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Dynamic Positioning System Design for A Marine Vessel with Unknown Dynamics Subject to External Disturbances Including Wave Effect

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China Ocean Engineering 2020年第5期34卷 651-663页

作者： alireza HOSSEINNAJAD Mehdi LOUEIPOUR Department of Mechanical Engineering Isfahan University of TechnologyIsfahanIran Research Institute for Subsea Science and Technology Isfahan University of TechnologyIsfahanIran

In this paper, a new control system is proposed for dynamic positioning(DP) of marine vessels with unknown dynamics and subject to external disturbances. The control system is composed of a substructure for wave filtering and state estimation together with a nonlinear PD-type controller. For wave filtering and state estimation, a cascade combination of a modified notch filter and an estimation stage is considered. In estimation stage, a modified extended-state observer(ESO) is proposed to estimate vessel velocities and unknown dynamics. The main advantage of the proposed method is its robustness to model uncertainties and external disturbances and it does not require prior knowledge of vessel model parameters. Besides, the stability of the cascade structure is analyzed and input to state stability(ISS) is guaranteed. Later on, a nonlinear PD-type controller with feedforward of filtered estimated dynamics is utilized. Detailed stability analyses are presented for the closed-loop DP control system and global uniform ultimate boundedness is proved using large scale systems method. Simulations are conducted to evaluate the performance of the proposed method for wave filtering and state estimation and comparisons are made with two conventional methods in terms of estimation accuracy and the presence of uncertainties. Besides, comparisons are made in closed-loop control system to demonstrate the performance of the proposed method compared with conventional methods. The proposed control system results in better performance in the presence of uncertainties,external disturbance and even in transients when the vessel is subjected to sudden changes in environmental disturbances.

关键词： dynamic positioning environmental disturbances marine vessel state estimation unknown dynamics wave filtering

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Optimal State Estimation and Fault Diagnosis for a Class of Nonlinear Systems

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IEEE/CAA Journal of Automatica Sinica 2020年第2期7卷 517-526页

作者： Hamed Kazemi alireza Yazdizadeh Department of Electrical Engineering Shahid Beheshti UniversityTehran ***Iran

This study proposes a scheme for state estimation and,consequently,fault diagnosis in nonlinear ***,an optimal nonlinear observer is designed for nonlinear systems subject to an actuator or plant *** utilizing Lyapunov's direct method,the observer is proved to be optimal with respect to a performance function,including the magnitude of the observer gain and the convergence *** observer gain is obtained by using approximation of Hamilton-Jacobi-Bellman(HJB)*** approximation is determined via an online trained neural network(NN).Next a class of affine nonlinear systems is considered which is subject to unknown disturbances in addition to fault *** this case,for each fault the original system is transformed to a new form in which the proposed optimal observer can be applied for state estimation and fault detection and isolation(FDI).Simulation results of a singlelink flexible joint robot(SLFJR)electric drive system show the effectiveness of the proposed methodology.

关键词： Differential geometry fault detection and isolation(FDI) fault diagnosis neural network(NN) nonlinear observer and filter design optimal state estimation

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Influence of surface cracking,anchor head profile,and anchor head size on cast-in headed anchors in geopolymer concrete

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Frontiers of Structural and Civil Engineering 2023年第8期17卷 1163-1187页

作者： Trijon KARMOKAR alireza MOYHEDDIN School of Engineering Edith Cowan UniversityPerth 6027Australia

In this study,the concrete cone capacity,concrete cone angle,and load–displacement response of cast-in headed anchors in geopolymer concrete are explored using numerical *** concrete damaged plasticity(CDP)model in ABAQUS is used to simulate the behavior of concrete *** tensile behavior of anchors in geopolymer concrete is compared with that in normal concrete as well as that predicted by the linear fracture mechanics(LFM)and concrete capacity design(CCD)*** results show that the capacity of the anchors in geopolymer concrete is 30%–40%lower than that in normal *** results also indicate that the CCD model overestimates the capacity of the anchors in geopolymer concrete,whereas the LFM model provides a much more conservative *** extent of the difference between the predictions by the numerical analysis and those of the above prediction models depends on the effective embedment depth of the anchor and the anchor head *** influence of concrete surface cracking on the capacity of the anchor is shown to depend on the location of the crack and the effective embedment *** influence of the anchor head profile on the tensile capacity of the anchors is found to be insignificant.

关键词： cast-in anchor concrete cone capacity geopolymer concrete head size surface crack anchor profile

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Presence of neodymium and gadolinium in cobalt ferrite lattice:Structural,magnetic and microwave features for electromagnetic wave absorbing

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Journal of Rare Earths 2020年第4期38卷 411-417页

作者： alireza Nikzad Roghaieh Parvizi Department of Physics College of SciencesYasouj UniversityYasouj75914-353Iran

In this work,neodymium substituted gadolinium-cobalt ferrite nanoparticles were synthesized by hydrothermal *** significant role of doping both the Nd3+and Gd3+ions to cobalt ferrite in manipulating the cation distribution and further in influencing structural and magnetic properties was experimentally studied and *** influence of Nd3+substitution was investigated with step of 0.02-0.1 into the optimized Gd-Co *** crystal structure formation and crystallite size were explored by X-ray diffraction analysis in which the crystallite size and lattice constant decrease with increasing the Nd3+*** microstructural properties were studied by field emission scanning electron microscopy and atomic force microscopy *** obtained structural and morphological results reveal that the substitution of Nd3+with more than 0.06 into the Gd-Co ferrites will change the material be havior and *** saturation magnetization and coercivity values were measured using a vibration sample magnetometer at room *** microwave absorption experiments demonstrate that the reflection loss properties enhance with increasing substitution of Nd3+cations in Gd-Co ferrite spinel *** research reports that the as-prepared Nd3+substituted Gd-Co ferrite compound stands as promising candidate for absorbing electromagnetic wave with a wider absorbing bandwidth of X-band.

关键词： Gd-Co nanoferrite Coercive field Microwave absorption Rare earths

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Full Non-Rigid Group and Symmetry of Dimethyltrichlorophosphorus

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Chinese Journal of Chemistry 2005年第7期23卷 829-834页

作者： ASHRAFI alireza DepartmentofMathematics FacultyofScienceUniversityofKashanKashanIran

In this work, a simple method is described, by means of which it is possible to calculate character tables for the symmetry group of molecules consisting of a number of NH 3 groups attached to a rigid framework. The full non‐rigid group (f‐NRG) of dimethyltrichlorophosphorus with the symmetry group D 3h was studied. It has been proven that it is a group of order 216 with 27 conjugacy classes and its character table computed. Finally, thePermutation‐Inversion group of this molecule was calculated.

关键词： dimethyltrichlorophosphorus full non‐rigid group character table

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The Aghajari (Upper Fars) Formation in the Folded Zagros Zone, Iran: Insights to Identify Facies, Architectural Elements, Fluvial Systems, Petrography and Provenance

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Acta Geologica Sinica(English Edition) 2013年第4期87卷 1019-1031页

作者： Mohammad SAHRAEYAN Mohammad bahrami Sayed Hassan HEJAZI Department of Geology Islamic Azad University Khorasgan (Esfahan) Branch Department of Geology Islamic Azad University Fars Science and Research Branch

The Aghajari Formation, called also the Upper Fars, develops throughout the Folded Zagros Zone and its thickness in the type section in southwest of Iran is 2966 meters. To analyze the sedimentary basin of this Formation, lithofacies, architectural elements and petrofacies of the related deposits in a section in southeast of Sarvestan in Fars Province of Iran with a thickness of 2221.45 meters were examined. Microscopically studying thin sections, the petrography and the occurrence of the deposits were determined. In this section, 16 lithofacies, 10 architectural elements and 2 sandstone petrofacies were identified. The lithofacies were divided into two major and minor groups, in which the major lithofacies consist of coarse-grained （Gh, Gp, Gt and Gm）, medium-grained （Sh, Sp, St, Sl, Sm, Sr and Ss and fine-grained ones （Fm, Fl and Fsm）, and the minor lithofacies were evaporative and mixed silisiclastic-carbonate. The identified architectural elements are CH, SB, GB, LA, DA, CR, CS, LV, LS, CH （FF） and FF. By combining evidences from facies analysis and architectural elements together, the Aghajari Formation was divided into three parts in which the related sedimentation environments, from top to bottom, are gravel, gravel-sand and fine-grained meandering river respectively. There have also been playas and shoreface in the lower part. Based on petrography, the sandstones of this formation were classified into two groups： litharenite and sublitharenite. The origin of these deposits （sandstones） was appointed to the recycled orogeny and the source of quartz is low and medium to high metamorphic rank. Using the field evidences, the paleocurrent direction was achieved indicating the direction of the paleocurrent from northwest to southeast at the time of deposition. It is hoped that these data can be used in the interpretation of the basin and reconstruction of the paleogeography in the local and regional scales.

关键词： Aghajari Formation lithofacies architectural elements folded Zagros zone Iran,provenance

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Applications and verification of a computational energy dynamics model for mine climate simulations

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International Journal of Mining Science and Technology 2020年第4期30卷 483-493页

作者： G.Danko D.bahrami C.Stewart Department of Mining and Metallurgical Engineering University of NevadaRenoNV 89557USA School of Mechanical Engineering University of QueenslandQueensland 4072Australia

A complete thermodynamic model is described for temperature and heat flow distribution simulation for ventilation networks in underground *** method is called the Computational Energy Dynamics(CED)model of the heat,mass,and energy *** Thermal and Humidity(TH)transport elements of the full model are described for advection,convection,and accumulation,encompassing heat capacity,radiation,latent heat for evaporation,and condensation in the airways,as well as variable heat conduction and accumulation in the rock *** thermal flywheel effect for time-dependent temperature field applications is included in the model solution.A CED model validation exercise is described,directly evaluating the iterated,minimized energy balance errors for the mechanical and thermal energy components for each network branch after a converged solution is determined.A simulation example relevant to mine safety and health is shown with the CED-TH model,demonstrating its capabilities in efficiency and accuracy in comparison with measurement results.

关键词： Mine climate simulation Dynamic heat flow model Coupled heat and moisture transport Computational energy dynamics Mine safety and health

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Evolutionary Algorithms for Controller Tuning of Tert-Amyl-Methyl-Ether Reactive Distillation

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Journal of Systems Science and Systems Engineering 2020年第3期29卷 325-343页

作者： alireza Behroozsarand David AWood Faculty of Chemical Engineering Urmia University of TechnologyUrmiaIran DWA Energy Limited LincolnUnited Kingdom

Efficient tuning of the coefficients used by proportional-integral-derivative(PID)controllers enhances their *** highly non-linear systems,optimization algorithms are required to make the PID controllers more responsive to *** production of tert-amyl-methyl-ether(TAME),an essential additive for gasoline,in reactive distillation columns integrates highly non-linear reaction and separation *** the other hand,TAME distillation is an azeotrope distillation process,therefore non-linearity of this process is more complex than that of conventional ***-controller tuning methods applying a genetic algorithm(GA)and a particle swarm optimization(PSO)algorithm are compared using a dynamic simulation that integrates the optimization algorithms with the HYSYS process *** PID controller response trends are analyzed following the introduction of a significant disturbance to the TAME reactive distillation column(i.e.,a ten percent change in the methanol feed temperature).The PSO PID controller tuning method that minimizes the integral of the absolute error(IAE)as its objective function significantly outperforms the GA tuning *** novel PID-tuning methodology developed has more extensive application potential.

关键词： TAME azeotropic reactive distillation PID-controller tuning particle swarm optimization genetic algorithm real-time controller optimization

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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

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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

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