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991.
Lie symmetrical perturbation and adiabatic invariants of generalized Hojman type for Lagrange systems 下载免费PDF全文
Based on the invariance of differential equations under
infinitesimal transformations of group, Lie symmetries, exact
invariants, perturbation to the symmetries and adiabatic invariants
in form of non-Noether for a Lagrange system are presented. Firstly,
the exact invariants of generalized Hojman type led directly by Lie
symmetries for a Lagrange system without perturbations are given.
Then, on the basis of the concepts of Lie symmetries and higher
order adiabatic invariants of a mechanical system, the perturbation
of Lie symmetries for the system with the action of small
disturbance is investigated, the adiabatic invariants of generalized
Hojman type for the system are directly obtained, the conditions for
existence of the adiabatic invariants and their forms are proved.
Finally an example is presented to illustrate these results. 相似文献
992.
The impulsive control of chaotic systems, which are subjected to
unbounded exogenous perturbations, is considered. By using the
theory of impulsive differential equation together with the fuzzy
control technique, the authors propose an impulsive robust chaos
controlling criterion expressed as linear matrix inequalities
(LMIs). Based on the proposed control criterion, the procedure for
designing impulsive controllers of common (perturbed) chaotic
systems is provided. Finally, a numerical example is given to
demonstrate the obtained theoretical result. 相似文献
993.
In this paper a relativistic many-body perturbation calculation is
performed to calculate the hyperfine constants of the ground states
for lithium-like isoelectronic sequence. Zeroth-order hyperfine
constants are calculated with Dirac--Fock wavefunctions, and the
finite basis sets of the Dirac--Fock equations are constructed by B
splines. With the finite basis sets, the core polarization and the
correlation effect are evaluated. 相似文献
994.
The cross sections for the production of nuclides of element 108 via
hot fusion evaporation reactions are studied using a two-parameter
Smoluchowski equation. The optimal reactions for the synthesis of
new nuclides of element 108 with mass numbers from 266 to 271 are
suggested. The macroscopic-microscopic approach predicts a strong
deformed shell closure at Z \approx 108 and N=162. The synthesis
of more nuclides of element 108 is meaningful to the confirmation of
the existence of this deformed shell closure. 相似文献
995.
Synchronization between two different noise-perturbed chaotic systems with unknown parameters 下载免费PDF全文
In this paper, a general method of synchronizing noise-perturbed chaotic systems with unknown parameters is proposed. Based on the LaSalle-type invariance principle for stochastic differential equations and by employing a combination of feedback control and adaptive control, some sufficient conditions of chaos synchronization between these noise-perturbed systems with unknown parameters are established. The model used in the research is the chaotic system, but the method is also applicable to the hyperchaotic systems. Unified system and noise-perturbed RSssler system, hyperchaotic Chen system and nolse-perturbed hyperchaotic RSssler system are taken for illustrative examples to demonstrate this technique.[第一段] 相似文献
996.
Singular value decomposition with normalized period for magnetocaridiography signal processing 下载免费PDF全文
In this paper, we have developed an algorithm based on singular value
decomposition (SVD) for matrix. And the novel SVD algorithm with normalized
period of cardiac cycles is presented. The results from real
magnetocardiography (MCG) data processing show that the new algorithm is
better than the standard one not only in suppressing noises, but also in
providing high-fidelity MCG signals. 相似文献
997.
用微波消解法处理样品,电感耦合等离子体质谱(ICP-MS)测定了11种卷烟烟草中的6种重金属元素.研究了微波消解和ICP-MS的测定条件.方法的检出限均小于1μg/L,各元素测定的RSD(n=6)在0.29%~3.55%,样品加标回收率为90.6%~104.9%.方法简便、快速、准确,适合用于测定烟草中的微量重金属元素. 相似文献
998.
以元素单质Pb片,Te粉,Se粉为原料,乙二胺为螯合剂,采用元素溶剂热反应合成出不同形貌的PbE(E=Te,Se)微晶.对所得反应物进行了X射线衍射分析,透射电镜(TEM)与扫描电镜(SEM)的分析,光致荧光光谱的表征.分析了反应条件对合成PbE(E=Te,Se)微晶的影响,讨论了其反应过程及机理.结果表明当反应温度为180℃时,反应12h可获得高度结晶的树枝状PbTe微晶以及立方状PbSe微晶. 相似文献
999.
第4代太空防风的X射线荧光研究 总被引:8,自引:3,他引:5
利用我国发射的神舟三号飞船搭载防风种子,回收后在地面上筛选繁育,定向培育成新品种获得优良的种质资源。本文用X射线荧光光谱法(XRF)对枝叶和产量等方面占优势的第4代太空及地面组防风药用部分的元素含量进行测定和对比分析。两组样品的元素种类基本相同, 但多种矿质元素含量是太空组>地面组。尤其是太空防风中与性味功效和归经相关的Zn,Fe,Mn和Cu含量比地面组分别提高到4.39,1.23,0.84和0.90倍。太空防风矿质元素指标明显优化。XRF方法可以从整体上对中药材的元素进行测定分析和研究。利用太空搭载防风种子可以筛选出多种元素优化的防风药材新品种。 相似文献
1000.
ICP-MS/ICP-AES法快速测定转基因棉花种子中的矿质元素和重金属含量 总被引:1,自引:0,他引:1
转基因植物生理生态已成为当前的研究热点,外源基因的导入可能会造成许多无法预料的结果。文章借助ICP-MS/ICP-AES技术对我国自己研制的转基因棉花和对照种子中的矿质元素和重金属进行了研究。结果显示,转基因棉花种子中,所测量的15种矿质元素含量有12种显著低于非转基因对照,说明转基因棉花种子吸收和累积矿质元素的能力下降;而只有镁、铁、铜含量高于对照。在测定的九种重金属(有害元素)中有七种转基因抗虫棉高于对照,特别是铝和砷的含量高出许多甚至上百倍,而铬和汞两种重金属含量明显低于对照。 相似文献