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Association Schemes with at Most Two Nonlinear Irreducible Characters and Applications to Finite Groups

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Acta Mathematica Sinica,English Series 2019年第4期35卷 481-493页

作者： javad BAGHERIAN Department of Mathematics University of Isfahan

An irreducible character χ of an association scheme is called nonlinear if the multiplicity of χ is greater than 1. The main result of this paper gives a characterization of commutative association schemes with at most two nonlinear irreducible characters. This yields a characterization of finite groups with at most two nonlinear irreducible characters. A class of noncommutative association schemes with at most two nonlinear irreducible character is also given.

关键词： Association scheme character finite group group-like scheme multiplicity nonlinear

Ocean Chemistry Revealed by Mineralogical and Geochemical Evidence at the Permian——Triassic Mass Extinction,Offshore the Persian Gulf,Iran

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Acta Geologica Sinica(English Edition) 2016年第5期90卷 1852-1864页

作者： vahid TAVAKOLI School of Geology College of ScienceUniversity of Tehran

The Upper Permian Dalan Formation and the Lower Triassic Kangan Formation in the Persian Gulf area are mainly composed of shallow marine facies limestone and *** subsurface-cored intervals were investigated in order to understand the original mineralogy and paleoceanic *** decreasing trend of Sr concentration in these deposits shows that aragonite was precipitated during the Late Permian and then gradually changed to calcite toward the Permian-Triassic boundary（PTB）.The dissolution rate of aragonite decreased from 60 m below the PTB toward the boundary,with the only exception at 10 m below the Permian-Triassic Boundary（PTB） due to the Permian-Triassic unconformity in this *** increasing trend of Mg/Ca ratio in a global scale at the end-Permian time shows that the interpreted variation of mineralogy does not result from the change of this *** increasing p（CO2） and decreasing pH are considered to be the main controlling *** increase of Ca2＋ at the end-Permian time due to the input of meteoric waters is too little to fully compensate this effect.A local maximum of the Si content just at the PTB confirms the input of runoff waters.

关键词： Permian Triassic carbonate mineralogy elemental composition Iran Persian Gulf

Advances and opportunities in wind energy harvesting using plasma actuators:a review

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Clean Energy 2024年第1期8卷 197-225页

作者： javad Omidi Department of Chemical Engineering Columbia UniversityNew YorkNYUSA

The dielectric barrier discharge plasma actuator has been recognized as a leading technology for controlling fluid flow and has found remarkable applications in wind energy harvesting over the past *** turbine aerodynamics are critical in this concept and performance is mainly determined by flow controllers,although significant technical progress is still *** paper examines all the critical studies to investigate the potential application of plasma actuators for airflow control over wind *** approach has been divided into three categories:wind turbine airfoils,horizontal-axis wind turbines and vertical-axis wind turbines aerodynamic performance and generated ***,the potential functions of plasma actuators in current and future wind turbine generators are *** actuators offer promising solutions to increasing power output,minimizing torque fluctuations and enabling self-starting capabilities,particularly in vertical-axis wind *** adjusting blade pitch angles in conjunction with plasma actuators,significant improvements in airflow optimization and power extraction have been *** the advancements,challenges persist,such as determining optimal actuator placement and overcoming structural limitations,especially concerning 3D effects and high Reynolds *** plasma actuators enhance aerodynamic efficiency,their complexity needs to be balanced against marginal gains in power production,especially in high-megawatt turbines,for which controlling flow at low wind speeds is *** research must focus on the sustainable integration of plasma actuators,pitch angle adjustments and active control mechanisms to fully exploit the potential of wind energy for a sustainable future.

关键词： plasma actuator wind turbine aerodynamic performance generated power

Effects of foundation rocking and uplifting on displacement amplification factor

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Earthquake Engineering and Engineering Vibration 2018年第3期17卷 511-525页

作者： Mohammad Khanmohammadi vahid Mohsenzadeh School of Civil Engineering University of Tehran Department of Civil Engineering Mc Master University

Prediction of displacement demand to assess seismic performance of structures is a necessary step where nonlinear static procedures are *** such predictions have been well established in literature for fixed-base structures,fewer bodies of researches have been carried out on the effect of rocking and uplifting of shallow foundations supported by soil,on such *** paper aimed to investigate the effect of soil structure interaction on displacement amplification factor C1 using the beam on nonlinear Winkler foundation concept.A practical range of natural period,force reduction factors,and wide range of anticipated behavior from rocking,uplifting and hinging are considered and using thousands nonlinear time history analysis,displacement amplification factors are *** results indicate that the suggested equations in current rehabilitation documents underestimate displacement demands in the presence of foundation rocking and ***,using regression analyses,new equations are proposed to estimate mean values of C1.

关键词： soil-structure interaction rocking and uplifting foundations displacement amplification factor

Dielectric microspheres enhance microscopy resolution mainly due to increasing the effective numerical aperture

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Light(Science & Applications) 2023年第1期12卷 17-19页

作者： Arash Darafsheh vahid Abbasian Department of Radiation Oncology Washington University School of Medicine in St.LouisSt.LouisMO 63110USA

Microsphere-assisted microscopy utilizing a microsphere in immediate proximity of the specimen boosts the imaging resolution mainly as a result of an increase in the effective numerical aperture of the system.

关键词： resolution numerical utilizing

Statistical evaluation and optimization of zinc electrolyte hot purification process by Taguchi method

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Journal of Central South University 2015年第6期22卷 2066-2072页

作者： Bahram Behnajady javad Moghaddam Materials and Metallurgical Engineering Department Advanced Material Research CentreSahand University of Technology Tabriz

The neutral zinc sulfate solution obtained from hydrometallurgical process of Angouran zinc concentrate has cadmium, nickel and cobalt impurities, that must be purified before electrowinning. Therefore, cadmium and nickel are usually cemented out by addition of zinc dust and remained nickel and cobalt cemented out at second stage with zinc powder and arsenic trioxide. In this research, a new approach is described for determination of effective parameters and optimization of zinc electrolyte hot purification process using statistical design of experiments. The Taguchi method based on orthogonal array design（OAD） has been used to arrange the experimental runs. The experimental conditions involved in the work are as follows： the temperature range of 70-90 ℃ for reaction temperature（T）, 30-90 min for reaction time（t）, 2-4 g/L for zinc powder mass concentration（M）, one to five series for zinc dust particle size distributions（S1-S5）, and 0.1-0.5 g/L（C） for arsenic trioxide mass concentration. Optimum conditions for hot purification obtained in this work are T4（85 ℃）, t4=75 min, M4=3.5 g/L, S4（Serie 4）, and C2=0.2 g/L.

关键词： taguchi method hot purification nickel cobalt arsenic trioxide

Preparation of NiO nanoparticles from Ni(OH)_2·NiCO_3·4H_2O precursor by mechanical activation

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International Journal of Minerals,Metallurgy and Materials 2014年第7期21卷 726-735页

作者： Kolsoom Ahmadisoltansaraei javad Moghaddam Materials and Metallurgical Engineering Department Advanced Materials Research CenterSahand University of Technology

A mechanical activation process was introduced as a facile method for producing nickel oxide nanopowders. The precursor compound Ni（OH）2-NiCO3-4H2O was synthesized by chemical precipitation. The precursor was milled with NaCl diluent. A high-energy ball milling process led to decomposition of the precursor and subsequent dispersal in NaCl media. Nickel oxide nanocrystalline powders were produced by subsequent heat treatment and water washing. Milling rotation speed, milling time, ball-to-powder ratio （BPR）, and nickel chlo-ride-to-precursor ratio were introduced as influential parameters on the wavelength of maximum absorption （λmax）. The effects of these pa-rameters were investigated by the Taguchi method. The optimum conditions for this study were a milling rotation speed of 150 r/min, a mill-ing time of 20 h, a BPR of 15/1, and a NaCl-to-powder weight ratio （NPR） of 6/1. In these conditions,λmax was predicted to be 292 nm. The structural properties of the samples were determined by field emission scanning electron microscopy, X-ray diffraction, and energy dispersive spectrometry.

关键词： nickel oxide nanoparticles chemical precipitation mechanical activation Taguchi method

Data driven models for compressive strength prediction of concrete at high temperatures

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Frontiers of Structural and Civil Engineering 2020年第2期14卷 311-321页

作者： Mahmood AKBARI vahid JAFARI DELIGANI Department of Civil Engineering Faculty of EngineeringUniversity of KashanKashan ***Iran

The use of data driven models has been shown to be useful for simulating complex engineering processes,when the only information available consists of the data of the *** this study,four data-driven models,namely multiple linear regression,artificial neural network,adaptive neural fuzzy inference system,and K nearest neighbor models based on collection of 207 laboratory tests,are investigated for compressive strength prediction of concrete at high *** addition for each model,two different sets of input variables are examined:a complete set and a parsimonious set of involved *** results obtained are compared with each other and also to the equations of NIST Technical Note standard and demonstrate the suitability of using the data driven models to predict the compressive strength at high *** addition,the results show employing the parsimonious set of input variables is sufficient for the data driven models to make satisfactory results.

关键词： data driven model compressive strength oncrete high temperature

Mechanical Properties and Microstructure Evolution of AA1100 Aluminum Sheet Processed by Accumulative Press Bonding Process

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Acta Metallurgica Sinica(English Letters) 2016年第8期29卷 735-741页

作者： Amir Mostafapor vahid Mohammadinia Department of Mechanical Engineering University of Tabriz Department of Mechanical Engineering University of Maragheh

Accumulative press bonding（APB） is a novel variant of severe plastic deformation processes,which is devised to produce materials with ultra-fine *** the present work,the mechanical properties and microstructural evolution of AA1100 alloy,which is produced by APB technique,were *** study of the microstructure of AA1100 alloy was performed by optical *** results revealed that the grain size of the samples decreased to 950 nm after six passes of APB *** yield strength of AA1100 alloy after six passes of the process increased up to 264 MPa,which is three times higher than that of the as-cast material（89 MPa）.After six passes,microhardness values of AA1100 alloy increased from 38 to 61 ***,the results showed that the behavior of variations in mechanical properties is in accordance with the microstructural changes and it can be justified by using the Hall-Patch ***,the rise in the yield strength can be attributed to the reduction in the grain size leading to the strain hardening.

关键词： Severe plastic deformation Accumulative press bonding Mechanical properties Metallurgical properties AA1100 alloy