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1.
用推转玻尔-莫特森哈密顿量研究了A~190区20个核的55条超形变带.通过拟合实验测得的E2跃迁能量值,确定了各带的能级自旋,得到了质量参量B1和硬度参数C0.B1和C0都显示出明显的奇偶性. superdeformed bands in 20 nuclei of the A ~190 region are studied with formulas derived from the Cranking Bohr Mottelson Hamiltonian. From fitting the experimental E γ , the level spins are determined and mass parameter B 1 and rigidity parameter C 0 are obtained. The B 1 and C 0 values show clear odd even effects.  相似文献   

2.
The perturbation method in supersymmetric quantum mechanics is used to study the spheroidal wave functions' eigenvalue problem. The super-potential are solved in series of the parameter α, and the general form of all its terms is obtained. This means that the spheroidal problem is solved completely in the way for the ground eigen-value problem. The shape invariance property is proved retained for the super-potential and subsequently all the excited eigen-value problem could be solved. The results show that the spheroidal wave equations are integrable.  相似文献   

3.
本文简单介绍了美国CEBAF(连续电子束流加速器)的近况和研究方向,以及C厅将展开的研究核子内S夸克成分的极化电子与质子散射宇称破坏不对称性测量的实验,即质子味单态电形状因子G°实验. The current status and scientific goal of CEBAF (The continuous Electron Beam Accelerator Facility ) are briefly presented. The project of the measurement of the flavor Singlet form factor G°of proton at C hall is outlined. A precise measurement of Parity violating asymmetry in the scattering of polarized electron from a proton target enables one to explore the Strange quark content in the proton.  相似文献   

4.
The exact solutions of a chain of type Ⅱ are investigated.The chain of type E is first transformed to an integrable differential-difference equation,which has the Kaup-Newell spectral problem as its continuous spatial spectral problem and a Darboux transformation of the Kaup-Newell equation as its discrete temporal spectral problem.Then,with these spectral problems,a Darboux transformation of the transformed equation is constructed.Finally,as an application of the Darboux transformation,an exact solution of the transformed equation and thus the chain of type Ⅱ are presented.  相似文献   

5.
The Rosenberg problem is a typical but not too complicated problem of nonholonomic mechanical systems.The Lie-Mei symmetry and the conserved quantities of the Rosenberg problem are studied.For the Rosenberg problem,the Lie and the Mei symmetries for the equation are obtained,the conserved quantities are deduced from them and then the definition and the criterion for the Lie-Mei symmetry of the Rosenberg problem are derived.Finally,the Hojman conserved quantity and the Mei conserved quantity are deduced from the Lie-Mei symmetry.  相似文献   

6.
介绍与核内夸克-胶子分布的有关实验现象:EMC效应、核遮蔽效应、核Drel-Yan过程和J/ψ光生反应等,以及解释它们的理论模型.The experiments of the EMC effect,nuclear shadowing effect,nuclear Drell Yanprocess and J/ψ production related to the quark gluon distributions in nuclei and the theoretical models explaining them are briefly reviewed.   相似文献   

7.
In this paper, a kind of second-order two-scale (SOTS) computation is developed for conductive-radiative heat trans- fer problem in periodic porous materials. First of all, by the asymptotic expansion of the temperature field, the cell problem, homogenization problem, and second-order correctors are obtained successively. Then, the corresponding finite element al- gorithms are proposed. Finally, some numerical results are presented and compared with theoretical results. The numerical results of the proposed algorithm conform with those of the FE algorithm well, demonstrating the accuracy of the present method and its potential applications in thermal engineering of porous materials.  相似文献   

8.
评述了A~130过渡区I、Xe、Cs和Ba核的高自旋核结构研究.在这些核中观测到的极为丰富的核结构现象,如质子中子转排竞争、形状共存、带终结、带交叉延迟、Signature反转和八极关联等与这些核的价质子、价中子都位于h11/2支壳及这些核易产生γ形变有关. The studies of high spins states of A ~130 transitional I,Xe,Cs and Ba nuclei are reviewed. The variety of nuclear structure, such as proton neutron alignment competition, shape coexistance, band termination, crossing delay, signature inversion, octupole correlation, etc. observed in these nuclei is closely related to that both the valence proton and neutron of these nuclei are located in the h 11/2 subsell and the nuclei are soft against the γ deformation.  相似文献   

9.
刘晓巍  李元成 《中国物理 B》2011,20(7):70204-070204
The Rosenberg problem is a typical but not too complicated problem of nonholonomic mechanical systems. The Lie—Mei symmetry and the conserved quantities of the Rosenberg problem are studied. For the Rosenberg problem, the Lie and the Mei symmetries for the equation are obtained, the conserved quantities are deduced from them and then the definition and the criterion for the Lie—Mei symmetry of the Rosenberg problem are derived. Finally, the Hojman conserved quantity and the Mei conserved quantity are deduced from the Lie—Mei symmetry.  相似文献   

10.
Parameter Identification and Tracking of a Unified System   总被引:23,自引:0,他引:23       下载免费PDF全文
The unified chaotic system contains the Lorenz and the Chen systems as two dual systems at the two extremes of its parameter spectrum and the Lu system as a special case.The parameter identification and tracking problem of the unified system are further investigated.In particular,a novel controller is designed for avoiding the divergence of the factor 1/x.Numerical simulations are provided to show the effectiveness of these methods.  相似文献   

11.
This paper investigates a variational approach to the nonlinear stochastic inverse problem of probabilistically calibrating the Robin coefficient from boundary measurements for the steady-state heat conduction. The problem is formulated into an optimization problem, and mathematical properties relevant to its numerical computations are investigated. The spectral stochastic finite element method using polynomial chaos is utilized for the discretization of the optimization problem, and its convergence is analyzed. The nonlinear conjugate gradient method is derived for the optimization system. Numerical results for several two-dimensional problems are presented to illustrate the accuracy and efficiency of the stochastic finite element method.  相似文献   

12.
The cyclotron resonance (CR) problem for electrons over a helium film occupying the lower part of a resonator is solved. This problem is shown to represent an example of the well-known problem on the behavior of a system of coupled oscillators. For such oscillators, the coupling constant is determined as a function of the problem parameters with its minimal value in zero magnetic field and its maximal value at resonance conditions, when the cyclotron frequency coincides with one of the resonator modes. The details of the CR absorption of microwave energy by the coupled system formed by 2D electrons and a resonator are calculated. The results are discussed in application to the known CR experiments with electrons over helium.  相似文献   

13.
The three-dimensional emission ray tomography of a plasma partially scattering its self-radiation is considered. The spatial distribution of scattering density and its angular distribution are assumed to be known. The model of projection-data acquisition taking into account single and multiple scattering is constructed. In terms of this model, the problem of determining the distribution of local emission coefficients is posed. For solving this problem, the algorithm based on the Neumann-series expansion of the product of the radiative-transfer operator for a scattering medium and the operator for solving the pure emission problem was proposed. The algorithm was investigated in detail using numerical simulation.  相似文献   

14.
The problem of dividing segments into nonintersecting parts on a discrete plane is considered. An algorithm for solving this problem and methods of its further improvement are suggested. The complexity of the algorithm is analyzed.  相似文献   

15.
用于电力系统的光学电流互感器技术进展   总被引:7,自引:0,他引:7       下载免费PDF全文
介绍了光学电流测量技术的发展情况,描述了目前几种主要的互感器结构及其基本原理,并对各自存在的问题及解决途径进行了讨论。从研究现状来看,块状玻璃型传感器技术相对成熟,已经有商业产品问世;混合型传感器测量精度较高,但传感头有源电路的供电技术复杂,还没有圆满的解决方案;全光纤型是光学电流互感器发展的最终目标,目前存在的主要问题是光纤的固有线性双折射难以处理,有赖于新型光纤材料及集成光学元件的进一步发展。最后综合评述了光学电流互感器技术的发展趋势及产业化前景。  相似文献   

16.
易学华  余晓光  付凤兰 《大学物理》2007,26(3):12-15,20
回顾了经典物理和量子力学中的相位问题,着重讨论了量子几何Berry相位及在量子力学中如何进行量子相位教学的问题.  相似文献   

17.
The transmission and reflection amplitudes of an electron moving in a one dimensional potential of arbitrary form are obtained using the transfer matrix method. It is shown that the one‐dimensional scattering problem, in its most general form, can be reduced to Cauchy problem for a set of two linear differential equations.  相似文献   

18.
The existence problem of optical correlation based pattern recognition, namely its range of validity and its limitation, is discussed in this paper conjointly with the function approximation theory of neural networks. The conclusion is that only if the sets to be recognized are linearly separable (which is rare) or the subsets, in which a segmental sample of the targets is involved, are linearly separable, can the classical 4f optical correlation system carry out the task of recognition inerrably. The recognition principle of a joint transform correlator is the same as that of a 4f system, and so is its range of validities. Based on the demonstration of the existence problem of optical correlation based pattern recognition an evaluation on some important problems that were studied in this field over the past 40 years is presented explicitly.  相似文献   

19.
Symmetry reduction of a class of third-order evolution equations that admit certain generalized conditional symmetries (GCSs) is implemented. The reducibility of the initial-value problem for an evolution equation to a Cauchy problem for a system ofordinary differential equations (ODEs) is characterized via the GCS and its Lie symmetry. Complete classification theorems are obtained and some examples are taken to show the main reduction procedure.  相似文献   

20.
The inverse heat transfer problem associated with constructing multilayer material shells cloaking the presence of a cylindrical body in an externally applied temperature field is studied. As the original mathematical model, the steady-state heat equation for an anisotropic shell is used. With the help of the optimization method, this inverse problem is reduced to the corresponding control problem. A numerical algorithm of its solution based on the particle swarm optimization is proposed, and the results of numerical experiments are discussed.  相似文献   

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