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Dynamic characteristics of bubbling fluidization through recurrence rate analysis of pressure fluctuations

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Particuology 2013年第3期11卷 282-287页

作者： Hossein Sedighikamal reza Zarghami Multiphase Systems Department Oil and Gas Processing Centre of ExcellenceSchool of Chemical EngineeringCollege of EngineeringUniversity of Tehran

Pressure fluctuations signals of a lab-scale fiuidized bed （15 cm inner diameter and 2 m height） at different superficial gas velocities were measured. Recurrence plot （RP） and recurrence rate （RR）, and the simplest variable of recurrence quantification analysis （RQA） were used to analyze the pressure signals. Different patterns observed in RP reflect different dynamic behavior of the system under study. It was also found that the variance of RR （a2R） Could reveal the peak dominant frequencies （PDF） of different dynamic systems： completely periodic, completely stochastic, Lorenz system, and fluidized bed. The results were compared with power spectral density. Additionally, the diagram of σ^2RR provides a new technique for prediction of transition velocity from bubbling to turbulent fluidization regime.

关键词： Pressure fluctuations Fluidization Recurrence rate Peak dominant frequency Transition velocity Power spectral density

Nonlocal vibration analysis of circular double-layered graphene sheets resting on an elastic foundation subjected to thermal loading

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Acta Mechanica Sinica 2016年第5期32卷 841-853页

作者： reza Ansari Jalal Torabi Department of Mechanical Engineering University of Guilan

Based on the nonlocal elasticity theory, the vibration behavior of circular double-layered graphene sheets（DLGSs） resting on the Winkler- and Pasternak-type elastic foundations in a thermal environment is *** governing equation is derived on the basis of Eringen＇s nonlocal elasticity and the classical plate theory（CLPT）.The initial thermal loading is assumed to be due to a uniform temperature rise throughout the thickness direction. Using the generalized differential quadrature（GDQ）method and periodic differential operators in radial and circumferential directions, respectively, the governing equation is discretized. DLGSs with clamped and simply-supported boundary conditions are studied and the influence of van der Waals（vd W） interaction forces is taken into *** the numerical results, the effects of various parameters such as elastic medium coefficients, radius-to-thickness ratio,thermal loading and nonlocal parameter are examined on both in-phase and anti-phase natural frequencies. The results show that the thermal load and elastic foundation respectively decreases and increases the fundamental frequencies of DLGSs.

关键词： Circular DLGS Vibration Nonlocal theory Thermal environment Numerical solution

Effects of some Nitrogen Bases on the Oxygenation of Tetralin with Sodium Periodate Catalyzed by Manganese（Ⅲ）meso- Tetraphenylporphyrin as a Model Compound of Cytochrome P-450

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Chinese Journal of Chemistry 2007年第7期25卷 1031-1035页

作者： reza, Tayebee Department of Chemistry Sabzevar Teacher Training University Sabzevar 397 Iran

The effect of some nitrogen bases on the oxygenation of tetralin by sodium periodate, catalyzed by Mn（TPP）OAc, was evaluated. A series of eight bases, including imidazole, pyridine, and quinuclidine, was used. Binding of axial ligand to the four-coordinate Mn（Ⅲ）-center influenced the efficiency and selectivity of the catalytic oxygenation system.

关键词： nitrogen donor sodium periodate oxidation manganese porphyrin tetralin

Evaluation of the remaining lateral torsional buckling capacity in corroded steel members

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第11期11卷 887-897页

作者： Yasser SHARIFI reza RAHGOZAR Department of Civil Engineering Kerman University

Corrosion is one of the main causes of deterioration in steel structures. Loss of thickness in flanges and web of corroded steel beams leads to reduction in section properties which can reduce the lateral torsional buckling capacity of the member. In this paper, thickness loss data were compiled from four samples of corrosion damaged I-beams removed from a petro-chemical plant. Visual examination of the four corroded beams showed that they were corroded uniformly. To improve the accuracy of the results, a large number of measurements for surface roughness were taken for each beam, totally 770 values to obtain the average thickness of flanges and web of each beam. The data was used to develop a corrosion decay model in order to calculate the percentage remaining lateral torsional buckling capacity of long and short span beams which are laterally unrestrained. To estimate the percentage of remaining lateral torsional buckling capacity in the corroded damaged I-beams, the readily available minimum curves for different types of universal beams in conjunction with information on the thickness loss were used. The results can be used by practicing engineers for better estimation on the service life of deteriorated steel structures.

关键词： Corrosion Steel structures Lateral torsional buckling Beams

Exact Solutions of the Harry-Dym Equation

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Communications in Theoretical Physics 2011年第2期55卷 204-208页

作者： reza Mokhtari Department of Mathematical Sciences Isfahan University of Technology

The aim of this paper is to generate exact travelling wave solutions of the Harry-Dym equation through the methods of Adomian decomposition, He＇s variational iteration, direct integration, and power series. We show t... 详细信息

关键词： Harry-Dym equation exact travelling wave solution Adomian decomposition method variational iteration method direct integration method power series method

Developing a GIS-based rough fuzzy set granulation model to handle spatial uncertainty for hydrocarbon structure classification,case study:Fars domain,Iran

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Geo-Spatial Information Science 2022年第3期25卷 399-412页

作者： Sahand Seraj Mahmoud reza Delavar School of Surveying and Geospatial Engineering University of TehranTehranIran Center of Excellence in Geomatics Engineering in Disaster Management University of TehranTehranIran

It is well agreed that geologic risk occurs during hydrocarbon exploration because diverse uncertainties accompany the entire hydrocarbon system parameters such as the source rock,reservoir rock,trap and seal *** order to overcome such attributes with uncertainties,a number of soft computing methods are *** granules could be provided by the Rough Fuzzy Set Granulation(RFSG)with a thorough quality *** is capable of attribute reduction that has been claimed to be essential in investigating the hydrocarbon *** paper is an endeavor to recommend a Geospatial Information System(GIS)-based model with the aim of categorizing the hydrocarbon structures map consistent with the uncertainty range concepts of geologic risk in the rough fuzzy sets and granular *** model used the RFSG for the attribute reduction by a Decision Logic language(DLlanguage).The RFSG was employed in order to classify hydrocarbon structures according to geological risk and extract the fuzzy rules with a predefined range of *** order to assess the precisions of the fuzzy decisions on the hydrocarbon structure classification,the fuzzy entropy and fuzzy cross-entropy are *** proposed RFSG model applied for 62 structures as the training data,average fuzzy entropy has been calculated as 0.85,whereas the average fuzzy cross-entropy has been calculated *** it can be discerned,just seven structures had cross-entropies greater than 0.1,while three structures were larger than *** is implied that the precision of the proposed model is about 89%.The results yielded two reductions for the condition attributes and 11 fuzzy rules being filtered by the granular computing values.

关键词： Rough fuzzy set granular computing Geospatial Information Science(GIS) petroleum system hydrocarbon structure

Prediction of bed load sediments using different artificial neural network models

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Frontiers of Structural and Civil Engineering 2020年第2期14卷 374-386页

作者： reza ASHEGHI Seyed Abbas HOSSEINI Department of Civil Engineering Science and Research BranchIslamic Azad UniversityTehranIran

Modeling and prediction of bed loads is an important but difficult issue in river *** introduced empirical equations due to restricted applicability even in similar conditions provide different accuracies with each other and measured *** this paper,three different artificial neural networks(ANNs)including multilayer percepterons,radial based function(RBF),and generalized feed forward neural network using five dominant parameters of bed load transport formulas for the Main Fork Red River in Idaho-USA were *** optimum models were found through 102 data sets of flow discharge,flow velocity,water surface slopes,flow depth,and mean grain *** deficiency of empirical equations for this river by conducted comparison between measured and predicted values was approved where the ANN models presented more consistence and closer estimation to observed *** coefficient of determination between measured and predicted values for empirical equations varied from 0.10 to 0.21 against the 0.93 to 0.98 in ANN *** accuracy performance of all models was evaluated and interpreted using different statistical error criteria,analytical graphs and confusion *** the ANN models predicted compatible outputs but the RBF with 79%correct classification rate corresponding to 0.191 nctwork error was outperform than others.

关键词： bed load prediction artificial neural network modeling empirical equations

Optimal design of double-layer barrel vaults using genetic and pattern search algorithms and optimized neural network as surrogate model

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Frontiers of Structural and Civil Engineering 2023年第3期17卷 378-395页

作者： reza JAVANMARDI Behrouz AHMADI-NEDUSHAN Department of Civil Engineering Yazd UniversityYazd 89195Iran

This paper presents a combined method based on optimized neural networks and optimization algorithms to solve structural optimization *** main idea is to utilize an optimized artificial neural network(OANN)as a surrogate model to reduce the number of computations for structural ***,the OANN is trained ***,the main optimization problem is solved using the OANN and a population-based *** algorithms considered in this step are the arithmetic optimization algorithm(AOA)and genetic algorithm(GA).Finally,the abovementioned problem is solved using the optimal point obtained from the previous step and the pattern search(PS)*** evaluate the performance of the proposed method,two numerical examples are *** the first example,the performance of two algorithms,OANN+AOA+PS and OANN+GA+PS,is *** the GA reduces the elapsed time by approximately 50%compared with using the *** show that both the OANN+GA+PS and OANN+AOA+PS algorithms perform well in solving structural optimization problems and achieve the same optimal ***,the OANN+GA+PS algorithm requires significantly fewer function evaluations to achieve the same accuracy as the OANN+AOA+PS algorithm.

关键词： optimization surrogate models artificial neural network SAP2000 genetic algorithm

Investigation of parameters influencing erosive wear using DEM

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Friction 2020年第1期8卷 136-150页

作者： Akbar JAFARI reza ABBASI HATTANI Department of Mechanical Engineering Sirjan University of TechnologySirjan ***Iran

The effects of several parameters on the erosive wear were studied using the discrete element method(DEM).The Finnie model was implemented using an open‐source *** the time integration,the Gear algorithm was used,and to ensure the accuracy of the DEM results,a time‐step sensitivity analysis was *** problem was modeled in two parts:first,the impact of a single particle on a surface was modeled,and then a more general model was prepared to examine the wear of surfaces under the flow of *** effects of the surface area,impact angle,speed,particle size,particle density,Young’s modulus,Poisson’s ratio,and restitution coefficient on the wear were studied numerically,and the results are discussed herein.

关键词： wear erosion Finnie discrete element