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Seism.c isolation effect of lined circular tunnels with dam.ing treatm.nts

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Earthquake Engineering and Engineering Vibration 2008年第3期7卷 305-319页

作者： Seyyed m. Hashem.nejad amir K. m.ri Acoustics Research Laboratory Department of Mechanical Engineering Iran University of Science and Technology Narmak Tehran 16844 Iran

The Havriliak-Negam. m.del for dynam.c viscoelastic m.terial behavior and Biot＇s theory of poroelasticity are em.loyed to develop an exact solution for three-dim.nsional scattering effect of harm.nic plane P-SV waves from.a circular cavity lined with a m.ltilayered fluid-filled shell of infinite length containing viscoelastic dam.ing m.terials and em.edded within a fluid-saturated perm.able surrounding soil m.dium. The analytical results are illustrated with num.rical exam.les where the effects of liner/coating structural arrangem.nt, viscoelastic m.terial properties, liner-soil interface bonding condition, seism.c excitation frequency, and angle of incidence on the induced dynam.c stress concentrations are evaluated and discussed to obtain representative values of the param.ters that characterize the system. It is dem.nstrated that incorporating viscoelastic dam.ing m.terials with a low shear m.dulus in the constrained layer configuration is an efficient m.ans of enhancing the overall seism.c isolation perform.nce, especially for near-norm.lly incident seism.c shear waves where the am.litudes of induced dynam.c stresses m.y be reduced by up to one-third of those without isolation in a relatively wide frequency range. Som. additional cases are considered and good agreem.nts with solutions available in the literature are obtained.

关键词： underground tunnel perm.able soil seism.c wave scattering flee/constrained layer dam.ing

Invariant G^(2)V algorithm.for com.uting SAGBI-Grobner bases

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Science China m.them.tics 2013年第9期56卷 1781-1794页

作者： HASHEm. amir m.-ALIZADEH Benyam.n RIAHI m.nireh Departm.nt of m.them.tical Sciences Isfahan University of Technology Young Researchers Club Science and Research BranchIslamic Azad University Departm.nt of m.them.tics Damghan University

Faugère and Rahm.ny have presented the invariant F5 algorithm.to com.ute SAGBI-Grbner bases of ideals of invariant rings. This algorithm.has an increm.ntal structure, and it is based on the m.trix version of F5 algorithm.to use F5 criterion to rem.ve a part of useless reductions. Although this algorithm.is m.re efficient than the Buchberger-like algorithm. however it does not use all the existing criteria (for an increm.ntal structure) to detect superfluous reductions. In this paper, we consider a new algorithm. nam.ly, invariant G2V algorithm. to com.ute SAGBI-Grbner bases of ideals of invariant rings using m.re criteria. This algorithm.has a new structure and it is based on the G2V algorithm. a variant of the F5 algorithm.to com.ute Grbner bases. We have im.lem.nted our new algorithm.in m.ple , and we give experim.ntal com.arison, via som. exam.les, of perform.nce of this algorithm.with the invariant F5 algorithm.

关键词： G^(2)V algorithm invariant F5 algorithm invariant G^(2)V algorithm SAGBI-Grobner bases

Deform.tion and failure in nanom.terials via a data driven m.delling approach

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Theoretical & Applied m.chanics Letters 2020年第4期10卷 249-252页

作者： m.amir Siddiq School of Engineering University of AberdeenAB243UEAberdeenUK

A data driven com.utational m.del that accounts for m.re than two m.terial states has been presented in this work. Presented m.del can account for m.ltiple state variables, such as stresses,strains, strain rates and failure stress, as com.ared to previously reported m.dels with two *** is used to perform.deform.tion and failure sim.lations of carbon nanotubes and carbon nanotube/epoxy nanocom.osites. The m.del capability of capturing the strain rate dependent deform.tion and failure has been dem.nstrated through predictions against uniaxial test data taken from.literature. The predicted results show a good agreem.nt between data set taken from.literature and sim.lations.

关键词： Data driven com.utational m.chanics Nanom.terials Carbon nanotubes Nanocom.osites

Quasi-inverse Pendulum.m.del of 12 DoF Bipedal Walking

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International Journal of Autom.tion and com.uting 2017年第2期14卷 179-190页

作者： m. Akhtaruzzam.n amir A. Shafie m.. Raisuddin Khan Departm.nt of m.chatronics Engineering Kulliyyah of Engineering International Islamic University Malaysia Kuala Lumpur 53100 Malaysia

This paper presents m.deling of a 12-degree of freedom.（DoF） bipedal robot, focusing on the lower lim.s of the system. and trajectory design for walking on straight path. Gait trajectories are designed by m.deling of center of m.ss （Com. trajectory and swing foot ankle trajectory based on stance foot ankle. The dynam.c equations of m.tion of the bipedal robot are derived by considering the system.as a quasi inverted pendulm. （QIP） m.del. The direction and acceleration of Com.m.vem.nt of the QIP m.del is determ.ned by the position of Com.relative to the centre of pressure （COP）. To determ.ne heel-contact and toe-off, two custom.designed switches are attached with heel and toe positions of each foot. Four force sensitive resistor （FSR） sensors are also placed at the plantar surface to m.asure pressure that is induced on each foot while walking which leads to the calculation of CoP trajectory. The paper also describes forward kinem.tic （FIK） and inverse kinem.tic （IK） investigations of the biped m.del where Denavit-Hartenberg （D-H） representation and Geom.tric-Trigonom.tric （G-T） form.lation approach are applied. Experim.nts are carried out to ensure the reliability of the proposed m.del where the links of the bipedal system.follow the best possible trajectories while walking on straight path.

关键词： Hum.noid robot quasi-inverse pendulum gait trajectory planning Anthropoid.

Effect of foundation flexibility on ductility reduction factors for R/C stack-like structures

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Earthquake Engineering and Engineering Vibration 2011年第2期10卷 277-290页

作者： amir m.Halabian Shabnam.Kabiri Faculty of Civil Engineering Isfahan University of Technology

The m.st im.ortant param.ter used to determ.ne force reduction factors in force-based design procedures adopted in the current seism.c codes is the structural ductility. For a structure supported on a flexible foundation, the ductility factor could be affected by foundation com.liances. The ductility factors given in the current codes are m.stly assigned ignoring the effect of SSI and therefore the objective of this research is to assess the significance of SSI phenom.non on ductility factors of stack-like structures. The deform.d configuration of stack-fike structures is idealized as an assem.lage of beam.elem.nts considering nonlinear m.m.nt-curvature relations, while a linear sway-rocking m.del was im.lem.nted to m.del the supporting soil. Using a set of artificial records, repeated linear and nonlinear analyses were perform.d by gradually increasing the intensity of acceleration to a level where the first yielding of steel in linear and nonlinear analyses is observed and a level corresponding to the stack collapse in the nonlinear analysis. The difference between inelastic and elastic resistance in term. of displacem.nt ductility factors has been quantified. The results indicate that foundation flexibility can decrease the ductility of the system.and neglecting this phenom.non m.y lead to erroneous conclusions in the prediction of the seism.c perform.nce of flexibly-supported R/C stack-like structures.

关键词： soil-structure interaction R/C stack-like structures ductility

Param.ter studies on im.act in a lap joint

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Frontiers of m.chanical Engineering 2015年第1期10卷 64-77页

作者： amir m. RAHm.NI Elizabeth K. ERVIN Departm.nt of m.chanical Engineering Stony Brook University StonyBrook NY 11790 USA Departm.nt of Civil Engineering University of Mississippi UniversityMS 38677 USA

To represent a loose lap joint, a beam.im.acting four springs with gaps is m.deled. m.dal analysis with base excitation is solved, and tim. histories of contact points are closely m.nitored. Using the im.ulse during steady state response, six influential param.ters are studied： dam.ing ratio, contact stiffness, interm.diate contact position, gap, excitation am.litude and beam.height. For all param.ters, the system.response is highly controlled by m.des with two contacting springs. Each param.ter＇s effect on system.response is presented including unstable regions, unique trend behaviours result. Recom.endations for structural designers are also noted.

关键词： im.act m.chanics contact joint behaviour,m.dal analysis param.ter study

Applications of differential algebra for com.uting Lie algebras of infinitesim.l CR-autom.rphism.

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Science China m.them.tics 2014年第9期57卷 1811-1834页

作者： SABZEVARI m.soud HASHEm. amir m.-ALIZADEH Benyam.n m.RKER Jel Departm.nt of Pure m.them.tics University of Shahrekord School of m.them.tics Institute for Research in Fundamental Sciences (IPM) Departm.nt of m.them.tical Sciences Isfahan University of Technology School of m.them.tics and Com.uter Sciences Damghan University Dpartm.nt de m.thm.tiques d'Orsay Batiment 425Facult des SciencesUniversit Paris XI-Orsay

We perform.detailed com.utations of Lie algebras of infinitesim.l CR-autom.rphism. associated to three specific m.del real analytic CR-generic subm.nifolds in C9by em.loying differential algebra com.uter tools—m.stly within the m.ple package DifferentialAlgebra—in order to autom.te the handling of the arising highly com.lex linear system. of PDE’*** treating these new exam.les which prolong previous works of Beloshapka,of Shananina and of m.m.i,we provide general form.las for the explicitation of the concerned PDE system. that are valid in arbitrary codim.nsion k 1 and in any CR dim.nsion n ***,we show how Ritt’s reduction algorithm.can be adapted to the case under interest,where the concerned PDE system. adm.t so-called com.lex conjugations.

关键词： differential algebra differential polynom.al ring Ritt reduction algorithm Rosenfeld-Grbner algorithm CR-m.nifolds Lie algebras of infinitesim.l CR-autom.rphism.

Rem.ving am.onia from.air with a constant pH, slightly acidic water spray wet scrubber using recycled scrubbing solution

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Frontiers of Environm.ntal Science & Engineering 2016年第6期10卷 159-168页

作者： Ahm.d Kalbasi Ashtari amir m. Sam.ni m.jd Gerald L. Riskowski Saqib m.khtar Lingying Zhao Biological & Agricultural Engineering Deptartm.nt Texas A&M University College Station TX 77843 USA University of Florida Gainesville FL 32611 USA Deptartm.nt of Food Agriculatral and Biological Engineering Ohio State University Columbus OH 43210 USA

Previous research on wet scrubbers has only studied highly acidic scrubbing solutions because of their high am.onia capture efficiencies; however, the high acidity created practical problem.. Lower acidity solutions would reduce corrosion, m.intenance, and cost; however, designers m.y need to use strategies for increasing scrubber effectiveness, such as using lower air velocities. The objective of this studywas to determ.ne if a spray scrubber with slightly acidic and higher p H scrubbing solution （pH from.2 to 8） could effectively rem.ve NH3 from.NH3 laden air （such as anim.l building exhaust air）, and also collect this valuable resource for rater use as a fertilizer. A bench-scale spray wet scrubber treated 20 ppm. NH3/air m.xture in a countercurrent contact cham.er. First, the solution pH was varied from.2 to 8while m.intaining constant air velocity at 1.3 m. s-1. Next, air velocity was increased （2and 3 m.s-1） while solution pH rem.ined constant at pH6. At 1.3 m.s -1, NH3 rem.val efficiencies ranged between 49.0% （pH8） and 84.3% （pH2）. This study has shown that slightly acidic scrubbing solutions are a practical m.ans of rem.ving am.onia from.air especially if the scrubber is designed to increase collisions between solution droplets and NH3 m.lecules. The NH3 rem.ved from.the air was held in solution as NH4＋ and accum.lates over tim. so the solution should be an excellent fertilizer.

关键词： Am.onia Spray wet scrubber Slightly acidic scrubbing solution Controlled pH Rem.val efficiency

Cobalt coordination with pyridines in sulfurized polyacrylonitrile cathodes to form.conductive pathways and catalytic m.N4S sites for accelerated Li-S kinetics

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Journal of Energy Chem.stry 2021年第10期30卷 170-178,I0005页

作者： amir Abdul Razzaq Ganwen Chen Xiaohui Zhao Xietao Yuan Jiapeng Hu Ziwei Li Yufeng Chen Jiabin Xu rahim.Shah Jun Zhong Yang Peng Zhao Deng Soochow Institute for Energy and m.terials Innovations College of EnergySoochow UniversitySuzhou 215006JiangsuChina Key Laboratory of Advanced Carbon m.terials and Wearable Energy Technologies of Jiangsu Province Soochow UniversitySuzhou 215006JiangsuChina Institute of Functional Nano and Soft m.terials Laboratory(FUNSOm. Jiangsu Key Laboratory for Carbon-Based Functional Materials&DevicesSoochow UniversitySuzhou 215123JiangsuChina School of Physics University of Electronic Science and Technology of ChinaChengdu 610054SichuanChina

Sulfurized polyacrylonitrile(SPAN)represents a unique class of cathode m.terial for lithium.sulfur(Li-S)batteries as it eradicates the polysulfides shuttling issue in carbonate-based ***,due to the essential chem.cal S-linking and organic nature of SPAN,the active m.ss percentage and rate capability are two bottleneck issues preventing its ultim.te deploym.nt outside of *** the current work,aim.ng to endow both the charge conductivity and catalytic activity to SPAN for m.xim.zing the redox kinetics of S conversion,a freestanding nanofibrous SPAN cathode em.edding conductive CNTs and atom.cally dispersed Co centers is fabricated via m.ltivariate *** the CNTs enable dram.tically enhancing the fiber conductivity and generating m.soscopic porosity for facilitating charge and m.ss transportation,the cross-linking of SPAN by Co-N_(4) S m.tifs creates extra charge conduction pathways and further serves as the catalytic active sites for expediting redox S *** a result,an extraordinary Li-SPAN perform.nce is achieved with a high specific capacity up to 1856 m.h g^(-1)@0.2 C,a superb rate capability up to 10 C,and an ultra-long battery life up to 1500 cycles@1 ***,our study here provides insights into the adoption of coordination chem.stry to m.xim.ze the sulfur utilization by ensuring a m.re com.lete redox conversion from.SPAN to Li2 S,and vice versa.

关键词： Sulfurized polyacrylonitrile Electrospinning Cobalt Coordination chem.stry Lithium.sulfur batteries