简介:TheZ-backlighterlaserfacilityprimarilyconsistsoftwohighenergy,high-powerlasersystems.Z-Beamletlaser(ZBL)(Ramboetal.,Appl.Opt.44,2421(2005))isamulti-kJ-class,nanosecondlaseroperatingat1054nmwhichisfrequencydoubledto527nminordertoprovidex-raybacklightingofhighenergydensityeventsontheZ-machine.Z-Petawatt(ZPW)(Schwarzetal.,J.Phys.:Conf.Ser.112,032020(2008))isapetawatt-classsystemoperatingat1054nmdeliveringupto500Jin500fsforbacklightingandvariousshort-pulselaserexperiments(seealsoFigure10forafacilityoverview).Withthedevelopmentofthemagnetizedlinerinertialfusion(MagLIF)conceptontheZ-machine,theprimarybacklightingmissionsofZBLandZPWhavebeenadjustedaccordingly.Asaresult,wehavefocusedourrecenteffortsonincreasingtheoutputenergyofZBLfrom2to4kJat527nmbymodifyingthefiberfrontendtonowincludeextrabandwidth(forstimulatedBrillouinscatteringsuppression).TheMagLIFconceptrequiresawell-defined/behavedbeamforinteractionwiththepressurizedfuel.HencewehavemadegreateffortstoimplementanadaptiveopticssystemonZBLandhaveexploredtheuseofphaseplates.WearealsoexploringconceptstouseZPWasabacklighterforZBLdrivenMagLIFexperiments.Alternatively,ZPWcouldbeusedasanadditionalfusionfuelpre-heaterorasatemporallyflexiblehighenergypre-pulse.AlloftheseconceptsrequiretheabilitytooperatetheZPWinananosecondlong-pulsemode,inwhichthebeamcanco-propagatewithZBL.Someoftheproposedmodificationsarecompleteandmostofthemarewellontheirway.
简介:Icewatercontent(IWC)playsimportantrolesinweatherandclimatechange.DeterminingtheIWCsofcirruscloudswithmillimeter-wavelengthradarcanbeproblematicduetoinfluencesoficeparticlerotationontheirbackscatteringcrosssections.Wehereintroducemodelstodescribetheradiationpatternsofsixnonsphericalparticlesofspecificsizes.SimulationsusingHFSSsoftwarewereappliedtodescribethedifferencesresultingfromdifferentorientationsandequivalentspheres.Adoubleexponentialfunctionwasusedforfittingtodescribetherelationshipbetweentheparticles’maximumsizesandbackscatteringcrosssections.Thebackscatteringcrosssectionsofnonsphericaliceparticleswerecomputedbythemethodofmoment,andthoseoftheequivalentsphericalparticleswerecomputedbyLorenz-Mietheoryforthreedifferentorientations:fixed,horizontal,andrandom.AssumingthatamixtureofnonsphericaliceparticlesfollowstheB-Hmixingmodel,thesizedistributionofcirrusparticlesobeystheexponentialdistributionmeasuredbyNASAin2007.BycomputingtheIWCsofcirrusclouds,whichfollowstheabovementionedB-Hmodelandexponentialdistribution,theradarreflectivityfactorsofnonsphericaliceparticlesandequivalentspheresatthreedifferentorientationscanbecomputed.Subsequently,theIWCresultscanbeacquiredbyinputtingtheradarreflectivityvariablesintothewell-knownIWC-Zformula.TheanalysisdescribedheredemonstratesthatwhenusingtheradarreflectivityZ,theorientationmustbeconsideredinordertodeterminetheIWC.Usingequivalentspheretheory,thederivedIWCsunderestimatetheactualIWCs.Theseresultsareimportantforaccuratelyretrievingthemicrophysicalparametersofcirrusclouds.
简介:摘要目的比较双球囊与单球囊椎体后凸成形术治疗骨质疏松性脊柱压缩骨折的临床效果。方法选择2013年9月-2015年12月期间在我院接受椎体后凸成形术治疗的骨质疏松性脊柱压缩骨折患者50例作为研究对象,根据术式不同划入观察组和对照组,观察组25例,对照组25例,分别接受单球囊椎体后凸成形术和双球囊椎体后凸成形术治疗,比较两组患者的手术成功率、球囊压力、VSA评分。结果全部患者手术操作成功,无力并发症,球囊最大压力150-300psi,平均229.8±80.4psi,单椎体骨水泥填充量3.4-6.2ml,平均5.6ml,术后96h开始疼痛逐渐缓解,术后VSA评分2.6±1.4分,前后差异显著,随访12个月无疼痛加重病例,组间差异无统计学意义,P>0.05。结论单球囊椎体后凸成形术治疗骨质疏松性脊柱压缩骨折临床效果和双球囊与单球囊椎体后凸成形术相比差异无统计学意义,但是手术成本更低。