共查询到20条相似文献,搜索用时 15 毫秒
1.
We consider logarithmic conformal field theories near a boundary and derive the general form of one and two point functions. We obtain results for arbitrary and two dimensions. Application to two-dimensional magnetohydrodynamics is discussed. 相似文献
2.
从声波的散射理论出发,利用级数展开法得到高斯波束的波束因子,推导其对阻抗边界下离轴球形粒子声辐射力.针对刚性球与液体球两种球形粒子进行数值模拟,与自由空间的情况进行比较.讨论边界反射系数、粒子与边界距离、束腰半径以及离轴角度与距离等对声辐射力的影响.仿真结果表明:边界反射系数的增大会引起声辐射力的增加,但不改变峰值的位置;在合适的频率处,可以产生负向声辐射力;声辐射力随粒子与边界距离呈周期性变化;束腰半径的影响主要体现在中高频;随着粒子偏离传播轴的距离和角度增大,声辐射力明显衰减.该研究为利用高斯波束实现对粒子的操纵提供理论基础. 相似文献
3.
We consider the short-time heat content asymptotics for oblique boundary conditions. The first few coefficients in the asymptotic expansion are calculated. 相似文献
4.
A. Afaq Azmat Iqbal Amin Ur Rahman Naveed Khan Fazal-e- Aleem M. Mushraf Ansari 《Brazilian Journal of Physics》2016,46(5):489-495
Photodetachment of negative ions near surfaces is of great interest in view of its fundamental significance and technological applications. We reinvestigate the dynamics of photoelectrons in H? photodetachment near a partially reflecting spherical surface by the semiclassical closed-orbit theory. Reflection parameter R and curvature K is used to observe inelastic and spherical effects of the surface, respectively. The classical action is evaluated from the photodetached electron trajectories incident normally at the surface, arising simultaneously from the source and its image. The derived analytical formula of photodetachment cross section correctly recovers the results of reflective spherical surface published recently based on theoretical imaging method. 相似文献
5.
We study a two-level atom in interaction with a real massless scalar quantum field in a spacetime with a reflecting boundary. We calculate the rate of change of the atomic energy for the atom. The presence of the boundary modifies the quantum fluctuations of the scalar field, which in turn modifies the rate of change of the atomic energy. It is found that the modifications induced by the presence of a boundary make the spontaneous radiation rate of an excited atom to oscillate near the boundary and this oscillatory behaviour may offer a possible opportunity for experimental tests for geometrical (boundary) effects in flat spacetime. 相似文献
6.
Heat Kernel Asymptotics of Zaremba Boundary Value Problem 总被引:1,自引:0,他引:1
The Zaremba boundary-value problem is a boundary value problem for Laplace-type second-order partial differential operators
acting on smooth sections of a vector bundle over a smooth compact Riemannian manifold with smooth boundary but with discontinuous
boundary conditions, which include Dirichlet boundary conditions on one part of the boundary and Neumann boundary conditions
on another part of the boundary. We study the heat kernel asymptotics of Zaremba boundary value problem. The construction
of the asymptotic solution of the heat equation is described in detail and the heat kernel is computed explicitly in the leading
approximation. Some of the first nontrivial coefficients of the heat kernel asymptotic expansion are computed explicitly.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
We compute the first five terms in the short-time heat trace asymptotics expansion for an operator of the Laplace type with transfer boundary conditions using the functorial properties of these invariants. 相似文献
8.
Zhao Liu 《中国物理C(英文版)》1997,21(1):25-33
The oscillator algebra with reflecting boundary is constructed together with its Fock space,and is generalized to the cases with generalized statistics and multicomponent.Such oscillators depend manifestly on the reflection factor and the statistical(exchange)factor.By construction,the Fock space of such oscillator algebras can be obtained by certain projection operation.from that of the usual bosonic oscillator without reflection condition. 相似文献
9.
The fractal dimension of particles is commonly evaluated from complete particle boundaries. In this work, a study has been made of the self-similar nature of complete and incomplete boundary profiles of a range of morphologically different copper powders. Boundary images were captured from SEM micrographs of particle boundaries at a range of magnifications up to nearly 14000X. An algorithm was developed to compute the fractal dimension of boundary segments. This algorithm was tested against the Koch Island fractal, and was found to give excellent estimates of the fractal dimension. For the particle system studied, the boundary fractal was found to be sensitive to magnification with appreciable drops in value at high magnification. This demonstrates that the particles studied did not have true fractal boundaries and the use of fractal theory to study particle surface roughness must be used with caution. 相似文献
10.
Spontaneous Emission of an Inertial Multi-Level Atom in a Spacetime with a Reflecting Plane Boundary 下载免费PDF全文
We calculate the contributions of the vacuum fluctuations and radiation reaction to the rate of change of the mean atomic energy for a multi-level hydrogen atom in the multipolar coupling scheme in a spacetime with a reflecting boundary. Our results show that, due to the presence of the boundary, the polarizations of the atom in the parallel direction and in the normal direction are weighted differently in terms of their contributions to the spontaneous emission rate, which is an oscillating function of the atom distance from the boundary. The possible experimental implications of our result are briefly discussed. 相似文献
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12.
K. M. Daily 《Few-Body Systems》2015,56(11-12):809-822
13.
We consider small mass asymptotics of the motion of a charged particle in a potential combined with a magnetic field. After
an appropriate regularization, a Smoluchowski-Kramers type approximation is established. This approximation allows to study
long-time influence on the motion of various perturbations, deterministic and stochastic. In particular, even in the case
of pure deterministic perturbations, the long-time evolution of the perturbed system can be stochastic. 相似文献
14.
15.
Let P be an operator of Dirac type and let D=P
2 be the associated operator of Laplace type. We impose spectral boundary conditions and study the leading heat content coefficients for D. 相似文献
16.
17.
Radiative Energy Shifts of an Atom Coupled to the Derivative of a Scalar Field near a Reflecting Boundary 下载免费PDF全文
We study the radiative energy level shifts of a two-level atom in dipole coupling to the derivative of a massless scalar quantum field in a spacetime with a perfectly reflecting boundary, and calculate the contributions of vacuum fluctuations and radiation reaction to the level shift. It is found that the energy level shift of the excited state is an oscillating function of the atom's distance from the boundary and it can either be positive or negative, while that of the ground state is always positive. The most remarkable feature is that the energy level shift of the ground state behaves like 1/z^4 when the atom's distance from the boundary, z, is very large as compared to the transition wavelength of the atom, while it behaves like 1/z^3 when z is very small 相似文献
18.
A. Othman Almatroud Amina-Aicha Khennaoui Adel Ouannas Giuseppe Grassi M. Mossa Al-sawalha Ahlem Gasri 《Entropy (Basel, Switzerland)》2020,22(12)
This article proposes a new fractional-order discrete-time chaotic system, without equilibria, included two quadratic nonlinearities terms. The dynamics of this system were experimentally investigated via bifurcation diagrams and largest Lyapunov exponent. Besides, some chaotic tests such as the 0–1 test and approximate entropy (ApEn) were included to detect the performance of our numerical results. Furthermore, a valid control method of stabilization is introduced to regulate the proposed system in such a way as to force all its states to adaptively tend toward the equilibrium point at zero. All theoretical findings in this work have been verified numerically using MATLAB software package. 相似文献
19.
Elaine T. McDonald 《Journal of statistical physics》2001,102(1-2):97-113
These results explore the asymptotic behavior of the density of a system of coalescing random walks where particles begin from only a subspace of the integer lattice and are allowed to walk anywhere on the lattice. They generalize results by Bramson and Griffeath from 1980.(1) Since the probability that a given site is occupied depends on how far that site is from the originating subspace, the density of the system at a given time must be re-defined. However, the general idea is still that if the density is larger than we expect at a given time, more coalescing events will occur, and the density will correct itself over time. 相似文献
20.
In this paper we investigate the phenomenon of particle production of massles scalar field, in a model of spacetime where the chronology horizon could be formed, using the method of complex time WKB approximation (CWKB). For the purpose, we take two examples in a model of spacetime, one already discussed by Sushkov, to show that the mode of particle production near chronology horizon possesses the similar characteristic features as are found while discussing particle production in time dependent curved background. We get identical results as that obtained by Sushkov in this direction. We find, in both the examples studied, that the total number of particles remain finite at the moment of the formation of the chronology horizon. 相似文献