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Noether symmetries of the nonconservative and nonholonomic systems on time scales 被引量:55
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作者 CAI PingPing FU JingLi GUO YongXin 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2013年第5期1017-1028,共12页
In this paper we give a new method to investigate Noether symmetries and conservation laws of nonconservative and nonholonomic mechanical systems on time scales , which unifies the Noether's theories of the two ca... In this paper we give a new method to investigate Noether symmetries and conservation laws of nonconservative and nonholonomic mechanical systems on time scales , which unifies the Noether's theories of the two cases for the continuous and the discrete nonconservative and nonholonomic systems. Firstly, the exchanging relationships between the isochronous variation and the delta derivatives as well as the relationships between the isochronous variation and the total variation on time scales are obtained. Secondly, using the exchanging relationships, the Hamilton's principle is presented for nonconservative systems with delta derivatives and then the Lagrange equations of the systems are obtained. Thirdly, based on the quasi-invariance of Hamiltonian action of the systems under the infinitesimal transformations with respect to the time and generalized coordinates, the Noether's theorem and the conservation laws for nonconservative systems on time scales are given. Fourthly, the d'Alembert-Lagrange principle with delta derivatives is presented, and the Lagrange equations of nonholonomic systems with delta derivatives are obtained. In addition, the Noether's theorems and the conservation laws for nonholonomic systems on time scales are also obtained. Lastly, we present a new version of Noether's theorems for discrete systems. Several examples are given to illustrate the application of our results. 展开更多
关键词 time scale Lagrange equation delta derivative Noether's theorem nonconservative and nonholonomic system
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两种基于前馈神经网络的飞行器气动参数辨识方法 被引量:4
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作者 颜楚雄 童轶男 宋加洪 《导弹与航天运载技术》 CSCD 北大核心 2020年第6期11-15,49,共6页
为避免飞行器复杂气动建模过程以及使用极大似然法时需要对初值进行估计,利用前馈神经网络能够逼近任意函数的能力,对飞行器纵向气动特性进行辨识。该方法能够避免建立气动模型与估计参数初值。利用前馈神经网络的导数特性,推导了三层... 为避免飞行器复杂气动建模过程以及使用极大似然法时需要对初值进行估计,利用前馈神经网络能够逼近任意函数的能力,对飞行器纵向气动特性进行辨识。该方法能够避免建立气动模型与估计参数初值。利用前馈神经网络的导数特性,推导了三层神经网络辨识飞行器气动参数的导数法。使用该方法与Delta法对气动参数进行了辨识。仿真结果表明前馈神经网络对气动系数具有较好的拟合效果并验证了两种参数辨识方法的有效性。通过对比发现导数法在求解气动参数时优于Delta法。 展开更多
关键词 气动辨识 前馈神经网络 导数法 delta
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On Conformable Delta Fractional Derivative on Time Scales
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作者 YOU Xue-xiao ZHAO Da-fang CHENG Jian 《Chinese Quarterly Journal of Mathematics》 2017年第2期208-215,共8页
In this paper, we introduce and investigate the concept of conformable delta fractional derivative on time scales. By using the theory of time scales, we obtain some basic properties of the conformable delta fractiona... In this paper, we introduce and investigate the concept of conformable delta fractional derivative on time scales. By using the theory of time scales, we obtain some basic properties of the conformable delta fractional derivative. Our results extend and improve both the results in [9] and the usual delta derivative. 展开更多
关键词 conformable delta fractional derivative delta derivative time scales
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测度链上一类二阶中立型微分方程的振动性 被引量:1
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作者 刘光辉 刘兰初 《河南师范大学学报(自然科学版)》 CAS CSCD 北大核心 2007年第2期42-43,共2页
考虑了测度链上二阶中立型微分方程的振动性,获得了所有解振动及所有解的delta导数振动的充分条件.
关键词 测度链 中立型 振动 delta导数
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时标上一类非线性中立型微分方程的振动性
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作者 吴会宁 张华 《价值工程》 2014年第5期313-314,共2页
考虑了时标上一类非线性二阶中立型微分方程的振动性,获得了所有解振动及所有解的delta导数振动的充分条件。
关键词 时标 中立型 振动性 delta导数
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时标意义下一阶线性动力方程及其共轭方程(英文)
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作者 宫玉荣 陶娟 项筱玲 《贵州大学学报(自然科学版)》 2006年第3期239-244,共6页
作者研究了时标意义下两类线性方程的初值问题和倒向问题,并给出了解的存在性和唯一性,同时也导出了共轭方程对及其它们之间的重要关系.
关键词 时间标度 △-导数 线性动力方程 倒向问题 共轭方程
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关于Fejer核的注记
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作者 金坚明 《西北师范大学学报(自然科学版)》 CAS 1996年第4期9-15,共7页
论证了Fejer核Fm(x,t)是拟-正定σ序列,而(x-t)αα!αtαFm(x,t)不是拟-正定σ序列;
关键词 Fejer核 拟-正定σ序列 分布导数
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