Polygonal Approaches to the Circular Billiard: the Lyapunov Exponent

The Lyapunov exponents for three polygonal approaches to the circular billiard quasiperiodic approach, random approach and equilateral approach are calculated, the chaotic behavior in polygonal billiards is discussed. The role of singularity presented by vertex angles is quantitatively discussed. It is found that for the equilateral approach, the Lyapunov exponents vary with the side number N according to a Poisson law, i.e., λ(N) = aN exp(-βN).     

A Novel Balanced MMIC Frequency Multiplier Configuration

A characterisation method, suitable for the study of balanced MMIC frequency multiplier circuits is presented. Using this approach, a number of frequency doubler and tripler configurations are considered. The influence of the non-ideal amplitude/phase balance characteristics of some planar hybrids on the harmonic rejection properties of these circuits is discussed. Optimum circuit configurations for doubler and tripler applications are proposed. Design details for a novel generalised configuration, which can be utilised for the balancing of single-ended multiplier circuits of any order, are outlined. The harmonic generation characteristics inherent in this approach are discussed.     

浅海环境下数据同化声层析方法研究

讨论了适用于浅海的基于声速局部测量模型、声传播模型及声压场局部测量模型的声学数据同化方法,并给出了具体的执行算法。该算法根据最优化准则把局部声速和声压场的先验测量信息,以及声传播模型进行了有效地融合,提高了海洋环境参数估计的精度,为浅海声层析提供了新思路。同时,利用实验浅海声速测量数据,通过经验正交函数对实际海洋声速剖面进行了估计,并分析了各类噪声对水体声速场及海底声学参数估计精度的影响,验证了该执行算法的有效性。     

Partition functions for general multi-level systems

We describe a unified approach for calculating the partition functions of a general multi-level system with a free Hamiltonian. Particularly, we present new results for parastatistical systems of any order in the second quantized approach. Anyonic-like systems are briefly discussed.     

On the Geometry of the Berry-Robbins Approach to Spin-Statistics

Within a geometric and algebraic framework, the structures which are related to the spin-statistics connection are discussed. A comparison with the Berry-Robbins approach is made. The underlying geometric structure constitutes an additional support for this approach. In our work, a geometric approach to quantum indistinguishability is introduced which allows the treatment of singlevaluedness of wave functions in a global, model independent way.     

On the equivalence of the Fröhlich and the Bloch approaches to the electron-phonon coupling

It is shown that the Fröhlich approach for calculating electron-phonon coupling constants based on wave functions moving with the vibrating atoms can be set on a rigorous basis. This approach and the Bloch approach are shown to lead to the same physical results provided that one stays within the adiabatic approximation and considers both first and second order vertices (in the harmonic approximation). Advantages of the Fröhlich approach in past and in possible future calculations are discussed.     

Nuclear spin relaxation in solution of paramagnetic complexes with large transient zero-field splitting

A theory for paramagnetic relaxation enhancement (PRE) in systems with S> 1 at low magnetic field is developed for the case when the fluctuations of zero-field splitting (ZFS) in the molecular frame are larger than the averaged ZFS. The validity limits of the new theory are discussed, and its performance is evaluated by comparisons with the general slow-motion approach. The relevance of the new approach for the proton PRE in aqueous solution of Ni(II) is discussed.     

Anomalous hydrodynamics in two dimensions

A new approach is presented to discuss two-dimensional hydrodynamics with gauge and gravitational anomalies. Exact constitutive relations for the stress tensor and charge current are obtained. Also, a connection between response parameters and anomaly coefficients is discussed. These are new results which, in the absence of the gauge sector, reproduce the results found by the gradient expansion approach.     

Description of the photorefractive response in polymers

We employ a phenomenological approach to minimizing the assumptions underlying light-induced charge transport in polymers and expressing the steady-state photorefractive response of polymers through measurable medium characteristics. The relations obtained are shown to be useful for analysis of experimental data and theoretical predictions. The status of the phenomenological approach and its relationship with the known microscopic models are discussed.     

A simple arbitrary phase-step digital holographic reconstruction approach without blurring using two holograms

This work presents a simple approach for arbitrary phase-step digital holography using two holograms without ambiguity. Using this approach, a magnitude-contrast image is reconstructed without dc term and twin-image blurring, but the phase-contrast image is filled with phase distortion. Computer simulations are carried out to verify the proposed approach, and optical experiments are performed to validate it. The advantages, benefits and limitations of the proposed method compared to conventional two-step phase-shifting methods are also discussed herein.     

A helium cooled Fabry-Perot interferometer for infrared astronomical spectroscopy

We have built a cooled, scanning Fabry-Perot interferometer for astronomical spectroscopy in the ten micron atmospheric window. The reasons for choosing this approach are discussed and details are given of the construction and performance of the prototype instrument.     

A standing-wave approach for discussing electron transport in relativistic quantum conductors

Electron transport through a generic one-dimensional relativistic quantum conductor is discussed by calculating the quantized electron velocity as well as the quantized energy for sufficiently large values of the involved quantum number in the framework of a standing-wave approach. Fermi velocity and Fermi energy are discussed near the classical limit.     

Series Solution for Rotating Flow of an Upper Convected MaxwellFluid over a Stretching Sheet

The equations for two-dimensional flow of an upper convected Maxwell (UCM) fluid in a rotating frame are modeled. The resulting equations are first simplified by a boundary layer approach and then solved by a homotopy analysis method (HAM). Convergence of series solution is discussed through residual error curves. The results of the influence of viscoelastic and rotation parameters are plotted and discussed.     

ANGEL program: Solution of large systems of linear differential equations describing nonstationary processes using CUDA technology

This paper presents the formulation of the problem and the methodical approach for solving large systems of linear differential equations describing nonstationary processes with the use of CUDA technology; this approach is implemented in the ANGEL program. Results for a test problem on transport of radioactive products over loops of a nuclear power plant are given. The possibilities for the use of the ANGEL program for solving various problems that simulate arbitrary nonstationary processes are discussed.     

Approach to studying three-body processes

An approach to studying three-body reactions that takes consistently into account the single-collision mechanism is discussed. Specific calculations are performed for elastic and quasielastic nucleon scattering by a deuteron. The ability of the proposed simple approach to account for a wide range of experimental data suggests that it can be applied to more complicated nuclear reactions.     

Ion crystal transducer for strong coupling between single ions and single photons

A new approach for the realization of a quantum interface between single photons and single ions in an ion crystal is proposed and analyzed. In our approach the coupling between a single photon and a single ion is enhanced via the collective degrees of freedom of the ion crystal. Applications including single-photon generation, a memory for a quantum repeater, and a deterministic photon-photon, photon-phonon, or photon-ion entangler are discussed.     

Air-borne sound source characterization by patch impedance coupling approach

An approach of independent sound source characterization is discussed. The source is defined by its blocked sound pressure and surface impedance via a suitable enveloping surface. Both the blocked pressure and the impedance are made discrete using the patch averaging concept. The approach is adapted to numerical as well as experimental implementation. The characterization of a source by patches allows for acoustical sub-structuring, which in turn enables the prediction of the sound field created by a source coupled to an arbitrary environment. Numerical simulations are presented which demonstrate the validity of the approach.     

激光加载锡的动态破碎颗粒尺寸分布

基于Grady能量破坏准则,结合固体动态断裂碎块尺寸分布规律研究结果,提出了材料微层裂破碎颗粒质量分布改进模型,并对强激光加载下锡的熔化破碎实验进行了理论计算。研究显示,理论计算的锡的微层裂破碎颗粒分布数随直径变化规律与实验结果一致,模型进一步改进需考虑应变率变化等更多综合因素影响。     

激光加载锡的动态破碎颗粒尺寸分布

基于Grady能量破坏准则,结合固体动态断裂碎块尺寸分布规律研究结果,提出了材料微层裂破碎颗粒质量分布改进模型,并对强激光加载下锡的熔化破碎实验进行了理论计算。研究显示,理论计算的锡的微层裂破碎颗粒分布数随直径变化规律与实验结果一致,模型进一步改进需考虑应变率变化等更多综合因素影响。