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 共查询到20条相似文献,搜索用时 140 毫秒
1.
Analysis of the causes of formation of negative loss factors   总被引:2,自引:0,他引:2  
I-IatroductionStatisticalEnergyAnalysis(SEA)isakindofeffective,simpleanddirectapproachforan-alyzingvibrationandsound,andithasbeenfoundwidelyapplicationsinanalysisofmechanicalnoiseandvibrationcolltrolsince198osl1-4].However,forgeneralindustrialmachineswhichalwayconsistofcomPlexandheaVystructures,thedeterminationmethodsofSEAparametersintheclassicalSEAtheoryareinapplicable[5]because:(1)SEAparametersofthesekindsofstructuresaredifficulttoobtainfromthetheory(2)theconditionofconservativeandweak…  相似文献   

2.
郑仕标 《中国物理》2004,13(10):1707-1710
We propose a scheme to observe the decoherence of a mesoscopic superposition of two coherent states in the motion of a trapped ion. In the scheme the ion is excited by two perpendicular lasers tuned to the ion transition. The decoherence is revealed by the decrease of the correlation between two successive measurements of the internal state of the ion after relevant laser-ion interaction.  相似文献   

3.
We investigate the factors that affect synchronizability of coupled oscillators on scale-free networks. Using the memory Tabu search (MTS) algorithm, we improve the eigen-ratio Q of a coupling matrix by edge intercrossing. The numerical results show that the synchronizatlon-improved scale-free networks should have distinctive both small average distance and larger clustering coefficient, which are consistent with some real-world networks. Moreover, the synchronizability-improved networks demonstrate the disassortative coefficient.  相似文献   

4.
The eccentricity of the centre of mass from the geometric centre of a spherical attracting mass in determining the Newtonian gravitational constant G is tested by means of an electronic balance. The experimental result shows that the eccentricity of the sample is about 0.31 μm with uncertainty of 0.05μm. Two density distribution models are discussed to estimate the uncertainty to G by the eccentricities of the attracting masses.  相似文献   

5.
Observation of spontaeous Polarization of tourmaline   总被引:10,自引:0,他引:10       下载免费PDF全文
Since Tetsujiro kubo indirectly found the spontaneous polarization of tourmaline through absorbing copper ions in copper sulfate aqueous solutions in 1980s,there is no other evidence to demonstrate the existence of the spontaneous polarization in tourmaline.It was ound that after a tourmaline particle was bombarded by electron beams,a spot appeared on the surface of the sample,and that one half of the spot was brighter than the other half under scanning electron icroscope.After touraline was treated for 2h at 1223K and then bombarded by electron beams,the bombardment spot did not appear because the crystal structure of tourmaline is destroyed.The existence of the bombardment spot accounts for the spontaneous polarization.The shape and brightness of the bombardment spot not only shows the existence of a surface electric filed induced by spontaneous polarization.but also the relation with the direction of the crystal plane of tourmaline.  相似文献   

6.
吴惠彬  梅凤翔 《中国物理 B》2010,19(3):30303-030303
This paper studies the symmetry of Lagrangians of nonholonomic systems of non-Chetaev’s type.First,the definition and the criterion of the symmetry of the system are given.Secondly,it obtains the condition under which there exists a conserved quantity and the form of the conserved quantity.Finally,an example is shown to illustrate the application of the result.  相似文献   

7.
The vibration phenomenon during pulsed laser heating of micro-beams is investigated. The beam is made of silicon and is heated by a laser pulse with a non-Gaussian temporal profile and with an ultrashort pulse duration of 2ps, which incites vibration due to the thermoelastic damping effect. This coupled thermoelastic problem is solved using an analytical-numerical technique based on the Laplace transformation. The damping ratio and resonant frequency shift ratio of beams due to the air damping effect and the thermoelastic damping effect are also examined and discussed.  相似文献   

8.
This paper proposes a scheme to teleport an arbitrary mixture of diagonal states of multiqutrit via classical correlation and classical communication. To teleport an arbitrary mixture of diagonal states of N qutrits, N classically correlated pairs of two qutrits are used as channel. The sender (Alice) makes Fourier transform and conditional gate (i.e., XOR(3) gate) on her qutrits and does measurement in appropriate computation bases. Then she sends N ctrits to the receiver (Bob). Based on the received information, Bob performs the corresponding unitary transformation on his qutrits and obtains the teleported state. Teleportation of an arbitrary mixture of diagonal states of multiqudit is also discussed.  相似文献   

9.
王敖金  胡坤生 《中国物理快报》2002,19(11):1727-1729
Membrane viscosity of the reconstituted vesicles was calibrated by rotational diffusion of bacteriorhodopin(BR) in dimyristoylphosphatidylcholine(DMPC) and egg phosphatidylcholine(PC) vesicles.Rotational diffusion of BR in the vesicles was measured by flash-induced absorption anisotropy decay.BR was,for the first time ,reconstituted successfully into DMPC and egg PC vesicles,From the measurement of flash-induced absorption anisotropy decay of BR,the value of rotational diffusion coefficient D was obtained from each curve fitting by a global fitting procedure and ,in turn,membrane viscosity η was estimated from D.The results have shown that membrane viscosity is temperature-dependent,It was decreased as temperature increased,but a transition occurred in the region of the respective phase transition of DMPC and egg PC,respectively,The decrease of η was fast near the phase transition for DMPC and egg PC.Few effects of lipid/BR ratio and glycerol or sucrose in suspension medium on membrane viscosity were found.  相似文献   

10.
lIntroductionThephysicalmodelofinhomogeneousplanewaveofacousticsisusedtostudythewavepropagationinthermoviscoelasticmaterials.Inrecentyears,alotofworksandsomesignificafltresultshavebeenpublished,inwhichthegeneration,propagation,reflectionandrefractiononaninterfacefortheinhomogeneousplanewaveaswellastomeasurethecoefficientsofviscosityofmaterialsbyusingthemodelofinhomogeneousplanewavewerec..ce...dt1-2o].Inthispaper,under.thehighfrequency,westudytheellipticalmotionofparticleinthefieldofinhomogeneo…  相似文献   

11.
徐瑞莉  方建会  张斌 《物理学报》2013,62(15):154501-154501
本文研究离散差分序列变质量Hamilton系统的Lie对称性与Noether守恒量. 构建了离散差分序列变质量Hamilton系统的差分动力学方程, 给出了离散差分序列变质量Hamilton系统差分动力学方程在无限小变 换群下的Lie对称性的确定方程和定义, 得到了离散力学系统Lie对称性导致Noether守恒量的条件及形式, 举例说明结果的应用. 关键词: 离散力学 Hamilton系统 Lie对称性 Noether守恒量  相似文献   

12.
施沈阳  黄晓虹  张晓波  金立 《物理学报》2009,58(6):3625-3631
研究离散差分Hamilton系统的Lie对称性与Noether守恒量. 根据扩展的时间离散力学变分原理构建Hamilton系统的差分动力学方程.定义离散系统运动差分方程在无限小变换群下的不变性为Lie对称性, 导出由Lie对称性得到系统离散Noether守恒量的判据. 举例说明结果的应用. 关键词: 离散力学 差分Hamilton系统 Lie对称性 Noether守恒量  相似文献   

13.
王肖肖  韩月林  张美  贾利群 《中国物理 B》2013,22(2):20201-020201
Lie symmetry and conserved quantity deduced from Lie symmetry of Appell equations in a dynamical system of relative motion with Chetaev-type nonholonomic constraints are studied.The differential equations of motion of the Appell equation for the system,the definition and criterion of Lie symmetry,the condition and the expression of generalized Hojman conserved quantity deduced from Lie symmetry for the system are obtained.The condition and the expression of Hojman conserved quantity deduced from special Lie symmetry for the system under invariable time are further obtained.An example is given to illustrate the application of the results.  相似文献   

14.
孙现亭  张耀宇  张芳  贾利群 《物理学报》2014,63(14):140201-140201
研究完整系统Appell方程Lie对称性的共形不变性与Hojman守恒量.在时间不变的特殊无限小变换下,定义完整系统动力学方程的Lie对称性和共形不变性,给出该系统Lie对称性共形不变性的确定方程及系统的Hojman守恒量,并举例说明结果的应用.  相似文献   

15.
王肖肖  孙现亭  张美玲  解银丽  贾利群 《中国物理 B》2011,20(12):124501-124501
The Lie symmetry and Hojman conserved quantity of Nielsen equations in a dynamical system of relative motion with nonholonomic constraint of the Chetaev type are studied. The differential equations of motion of the Nielsen equation for the system, the definition and the criterion of Lie symmetry, and the expression of the Hojman conserved quantity deduced directly from the Lie symmetry for the system are obtained. An example is given to illustrate the application of the results.  相似文献   

16.
Special Lie symmetry and Hojman conserved quantity of Appell equations for a holonomic system are studied. Appell equations and differential equations of motion for holonomic mechanic systems are established. Under special Lie infinitesimal transformations in which the time is invariable, the determining equation of the special Lie symmetry and the expressions of Hojman conserved quantity for Appell equations of holonomic systems are presented. Finally, an example is given to illustrate the application of the results.  相似文献   

17.
带有附加项的广义Hamilton系统的Mei对称性   总被引:7,自引:0,他引:7       下载免费PDF全文
贾利群  郑世旺 《物理学报》2006,55(8):3829-3832
研究带附加项的广义Hamilton系统的Mei对称性的定义和判据,给出系统Mei对称性为Lie对称性的充分必要条件. 通过Lie对称性间接导出具有Mei对称性且带有附加项的广义Hamilton系统运动微分方程的Hojman守恒量. 举例说明结果的应用. 关键词: 附加项 广义Hamilton系统 Mei对称性 Hojman守恒量  相似文献   

18.
方建会  张斌  张伟伟  徐瑞莉 《中国物理 B》2012,21(5):50202-050202
In this paper,we investigate whether the Lie symmetry can induce the Mei conserved quantity directly in a nonconservative Hamilton system and a theorem is presented.The condition under which the Lie symmetry of the system directly induces the Mei conserved quantity is given.Meanwhile,an example is discussed to illustrate the application of the results.The present results have shown that the Lie symmetry of a nonconservative Hamilton system can also induce the Mei conserved quantity directly.  相似文献   

19.
This paper focuses on studying the relation between a velocity-dependent symmetry and a generalized Lutzky conserved quantity for a holonomic system with remainder coordinates subjected to unilateral constraints. The differential equations of motion of the system are established, and the definition of Lie symmetry for the system is given.The conditions under which a Lie symmetry can directly lead up to a generalized Lutzky conserved quantity and the form of the new conserved quantity are obtained, and an example is given to illustrate the application of the results.  相似文献   

20.
陈蓉  许学军 《中国物理 B》2012,21(9):94501-094501
In this paper, the relation of the conformal invariance, the Noether symmetry, and the Lie symmetry for the Hamilton system is discussed in detail. The definition of the conformal invariance for Hamilton systems is given. The relation between the conformal invariance and the Noether symmetry is discussed, the conformal factors of the determining expressions are found by using the Noether symmetry, and the Noether conserved quantity resulted from the conformal invariance is obtained. The relation between the conformal invariance and the Lie symmetry is discussed, the conformal factors are found by using the Lie symmetry, and the Hojman conserved quantity resulted from the conformal invariance of the system is obtained. Two examples are given to illustrate the application of the results.  相似文献   

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