简介:ThedistributionofmonthlymeanerrorofNMCmodelforecastsanditsseasonalvariationareinvesti-gated.Theratioofmonthlymeanerrortostandarddeviationisusedheretofindoutthattheregionwhereacorrectionofsystematicerrorisneededandappropriateismainlyinlowlatitudes.Theimprovement,afterthemodel’sverticalresolutionandsomephysicalparameterswerechangedfromApril1985,isinvestigated,andtheNMCoperationalmodelforecastshavealsocomparedwiththoseofECMWF.
简介:摘要:自古以来,人工开凿水道一直是农业灌溉的关键环节。伴随我国农业的迅速发展,以灌溉为目的的人工渠道形式也呈现出梯形、U形等多种形式。其中,通过大量的实践活动,得出的理论基础是:U型渠道与其他渠道相比,具有耐久、方便等特点,在中小型农田灌溉中能起到比较广泛的作用。U形沟道在农业灌溉的具体应用中,需要综合考虑沟道的地形、地势、海拔、温度等因素,在荒漠、戈壁等干旱地区,实际设计沟道时,需适当改变沟道外倾角,以减少水分蒸发,提高水资源利用率,节约用水;在高纬度地区、高原地区等低温条件下,沟道内衬混凝土时,需适当增加U形沟道外倾角,增加其抗寒能力和稳定性,防止沟道在极端气候条件下遭到破坏。
简介:ThispaperpresentsthefirstspecificstudyoftheTh-andU-bearingminerals,whichwererecentlyfoundintheSEMediterraneanmarginofSpain(ElHoyazoarea,Almeriaprovince).ThesemineralsareREEphosphates(mainlymonazite)whichoccurasamoeboidal-to-elongateinclusions,fromaround10120μmto120μm,hostedinsinglegarnetcrystalsfromdacitelavasandmetamorphicrocksfromtheElHoyazoVolcanicComplex.ThandUcontentsarehigherthan1wt%,with3.04to5.62wt%forTh02,and0.7to1.75wt%forUO2.Bothelementsarealsofoundinxenotime(ThO2:0.24,UO2:0.27wt%).Giventhattheerosionofthevolcanicsourcerockshasgenerateda“placer-type”depositofmonazitesandsandthatgarnets(maincarriersofmonazite)arebeingcommercialised,anenvironmentalmonitoringandmanagementplanshouldbeurgentlyexecutedinthearea.
简介:MarbleisassociatedwithultrahighpressureeclogiteintheDabieMountains.EastChina.U-Pbisotopedataforthemarbledefinea238U-206Pbisochronageof435±45awithaninitial206Pb/204Pbvalueof18.075±0.006,Theageof-435MaisinterpretedtorepresentthetimeoflimestonediagensisratherthanthetimeofmetarmorphicresettingaccompaniedbytheformationoftheultrahighpressureeclogitesatTriassic.ThepaleontologicandstratigraphicstudiesalsofavoralocalexcursioninthecarbonisotopiccompositionofthelatestordovicianwaterwithinasedimentarybasinbetweentheSino-KoreanandYangtzecratos.Becasusethelatestordovicianlimestonewasinvolvedintheeclogiteformation,thecontinentalcollisionbetweentheYangtzeandSino-KoreanPlateswouldpostdateordovican.
简介:Calculations,accordingtosomeopen-systemmodels,pointoutthatwhileastatisticallysignificantdiscrepancybetweentheresultsoftwoU-seriesmethods,^230Th/^234Uand^227Th/^220Th(or^231Pa/^235U),attestsarelativelyrecentandimportanturaniummigration,concordantdatescannotguaranteecloses-systembehaviorofsample.Theresultsof20fossilbonesfrom10Chinesesites,19ofwhicharedeterminedbytwoU-seriesmethods,aregiven,Judgingfromindependentagecontrols,8outofthe11concordantagesetsareunacceptable,Theresultsinthispapersuggestthaturaniummaycycleintooroutoffossilbones,suchgeochemicaleventsmaytakeplaceatanytimeandnoknownpreservingconditionmaysecurelyprotectthemfrombeingaffected.Soforthesitewwehavestudied,theU-seriesdatingoffossilbonesisoflimitedreliability.
简介:GlobalabruptclimatechangefromMarinoansnowballEarthtogreenhouseEarth,recordedascapcar-bonateoverlainondiamictite,hadshedthefirstlightonCambrianbio-radiation.Themostdocumentedcapcar-bonatesectionsaretypicalwithcomprehensiveδ13Cneg-ativevaluesandubiquitoussedimentarystructures,suchastepee-like,sheet-cracketc.,whichareassociatedwithsuccessiveglacialeustaticvariationcausedbyisostaticreboundinshallow-waterfacies.Herewereportadeep-waterbasinalcapcarbonatesectionwithstrongnegativeδ13CvaluesinthesouthernmarginoftheQinlingOrogen,Heyu,ChengkouCounty,ChongqinginChina,whichconsistsofmassivedolostonewithabundantcarbonaceouslaminae.However,itlacksthesedimentarystructureasmentionedaboveandisoverlainbythin-beddedsiliciousshalesandcherts.AK-bentonitebedwasdiscoveredwithinthebaseofcapcarbonates,about0.7mabovethetopoftheMarinoandiamictite.Magmaticzirconsthatweresep-aratedfromtheK-bentonitebedyieldaSIMSconcordiaU-Pbageof634.14-1.9Ma(lσ,MSWDcE=0.31,ProbabilityCE=1.000,n-=20).TheageisingoodagreementwithpreviouslyreportedTIMSU-PbagesfortheterminationofMarinoanglaciationandprovidesageochronologicalconstraintfortheEdiacaransuccessionsintheQinlingOrogen.
简介:摘要: 考虑钢筋混凝土 U 型槽结构产生裂缝的因素,结合武汉市东湖国家自主创新示范区有轨电车 T2 试验线 U 型槽结构的实际情况,分析 U 型槽裂缝产生的原因,并提出控制措施。
简介:【摘要】通过驮英水库及灌区工程总干渠标段工程实例,介绍了“U”型渡槽15m跨槽身混凝土模板支撑体系布局及计算过程,对类似工程施工具有参考价值。
简介:在结晶化以后沿着Yangtzecraton和他们的变形历史的西方边缘澄清变形侵入的关系,石油化学并且踪迹元素geochemical人物,标明日期的锆石虾U-Pb,和化学药品从在Kangding的Neoproterozoic变形侵入的共存的角闪石和斜长石的作文(),四川()省,和Yuanmou(),云南()省,被学习。与以前的出版数据结合了,在Yangtzecraton的西方边缘的Kangding花岗石的plutons和Yuanmou建筑群通常在一样的句号形成了,这被显示。在700妈的变形事件广泛地存在,至少在四川从Kangding区域盖住到Eshan()在中央云南的区域。而且,角闪岩外形可以代表山峰地区性的变形状况。
简介:FollowingtherecommendationoftheInternationalCommissiononStratigraphy(16votesYes[94%],1abstention,2votesnotreceived),theGlobalboundaryStratotypeSectionandPoint(GSSP)forthebaseoftheTuronianStageoftheCretaceousSystemisdefinedasthebaseofbed86oftheBridgeCreekLimestoneMemberoftheGreenhornLimestoneFormationatthewesternendoftheDenverandRioGrandeRailroadcutnearthenorthboundaryofthePuebloReservoirStateParkRecreationArea,westofPueblo,Colorado,USA.ThisGSSPhorizonisalsoexposedandprotectedintheadjacentstaterecreationarea.ItcoincideswiththefirstoccurrenceoftheammoniteWatinocerasdevonense,isinthemiddleofaglobalpositiveexcursioninCarbon-13isotopes,andisbracketedbywidespreadbentonitesthathaveyieldedagesof93to93.5Ma.