多重Fourier级数Hardy型求和的注记

给出了多重Ｆｏｕｒｉｅｒ级数的Ｈａｒｄｙ型求和在ＬＰ尺度下的逼近误差，本文的结果可以看成文［１］关于多重Ｆｏｕｒｉｅｒ级数Ｈａｒｄｙ型求和的某些已有结果的补充。     

ICT for all? Access and use of Public ICT Sites in the UK

As part of their "information age' policy agenda, the UK government sees "universal' access to information and communications technology (ICT) being achieved via new and existing public sites, where shared access to new technologies can be made available at little or no cost. State-sponsored augmentation of public ICT access in the UK has involved a variety of initiatives, most notably the recent establishment of a network of over 7,000 "UK Online Centres' located in a variety of distributed sites such as libraries, museums and colleges. Whilst there have been a number of localized case studies of users of public ICT sites, there has been little large-scale "mapping' of how these facilities are being used (and not used) by the general public. Based on a randomized household survey with 1,001 individuals in twelve research areas in the West of England and South Wales - augmented with a "booster' sample of 100 interviews with individuals carried out in public ICT sites in these areas - the present paper seeks to explore: (i) who has access to what forms of public ICT sites; and (ii) who is (and who is not) making use of different forms of public ICT sites. The survey data suggest that, in terms of people's effective access to ICT, public access sites have a relatively slight profile when compared with household and wider family access - perceived to offer ready access to ICT by only a minority of respondents. Moreover, when the use of these public ICT sites is examined, there is little evidence of public ICT sites attracting those social groups who may otherwise be excluded or marginalized from the information age. Given these findings, the paper considers the influences underlying the currently modest impact of public ICT sites on the general population and suggests changes to current public ICT provision that may prompt wider usage of these sites.     

On invariance and randomization under factor permutation in fractional factorial designs

This paper establishes the spectrum invariance of the information matrix under an arbitrary subgroup Г of the group Δ of factor permutations. In addition, it provides the randomized unbiased estimation of a linear parametric function under the composition Ω°Г, where Ω is the group of level permutations. These two results are achieved for the most practical partitioning of the whole parametric vector using the concepts of Г-closed and admissibility of a parametric subvector. Applications are given with an explicit illustration using the minimal resolution III design setting for the 2³ factorial.     

无扩频矩阵知识二维扩频系统的盲同步

针对加性白高斯噪声信道,考虑未知二维扩频矩阵的条件下,提出了一种二维扩频系统的时频同步方法。该方法利用二维扩频矩阵周期性重复的特点,先估计出频率偏差,再通过滑动暂存窗求相关矩阵最大特征值,完成信号的时间同步。计算机仿真结果验证了该方法的有效性。     

基于波动择时绩效的高维波动率估计量与预测模型研究

对协方差矩阵高频估计量和预测模型的选择,共同影响协方差的预测效果,从而影响波动择时投资组合策略的绩效。资产维数很高时,协方差矩阵高频估计量的构建会因非同步交易而丢弃大量数据,降低信息利用效率。鉴于此,将可以充分利用资产日内价格信息的KEM估计量用于估计中国股市资产的高维协方差矩阵,并与两种常用协方差矩阵估计量进行比较。进一步地,将三种估计量分别用于多元异质自回归模型、指数加权移动平均模型以及短、中、长期移动平均模型进行样本外预测,并比较在三种基于风险的投资组合策略下的经济效益。采用上证50指数中20只不同流动性成份股逐笔高频数据的实证研究发现:(1)无论是在市场平稳时期还是市场剧烈震荡期,长期移动平均模型都是高维协方差估计量预测建模的最优选择,在应用于各种波动择时策略时都可以实现最低成本和最高收益。(2)在市场平稳时期,KEM估计量是高维协方差估计的最优选择,应用于各种波动择时策略时基本都可以实现最低成本和最高收益;在市场剧烈震荡期,使用KEM估计量进行波动择时仍然可以在成本方面保持优势,但在收益上并不占优。(3)无论是在市场平稳时期还是市场剧烈震荡期,最低的成本都是在采用等风险贡献投...     

UNIX中对多种文件系统类型的支持

介绍了ＵＮＩＸ下通过虚拟文件系统接口实现多文件系统类型支持的技术，分析了ＡＩＸ操作系统中虚拟文件系统接口的实现。在此基础上对支持用户实现自己的文件系统存在的问题与困难进行了分析与研究，提出了一种较方便实现新的文件系统的方法。该方法利用了已有文件系统的现成代码，大大减少了开发工作的难度与工作量。     

数字化转型发展会提升通航企业竞争力吗? ———来自21 家企业的扎根实证分析

通用航空产业是我国的新兴产业和数字化转型发展的重点产业。运用扎根分析方法,对21 家 通航上市企业数字化转型发展状况进行剖析,归纳数字化转型发展的四种基本模式:数字化生产、数字化 研发、产品智能化、产业智能化。构建企业的竞争力评价模型,对各种形式数字化转型发展的通航企业竞 争力的提升效应及主要组成因素进行实证和比较研究。研究表明,数字化发展不同程度提高了企业竞争 力。其中,数字化研发模式、复合模式的竞争力表现较强,而数字化实践弱的通航企业竞争力表现最差。 在分析归纳各数字化发展模式特点的基础上,提出通航企业提升竞争力的路径。     

四元数矩阵之迹的几个不等式

给出了广义西空间的概念,并利用其中向量内积的性质及四元数体上方阵的酉相似理论,建立了几个自共轭四元数矩阵之迹的不等式.     

第二类优美嵌入问题

研究第二类优美嵌入的问题,得到了必要条件和在文献[5]中所期待的一些重要结果。     

应用神经网络判别二部图的方法

本文应用Hopfield神经网络模拟方法对二部图进行判别。提出了邻域矩阵的概念。将任意的连通图输入至神经网络判别系统,输出该图的邻域矩阵,对应于系统能量函数取最小值的输出状态即为二部图邻域矩阵,同时得到该二部图的顶点划分;如能量函数非最小值,则判定该图不是二部图。该判别法的核心是构造一种广义的能量函数——Liapunov函数,使原来难以解决的问题找到新的解决途径。