简介：在强风和影响负担下面造结构的进步倒塌在整个世界吸引了大注意。进步倒塌分析为对进步倒塌造结构爆炸并且影响负担的一个经济、安全的图案是必要的。因为进步倒塌的灾难的性质和构造或翻新大楼抵抗它的潜在地高的费用，进步倒塌分析方法是可靠的，是必要的。为工程师，他们执行进步倒塌评估的方法论不必仅仅精确、简明，而且容易快被使用并且工作。因此，许多研究人员一直在花大量在最近开发可靠、有效、直接的进步倒塌分析方法的努力。在现在的纸，在文学可得到的当前的进步倒塌分析方法被考察。他们的适用性，适用性和可靠性被讨论。我们为在强风负担下面的增强的具体框架的进步倒塌分析的最近的建议新方法也被介绍。

简介：Thisstudyexaminestheurbanpopulationoftourismpractitioners'perceptionsofeconomic,environmental,andsocialimpactsoncultural,convention,andsporttourismmayhaveinHaikouandSanya,Hainan,China.ThestudyusesamodifiedUrbanTourismImpact(UTI)toexamineeconomic,environmental,andsocialperceivedimpacts.Analysisofthedataincludestestingthreemodelsofstructuralrelationshipsbetweentourismimpactsandsupportfordevelopmentineachofthetourismmarketsub-divisionsthroughaconfirmatoryfactoranalysis.Theresultsofthisstudyshowthatthepositiveeconomicimpactsconsistentlyexertinfluenceonpredictingsupportfortourismdevelopmentinallthreemodels.However,thesocialimpactsplayagreaterexplanatoryrolewithallthreemarketsegment,thenegativeenvironmentalimpactsplayaroleindeterminingsupportforsporttourismonly.Differenceshavebeenfoundwiththosewithahighereducationlevelinpredictingsupportforculturaltourism,butnotconventionorsporttourism.

简介：

简介：ByusingtheformuladerivedinPart(Ⅰ),theinstantresponseofanunrestrainedplanarframestructuresubjectedtotheimpactofamovingrigid-bodyareevaluatedandanalysed.Theimpactforce-timehistorybetweenthestructureandthemovingrigid-body,shearforceandbendingmomentdistributionalongthebeams,axialforcedistributionalongthebarswerecalculated.Thewavepropagationphenomenaofthelongitudinalwaveinthebars,theflexuralandshearwavesinthebeamswerealsoanalysed.Thenumericalresultsshowthatthetimedurationofimpactforceiscontrolledbytheflexuralwaveandthelongitudinalwave;thesheareffectinbeamsshouldnotbeneglectedintheimpactresponseanalysisofstructures.

简介：

简介：SustainableeconomicrecoveryintheU.S.hascreatedafavorableenvironmentfortheFederalReserve(Fed)’staperingpolicy,butthisoperationfacesmanydifferenttypesofrisk.ChinashouldseizethecurrentopportunitywhiletheFedtapersoperationstocarveoutcountermeasuresinordertowithstandeconomicriskandenhanceitscapacitytowardofffinancialshock.

简介：

简介：Indesignphases,expansionjointsarerequiredtohavemovementcapacity,bearingcapacityforstaticanddynamicloading,watertight,lownoiseemissionandtrafficsafety.Onthebasisofthefactthatfailureduetodynamicloadingisthemainreasonfortheobserveddamages,attentionisfocusedonthebearingcapacityfordynamicloadinggovernedbyimpact,becauseitdiffersfromthestaticloading.Inthisstudy,fromtheviewpointofdurability,experimentalstudiesfordynamicbehaviorwereconductedforaluminiumalloyexpansionjointswithperforateddowels.Thevalidityoftheperforateddowelsagainsttrafficimpactloadingwasconfirmedbybothexperimentalandnumericalstudies.

简介：Byusingthewell-developedintegraltransformmethodology,thedynamicresponseofstressandelectricdisplacementaroundafinitecrackinaninfinitepiezoelectricstripareinvestigatedunderarbitrarydynamicanti-planeloads.Thedynamicstressintensityfactorsandelectricdisplacementareobtainedanalytically.Itisshownthatthedynamiccrack-tipstressandelectricfieldstillhaveasquare-rootsingularity.Numericalcomputationsforthedynamicstressintensityfactorshowthattheelectricloadhasasignificantinfluenceonthedynamicresponseofstressfield.Thehighertheratioofthecracklengthtothewidthofthestrip,thehigherthepeakvalueofthedynamicstressintensityfactoris.Ontheotherhand,thedynamicresponseoftheelectricfieldisdeterminedsolelybytheappliedelectricload.Theelectricfieldwillpromoteorretardthepropagationofthecrackdependingonthetimeelapsesincetheapplicationoftheexternalelectro-mechanicalloads.

简介：AseveretyphoonUtor,occurringbetweenJuly3and8,2001,broughtheavyrainfall,strongwindandstormsurge.UtorwasresponsiblefortremendousdestructionandeconomiclossesinPhilippines,TaiwanandGuangdong.Anair-seamodelsystem(MM5andPrincetonOceanModel(POM))wasbuilttosimulatemeteorologicaldynamicsandoceancirculationintheSouthChinaSea(SCS).InthePOMtheoutputofMM5wasusedastheinputdata.Withanincreasednumberofverticallevels,ahigh-resolutionplanetaryboundarylayerschemeandupdatedlanduse/vegetationdata,theaccuracyofcomputingwind,temperatureandothermeteorologicalfieldsareimprovedinnearsurfaceandupperlevelsinMM5simulations.ThesimulatedtrajectoryandwindspeedofUtorareclosetotheobservedresults.ThesimulateddistributionofrainfallisaccordedwellwithmeasureddatainthePearlRiverDelta(PRD)area.AtdifferentmeteorologicalstationsinHongKong,thewind,temperatureandseasurfacepressurearewellsimulated.Thesimulatedoceansurfacecurrentandsurfacetemperaturefieldshaveanobviousrightward-biasedresponsetothetyphoonUtor,andthemaximumvelocityandthelowesttemperatureregionappearinthe30kmoftherightsideofthetyphoontrack.ThetyphoonUtorcouldmakethewater50munderthesurfaceoceanunwelltosurfaceandtheoceansurfacetemperaturedecreasebyabout2°C.

简介：

简介：

简介：Thisletterpresentsatheoreticalmodelofthenormal(head-on)collisionsbetweentwosoftspheresforpredictingtheexperimentalcharacteristicofthecoefficientofrestitutiondependentonimpactvelocity.Afterthecontactforcelawbetweenthecontactedspheresduringacollisionisphenomenologicallyformulatedintermsofthecompressionoroverlapdisplacementunderconsiderationofanelastic-plasticloadingandaplasticunloadingsubprocesses,thecoefficientofrestitutionisgainedbythedynamicequationofthecontactprocessonceaninitialimpactvelocityisinput.Itisfoundthatthetheoreticalpredictionsofthecoefficientofrestitutionvaryingwiththeimpactvelocityarewellinagreementwiththeexistingexperimentalcharacteristicswhicharefittedbytheexplicitformula.

简介：运用地理信息系统和遥感等手段，研究了北京市大兴县从５０年代至９０年代景观格局变化及其对土地荒漠化的影响．结果显示，从５０年代至９０年代，旱地和荒地的面积逐渐减少，水浇地、林地、菜地、果园和各类特殊用地的面积逐渐增加．景观多样性、均匀度和城市化指数不断上升，景观优势指数逐渐下降．大兴县景观斑块的形状比较简单，各斑块的分维数较低，不同斑块的分维数的差异较小．由于自然和人为干扰的双重影响，从５０年代至９０年代，大兴县的景观格局已经发生了根本的变化．伴随着这些变化，该县的生态环境和整体面貌发生了明显的改变，土地荒漠化得到了控制，生态环境有了很大改善．

简介：TheimpactofpHchangesonmicrobialbiomasscarbon(Cmic)andmicrobialbiomassphosphorus(Pmic)wereexaminedfor3redsoilsundercitrusproductionwithdifferentlengthsofcultivation.SoilpHsignificantlyaffectedCmicandPmic.TheCmicandPmicchanges,asafunctionofsoilpH,appearedtofollowanormaldistributionwiththeoriginalsoilpHvalueattheapexandaspHincreasedordecreasedcomparedtotheoriginalsoilpH,CmicandPmicdeclined.Moreover,therewerecriticalpHvaluesatbothextremes(3.0ontheacidicsideand8.0to8.5onthealkalineside),beyondwhichmostofmicroorganismscouldneversurvive.TheeffectofpHonCmicandPmicwasalsorelatedtotheoriginalsoilpH.ThehighertheoriginalsoilpHwas,thelessCmicorPmicwereaffectedbypHchange.ItissuggestedthatsoilmicroorganismsthatgrowinasoilenvironmentwithamoreneutralsoilpHrange(I.e.pH5.5-7.5)mayhaveagreatertolerancetopHchangesthanthosegrowinginmoreacidicormorealkalinesoilpHconditions.

简介：Theobliquepenetrationperformanceoflightweighthybrid-coredsandwichplatesareinvestigatednumerically.Tocomposethehybrid-core,ceramicprismsareinsertedintopyramidalmetallatticetrussesandfixedusingepoxyresin.Three-dimensionalfiniteelementsimulationsarecarriedoutforthehybridcoredsandwichimpactedat15°,30°,45°,and60°obliquitybyahemisphericalprojectile.Theballisticlimit,theenergyabsorbedbytheconstitutingelements,andthecriticalobliqueanglearequantified.Thephysicalmechanismsunderlyingthefailureandtheinfluenceoffundamentalsystemparametersareexplored.Theangleofobliquityisfoundtohavesignificantinfluenceontheballistictrajectoryanderosionoftheprojectile,thusitisimportantfortheimpactresponseandpenetrationresistanceofthesandwich.Forobliqueanglesequaltoorlargerthan45°,theprojectilemovesmainlyhorizontallyandcannoteffectivelypenetrateacrossthesandwich.

简介：Inthepost-ColdWarera,CentralAsia'suniqueandimportantgeo-politicalandeconomicvaluesarebeinghighlightedandareincreasinglybecomingthefocusofcontentionamongbigpowersandregionalpowers.Itprovidesbothopportunitiesandchallenges.ToturnchallengesintoopportunitiesandconsolidateandmakebestuseoftheopportunitiesshouldbecometheprioritygoalofChina'sCentralAsiapolicy.

简介：

简介：在一样的穿入条件下面的不同目标的穿入(DOP)的深度的比率根据不同目标的DOP的更少的公式由非可变形的射弹渗透了的尺寸被调查。结果证明各种各样的目标可以等价于对方。等价的适用的范围和目标替换的可行性被集成可得到的测试数据讨论。

简介：目的:探讨在不同表面上跑步对足底压力和胫骨加速度的影响。方法:13位男性跑步者被要求分别在水泥地、塑胶跑道、天然草地、跑步机以及配备EVA缓冲衬垫物的跑步机上以12km/h的速度进行慢跑。用足底压力测试系统和安放在胫骨粗隆的加速度计,记录和分析足底压力与胫骨冲击的特点。结果:第一和第二足底压力峰值(发生时间)、压力时间积分、峰值压力分布在混凝土、塑胶、草地和正常的跑步机的表面间没有明显差异。在5种不同测试表面下,峰值加速度正值也无显著差异。但相比于混凝土表面,在配备EVA缓冲衬垫物的跑步机上跑步能明显减小在冲击阶段的足底压力第一峰值和压力积分(p<0.05)。上述结果可进一步归因为足后跟区域峰值压力下降(P<0.05)。结论:运动表面和下肢冲击之间也许并无必然关系。然而值得注意的是,在解释足底压力的表现及将其运用到陆地表面的跑步运动中时应考虑不同跑步机表面的影响。