LB方法的一个简单多速模型

研究一个简单的二维三速格子Boltzmann模型。将微观的离散模型与宏观的连续统模型相结合,以宏观的流体力学方程作为约束条件确定局部平衡分布函数。运用Chapmann-Enskog展开法和多尺度技术导出Euler方程和Navier-Stokes方程以及模型的粘性系数表达式。     

Couette流和空腔粘性流的格子Boltzmann方法模拟

采用１３速六方格子Ｂｏｌｔｚｍａｎｎ方程研究Ｃｏｕｅｔｔｅ流和空腔粘性流,模拟了在Ｐｒ＝０．９１,Ｒｅ＝１００,５０００,及Ｐｒ＝０．９１,１,１．２５而Ｒｅ＝３０００情总下Ｃｏｕｅｔｔｅ流流场的速度、温度分布,研究了热输运过程;同时用该模型拟了高雷诺数的空腔粘性流流场演化稳定后,形成的涡旋的形状及腔内温度分布情况。     

Practical Protocol for Telecloning Quantum States

We describe a protocol for telecloning a quantum state to M distant users via an （ M ＋ 1）-particle W state, In the scheme, two atoms interact simultaneously with a highly detuned cavity mode with the assistance of a classical field. The scheme is insensitive to the cavity decay and the thermal field. Moreover, the Bell-state measurement can be achieved by detecting two atoms separately. Thus telecloning can be realized in a simple way.     

飞机内部轻质隔声间的研究

一、机舱内的噪声 本文首先对比了国产某型飞机在地面静止发动和空中飞行时的噪声,结果见图1.噪声以125Hz到250Hz最强,500—1000Hz次之,2000Hz以上的高频噪声比较弱.测试所用的仪器是精密声级计和倍频程滤波器.飞行与静止发动的噪声相比,各频带约高1到2dB,A声级约高3dB.该型国产与国外同类机种对比,     

Generation of Entangled Bloch States for Two Atomic Samples Trapped in Separated Cavities

A scheme is presented for the cavities. In the scheme, each a coherent state with a small generation of entangled states for two atomic ensembles trapped in two distant atomic sample is initially in a Bloch state and the cavity mode is initially in amplitude. The dispersive dependent phase shift on the atomic system. The detection atomic samples collapse to an entangled Bloch state. atom-cavity interaction leads to a photon-number of a photon leaking from the cavities makes the two     

Preparation of cluster state in large detuned cavity

An experimentally realizable physical scheme for preparing multiqubit cluster states from a large detuned atomcavity interaction is proposed. The scheme is free of any type of measurement and insensitive to the cavity decay, and the cavity field is only virtually excited so that there is no information exchanging between atom and cavity. The time required for the gate operations is very short, which is important for decoherence. We also discuss the experimental feasibility of our scheme.     

Single-mode and tunable VCSELs in the near- to mid-infrared

Single-mode, long-wavelength vertical-cavity surface-emitting lasers （VCSELs） in the near- to mid-infrared covering the wavelength range from 1.3 to 2.3 μm are presented. This wide spectral emission range opens applications in gas sensing and optical interconnects. All these lasers are monolithically grown in the InGaAlAs-InP material system utilizing a buried tunnel junction （BTJ） as current aperture. Fabricated with a novel high-speed design with reduced parasitics, bandwidths in excess of 10 GHz at 1.3 and 1.55 μm have been achieved. Therefore, the coarse wavelength division multiplexing （CWDM） wavelength range of 1.3 to 1.6 μm at 10 Gb/s can be accomplished with one technology. Error-free data-transmission at 10 Gb/s over a fiber link of 20 km is demonstrated. One-dimensional arrays have been fabricated with emission wavelengths addressable by current tuning. Micro-electro-mechanical system （MEMS） tunable devices provide an extended tuning range in excess of 50 nm with high spectral purity. All these devices feature continuous-wave （CW） operation with typical single-mode output powers exceeding 1 mW. The operation voltage is around 1 - 1.5 V and power consumption is as low as 10 - 20 mW. Furthermore, we have also developed VCSELs based on GaSb, targeting functionality of tunable diode laser spectroscopy （TDLS） applying a 1.84-μm VCSEL. at the wavelength range from 2.3 to 3.0 μm. The systems is shown by presenting a laser hygrometer     

音质模型试验所用材料的声吸收特性模拟

本文概括介绍音质模型试验所用某些材料的声吸收模拟结果,其中包括有多孔性材料、穿孔吸声构造和薄板共振吸声构造等.模拟试验的结果表明,通过适当控制模拟条件和进行大量测试,可以寻找出某些适用于音质模型试验的材料.     

谱元方法求解正方形封闭空腔内的自然对流换热

提出谱元方法计算正方形截面封闭空腔内的自然对流问题,具体求解了原始变量速度和压力的不可压Navier-Stokes方程和温度方程,所有的求为量均采用Chebyshev谱逼近,Navier-Stokes方程和温度方程的时间离散采用时间分裂法,非线性项用4阶Runge-Kutta法,扩散项用Crank-Nicolson半隐方法,获得了与文献发表的基准解较一致的计算结果。     

Teleportation of an Unknown Atomic State via Adiabatic Passage

We propose a scheme for teleporting an unknown atomic state via adiabatic passage. Taking advantage of adiabatic passage, the atom has no probability of being excited and thus the atomic spontaneous emission is suppressed. We also show that the fidelity can reach 1 under certain condition.