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:一、地震基本参数表1 地震基本参数表发震时间年月日时分秒震 中 位 置微 观宏 观东经北纬东经北纬参考地名震级(MD)震源深度(Km)震中烈度 地震类型 199203030602228118°10′24°06′118°06′24°12′漳浦海外(厦门南)48Ⅴ孤立型 表1中宏观震中是根据陆地上勾划的等震线推测的,在微观震中的北西20公里左右。二、地震烈度分布本次地震的波及面很广,闽东南沿海地区均明显有感,调查在Ⅴ、Ⅳ度两个区内进行。由于地震影响场只有一小半在陆地上,勾勒出的是Ⅴ、Ⅳ度两条等震线的半椭圆弧线(见图14-1)。图14-1 1992年3月3日漳浦海外地震等震线图Ⅴ度区:震中位于海上
简介:<正>所谓3S技术即GPS、GIS、RS技术。GPS(全球定位系统)是英文缩写词NAVSTAR/GPS(NAVigationSystemTimeAndRanging/GlobalPositioningSystem)的简称。全称应为“测时测距导航系统/全球定位系统”。GPS是由美国研制,并投入实际应用的最新卫星定位系统。其主要目的是为飞机和船舶导航定位。也可以用于其它多种目的。GPS技术已在航空、航天、航海、军事、地质、石油、勘探、交通、测绘等领域得到广泛的应用。美国于1993年6月26日已将GPS21颗卫星和3颗备用卫星全部发射入轨。