PARALLEL FRAME SYNCHRONOUS SCHEME FOR STM-1 IN SDH NETWORKS

This paper presents a novel parallel processing-based frame synchronous methodology for 155·520 Mbit/s high speed networks according to ITU-T Recommendations G.707, G.708 and G.709. This scheme is expected to relax operating speed requirements of the circuits used in the system. The proposed methodology can be implemented using off-the-shelf low-rate integrated circuits (ICs). The performance of the devised methodology is analysed and found to be similar to that of traditional approaches. Finally, the proposed scheme is efficient and easy to implement at low cost without sacrificing performance.     

吉林移动核心网组网方案

本文简要描述了软交换设备在移动网中的应用,并就吉林移动采用软交换设备组网方案给出应用分析.同时简单介绍了上海贝尔阿尔卡特软交换设备的体系、硬件组成及特点.     

一种新的基于直觉模糊集的作战决策算法

针对现有作战决策算法存在的不足,提出了一种新的基于直觉模糊集的作战决策算法.用直觉模糊值表示可行方案指标的不确定信息,综合考虑了方案满足指标的可能性、不满足的可能性和未知的可能性3个方面的因素,给出了直觉模糊决策矩阵的建立方法和可行方案优劣度排序方法.实例及实际应用证明了算法的有效性与可行性.     

Accurate iteration-free mixed-stabilised formulation for laminar incompressible Navier–Stokes: Applications to fluid–structure interaction

Stabilised mixed velocity–pressure formulations are one of the widely-used finite element schemes for computing the numerical solutions of laminar incompressible Navier–Stokes. In these formulations, the Newton–Raphson scheme is employed to solve the nonlinearity in the convection term. One fundamental issue with this approach is the computational cost incurred in the Newton–Raphson iterations at every load/time step. In this paper, we present an iteration-free mixed finite element formulation for incompressible Navier–Stokes that preserves second-order temporal accuracy of the generalised-alpha and related schemes for both velocity and pressure fields. First, we demonstrate the second-order temporal accuracy using numerical convergence studies for an example with a manufactured solution. Later, we assess the accuracy and the computational benefits of the proposed scheme by studying the benchmark example of flow past a fixed circular cylinder. Towards showcasing the applicability of the proposed technique in a wider context, the inf–sup stable P2–P1 pair for the formulation without stabilisation is also considered. Finally, the resulting benefits of using the proposed scheme for fluid–structure interaction problems are illustrated using two benchmark examples in fluid-flexible structure interaction.     

Approximate Atomic Green Functions

In atomic and many-particle physics, Green functions often occur as propagators to formally represent the (integration over the) complete spectrum of the underlying Hamiltonian. However, while these functions are very crucial to describing many second- and higher-order perturbation processes, they have hardly been considered and classified for complex atoms. Here, we show how relativistic (many-electron) Green functions can be approximated and systematically improved for few- and many-electron atoms and ions. The representation of these functions is based on classes of virtual excitations, or so-called excitation schemes, with regard to given bound-state reference configurations, and by applying a multi-configuration Dirac-Hartree-Fock expansion of all atomic states involved. A first implementation of these approximate Green functions has been realized in the framework of Jac, the Jena Atomic Calculator, and will facilitate the study of various multi-photon and/or multiple electron (emission) processes.     

新高考方案下浙江省化学分类走班教学的研究

新高考方案给予学生更多学科选择权,同时也给化学学科带来了新的挑战。以化学教学为视角,在2014级学生实施分类走班教学的基础上,通过调查影响学生化学学考/选考的因素,探究新高考方案对化学教学的影响以及实践相应的教学策略。重点研究教学组织形式的改变、教学内容的重组融合、教学手段的多元互补、教学方式的选择优化、教学观念的更新发展。     

双颗粒沉降的动力学分析

采用格子Boltzmann-虚拟区域方法对雷诺数范围为50≤Re≤200的双颗粒自由沉降进行了直接数值模拟。首先,研究发现双颗粒最终沉降的位置分别在通道的1/4和3/4位置附近,且与颗粒的初始间距、雷诺数以及通道宽度无关。其次,重点研究了颗粒沉降过程中所受的侧向力(与沉降方向垂直),首次揭示了侧向力的振动频率与雷诺数呈二次关系,且单颗粒的结果始终小于双颗粒的结果;研究还发现侧向力的振动频率与通道宽度近似呈幂律函数关系,且幂律指数与雷诺数有关,雷诺数越大,幂律指数的绝对值越小。最后还研究了雷诺数及通道宽度对侧向力振动振幅的影响。     

改进的五阶WENO-Z+格式

WENO-ZWENO-Z$+\!$格式的性能提升依赖于新增项的作用,该项的作用是在WENO-Z格式的基础上进一步增大欠光滑子模板上的权重. 系数$\lambda$被设置用来调控该项的作用, 以避免负耗散. 本文指出了WENO-Z$+\!$格式的缺陷,其所采用$\lambda $的取值方式既不能充分发挥格式的潜力, 也未完全消除负耗散;提出$\lambda $的值应随当地流场数据变化,方能充分发挥新增项在降低数值耗散、提高分辨率上的潜力. 基于此,本文重新设计了$\lambda $的计算公式,该公式能自适应地调控新增项的作用: 只在欠光滑子模板上的权重容易过度增大的地方削弱该项的作用,以避免负耗散; 在其他地方则充分发挥新增项的作用,最大限度增大欠光滑子模板上的权重, 提高格式的分辨率.将使用该系数公式的新格式命名为WENO-Z++, 并对其数值性能进行了系统的研究.理论分析表明, 新格式在间断处具有基本无振荡(essentially non-oscillatory,ENO)特性和更低的数值耗散. 对近似色散关系(approximate dispersion relation,ADR)的研究表明,新格式有效地避免了因过度增大欠光滑子模板上的权重而带来的负耗散,其频谱特性也得到了显著提升.本文还推导了使新格式在极值点处也能保持最优阶的精度的参数设置.一系列求解Euler方程的数值试验表明,新格式的激波捕捉能力和对复杂流场结构的分辨率都显著优于原WENO-Z$+\!$格式.}     

实时共行多媒体编辑系统的一致性问题

讨论实时多媒体编辑系统中的一致性问题，特别是企望保持（intention-Preserving）一致性问题．给出了相应的变换规则和实现算法，并与undo／do／redo方案相结合给出了一个完整的解．     

解非定常不可压缩N-S方程的迭代压力Poisson方程法

１．引 言 数值求解不可压缩流体流动问题可以采用原始变量的方程作为控制方程,也可以用涡量一流函数方程作为控制方程．直接求解原始变量的不可压缩 Ｎａｖｉｅｒ—Ｓｔｏｋｅｓ方程存在一个主要困难：速度向量在每一时刻都必须满足零散度约束条件,即不可压缩性连续方程．用涡量一流函数方程求解时,连续方程自动满足,所以不存在约束条件的问题,但涡量的边界条件比较难处理,且不易应用于三维问题和带有自由表面或其它流体交界面的问题． 解决上述速度向量必须满足零散度约束条件的困难的方法有：人工压缩法［３,１７］;压力Ｐｏｉｓ…