简介:InthispaperthemeteorologicalbackgroundfortheformationofplumefromtheforestfireinNortheastChinaon7—8May1987isstated.Thelong-rangeinstantaneousdiffusionparametersarecalculatedbyusingthesatellitephotographoftheplumeswithvisiblelengthrangingfrom100toover500kin.Theresultsofcal-culationshowthattherelationsbetweeninstantaneousdiffusionparameterandtraveltime(upto60000sec.)obeythelawoflinearor3/2power.Inaddition,heatreleasefromthefireonMay7—8estimatedbypuffrisingformulacanmeet,inrespecttotheorderofmagnitude,thevaluegainedonthefieldsurvey.
简介:Inthispaper,wehaveinvestigatedtheproblemoftheconvergencerateofthemultipleintegralwheref∈Cn+1([0,T]n)isagivenfunction,πisapartitionoftheinterval[0,T]and{BtHi,π}isafamilyofinterpolationapproximationoffractionalBrownianmotionBtHwithHurstparameterH<1/2.ThelimitprocessisthemultipleStratonovichintegralofthefunctionf.Inviewofknownresults,theconvergencerateisdifferentfordifferentmultiplicityn.Undersomemildconditions,weobtainthattheuniformconvergencerateis2Hinthemeansquaresense,whereisthenormofthepartitiongeneratingtheapproximations.
简介:3-degree-of-freedom(3-DOF)的一个新分析模型旋转罗盘加速表系统由一个1-DOF驱动器和2-DOF感觉模式组成被介绍。模型构造微分方程由向量分析与系统的每DOF联系了的lumped。因此建立的联合微分方程是为他们在时间和频率领域的回答的解决的经分解。就这些频率反应方程而言,新奇设备设计概念被强迫感觉阶段到零导出,它导致在结构的频率之间的某个关系,从而在系统的表演上引起抑制效果的最小化。而且,现在的旋转罗盘加速表结构的可行性在他们的事件为旋转罗盘行动和线性加速的察觉用一个唯一的差别对待的计划被学习。这个计划把旋转罗盘加速表的提出的解决的短暂解决方案与同步解调和过滤的进程相结合,它导致同相并且系统输出的照部件发信号。这二个部件能在尖运动和线性加速的察觉被利用。获得的分析结果被模拟在MATLAB/Simulink环境验证,并且结果在对对方的优秀同意,这被发现。
简介:Thisarticleprovestheexistenceanduniquenessofsolutiontotwo-parameterstochasticVolterraequationwithnon-LipschitzcoefficientsanddrivenbyBrowniansheet,wherethemaintoolisBihari'sinequalityintheplane.Moreover,wealsodiscussthetimeregularitypropertyofthesolutionbyKolmogorov'scontinuitycriterion.
简介:Ananalysisisperformedtostudytransientfreeconvectiveboundarylayerflowofacouplestressfluidoveraverticalcylinder,intheabsenceofbodycouples.Thesolutionofthetime-dependentnon-linearandcoupledgoverningequationsiscarriedoutwiththeaidofanunconditionallystableCrank–Nicolsontypeofnumericalscheme.Numericalresultsforthesteady-statevelocity,temperatureaswellasthetimehistoriesoftheskin-frictioncoefcientandNusseltnumberarepresentedgraphicallyanddiscussed.Itisseenthatforallflowvariablesasthecouplestresscontrolparameter,Co,isamplified,thetimerequiredforreachingthetemporalmaximumincreasesbutthesteady-statedecreases.
简介:A3DfiniteelementmodelfortheTaizhouYangtzeRiverBridge,thefirsttriple-towerlong-spansuspensionbridgeinChina,isestablishedbasedonthenonlinearfiniteelementsoftwareABAQUS,andthedynamiccharacteristicsofthebridgeareanalyzedusingtheLANCZOSeigenvaluesolutionmethod.Thestudyfocusesontheeffectsofthevertical,lateralandtorsionalstiffnessofthesteelboxgirder,therigidcentralbuckleandtheelasticrestraintsconnectingthetowersandthesteelboxgirderonthedynamiccharacteristicsofthetriple-towersuspensionbridge.Ourresultsshowthat,ingeneral,thedynamiccharacteristicsofthetriple-towersuspensionbridgearesimilartothoseoftwo-towersuspensionbridges.Thevertical,lateralandtorsionalstiffnessofthesteelboxgirderhavedifferenteffectsonthedynamiccharacteristicsoftriple-towersuspensionbridges.Theelasticre-straintshaveamoresignificanteffectonthedynamiccharacteristicsthanthecentralbuckle,anddecreasingthestiffnessoftheelasticrestraintsresultsintheappearanceofalongitudinalfloatingvibrationmodeofthebridge.Also,rigidcentralbuckleshaveagreaterinfluenceonthedynamiccharacteristicsoftriple-towersuspensionbridgesthanonthoseoftwo-towersuspensionbridges.Theresultsobtainedcouldserveasavaluablenumericalreferenceforanalyzinganddesigningsuper-long-spantriple-towersuspensionbridges.
简介:Westudytheleastsquaresestimationofdriftparametersforaclassofstochasticdifferentialequationsdrivenbysmallα-stablenoises,observedatnregularlyspacedtimepointsti=i/n,i=1,···,non[0,1].Undersomeregularityconditions,weobtaintheconsistencyandtherateofconvergenceoftheleastsquaresestimator(LSE)whenasmalldispersionparameterε→0andn→∞simultaneously.TheasymptoticdistributionoftheLSEinoursettingisshowntobestable,whichiscompletelydifferentfromtheclassicalcaseswhereasymptoticdistributionsarenormal.
简介:AbstractBackground:Male sex workers are at high-risk for acquisition of sexually transmitted infections (STIs), including human immunodeficiency virus (HIV). We quantified incidence rates of STIs and identified their time-varying predictors among male sex workers in Mexico City.Methods:From January 2012 to May 2014, male sex workers recruited from the largest HIV clinic and community sites in Mexico City were tested for chlamydia, gonorrhea, syphilis, hepatitis, and HIV at baseline, 6-months, and 12-months. Incidence rates with 95% bootstrapped confidence limits were calculated. We examined potential time-varying predictors using generalized estimating equations for a population averaged model.Results:Among 227 male sex workers, median age was 24 and baseline HIV prevalence was 32%. Incidence rates (per 100 person-years) were as follows: HIV [5.23; 95% confidence interval (CI): 2.15-10.31], chlamydia (5.15; 95% CI: 2.58-9.34), gonorrhea (3.93; 95% CI: 1.88-7.83), syphilis (13.04; 95% CI: 8.24-19.94), hepatitis B (2.11; 95% CI: 0.53-4.89), hepatitis C (0.95; 95% CI: 0.00-3.16), any STI except HIV (30.99; 95% CI: 21.73-40.26), and any STI including HIV (50.08; 95% CI: 37.60-62.55). In the multivariable-adjusted model, incident STI (excluding HIV) were lower among those who reported consistently using condoms during anal and vaginal intercourse (odds ratio= 0.03, 95% CI: 0.00-0.68) compared to those who reported inconsistently using condoms during anal and vaginal intercourse.Conclusions:Incidence of STIs is high among male sex workers in Mexico City. Consistent condom use is an important protective factor for STIs, and should be an important component of interventions to prevent incident infections.
简介:Theproblemoftherobustfaultdetectionfilterdesignfortime-varyingdelaysswitchedsystemsisconsideredintheframeworkofmixedH_-/H_∞.Firstly,theweightedH_∞performanceindexisutilizedastherobustnessperformance,andtheH_-indexisusedasthesensitivityperformanceforobtainingtherobustfaultdetectionfilter.ThenanovelmultipleLyapunov-Krasovskiifunctionisproposedforderivingsufficientexistenceconditionsoftherobustfaultdetectionfilterbasedontheaveragedwelltimetechnique.Byintroducingslackmatrixvariable,thecouplingbetweentheLyapunovmatrixandsystemmatrixisremoved,andtheconservatismofresultsisreduced.Basedontherobustfaultdetectionfilter,residualisgeneratedandevaluatedfordetectingfaults.Inaddition,theresultsofthispaperaredependentontimedelays,andrepresentedintheformoflinearmatrixinequalities.Finally,thesimulationexampleverifiestheeffectivenessoftheproposedmethod.
简介:这份报纸处理一二维(2D)为厚板有热采购的transverselyisotropic和身体的问题强迫。板的上面的表面是与规定表面温度免费的应力,当板的更低的表面在一个僵硬基础上休息时并且热地被绝缘。学习在格林和Naghdi建议的概括thermoelasticity的上下文被执行。为排水量和温度领域的管理方程被使用Laplace和Fourier变换在Laplace-Fourier变换领域获得。双变换的倒置数字地被做。Laplace变换的数字倒置基于Fourier系列扩大被做。数字计算为镁(Mg)被执行,并且结果图形地被介绍。各向同性的材料(Cu)的结果数字地被获得并且图形地介绍了与横着各向同性的材料(Mg)的那些相比。身体力量的效果也被学习。
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简介:Thecalculationofsettlingspeedofcoarseparticlesisfirstlyaddressed,withacceleratedStokesiandynamicswithoutadjustableparameters,inwhichfarfieldforceactingontheparticleinsteadofparticlevelocityischosenasdependentvariablestoconsiderinter-particlehydrodynamicinteractions.Thesedimentationofasimplecubicarrayofsphericalparticlesissimulatedandcomparedtotheresultsavailabletoverifyandvalidatethenumericalcodeandcomputationalscheme.TheimprovedmethodkeepsthesamecomputationalcostoftheorderO(NlogN)asusualacceleratedStokesiandynamicsdoes.Then,morerealisticrandomsuspensionsedimentationisinvestigatedwiththehelpofMontCarlomethod.Thecomputationalresultsagreewellwithexperimentalfitting.Finally,thesedimentationoffinercohesiveparticle,whichisoftenobservedinestuaryenvironment,ispresentedasafurtherapplicationincoastalengineering.
简介:不可思议地使不安的传送对流散开方程的Acoupled系统被考虑。每个方程的领先的条款被一个小积极参数乘,但是这些参数可以有不同大小。系统的答案有重叠并且交往的边界层。这些层的结构被分析,并且这导致是平常的Shishkin网孔的变体的一个piecewise制服网孔的构造。在一个迎风的差别计划被证明几乎一阶精确的这个网孔上,一致地在两个小参数。我们在场数字实验到的结果证实我们的理论结果。
简介:Thispaperpresentstheresultsofaluminumsurfacetreatmentbydiffusecoplanarsurfacebarrierdischarge.Thegoalsaretostudytheeffectivenessoftheplasmatreatmentandthedependenceofitsefficiencyonoperationparameters,suchassample-to-electrodedistance,treatmenttimeorgasatmosphere.Threetypesofaluminummaterials(bricks,sheetsandthinfilms)weretestedtoensurethereliabilityofthetreatment.Thechangesinthesurfacepropertieswerecharacterizedbythesurfacefreeenergy,atomicforcemicroscopy,attenuatedtotalreflectanceFouriertransforminfraredspectroscopy(ATRFTIR)andX-rayphotoelectronspec-troscopy(XPS).Theinfluenceofagingeffectonthetreatmentwasalsomeasuredanddiscussed.