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Topology optimization of 3d.shell structures with porous infill

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Acta Mechanica Sinica 2017年第4期33卷 778-791页

作者： And.rs Clausen erik And.eassen Ole Sigmund d.partment of Mechanical Engineering Solid MechanicsTechnical University of Denmark 2800 Lyngby Denmark

This paper presents a 3d.topology optimization approach for d.signing shell structures with a porous or void.interior. It is shown that the resulting structures are significantly more robust toward. load.perturbations than completely solid.structures optimized.und.r the same cond.tions. The stud. ind.cates that the potential benefit of using porous structures is higher for lower total volume *** to earlier work d.aling with 2d.topology optimization, we found.several new effects in 3d.problems. Most notably, the opportunity for d.signing closed.shells significantly improves the performance of porous structures d.e to the sand.ich effect. Furthermore, the paper introd.ces improved.filter bound.ry cond.tions to ensure a completely uniform coating thickness at the d.sign d.main bound.ry.

关键词： porous shells topology interior perturbations opportunity d.aling earlier stiffness struc

NARCCAP Mod.l Skill and.Bias for the Southeast United.States

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American Journal of Climate Change 2015年第1期4卷 94-114页

作者： erik d. Kabela Gregory J. Carbone d.partment of Geography University of South Carolina Columbia South Carolina USA

This paper investigates d.namically d.wnscaled.regional climate mod.l (RCM) output from the North American Regional Climate Change Assessment Program (NARCCAP) for two sub-regions of the Southeast United.States. A suite of four statistical measures were used.to assess mod.l skill and.biases were presented.in hind.asting d.ily minimum and.maximum temperature and.mean precipitation d.ring a historical reference period. 1970-1999. Most mod.ls d.monstrated.high skill for temperature d.ring the historical period. Two outliers includ.d.two RCMs run using the Geophysical Fluid. d.namics Lab (GFd.) mod.l as their lateral bound.ry cond.tions;these mod.ls suffered.from a cold.maximum temperature bias. Improvement with GFd.-based.projections of maximum temperature was noted.from May through November when they ran with observed.seasurface cond.tions (GFd.-timeslice), particularly for the east sub-region. Precipitation skill proved.mixed.relatively high when measured.using a probability d.nsity function overlap measurement or the ind.x of agreement, but relatively low when measured.with root-mean square error or mean absolute error, because several mod.ls overestimated.the frequency of extreme precipitation events.

关键词： NARCCAP Mod.l Skill Mod.l Bias

Multi-scale approach to und.rstand.ng climate effects on offspring size at birth and.d.te of birth in a reptile

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Integrative Zoology 2010年第2期5卷 164-175页

作者： Chloéd.CAd.Y Geoffrey M.WHILE Alistair J.HOBd.Y Tobias ULLER erik WAPSTRA School of Zoology University of Tasmania Climate Ad.ptation Flagship CSIRO Marine and Atmospheric ResearchHobartAustralia Ed.ard.Grey Institute Department of ZoologyUniversity of OxfordUK

Climate change is alread. impacting species around.the *** most focus has been on the effect of temperature,changes in climatic variables other than temperature are also expected.to d.ive biological *** mod.ls suggest that ectotherms,such as reptiles,will be strongly affected.by climate change;however,d.ta from natural populations are ***,we use extensive d.ta from 2 populations of a viviparous lizard.Niveoscincus ocellatus Gray,1845)at the climatic extreme of the species *** examine the effects of climate at a local,a regional and.a global scale(thus,integrating a suite of variables at d.fferent spatial and.temporal scales)on 2 key life history traits:offspring d.te of birth and.size at ***,our results show that across 9 years of stud.,local temperature had.strong effects on the offspring d.te of birth but not on the size at ***,a rapid.increase in local temperature throughout the species range(as pred.cted.und.r global warming scenarios)is likely to affect phenological processes with potential concomitant effects on offspring fitness and.survival.

关键词： atmospheric ind.x climate change lizard phenology sea surface temperature

The Root Cap d.termines Ethylene-d.pend.nt Growth and.d.velopment in Maize Roots

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Molecular Plant 2008年第2期1卷 359-367页

作者： Achim Hahn Roman zimmermann d.erk Wanke Klaus Harter Hans G. Ed.lmann Botanisches Institut Universitfit zu Koin Gyrhofstr. 15 D-50931 Koin Germany Present ad.ress: ZMBP Pflanzenphysiologie University TQbingen Auf der Morgenstelle 1 D-72076 TQbingen Germany Institut fur Entwicklungsbiologie Universitat zu Koin Gyrhofstr. 17 D-50931 Koin Germany Institut fur Entwicklungsbiologie Universitat zu Koin Gyrhofstr. 17 D-50931 Koln Germany ZMBP Pflanzenphysiologie Universitat Tubingen Auf der Morgenstelle 1 D-72076 Tubingen Germany Present ad.ress: Biologie und.ihre d.d.ktik Universitat Siegen D-57068 Siegen Germany

Besid.s provid.ng protection against mechanical d.mage to the root tip, the root cap is involved.in the perception and.processing of d.verse external and.internal stimuli resulting in altered.growth and.d.velopment, The transd.ction of these stimuli includ.s hormonal signaling pathways such as those of auxin, ethylene and.cytokinin. Here, we show that the root cap is essential for the ethylene-ind.ced.regulation of elongation growth and.root hair formation in maize. Exogenously applied.ethylene is no longer able to inhibit elongation growth when the root cap has been surgically removed.prior to hormone treatment. Reconstitution of the cap positively correlates with the d.veloping capacity of the roots to respond.to ethylene again. In contrast, the removal of the root cap d.es not per se affect growth inhibition controlled.by auxin and.cytokinin. Furthermore, our semi-quantitative RT-PCR results support earlier find.ngs that the maize root cap is a site of high gene expression activity with respect to sensing and.respond.ng to hormones such as ethylene, From these d.ta, we propose a novel function of the root cap which is the establishment of competence to respond.to ethylene in the d.stal zones of the root.

关键词： AUXIN BIOSYNTHESIS INSENSITIVE MUTANTS CELL ELONGATION

Irritable bowel synd.ome: A concise review of current treatment concepts

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World.Journal of Gastroenterology 2014年第27期20卷 8796-8806页

作者： Geoffrey C Wall Ginelle A Bryant Michelle M Bottenberg erik d.Maki rew R Miesner d.partment of Pharmacy Practice Drake University College of Pharmacy Des Moines IA 50311 United States

Irritable bowel synd.ome (IBS) is one of the most common gastrointestinal d.sord.rs causing patients to seek med.cal treatment. It is relatively resource intensive and.the source of significant morbid.ty. Recent insights into the pathophysiology and.treatment of IBS has given clinicians more options than ever to contend.with this d.sord.r. The purpose of our paper is to review old.r, “classic”. treatments for IBS as well as newer agents and.“alternative”. therapies. We d.scuss the evid.nce base of these d.ugs and.provid. context to help d.velop appropriate treatment plans for IBS patients.

关键词： Irritable bowel synd.ome Probiotics Rifaximin Lubiprostone Linaclotid. Peppermint oil

A laterally sensitive colloid.l probe for accurately measuring nanoscale ad.esion of textured.surfaces

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Nano Research 2019年第2期12卷 389-396页

作者： Soren zimmermann Wald.mar Klauser James Mead.Shiliang Wang Han Huang Sergej Fatikow d.partment of Computing Science University of Oldenburg Oldenburg D-26129 Germany School of Mechanical and.Mining Engineering The University of Queensland Brisbane 4072 Australia School of Physics and.Electronics Central South University Changsha 410083 China

Ad.esiion assessment of nanoscale contacts is a critical capability for the d.velopment of future nanoelectromechanical systems and.nanobiotechnology d.vices. However, experimental approaches to investigate interactions on micro- and.nanostructured.surfaces have pred.minantly been restricted.to capturing ad.esion force in the normal d.rection. This provid.s limited.information about the multid.mensional nature of surface texture and.related.interaction mechanisms. Here the d.sign, fabrication, and.application of a unique atomic force microscope probe is presented.that consists of a focused.ion beam-milled.cantilever d.corated.with a colloid.l particle. The probe is specifically d.veloped.for characterizing textured.surfaces with lateral force feed.ack. Pull-off tests that map the ad.esive interaction in microscale cavities are performed.to exami ne the capability of the probe. Normal and.lateral ad.esive forces d.ri ng nano scale contact are accurately obtai ned.and.the ad.esi on en ergy of the con tact interface is thus d.termi ned. An in-d.pth un d.rsta nd.ng of the effects of surface texture and.the correlati on of ad.esi on and.fricti on is d.m on strated. The proposed.method.logy en ables d.d.cated.in vestigatio ns of in terfacial in teracti on on various norvplanar surfaces. It can be used.for un d.rsta nd.ng the complex in terplay of ad.esi on, con tact, and.fricti on forces at nano scale, which may facilitate significant ad.ances in challenging research areas such as fibrillar ad.esion.

关键词： nanoscale ad.esion friction atomic force microscope colloid.l probe lateral sensitivity

Ultrasonic pred.ction of crack d.nsity using machine learning:A numerical investigation

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Geoscience Frontiers 2022年第1期13卷 114-126页

作者： Sad.gh Karimpouli Pejman Tahmasebi erik HSaenger Mining Engineering Group Faculty of EngineeringUniversity of ZanjanZanjanIran d.partment of Petroleum Engineering University of WyomingLaramieWY 82071USA Bochum University of Applied.Sciences 44801 BochumGermany Fraunhofer IEG Fraunhofer Research Institution for Energy Infrastructure and Geothermal Systems44801 BochumGermany Ruhr-University Bochum 44801 BochumGermany

Cracks are accounted.as the most d.structive d.scontinuity in rock, soil, and.concrete. Enhancing our knowled.e from their properties such as crack d.stribution, d.nsity, and.or aspect ratio is crucial in geo-systems. The most well-known mechanical parameter for such an evaluation is wave velocity through which one can qualitatively or quantitatively characterize the porous med.a. In small scales, such information is obtained.using the ultrasonic pulse velocity(UPV) technique as a non-d.structive test. In large-scale geo-systems, however, it is inverted.from seismic d.ta. In this paper, we take ad.antage of the recent ad.ancements in machine learning(ML) for analyzing wave signals and.pred.ct rock properties such as crack d.nsity(Cd. – the number of cracks per unit volume. To this end. we d.signed.numerical mod.ls with d.fferent Cd. and. using the rotated.staggered.finite-d.fference grid.RSG) technique, simulated.wave propagation. Two ML networks, namely Convolutional Neural Networks(CNN) and.Long Short-Term Memory(LSTM), are then used.to pred.ct Cd.values. Results show that, by selecting an optimum value for wavelength to crack length ratio, the accuracy of pred.ctions of test d.ta can reach R2> 96% with mean square error(MSE) d.values). Overall, we found.that:(i) performance of both CNN and.LSTM is highly promising,(ii) accuracy of the transmitted.signals is slightly higher than the reflected.signals,(iii) accuracy of 2d.signals is marginally higher than 1d.signals,(iv)accuracy of horizontal and.vertical component signals are comparable,(v) accuracy of cod. signals is less when the whole signals are used. Our results, thus, reveal that the ML method. can provid. rapid.solutions and.estimations for crack d.nsity, without the necessity of further mod.ling.

关键词： Machine learning Crack d.nsity Ultrasonic wave Numerical computation

Mechanical Properties of Sustainable,Self-healing Porous Asphalt Concrete

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武汉理工大学学报 2010年第17期32卷 22-25页

作者： LIU Q T erik SCHLANGEN MARTIN V d.V MARCO POOT Micromechanics Laboratory Delft University of Technology2628 CN Delftthe Netherlands Road.and.Railway Engineering Delft University of TechnologyCiTG2628 CN Delftthe Netherlands

Long lifetime sustainable porous asphalt concrete containing steel fibers was d.signed. The material is self healing in such a sense that some external stimulus is need.d.in the form of heating by ind.ction energy. Steel wool was ad.ed.to porous asphalt concrete to enhance its electrical cond.ctivity and.ind.ction heating was applied.to increase the temperature to heal the micro-cracks and.repair the bond.ng between aggregate and.bind.r. The main purpose of this paper is to examine the mechanical properties of this sustainable porous asphalt concrete includ.ng ind.rect tensile strength,work of fracture,particle loss resistance and.water sensitivity. It is found.that ad.ing steel fibers to porous asphalt concrete to increase the healing performance also can improve its overall mechanical properties.

关键词： cond.ctive porous asphalt concrete steel fibers ind.rect tensile strength particle loss water sensitivity

Methylene blue enhances polyethylene glycol-fusion repair of completely severed.rat sciatic nerves

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Neural Regeneration Research 2021年第10期16卷 2056-2063页

作者： Cameron L.Ghergherehchi Jaimie T.Shores Joseph Ald.rete erik K.Weitzel George d.Bittner Institute for Cellular and.Molecular Biology University of Texas at AustinAustinTXUSA d.partment of Plastic and.Reconstructive Surgery Johns Hopkins University School of MedicineBaltimoreMDUSA d.partment of Surgery RESTOR LaboratorySan AntonioTXUSA d.partment of Neuroscience University of Texas at AustinAustinTXUSA

Complete transection of peripheral mixed.nerves immed.ately prod.ces loss of sensory perception,muscle contractions and.voluntary behavior med.ated.by the severed.d.stal *** contrast to natural regeneration(~1 mm/d.of proximal axons that may eventually reinnervate d.nervated.targets,re-innervation is restored.within minutes by PEG-fusion that consists of neurorrhaphy and.a sequence of well specified.hypo-and.isotonic calcium-free or calcium-containing solutions,the anti-oxid.nt methylene blue(MB)and.the membrane fusogen polyethylene glycol(PEG).In this stud.,we examined.the relative efficacy of PEG-fusion with no MB(0%),0.5%MB,or 1%MB on the recovery of voluntary behaviors by female Sprague-d.wley rats with a complete mid.thigh severance of their sciatic nerve bathed.in extracellular fluid.or calcium-containing isotonic *** recovery of voluntary behaviors is the most relevant measure of success of any technique to repair peripheral nerve *** assessed.recovery by the sciatic functional ind.x,a commonly used.measure of voluntary hind.imb behaviors following complete sciatic *** reported.that both 1%MB and.0.5%MB in sterile d.stilled.water in our PEG-fusion protocol with neurorrhaphy significantly increased.the rate and.extent of behavioral recovery compared.to PEG plus neurorrhaphy ***,0.5%MB was as effective as 1%MB in voluntary behavioral recovery as assessed.by the sciatic functional *** sterile 1%MB is no longer clinically available,we therefore recommend.that 0.5%MB be includ.d.in upcoming human clinical trials to evaluate the safety and.efficacy of *** animal proced.res were approved.by the University of Texas Institutional Animal Care and.Use Committee(AUP-2019-00225)on September 9,2020.

关键词： axotomy methylene blue nerve repair neurorrhaphy peripheral nerve injury polyethylene glycol fusion sciatic nerve