求解非线性互补问题的自适应光滑信赖域方法

本文利用Fischer-Burmeister函数将非线性互补问题转化为非线性方程组,再利用Kanzow光滑逼迫函数构造光滑算予,将NCP问题转化为优化问题,然后给出了一种求解非线性互补问题的自适应光滑信赖域方法,并证明了该算法在一定条件下的全局收敛性．     

基于互信息的语言模型回退平滑算法

针对二元模型,提出了一种基于互信息的回退（MI Back-off）平滑算法．从互信息的角度,分析词之间的搭配关系,根据模型中每个二元对的互信息对其概率进行不同程度的折扣,并利用低阶模型对零概率事件进行补偿,通过极小化困惑度的原则体现新算法的合理性．在不同类别测试集下,该平滑算法与传统Katz平滑算法相比,模型困惑度下降均超过20％。     

By How Much Can Residual Minimization Accelerate the Convergence of Orthogonal Residual Methods?

We capitalize upon the known relationship between pairs of orthogonal and minimal residual methods (or, biorthogonal and quasi-minimal residual methods) in order to estimate how much smaller the residuals or quasi-residuals of the minimizing methods can be compared to those of the corresponding Galerkin or Petrov–Galerkin method. Examples of such pairs are the conjugate gradient (CG) and the conjugate residual (CR) methods, the full orthogonalization method (FOM) and the generalized minimal residual (GMRES) method, the CGNE and BiCG versions of applying CG to the normal equations, as well as the biconjugate gradient (BiCG) and the quasi-minimal residual (QMR) methods. Also the pairs consisting of the (bi)conjugate gradient squared (CGS) and the transpose-free QMR (TFQMR) methods can be added to this list if the residuals at half-steps are included, and further examples can be created easily.The analysis is more generally applicable to the minimal residual (MR) and quasi-minimal residual (QMR) smoothing processes, which are known to provide the transition from the results of the first method of such a pair to those of the second one. By an interpretation of these smoothing processes in coordinate space we deepen the understanding of some of the underlying relationships and introduce a unifying framework for minimal residual and quasi-minimal residual smoothing. This framework includes the general notion of QMR-type methods.     

我国汽车保有量预测方法浅析

对影响我国汽车市场的主要因素进行了分析,建立了以指数平滑、多元回归、神经网络为基础的汽车保有量预测模型,并对三种模型的适用性作了简单分析．     

Interpolation of Scattered 3D PTV Data to a Regular Grid

The velocity data obtained by many 3D measurement methods such as particle tracking velocimetry (PTV) are not regularly distributed in3D space. We revised three numerical schemes to interpolate the scattered velocity vectors to a regularly spaced grid. Additionally, two techniques were examined to smooth the resulting flow field. The different algorithms were tested for a synthetic data set based on the analytical solution of Burgers' vortex. To study the impact of measurement errors a Gaussian noise was superimposed on the exact solution. It was found that an interpolation scheme of higher order does not necessarily perform better than one of lower order. The most‘robust’ algorithm was used to process 3D PTV data, which were obtained from measurements of a separating flow in a forward facing step configuration. Information on the 3D streamlines and vortex structures was obtained. This revised version was published online in July 2006 with corrections to the Cover Date.     

数据库系统中一种更安全的加密机制

针对数据库中数据的保密性问题,分析了目前已有的一些加密机制,提出了一种基于密文索引的新的查询方法.此方法在查询速度上比全表或属性段脱密的方法快,在保密性上解决了基于密文索引的查询方法所存在的信息泄漏问题,并指出了基于密文索引的数据库加密机制需要进一步研究和解决的若干问题.     

Noise reduction in Raman spectra: Finite impulse response filtration versus Savitzky–Golay smoothing

Application of the finite impulse response (FIR) filtration technique for the removal of spectral noise and background broadband deformations from the Raman spectra is tested. Optimal parameters of FIR filters are found and their effectiveness is compared with the Savitzky–Golay (SG) smoothing procedure. The FIR filtration is found to be an effective procedure to treat the whole Raman spectra, but high computing power is needed. Copyright © 2007 John Wiley & Sons, Ltd.     

A kind of bivariate spline space over rectangular partition and pure bending of thin plate

The mechanical background of the bivariate spline space of degree 2 and smoothness 1 on rectangular partition is presented constructively.Making use of mechan- ical analysis method,by acting couples along the interior edges with suitable evaluations, the deflection surface is divided into piecewise form,therefore,the relation between a class of bivariate splines on rectangular partition and the pure bending of thin plate is established.In addition,the interpretation of smoothing cofactor and conformality con- dition from the mechanical point of view is given.Furthermore,by introducing twisting moments,the mechanical background of any spline belong to the above space is set up.     

VBR流磁盘I/O的优化调度及特定的缓冲计算

VBR流如视频流,由于其位率的突发性和频繁的改变,给传输系统（如网络和磁盘I/O端口）带来了巨大的挑战．VBR流的平滑调度和传输控制成为分布式多媒体应用领域内研究的热点．对于存储的视频,在连续传输中,预缓冲是平滑VBR特性非常有效和实用的方法．作者在基于为网络传输而考虑的VBR流平滑算法的基础上,讨论了考虑物理磁盘块存取特性的VBR流二次平滑调度及缓冲计算方法．首先,给出了一个在最小缓冲尺寸下的磁盘I/O调度规划算法A;然后,计算了在最大存取单元（为某种需要而设定的）不超过某一特定值时的最低缓冲需求,及在该最低缓冲需求下的一个复杂度为线性时间的磁盘I/O调度规划算法C．分析结果表明,所设计的算法能100%地利用磁盘空间．     

井间层析成像的平滑SIRT算法

井间层析成像是一个非线性反演问题 ,为了保证反演过程的稳定性 ,并提高迭代的收敛速度 ,对常规的SIRT算法进行了改进 ,即引入了平滑算子对梯度场进行动态平滑 ,并且通过线性搜索确定速度更新的步长。将这种改进的算法称为平滑SIRT算法。模型试算的结果证明 ,该方法提高了迭代的收敛速度 ,而且反演结果不受初始模型的影响 ,使反演过程的稳定性大大提高