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1.
IntroductionAsRef.[1 ]pointedout,inaturbinecascadewithtipclearance,mostofthesingularpointsandseparationlines,duetotheeffectoftheleakageflow ,arelocatedattheupperhalfspan(especiallyinitssuctionsurfacecorner) ,whichconsequentlyleadstoworsetheaerodynamiccharac…  相似文献   

2.
Thethreshold_crossingofstochasticprocessesisaproblemoftenencounteredinthestudyofvariousphysicalphenomena .Theterm ,threshold_crossing ,isusedtoindicateacertainfixedvaluebeingcrossedbytheoscillatingrealizationζ(1) (t)ofastochasticprocessζ(t) ,asshownbythetypi…  相似文献   

3.
IntroductionInthestrengthofmaterials[1],inordertoeliminatetheadditionaltorsioninathin_walledcylinderwithopencross_sectionunderbendingbyatransverseforce,itissufficienttoremovethetransverseforceatthebendingcenter.Thereforeanapproximatemethodtocalculatethe…  相似文献   

4.
Self-Similar Solutions of Fracture Dynamics Problems on Axially Symmetry   总被引:4,自引:0,他引:4  
IntroductionCompositematerialsarealmostmadeupoffiberandmatrixwithanisotropicmacrostructure ,whosevariousstructuresareeasytoappearapenny_shapedmicrocrackintheprocessoftheirwork.Whenitextendsgradually ,thestructurewillleadtodestruction .Itiswell_knownthat…  相似文献   

5.
IntroductionForgeomaterialssuchasrockandconcrete,thefrictionalslidingalongmicrocracksurfacesisassociatedwiththeplasticitymodeldescribedbytheMohr_Coulombtheory ;moreovercrackpropagationcorrespondstodamagegrowth .Thecouplingofdamageandplasticityofaphenom…  相似文献   

6.
IntroductionWhenastaticallyindeterminatetrusshasalowerloadcapacityowingtothetremendousdifferenceofinternalforcesofbars,itdoesn’tlayingoodworkingstate.Toincreasethecapacity ,cross_sectionalareasofelementsareoptimizedbytheprogrammingmethodandthecriterion…  相似文献   

7.
IntroductionThebasicfunctionofthemicrocirculationistoallowrapidexchangeofwater,gases,nutrientsandwasteproductsbetweenthebloodandtissuecells.Amicrocirculationunitthereforeconsistsofmicrovessels(arterioles,capillaries,venules,thoroughfaresandarteriole_…  相似文献   

8.
IntroductionAnaturalorartificialmaterialisusuallymicroscopicallyheterogeneousandownsacertainmicrostructurecomprisingthematerialconstitutions (crystalloid ,dislocations ,phasetransformations,micro_cracks,voids,fibers,inclusions) .Itisnotsurprisingthatanumbe…  相似文献   

9.
IntroductionInthree_dimensionalphotoelasticity ,photoplasticity ,simulatingexperimentsofbuildingstructuresandphysicalsimulationsofmetalformingprocesses,thereiseachandallanidenticalproblemsforstudy ,thatis,greaterrorsareusuallycausedbythesuppositionthatth…  相似文献   

10.
IntroductionOneoftheprimaryproblemsingoetechnicalengineeringistoconstructasoilconstitutivemodelapplicabletogeneral 3_Dstressstates.Althoughmanytypesofconstitutivemodelshavebeenproposed ,fewcantakeproperaccountofthedirectionalchangeofstressvector (i.e .,ro…  相似文献   

11.
3-D Fracture Propagation Simulation and Production Prediction in Coalbed   总被引:2,自引:0,他引:2  
NomenclatureA(x,t)—Cross_sectionareaoffractureattimetandsitex,m2 ;Bg,Bw —Coalbedgasandwatervolumefactor,di mensionless;b—Langmuirfactor,(MPa) - 1 ;Cg,CR,Cw —Coalbedgas,rockandwatercom pressibilitycoefficient,(MPa) - 1 ;Cp —Sandratio ,dimensionless;Ct(x ,t)—Totalfracturin…  相似文献   

12.
Althoughtheconstrainedtwistproblemsofthin_wallstraightbarsofisotropicand/oranisotropicmaterials,withclosedoropencross_sections,havebeenwellsolved[1~3],forspatialcurvedbarsofthistypeofproblemstherehasnotbeenanysatisfactorysolutionuptonow.Thisproblemis…  相似文献   

13.
IntroductionAnunevendistributionoftheclearanceofvane_tipalongthecircumferenceorientationcausedbytherelativeeccentricitybetweenimpellerandcylinderofsteamturbinewillresultunequalpneumaticforceofthevanesatthesamestage .Asaresult,inadditiontoatorque,thetra…  相似文献   

14.
IntroductionThecomprehensivemathematicalmodeldevelopedinthefirstpartofthispaper[1]containsdozensofcoupledequationsthatformalargenonlinearequationsystem.Herewecombineanalyticalandnumericalmethodstosolveitanddiscussandanalyzesomeimportantproblemsinmicroc…  相似文献   

15.
IntroductionFatiguefractrueisaprimarymodeoffailureformetallicstructuresandmechanicalsystemssubjectedtovariousdynamicloads.Atthebeginningofservice,someinherentdefectssuchasmicrocracks,weldingdefects,notches,voidsetc.existinmanystructuresorelements.Thesed…  相似文献   

16.
IntroductionThestudyofrandomparametricexcitedsystemsaremoreimportantthanthatofrandomexternalexcitedones,andaretheoreticallymoredifficultespeciallywhentheexcitationsarenarrow_bandrandomprocesses[1].Inthecasewhenthesystemsareexcitedbycombineddeterministi…  相似文献   

17.
IntroductionThetransientphenomenaofdynamicproblemsandthemannerstotreatthemaregenerallyrelatedtothespectralcharacteristicsofexcitation .Onemayomitpropagatingwavesifrelativelylowerfrequenciesgoverntheresponsesintheproblemssuchasseismicresponsesandrespon…  相似文献   

18.
IntroductionSinceDienes(1979),NagtegalandDeJong(1982)etalhadocasionalyfoundthephenomenaofsimpleshearoscilationusingthegeneral...  相似文献   

19.
IntroductionAsageneralizationoftheclasicalfieldtheory,nonlocalfieldtheorycanbeusedasthetheoreticalbaseinmacro_micromechanicsb...  相似文献   

20.
IntroductionTheRef.[1 ]pointedoutthatsometypicalnonlinearwaveequationspossessedfivecommonfactors,whichwerewithsolitarysolutions,infiniteconservedlaws,exactlysolvableevolutionequationsbytheuseofinversescatteringmethod .B cklundtransformations,beingreducedto…  相似文献   

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