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500 个结果
  • 简介:AnovelmethodformodelingcellularmaterialsisproposedbasedonMATLABimageprocessingandsynchrotronX-raycomputedtomographyscanningtoobtainanaccuratecalculationresultofaluminumfoambasedonfiniteelementmodel.Themaximumentropyalgorithmisemployedtoobtainthebinarizationimage,andthemedianfilteringalgorithmisusedtoreducethenoiseafterbinarization.Theexternalcontourandinternalporesboundaryisextractedbythe"edge"functioninMATLAB,andthegeometricalmodelisreconstructed.Atwo-stepmeshalgorithmisadoptedtomeshthereconstructedgeometricalmodel.Accordingly,thefiniteelementmodelofaluminumfoamisestablishedbytheproposedmethodbasedonreconstructiongeometricalmodel.Thecompressionbehaviorofaluminumfoamisobtainedat25℃,100℃,200℃byABAQUS,andgoodagreementswithexperimentsareachievedbyapplyingthepresentreconstructionalgorithmandmodelingmethod.

  • 标签: 泡沫铝 有限元建模 材料响应 重建方法 三维几何 MATLAB
  • 简介:在这份报纸,用水泡功能,我们构造一个长方元素解决第四份订单在三种尺寸的椭圆形的单个不安问题。我们证明nonconformingC0长方元素关于不安参数一致地在精力标准收敛。[从作者抽象]

  • 标签: 奇异摄动问题 非协调元 一致收敛 椭圆 四阶 3-D
  • 简介:PD(X3?)相互作用潜力用CCSD(T)理论和基础集合被构造,aug-cc-pV5Z。用这个潜力,分光镜的参数是精确地坚定的。礼品,De,Re,e,ee,e,并且具有3.05699eV,3.16175eV,0.14239nm,1701.558厘米?1,23.6583厘米?1,0.08599厘米?1,和4.3963厘米?1,分别地它几乎完美地符合大小。当时,26个震动的状态的一个总数被预言J=0由解决光线的Schr?原子运动的dinger方程。完全的震动的层次,古典拐弯处点,起始的旋转和离心的失真常数什么时候J=0第一次被报导,它有利地同意实验。全部、各种各样的部分波浪的生气的节在1.0魄为在个地面状态P和D原子之间的有弹性的影响被计算吗??

  • 标签: 弹性碰撞 基态原子 低温度 横截面形状 大陆科学钻探 相互作用势
  • 简介:设α是正实数,[α0;α1,α2。…]是α的简单连分数;d是非平方整数,d1、d2是适合d1d2=d,1≤d1<d2,gcd(d1,d2)=1的正整数,本文证明了:当且仅当α=(d2/d1)(1/2)时,α=[α0α1,…αn-1,2α0],其中α0>0,αi=αn-1(i=1…,α-1).

  • 标签: 简单连分数 正整数 渐近分数 当且仅当 定理 引理
  • 简介:Inthispaper,westudytheCauchyproblemforthe3DgeneralizedNavier-Stokes-Boussinesqequationswithfractionaldiffusion:{ut+(u·▽)u+v∧2αu=-▽p+θe(3),e3=(0,0,1)T,θt+(u·▽)θ=0,Dicu=0.Withthehelpofthesmoothingeffectofthefractionaldiffusionoperatorandalogarithmicestimate,weprovetheglobalwell-posednessforthissystemwithα≥5/4.Moreover,theuniquenessandcontinuityofthesolutionwithweakerinitialdataisbasedonFourierlocalizationtechnique.Ourresultsextendonesonthe3DNavier-Stokesequationswithfractionaldiffusion.

  • 标签: BOUSSINESQ方程 整体适定性 广义 三维 分数阶 柯西问题
  • 简介:Theimportantintermediateforsynthesesofvariousanti-HIVnucleosideanalogues,methyl2,3-dideoxy-3-fluoro-6-O-(p-methylbenzoyl)-a-D-ribofuranoside,wassynthesizedstartingfrom2-deoxy-D-ribosein5stepswithanoverallyieldof24%.Thisstrategycanbealsousedforsynthesizingotheranalogueswithvarioussubstitutionsat3-Cposition.

  • 标签: NEW method STEREOSELECTIVE synthesis 2 3-dideoxy-3-substituted-D-ribofuranoside
  • 简介:从地下的管子的漏能导致被破坏并且引起损坏到邻近的基础结构的基础。包围漏的区域的土壤粒子能从由漏的液体的土壤矩阵被动员,代替,并且甚至洗了,产生虚空或洞。用acoupled的维的模拟分离元素方法和格子Boltzmann方法(DEMLBM)被用来调查一个土壤床题目的行为到局部地注射的液体,它在一根管子中代表一条漏缝。内部粒子的表面精力的各种各样的价值也被采用为连贯的粒子的机械效果建模。结果建议内部粒子的表面精力极大地关于漏的液体影响床反应,包括开始洞,洞形状和它的进化率的过量压力。

  • 标签: 土壤颗粒 注射液 格子BOLTZMANN方法 行为 二维 管道泄漏
  • 简介:Antibacterialpoly(D,L-lactide)(PDLLA)fibrousmembranesweredevelopedviaelectrospinning,followedbysurfacemodificationwhichinvolvedplasmapretreatment,UV-inducedgraftcopolymerizationof4-vinylpyridine(4VP)andquaternizationofthegraftedpyridinegroupswithhexylbromide.ThesuccessofmodificationwithquatemizedpyridiniumgroupsonthePDLLAfibrousmembraneswasascertainedbyX-rayphotoelectronspectroscopy(XPS).TheantibacterialactivitiesofthesemembraneswereassessedagainstGram-positiveStaphylococcusaureus(S.aureus)andGram-negativeEscherichiacoli(E.coli).ThePDLLAfibrousmembranesmodifiedwithquaternizedpyridiniumgroupsshowedantibacterialefficiencyagainstbothbacteriaashighas99.999%.Theresultsdemonstratedthattheantibacterialactivitywasbasedontheinteractionofthepositivechargeofpyridiniumgroupandnegativelychargedcellmembraneofbacteria,resultinginlossofmembranepermeabilityandcellleakage.

  • 标签: 等离子体表面改性 聚乳酸纤维 吡啶季铵盐 抗菌活性 纤维膜 金黄色葡萄球菌
  • 简介:Wakestructuresandvortexinducedvibration(VIV)ofaspring-supportedwide-D-sectioncylinderwereexperimentallyinvestigatedusinganX-wire,anovelphase-lockedparticleimagevelocimetry(PIV),andanaccelerationsensoratalowspeedwindtunnel.Comparedwiththefixedcase,the2P(twopair)vortexmodeasdefinedbyGovardhanandWilliamson(2000)ratherthanS(singlevortex)modeexistsinthewake.Thevelocitydeficitbehindthecylinderismuchlargerthanthatoffixedcase.Themeandragcoefficientincreasesfrom1.42forthefixedcaseto1.64forthevibratingcase.TheReynoldsstresspresentsevendistributionandsmallwithincreaseddistanceofX/D=-2toX/D=-10.Thepowerspectradensitybasedonacceleratorandhotwiredatapresentsahighlightidentical.Itshowsthatafterastronginteractionthecylindervibrationandthevortexsheddingcometoastablestate.Thevortexsheddingistotallylockedonandcontrolledbythecylindervibration.

  • 标签: 涡激振动 实验 加速度传感器 粒子图像测速仪 横流 功率谱密度
  • 简介:Anewmethodforfabricatingorderedporoussiliconisreported.Atwo-dimensionalsilicananospherearrayisusedasatemplatewithahydrofluoricacid-hydrogenperoxidesolutionforetchingthenanospheres.Theinitialdiameteranddistributionoftheholesintheresultingporoussiliconlayeraredeterminedbythesizeanddistributionofthesilicananospheres.Thecorrosiontimecanbeusedtocontrolthedepthsoftheholes.ItisfoundthatthepresenceofaSiO_2layer,formedbytheoxidationoftheroughinternalsurfaceofthehole,istheprimaryreasonallowingthecorrosiontoproceed.Ultravioletreflectionandthermalconductivitymeasurementsshowthatthediameteranddistributionoftheholeshaveagreatinfluenceonpropertiesoftheporoussilicon.

  • 标签: 二氧化硅层 制备方法 多孔硅 有序 模板 二维
  • 简介:ThispaperdiscussesthesolutionsofthelinearmatrixequationBTXB=Donsomelinearmanifolds.Somenecessaryandsufficientconditionsfortheexistenceofthesolutionandtheexpressionofthegeneralsolutionaregiven.Andalsosomeoptimalapproximationsolutionsarediscussed.

  • 标签: 半定解 线性矩阵方程 线性流形 半定矩阵 正交矩阵
  • 简介:Comparativemolecularfieldanalysis(CoMFA),athreedimensionalquantitativestructure-activityrelationship(3D-QSAR)methodwasappliedtoaseriesofdiindolylmethane(DIM)analogstostudytherelationshipbetweentheirstructureandtheirinductionofCYP1A1-associatedethoxyresorufin-O-deethylase(EROD)activity.ADISCOmodelofpharmacophorewasdervedtoguidethesuperpositionofthecompounds.Thecoefficientofcross-validation(q^2)andnoncross-validation(r^2)forthemodelestablishedbythestudyare0.827and0.988respectively,thevalueofvarianceratio(F)is103.53andstandarderrorestimate(SEE)is0.044.ThesevaluesindicatethattheCoMFAmodelderivedissignificantandmighthaveagoodpredictionforthecatalyticactivityofDIMcompounds.Asaconsequence,thepredictedactivityvaluesofnewdesignedcompoundswereallhigherthanthatofthereportedvalue.

  • 标签: 3D-QSAR COMFA CYPIAI 比较分子场分析 三维定量构效关系 模拟分析
  • 简介:Thispaperisconcernedwithexperimentalandnumericalresearchon3DflowpastprismaticturbinecascadeSE1050(knowninQNETnetworkasopentestcaseSE1050).Theprimarygoalwastoassesstheinfluenceoftheinletvelocityprofileontheflowstructuresintheinterbladechannelandontheflowfieldparametersatthecascadeexitandtocomparethesefindingstoresultsofnumericalsimulations.Investigationsof3Dflowpastthecascadewithnon-uniforminletvelocityprofilewerecarriedoutbothexperimentallyandnumericallyatsubsonic(M2is=0.8)andattransonic(M2is=1.2)regimeatdesignangleofincidence.Experimentaldatawasobtainedusingatraversingdevicewithafive-holeconicalprobe.Numerically,the3DflowwassimulatedbyopensourcecodeOpenFOAMandin-housecode.AnalysesofexperimentaldataandCFDsimulationshaverevealedthedevelopmentofdistinctivevortexstructuresresultingfromnon-uniforminletvelocityprofile.Originofthesestructuresresultsinincreasedlossofkineticenergyandspanwiseshiftofkineticenergylosscoefficientdistribution.Differencesfoundbetweenthesubsonicandthetransoniccaseconfirmearlierfindingsavailableintheliterature.ResultsofCFDandexperimentsagreereasonablywell.

  • 标签: 实验数据 数值模拟 三维流动 涡轮叶栅 跨音速 SE
  • 简介:许多人都了解RADAR的概念一无线电探测和测距(Ra—dioDetectionandRanging),该技术通过发射无线电频率波在大气层传输,接触目标后反射回到系统进行处理,从而得出目标距离。近年来,电子扫描阵列使这一技术发生了革命性转变,可将无线电波以特定方向传输,无需机械移动。

  • 标签: 激光测距 光学相控阵 应用 无线电探测 RADAR 无线电频率
  • 简介:针对基于产品创新的企业R&D联盟形成过程,建立了一个包含信任、企业学习能力和技术溢出率在内的博弈模型,并利用该模型分析了不同状态下企业的最优预期利润,最后得出了不同状态下企业结盟与否的结论。分析结果表明,企业的最优预期利润是信任、企业学习能力、技术溢出率的函数,这些因素对于企业结盟与否有重要影响,最优预期利润的不同导致了关于联盟形成的不同结论。

  • 标签: R&D联盟 产品创新 博弈 形成
  • 简介:用群的表示来讨论过渡金属化合物中心离子在不同对称场中d轨道分裂,并通过群链的分解,应用广义Wigner-Eckart定理来研究d轨道分裂能。然后进一步解释过渡金属硫属化合物电子结构、电学性质的特点和宝石的致色机理

  • 标签: d轨道分裂 电子结构 电导率 宝石呈色机理