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1.
§1.引言 螺旋线最早是应用在高频电子管中,近年来在长距离波导通信中,又应用了螺旋波导管来抑制杂波,因此研究的兴趣并没有降低。在[2—4]中,他们应用了各种不同的方法,来研究它的传输特性。本文的目的是从螺旋坐标出发,进一步探讨它的性质;在§4,§5中,推导了一些特征方程,可以作为计算传输常数的参考。本文提供了一些方法,对于结果只作了一些定性的说明,如果有必要的话,定量的计算留在以后再作。希望本文对于了解螺旋线上的电磁波传播性质,从比较精细的一面,有所帮助。 相似文献
2.
基于动力学同步的复杂网络结构识别是探测复杂网络拓扑性质的重要方面, 其中识别速度是一个重要但鲜有讨论问题. 首先对弱耦合条件下耦合非线性振子网络结构识别速度的问题进行了研究. 发现识别速度随耦合强度成正比增长. 通过解析讨论, 肯定了这一关系是普适的. 之后基于我们最近提出的反复驱动识别方法, 将处于同步稳定态的耦合区域也纳入研究范围. 在这种情形下存在一个最佳的时间片段的长度使识别速度达到极值. 这些结论加深了对时间序列中蕴含的拓扑结构信息量的理解. 相似文献
3.
在前文中我们已经给出小球在不均匀流场中运动时所受到的阻力。本文中我们假定泥沙和水为两种不同的介质,同时假定泥沙的浓度很小。利用前文所得到的阻力公式,我们建立了在层流状态时泥沙和水各自的运动方程组。然后利用这一组方程来讨论明渠中水流流态为层流时泥沙沉淀的情况。最后我们得到泥沙和水的相对速度在主流方向的分量并不等于零。同时我们求得根据简单假定来计算时所引起的沉积位置的误差。这个误差和水深成正比而和泥沙颗粒的大小无关。一般说来,这个误差并不是一个可以忽略的数值。 相似文献
4.
A. Bouda 《International Journal of Theoretical Physics》2009,48(3):913-923
The solution with respect to the reduced action of the one-dimensional stationary quantum Hamilton-Jacobi equation is well
known in the literature. The extension to higher dimensions in the separated variable case was proposed in contradictory formulations.
In this paper we provide new insights into the construction of the reduced action. In particular, contrary to the classical
mechanics case, we analytically show that the reduced action constructed as a sum of one variable functions does not contain
a complete information about the quantum motion. In the same context, we also make some observations about recent results
concerning quantum trajectories. Finally, we will examine the conditions in which microstates appear even in the case where
the wave function is complex. 相似文献
5.
Monodromy deformation approach to nonlinear partial differential equation is discussed in a pedestrian's way. The whole methodology is discussed on the basis of Massive Thirring Model. In the first section of our paper we discuss the basic terminologies amociated with the deformation problem. In the next part the problem is defined on the basis of the Lax pairs for the Thirring model, and it is explicitly demonstrated that how one can determine the asymptotic expansions near a regular and irregular singularity, and hence the Stokes multipliers. Thirdly we show how to determine the “third” equation in according to Its. In the determination of the asymptotic expansion we have discussed the role played by both the WKB approximation and the series solution. In the fourth section we briefly consider the problem when the nonlinear field variables are taken to be fermionic. 相似文献
6.
F. G. Alvarenga R. Fracalossi R. C. Freitas S. V. B. Gonçalves 《Brazilian Journal of Physics》2018,48(4):370-379
In this paper, we study the quantum cosmological Kantowski-Sachs model and we solve the Wheeler-DeWitt equation in minisuperspace to obtain the wave function of the corresponding universe. The perfect fluid is described by Schutz’s canonical formalism, which allows to attribute dynamical degrees of freedom to matter. The time is introduced phenomenologically using the fluid’s degrees of freedom. In particular, we adopt a stiff matter fluid. The viability of this model is analyzed and discussed. 相似文献
7.
In this paper we revisit the parabolic approximation for wave propagation in random media by taking into account backscattering.
We obtain a system of transport equations for the moments of the components of reflection and transmission operators. In the
regime in which forward scattering is strong and backward scattering is weak, we obtain closed form expressions for physically
relevant quantities related to the reflected wave, such as the beam width, the spectral width and the mean spatial power profile.
In particular, we analyze the enhanced backscattering phenomenon, that is, we show that the mean power reflected from an incident
quasi-plane wave has a maximum in the backscattered direction. This enhancement can be observed in a small cone around the
backscattered direction and we compute the enhancement factor as well as the shape of the enhanced backscattering cone. 相似文献
8.
本文在Ballhaus等人工作的基础上,利用Jameson特征理论选取两个(一个适合椭圆型,一个适合双曲型)时间相关的偏微分方程,并采用了不同的分裂法求解。本文还结合各种翼型,对跨音速小扰动方程进行了试算,得到了较理想的数值结果。 相似文献
9.
M. E. S. Alves O. D. Miranda J. C. N. de Araujo 《General Relativity and Gravitation》2008,40(4):765-774
In this work we give special attention to the bimetric theory of gravitation with massive gravitons proposed by Visser in
1998. In his theory, a prior background metric is necessary to take in account the massive term. Although in the great part
of the astrophysical studies the Minkowski metric is the best choice to the background metric, it is not possible to consider
this metric in cosmology. In order to keep the Minkowski metric as background in this case, we suggest an interpretation of
the energy–momentum conservation in Visser’s theory, which is in accordance with the equivalence principle and recovers naturally
the special relativity in the absence of gravitational sources. Although we do not present a general proof of our hypothesis
we show its validity in the simple case of a plane and dust-dominated universe, in which the “massive term” appears like an
extra contribution for the energy density. 相似文献
10.
11.
Fabrizio Colombo Graziano Gentili Irene Sabadini Daniele C. Struppa 《Journal of Geometry and Physics》2010
In a recent work, Colombo (in press) [1], we developed a functional calculus for bounded operators defined on quaternionic Banach spaces. In this paper we show how the results from the above-mentioned work can be extended to the unbounded case, and we highlight the crucial differences between the two cases. In particular, we deduce a new eigenvalue equation, suitable for the construction of a functional calculus for operators whose spectrum is not necessarily real. 相似文献
12.
L. Braicovich F. Borgatti A. Tagliaferri G. Ghiringhelli N.B. Brookes P. Ferriani C.M. Bertoni 《Applied Physics A: Materials Science & Processing》2001,73(6):679-686
We discuss the application of resonant inelastic X-ray scattering to the study of magnetic systems in the soft X-ray range.
To this end we distinguish two broad areas. In the first the layout of the experiment is such that the absorption magnetic
circular dichroism (MCD) is not zero. In the second the magnetisation is perpendicular to the incident helical beam so that
the absorption MCD is zero. In the first area we summarise published results on Fe-Co alloys and we present new data on Mn
impurities in Ni together with calculations. In the second area we summarise published results on Ni in Ni-ferrite with final
3s shell excitation and we present new results on Co-metal and Co in Co-ferrite measured with a new approach. This is based
on the incident energy dependence of the integral of the Raman spectrum in inner shell excitation (integrated resonant Raman
scattering). The potentialities and the limitations of the above methods are critically presented.
Received: 23 May 2001 / Accepted: 4 July 2001 / Published online: 5 October 2001 相似文献
13.
M. Orabi 《Few-Body Systems》2011,51(1):45-58
In previous calculations we considered some α systems with local and non-local αα potentials, and we have shown that the nonlocality nature of the cluster–cluster interaction is indispensable. In those calculations
we investigated systems in which we had a maximum of three αα pairs, and we succeeded, although it was not so easy, to remove the forbidden states with a satisfactory degree. In this
paper we try to apply the same techniques and same potentials in describing 16O as a 4α system, where now we have a six αα pairs, but unfortunately we find out that it is difficult to remove the forbidden states in this system. We therefore devote
this paper to show in some detail the difficulty we face. 相似文献
14.
Summary In this paper we analyse, with the path integral method, the diffusion of a quantum heavy particle moving in a strongly corrugated
periodic potential both in the case when the particle is interacting with a thermal bath of phonons or of electrons. In the
first case, the integration over the phonon degrees of freedom is performed exactly and in the large mass limit of the heavy
particle it gives rise to an ohmic effective action which includes a nonlocal self-interacting term whose strength is the
classical friction coefficient. In the second case, the integration over the electronic degrees of freedom is more difficult;
we are able to derive an approximate effective action for the heavy particle in two different limiting cases: i) arbitrary
large coupling between heavy particle and electrons and linear dissipation; ii) weak coupling and nonlinear dissipation. In
i) we obtain an effective action for the particle equal to that found for the phonons but with a friction coefficient given
by that of a classical heavy particle in a fermionic bath. In ii) we obtain a nonlinear, but still ohmic, dissipative term.
Using an instanton approach we evaluate the mobility (and the diffusion coefficient) of the particle, whose temperature dependence
shows a crossover from diffusive to localized behaviour at a critical value of the friction. Finally we discuss whether the
electronic and phononic frictions can reach such a critical value.
To speed up publication, the authors have agreed not to receive proofs which have been supervised by the Scientific Committee. 相似文献
15.
Within the framework of a Boltzmann-Lorentz equation, we analyze the dynamics of a granular rotor immersed in a bath of thermalized particles in the presence of a frictional torque on the axis. In numerical simulations of the equation, we observe two scaling regimes at low and high bath temperatures. In the large friction limit, we obtain the exact solution of a model corresponding to asymptotic behavior of the Boltzmann-Lorentz equation. In the limit of large rotor mass and small friction, we derive a Fokker-Planck equation for which the exact solution is also obtained. 相似文献
16.
An entangled coherent state(ECS) is one type of entanglement, which is widely discussed in the application of quantum information processing(QIP). In this paper, we propose an entanglement concentration protocol(ECP) to distill the maximally entangled W-type ECS from the partially entangled W-type ECS. In the ECP, we adopt the balanced beam splitter(BS) to make the parity check measurement. Our ECP is quite different from the conventional ECPs. After performing the ECP, not only can we obtain the maximally entangled ECS with some success probability, but also we can increase the amplitude of the coherent state. Therefore, it is especially useful in long-distance quantum communication, if the photon loss is considered. 相似文献
17.
We study the Einstein-Maxwell theory in five dimensions coupled to matter in two distinct ways. In the first we reduce the Lagrangian to an effective four-dimension one and then we couple it to matter; in the second, we introduce matter directly in the original five-dimensional theory. In both cases we use a non trivial configuration for the Maxwell potential. We find non singular solutions which present a repulsive gravitational phase. When this phase is absent, the initial singularity is unavoidable.On leave of absence from: Departamento de Fisica e Quimica, Universidade Federal do Espirito Santo, Vitoria, CEP 29000, Espirito Santo, Brazil 相似文献
18.
E. F. El Shehawey N. R. Abd El Gawaad 《International Journal of Theoretical Physics》1989,28(12):1533-1558
A charge-free surface separating two semi-infinite dielectric fluids influenced by a normal periodic electric field is subjected to nonlinear deformations. We use the method of multiple scales in order to solve the nonlinear equations. In the first-order problem we obtained Mathieu's differential equation. For the second order, we obtain the nonhomogeneous Mathieu equation and we use the method of multiple scales to obtain a sequence of equations. In the third order we obtain the second-order differential equation of periodic coefficients. Also, we obtain a formula for surface elevation. The stability conditions are determined. 相似文献
19.
Image enhancement is an important technique in computer vision. In this paper, we propose a hierarchical image enhancement approach based on the structure layer and texture layer. In the structure layer, we propose a structure-based method based on GMM, which better exploits structure details with fewer noise. In the texture layer, we present a structure-filtering method to filter unwanted texture with keeping completeness of detected salient structure. Next, we introduce a structure constraint prior to integrate them, leading to an improved enhancement result. Extensive experiments demonstrate that the proposed approach achieves higher quality results than previous approaches. 相似文献
20.
Olga Bernardi Franco Cardin Massimiliano Guzzo 《Journal of Nonlinear Mathematical Physics》2013,20(1):9-27
In Ergodic Theory it is natural to consider the pointwise convergence of finite time averages of functions with respect to the flow of dynamical systems. Since the pointwise convergence is too weak for applications to Hamiltonian Perturbation Theory, requiring differentiability, we first introduce regularized averages obtained through a stochastic perturbation of an integrable Hamiltonian flow, and then we provide detailed estimates. In particular, for a special vanishing limit of the stochastic perturbation, we obtain convergence even in a Sobolev norm taking into account the derivatives. 相似文献