recommended that the viability of probiotics should be at least 107 CFU/ml of product at time of consumptions to provide selective...
Co-planning of Transmission System and Merchant Energy Storage
, M.Sc. Thesis Sharif University of Technology ; Hosseini, Hamid (Supervisor)
Abstract
Dependency of human life to supplying of electricity energy, leads to different challenges for power system operators and planners. Demand growth and development of renewable energy sources have caused heavy investment costs to the transmission system. High price of construction of new transmission lines make planners to investigate effective factors on transmission expansion planning in order to make better decisions. On the other hand, the different amount of energy consumption during a day and the uncertainty of renewable energy result in transmission line congestion which cause electricity price gap between peak hours and off-peak hours. This price gap, also, necessitate the development...
Investigation and Optimization of Structural Parameters of an Elastic Flapping Wing
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firouzabadi, Roohollah (Supervisor)
Abstract
In this thesis, effects of bending and torsional elasticity of a flapping wing on its average lift and input power are studied, using a semi-analytic method. Bending stiffness and torsional rigidity of wing spar, wing mass ratio and chordwise and spanwise center of gravity, also spar location are considered as variables for controlling elastic behavior of the wing.Governing integral equation is derived using Hamilton principle via modified quasi aerodynamic and linear Green-Lagrange strain tensor. Also an idealized flapping pattern is used to maximize average acceleration during each cycle. Next, integral equation is converted to a set of ordinary differential equations by means of Galerkin...
Optimal Control Problem for an Ecosystem With Two Competing Preys and One Predator
, M.Sc. Thesis Sharif University of Technology ; Hesaraki, Mahmoud (Supervisor)
Abstract
this work devoted to the optimal control problem for an ecosystem composed of one predator and two competing preys, and our goal is to maximize the total density of the three populations. we first investigate the existence and uniqueness of the positive strong solution for the controlled system, and find an optimal solution under given initial conditions. then we establish the first order necessary optimality condition, and point out that the optimal control has a bang-bang form. moreover, the second order necessary and sufficient optimality conditions are established
Note on Local Quadratic Growth Estimates in Bang-Bang Optimal Control Problems
, M.Sc. Thesis Sharif University of Technology ; Hesaaraki, Mahmoud (Supervisor)
Abstract
In optimal control,local quadratic growth estimation in case of continuous control functions, and for bang–bang optimal controls when the state system is linear, has been obtained. The paper provides a generalization of the latter result to bang–bang optimal control problems for systems which are affine-linear w.r.t. the control but depend nonlinearly on the state.Local quadratic growth in terms of L1 norms of the control variation are obtained under appropriate structural and second-order sufficient optimality conditions
Voltage security constrained multi-period optimal reactive power flow using benders and optimality condition decompositions
, Article IEEE Transactions on Power Systems ; Volume 28, Issue 2 , 2013 , Pages 696-708 ; 08858950 (ISSN) ; Parniani, M ; Sharif University of Technology
2013
Abstract
This paper proposes a new coordinated voltage control scheme to ensure voltage security of power systems. The scheme schedules reactive power injection from VAR sources, including synchronous generators and condensers, capacitor banks, switchable reactors and FACTS devices, to ensure desired loading margin of power systems for a given horizon of time. The problem is treated as voltage security constrained multi-period optimal reactive power flow (VSC-MPORPF). To incorporate scheduling of both continuous and discrete VAR sources, the VSC-MPORPF is formulated as a mixed-integer nonlinear programming problem, and is solved using generalized Benders decomposition (GBD). Multi-period formulation...
Vancomycin removal using TiO2–clinoptilolite/UV in aqueous media and optimisation using response surface methodology
, Article International Journal of Environmental Analytical Chemistry ; 2022 ; 03067319 (ISSN) ; Yousefinejad, S ; Dehghani, M ; Borghei, S. M ; Javid, A. H ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
Investigations have shown the traces of antibiotics in surface water, groundwater, wastewater treatment plants, and drinking water. However, conventional wastewater treatment is not entirely effective for vancomycin degradation. Advanced oxidation is one of the most widespread methods of antibiotic degradation in aqueous media. Vancomycin was quantified by high-performance liquid chromatography. The Response Surface Methodology (RSM) based on Central Composite Design (CCD) was used to explore and optimise the effect of the independent variables on vancomycin degradation. Independent variables were as follows: pH (3–11), vancomycin concentration (15–75 mg/L), TiO2–clinoptilolite (25–125 mg in...
Using genetic algorithm and artificial neural network analyses to design an Al-Si casting alloy of minimum porosity
, Article Materials and Design ; Volume 27, Issue 7 , 2006 , Pages 605-609 ; 02641275 (ISSN) ; Bahrami, A ; Madaah Hosseini, H. R ; Shafyei, A ; Sharif University of Technology
2006
Abstract
In this investigation a theoretical model based on artificial neural network (ANN) and genetic algorithm (GA) has been developed to optimize effective parameters on porosity formation in Al-Si casting alloys. The ANN theory was used to correlate the chemical composition and cooling rate to the amount of porosity. The GA and ANN were incorporated to find the optimal conditions for achieving the minimum porosity percent. By comparing the predicted values with the experimental data - earlier deduced by Dash et al. - it is demonstrated that the combined GA-ANN model is a useful and efficient method to find the optimal conditions for casting of Al-Si alloys associated with the minimum porosity...
Ultrasonic assisted deep drilling of Inconel 738LC superalloy
, Article Procedia CIRP, Leuven ; Volume 6 , April , 2013 , Pages 571-576 ; 22128271 (ISSN) ; Mehbudi, P ; Akbari, J ; Sohrabi, M ; Sharif University of Technology
2013
Abstract
Superalloys have a poor machinability and are often drilled using Electro Discharge Machining (EDM) methods. However EDM is a time-consuming process and has low surface integrity. Ultrasonic Assisted Drilling (UAD) technology is a modern method of drilling such materials. Although this method has very high capabilities, it has not been introduced widely to industry. In this study a special horn is designed and used to apply both rotation and vibration to drill bits. It can transfer power with high efficiency and has the capability to change tools easily. The setup is used to conduct deep drilling tests on Inconel 738LC with depth-to-diameter ratio of 10. The effect of ultrasonic vibration...
Tunable photon statistics in a non-Hermitian system
, Article Journal of the Optical Society of America B: Optical Physics ; Volume 34, Issue 3 , 2017 , Pages 566-573 ; 07403224 (ISSN) ; Zandi, M. H ; Bahrampour, A ; Sharif University of Technology
OSA - The Optical Society
2017
Abstract
In the present study, the antibunching effect is considered in a parity time (PT)-symmetric system, using the recently proposed non-Hermitian model for resonant cavities. The model consists of a cavity coupled to an optomechanical system by a chiral mirror, with both cavities being driven coherently. The nonreciprocal coupling strength between the two cavities leads to the generation of the non-Hermitian but PT-symmetric model. The optimal conditions of strong antibunching are calculated in this system, and then the antibunching effect is considered using the two-photon correlation function and the Wigner function. The results showed that this model presented the best control over the strong...
Thermal optimization of the continuous casting process using distributed parameter identification approach—controlling the curvature of solid-liquid interface
, Article International Journal of Advanced Manufacturing Technology ; Volume 94, Issue 1-4 , 2018 , Pages 1101-1118 ; 02683768 (ISSN) ; Sharif University of Technology
Springer London
2018
Abstract
Thermal optimization of the vertical continuous casting process is considered in the present study. The goal is to find the optimal distribution of the temperature and interfacial heat transfer coefficients corresponding to the primary and secondary cooling systems, in addition to the pulling speed, such that the solidification along the main axis of strand approaches to the unidirectional solidification mode. Unlike many thermal optimization of phase change problems in which the desirable (target) temperature, temperature gradient, or interface position are assumed to be a priori known, a desirable shape feature of the freezing interface (not its explicit position) is assumed to be known in...
Thermal characteristics of closed loop pulsating heat pipe with nanofluids
, Article Journal of Enhanced Heat Transfer ; Volume 18, Issue 3 , 2011 , Pages 221-237 ; 10655131 (ISSN) ; Arabnejad, S ; Shafii, M. B ; Saboohi, Y ; Sharif University of Technology
2011
Abstract
In this paper, the effect of different parameters on the thermal operation of a Closed Loop Pulsating Heat Pipe (CLPHP) has been investigated. These parameters include the working fluid, the inclination angle, the filling ratio, and the input heat flux. The effect of nanoparticle mass concentrations has been analyzed as well. It was observed that the CLPHP can decrease thermal resistance up to 11.5 times compared to the same empty copper tube with thermal resistance of 9.4 K/W. Optimum thermal operation for a system with the water-silver nanofluid was achieved at conditions of the 50% filling ratio with thermal resistance of 0.9 K/W, and for the water-titanium oxide system, the optimal...
Tailoring of morphology and crystal structure of CdSe nanostructures by controlling the ratio of triethylenetetraamine and water in their mixed solution
, Article Applied Physics A: Materials Science and Processing ; Volume 107, Issue 2 , May , 2012 , Pages 497-502 ; 09478396 (ISSN) ; Zarghami, V ; Fray, D. J ; Sharif University of Technology
2012
Abstract
The morphological manipulation, structural characterization, and optical properties of different CdSe nanocrystals were reported. Several different CdSe nanostructures, including nanowires, tetrapod crystals, and nanoparticles were grown by varying the volume ratio of triethylenetetraamine (TETA) and water (WA) in their mixed solution. By manipulating the growth driving force (i.e., the degree of supersaturation) and kinetics of the process (i.e., growth rate), the morphology and crystal structure of CdSe nanocrystals can be tailored. Growth driving force changed their morphology from nanowires to tetrapod structures and from the latter structure to nanoparticles. Moreover, kinetics of the...
Synthesis of nanostructured and nanoporous TiO2-AgO mixed oxide derived from a particulate sol-gel route: Physical and sensing characteristics
, Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 42, Issue 8 , August , 2011 , Pages 2481-2492 ; 10735623 (ISSN) ; Fray, D. J ; Sharif University of Technology
2011
Abstract
Nanocrystalline TiO2-AgO thin films and powders were prepared by an aqueous particulate sol-gel route at the low temperature of 573 K (300 °C). Titanium tetraisopropoxide and silver nitrate were used as precursors, hydroxypropyl cellulose was used as a polymeric fugitive agent in order to increase the specific surface area. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) revealed that the phase composition of the mixed oxide depends upon the annealing temperature, being a mixture of TiO2 and AgO in the range 573 K to 773 K (300 °C to 500 °C) and a mixture of TiO2, AgO, Ag2O at 973 K (700 °C). Furthermore, one of the smallest crystallite sizes was obtained for TiO...
Synthesis and electrochemical properties of LiNi0.8Co 0.2O2 nanopowders for lithium ion battery applications
, Article Journal of Power Sources ; Volume 196, Issue 1 , 2011 , Pages 337-342 ; 03787753 (ISSN) ; Asgari, S ; Sharif University of Technology
Abstract
Nitrates of lithium, cobalt and nickel are utilized to synthesize LiNi 0.8Co0.2O2 cathode material through sol-gel technique. Various synthesis parameters such as calcination time and temperature as well as chelating agent are studied to determine the optimized condition for material processing. Using TG/DTA techniques, the optimized calcination temperatures are selected. Different characterization techniques such as ICP, XRD and TEM are employed to characterize the chemical composition, crystal structure, size and morphology of the powders. Micron and nano-sized powders are produced using citric/oxalic and TEA as chelating agent, respectively. Selected powders are used as cathode material...