简介:Tobeclosetothepracticalflightprocessandincreasetheprecisionofoptimaltrajectory,asix-degree-offreedom(6-DOF)trajectoryisoptimizedforthereusablelaunchvehicle(RLV)usingtheGausspseudospectralmethod(GPM).DifferentfromthetraditionaltrajectoryoptimizationproblemwhichgenerallyconsiderstheRLVasapointmass,thecouplingbetweentranslationaldynamicsandrotationaldynamicsistakenintoaccount.Anoptimizationproblemisformulatedtominimizeaperformanceindexsubjectto6-DOFequationsofmotion,includingtranslationalandrotationaldynamics.Atwo-stepoptimalstrategyisthenintroducedtoreducethelargecalculationscausedbymultiplevariablesandconvergenceconfinementin6-DOFtrajectoryoptimization.Thesimulationresultsdemonstratethatthe6-DOFtrajectoryoptimalstrategyforRLVisfeasible.
简介:WemodeltheeffectsofweakfluctuationsontheprobabilitydensitiesandnormalizedpowersofvortexmodelsfortheBessel–Gaussphotonbeamwithfractionaltopologicalchargeintheparaxialnon-Kolmogorovturbulencechannel.Wefindthatprobabilitydensityofsignalvortexmodelsisafunctionofdeviationfromthecenterofthephotonbeam,andthefartherawayfromthebeamcenteritis,thesmallertheprobabilitydensityis.Forfractionaltopologicalcharge,theaverageprobabilitydensitiesofsignal/crosstalkvortexmodesoscillatealongthebeamradiusexceptthehalf-integerorder.Asthebeamwaistofthephotonsourcegrows,theaverageprobabilitydensityofsignalandcrosstalkvortexmodesgrowtogether.Moreover,thepeakoftheaverageprobabilitydensityofcrosstalkvortexmodesshiftsoutwardfromthebeamcenterasthebeamwaistgetslarger.Theresultsalsoshowthatthesmallerindexofnon-Kolmogorovturbulenceandthesmallergeneralizedrefractive-indexstructureparametermayleadtothehigheraverageprobabilitydensitiesofsignalvortexmodesandloweraverageprobabilitydensitiesofcrosstalkvortexmodes.Lower-coherenceradiusorbeamwaistcangiverisetolessreductionofthenormalizedpowersofthesignalvortexmodes,whichisoppositetothenormalizedpowersofcrosstalkvortexmodes.
简介:讨论了形如∫a^a+h(x-a)βf(x)dx的Gauss-Jacobi求积公式,当积分区间长度趋向于零时,确定了求积公式的余项中介点η的渐近性,并给出了校正公式,比原公式提高了两次代数精度.此外,本文的结论包含了文[3]的结果.
简介:针对传统瀑布式测试不再适用于迭代式软件开发,探索式测试有效却复用性差的问题,提出了在测试设计阶段采用质量属性、用户场景和业务逻辑(QUB)设计方法框架进行探索式测试,并结合思维导图进行测试设计.应用实例表明,该测试方法为快速迭代开发模式下的系统测试提供了-种新思路,有利于提高迭代开发测试的效率与质量.
简介:针对无限域上一维热传导方程的解析解为反常积分形式,直接计算往往比较困难.首先采用Fourier变换给出问题解析解,其次结合解析解的形式和无限域上Gauss型数值积分法精度高的优点,将半无限域上的一维热传导方程问题利用Gauss-Laguerre数值积分计算数值解,对无限域上的一维热传导方程的解析解转化为半无限域上的形式后用Gauss-Laguerre数值积分计算.实验结果表明,本文给出的数值解方法具有很高的精度.
简介:在一般Banach空间中对渐近伪压缩映象不动点的迭代问题的研究,本文使文献中相应结果得到改进和发展。
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