Outside school time: an examination of science achievement and non-cognitive characteristics of 15-year olds in several countries

Elementary and secondary students spend more hours outside of class than in formal school and thus have more time for interaction with everyday science. However, evidence from a large international survey, Program of International Student Assessment (PISA) (OECD 2012), found a negative relationship between number of hours attending after-school science and science assessment scores in many countries, raising questions about why. The secondary analysis of the 2006, 2009, and 2012 PISA surveys found that in most Western countries the longer students attended after-school science programs (in a typical week), the lower their PISA standardized science test score, but the higher their positive attitudes toward future science careers, interest in science, and self-confidence in science. Several potential hypotheses for this relationship are examined and rejected. Further analysis of a causal relationship between frequent attendance in after-school programs and student achievement and attitudes should clearly identify the content of the program so that the analysis could distinguish experiences closely related to regular school curricula from the informal science activities that are not. A new analysis also should include carefully designed longitudinal surveys to test the effectiveness of informal experiences on later life choices in career and study.     

线性离散系统的H∞开环迭代学习控制器设计

针对线性离散系统,研究了开环动态迭代学习控制律的设计问题.首先给出了闭环系统的收敛充分条件,然后把迭代控制转化为H∞设计问题,最后利用线性矩阵不等式（LMI）方法求解迭代学习控制器.通过仿真实例表明了设计方法的有效性.     

基于MATLAB的大延迟系统的PID控制与Smith预估器控制的仿真分析

介绍了PID控制与Smith预估器的原理及特点，仿真实例验证了Smith预估器对大延迟系统的有效控制作用。     

浅析偷税的认定

偷税是当前普遍存在的一种税务违法行为,应当具备主体、客体、主观和客观四要件,其中主观要件在理论和执法实践中最具争议性。依据偷税概念进行分析,从行为方式上讲,偷税本身均有主观故意的成分,因此,其主观方面也是故意的。从时间界限上看,认定偷税的时间界定应当是法律规定的申报期限。自查补报、虚开发票和认定偷税的时间界限等是执法工作中分歧较大的几个具体问题,研究认定自查补报是一种偷税行为,对虚开发票的行为人,只能按发票违法进行处罚,核定征收不能认定为偷税行为。     

无声语言在体育教学中的作用

根据以往的教学经验,对无声语言的特点,以及无声语言如何在体育教学中运用进行了分析。重点剖析了在体育教学中时空感、眼神、目光、表情、站立姿势和手势等几种无声语言的巧妙运用,从而加强教师和学生之间的交往,提高教学效果。     

中国市场营销理论发展的趋势探讨及其前瞻性分析

本文依市场营销理论在中国发展的现状为参考,着重介绍在以信息技术为核心的21世纪中国市场营销理论的5大发展主题和8大发展趋势。     

一维二元光子晶体滤波特性研究

把一维时域有限差分方法用于一维二元光子晶体的滤波特性研究,数值模拟多种因素对一维二元光子晶体的滤波特性的影响,结果表明组成一维二元光子晶体的折射率、厚度、层数、入射角、光源的偏振态等都对滤波特性有影响,掺杂层位置、厚度、电磁参数都能调节其偏振滤波特性。     

中国铁路跨越式发展与武汉经济圈建设

经济圈或城市群的发展必须依托发达的综合交通网络，中国铁路跨越式发展将确立武汉作为全国四大铁路枢纽的地位，对于加快武汉经济圈建设具有非常关键的基础性作用。     

“一顶淘气鬼的帽子”——析当代艺术的愉悦性特点及负面影响

愉悦作为一种情感在艺术的殿堂是颇受人们欢迎的 ,也引起了不少人的关注。对当代艺术的愉悦性进行分析并讨论当代艺术愉悦的特点和它的影响。全文共分两个部分 :一 :愉悦性的特点 ;二 :愉悦性的负面影响     

李清照《满庭芳·小阁藏春》作年论辨

李清照的《满庭芳·小阁藏春》历来被认为是其早年之作,是一首普通的咏物词。结合李清照的生平经历、个性特征及对词中两处用典的分析,认为该词当为李清照晚年之作。词人咏残梅以自比,是她当时生活、感情的真实写照,并显示了她孤高清傲,不合流俗的性格特征,深沉地表达了其故国之思。