共查询到20条相似文献，搜索用时 15 毫秒
1.
For the non-conservative holonomic Hamiltonian systems in phase space, the definition and criteria of the form invariance of the generalized Hamilton canonical equations were given. The relations among the form invariance, Noether symmetry and Lie symmetry were studied. The theory of the form invariance for the conservative holonomical systems was worked out. An example was given to illustrate the results. 相似文献
2.
1 Introduction Thesymmetriesofmechanicalandphysicalsystemshavecloseconnectionwiththeassociatedconservedquantities.Therearetwomethodsforseekingtheconservedquantitiesofthemechanicaland physicalsystems:theNoethersymmetry ,aninvarianceoftheHamiltonactionundertheinfinitesimaltransformationofgroups ,leadingtomanyimportantresults[1 5] ;theLiesymmetry ,aninvarianceofthedifferentialequationsundertheinfinitesimaltransformationsofgroups ,extensivelystudiedintherecentyears[6 10 ] . Since 2 0 0 0 ,Me… 相似文献
3.
Stabilization for a class of second-order switched systems with saturation constrains 总被引：1，自引：0，他引：1
This paper proposes a global stabilization method for a class of planar switched systems with input saturation constrains
by using a state feedback and switching strategy. This method is proved to be effective by analyzing the characteristics of
the trajectory of second-order linear systems with input saturation.
Project supported by the China Postdoctoral Science Foundation (Grant No.20070420643), the National Natural Science Foundation
of China (Grant No.60774059), and the Innovation Program of the Shanghai Municipal Science and Technology Commission (Grant
No.08DZ2272400) 相似文献
4.
In the present paper, the formulae for matrix Padé-type approximation were improved. The mixed model reduction method of matrix
Padé-type-Routh for the multivariable linear systems was presented. A well-known example was given to illustrate that the
mixed method is efficient.
Project supported by National Natural Science Foundation of China (Grant No. 10271074) 相似文献
5.
In this paper, dynamics in the oscillations of the relative atomic population in two periodically driven and weakly coupled Bose-Einstein eondensates (BECs) was qualitatively studied. Using the well-known Melnikov method, the conditions of existence of the periodic and chaotic coherent atomic tunnellings were given in the model. Our results indicate the typical route from bifurcation of the limited circles to chaos, and are in agreement with the previous numerical results. 相似文献
6.
梅凤翔 《商丘师范学院学报》2004,20(5):1-5
研究有多余坐标完整系统的Hojman守恒量．给出系统Lie对称性与Noether对称性，Lie对称性与形式不变性间的关系．得到特殊Lie对称性、Noether对称性以及形式不变性导致的Hojman守恒量．举例说明结果的应用． 相似文献
7.
A new generalized inverse function-valued Padé approximation (GIFPA) was defined. Existence condition of GIFPA was given and
its uniqueness theorem was proved. All possible degeneracy cases of GIFPA were discussed and constructed. An example was given
to illustrate its application.
Project supported by the National Natural Science Foundation of China (Grant No. 10271074) 相似文献
8.
The form invariance and the Lie symmetry are defined for Hamilton systems. A relation between the form invariance and the Lie symmetry is derived. The Hojman conserved quantity is constructed by using the generators of Lie symmetry. An approach to find Hojman conserved quantities in terms of the form invariance is presented. An example is given to illustrate the application of the results. 相似文献
9.
10.
The tridiagonal coefficient matrix for the ＂fixed-fixed＂ spring-mass system was obtained by changing spring length. And then a new algorithm of the inverse problem was designed to construct the masses and the spring constants from the natural frequencies of the ＂fixed-fixed＂ and ＂fixed-fres＂ spring-mass systems. An example was given to illustrate the results. 相似文献
11.
n-soliton-like solutions of three non-isospectral equations, the non-isospectral mKdV equation, the non-isospectral sine-Gordon equation and the non-isospeetral nonlinear Schroedinger equation were obtained by using the Hirota method. 相似文献
12.
Based on rational Bézier curves given by Ron Goldman, a new fractional rational Bézier curve was first defined in terms of
fractional Bernstein bases. Moreover, some basic properties were dicussed and a theorem connected to Poisson curves was obtained.
Some examples in this paper were given by the visual results.
Project supported by the National Natural Science Foundation of China (Grant No. 10271074) 相似文献
13.
Two types of molecular and polymer devices employing (2-(4′-biphenyl)-5-(4““““““““-tert-butylphenyl)-1,3,4-oxadiazole) (PBD)and poly(N-vinylcarbazole) (PVK) as electron transport and hole transport materials, respectively, have been fabricated. The structures of these two devices are ITO/PVK( 70 nm)/PBD(60 nm)/A1 and ITO/PVK: PBD (1:1 by mass, 70 nm)/A1. The formation of exciplex is evident by comparing the electroluminescence (EL) of a bi-layer device and the photoluminescence (PL) of a PVK and PBD mixed film.The maximum emission energy of exciplex evaluated is consistent with the peak emission of EL. Blue emissions from both devices are obtained. The type of exicplex is interpreted based on the energy level diagram of the bi-layer device. 相似文献
14.
Tolerance is imperative for seamless integration of CAD/CAM (Computer Aided Disign/Computer Aided Manufacture) which is just
a text attribute and has no semantics in present CAD systems. There are many tolerance types, the relations between which
are very complicated. In addition, the different principles of tolerance make study of tolerance difficult; and there may
be various meanings or interpretation for the same type of tolerance because of the literal definition. In this work, latest
unambiguous mathematical definition was applied to study, explain and clarfy: (1) the formation and representation of tolerance
zone, and (2) the formation and representation of variational elements; after which, the mathematical models of symmetry of
different tolerance principles and different interpretations were derived. An example is given to illustrate the application
of these models in tolerance analysis.
Project supported by the National Natural Science Foundation of China for Innovation Research Groups(No.60021201) and NSFC(Nos.59705022
& 69973045). 相似文献
15.
Dr. Kathryn Scantlebury 《Journal of Science Teacher Education》1995,6(3):134-142
This material is based upon work supported in part by a grant from the National Science Foundation (Grant No. HRD 945-0022).
Any opinions, findings, and conclusions or recommendations expressed in this article are those of the author and do not necessarily
reflect the views of the National Science Foundation. 相似文献
16.
A novel asymmetrical pitch system for rotary wing is presented. The pitch control characteristics are studied and analyzed.
Because elastic linkage is a key part in whole asymmetrical pitch system, in order to obtain the variation of the elastic
linkage deformation, an experimental platform mainly based on the device of micro aerial vehicles (MAVs) and a new control
system mounted on TMS320LF2407 are designed. This control system has its compacted configuration and reliability. Finally,
using this system to control the MAV for simulating the flying forward, experimental results show the MAV’s flight attitude
can be controlled based on the variation of the elastic linkage.
Project supported by the National Natural Science Foundation of China (Grant No.60605028), the National High-Technology Research
and Development Program of China (Grant No.2007AA04Z225), the Shanghai Rising-Star Program (Grant Nos.07QA14024, 07QH14006),
the Shanghai Shuguang Program (Grant No.07SG47), and the Shanghai Leading Key Laboratory of Mechanical Automation and Robotics
Science Foundation (Grant No.ZZ0805) 相似文献
17.
Ｚｉｒｃｏｎｉｕｍａｌｌｏｙｓｐｏｓｓｅｓｓｉｎｇｖｅｒｙｌｏｗａｂｓｏｒｐｔｉｏｎｆｏｒｔｈｅｒｍａｌｎｅｕｔｒｏｎｓ,ｇｏｏｄｃｏｒｒｏｓｉｏｎｒｅｓｉｓｔａｎｃｅｉｎｈｉｇｈｔｅｍｐｅｒａｔｕｒｅｗａｔｅｒ ,ａｎｄｒｅａｓｏｎａｂｌｅｍｅｃｈａｎｉｃａｌｐｒｏｐ ｅｒｔｉｅｓａｒｅｉｍｐｏｒｔａｎｔｍａｔｅｒｉａｌｓｆｏｒｎｕｃｌｅａｒｉｎｄｕｓｔｒｙ ,ａｎｄｈａｖｅｂｅｅｎｅｍｐｌｏｙｅｄａｓｎｕｃｌｅａｒｆｕｅｌｃｌａｄｄｉｎｇａｎｄａｓｓｔｒｕｃｔｕｒｅｍａｔｅｒｉａｌｓｉｎｌｉｇｈｔ… 相似文献
18.
The generalized inverse function-valued Pade approximant was defined to solve the integral equations. However, it is difficult to compute the approximants by some high-order determinant formulas. In this paper, to simplify computation of the function-valued Pade approximants, an efficient Pfaffian formula for the determinants was extended from the matrix form to the function-valued form. As an important application, a Pfaffian formula of [4/4] type Pade approximant was established. 相似文献
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20.
Samuel A. Spiegel Angelo Collins Penny J. Gilmer 《Journal of Science Teacher Education》1995,6(4):165-174
This article is based on a paper which received the “Innovations in Teaching Science Teachers” award at the 1995 meeting of
the Association for the Education of Teachers in Science. The award is made possible by Delta Education.
This material is based upon work supported in part by a grant from the National Science Foundation (Grant No. 9253170). Any
opinions, findings, and conclusions or recommendations expressed in this article are those of authors and do not necessarily
reflect the views of the National Science Foundation. 相似文献