任意四边形网格上解辐射输运方程的一种数值方法

解二维辐射输运问题时,对于矩形网格,用Sn菱形(diamond)格式处理十分简单有效,但该格式不能直接用于非矩形网格,而辐射流体力学计算往往要求在非矩形网格上进行.本文讨论任意四边形网格的辐射输运数值方法,给出一种全正的子网格平衡计算格式,并进行数值计算,与矩形网格Sn菱形格式结果比较,得出本方法可行性结论.     

A numerical method for one-dimensional nonlinear sine-Gordon equation using multiquadric quasi-interpolation

In this paper, we use a univariate multiquadric quasi-interpolation scheme to solve the one-dimensional nonlinear sine-Gordon equation that is related to many physical phenomena. We obtain a numerical scheme by using the derivative of the quasi-interpolation to approximate the spatial derivative and a difference scheme to approximate the temporal derivative. The advantage of the obtained scheme is that the algorithm is very simple so that it is very easy to implement. The results of numerical experiments are presented and compared with analytical solutions to confirm the good accuracy of the presented scheme.     

Identifying the temperature distribution in a parabolice quation with overspecified data using a multiquadric quasi-interpolation method

In this paper, we use a kind of univariate multiquadric quasi-interpolation to solve a parabolic equation with overspecified data, which has arisen in many physical phenomena. We obtain the numerical scheme by using the derivative of the quasi-interpolation to approximate the spatial derivative of the dependent variable and a simple forward difference to approximate the temporal derivative of the dependent variable. The advantage of the presented scheme is that the algorithm is very simple so it is very easy to implement. The results of the numerical experiment are presented and are compared with the exact solution to confirm the good accuracy of the presented scheme.     

双曲型守恒律的一种三阶半离散中心迎风格式

对一维双曲型守恒律,给出了一种具有较小数值耗散的三阶半离散中心迎风格式.该格式以Liu和Tadmor提出的三阶无振荡重构为基础,同时考虑了波传播的单侧局部速度.时间离散用保持强稳定性的三阶Runge-Kutta方法.由于不需用Riemann解算器,避免了特征分解过程,保持了中心格式简单的优点.数值算例验证本方法可进一步减小数值耗散,提高分辨率.     

Entanglement preservation of two coupled modes

A scheme to control the evolution of any initial state in subspace {|1〉⊗|0〉,|0〉⊗|1〉} is presented. The physical system considered is the one of two coupled modes sharing one excitation. The scheme is based on unitary interactions with an auxiliary subsystem, and it can be used to preserve the initial entanglement of the system. A proposal for implementation of the scheme in the context of microwave cavity is presented.     

三维非结构网格Euler方程的LU-SGS算法及其改进

将LU-SGS隐式时间推进格式运用到非结构网格Euler方程的求解中,并对传统LU-SGS格式进行改进,结合网格重排序,发展了一套效率更高的三维Euler方程求解器.以M6机翼及超临界LANN机翼的跨音速无粘流场为算例,将改进LU-SGS格式与四步龙格-库塔显式格式及传统LU-SGS格式进行了比较.计算结果表明:所有格式的计算结果与实验结果都符合很好;传统LU-SGS格式计算效率为显式格式的3倍多,而改进LU-SGS格式计算效率为显式格式的7倍多.     

保持对称性的新积分梯度格式

针对柱坐标系下拉氏流体力学的动量方程,提出一种积分梯度格式IGTSP(Integral Gradient Total Symmetry-Preserving),它具备现有积分梯度格式IGA(Integral Gradient Average)和IGT(Integral Gradient Total)的优点,不仅克服了IGT格式不能保持柱坐标系下的一维球对称性的缺点,而且系统的总动量守恒误差为O(h),比IGA格式更好地保持系统的总动量守恒.数值试验进一步显示了该格式理论分析的优点.     

The finite volume scheme preserving extremum principle for diffusion equations on polygonal meshes

We construct a new nonlinear finite volume scheme for diffusion equation on polygonal meshes and prove that the scheme satisfies the discrete extremum principle. Our scheme is locally conservative and has only cell-centered unknowns. Numerical results are presented to show how our scheme works for preserving discrete extremum principle and positivity on various distorted meshes.     

Robust Scheme for Long-Distance Teleportation of an Unknown Atomic State

A scheme is presented for the long-distance teleportation of an unknown atomic state between two separated cavities. The scheme is based on the Raman coupling and cavity decay. In the scheme, the effective atom-cavity coupling strength is much smaller than the cavity decay rate and thus cavities of high quality factor are unnecesssary.     

An improved monotone finite volume scheme for diffusion equation on polygonal meshes

We construct a new nonlinear monotone finite volume scheme for diffusion equation on polygonal meshes. The new scheme uses the cell-edge unknowns instead of cell-vertex unknowns as the auxiliary unknowns in order to improve the accuracy of monotone scheme. Our scheme is locally conservative and has only cell-centered unknowns. Numerical results are presented to show how our scheme works for preserving positivity on various distorted meshes. Specially, numerical results show that the new scheme is robust, and more accurate than the existing monotone scheme on some kinds of meshes.     

制备囚禁离子的簇态

提出一个方案用于制备囚禁离子的簇态,制备过程中振动模仅仅是被虚激发。方案用双能级离子制备簇态,只要一束激光照射两个相互作用的离子。方案简单易行,成功几率可达到100.     

Spray algorithm without interface construction

This research is aimed to create a new and robust family of convective schemes to capture the interface between the dispersed and the carrier phases in a spray without the need to build up the interface boundary. The selection of the Weighted Average Flux (WAF) scheme is due to this scheme being designed to deal with random flux scheme which is second-order accurate in space and time. The convective flux in each cell face utilizes the WAF scheme blended with Switching Technique for Advection and Capturing of Surfaces (STACS) scheme for high resolution flux limiters. In the next step, the high resolution scheme is blended with the WAF scheme to provide the sharpness and boundedness of the interface by using switching strategy. In this work, the Eulerian–Eulerian framework of non-reactive turbulent spray is set in terms of theoretical proposed methodology namely spray moments of drop size distribution, presented by Beck and Watkins [1]. The computational spray model avoids the need to segregate the local droplet number distribution into parcels of identical droplets. The proposed scheme is tested on capturing the spray edges in modelling hollow cone sprays without need to reconstruct two-phase interface. A test is made on simple comparison between TVD scheme and WAF scheme using the same flux limiter on convective flow hollow cone spray. Results show the WAF scheme gives a better prediction than TVD scheme. The only way to check the accuracy of the presented models is by evaluating the spray sheet thickness.     

基于WENO重构的熵稳定格式求解浅水方程

针对浅水方程,提出一种数值求解格式:空间方向采用满足熵稳定条件的数值通量,并在单元交界面处进行高阶WENO重构,时间上的推进采用强稳定的Runge-Kutta方法.模拟一维和二维经典问题,结果表明,该格式具有分辨率高、基本无振荡性等特点.     

Scheme for teleportation of unknown single qubit state via continuous variables entangling channel

A new scheme for quantum teleportation of single quantum bit state with using continuous variables entangling channel is presented.In our scheme two entangled light fields are employed.An outstanding characteristic of this scheme is that one atomic state is transmitted directly to another atom without using the third atom as the mediate.     

一种模拟倾斜折射率界面光波导的新方法

针对传统离散格式下，束传播方法(BPM)模拟倾斜折射率界面出现的问题，提出了一种简明且易于编程实现的改进方案. 在横向上，通过坐标系变换和插值处理，以新颖的7点差分格式代替传统的5点差分方式；在纵向上，以四阶显式Runge-Kutta方法(RKBPM)代替二阶Crank-Nicholson算法(CNBPM)，避免了求解不规则矩阵方程，从而使计算效率显著提高. 关键词： 束传播方法 Runge-Kutta方法 光波导 脊形波导     

Generalized-Type Synchronization of Hyperchaotic Oscillators Using a Vector Signal

In this paper, a systematic and powerful scheme is proposed to address a generalized-type synchronization of a class of continuous-time systems, which includes generalized lag synchronization, generalized anticipated synchronization, and generalized synchronization. The presented scheme is used to investigate the generalized-type synchronization of the 4D hyperchaotic oscillator and the hyperchaotic oscillator with gyrators. Numerical simulations are used to verify the effectiveness of the proposed scheme. The scheme is more powerful than the scalar signal scheme due to Grassi and Mascolo.     

Generalized-Type Synchronization of Hyperchaotic Oscillators Using a Vector Signal

In this paper, a systematic and powerful scheme is proposed to address a generalized-type synchronization of a class of continuous-time systems, which includes generalized lag synchronization, generalized anticipated synchronization, and generalized synchronization. The presented scheme is used to investigate the generalized-type synchronization of the 4D hyperchaotic oscillator and the hyperchaotic oscillator with gyrators. Numerical simulations are used to verify the effectiveness of the proposed scheme. The scheme is more powerful than the scalar signal scheme due to Grassi and Mascolo.     

The generation of Entangled Qudits and their Application in Probabilistic Superdense Coding

A scheme of the generation of entangled qutrits is presented, and then is generalized to entangled ququads and entangled qudits. With the entangled qutrits, an experimental scheme of probability superdense coding with only linear optical elements is proposed. It is shown that this scheme will be suitable for the entangled ququads, even for the entangled qudits if some nonlinearity is used. This scheme is feasible in the laboratory with the current experimental technology.     

Improved measurement of polarization state in terahertz polarization spectroscopy

A calibration scheme is presented for improved polarization state measurement of terahertz pulses. In this scheme the polarization response of a two-contact terahertz photoconductive detector is accurately measured, and is used to correct for the impact of the nonidealities of the detector. Experimental results show excellent subdegree angular accuracy and at least 60% error reduction with this scheme.     

基于非结构四边形网格的WENO格式

基于非结构四边形网格发展求解双曲守恒律的三阶加权基本无振荡（WENO）格式.针对任意非结构四边形网格选取重构模板，并给出基于线性多项式的三阶线性重构.但对于一般的非结构四边形网格，会出现非常大的线性权和负权，使得非线性重构的WENO格式对光滑问题也不稳定.本文给出一个处理非常大的线性权的优化重构方法，对优化后得到的负线性权采用分裂方法进行处理.对于非线性权，提出一种考虑局部网格和物理量间断的新光滑度量因子.采用优化重构方法和新的非线性权，当前的三阶WENO格式在质量很差的网格上也具有很好的稳定性.理论的三阶精度在数值精度测试算例中得到验证，同时一范数和无穷范数的误差绝对值不依赖于网格质量；具有强间断的数值结果证明了当前格式的有效性.