简介:为提高攻击导弹同时面对目标飞机及其防御导弹情况下的命中概率,基于微分对策理论,对攻击导弹的制导律进行了设计。应对独立控制的多对象博弈问题,微分对策理论具有天然的优势,且相比于最优制导律,微分对策制导律对于目标机动估计误差和机动策略具有更强的鲁棒性。所推导的微分对策制导律进一步考虑了攻击导弹的控制有界性,且适用于攻击导弹、目标飞机和防御导弹具有高阶线性控制系统动态的情形。为验证制导律性能,进行了非线性系统仿真,结果表明该制导律在成功归避防御导弹的同时可实现趋于零脱靶量的目标拦截。攻击导弹为实现规避和攻击的双重任务,仅需要保持相比于防御导弹两倍左右的机动优势。
简介:通过分析显式有限差分格式的数值色散和数值耗散,导出一个适于有限差分格式的通用色散一耗散条件.根据群速度和耗散率之间的物理关系,确定了用以抑制数值解中伪高波数波所需要的适度耗散.在以往发展的低耗散加权基本无振荡格式WENO—CU6-M2上的应用表明,该条件可用作优化线性或非线性有限差分格式的色散和耗散的通用指导准则.此外,满足色散-耗散条件的改进WENO—CU6-M2格式还可选作低分辨率数值模拟,以三维Taylor-Green涡向湍流转捩和自相似能量衰减问题展现了它的这种能力.与经典的动态Smagorinsky亚网格尺度模型相比,在Heynolds数胁:400~3000条件下,无黏和黏性Twlor—Green涡的数值模拟结果均得到明显改善.在保持激波捕捉特性同时,与最新的隐式大涡模拟模型的计算效果相当.
简介:本文探讨了三轴转台机械系统的设计与计算问题,以惯性三轴测试转台和三轴模拟台为例,确定了多种运转状态下的有限元法计算模型,并对其进行了静、动态特性计算,比较分析了计算结果,为合理结构的设计提供了重要数据,说明了在三轴转台机械系统设计中有限元法的重要性
简介:Lithium-aluminum-cobalt-nickeloxideLiAlxCoyNi1xyO2particles,generallyusedascathodeoflithiumbattery,werepreparedbychemicalcoprecipitationfromanaqueoussolutionofLiOH,Al(NO3)3,Co(NO3)2andNi(NO3)2withNH4OH.XRD,SEMandFTIRwereusedtoexaminetheeffectofnickelcontentontheproduct.FTIRpatternsshowedthatincreaseinnickelcontentdecreasedtheabsorptionstrengthofthepeakofspinelstructureoftheproduct,attributedtotheoccupationbynickelinthealuminumsites.Particlesizeandelectricalpropertiesofthelithium-aluminum-cobalt-nickeloxide(abbreviatedasLACNO)particleswerealsodetermined.
简介:The(2+1)-dimensionalBKPequationintheHirotabilinearformisstudiedduringthiswork.WronskianandGrammiantechniquesareappliedtotheconstructionofWronskianandGrammiansolutionsofthisequation,respectively.ItisshownthatthesesolutionscanbeexpressedasnotonlyPfaffiansbutalsoWronskiansandGrammians.
简介:The1/3subharmonicsolutionfortheDuffing'sequationisinvestigatedbyusingthemethodsofharmonicbalanceandnumericalintegration.Thesensitivityofparametervariationforthetransientprocessandthetransientprocessfortheperturbanceinitialconditionsarestudied.Overandabove,theprecisionofnumericalintegrationmethodisdiscussedandthenumericalintegrationmethodiscomparedwiththeharmonicbalancemethod.Finally,asymptoticalstabilityofthepuresubharmonicoscillationselementisinspected.
简介:Inthispaper,ahigh-orderfinite-volumeschemeispresentedfortheone-dimensionalscalarandinviscidEulerconservationlaws.TheSimpson’squadratureruleisusedtoachievehigh-orderaccuracyintime.TogetthepointvalueoftheSimpson’squadrature,thecharacteristictheoryisusedtoobtainthepositionsofthegridpointsateachsub-timestagealongthecharacteristiccurves,andthethird-orderandfifth-ordercentralweightedessentiallynon-oscillatory(CWENO)reconstructionisadoptedtoestimatethecellpointvalues.Severalstandardone-dimensionalexamplesareusedtoverifythehigh-orderaccuracy,convergenceandcapabilityofcapturingshock.
简介:在现在的纸,包含三个任意的函数为的一个一般解决方案概括(2+1)维的KdV-mKdV方程,它被导出从概括(1+1)维的KdV-mKdV方程,首先借助于Wiess被介绍,小鼓,Carnevale(WTC)截断方法。然后有考虑的几条能量守恒定律的multisymplectic明确的表达被介绍为概括(2+1)维的KdV-mKdV方程基于桥的multisymplectic理论。随后,源于以便以Jacobi椭圆形的功能的合理功能模仿周期的波浪答案一般答案,一个半含蓄的multi-symplectic计划被构造那等价于Preissmann计划。从数字实验的结果,我们能断定multi-symplectic计划能精确地模仿周期的波浪答案概括(2+1)维的KdV-mKdV方程当时近似保存能量守恒定律。
简介:AhighlyefficientH1-Galerkinmixedfiniteelementmethod(MFEM)ispresentedwithlineartriangularelementfortheparabolicintegro-differentialequation.Firstly,somenewresultsabouttheintegralestimationandasymptoticexpansionsarestudied.Then,thesuperconvergenceoforderO(h2)forboththeoriginalvariableuinH1(π)normandthefluxp=uinH(div,π)normisderivedthroughtheinterpolationpostprocessingtechnique.Furthermore,withthehelpoftheasymptoticexpansionsandasuitableauxiliaryproblem,theextrapolationsolutionswithaccuracyO(h3)areobtainedfortheabovetwovariables.Finally,somenumericalresultsareprovidedtoconfirmvalidityofthetheoreticalanalysisandexcellentperformanceoftheproposedmethod.
简介:针对1点RANSAC(RandomSampleConsensus)单目视觉EKF(ExtendedKalmanFilter)算法中的滤波发散问题,分析了滤波发散的产生原因,提出了一种基于渐消记忆滤波的1点RANSAC单目视觉姿态估计算法。该算法通过在EKF滤波方程中引入加权因子,逐渐加大当前数据的权重,相应地减少旧数据的权重,有效地扼制了算法中的滤波发散问题。最后通过两组验证性实验验证说明了算法的有效性。实验结果表明:该算法能够有效地解决1点RANSAC单目视觉EKF算法中的滤波发散问题,具有更高的精度。第一组双轴联动实验,航向角的平均误差减小2.4158?,俯仰角平均误差减小0.1782?;第二组偏航轴大角度转动实验,摄像机航向角的估计误差一直保持在1.5?以内。
简介:Perovskite-typeLa1-xCexMnO3(x=0-10%)catalystswerepreparedbyflamespraypyrolysisandtheiractivitiesduringthecatalyticoxidationofbenzenewereexaminedoverthetemperaturerangeof100-450℃.ThestructuralpropertiesandreducibilityofthesematerialswerealsocharacterizedbyX-raydiffraction(XRD),N2adsorption/desorption,H2temperature-programmedreduction(H2-TPR)andX-rayphotoelectronspectroscopy(XPS).TheincorporationofCewasfoundtoimprovethebenzeneoxidationactivity,andtheperovskiteinwhichxwas0.1exhibitedthehighestactivity.Phasecompositionandsurfaceelementalanalysesindicatedthatnon-stoichiometriccompoundswerepresent.TheincorporationofCehadanegligibleeffectonthespecificsurfaceareaoftheperovskitesandhencethisfactorhaslittleimpactonthecatalyticactivity.IntroductionofCe44+resultedinmodificationofthechemicalstatesofbothB-siteionsandoxygenspeciesandfacilitatedthereducibilityoftheperovskite.ThesurfaceMn4+/Mn3+ratiowasincreasedasaresultofCe4+substitution,whileadecreaseinthesurface-adsorbedO/latticeO(Oads/Olatt)ratiowasobserved.Therelationshipbetweenthesurfaceelementalratiosandcatalyticactivitywasestablishedtoallowabetterunderstandingoftheprocessbywhichbenzeneisoxidizedoverperovskites.
简介:阴极材料李[CoxNiyMn1?x?y]为锂的O2第二等的电池被一条新线路作为一位先锋用分层的双氢氧化物(LDH)准备了。结果有-NaFeO2结构的分层的阶段在菱形的系统结晶,与有到0.47nm的夹层间距结束的空格组R-3m。X光检查光电子光谱学(XPS)被用来测量公司,Ni和Mn的氧化状态。在结构和李的电气化学的性质上改变Co/Ni/Mn比率的效果[CoxNiyMn1?x?y]O2被X光检查衍射和电气化学的测试调查了。产品表明了相当稳定的骑车行为,与为有Co/Ni/Mn=1/1/1的分层的材料的118mAh/g的一个可逆能力。