简介:摘要:能源、资源与环境问题是影响人类经济可持续发展和社会和谐的重要因素,化石能源的巨大消耗使得在全球范围内出现能源危机。建设节约型社会,减少热损失、能源浪费和提高热能利用率是整体发展趋势。气凝胶独特的三维纳米孔洞结构赋予其极低的导热系数,被认为是一种“超级绝热材料”广泛应用于航空航天、城市热力管网、石油化工管道、工业窑炉等领域。但气凝胶脆弱的纳米多孔结构导致其自身的强度极低,易碎,难以直接应用于隔热防护领域。因此,本文针对气凝胶材料的增强进行了多角度、深层次的分析与研究,希望可以推动气凝胶材料性能的提升,发挥气凝胶材料在能源节约方面的优势,为国民经济作出贡献。
简介:目的比较3D腹腔镜与2D腹腔镜辅助远端胃癌根治术中的临床应用,探讨3D腹腔镜手段的可行性和安全性。方法选取2015年1月至2017年6月确诊为进展期胃癌并分别接受3D腹腔镜(3D组)和2D腹腔镜(2D组)D2辅助远端胃癌根治术的患者各34例,采用SPSS18.0统计软件进行统计学处理,术中及术后恢复指标及术后生活质量评分等计量资料以(±s)表示,数据比较采用独立t检验;术后并发症及术后生存率等比较采用χ2检验或Fisher精确检验,以P<0.05为差异有统计学意义。结果与2D组比较,术后3D组出血量明显较少,淋巴结清扫数目明显更多,差异具有统计学意义(P<0.05);两组肛门排气时间、进流食时间、近切缘及远切缘距离、术后住院时间、术后并发症发生率、术后6个月生活质量评分以及1年、2年生存率等比较,差异均无统计学意义(均P>0.05)。结论相比2D腹腔镜手术,3D腹腔镜辅助下实施D2根治术可有效减少术中出血量,提高淋巴结清扫数目,方便医生操作使用,且不增加术后并发症或降低生存质量和生存率,值得在临床中推广使用。
简介:The2Dplanegasflowunderheating(withnonentityboundarycondition)hasbeendiscussedbytheanalyticalapproachinthispaper.Theapproximateanalyticalsolutionshavebeenobtainedfortheflowpassingvariouskindsofheatsources.Solutionsdemonstratethethermaldisplacementphenomenaarestronglydependontheheatingintensity.
简介:Cavitationisoneofthetroublesomeproblemsinrocketturbopumps,andsincemostofhigh-efficiencyrocketpropellantsarecryogenicfluids,socalled'thermodynamiceffect'becomesmoreevidentthaninwater.Inthepresentstudy.numericalandexperimentalstudyofliquidnitrogencavitationin2DLavalnozzlewascarriedout,sothattheinfluenceofthermodynamiceffectwasexamined.Itwasrevealedthattemperatureandcavitationhavestronginter-relationshipwitheachotherinthermo-sensitivecryogenicfluids.
简介:摘要悬吊肝脏,于横结肠中部大网膜附着处向左切开网膜,分离切断胃网膜左血管,至胃短血管第二支,清扫第4sb组淋巴结;分离横结肠系膜前叶右侧部分至大网膜完全从结肠离断,显露胰头、十二指肠球部,离断胃网膜右动静脉,清扫第4d、6组淋巴结;从右向左,从下向上剥离胰腺被膜;显露胰腺上缘,分离肝总动脉表面,清扫第8a、12a组淋巴结;分离切断胃左动静脉,沿脾动脉向左分离至胃后血管为止,清扫第7、9、11p组淋巴结;解剖胃小弯区域,离断肝胃韧带,分离胃右动静脉并清扫肝十二指肠韧带的第5、12a组淋巴结;暴露右侧膈肌角,游离至食管裂孔,清扫第1、3组淋巴结。胃肠重建采用直线切割闭合器行BillrothⅡ式吻合,共同开口以倒刺线缝闭。
简介:DevelopedatColoradoStateUniversity,CASC2D-SEDisaphysically-basedmodelsimulatingthehydrologicresponseofawatershedtoadistributedrainfallfield.Thetime-dependentprocessesinclude:precipitation,interception,infiltration,surfacerunoffandchannelrouting,uplanderosion,transportandsedimentation.CASC2D-SEDisappliedtoGoodwinCreek,Mississippi.Thewatershedcovers21km2andhasbeenextensivelymonitoredbothattheoutletandatseveralinternallocationsbytheARS-NSLatOxford,MS.Themodelhasbeencalibratedandvalidatedusingrainfalldatafrom16meteorologicalstations,6streamgaugingstationsand6sedimentgaugingstations.Sedimenterosion/depositionratesbysizefractionarepredictedbothinspaceandtime.Geovisualization,apowerfuldataexplorationtechniquebasedonGIStechnology,isusedtoanalyzeanddisplaythedynamicoutputtimeseriesgeneratedbytheCASC2D-SEDmodel.
简介:Thispaperproposesanewtechniquethatisusedtoembeddepthmapsintocorresponding2-dimensional(2D)images.Sincea2Dimageanditsdepthmapareintegratedintoonetypeofimageformat,theycanbetreatedasiftheywereone2Dimage.Thereby,itcanreducetheamountofdatain3Dimagesbyhalfandsimplifytheprocessesforsendingthemthroughnetworksbecausethesynchronizationbetweenimagesfortheleftandrighteyesbecomesunnecessary.Weembeddepthmapsinthequantizeddiscretecosinetransform(DCT)dataof2Dimages.Thekeytothistechniqueiswhetherthedepthmapscouldbeembeddedinto2Dimageswithoutperceivablydeterioratingtheirquality.Wetrytoreducetheirdeteriorationbycompressingthedepthmapdatabyusingthedifferencesfromthenextpixeltotheleft.Weassumethatthereisonlyonenon-zeropixelatmostononehorizontallineintheDCTblockbecausethedepthmapvalueschangeabruptly.Weconductanexperimenttoevaluatethequalityofthe2Dimagesembeddedwithdepthmapsandfindthatsatisfactoryqualitycouldbeachieved.
简介:Thehumanvisionsystemcanreconstructa3Dobjecteasilyfromsingle2Dlinedrawingsevenifthehiddenlinesoftheobjectareinvisible.Now,therearemanymethodshaveemulatedthisability,butwhenthehiddenlinesoftheobjectareinvisible,thesemethodscannotreconstructacomplete3Dobject.Therefore,weputforwardanewalgorithmtosettlethishardproblem.Ourapproachconsistsoftwosteps:(1)infertheinvisibleverticesandedgestocompletethelinedrawing,(2)proposeavertex-basedoptimizationmethodtoreconstructa3Dobject.
简介:摘要随着智能终端设备不断增加和网络流量的持续上升,现有的通信技术已无法满足未来通信要求。终端直通(Device-to-Device,D2D)通信作为第五代移动通信网(5G)的关键技术能有效缓解数据压力,提高频谱利用率。本文介绍了D2D的优点,详细分析了D2D通信中的关键技术环节,展望了D2D未来发展重点及主要方向。
简介:为了改善海藻酸钠固定化酶微球的扩散性与酶活稳定性,以纳米二氧化钛修饰海藻酸为固定化酶载体,Ca2+,Ce3+,Ni2+,Cu2+和Fe3+为杂化凝胶的阳离子交联剂,木瓜蛋白酶为模型酶,制备固定化酶微球.通过UV-Vis光谱检测酶活,考察了5种交联剂对固定化酶的动力学和稳定性的影响,结果表明:当Cu2+为交联剂时,固定化酶具有最高的亲和性、最低的米氏常数(Km=11.0mg/mL)和最高的稳定性.研究了TiO2与木瓜蛋白酶的质量比对固定化酶稳定性以及酶蛋白泄漏的影响,结果显示纳米二氧化钛与木瓜蛋白酶的质量比为10∶1时,制备的固定化酶微球性能最好,因为二氧化钛能有效阻止固定化酶的泄漏.通过离子胶凝制备Cu/海藻酸/TiO2杂化凝胶可获得较好的扩散能力和酶活稳定性.
简介:Anewmethodforfabricatingorderedporoussiliconisreported.Atwo-dimensionalsilicananospherearrayisusedasatemplatewithahydrofluoricacid-hydrogenperoxidesolutionforetchingthenanospheres.Theinitialdiameteranddistributionoftheholesintheresultingporoussiliconlayeraredeterminedbythesizeanddistributionofthesilicananospheres.Thecorrosiontimecanbeusedtocontrolthedepthsoftheholes.ItisfoundthatthepresenceofaSiO_2layer,formedbytheoxidationoftheroughinternalsurfaceofthehole,istheprimaryreasonallowingthecorrosiontoproceed.Ultravioletreflectionandthermalconductivitymeasurementsshowthatthediameteranddistributionoftheholeshaveagreatinfluenceonpropertiesoftheporoussilicon.