Snippets of physics

It is well known in Newtonian gravity that a spherically symmetric density distribution produces a force outside it which falls as the square of the distance. Surprisingly, the converse is not true! Just be cause the force falls as inverse square outside a density distribution, you cannot conclude that it must be spherically symmetric. This article, first in a new series, explores this and related issues. This is based on an article originally published by the author in Physics Education, Vol 22, No. 4, p.263, 2006. T Padmanabhan works at IUCAA, Pune and is interested in all areas of theoretical physics, especially those which have something to do with gravity.     

技术标准背景下的专利池演进及专利申请行为

在技术标准大量引用技术专利的背景下,标准联盟以专利池运营其拥有的技术专利,专利池在标准创立及产业化中扮演着日益重要的角色。以典型专利池为研究样本,定量分析专利池中的专利数量变化与专利申请行为;研究表明,专利池创立前后是专利申请的高峰期,这些专利绝大部分为专利池的发起人所控制。对专利引用进行泊松回归,揭示出专利池中的专利质量随时间推移逐步降低,在专利池演进过程中,发起人存在策略性的专利申请行为,倾向于将低价值专利"塞入"专利池中。     

A regression analysis of researchers’ social network metrics on their citation performance in a college of engineering

Previous research shows that researchers’ social network metrics obtained from a collaborative output network (e.g., joint publications or co-authorship network) impact their performance determined by g-index. We use a richer dataset to show that a scholar's performance should be considered with respect to position in multiple networks. Previous research using only the network of researchers’ joint publications shows that a researcher's distinct connections to other researchers, a researcher's number of repeated collaborative outputs, and a researchers’ redundant connections to a group of researchers who are themselves well-connected has a positive impact on the researchers’ performance, while a researcher's tendency to connect with other researchers who are themselves well-connected (i.e., eigenvector centrality) had a negative impact on the researchers’ performance. Our findings are similar except that we find that eigenvector centrality has a positive impact on the performance of scholars. Moreover, our results demonstrate that a researcher's tendency toward dense local neighborhoods and the researchers’ demographic attributes such as gender should also be considered when investigating the impact of the social network metrics on the performance of researchers.     

How to consider fractional counting and field normalization in the statistical modeling of bibliometric data: A multilevel Poisson regression approach

The numerical-algorithmic procedures of fractional counting and field normalization are often mentioned as indispensable requirements for bibliometric analyses. Against the background of the increasing importance of statistics in bibliometrics, a multilevel Poisson regression model (level 1: publication, level 2: author) shows possible ways to consider fractional counting and field normalization in a statistical model (fractional counting I). However, due to the assumption of duplicate publications in the data set, the approach is not quite optimal. Therefore, a more advanced approach, a multilevel multiple membership model, is proposed that no longer provides for duplicates (fractional counting II). It is assumed that the citation impact can essentially be attributed to time-stable dispositions of researchers as authors who contribute with different fractions to the success of a publication’s citation. The two approaches are applied to bibliometric data for 254 scientists working in social science methodology. A major advantage of fractional counting II is that the results no longer depend on the type of fractional counting (e.g., equal weighting). Differences between authors in rankings are reproduced more clearly than on the basis of percentiles. In addition, the strong importance of field normalization is demonstrated; 60% of the citation variance is explained by field normalization.     

圆域外Poisson方程Numann问题解的积分表达式

采用分离变数法与求和函数法,得出了圆域外Poisson方程Numann问题解的积分表达式,所得结果可以用于理论分析．     

Poisson回归模型的局部影响分析

本文讨论了Poisson回归模型的局部影响分析,分别针对方差加权扰动模型、响应变量扰动模型、自变量扰动模型得到了相应的影响矩阵和影响曲率的计算公式,并通过实际例子验证了本文诊断方法的有效性。     

基于Matlab的广义线性模型建模

广义线性模型广泛用于建立非正态响应变量的模型，但它的计算依赖于计算机和数学软件．本文研究Marlab统计工具箱GLM模块的应用，给出广义线性模型的Matlab的算法，并用实例时常用的Logistic和Poisson回归给出了算法．     

熵损失函数下Poisson分布参数的Bayes估计

用类似于Bayes估计的方法,研究了在熵损失函数下Poisson分布可靠度的估计.给出了在熵损失函数下Poisson分布可靠度的Bayes估计及其可容许性,并给出了Bayes置信下限以及多层Bayes估计的表达式.     

The dynamic power management for embedded system with Poisson process

The mass of the embedded systems are driven by second batteries, not by wired power supply. So saving energy is one of the main design goals for embedded system. In this paper we present a new technique for modelling and solving the dynamic power management (DPM) problem for embedded systems with complex behavioural characteristics. First we model a power-managed embedded computing system as a controllable Flow Chart. Then we use the Poisson process for optimisation, and give the power management algorithm by the help of Dynamic Voltage Scaling (DVS) technology. At last we built the experimental model using the PXA 255 Processors. The experimental results showed that the proposed technique can achieve more than12％ power saving compared to other existing DPM techniques.     

Poisson积分的拟小波方法

用拟小波方法给出Poisson积分的数值计算公式,并用数值算例检验了我们的数值计算公式,实验表明该算法是好的.