Search for: electric-potential
0.006 seconds
Total 92 records

    A competitive market structure for reactive power procurement

    , Article Iranian Journal of Science and Technology, Transaction B: Engineering ; Volume 30, Issue 2 , 2006 , Pages 259-276 ; 03601307 (ISSN) Mozafari, B ; Ranjbar, A. M ; Amraee, T ; Shirani, A. R ; Sharif University of Technology
    This paper first proposes a competitive market structure for reactive power procurement and then develops a methodology for incorporating voltage stability problems into the model. The owners of electric transactions should participate in this competitive framework and submit their own firmness bids in ($/MW) to the Independent/System/Market Operator (ISOIMO). ISO clears the market for reactive energy regarding the value of each transaction and utilization cost of reactive power on one hand, and the impact of transaction amount on the voltage security of the power system on the other hand. Here, the voltage stability margin is incorporated into the power flow equations so that the security... 

    Axisymmetric thermo-electro-elastic analysis of a piezoelectric half space

    , Article Mathematics and Mechanics of Solids ; Volume 17, Issue 5 , September , 2012 , Pages 500-515 ; 10812865 (ISSN) Kargarnovin, M. H ; Hashemi, R ; Hashemi, M ; Sadeghi, H ; Sharif University of Technology
    In this study, an analytical solution is presented for thermo-electro- elastic analysis of piezoelectric semi-infinite bodies. For this purpose, governing equations are derived for a transversely isotropic piezoelectric material under an axisymmetric thermo-electro-mechanical loading condition. A general closed-form analytical solution is presented for the complementary and particular parts of the components of the displacement vector and also for the electric potential function. Then, boundary conditions are imposed and in that case an explicit solution is obtained for piezoelectric semi-infinite bodies. Results show that when a piezoelectric half space is subjected to constant/ramp surface... 

    A low voltage, high speed, high resolution class AB switched current sample and hold

    , Article ISCAS 2006: 2006 IEEE International Symposium on Circuits and Systems, Kos, 21 May 2006 through 24 May 2006 ; 2006 , Pages 1039-1042 ; 02714310 (ISSN); 0780393902 (ISBN); 9780780393905 (ISBN) Rajaee, O ; Jahanian, A ; Sharif Bakhtiar, M ; Sharif University of Technology
    A high speed, high resolution switched-current sample and hold (SI S/H) based on a new class AB transconductance stage is presented. Simulations performed on the SI S/H in standard 0.18um CMOS technology with 1.5v supply voltage indicate low power dissipation, high sampling speed and high SNR. © 2006 IEEE  

    Investigation of Asphaltene Electro-deposition In Presence of Addetives

    , M.Sc. Thesis Sharif University of Technology Moradpour, Nikoo (Author) ; Ayatollahi, Shahabodin (Supervisor) ; Dehghani, Farzaneh ($item.subfieldsMap.e)
    Given the decreasing trend of light petroleum reserves and the necessity to produce heavy and extra-heavy oil resources, the challenge of dealing with existing asphaltene related problems, which is the heaviest and the most complex component of crude oil, has become increasingly tangible. Asphaltene precipitates and deposits due to pressure, temperature or composition alterations which leads to obstruction of porous media and production facilities. Set the costly methods aside, one of the available approaches to prevent asphaltene precipitation, is to apply an electric field upon the suspected zone, which is cheap and uncomplicated. Besides, utilizing nano-particles while applying electric... 

    Voltammetric behavior and determination of trace amounts of omeprazole using an edge-plane pyrolytic graphite electrode

    , Article Iranian Journal of Pharmaceutical Research ; Volume 14, Issue 2 , Spring , 2015 , Pages 465-471 ; 17350328 (ISSN) Shahrokhian, S ; Ghalkhani, M ; Bayat, M ; Ghorbani Bidkorbeh, F ; Sharif University of Technology
    Iranian Journal of Pharmaceutical Research  2015
    The voltammetric performance of edge-plane pyrolytic graphite (EPG) electrode via adsorptive stripping voltammetry was investigated for study of the electrochemical behavior of omeprazole (OMZ) in aqueous solution. The results revealed that the oxidation of OMZ is an irreversible pH-dependent process that proceeds with the transfer of one electron and one proton in an adsorption-controlled mechanism. The determination conditions, such as the pH values of the supporting electrolyte, accumulation time and scan rate were optimized. Simplicity, high reproducibility and low detection limit (3 nM) of the electrode response as well as wide linear range (0.01 to 4.0 µM) can be stated as significant... 

    Stability analysis and experimental validation of a control strategy for autonomous operation of distributed generation units

    , Article 2010 International Power Electronics Conference - ECCE Asia -, IPEC 2010, 21 June 2010 through 24 June 2010 ; June , 2010 , Pages 464-471 ; 9781424453955 (ISBN) Bahrani, B ; Karimi, H ; Iravani, R ; IEEJ ; Sharif University of Technology
    This paper presents stability analysis of a distributed generation (DG) controller [1], in an islanded mode, based on the Mapping Theorem and the Zero Exclusion Condition, and validates the results based on a laboratory scale experimental setup. The DG unit is interfaced to the host system through a voltage-sourced converter (VSC). The control strategy regulates the load voltage at the desired value in the islanded mode, despite uncertainties in the load parameters. The frequency of the island is controlled in an open loop manner by an internal oscillator. The experimental results show that the controller provides robust voltage control for a wide range of load parameters, and even maintains... 

    Electroosmotic flow and ionic conductance in a pH-regulated rectangular nanochannel

    , Article Physics of Fluids ; Volume 29, Issue 6 , 2017 ; 10706631 (ISSN) Sadeghi, M ; Saidi, M. H ; Sadeghi, A ; Sharif University of Technology
    Infinite series solutions are obtained for electrical potential, electroosmotic velocity, ionic conductance, and surface physicochemical properties of long pH-regulated rectangular nanochannels of low surface potential utilizing the double finite Fourier transform method. Closed form expressions are also obtained for channels of large height to width ratio for which the depthwise variations vanish. Neglecting the Stern layer impact, the effects of EDL (Electric Double Layer) overlap, multiple ionic species, and association/dissociation reactions on the surface are all taken into account. Moreover, finite-element-based numerical simulations are conducted to account for the end effects as well... 

    Precise formulation of electrical capacitance for a cylindrical capacitive sensor

    , Article Journal of Applied Sciences ; Volume 9, Issue 8 , 2009 , Pages 1556-1561 ; 18125654 (ISSN) Azimi, P ; Golnabi, H ; Sharif University of Technology
    In this study a more precise formulation of electrical capacitance for a cylindrical capacitive sensor is reported. By using different theoretical models such as Coulomb law, Gauss law and Laplace equation the electrical capacitance is calculated. Based on the given models the relation between the capacitance and the geometrical parameters (e.g., cylindrical length) is formulated and by using suitable software capacitance variation is computed and compared for different methods. In Coulomb method, the electrical potential is first solved numerically by using Mathematica and then the electrical capacitance is computed. It is found that the active capacitor length is crucial parameter in the... 

    A novel approach for microparticle separation based on dielectrophoresis method

    , Article Biomedical Physics and Engineering Express ; Volume 5, Issue 3 , 2019 ; 20571976 (ISSN) Rafiefard, N ; Sasanpour, P ; Fardindoost, S ; Irajizad, A ; Sharif University of Technology
    Institute of Physics Publishing  2019
    A novel approach for particles size separation based on dielectrophoresis (DEP) method is introduced and analyzed both computationally and experimentally. The proposed technique has been utilized for the separation of polystyrene (PS) particles with 8, 6 and 2 μm diameters passing through microchannels with planar electrodes. The performance of the technique has been computationally analyzed using the finite element method (FEM). Considering the structure of the planar electrodes, we propose an approach based on applying an electric potential between one of the global electrodes, and a needle touched the top of the cell suspension. Results of both simulation and experiment show that by... 

    Effect of rf pumping frequency and RF input power on the flux to voltage transfer function of rf-SQUIDs

    , Article IEEE Transactions on Applied Superconductivity ; Volume 17, Issue 2 , 2007 , Pages 676-679 ; 10518223 (ISSN) Akram, R ; Eker, T ; Bozbey, A ; Fardmanesh, M ; Schubert, J ; Banzet, M ; Sharif University of Technology
    We present the results on the correlation between the flux to voltage transfer function, Vspp, of the rf-SQUID and the rf-bias frequency as well as rf-bias power. Measurements were performed for different SQUID gradiometer samples chosen from the same batch or different batches. In order to have full control on the electronics parameters, an experimental rf-SQUID circuit was designed and implemented with an operation frequency of 600 MHz to 900 MHz. According to our findings, It has been observed that at any particular rf-bias power, Vspp vs. rf-bias frequency shows Sine-like behavior. We observed that the main lobe maxima exist close to the resonance frequency of the LC tank circuit and by... 

    Study of the dependence of the specific output power of a copper chloride laser on the radial temperature profile of a gas plasma

    , Article Quantum Electronics ; Volume 37, Issue 4 , 2007 , Pages 325-330 ; 10637818 (ISSN) Sadighi Bonabi, R ; Soltanmoradi, F ; Mohammadpour, R ; Tavakoli, M ; Zand, M ; Sharif University of Technology
    The design of a copper chloride laser is described, and the laser is optimised by studying the dependence of its output power on the buffer gas type. The voltage and current of the laser discharge at the optimum buffer gas pressure are measured. The influence of the diaphragm diameter on the specific output power is studied after optimisation of switch parameters. When an diaphragm producing the optimal temperature gradient in the laser gas-discharge tube, the record specific output power of 123 W L-1 is obtained without any admixtures. ©2007 Kvantovaya Elektronika and Turpion Ltd  

    Signal enhancement techniques for rf SQUID based magnetic imaging systems

    , Article Superconductor Science and Technology ; Volume 19, Issue 8 , 2006 , Pages 821-824 ; 09532048 (ISSN) Akram, R ; Fardmanesh, M ; Schubert, J ; Zander, W ; Banzet, M ; Lomparski, D ; Schmidt, M ; Krause, H. J ; Sharif University of Technology
    We have investigated the rf SQUID (radio-frequency superconducting quantum interference device) and its coupling to tank circuit configurations to achieve an optimal front-end assembly for sensitive and high spatial resolution magnetic imaging systems. The investigation of the YBCO rf SQUID coupling to the conventional LC tank circuits revealed that coupling from the back of the SQUID substrate enhances the SQUID signal while facilitating the front-end assembly configuration. The optimal thickness of the substrate material between the SQUID and the tank circuit is 0.4 mm for LaAlO3 resulting in an increase of the SQUID flux-voltage transfer function signal, Vspp, of 1.5 times, and 0.5 mm for... 

    Influence of coloring voltage and thickness on electrochromical properties of e-beam eaporated W O3 thin films

    , Article Journal of the Electrochemical Society ; Volume 153, Issue 2 , 2006 , Pages E11-E16 ; 00134651 (ISSN) Azimirad, R ; Akhavan, O ; Moshfegh, A. Z ; Sharif University of Technology
    In this investigation, the effect of coloring voltage and thickness on optical and also electrochromical properties of W O3 thin films has been studied. The W O3 thin films were grown on glass and indium tin oxide coated conducting glass substrates by e-beam evaporation at different thicknesses of 200, 400, and 700 nm. Optical properties of the deposited samples were characterized in the ultraviolet-visible range (300-1100 nm). The optical bandgap energy of the W O3 was obtained in a range of 3.3-3.5 eV showing its increase by decreasing the film thickness. The refractive index of the W O3 films was measured around 2 in the visible range. Surface chemical states of the films were studied by... 

    Direct introduction of semicon layers in XLPE cable model

    , Article 2006 International Conference on Power System Technology, POWERCON2006, Chongqing, 22 October 2006 through 26 October 2006 ; 2006 ; 1424401119 (ISBN); 9781424401116 (ISBN) Hasheminezhad, M ; Vakilian, M ; Blackburn, T. R ; Phung, B. T ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2006
    Detection and location of any partial discharge signal requires an accurate frequency dependent cable model to correctly simulate the P.D. signal attenuation during its propagation in the cable. This model should be capable of simulating the semiconducting layers which have significant effects on P.D. signal attenuation and its propagation velocity. There is a substantial need for improvements in the flexibility of transient cable model through direct introduction of the two semiconducting layers in the cable model. This can be employed, in the next step to develop a 3 phase cable model for ATP. This paper has derived an impedance formula for the semiconducting layers. The propagation... 

    3D numerical analysis of joule heating effect on electroosmotic flow in microchannels

    , Article 4th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM2006, Limerick, 19 June 2006 through 21 June 2006 ; Volume 2006 A , 2006 , Pages 203-208 ; 0791847608 (ISBN); 9780791847602 (ISBN) Monazami, R ; Yazdi, S ; Salehi, M. A ; Sharif University of Technology
    American Society of Mechanical Engineers  2006
    In this paper, a three-dimensional numerical model is developed to analyze the influence of the Joule heating on flow characteristics of an electroosmotic flow through square cross section micro-channels. The governing system of equations consists of three sets of equations: electric potential distribution, flow-field and energy equations. The solution procedure involves three steps. The net charge distribution on the cross section of the micro-channel is computed by solving two-dimensional Poisson-Boltzmann equation using the finite element method. Then, using the computed fluid's charge distribution, the magnitude of the resulting body force due to interaction of an external electric field... 

    A genetic based method for optimal reactive power compensation of transmission network

    , Article Australian Journal of Electrical and Electronics Engineering ; Volume 3, Issue 1 , 2006 , Pages 47-55 ; 1448837X (ISSN) Pirayesh, A ; Vakilian, M ; Sharif University of Technology
    Institution of Engineers (Australia)  2006
    Reactive power compensation is known as an effective tool to overcome the violations of voltage limits in electric power systems. It is also deployed to be an efficient method to minimise transmission losses. In order to maximize the effectiveness of reactive power compensation, VAr sources of proper sizes should be placed at some network buses. In this paper, a new VAr expansion tool has been developed to improve the voltage profile and reduce MW losses in a bulk power network. Keeping the minimum expansion cost and minimum switching of capacitor banks during change of load level of the system are emphasized in the proposed method. This method is based on application of genetic algorithm in... 

    GA-based optimization of total harmonic current distortion and suppression of chosen harmonics in induction motors

    , Article International Symposium on Power Electronics, Electrical Drives, Automation and Motion, 2006. SPEEDAM 2006, Taormina, 23 May 2006 through 26 May 2006 ; Volume 2006 , 2006 , Pages 1361-1366 ; 1424401941 (ISBN); 9781424401949 (ISBN) Sayyah, A ; Aflaki, M ; Rezazade, A. R ; Sharif University of Technology
    In this study, a genetic algorithm optimization technique is applied, to minimize the total harmonic current distortion (THCD) in induction motors fed by high power inverters, based on an approximate model. That is, having defined a desired fundamental output voltage, optimal pulse patterns (switching angles) are determined to produce the fundamental output voltage while minimizing the THCD. The complete results for two cases of 3 and 5 switching instants in the first quarter period of PWM waveform are presented. In the sequel, considering that the torque pulsation is mainly affected by the presence of low-order harmonics, the fifth, seventh, 11th, and 13th order harmonics (in the case of 5... 

    Optimization of THD and suppressing certain order harmonics in PWM inverters using genetic algorithms

    , Article Joint 2006 IEEE Conference on Control Applications (CCA), Computer-Aided Control Systems Design Symposium (CACSD) and International Symposium on Intelligent Control (ISIC), Munich, 4 October 2006 through 6 October 2006 ; 2006 , Pages 874-879 ; 0780397983 (ISBN); 9780780397989 (ISBN) Sayyah, A ; Aflaki, M ; Rezazade, A. R ; Sharif University of Technology
    In this paper the aim is to minimize the total harmonic distortion (THD) in PWM inverters while suppressing chosen harmonics concurrently and maintaining the fundamental component of the output voltage at a required level. This is reformed as an optimization task and the optimal pulse patterns are accomplished using genetic algorithm (GA) optimization technique to minimize a predefined fitness function. The complete solutions that suppress the 5 th and 7 th harmonics and optimize the THD are given. A practical limitation on the determination of sequential switching angles has been considered as a set of constraints in derivation of the results. © 2006 IEEE  

    A numerical procedure for obtaining the static and pull-in deflection and voltage of capacitive microcantilever beams

    , Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) Ghaemi Oskouei, B ; Alasty, A ; Sharif University of Technology
    A numerical procedure is proposed for obtaining the static deflection, pull-in (PI) deflection and PI voltage of electrostatically excited capacitive microcantilever beams. The method is not time and memory consuming as Finite Element Analysis (FEA). Nonlinear ordinary differential equation of the static deflection of the beam is derived, w/wo considering the fringing field effects. The nondimensional parameters upon which PI voltage is dependent are then found. Thereafter, using the parameters and the numerical method, three closed form equations for pull-in voltage are developed. The results are in good agreement with others in literature. Copyright © 2006 by ASME  

    Biodegradation of heavy fuel oil by newly isolated strain enterobacter cloacae BBRC10061: Study of unstructured kinetic models and innovative equation

    , Article Scientia Iranica ; Volume 20, Issue 6 , 2013 , Pages 1929-1938 ; 10263098 (ISSN) Chackoshian Khorasani, A ; Mashreghi, M ; Yaghmaei, S ; Sharif University of Technology
    Sharif University of Technology  2013
    Modeling process is very important and valuable to predict process outcome, especially bioprocesses which are intricate. Because of complex hydrocarbon compounds and oscillations happened in the medium of process, biodegradation of mazut has not already been investigated by mathematical models. In this study, an indigenous bacterium was isolated from oil contaminated soil to investigate biodegradation of mazut at different experimental conditions. Data resulted from mazut degradation, pH, and electrical potential in the medium were recorded. Some reported kinetic models and combinations were investigated to practically model the process. In addition, a new equation that can predict various...