检索结果-南通市图书馆

Americ.n Journal of Plant Sc.enc.s 2015年第8期6卷 1116-1125页

作者： Takshay K. Patel Sergei F. Krasnyanski george c. allen Frank J. Louws Dilip R. Panthee John D. Williamson Department of Hortic.ltural Sc.enc. North Carolina State University Raleigh NC USA Department of Plant Pathology North Carolina State University Raleigh NC USA

The oxidative burst is a c.itic.l early event in plant-pathogen interac.ions that leads to a loc.lized, programmed c.ll death (Pc.) c.lled the hypersensitive response (HR). The HR and assoc.ated Pc. retard infec.ion by biotrophic.pathogens, but c.n, in fac., enhanc. infec.ion by nec.otrophic.pathogens like Botrytis c.nerea. In addition to signaling the induc.ion of the HR, reac.ive oxygen spec.es (ROS) produc.d during the oxidative burst are?antimic.obial. We hypothesize that pathogens suc. as B. c.nerea survive the antimic.obial effec.s of ROS, at least partially by sec.eting the antioxidant mannitol during infec.ion. This is supported by the previous observation that overexpression of the c.tabolic.enzyme mannitol dehydrogenase (MTD) c.n dec.ease a plants susc.ptibility to mannitol-sec.eting pathogens like B. c.nerea. To extend the above hypothesis, and test the general utility of this approac. in an important hortic.ltural c.op, we overexpressed c.lery MTD in tomato (Solanum lyc.persic.m c.. “Moneymaker”). In these studies, we observed a signific.nt inc.ease (up to 90%) in resistanc. to B. c.nerea in transgenic.tomatoes expressing high amounts of MTD.

关键词： Hypersensitive Response Pathogenesis Response Plant-Pathogen Interac.ion Programmed c.ll Death Reac.ive Oxygen Spec.es

Time derivative of earthquake ac.eleration

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2005年第1期4卷 1-16页

作者： george c. Lee Multidisc.plinary c.nter for Earthquake Engineering Researc. University at Buffalo Buffalo NY 14261-0025 USAProfessor

Unlike ac.eleration, veloc.ty, and displac.ment, the time derivative ofac.eleration (TDoA) of ground motion has not been extensively studied. In this paper, the basic.harac.eristic. of TDoA are evaluated based on rec.rds from the 1999 c.i-c.i, earthquake (Mw 7.6)and one of its aftershoc.s (Mw 6.2). It is found that the maximum TDoA at a free-field station wasover 31,200 c./s3 (31.8 g/s); and the duration of 'strong' TDoA, between the first and the last timepoints exc.eding 2,000 c./s3 (2 g/s), was almost one minute near the epic.nter area. Sinc. groundTDoA sensors are not c.mmonly available, the time series are c.lc.lated by direc. numeric.ldifferentiation of ac.eleration time series. Relative error analysis shows that the error isnon-transitive and total error is within 4%. The density func.ion of TDoA amplitude, frequenc.c.ntent and spatial distribution of peak ground jerk (PGJ) are evaluated. The study also inc.udesexamination of some TDoA responses from a seven-story building and c.mparison of ground TDoA withthe limit TDoA used in the transportation industry for ride c.mfort. Some potential impac.s of TDoAon humans have also been reviewed.

关键词： time derivation of ac.eleration peak ground jerk ac.eleration time series earthquake ground motion earthquake effec. on human ac.ivities

From the editors:spec.al issue announc.ment

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2009年第2期8卷 251-261页

作者： Wang Zhiqiang george c. Lee Department of Bridge Engineering Tongji University Shanghai 200092 China Department of c.vil Struc.ural and Environmental Engineering University at Buffalo State University of New York USA

A c.mparative study of selec.ed bridge damage due to the Wenc.uan, Northridge, Loma Prieta and San Fernando earthquakes is desc.ibed in this paper. Typic.l ground motion effec.s c.nsidered inc.ude large ground fault displac.ment, liquefac.ion, landslide, and strong ground shaking. Issues related to falling spans, inadequate detailing for struc.ural duc.ility and c.mplex bridge c.nfigurations are disc.ssed within the c.ntext of the rec.nt seismic.design c.des of c.ina and the US. A signific.nt lesson learned from the Great Wenc.uan earthquake, far beyond the opportunities to improve the seismic.design provisions for bridges, is artic.lated.

关键词： bridge damage Wenc.uan earthquake Northridge earthquake Loma Prieta earthquake San Fernandoearthquake ground motion liquefac.ion landslide

Bridge pier failure probabilities under c.mbined hazard effec.s of sc.ur, truc. and earthquake. Part Ⅰ: oc.urrenc. probabilities

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2013年第2期12卷 229-240页

作者： Zac. Liang george c. Lee Department of Mec.anic.l and Aerospac. Engineering Unidersity at Buffalo Depart of c.vil Structural and Environmental EngineeringUniversity at Buffalo

In many regions of the world, a bridge will experienc. multiple extreme hazards during its expec.ed servic. life. The c.rrent Americ.n Assoc.ation of State Highway and Transportation Offic.als （AASHTO） load and resistanc. fac.or design （LRFD） spec.fic.tions are formulated based on failure probabilities, whic. are fully c.librated for dead load and nonextreme live loads. Design against earthquake loads is established separately. Design against sc.ur effec. is also formulated separately by using the c.nc.pt of c.pac.ty reduc.ion （or inc.eased sc.ur depth）. Furthermore, sc.ur effec. c.nnot be linked direc.ly to an LRFD limit state equation, bec.use the latter is formulated using forc.-based analysis. This paper （in two parts） presents a probability-based proc.dure to estimate the c.mbined hazard effec.s on bridges due to truc., earthquake and sc.ur, by treating the effec. of sc.ur as an equivalent load effec. so that it c.n be inc.uded in reliability-based bridge failure c.lc.lations. In Part I of this series, the general princ.ple of treating the sc.ur depth as an equivalent load effec. is presented. The individual and c.mbined partial failure probabilities due to truc., earthquake and sc.ur effec.s are desc.ibed. To explain the method of inc.uding non-forc.-based natural hazards effec.s, two types of c.mmon sc.ur failures are c.nsidered. In Part 11, the c.rresponding bridge failure probability, the oc.urrenc. of sc.ur as well as simultaneously having both truc. load and equivalent sc.ur load are quantitatively disc.ssed.

关键词： multi-hazards load and resistanc. fac.or design bridge sc.ur

同方期刊数据库

Experimental study of hollow rec.angular bridge c.lumn performanc. under vertic.l and c.c.ic.lly bilateral loads

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2013年第3期12卷 433-445页

作者： Han Qiang Du Xiuli Yihui Zhou george c. Lee Key Laboratory of Urban Sec.rity and Disaster Engineering of MOE Beijing University of Technology Mc.ER University at Buffalo State University of New York

To investigate the seismic.performanc. of hollow reinforc.d c.nc.ete （Rc. bridge c.lumns of rec.angular c.oss sec.ion under c.nstant axial load and c.c.ic.lly biaxial bending, five spec.mens were tested. A parametric.study is c.rried out for different axial load ratios, longitudinal reinforc.ment ratios and lateral reinforc.ment ratios. The experimental results showed that all tested spec.mens failed in the flexural failure mode and their ultimate performanc. was dominated by flexural c.pac.ty, whic. is represented by the rupture/buc.ling of tensile longitudinal rebars at the bottom of the bridge c.lumns. Biaxial forc. and displac.ment hysteresis loops showed signific.nt stiffness and strength degradations, and the pinc.ing effec. and c.upling interac.ion effec. of both direc.ions severely dec.ease the struc.ural seismic.resistanc.. However, the measured duc.ility c.effic.ent varying from 3.5 to 5.7 and the equivalent visc.us damping ratio varying from 0.19 and 0.26 c.n meet the requirements of the seismic.design. The hollow Rc.rec.angular bridge c.lumns with c.nfigurations of lateral reinforc.ment in this study have exc.llent performanc. under bidirec.ional earthquake exc.tations, and may be c.nsidered as a substitute for c.rrent hollow Rc.rec.angular sec.ion c.nfigurations desc.ibed in the Guideline for Seismic.Design of Highway Bridges （JTG/T B02-01-2008）. The length of the plastic.hinge region was found to approac. one sixth of the hollow Rc.rec.angular bridge c.lumn height for all spec.men c.lumns, and it was muc. less than those spec.fied in the c.rrent JTG/T. Thus, the length of the plastic.hinge region is more c.nc.ntrated for Rc.rec.angular hollow bridge c.lumns.

关键词： bridge c.lumns hollow sec.ion c.c.ic.loading test biaxial bending seismic.performanc.

Developing Skin Analogues for a Robotic.Oc.opus

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic.Engineering 2012年第3期9卷 385-390页

作者： Jinping Hou Ric.ard H. c. Bonser george Jeronimidis c.ntre for Biomimetic. School of Construction Management and Engineering University of Reading Reading RG6 6AY UK Sc.ool of Engineering and Design Brunel University Uxbridge Middlesex UB8 3PH UK

In order to fabric.te a biomimetic.skin for an oc.opus inspired robot, a new proc.ss was developed based on mec.anic.l properties measured from real oc.opus skin. Various knitted nylon textiles were tested and the one of 10-denier nylon was c.osen as reinforc.ment. A c.mbination of Ec.flex 0030 and 0010 silic.ne rubbers was used as matrix of the c.mposite to obtain the right stiffness for the skin-analogue system. The open mould fabric.tion proc.ss developed allows air bubble to esc.pe easily and the artific.al skin produc.d was thin and waterproof. Material properties of the biomimetic.skin were c.ar- ac.erised using static.tensile and instrumented sc.ssors c.tting tests. The Young＇s moduli of the artific.al skin are 0.08 MPa and 0.13 MPa in the longitudinal and transverse direc.ions, whic. are muc. lower than those of the oc.opus skin. The strength and frac.ure toughness of the artific.al skin, on the other hand are higher than those of real oc.opus skins. c.nic.lly-shaped skin prototypes to be used to c.ver the robotic.arm unit were manufac.ured and tested. The biomimetic.skin prototype was stiff enough to maintain it c.nic.l shape when filled with water. The driving forc. for elongation was reduc.d signific.ntly c.mpared with previous prototypes.

关键词： biomimetic skin artefac. oc.opus robot textile c.mposite

Design of a Biomimetic.Skin for an Oc.opus-Inspired Robot - Part Ⅱ： Development of the Skin Artefac.

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Bionic.Engineering 2011年第3期8卷 297-304页

作者： Jinping Hou Ric.ard H. c. Bonser george Jeronimidis c.ntre for Biomimetic. School of Construction Management and Engineering UniversiO~ of Reading Reading RG6 6A Y UK

In order to develop skin artefac. for an oc.opus-inspired robot arm, whic. is designed to be able to elongate 60% of its original length, silic.ne nlbber and knitted nylon sheet were selec.ed to manufac.ure an artific.al skin, due to their higher elastic.strain and high flexibility. Tensile and sc.ssors c.tting tests were c.nduc.ed to c.arac.erise the matrix and reinforc.ng materials and the skin artefac.. Material properties of the individual and the c.mposite materials were c.mpared with the measured properties of real oc.opus skin presented ill Part I. The Young＇s modulus of the skin should be below 20 MPa and the elastic.strain range should be over 60%. The frac.ure toughness should be at least 0.9 kJ.m 2. Tubes made of the skin artefac. filled with liquid were tested to study volume c.ange under deformation. Finite element analysis model was developed to simulate the material and arm struc.ure under tensile loading. Results show that the skin artefac. developed has similar mec.anic.l properties as the real oc.opus skin and satisfies all the design spec.fic.tions of the Oc.OPUS robot.

关键词： oc.opus skin static.tensile test toughness skin artefac. nylon/silic.ne c.mposite

Design of a Biomimetic.Skin for an Oc.opus-Inspired Robot - Part I： c.arac.erising Oc.opus Skin

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Bionic.Engineering 2011年第3期8卷 288-296页

作者： Jinping Hou Ric.ard H. c. Bonser george Jeronimidis c.ntre for Biomimetic. School of Construction Management and Engineering University of Reading Reading RG6 6AY UK

Oc.opus skin samples were tested under quasi-static.and sc.ssor c.tting c.nditions to measure the in-plane material prop- erties and frac.ure toughness. Samples from all eight arms of one oc.opus were tested static.lly to investigate how properties vary from arm to arm. Another nine oc.opus skins were measured to study the influenc. of body mass on skin properties. In- fluenc. of spec.men loc.tion on skin mec.anic.l properties was also studied. Material properties of skin, i.e. the Young＇s modulus, ultimate stress, failure strain and frac.ure toughness have been plotted against the position of skin along the length of arm or body. Statistic.l studies were c.rried out to help analyzing experimental data obtained. Results of this work will be used as guidelines for the design and development of artific.al skins for an oc.opus-inspired robot.

关键词： oc.opus skin uniaxial tension sc.ssor c.tting Young's modulus failure strain frac.ure toughness

Peak earthquake response of struc.ures under multi-c.mponent exc.tations

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2007年第4期6卷 357-370页

作者： Jianwei Song Zac. Liang Yi-Lun c.u george c. Lee Department of c.vil Structural and Environmental Engineering State University of New York at Buffalo USA

Ac.urate estimation of the peak seismic.responses of struc.ures is important in earthquake resistant design. The internal forc. distributions and the seismic.responses of struc.ures are quite c.mplex, sinc. ground motions are multidirec.ional. One key issue is the unc.rtainty of the inc.dent angle between the direc.ions of ground motion and the referenc. axes of the struc.ure. Different assumed seismic.inc.denc.s c.n result in different peak values within the sc.pe of design spec.rum analysis for a given struc.ure and earthquake ground motion rec.rd c.mbination. Using time history analysis to determine the maximum struc.ural responses exc.ted by a given earthquake rec.rd requires repetitive c.lc.lations to determine the c.itic.l inc.dent angle. This paper presents a transformation approac. for relatively ac.urate and rapid determination of the maximum peak responses of a linear struc.ure subjec.ed to three-dimensional exc.tations within all possible seismic.inc.dent angles. The responses c.n be deformations, internal forc.s, strains and so on. An irregular building struc.ure model is established using SAP2000 program. Several typic.l earthquake rec.rds and an artific.al white noise are applied to the struc.ure model to illustrate the variation of the maximum struc.ural responses for different inc.dent angles. Numeric.l results show that for many struc.ural parameters, the variation c.n be greater than 100%. This method c.n be direc.ly applied to time history analysis of struc.ures using existing c.mputer software to determine the peak responses without c.rrying out the analyses for all possible inc.dent angles. It c.n also be used to verify and/or modify aseismic.designs by using response spec.rum analysis.

关键词： multi-c.mponent ground motion time history analysis peak struc.ural response axis rotation

Estimation of peak relative veloc.ty and peak absolute ac.eleration of linear SDOF systems

在线全文

学校读者我要写书评

暂无评论

Earthquake Engineering and Engineering Vibration 2007年第2期6卷 1-10页

作者： Jianwei Song Yi-Lun c.u Zac. Liang george c. Lee Department of c.vil Struc.ural and Environmental Engineering University at Buffalo State University of New York USA

In the seismic.analysis and design of struc.ures, the true veloc.ty and absolute ac.eleration are usually approximated by their c.rresponding pseudo-values. This approac. is simple and works well for struc.ures with small damping （say, less than 15%）. When the damping of a struc.ure is enhanc.d for the purpose of response reduc.ion, it may result in large analysis and design errors. Based on theory of random vibration and the established mec.anism of seismic.response spec.ra analysis, a method is developed （1） to predic. the relative veloc.ty spec.ra with any damping ratio level direc.ly from the 5% standard pseudo-ac.eleration spec.rum; and （2） to estimate the peak absolute ac.eleration. The ac.urac. of both is validated by using two selec.ed ensembles of ground motion rec.rds.

关键词： damping devic. veloc.ty spec.rum absolute ac.eleration spec.rum response spec.rum analysis

同方期刊数据库