Wavelet thresholding via a Bayesian approach

We discuss a Bayesian formalism which gives rise to a type of wavelet threshold estimation in nonparametric regression. A prior distribution is imposed on the wavelet coefficients of the unknown response function, designed to capture the sparseness of wavelet expansion that is common to most applications. For the prior specified, the posterior median yields a thresholding procedure. Our prior model for the underlying function can be adjusted to give functions falling in any specific Besov space. We establish a relationship between the hyperparameters of the prior model and the parameters of those Besov spaces within which realizations from the prior will fall. Such a relationship gives insight into the meaning of the Besov space parameters. Moreover, the relationship established makes it possible in principle to incorporate prior knowledge about the function's regularity properties into the prior model for its wavelet coefficients. However, prior knowledge about a function's regularity properties might be difficult to elicit; with this in mind, we propose a standard choice of prior hyperparameters that works well in our examples. Several simulated examples are used to illustrate our method, and comparisons are made with other thresholding methods. We also present an application to a data set that was collected in an anaesthesiological study.     

荀子幸福观析论

作为战国末年先秦儒家思想的集大成者，荀子对幸福问题有了更深刻的认识。一方面，他在孔、孟之后看到了社会幸福与个人幸福之间的关系，认为只有国家昌盛个人才有可能得到幸福；另一方面，他看到了祸福的相互转化和德福悖论，他主张修养德行来促进幸福，但他亦勇于正视社会现实中个人主观努力与实际结果的差距。他认为致福的路径：一是加强自身修养；二是审时度势，保持一颗平常心，不汲汲于物质幸福，而更多地去追求精神快乐。因此，荀子的幸福思想是对先秦儒家既有幸福理论的改造。     

一种快速全局运动估计算法

为了对全局运动进行准确快速的估计,在对全局运动估计算法进行研究的基础上,提出了一种快速全局运动估计算法。该算法基于非线性密度估计,采用了六参数的仿射模型。为了提高计算速度,采用了3层金字塔进行多分辨率计算,而且在每层迭代计算中,将基于块的外点去除算法与特征点提取算法相结合,这样既加快了算法的速度,又提高了计算结果的准确性。全局运动估计的实验结果表明,该算法在速度和准确性上具有一定的优势。     

燃油税的国际比较及对我国的启示

能源的短缺和环境的恶化极大地制约了我国可持续发展,节能问题成为燃眉之急;此外,在国内费改税的浪潮中,解决交通和车辆收费的混乱问题也成为改革的重点之一。通过开征燃油税解决以上问题不失为一个良方,但我国的特殊国情导致燃油税开征的困难重重,本文通过燃油税的国际比较探索我国开征燃油税的合理方案。     

Semiparametric Mixtures of Generalized Exponential Families

Abstract.  A semiparametric mixture model is characterized by a non-parametric mixing distribution Q (with respect to a parameter θ ) and a structural parameter β common to all components. Much of the literature on mixture models has focused on fixing β and estimating Q . However, this can lead to inconsistent estimation of both Q and the order of the model m . Creating a framework for consistent estimation remains an open problem and is the focus of this article. We formulate a class of generalized exponential family (GEF) models and establish sufficient conditions for the identifiability of finite mixtures formed from a GEF along with sufficient conditions for a nesting structure. Finite identifiability and nesting structure lead to the central result that semiparametric maximum likelihood estimation of Q and β fails. However, consistent estimation is possible if we restrict the class of mixing distributions and employ an information-theoretic approach. This article provides a foundation for inference in semiparametric mixture models, in which GEFs and their structural properties play an instrumental role.     

说“通”

"通"的思想方法,主要是在正确反映客观事物及其运动的种种联系的基础上,将大脑储存的知识经验"盘活",使之融会贯通,灵活运用,在为人处事、治学作艺中发挥积极作用。"通"在"经验转移"、"思维统摄"和"通感"三个层面上的表现,要求既敏锐又准确地认识事物之间的联系。要达到"通"的境界,首先必须"突破一点",即在自己的专业与本职工作中"弄通",进而达到"一通百通"。     

基于小波变换的自适应公钥数字水印

利用小波变换良好的时频局部特性,提出了一种基于小波变换的自适应公钥数字水印设计方案。数据的所有者利用私钥向数据中嵌入版权信息,任何数据使用者可以利用公钥从接收到的数据中提取版权信息。水印的嵌入强度可根据原始图像自身的特点自适应调节,水印的提取也不需要原始图像。实验结果表明该算法具有良好的不可视性和抗联合图像专家组压缩、剪切、滤波等攻击的能力。     

浅谈学习型组织的建立与运行

建立学习型组织共有十大步骤,根据学习型组织的定义要素和特征,建立学习型组织应做好基础性工作,并建立有利于组织学习的机制,从根本上实现企业向学习型组织转化。     

WOLA滤波器组信道化接收机技术

多相DFT滤波器组是实现信道化接收机的一种高效结构,但是该结构要求信道数目与抽取倍数必须相等,限制了接收机参数设计的灵活性。该文将WOLA滤波器组引入信道化接收机,以信号的平移代替窗函数的平移,对加权、叠接、相加后的信号进行DFT变换,实现了多相DFT滤波器组的相同功能,又解除了抽取倍数与信道数目的约束关系,是多相DFT滤波器组的一种推广形式。仿真结果验证了WOLA滤波器组在实现信道化接收机时的有效性。     

哈佛的光荣梦想与迷失变革

哈佛是当今世界上最好的大学,但在其光环的背后,也有对于本科教学不够重视、通识教育不断调整、教育公平不断完善、校园建设不断扩张、官僚行政不断强化、学术自由遭到干涉、资金短缺、学生不满等问题,建议我国高校要创新办学理念、克服核心刚性、科学借鉴他国经验,更加冷静、客观、坦然地面对现实和谋划未来。