Mie scattering of a partially coherent beam

The scattering of a partially coherent electromagnetic beam by a dielectric sphere is described. Two methods are presented: a coherent mode representation and a spherical harmonics expansion. In the case of a distant blackbody source, the coherent modes are plane waves and the scattered intensity is obtained by a convolution of the classical Mie results over the source surface.     

X‐Ray Scattering and Imaging Studies of Electrode Structure and Dynamics

We will review structures and dynamics of electrode interfaces studied in situ using x‐ray scattering and imaging techniques. The examples cover single‐crystal and nanocrystal structures relevant to electrocatalytic activities, anodic oxidation and corrosion, aqueous dissolution reactions, surface reconstructions, and surface modifications by under potential deposition. The x‐ray techniques include the widely used traditional surface x‐ray scattering, such as crystal truncation rods and x‐ray reflectivity, as well as recently developed resonance surface scattering, coherent surface x‐ray photon correlation spectroscopy, coherent x‐ray Bragg diffraction imaging, and surface ptychography. Results relevant to various electrochemical phenomena will be highlighted.     

两纠缠原子与相干态光场相互作用过程中光场的量子特性

采用时间演化算符和数值计算方法,研究了两全同二能级纠缠原子与相干态光场相互作用过程中光场的量子特性,结果表明:两原子初始纠缠度和相干态光场强度对系统光场的二阶相干性质和压缩效应有很大的影响.     

载流有界等离子体柱中的剪切阿尔芬波涡旋

本文采用二流体方程组，研究低β（ｍｅ／ｍｉ＜＜β＜＜１）载流有界等离子体柱中的非线性剪切阿尔芬波，求得一类新的电磁涡旋解。在这类解中，扰动电场和扰动磁场的局域结构由单极部分和多极部分组成，而扰动密度是多极涡旋结构。这些相干结构以一定的角速度整体地绕等离子体柱轴运行。对于本文所取的参数，平衡电流对扰动电磁场和密度的涡旋结构无影响。     

Weak-Injective Modules of Weak Dimension at Most One

We consider modules over integral domains R. A main purpose is to show that certain module properties assumed on R-modules of weak dimension ≤1 imply that these properties are shared by all modules in the category of R-modules.

Also we prove several results involving modules of weak dimension ≤1.     

Kondo coupling and Curie temperature of in the coherent potential approximation

The ferromagnetism of Ga_1-xMn_xAs is studied in the coherent potential approximation (CPA). In this work, we used the exact Hilbert transformation of the face-centered cubic (fcc) density of states (DOS), which is different from the usual semi-circle DOS employed in previous works. Using Weiss molecular theory, we obtained a nonlinear relation of Curie temperature with respect to Kondo coupling. Our calculated T_C agrees very well with measured values.     

Control of spontaneous emission spectra via an external coherent magnetic field in a cycle-configuration atomic medium

We theoretically study the features of the spontaneous emission spectra in a coherently driven cold four-level atomic system with a cyclic configuration. It is shown that a few interesting phenomena such as spectral-line narrowing, spectral-line enhancement, and spectral-line suppression can be realized in our system. Interestingly enough, the spectral-line enhancement and suppression can be controlled just by appropriately modulating the phase, the frequency, and the intensity of an external coherent magnetic field, respectively. This investigation may find applications in high-precision spectroscopy. An erratum to this article is available at .     

An ESPRIT-like algorithm for coherent DOA estimation based on data matrix decomposition in MIMO radar

A direction-of-arrival (DOA) estimation method for coherent sources is presented for MIMO radar. It uses symmetrical array mode for both the transmit and receive arrays and reconstructs a special data matrix from the range-compressed receive data. In the reconstructed matrix, the signal term is a Toeplitz matrix with the rank only related to the DOAs of the signals and independent with their coherency. Taking the noise term into account, the average method of multiple pulses is utilized to obtain the signal and noise subspaces. And then the DOA can be resolved via the SVD-based ESPRIT algorithm. Furthermore, the presented method is also useful in spatial colored noise scenario for MIMO radar. Theoretical and numerical simulations show the effectiveness of the proposed algorithm.     

Time-resolved PIV measurements of the interaction of polystyrene beads with near-wall-coherent structures in a turbulent channel flow

Time-resolved PIV measurements were performed in a dilute particle-laden flow tracking near-neutrally buoyant polystyrene beads and the velocity field of a near wall turbulent boundary layer. Data were taken in a vertical light sheet aligned in the streamwise direction at the center of a horizontal, closed loop, transparent square water channel facility. In addition, low speed measurements were performed characterizing the effects of the dispersed phase on mean and turbulence flow quantities. Reynolds shear stress slightly differed from clear water conditions whereas fluid mean and rms values were not affected. A case study for several beads revealed a clear relation between their movement and near-wall coherent structures. Several structures having 2D vorticity signatures of near-wall hairpin vortices and hairpin packets, directly affected bead movement. A statistical analysis showed that the mean streamwise velocity of ascending beads lagged behind the mean fluid velocity and bead rms values were higher than fluid ones. Particle Reynolds numbers based on the magnitude of the instantaneous relative velocity vector peaked near the wall; values not exceeding 100, too low for vortex shedding to occur. Quadrant analysis showed a clear preference for ascending beads to reside in ejections while for descending beads the preference for sweeps was less.