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Comparative orotomy of the Archean Superior and Phanerozoic Altaid orogenic systems

National Science review 2023年第2期10卷 20-48页

作者： Timothy m.Kusky A.m.Celal ?eng?r Center for Global Tectonics School of Earth Sciences and State Key Laboratory for Geological Processes and Mineral ResourcesChina University of Geosciences Badong National Observatory and research Station for Geohazards Ministry of Education China University of Geosciences Department of Geological Engineering Middle East Technical University Eurasia Institute of Earth Sciences Istanbul Technical University Department of Geology Faculty of Mines Istanbul Technical University

We compare and contrast the materials and mechanisms of continental crustal growth in the largest preserved regions of Phanerozoic and Archean juvenile additions to the crust,to test for similarities or differences in the formation of continents through time.We accomplish this through a comparison of map patterns,lithological contents,and structural and metamorphic evolution of the Phanerozoic Altaid orogenic system of Asia,with the Archean Superior Province of the North American Craton,using a method termed comparative orotomy.Both orogenic systems consist of collages of curvilinear belts of eroded arcs,some older continental slivers,and vast tracts of former subduction/accretionary complexes.These contain numerous shreds of portions of the ophiolite suite,slivers of island and continental arcs,and accreted oceanic plateau,all intruded by multiple magmatic suites during or between multiple deformation events,then sliced by large transcurrent fault systems and bent into large oroclinal structures.We make this comparison because the Superior Province is a typical Archean craton that was later,in the P aleoproterozoic,incorporated into the larger North American Craton,and has occupied a central position in several super continents(e.g.Kenorland and Nuna,which then formed the core of Columbia,rodinia,Laurentia and Pangea) during its longevity.Since it is the largest single fragment of Archean continental cratonic lithosphere preserved on Earth,the Superior Province is widely regarded as a testing ground for how Earth’s continental crust was formed.Likewise,the Altaids encompass the largest region of crustal growth for the Phanerozoic.Our comparison with the Altaids is needed,as in recent years many myths about how the planet may have responded to higher heat production and flow in the Archean have emerged,because of trends in the science where regional geology is ignored in favor of numerical models,isotopic proxies for assumed models of chemical behavior for crust-forming or tectonic processes,or comparisons with o

关键词： Altaids superior province ophiolite subduction strike-slip

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Effects of viscoelasticity on the stability and bifurcations of nonlinear energy sinks

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Applied mathematics and mechanics(English Edition) 2023年第1期44卷 141-158页

作者： A.mOSLEmI m.r.HOmAEINEZHAD Faculty of mechanical Engineering K.N.Toosi University of TechnologyTehran ***Iran

Due to the increasing use of passive absorbers to control unwanted vibrations,many studies have been done on energy absorbers ideally,but the lack of studies of real environmental conditions on these absorbers is felt.The present work investigates the effect of viscoelasticity on the stability and bifurcations of a system attached to a nonlinear energy sink(NES).In this paper,the Burgers model is assumed for the viscoelasticity in an NES,and a linear oscillator system is considered for investigating the instabilities and bifurcations.The equations of motion of the coupled system are solved by using the harmonic balance and pseudo-arc-length continuation methods.The results show that the viscoelasticity affects the frequency intervals of the Hopf and saddle-node branches,and by increasing the stiffness parameters of the viscoelasticity,the conditions of these branches occur in larger ranges of the external force amplitudes,and also reduce the frequency range of the branches.In addition,increasing the viscoelastic damping parameter has the potential to completely eliminate the instability of the system and gradually reduce the amplitude of the jump phenomenon.

关键词： viscoelasticity Burgers model nonlinear energy sink(NES) saddle-node bifurcation Hopf bifurcation

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Kinematic analysis of flexible bipedal robotic systems

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Applied mathematics and mechanics(English Edition) 2024年第5期45卷 795-818页

作者： r.FAZEL A.m.SHAFEI S.r.NEKOO Department of mechanical Engineering Shahid Bahonar University of KermanKerman ***Iran Departamento de Ingenieria de Sistemas y Automatica Escuela Técnica Superior de IngenieriaUniversidad de SevillaSeville 41092Spain

In spite of its intrinsic complexities,the passive gait of bipedal robots on a sloping ramp is a subject of interest for numerous researchers.What distinguishes the present research from similar works is the consideration of flexibility in the constituent links of this type of robotic systems.This is not a far-fetched assumption because in the transient(impact)phase,due to the impulsive forces which are applied to the system,the likelihood of exciting the vibration modes increases considerably.moreover,the human leg bones that are involved in walking are supported by viscoelastic muscles and ligaments.Therefore,for achieving more exact results,it is essential to model the robot links with viscoelastic properties.To this end,the Gibbs-Appell formulation and Newton's kinematic impact law are used to derive the most general form of the system's dynamic equations in the swing and transient phases of motion.The most important issue in the passive walking motion of bipedal robots is the determination of the initial robot configuration with which the system could accomplish a periodic and stable gait solely under the effect of gravitational force.The extremely unstable nature of the system studied in this paper and the vibrations caused by the impulsive forces induced by the impact of robot feet with the inclined surface are some of the very serious challenges encountered for achieving the above-mentioned goal.To overcome such challenges,an innovative method that uses a combination of the linearized equations of motion in the swing phase and the algebraic motion equations in the transition phase is presented in this paper to obtain an eigenvalue problem.By solving this problem,the suitable initial conditions that are necessary for the passive gait of this bipedal robot on a sloping surface are determined.The effects of the characteristic parameters of elastic links including the modulus of elasticity and the Kelvin-Voigt coefficient on the walking stability of this type of robotic systems are also studied.The findings o

关键词： bipedal robot flexible link swing phase transient phase eigenvalue problem Kelvin-Voigt coefficient

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Control system design for a pressure-tube-type supercritical water-cooled nuclear reactor via a higher order sliding mode method

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Nuclear Science and Techniques 2024年第1期35卷 145-154页

作者： m.Hajipour G.r.Ansarifar Department of Nuclear Engineering Faculty of PhysicsUniversity of IsfahanIsfahan 81746-73441Iran

Nuclear power plants exhibit non-linear and time-variable dynamics.Therefore,designing a control system that sets the reactor power and forces it to follow the desired load is complicated.A supercritical water reactor(SCWr)is a fourth-generation conceptual reactor.In an SCWr,the non-linear dynamics of the reactor require a controller capable of control-ling the nonlinearities.In this study,a pressure-tube-type SCWr was controlled during reactor power maneuvering with a higher order sliding mode,and the reactor outgoing steam temperature and pressure were controlled simultaneously.In an SCWr,the temperature,pressure,and power must be maintained at a setpoint(desired value)during power maneuvering.reactor point kinetics equations with three groups of delayed neutrons were used in the simulation.Higher-order and classic sliding mode controllers were separately manufactured to control the plant and were compared with the PI controllers speci-fied in previous studies.The controlled parameters were reactor power,steam temperature,and pressure.Notably,for these parameters,the PI controller had certain instabilities in the presence of disturbances.The classic sliding mode controller had a higher accuracy and stability;however its main drawback was the chattering phenomenon.HOSmC was highly accurate and stable and had a small computational cost.In reality,it followed the desired values without oscillations and chattering.

关键词： Supercritical water nuclear reactor Higher order sliding mode controller Steam temperature Steam pressure Point kinetics model

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Numerical Solution of Partial Differential Equations in Arbitrary Shaped Domains Using Cartesian Cut-Stencil Finite Difference method.Part II:Higher-Order Schemes

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Numerical mathematics(Theory,methods and Applications) 2022年第3期15卷 819-850页

作者： m.Esmaeilzadeh r.m.Barron Department of mechanical Automotive&Materials EngineeringUniversity of WindsorWindsorOntarioN9B 3P4Canada Department of mathematics&Statistics University of WindsorWindsorOntarioN9B 3P4Canada Department of mechanical Engineering South Tehran BranchIslamic Azad UniversityTehranP.C:***Iran

Compact higher-order(HO)schemes for a new finite difference method,referred to as the Cartesian cut-stencil FD method,for the numerical solution of the convection-diffusion equation in complex shaped domains have been addressed in this paper.The Cartesian cut-stencil FD method,which employs 1-D quadratic transformation functions to map a non-uniform(uncut or cut)physical stencil to a uniform computational stencil,can be combined with compact HO Pad´e-Hermitian formulations to produce HO cut-stencil schemes.The modified partial differential equation technique is used to develop formulas for the local truncation error for the cut-stencil HO formulations.The effect of various HO approximations for Neumann boundary conditions on the solution accuracy and global order of convergence are discussed.The numerical results for second-order and compact HO formulations of the Cartesian cut-stencil FD method have been compared for test problems using the method of manufactured solutions.

关键词： Cartesian cut-stencil finite difference method compact higher-order formulation irregular domain Neumann boundary conditions local truncation error

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冷轧及退火对310S奥氏体不锈钢的微观结构和组织的影响:基于X射线和电子背散射衍射分析

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Journal of Central South University 2023年第3期30卷 763-785页

作者： r.B.HEIDArI m.ESKANDArI m.YEGANEH Department of materials Engineering Faculty of EngineeringShahid Chamran University of AhvazAhvaz ***Iran

本文研究了热处理对310S奥氏体不锈钢的微观结构和组织的影响。对样品材料进行冷轧,使其厚度分别减少20%、50%和90%,然后在1023、1223和1323 K下退火5、15和30 min。在厚度减少20%后,奥氏体内产生孪晶,且可观察到形变诱发的α’马氏体,... 详细信息

本文研究了热处理对310S奥氏体不锈钢的微观结构和组织的影响。对样品材料进行冷轧,使其厚度分别减少20%、50%和90%,然后在1023、1223和1323 K下退火5、15和30 min。在厚度减少20%后,奥氏体内产生孪晶,且可观察到形变诱发的α’马氏体,孪晶的体积分数大于α’马氏体。当厚度变化由50%增加到90%,α’马氏体的体积分数由11%增加到69%,孪晶被α’马氏体取代。发生形变后奥氏体相主要为Brass、Goss和S织构,α’马氏体的主要纹理为r-Cu、r-cube、F和E组份。随着形变量增大,Brass织构增加,Goss织构减少。退火过程中,马氏体向奥氏体转变,并发生了再结晶,使Goss和Brass再结晶织构的体积分数增加。材料退火后的结构与冷轧后的大致相同。1223 K下退火5 min的马氏体转变速度明显高于1023 K下的。在1023 K下退火5 min,由于马氏体不完全转变和初级再结晶,未能检测到等轴组织。获得超细晶粒组织的最佳退火温度为1023 K,退火时间为15 min。在1173 K和1273 K时出现快速再结晶和晶粒生长。

关键词： 310S不锈钢形变退火电子背散射衍射微观结构组织

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Energy-based damage assessment of continuous-span reinforced concrete highway bridges

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Earthquake Engineering and Engineering Vibration 2023年第1期22卷 191-209页

作者： S.mahboubi m.r.Shiravand Faculty of Civil Water and Environmental EngineeringShahid Beheshti UniversityTehran ***Iran

This paper conducts a comparative study on seismic damage to reinforced concrete(rC)bridges,using three damage models:Park and Ang,Hindi and Sexsmith,and input energy-based damage(IEBD)indices,and presents a global cumulative damage model based on the IEBD index to establish a practical damage assessment of an overall bridge system.A series of rC bridges are studied under seismic loadings,and to compare the efficiency and reliability of the damage indices,damage curves of rC piers are developed,and damage levels of piers are calculated at design basis earthquake(DBE)and maximum considered earthquake(mCE)levels.The global cumulative damage index is calculated for bridge models regarding damage values of components.The results indicate that the IEBD index shows a gradual progression of damage and provides reasonable values for different damage levels of piers compared to two other damage indices.moreover,the global cumulative damage index shows the impact of induced damage to a certain component regarding the damage level of the overall bridge system.moreover,this new approach is a relatively simple and practical tool for seismic damage assessment of rC bridge systems,which can be implemented in finite element models,particularly in the absence of experimental data.

关键词： rC bridge energy-based damage index global cumulative damage index IEBD Index

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microstructure refinement,mechanical and biocorrosion properties of mg–Zn–Ca–mn alloy improved by a new severe plastic deformation process

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Journal of magnesium and Alloys 2022年第6期10卷 1640-1662页

作者： m.Kavyani G.r.Ebrahimi H.r.Ezatpour m.Jahazi materials and metallurgical Engineering Department Faculty of EngineeringFerdowsi University of MashhadMashhad ***Iran Faculty of Engineering Sabzevar University of New TechnologySabzevarIran Department of mechanical Engineering École de Technologie SupérieureMontréalPQCanada

In this study,the microstructural evolution,mechanical properties and biocorrosion performance of a mg–Zn–Ca–mn alloy were investigated under different conditions of heat treatment,extrusion,one pass and two passes of half equal channel angular pressing(HECAP)process.The results showed significant grain refinement of the homogenized alloy after two passes of HECAP process from 345μm to 2μm.Field emission scanning electron microscopy(FESEm)revealed the presence of finer mg_(6)Zn_(3)Ca_(2)phase as well asα-mn phase after HECAP process.The results also showed that mechanical characteristics such as yield strength,ultimate tensile strength and elongation of the HECAPed samples improved by~208%,~144%and~100%compared to the homogenized one,respectively.Crystallographic texture analysis indicated that most of the grains at the surface were reoriented parallel to the(0001)basal plane after HECAP process.Electrochemical corrosion tests and immersion results indicated that the sample with two passes of HEACP had the highest biocorrosion resistance confirming that the basal planes had the lowest corrosion rate compared to the non-basal ones.The mechanical behavior and bio-corrosion evaluation demonstrated that the HECAPed mg–Zn–Ca–mn alloy has great potential for biomedical applications and a mechanism was proposed to explain the interrelations between the thermomechanical processing and bio-corrosion behavior.

关键词： mg–Zn–Ca–mn alloy HECAP process microstructure mechanical properties Bio-corrosion performance

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role of quantum paths in generation of attosecond pulses

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Chinese Physics B 2020年第10期29卷 276-281页

作者： m r Sami A Shahbaz Department of Physics Government College UniversityP.O.Box 54000 LahorePakistan

We investigate the role of core potential in high ionization potential systems on high harmonic generation (HHG) spectra and obtain attosecond pulses. In our scheme, we use a standard soft core potential to model high ionization potential systems and irradiated these systems with fixed laser parameters. We observe the role of these systems on all the three steps involved in HHG process including ionization, propagation and recombination. In our study, the results illustrate that for high ionization potential systems, the HHG process is more sensitive to the ionization probability compared to the recombination amplitude. We also observe that due to the stronger core potential, small oscillations of the electrons during the propagation do not contribute to the HHG spectrum, which implies the dominance of only long quantum paths in the HHG spectrum. Our results, for attosecond pulse generation, show that long quantum path electrons are responsible for the supercontinuum region near the cutoff, which is suitable for the extraction of a single attosecond pulse in this region.

关键词： high-order harmonic generation attosecond pulses quantum paths strong nuclear potential

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Oblique collisional effects of dust acoustic waves in unmagnetized dusty plasma

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Chinese Physics B 2020年第6期29卷 304-313页

作者： m S Alam m r Talukder Department of mathematics Chittagong University of Engineering and TechnologyChittagong-4349Bangladesh Plasma Science and Technology Laboratory Department of Electrical and Electronic EngineeringUniversity of RajshahiRajshahi-6205Bangladesh

Effects of oblique collisions of the dust acoustic(DA)waves in dusty plasma are studied by considering unmagnetized fully ionized plasma.The plasma consists of inertial warm negatively charged massive dusts,positively charged dusts,superthermal kappa distributed electrons,and isothermal ions.The extended Poincaré–Lighthill–Kuo(e PLK)method is employed for the drivation of two-sided Korteweg–de Vries(KdV)equations(KdVEs).The Kd V soliton solutions are derived by using the hyperbolic secant method.The effects of superthermality index of electrons,temperature ratio of isothermal ion to electron,and the density ratio of isothermal ions to negatively charged massive dusts on nonlinear coefficients are investigated.The effects of oblique collision on amplitude,phase shift,and potential profile of right traveling solitons of DA waves are also studied.The study reveals that the new nonlinear wave structures are produced in the colliding region due to head-on collision of the two counter propagating DA waves.The nonlinearity is found to decrease with the increasing density ratio of ion to negative dust in the critical region.The phase shifts decrease(increase)with increasing the temperature ratio of ion to electron(κe).The hump(compressive,κerarefactive,κe>κec)solitons are produced depending on the angle(θ)of oblique collision between the two waves.

关键词： ion acoustic wave dusty plasma kappa distribution ePLK method hyperbolic secant method

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