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Multiobjective optimization scheme for industrial synthesis gas sweetening plant in GTL process

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Journal of Natural Gas Chemistry 2011年第1期20卷 99-109页

作者： alireza Behroozsarand Akbar Zamaniyan Department of Chemical Engineering Islamic Azad University Department of Natural Gas Conversion Gas Research Division Research Institute of Petroleum Industry (RIPI)

In industrial amine plants the optimized operating conditions are obtained from the conclusion of occurred events and challenges that are normal in the working units. For the sake of reducing the costs, time consuming, and preventing unsuitable accidents, the optimization could be performed by a computer program. In this paper, simulation and parameter analysis of amine plant is performed at first. The optimization of this unit is studied using Non-Dominated Sorting Genetic Algorithm-II in order to produce sweet gas with CO 2 mole percentage less than 2.0% and H 2 S concentration less than 10 ppm for application in Fischer-Tropsch synthesis. The simulation of the plant in HYSYS v.3.1 software has been linked with MATLAB code for real-parameter NSGA-II to simulate and optimize the amine process. Three scenarios are selected to cover the effect of （DEA/MDEA） mass composition percent ratio at amine solution on objective functions. Results show that sour gas temperature and pressure of 33.98 ？ C and 14.96 bar, DEA/CO 2 molar flow ratio of 12.58, regeneration gas temperature and pressure of 94.92 ？ C and 3.0 bar, regenerator pressure of 1.53 bar, and ratio of DEA/MDEA = 20%/10% are the best values for minimizing plant energy consumption, amine circulation rate, and carbon dioxide recovery.

关键词： amine plant multiobjective optimization Non-Dominated Sorting Genetic Algorithm amine circulation rate

Robust pre-specified time synchronization of chaotic systems by employing time-varying switching surfaces in the sliding mode control scheme

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Chinese Physics B 2016年第8期25卷 86-93页

作者： alireza Khanzadeh Mahdi Pourgholi Faculty of Electrical Engineering Shahid Beheshti University

In the conventional chaos synchronization methods, the time at which two chaotic systems are synchronized, is usually unknown and depends on initial conditions. In this work based on Lyapunov stability theory a sliding mode controller with time-varying switching surfaces is proposed to achieve chaos synchronization at a pre-specified time for the first time. The proposed controller is able to synchronize chaotic systems precisely at any time when we want. Moreover, by choosing the time-varying switching surfaces in a way that the reaching phase is eliminated, the synchronization becomes robust to uncertainties and exogenous disturbances. Simulation results are presented to show the effectiveness of the proposed method of stabilizing and synchronizing chaotic systems with complete robustness to uncertainty and disturbances exactly at a pre-specified time.

关键词： chaos synchronization finite time synchronization sliding mode controller time varying switching surfaces

Investigation of the stress rupture behavior of GTD-111 superalloy melted by VIM/VAR

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International Journal of Minerals,Metallurgy and Materials 2018年第9期25卷 1035-1041页

作者： Ainaz Agh alireza Amini Department of Materials Engineering Islamic Azad University Karaj Branch

The effects of vacuum induction melting(VIM) and vacuum arc remelting(VAR) processes on the microstructure and stress rupture properties of Ni-based GTD-111 superalloy were investigated. Samples of GTD-111 master alloy were melted in VIM and VAR furnaces and then poured into a preheated ceramic mold for VIM melt or into a water-cooled copper mold for VAR melt. The as-cast samples were examined radiographically to ensure that no casting defects were present in the final castings; the samples were then heat-treated using a standard heat-treatment cycle. The microstructure of the samples was investigated using optical microscopy and scanning electron microscopy in conjunction with energy-dispersive X-ray spectroscopy for microanalysis. On the basis of standard ASTM-E139, stress rupture tests were carried out at 1000°C under a stress of 300 MPa. The results showed that a γ matrix, fine γ′ precipitates, a γ–γ′ eutectic structure, carbide particles, and some harmful phases such as σ and η phases were present in the as-cast samples. The γ′ precipitates with cubic morphology appeared in the matrix after the standard heat-treatment process. The extent of segregation and the amount of γ–γ′ eutectic structure formed in the VAR-prepared sample were less than in the VIM-prepared sample. The results of stress rupture tests showed that the rupture time for the VAR sample was 43% longer than that for the VIM sample.

关键词： GTD-111 vacuum induction melting(VIM) vacuum arc remelting(VAR) stress rupture

Effects of Magnetic Particles Entrance Arrangements on Mixing Efficiency of a Magnetic Bead Micromixer

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Nano-Micro Letters 2014年第1期6卷 30-37页

作者： Reza Kamali Seyed alireza Shekoohi alireza Binesh School of Mechanical Engineering Shiraz University

In this study, a computer code is developed to numerically investigate a magnetic bead micromixer under different conditions. The micromixer consists of a microchannel and numerous micro magnetic particles which enter the micromixer by fluid flows and are actuated by an alternating magnetic field normal to the main flow. An important feature of micromixer which is not considered before by researchers is the particle entrance arrangement into the micromixer. This parameter could effectively affect the micromixer efficiency. There are two general micro magnetic particle entrance arrangements in magnetic bead micromixers: determined position entrance and random position entrance. In the case of determined position entrances, micro magnetic particles enter the micromixer at specific positions of entrance cross section. However, in a random position entrance,particles enter the microchannel with no order. In this study mixing efficiencies of identical magnetic bead micromixers which only differ in particle entrance arrangement are numerically investigated and *** results reported in this paper illustrate that the prepared computer code can be one of the most powerful and beneficial tools for the magnetic bead micromixer performance analysis. In addition, the results show that some features of the magnetic bead micromixer are strongly affected by the entrance arrangement of the particles.

关键词： Magnetic bead micromixer Mixing efficiency Particle entrance arrangement

ASSESSMENT OF BED-LOAD PREDICTORS BASED ON SAMPLING IN A GRAVEL BED RIVER

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Journal of Hydrodynamics 2012年第1期24卷 145-151页

作者： HADDADCHI arman.OMID Mohammad H. DEHGHANI Amir A. School of Environment Griffith UniversityNathanQld 4111Australia Department of Irrigation and Reclamation Engineering University of TehranTehranIran Department of Irrigation Engineering Golestan Agriculture and Natural Resources UniversityGorganIran

Bedload transport in alluvial channels has been extensively studied and different equations based on field and/or experimental data have been *** of bed-load transport rate using different equations results in wide ranges which are not always *** this study,some of the universal bedload predictors were evaluated with measured load by a Helley-Smith sampler in the Node River,a gravel bed river in the northeast part of *** 19 sets of data,14 series of data were used to evaluate the bed-load transport *** results show that the equations presented by Van Rijn,Meyer-Peter and Mueller,and Ackers and White may adequately predict bedload transport in the range of field data.

关键词： bedload transport gravel bed river bed-load sampling Gorgan-Iran

Intelligent modeling and identification of aircraft nonlinear flight

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Chinese Journal of Aeronautics 2014年第4期27卷 759-771页

作者： alireza Roudbari Fariborz Saghafi Department of Aerospace Engineering Sharif University of Technology

In this paper, a new approach has been proposed to identify and model the dynamics of a highly maneuverable fighter aircraft through artificial neural networks（ANNs）. In general, aircraft flight dynamics is considered as a nonlinear and coupled system whose modeling through ANNs, unlike classical approaches, does not require any aerodynamic or propulsion information and a few flight test data seem sufficient. In this study, for identification and modeling of the aircraft dynamics, two known structures of internal and external recurrent neural networks（RNNs） and a proposed structure called hybrid combined recurrent neural network have been used and *** order to improve the training process, an appropriate evolutionary method has been applied to simultaneously train and optimize the parameters of ANNs. In this research, it has been shown that six ANNs each with three inputs and one output, trained by flight test data, can model the dynamic behavior of the highly maneuverable aircraft with acceptable accuracy and without any priori knowledge about the system.

关键词： Flight test Genetic algorithms Nonlinear flight dynamicsNonlinear systemidentification Recurrent neural network

Implementation of electrolyte CPA EoS to model solubility of CO2 and CO2+ H2S mixtures in aqueous MDEA solutions

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Chinese Journal of Chemical Engineering 2019年第8期27卷 1912-1920页

作者： alireza Afsharpour Ali Haghtalab Department of Chemical Engineering Tarbiat Modares UniversityP.O.Box 14115-114TehranIran Faculty of Chemical and Materials Engineering Shahrood University of TechnologyShahroodIran

The electrolyte version of SRK plus association equation of state(e SRK-CPA Eo S) was employed to correlate CO2 solubility in MDEA aqueous solutions. The applied model comprises the classic form of CPA Eo S including SRK Eo S plus Wertheim association term in addition to MSA theory and Born terms so that the two last terms are responsible for the long-range interactions. A reaction-containing bubble pressure computation technique comprising two nested loops was utilized to model the systems. The internal loop, calculates the liquid phase concentrations via reaction, mass and charge balance equation solving, whereas, the vapor phase concentrations will be obtained in the external one. 470 experimental data were used to correlate binary subsystems and the H2O + MDEA + CO2 ternary system. Since, there not exist any binary VLE data for MDEA + CO2 subsystem, two fitting scenarios were applied. At the first scenario, the binary interaction parameter was assumed equal to zero, while, in second approach the parameter was obtained through ternary system correlation. Both scenarios show very good accuracy in that the Absolute Average Deviation percentages(AAD) obtained were 19.12% and 18.85%, respectively. Also, to show the efficiency of the used model, a comparison between our results and those of the best-known models was ***, having model parameters for H2S solubility from our previous work [A. Afsharpour, Petroleum Science and Technology 35(3)(2017) 292-298], simultaneous solubility of CO2+ H2S mixtures in MDEA solutions was predicted using the e SRK-CPA Eo S with no new optimizable parameters. As the results show,the applied model has a good performance for correlation and prediction of acid gas solubility in a wide range of pressures, temperatures, acid gas loadings, and MDEA concentrations.

关键词： Acid gas solubility MDEA Thermodynamic modeling Phase equilibria CPA EoS Prediction

Reliability Assessment of Integrated Electricity and Natural Gas Transmission Systems in Presence of Power-to-gas and Combined Heat and Power Technologies

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CSEE Journal of Power and Energy Systems 2023年第3期9卷 1193-1202页

作者： alireza Tabebordbar Mohammad Rastegar School of Electrical and Computer Engineering Shiraz UniversityShiraz 71946-84636Iran(the Islamic Republic of)

Assessing the reliability of integrated electricity and gas systems has become an important issue due to the strong dependence of these energy networks through the power-to-gas(P2G)and combined heat and power(CHP)*** current work,initially,presents a detailed energy flow model for the integrated power and natural gas system in light of the P2G and CHP *** the simultaneous load flow of networks,a contingency analysis procedure is proposed,and reliability is assessed through sequential Monte Carlo *** current study examines the effect of independent and dependent operation of energy networks on the reliability of the *** particular,the effect of employing both P2G and CHP technologies on reliability criteria is *** addition,a series of sensitivity analysis are performed on the size and site of these technologies to investigate their effects on system *** proposed method is implemented on an integrated IEEE 24-bus electrical power system and 20-node Belgian natural gas *** simulation procedure certifies the proposed method for reliability assessment is practical and *** addition,the results prove connection between energy networks through P2G and CHP technologies can improve reliability of networks if the site and size of technologies are properly determined.

关键词： CHP technology P2G technology integrated electrical power and natural gas network reliability assessment sequential Monte Carlo simulation method

Nonlinear vibration analysis of a circular micro-plate in two-sided NEMS/MEMS capacitive system by using harmonic balance method

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Acta Mechanica Sinica 2019年第1期35卷 129-143,I0004页

作者： Milad Saadatmand alireza Shooshtari Department of Electrical Engineering Technical University of DenmarkKgs.LyngbyDenmark Department of Mechanical Engineering Bu-Ali Sina UniversityHamedanIran

In this study, forced nonlinear vibration of a circular micro-plate under two-sided electrostatic, two-sided Casimir and external harmonic forces is investigated analytically. For this purpose, at first, von Karman.plate theory including geometrical nonlinearity is used to obtain the deflection of the micro-plate. Galerkin decomposition method is then employed, and nonlinear ordinary differential equations (ODEs) of motion are determined. A harmonic balance method (HBM) is applied to equations and analytical relation for nonlineaT frequency response (F-R) curves are derived for two categories (including and neglecting Casimir force) separately. The analytical results for three cases:(1) semi-linear vibration;(2) weakly nonlinear vibration;(3) highly non linear vibration, are validated by comparing with the numerical solutio ns. After validation, the effects of the voltage and Casimir force on the natural frequency of two-sided capacitor system are investigated. It is shown that by assuming Casimir force in small gap distances, reduction of the natural frequency is considerable. The influences of the applied voltage, damping, micro-plate thickness and Casimir force on the frequency response curves have been presented too. The results of this study can be useful for modeling circular parallel-plates in nano /microelectromechanical transducers such as microphones and pressure sensors.

关键词： Nonlinear vibration Two-sided MEMS capacitor Circular plate Harmonic balance method