简介：Theperfectlymatchedlayer(PML)isaneffectivetechniquefortruncatingunboundeddomainswithminimalspuriousreflections.Afluidparabolicequation(PE)modelapplyingPMLtechniquewaspreviouslyusedtoanalyzethesoundpropagationprobleminarange-dependentwaveguide(LuandZhu,2007).However,LuandZhuonlyconsideredastandardfluidPEtodemonstratethecapabilityofthePMLanddidnottakeimprovedone-waymodelsintoconsideration.Theyapplieda[1/1]Padéapproximanttotheparabolicequation.Thehigher-orderPEsaremoreaccuratethanstandardoneswhenaverylargeanglepropagationisconsidered.Asforrange-dependentproblems,thetechniquestohandletheverticalinterfacebetweenadjacentregionsaremainlyenergyconservingandsingle-scattering.Inthispaper,thePMLtechniqueisgeneralizedtothehigherorderelasticPE,asistothehigherorderfluidPE.Thecorrectionofenergyconservingisusedinrange-dependentwaveguides.Simulationismadeinbothacousticcasesandseismo-acousticcases.Range-independentandrange-dependentwaveguidesarebothadoptedtotesttheaccuracyandefficiencyofthismethod.ThenumericalresultsillustratethataPMLismuchmoreeffectivethananartificialabsorbinglayer(ABL)bothinacousticandseismo-acousticsoundpropagationmodeling.

简介：Verticallyexploringthecharacteristicsofthetyphoonboundarylayer(TBL)playsanimportantroleinrecognizingtyphoonstructure.TheboundarylayerradialdirectionandtangentialwindcharacteristicsofTyphoonUsagibasedontheobservationaldataofthreeboundarylayerwindprofilerstationsalongtherouteofTyphoonUsagi(No.1319)andbycombiningwithsoundingdata.Theresultsshowthat:(1)maximumtangentialwindappearsinthevicinityoftheeyeareaofUsagi,anditbasicallymaintainsaheightofaround1800mwhenUsagikeepsastrongtyphoonlevel,withtherapidlydecreasingstrengthofUsagiafteritlands,thespeedofthemaximumtangentialwindanditsverticalrangebothdecrease;(2)theheightofthemaximumtangentialwindisclosetothatoftheinflowlayertopofthetyphoon,andisgreaterthanthatoftheboundarylayerestimatedonthebasisofRichardsonnumberorpotentialtemperaturegradient,whiletheheightofmixedlayerjudgedonthebasisofthesignal-to-noiseratio(SNR)oritsgradientisusuallylow;(3)thetheboundarylayerheightcanreachhigherthan2100mbeforeUsagilands.Whenthetyphoonleveloraboveisachieved,theboundarylayerheightobservedbyvariousstationsdoesnotchangemuch,basicallystayingatbetween1200and1600m.WiththedecreasingstrengthofUsagiafteritslandfall,theboundarylayerheightrapidlydrops.

简介：ThispaperpresentsthenumericalinvestigationofthedistributionofinertialsedimentparticlesintheturbulentboundarylayerofanopenchannelflowwiththeparticleStokesnumberrangingfrom0.6to20.4.Themethodologyisacombinationofthreenumericalapproaches,i.e.directnumericalsimulationofturbulentflow,thepoint-particleimmersedboundarymethod,andthediscreteparticlemethod.ByapplyingtheVorono?analysis,thepreferentialconcentrationcharacteristicsofsedimentparticleswereinvestigatedquantitatively.ItwasfoundthatthenormalizedareaoftheVorono?cellsfollowsalognormalparticledistribution.Theinertialsedimentparticlesdistributedunevenlyintheturbulentboundarylayerandtheunevenness,governedbytheparticleStokesnumber,wasmoresignificantastheparticleStokesnumberapproachesunity.Theinertialsedimentparticlesintheturbulentboundarylayeraccumulatedpreferentiallyinstreamwise-alignedstreakystructuresandthispatternwaslesssignificantwithincreasingparticleStokesnumber.

简介：Thehighstrengthlow-alloysteelsareweldedbyunderwaterwetweldingwithstainlesssteelelectrodes.Themicrostructuralandelectrochemicalcorrosionstudyofbasemetal(BM),weldzone(WZ)andheataffectedzone(HAZ)arecarriedouttounderstandtheinfluenceofthecorrosionproductlayergeneratedonthehighstrengthlow-alloysteelsweldedbyunderwaterwetweldingwithstainlesssteelelectrodes,methodsusedincluding,potentiodynamicpolarization,electrochemicalimpedancespectroscopy(EIS)andscanningelectronmicroscope(SEM).TheresultsindicatethattheWZactsasacathodeandthereisnocorrosionproductonitthroughouttheimmersionperiodinseawater.TheHAZandBMactsasanodes.ThecorrosionratesoftheHAZandBMchangewiththeimmersiontimeincreasing.Intheinitialimmersionperiod,theHAZhasthehighestcorrosionratebecauseithasacoarsetemperedmartensitestructureandtheBMexhibitesamicrostructurewithveryfinegrainsofferriteandpearlite.Afteraperiodofimmersion,theBMhasthehighestcorrosionrate.ThereasonisthatthecorrosionproductlayerontheHAZisdenseandhasabetterprotectivepropertywhilethatontheBMislooseandcannotinhibitthediffusionofoxygen.

简介：Basedonobservationsofurbanmassconcentrationoffineparticulatemattersmallerthan2.5μmindiameter(PM_(2.5)),groundmeteorologicaldata,verticalmeasurementsofwinds,temperature,andrelativehumidity(RH),andECMWFreanalysisdata,themajorchangesintheverticalstructuresofmeteorologicalfactorsintheboundarylayer(BL)duringtheheavyaerosolpollutionepisodes(HPEs)thatoccurredinwinter2016intheurbanBeijingareawereanalyzed.TheHPEsaredividedintotwostages:thetransportofpollutantsunderprevailingsoutherlywinds,knownasthetransportstage(TS),andthePM_(2.5)explosivegrowthandpollutionaccumulationperiodcharacterizedbyatemperatureinversionwithlowwindsandhighRHinthelowerBL,knownasthecumulativestage(CS).DuringtheTS,asurfacehighliessouthofBeijing,andpollutantsaretransportednorthwards.DuringtheCS,astableBLformsandischaracterizedbyweakwinds,temperatureinversion,andmoistureaccumulation.Stableatmosphericstratificationfeaturedwithlight/calmwindsandaccumulatedmoisture(RH>80%)below250matthebeginningoftheCSiscloselyassociatedwiththeinversion,whichisstrengthenedbytheconsiderabledecreaseinnear-surfaceairtemperatureduetotheinteractionbetweenaerosolsandradiationaftertheaerosolpollutionoccurs.AsignificantincreaseinthePLAM(ParameterLinkingAerosolPollutionandMeteorologicalElements)indexisfound,whichislinearlyrelatedtoPMmasschange.Duringthefirst10hoftheCS,themorestableBLcontributesapproximately84%oftheexplosivegrowthofPM_(2.5)mass.Additionalaccumulatednear-surfacemoisturecausedbythegroundtemperaturedecrease,weakturbulentdiffusion,lowBLheight,andinhibitedverticalmixingofwatervaporisconducivetothesecondaryaerosolformationthroughchemicalreactions,includingliquidphaseandheterogeneousreactions,whichfurtherincreasesthePM_(2.5)concentrationlevels.Thecontributionofthesereactionmechanisms

简介：为弥补测高数据在近海区域因为编辑准则被剔除而导致近海测量数据质量不高的缺点,利用5参数模型的两种形式和Ice-2模型对Jason-2卫星在中国南海部分海域的海洋回波波形进行了波形重跟踪的研究,并选择20个海洋回波波形,依据最小二乘原理进行计算、分析、对比,发现5参数模型的指数形式的结果和Ice-2模型结果非常接近.研究结果表明,在开阔的海域,对Jason-2波形进行3种方法波形重跟踪时,可以优先考虑Ice-2模型.波形重跟踪技术能够提高卫星测高数据利用率,为科学研究提供可靠的数据保障.

简介：整理DSC2型称重式降水传感器在业务运行中出现的问题,对DSC2型称重式降水传感器存在的采集器连接、量筒内壁粘雪、小雨时的缺测等问题进行分析。提出提高DSC2型称重式降水传感器运行稳定性的方法,提升其监测的准确性、时效性;提高观测数据的可用性的相应建议。

简介：Thetyphoon,asamaturetropicalcyclonethatdevelopsinthewesternpartoftheNorthPacificOceanwithhighwindspeedandheavyrainfall,isoneofthemostlethalandcostlyofnaturaldisastersforthedenselypopulatedcountriesofEastAsia.Itcanbeeasilydetectedbyspace-bornesensorsoperatedatmicrowave,visibleorinfraredbands(Liuetal.,2014).SyntheticApertureRadar(SAR)is

简介：Aregionalsurfacecarbondioxide(CO_2)fluxinversionsystem,theTan-Tracker-Region,wasdevelopedbyincorporatinganassimilationschemeintotheCommunityMultiscaleAirQuality(CMAQ)regionalchemicaltransportmodeltoresolvefine-scaleCO_2variabilityoverEastAsia.Theproperorthogonaldecomposition-basedensemblefour-dimensionalvariationaldataassimilationapproach(POD-4DVar)isthecorealgorithmforthejointassimilationframework,andsimultaneousassimilationsofCO_2concentrationsandsurfaceCO_2fluxesareappliedtohelpreducetheuncertaintyininitialCO_2concentrations.ApersistencedynamicalmodelwasdevelopedtodescribetheevolutionofthesurfaceCO_2fluxesandhelpavoidthe'signal-to-noise'problem;thus,CO_2fluxescouldbeestimatedasawholeatthemodelgridscale,withbetteruseofobservationinformation.Theperformanceoftheregionalinversionsystemwasevaluatedthroughagroupofsingle-observation-basedobservingsystemsimulationexperiments(OSSEs).TheresultsoftheexperimentssuggestthatareliableperformanceofTan-Tracker-Regionisdependentoncertainassimilationparameterchoices,forexample,anoptimizedwindowlengthofapproximately3h,anensemblesizeofapproximately100,andacovariancelocalizationradiusofapproximately320km.Thisisprobablyduetothestrongdiurnalvariationandspatialheterogeneityinthefine-scaleCMAQsimulation,whichcouldaffecttheperformanceoftheregionalinversionsystem.Inaddition,becauseallobservationscanbeartificiallyobtainedinOSSEs,theperformanceofTan-Tracker-RegionwasfurtherevaluatedthroughdifferentdensitiesoftheartificialobservationnetworkindifferentCO_2fluxsituations.TheresultsindicatethatmoreobservationsiteswouldbeusefultosystematicallyimprovetheestimationofCO_2concentrationandfluxinlargeareasoverthemodeldomain.TheworkpresentedhereformsafoundationforfutureresearchinwhichathoroughestimationofCO_2fluxvariability

简介：于2016年6-11月,在辽河口盘锦市湿地科学研究所基地的芦苇（Phragmitesaustralis）盐沼、笔架岭的盐地碱蓬（Suaedasalsa）盐沼和光滩中,采用静态箱-气相色谱法,采集气体样品,在实验室中,测量和计算出气样的CO2浓度,估算CO2排放通量;分析CO2排放通量与土壤温度、氧化还原电位、pH和电导率等环境因子的关系。结果表明,辽河口芦苇盐沼、盐地碱蓬盐沼（涨潮前）和光滩（涨潮前）CO2排放通量平均值分别为（1187.7±649.0）mg/（m^2·h）、（362.4±146.1）mg/（m^2·h）和（91.1±21.1）mg/（m^2·h）。3种类型湿地CO2排放通量差异显著（n=24,p〈0.01）,芦苇盐沼CO2排放通量最高,光滩的CO2排放通量最低。在涨潮中,盐地碱蓬盐沼和光滩的CO2排放通量平均值分别为（127.9±90.9）mg/（m^2·h）和（45.8±21.1）mg/（m^2·h）,显著低于涨潮前的CO2排放通量（n=24,p〈0.01）。各类型湿地CO2排放通量与土壤电导率显著负相关（n=24,p〈0.01）,说明土壤盐分是影响不同类型湿地CO2排放通量的关键环境因子。

简介：AsshaleexploitationisstillinitsinfancyoutsideNorthAmericamuchresearcheffortisbeingchannelledintovariousaspectsofgeochemicalcharacterizationofshalestoidentifythemostprospectivebasins,formationsandmaptheirpetroleumgenerationcapabilitiesacrosslocal,regionalandbasin-widescales.Themeasurementoftotalorganiccarbon,distinguishingandcategorizingthekerogentypesintermsoil-proneversusgas-prone,andusingvitrinitereflectanceandRock-Evaldatatoestimatethermalmaturityarestandardpracticeintheindustryandappliedtosamplesfrommostwellboresdrilled.Itisthetrendsofstableisotopesratios,particularlythoseofcarbon,thewetnessratio(C1/∑(C2+C3)),andcertainchemicalbiomarkersthathaveprovedtobemostinformativeaboutthestatusofshalesasapetroleumsystem.Thesedatamakeitpossibletoidentifyproduction'sweet-spots',discriminateoil-,gas-liquid-andgas-proneshalesfromkerogencompositionsandthermalmaturities.Rolloversandreversalsofethaneandpropanecarbonisotoperatiosareparticularlyindicativeofhighthermalmaturityexposureofanorganic-richshale.Comparisonsofhopane,streraneandterpanebiomarkerswithvitrinitereflectance(Ro)measurementsofthermalmaturityhighlightdiscrepanciessuggestingthatRoisnotalwaysareliableindicatorofthermalmaturity.Majorandtraceelementinorganicgeochemistrydataandratiosprovidesusefulinformationregardingprovenance,paleoenvironments,andstratigraphic-layerdiscrimination.Thisreviewconsidersthedatameasurement,analysisandinterpretationoftechniquesassociatedwithkerogentyping,thermalmaturity,stableandnon-stableisotopicratiosforrocksandgasesderivedfromthem,productionsweet-spotidentification,geochemicalbiomarkersandinorganicchemicalindicators.Italsohighlightsuncertaintiesanddiscrepanciesobservedintheirpracticalapplication,andthenumerousoutstandingquestionsassociatedwiththem.

简介：为了揭示福州市绿地土壤重金属含量、来源及成因,利用电感耦合等离子体质谱仪（ICP-MS）测定了福州市市区不同绿地功能区土壤重金属的含量,采用单因子污染指数法和内梅罗综合污染指数法对土壤重金属污染水平进行评价,并分析了土壤重金属污染的主要来源。结果表明,福州市不同绿地功能区土壤重金属含量已有一定程度的积累,Cr、Co、Ni、Cu、Zn和Pb等6种重金属元素在4类功能区中均有不同程度的污染,比如Cr、Co、Ni、Cu、Zn和Pb重金属最大含量分别为100.62mg·kg^-1（化工路）、15.10mg·kg^-1（阳光城小区）、24.37mg·kg^-1（浦上大道）、59.04mg·kg^-1（南二环）、227.11mg·kg^-1（化工路）、169.85mg·kg^-1（化工路）;单因子污染指数评价表明,Co、Zn和Pb3种元素在4类绿地功能区达到轻污染,Zn和Pb的污染更严重;综合污染评价中,不同绿地功能区重金属污染程度依次为道路绿地〉居住区绿地〉单位绿地〉公园绿地。福州城市土壤重金属污染来源较复杂,公园绿地土壤重金属污染主要来自居民、游客所产生的丢弃物;单位绿地和居民区绿地土壤重金属污染主要来自生活垃圾;道路绿地土壤重金属含量主要来自交通运输。就重金属元素而言,Cr、Cu、Zn、Pb元素主要受交通运输影响,居民生活影响次之;Co、Ni元素主要受居民生活影响。

简介：以滇西北碧塔海泥炭沼泽土壤为研究对象,通过野外测量和室内分析相结合的方法,研究牦牛（Bosmutus）践踏和牦牛粪影响下的土壤总有机碳含量、全氮含量和N_2O排放通量。结果表明,牦牛践踏显著抑制了土壤N_2O的排放;牦牛粪的输入促进了土壤N_2O的排放,且牦牛粪分解前期是N_2O排放的高峰期。在0~30cm深度土层内,牦牛放牧使土壤总有机碳含量增加,牦牛践踏和牦牛粪都促进了土壤总有机碳含量的增加,增加比例分别为39.27%和12.19%;随着土壤深度的增加,粪斑样方土壤总有机碳含量显著减小,践踏样方土壤总有机碳含量略有增加。牦牛放牧使土壤全氮含量增加,牦牛践踏和牦牛粪都促进了土壤全氮含量的增加,增加比例分别为50.56%和12.76%;随着土壤深度的增加,践踏样方和粪斑样方土壤全氮含量都在减小。

简介：Newsatellite-derivedlatentandsensibleheatfluxesareperformedbyusingWindSatwindspeed,WindSatseasurfacetemperature,theEuropeanCentreforMedium-rangeWeatherForecasting(ECMWF)airhumidity,andECMWFairtemperaturefrom2004to2014.The55mooredbuoysareusedtovalidatethembyusingthe30minand25kmcollocationwindow.Furthermore,theobjectivelyanalyzedair-seaheatfluxes(OAFlux)productsandtheNationalCentersforEnvironmentalPrediction-NationalCenterforAtmosphericResearchreanalysis2(NCEP2)productsarealsousedforglobalcomparisons.ThemeanbiasesofsensibleandlatentheatfluxesbetweenWindSatfluxresultsandbuoyfluxdataare–0.39and–8.09W/m~2,respectively.Inaddition,therootmean-square(RMS)errorsofthesensibleandlatentheatfluxesbetweenthemare5.53and24.69W/m~2,respectively.TheRMSerrorsofsensibleandlatentheatfluxesareobservedtograduallyincreasewithanincreasingbuoywindspeed.Thedifferenceshowsdifferentcharacteristicswithanincreasingseasurfacetemperature,airhumidity,andairtemperature.ThezonalaveragelatentfluxeshavesomehighregionswhicharemainlylocatedinthetradewindzoneswherestrongwindscarrydryairinJanuary,andthemaximumvaluecentersarefoundintheeasternwatersofJapanandontheUSeastcoast.Overall,theseasonalvariabilityispronouncedintheIndianOcean,thePacificOcean,andtheAtlanticOcean.Thethreesensibleandlatentheatfluxeshavesimilarlatitudinaldependencies;however,somedifferencesarefoundinsomelocalregions.

简介：孔隙结构特征及类型划分对低渗透储层勘探开发至关重要,基于多重分形理论与核磁共振实验,对东营凹陷南坡沙河街组沙四段（ES4）复杂低渗透砂岩进行孔隙结构研究。首先,根据岩心物性、铸体薄片、压汞等资料所反映的孔隙结构参数差异,将研究区的岩石孔隙结构类型划分了3大类5小类;然后,针对不同类型岩石的核磁共振T2谱进行插值并计算其对数坐标下的一维、三维分形维数以及多重分形谱,并提取多重分形参数奇异性强度α、分布稠密度f（a）,结果显示孔隙结构类型不同,盒维数尤其是多重分形参数值差异明显,孔隙结构好,其a、f（a）偏向高值,以此划分孔隙结构类型与压汞、薄片分析结果基本一致;最后,将该方法应用到核磁共振测井剖面上,应用效果较好,表明多重分形是核磁共振T2谱的一种属性,利用核磁测井T2谱多重分形特征及参数能够连续较好地评价低渗透砂岩孔隙结构类型与预测有效储层。

简介：当时，本地联合不稳定性将发生吸收边界状况和地波浪方程的数字计划允许精力自发地进入计算领域。也就是说，二个计划支持普通波浪解决方案，组速度指了进计算域。消除联合不稳定性的本地人的钥匙是避免如此的波浪答案。为块团在2D波导的P-SV波浪运动的有限元素模拟，为高顺序的稳定的实现的一条途径多播送的公式被提供。与一个一致矩形的网孔，它被证明并且验证那高周波的本地联合不稳定性能被设置等于或比\大的元素尺寸的比率消除(\sqrt2\)乘到S波浪速度的P波浪速度的比率。这些结果能为发另外的吸收边界条件导致的不稳定性问题是珍贵的。

简介：本文以“社交媒体多层次信息流”为概念框架，分析了四川九寨沟7．0级地震发生后，个人、当地的组织、宏观层面的主流媒体使用社交媒体所发挥的作用。通过对微博的数据进行挖掘分析，总结出地震灾害发生后社交媒体所具有的5项功能：人际之间的交流，地方政府、本土组织以及当地媒体的传播渠道，大众传媒信息发布的渠道，信息的收集和分享，微观、中观以及宏观各主体间沟通的渠道。在强震发生后社交媒体有巨大的传播潜力，本文的研究成果对未来大震发生后如何利用社交媒体来应对灾害有一定的借鉴意义。

简介：《海洋环境保护法》第89条第2款本身并非关于诉讼的直接规定,该款规定的内容也不符合民事公益诉讼的内涵特征,将该款解释为关于海洋环境民事公益诉讼的规定不利于我国立法内部的横向协调。我国司法实践总体上也不认可《海洋环境保护法》第89条第2款规定的内容属于海洋环境民事公益诉讼。《海洋环境保护法》第89条第2款应是关于损害赔偿请求权的特别规定,不是我国海洋环境民事公益诉讼的法律依据,相应的法律依据应是《环境保护法》第58条、《民事诉讼法》第55条以及相关司法解释。