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Frontiers of Structural and Civil Engineering 2020年第3期14卷 675-689页

作者： Iman FATTAHI hamid reza mirdamadi hamid ABDOLLAHI Department of Mechanical Engineering Isfahan University of TechnologyIsfahan ***Iran

Analyzing static and dynamic problems including composite structures has been of high significance in research efforts and industrial *** this article,equivalent single layer approach is utilized for dynamic finite element procedures of 3D composite beam as the building block of numerous composite *** this model,both displacement and strain fields are decomposed into cross-sectional and longitudinal components,called consistent geometric decomposition ***,the model is discretized using finite clement *** local coordinate systems and a global one are defined to decouple mechanical degrees of ***,from the viewpoint of consistent geometric decomposition theorem,the transformation and element mass matrices for those systems are introduced here for the first *** same decomposition idea can be used for developing element stiffiness ***,comprehensive validations are conducted for the theory against experimental and numerical results in two case studies and for various conditions.

关键词： composite beam dynamic finite element degrees of freedom coupling experimental validation numerical validation

Effect of metal oxide arrester on the chaotic oscillations in the voltage transformer with nonlinear core loss model using chaos theory

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Chinese Physics B 2014年第1期23卷 480-488页

作者： hamid reza Abbasi habbasi@iust.ac.ir Amirkabir University Electrical Engineering Department Tehran 64540 Iran

In this paper, controlling chaos when chaotic ferroresonant oscillations occur in a voltage transformer with nonlin- ear core loss model is performed. The effect of a parallel metal oxide surge arrester on the ferroresonance oscillations of voltage transformers is studied. The metal oxide arrester （MOA） is found to be effective in reducing ferroresonance chaotic oscillations. Also the multiple scales method is used to analyze the chaotic behavior and different types of fixed points in ferroresonance of voltage transformers considering core loss. This phenomenon has nonlinear chaotic dynamics and includes sub-harmonic, quasi-periodic, and also chaotic oscillations. In this paper, the chaotic behavior and various ferroresonant oscillation modes of the voltage transformer is studied. This phenomenon consists of different types of bifur- cations such as period doubling bifurcation （PDB）, saddle node bifurcation （SNB）, Hopf bifurcation （HB）, and chaos. The dynamic analysis of ferroresonant circuit is based on bifurcation theory. The bifurcation and phase plane diagrams are il- lustrated using a continuous method and linear and nonlinear models of core loss. To analyze ferroresonance phenomenon, the Lyapunov exponents are calculated via the multiple scales method to obtain Feigenbaum numbers. The bifurcation diagrams illustrate the variation of the control parameter. Therefore, the chaos is created and increased in the system.

关键词： ferroresonance chaos theory metal oxide arrester Lyapunov exponent

Numerical and experimental study of an innovative pipeline design in a granular pneumatic-conveying system

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Particuology 2018年第3期16卷 196-203页

作者： Hasan Ghafori hamid reza Ebrahimi Department of Mechanical Engineering MaJlesi Branch Islamic Azad University lsfilhan Iran Department of Chemical Engineering Majlesi Branch Islamic Azad University lsfahan Iran

During gas-solid mixture conveying in a dense phase, material is conveyed in dunes on the bottom of the pipeline, or as a pulsating moving bed. This phenomenon increases the pressure drop and power consumption. We introduce a new technique to reduce the pressure drop, which is termed the perforated double tube. To validate this new model, the gas-solid flow pattern and pressure drop were studied numerically and experimentally. The power consumption was also studied experimentally. Numerical studies were performed by the Eulerian-Lagrangian approach to predict gas and particle movement in the pipeline, Comparisons between the numerical predictions and the experimental results for the gas-solid flow patterns and pressure drop show good agreement.

关键词： Computational fluid dynamics Power consumption Perforated double tube Pneumatic conveying

Preparation of La-Mo-V mixed-oxide systems and their application in the direct synthesis of acetic acid

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Journal of Natural Gas Chemistry 2008年第3期17卷 213-224页

作者： hamid reza Arandiyan Matin Parvari Chemical Engineering Department Iran University of Science and Technology

In this study, mixed metal oxides developed with a perovskite-type structure that show great potential for use in catalysis. Perovskite oxide catalysts with the composition LaMoxV1-xOn （x = 0.1, 0.3, 0.5, 0.7, and 0.9） have been synthesized by the sol-gel method and then used in the ethane dry reforming reaction for the direct synthesis of acetic acid. The influence of the nature of the metallic source （metal, nitrate, acetylacetonate, and ammonium） on gel formation has been studied by Fourier-transform infrared spectroscopy （FT-IR） and thermogravimetric analysis （TGA-DTA）. After calcination, the obtained perovskites were characterized by X-ray diffraction （XRD） and energy-dispersive X-ray spectrometry （EDS） coupled with scanning electron microscopy （SEM）. The catalysts were then subjected to thermo-programmed reduction （TPR）. The surface area （BET） was found to increase from 2.6 m^2/g （x = 0.1） to 5.1 m2/g （x = 1.0） with increasing molybdenum content following calcinations at 750 °C, and pure LaMoxV1-xOn perovskite was obtained with good homogeneity. The catalysts have been characterized by XRD, SEM, EDS, and carbon analysis （CA）. The results indicate that through this synthesis it is possible to obtain highly crystalline, homogeneous and pure solids, with well-defined structures. The direct synthesis of acetic acid from ethane over the perovskite catalysts was studied at temperatures between 450 and 850 °C and elevated pressures between 1 and 8 bar. It was found that the yield of acetic acid and the selectivity of its formation could be increased by incorporating more molybdenum into the perovskite structure. The experimental studies have shown that the calcination temperature and the molybdenum content have a significant influence on the catalytic activity. Amongst the catalysts tested, LaMo0.7V0.3O4.2 exhibited the best activity and stability.

关键词： acetic acid catalyst perovskite activity LaMoxV1-xOn

Generating one-,two-,three-and four-scroll attractors from a novel four-dimensional smooth autonomous chaotic system

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Chinese Physics B 2010年第6期19卷 106-114页

作者： Sara Dadras hamid reza Momeni Automation and Instruments Lab Electrical Engineering DepartmentTarbiat Modares UniversityP.O.Box 14115-143TehranIran

A new four-dimensional quadratic smooth autonomous chaotic system is presented in this paper, which can exhibit periodic orbit and chaos under the conditions on the system parameters. Importantly, the system can generate one-, two-, three- and four-scroll chaotic attractors with appropriate choices of parameters. Interestingly, all the attractors are generated only by changing a single parameter. The dynamic analysis approach in the paper involves time series, phase portraits, Poincare maps, a bifurcation diagram, and Lyapunov exponents, to investigate some basic dynamical behaviours of the proposed four-dimensional system.

关键词： new smooth autonomous four-dimensional chaotic system multi-scroll chaotic attractor Poincare mapping bifurcation Lyapunov exponent

Aircraft robust multidisciplinary design optimization methodology based on fuzzy preference function

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Chinese Journal of Aeronautics 2018年第12期31卷 2248-2259页

作者： Ali reza BABAEI Mohammad reza SETAYANDEH hamid FARROKHFAL Department of Mechanical and Aerospace Engineering Malek-Ashtar University of Technology

This paper presents a Fuzzy Preference Function-based Robust Multidisciplinary Design Optimization(FPF-RMDO) methodology. This method is an effective approach to multidisciplinary systems, which can be used to designer experiences during the design optimization process by fuzzy preference functions. In this study, two optimizations are done for Predator MQ-1 Unmanned Aerial Vehicle(UAV):(A) deterministic optimization and(B) robust optimization. In both problems, minimization of takeoff weight and drag is considered as objective functions, which have been optimized using Non-dominated Sorting Genetic Algorithm(NSGA). In the robust design optimization, cruise altitude and velocity are considered as uncertainties that are modeled by the Monte Carlo Simulation(MCS) method. Aerodynamics, stability and control, mass properties, performance, and center of gravity are used for multidisciplinary analysis. Robust design optimization results show 46% and 42% robustness improvement for takeoff weight and cruise drag relative to optimal design respectively.

关键词： Fuzzy logic Multidisciplinary design optimization Preference function Robust design Unmanned Aerial Vehicle(UAV)

Frequency-domain generelaized singular peruturbation method for relative error model order reduction

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控制理论与应用（英文版） 2009年第1期7卷 57-62页

作者： hamid reza SHAKER Section for Automation and Control Institute for Electronic SystemsAalborg University

A new mixed method for relative error model order reduction is proposed. In the proposed method the frequency domain balanced stochastic truncation method is improved by applying the generalized singular perturbation method to the frequency domain balanced system in the reduction procedure. The frequency domain balanced stochastic truncation method, which was proposed in [15] and [17] by the author, is based on two recently developed methods, namely frequency domain balanced truncation within a desired frequency bound and inner-outer factorization techniques. The proposed method in ttiis paper is a carry over of the frequency-domain balanced stochastic truncation and is of interest for practical model order reduction because in this context it shows to keep the accuracy of the approximation as high as possible without sacrificing the computational efficiency and important system properties. It is shown that some important properties of the frequency domain stochastic balanced reduction technique are extended to the proposed reduction method by using the concept and properties of the reciprocal systems. Numerical results show the accuracy, simplicity and flexibility enhancement of the method.

关键词： Large-scale systems Model reduction Balanced realization Frequency-domain Grammian

Modeling the oxidative coupling of methane: Heterogeneous chemistry coupled with 3D flow field simulation

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Journal of Natural Gas Chemistry 2009年第1期18卷 39-44页

作者： Yaghobi Nakisa Ghoreishy Mir hamid reza Iran Polymer and Petrochemical Institute P. O. Box 14965/115 Tehran Iran

The oxidative coupling of methane （OCM） over titanate perovskite catalyst has been developed by three-dimensional numerical simulations of flow field coupled with heat transfer as well as heterogeneous kinetic model. The reaction was assumed to take place both in the gas phase and on the catalytic surface. Kinetic rate constants were experimentally obtained using a ten step kinetic model. The simulation results agree quite well with the data of OCM experiments, which were used to investigate the effect of temperature on the selectivity and conversion obtained in the methane oxidative coupling process. The conversion of methane linearly increased with temperature and the selectivity of C2 was practically constant in the temperature range of 973-1073 K. The study shows that CFD tools make it possible to implement the heterogeneous kinetic model even for high exothermic reaction such as OCM.

关键词： OCM simulation kinetics fixed bed catalytic reactor ethylene

Influences of adsorptions of some inorganic molecules on electronic, optical, and thermodynamic properties of Mg_(12)O_(12) nanocage: A computational approach

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Chinese Physics B 2018年第8期27卷 280-289页

作者： Asghar Mohammadi Hesari hamid reza Shamlouei Chemistry Department Lorestan UniversityI(horram AbadLorestanIraa

According to density functional theory, we investigate the effects of BF3, BF4, BCI3, A1F3, AICI3, A1Br3, 13eF3, GaF3, GaC13, GaBr3, NO3, BS2, BSO, BO2, F2, PFs, PC15, and ASF5 molecules on the geometric, electronic, linear, and nonlinear optical properties of an Mg12012 nanocage. The thermodynamic stability and feasibility of the adsorption process are investigated by analyzing the free energy. It is shown that the adsorptions of almost all molecules on the Mg12OI2 surface are exothermic. The calculations of the polarizability of these nanoclusters show that among the studied molecules, BeF3 has the largest influence on the polarizability value （a≈315 a.u., the unit a.u. is short for atomic unit）. The static first hyperpolarizability （β0） value is increased in the presence of these superhalogens. This increase is greatest for BeF3 and BF4 of which the highest value of the first hyperpolarizability （βO≈ 5775 a.u.） is related to a BeF3_c（e@Mgl2Ol2） nanocluster. The adsorption position is a key to estimating the value of increasing the first hyperpolarizability.

关键词： Mg1201 polarizability hyperpolarizability binding energy nanocage DFT calculation

How do machine learning techniques help in increasing accuracy of landslide susceptibility maps?

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Geoscience Frontiers 2020年第3期11卷 871-883页

作者： Yacine Achour hamid reza Pourghasemi Department of Civil Engineering Bordj Bou Arreridj University34030El AnnasserAlgeria Department of Natural Resources and Environmental Engineering College of AgricultureShiraz UniversityShirazIran

Landslides are abundant in mountainous *** are responsible for substantial damages and losses in those *** A1 Highway,which is an important road in Algeria,was sometimes constructed in mountainous and/or semi-mountainous *** studies of landslide susceptibility mapping conducted near this road using statistical and expert methods have yielded ordinary *** this research,we are interested in how do machine learning techniques help in increasing accuracy of landslide susceptibility maps in the vicinity of the A1 Highway *** do this,an important section at Ain Bouziane(NE,Algeria) is chosen as a case study to evaluate the landslide susceptibility using three different machine learning methods,namely,random forest(RF),support vector machine(SVM),and boosted regression tree(BRT).First,an inventory map and nine input factors were prepared for landslide susceptibility mapping(LSM) *** three models were constructed to find the most susceptible areas to this *** results were assessed by calculating the receiver operating characteristic(ROC) curve,the standard error(***),and the confidence interval(CI) at 95%.The RF model reached the highest predictive accuracy(AUC=97.2%) comparatively to the other *** outcomes of this research proved that the obtained machine learning models had the ability to predict future landslide locations in this important road *** addition,their application gives an improvement of the accuracy of LSMs near the road *** machine learning models may become an important prediction tool that will identify landslide alleviation actions.

关键词： Spatial modelling Support vector machine Random forest Boosted regression tree Validation measures Algeria