衰落信道的空间相关性对空时编码性能的影响分析

研究空时编码的一个重要的基本假设就是各衰落信道互相独立,这一点在实际应用环境中不尽满足.本文首先详细推导了多发射天线、多接收天线间的瑞利衰落信道存在空间相关性的条件下,空时编码的成对错误概率的精确表达式,并基于此分析了其误码率性能,最后给出的空间相关条件下的空时分组编码的误码率性能仿真,验证了理论分析的有效性,同时可以得到已知信道状态信息的空时编码的相关检测方案对空间相关具有较强的鲁棒性的结论.     

一种高效的Internet上语音包丢失恢复技术

提出了一种高效的Internet上语音包丢失恢复技术,采用了基于奇偶校验码的加载式前向纠错编码(PPFEC)技术,可以在网络存在丢包情况下无损恢复大部分丢失帧信息。此外,本文将PPFEC技术与语音编码的错误隐藏技术相结合,提出了一种基于保护重要信息的FEC编码,得到更优的解码质量和带宽的性能折衷。客观音质实验表明,本文方法在各种丢包率情况下表现出良好的效果。     

激光扫平仪的误差分析与智能检测

分析了激光扫平仪的误差组成及其在等效长焦距检测系统中的三角函数表达式,介绍了检测方法,并给出了实测结果。介绍的等效长焦距智能检测系统不仅能满足不同的精度要求,而且能显著提高检测速度与效率。理论分析和实测结果表明,该仪器的角度测量不确定度优于±2″,角度分辨率优于1″。     

广义对称正则长波方程的勒让德和切贝雪夫拟谱方法

本文考虑了具齐次边界条件的广义对称正则长波方程的Legendre和Chebyshev拟谱方法，构造了半离散和全离散的Legendre和Chebyshev拟谱格式，从理论上得到了这些格式对应的最优误差估计。     

Effect of numerical integration in the DGFEM for nonlinear convection‐diffusion problems

This paper is concerned with the effect of numerical integration applied to the discontinuous Galerkin finite element discretization of nonlinear convection‐diffusion problems in 2D. In the space semidiscretization the volume and line integrals are evaluated by numerical quadratures. Our goal is to estimate the error caused by the numerical integration and to show what numerical quadratures guarantee that the accuracy of the method with exact integration is preserved. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007     

Regularized collocation method for Fredholm integral equations of the first kind

In this paper we consider a collocation method for solving Fredholm integral equations of the first kind, which is known to be an ill-posed problem. An “unregularized” use of this method can give reliable results in the case when the rate at which smallest singular values of the collocation matrices decrease is known a priori. In this case the number of collocation points plays the role of a regularization parameter. If the a priori information mentioned above is not available, then a combination of collocation with Tikhonov regularization can be the method of choice. We analyze such regularized collocation in a rather general setting, when a solution smoothness is given as a source condition with an operator monotone index function. This setting covers all types of smoothness studied so far in the theory of Tikhonov regularization. One more issue discussed in this paper is an a posteriori choice of the regularization parameter, which allows us to reach an optimal order of accuracy for deterministic noise model without any knowledge of solution smoothness.     

Superconvergence of finite volume element method for a nonlinear elliptic problem

In this article, we consider the finite volume element method for the second‐order nonlinear elliptic problem and obtain the H¹ and W^1,∞ superconvergence estimates between the solution of the finite volume element method and that of the finite element method, which reveal that the finite volume element method is in close relationship with the finite element method. With these superconvergence estimates, we establish the L^p and W^1,p (2 < p ≤ ∞) error estimates for the finite volume element method for the second‐order nonlinear elliptic problem. © 2006 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007     

最小偏差分析法在经济周期分析中的应用

利用最小偏差分析法,分析了我国GDP增长率的周期性特征,并对我国今后几年的GDP增长率进行了预测.分析的结果是:从1953—2006年,我国GDP增长率存在着7年左右的小周期,15年左右的中周期,19年左右的中长周期和28年左右的大周期,而且随着时间的推移,经济周期的波动幅度逐渐趋小,反映出经济增长的稳定性增强.预测的结果是:今后几年(2年或更长一段时间)我国GDP增长率应该保持在10%左右,波动的区间为[9%,11%].     

Bivariate Blending Thiele-Werner＇s Osculatory Rational Interpolation

Both the expansive Newton＇s interpolating polynomial and the Thiele-Werner＇s interpolation are used to construct a kind of bivariate blending Thiele-Werner＇s osculatory rational interpolation. A recursive algorithm and its characteristic properties are given. An error estimation is obtained and a numerical example is illustrated.     

对流扩散方程的一种新型特征差分方法

利用在网格内恰当选取特征线上插值点的技巧,提出了一种新型的求解对流扩散方程的特征差分方法,并给出了稳定性与收敛性分析.该方法避免了数值扩散的产生,同时具有O(τ h~2)阶的收敛阶.数值实验表明,该方法是一个高效、稳定和收敛的数值方法.