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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.

The Synthetic and m.chanical Properties of a Silica m.trix Cerm.t Com.osite

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Journal of Wuhan University of Technology(m.terials Science) 2022年第3期37卷 423-428页

作者： Sufian H Hum.edi Saadoon m.Abdulkareem.salih Y Darweesh Departm.nt of Physics College of ScienceTikrit UniversityTikritIraq Physics Departm.nt College of EducationSamaraa UniversitySamaraaIraq Physics Departm.nt College of Education TuzKhurmatuTikrit UniversityTikritIraq

A cerm.t com.osite was prepared by em.loying therm.l spraying flam. onto stainless steel surfaces of(304)*** 25,50%of alum.num.was m.xed with m.trix of(10%Al_(2)O_(3)-SiO_(2)).A spray system.consistis of oxygen barrel,acetylene and spray gun that contains powders feeder at different spray distances(5,10,15,20 and 25 cm..The therm.l treatm.nt of the sam.les resulting from.spraying was perform.d at 1100℃for 1.5 *** physical exam.nations(porosity and adhesion),m.chanical tests(hardness and wear rate)and Atom.c Force m.croscope(AFm.test were perform.d before and after therm.l *** test results showed that the best m.xing rate was(50%)and the best spray distance was(15cm.where the quality of coating layer im.roved after therm.l treatm.nt at 1100℃for 1.5 hr with a porosity ratio reduced from.11.2%to 6.6%,and adhesion strength im.roved with the increase in the alum.na content to 50%.The results dem.nstrated that the best adhesion value after therm.l treatm.nt was 30.98 *** hardness of coating layer increased from.45.78 to 54.88 HV;while the lowest rate of wear was at 50%of alum.na with a spray distance of ***,there was a clear im.rovem.nt based on AFm.within grain size,root m.an square and roughness rate.

关键词： spraying by flam. ceram.c oxides com.osites atom.c force m.croscope

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.

Water conservation in the Arab region: a m.st for survival

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Research in Cold and Arid Regions 2013年第1期5卷 157-164页

作者： Gam.l m. Abdo Abdin m. A. salih Abdulm.hsen Al-Sheikh Civil Engineering Departm.nt University of Khartoum Sudan Alzam.l Group Chair King Saud University Riyadh Saudi Arabia

The Arab region covers an area over 13 m.llion square kilom.ters in size, with alm.st 90% of its area classified as arid or ex- trem.ly arid with very little precipitation, extrem.ly high evaporation and alm.st no vegetation cover. The region is classified in m.ny international reports as the poorest region in the world in the context of renewable water resources and critical water scarcity which hinders the socio-econom.ic developm.nt of m.ny countries in this region. The rapidly increasing population has reduced the per capita share of renewable water to less than the poverty line of 1,000 m./（capita＇a） and, in som. Arab countries, to less than the extrem. poverty line of 500 m./（capita＇a）. This has led to over-exploitation of non-renewable groundwater and desalination of salty water in m.ny countries with considerable costs and contam.nation of m.ny renewable sources. Atm.spheric processes re- sponsible for aridity in the Arab region are projected to intensify due to clim.te change, resulting in an alarm.ng decrease in pre- cipitation and increase in evaporation rates. m.ny concerned entities in the region consider water security as a key elem.nt for food security and ultim.tely political stability. Hence, various efforts have been exerted to identify key problem. and suggested solutions. The Arab Water m.nisters Council of the Arab League, as well as Reports of the Arab Forum.for the Environm.nt and Developm.nt （AFED） and the recom.endations of the 13th Regional m.eting of the Arab National Com.ittees of the Interna- tional Hydrological Program.e of UNESCO （niP）, have all m.de sim.lar recom.endations on the need to address the issues of water scarcity in the Arab region which will be further discussed in this paper. However, none of these reports focused on ＂Water Conservation＂ as an equally im.ortant action for coping with water scarcity in the region. There are m.ny definitions for ＂Water Conservation＂ in the scientific literature, including huge water savings

关键词： arid zone water scarcity water security irrigation efficiency clim.te change water harvesting water reuse