简介：Inthispaper,responsesofanewdual-inductionresistivitylogging-while-drilling（LWD）toolin3Dinhomogeneousformationmodelsaresimulatedbythevectorfiniteelementmethod（VFEM）,theinfluencesoftheborehole,invadedzone,surroundingstrata,andtooleccentricityareanalyzed,andcalibrationloopparametersandcalibrationcoefficientsoftheLWDtoolarediscussed.TheresultsshowthatthetoolhasagreaterdepthofinvestigationthanthatoftheexistingelectromagneticpropagationLWDtoolsandismoresensitivetoazimuthalconductivity.Bothdeepandmediuminductionresponseshavelinearrelationshipswiththeformationconductivity,consideringoptimalcalibrationloopparametersandcalibrationcoefficients.Duetothedifferentdepthsofinvestigationandresolution,deepinductionandmediuminductionareaffecteddifferentlybytheformationmodelparameters,therebyhavingdifferentcorrectionfactors.Thesimulationresultscanprovidetheoreticalreferencesfortheresearchandinterpretationofthedual-inductionresistivityLWDtools.

简介：Theresponseofsedimentdischargeratetothefollowingfourecohydrologicalfactors:temperature,rainfall,evapotranspiration(ET),andstreamflowwasevaluatedbyconductingwaveletanalysisonLuergousmallcatchmentdatarangingfrom1982to2000.Forsedimentdischargerate,therewasanoveralltrendofreductionthatincludedaperiodicoscillationof6to7yearspercycle.Rainfallalsohadanoveralltrendofreductionthatincludedtwoperiodicoscillationsof7yearspercycleand2yearspercycle,respectively.Streamflowhadthesametrendasrainfallbuthadoneperiodicoscillationof6to7yearspercycle.Incontrastwithrainfallandstreamflow,thetrendsfortemperatureandETeachshowedanoverallincreasingtendency,andbothhadthesametwoperiodicoscillationsof6to7yearspercycleand4yearspercycle,respectively.Thesedimentdischargeratehadsignificantrelationshipswiththefourecohydrologicalfactors,withstreamflowandrainfallhavingpositivecorrelations,whileETandtemperaturehadnegativecorrelations.ThecorrelationbetweenETandsedimentdischargeratebecamestrongerwhenETwascomparedtothesedimentdischargerateofthefollowingyear.Therelationshipbetweensedimentdischargerateandthefourecohydrologicalfactorswasfurtherexpressedbythemulti-linearregressionmodelthatwasconstructed,whichmakessedimentdischargerateafunctionofstreamflow,rainfall,ET,andtemperature.

简介：为勘探地震学的一个重要研究话题是提供一个快精确速度模型从预先叠深度移植。瞄准如此的一个问题，我们建议二次的精确概括了非线性的全球优化迁居速度倒置。首先，我们丢弃在剩余深度和剩余速度之间有一种线性关系并且求婚的假设有使从每次重复的速度模型能尽可能快速走近真正的模特儿的二次的精确的一个速度模型修正方程。第二，我们使用概括非线性的倒置得到全球最佳的速度不安模型到所有踪迹。这个方法能帮助集中速度并且能也减少在倒置期间掉进本地最小的概率。合成数据和Marmousi数据例子证明我们的方法有更高的精确并且需要仅仅一些重复并且因而在复杂区域提高迁居速度分析(MVA)的有实行可能和精确性。

简介：Climatechangecharacterizedbyincreasingtemperatureisabletoaffectprecipitationregimeandthussurfacehydrology.However,themannerinwhichriversedimentloadsrespondtoclimatechangeisnotwellunderstood,andrelatedassessmentregardingtheeffectofclimatechangeonsedimentloadsislacking.Wepresentaquantitativeestimateofchangesinsedimentloads(from1.5Gtyr~(-1)pre-1990to0.6Gtyr~(-1)from1991-2007)inresponsetoclimatechangeineightlargeChineserivers.Overthepastdecades,precipitationchangecoupledwithrisingtemperatureshasplayedasignificantroleininfluencingthesedimentdeliverydynamics,althoughhumanactivities,suchasreservoirconstruction,waterdiversion,sandminingandlandcoverchange,arestillthepredominantforces.Lowerprecipitationcoupledwithrisingtemperatureshassignificantlyreducedsedimentloadsdeliveredintotheseainsemi-aridclimates(4-61%).Incontrast,increasinglywarmerandwetterclimatesinsubtropicalzoneshasyieldedmoresediment(0.4-11%),althoughtheincreasewasoffsetbyhumanimpact.Ourresultsindicatethat,comparedwithmechanicalretentionbyreservoirs,waterreductioncausedbyclimatechangeorhumanwithdrawalshascontributedmoresedimentreductionfortheriverswithabundantsedimentsupplybutlimitedtransportcapacity(e.g.,theHuanghe).Furthermore,ourresultsindicatethatevery1%changeinprecipitationhasresultedina1.3%changeinwaterdischargeanda2%changeinsedimentloads.Inaddition,every1%changeinwaterdischargecausedbyprecipitationhasledtoa1.6%changeinsedimentloads,butthesamepercentageofwaterdischargechangecausedlargelybyhumanswouldonlyresultina0.9%changeinsedimentloads.Thesefigurescanbeusedasaguidelineforevaluatingtheresponsesofsedimentloadstoclimatechangeinsimilarclimatezonesbecausefutureglobalwarmingwillcausedramaticchangesinwaterandsedimentinriverbasinsworldwideatratespreviouslyunseen.

简介：训练策略的一条河的选择为更低的黄河(LYR)是极其重要的。当前，宽河的训练策略在训练LYR适用。然而，在在黄河盆的水文学过程的显著变化，以及从在黄河盆的社会经济的开发的立即的压力，使如果有可能性改变从到狭窄河的训练的宽河的训练训练策略的河，考虑必要。这研究调查通过数字模拟在LYR上训练策略的不同的河的影响。一一个维(1-D)模型被用来为未来模仿河的过程50年并且一三维(3-D)模型被使用学习典型洪水。学习集中了于河形态学，结果看那在两水分泌物的在场减少趋势和沉积负担是否坚持，在LYR的免职率将进一步减少不管什么策略被使用。特别，狭窄河的训练能达到目的与宽河的训练相比在LYR增加沉积运输能力。如果到来的水和沉积负担恢复到最后世纪的吝啬的水平，主要隧道收缩不管多么不可避免地由于沉积发生为宽河、狭窄河训练。最重要地，这研究证明狭窄河的训练在整个LYR上减少免职数量，但是它几乎不在减轻推迟的河的发展提供很少帮助。相反，狭窄河的训练能在河模式从高度漫步到蜿蜒地流变化的过渡活动范围引起沉积，进一步的变得更坏在那里的驼峰免职。因为关于在在可行工程的黄河盆，和缺乏的水文学过程的未来变化的无常，测量在LYR减轻推迟的河和驼峰免职问题，小心应该在为LYR训练策略的河里关于变化被行使。