Missing children in educational research: investigating school-based versus household-based assessments in India

Including all children in large-scale educational studies is a pressing concern. Omitting certain types of children from studies can lead to skewed findings that promote inaccuracies about learning levels or educational quality. Increasingly, assessments are a method for investigating the quality of education systems, but national assessments are typically conducted in classrooms and may fail to accurately represent a country’s full range of children. Alternatively, households can be a site for testing or collecting data on children’s learning. Analysing the quantitative data from two studies in India that use both household-based and school-based methods alongside data from Government of India sources, the issues with child representation in school-based assessments are examined, and the benefits of household-based research as an alternative are explored.     

顶空进样—毛细管柱气相色谱法分析啤酒的香味组分

介绍了采用毛细管柱气相色谱法分析测定啤酒中的微量挥发性香味组分.以高纯N2(99.999%)作为载气,并结合自动顶空进样技术,对啤酒中的12种微量挥发性香味组分进行定性和定量分析.结果表明:变异系数除乙醛与辛酸乙酯外均小于5%,回收率均在90%以上.该法具有较好的重现性和准确度.     

Generalized Sampling Series Approximation of Random Signals from Local Averages

Signals are often of random character since theycannot bear any information if they are predictable forany timet,they are usually modelled as stationary ran-dom processes. Balakrishnan[1]and Lloyd[2]investiga-ted the Shannon sampling on stationary randomp…     

信息技术教育的现状与展望

在对浙江省湖州、嘉兴两市部分中学的信息技术学科教学进行抽样调查的基础上，从课程设置、教材使用、教学设备、师资力量等方面分析了中学信息技术学科教学的现状，并利用统计数字揭示了该学科教学目前存在的问题，最后对该学科教学的发展前景作了进一步的探讨。     

5ayes统计中两种抽样法的比较分析

拒绝性抽样法和重要性抽样法是贝叶斯统计中两种重要的产生模拟样本的方法．两种方法之间存在一些关联,拒绝性抽样法在做一些形式上的转变后可以看作一种特殊的重要性抽样法．此外,如果将拒绝性抽样法中的包络函数作为重要性抽样法中的提议密度函数,这样新形成的抽样法会比原本的拒绝性抽样法更为有效．     

基于交流采样技术的发电机组电气性能测试系统的实现

提出了一种基于CAN总线的多级分布式发电机组电气性能测试系统。利用数字信号处理器（DSP）及三菱M16C/6N系列单片机实现了对电气参数的采集和控制,设计了一种基于AT89S52单片机的智能负载,可自动根据测试需要调节负载大小,利用工控机和组态控制软件,实现了对发电机组多个电气参数的远程实时监测和综合分析。提出了一种基于离散傅里叶变换（DFT）的同步交流采样算法,通过＂三点＂法实现了频率的跟踪,提高了采样精度。实际应用表明,系统组态灵活、测试精度高、可靠性高。     

GPS数字中频信号的模拟

研究了GPS软件接收机中GPS数字中频信号模拟的基本原理。首先,介绍了GPS信号的调制过程;其次,分析了C／A码的产生原理,并分析了信号的数字化原理;再次,讨论了GPS信号中夹杂的噪声及GPS数字中频信号的模拟过程;最后,针对不同环境分别对GPS数字中频信号频谱进行了仿真实验。结果表明,其频谱比较准确。既能从图中看出调制过程,也能够求出其载波频率,为以后的研究奠定了重要的基础。     

The importance of teachers' emotions and instructional behavior for their students' emotions – An experience sampling analysis

The present study focuses on the relationship between teachers' emotions, their instructional behavior, and students' emotions in class. 149 students (55% female, M age = 15.63 years) rated their teachers' emotions (joy, anger, anxiety) and instructional behavior, as well as their own emotions in an experience-sampling study across an average of 15 lessons in four different subject domains. Intraindividual, multilevel regression analyses revealed that perceived teachers' emotions and instructional behavior significantly predicted students' emotions. Results suggest that teachers' emotions are as important for students' emotions as teachers' instructional behavior. Theoretical implications for crossover theory and practical recommendations for teachers are discussed.     

δ-方法在统计量渐近分布中的应用??

δ-方法是概率论与数理统计教学中一极其重要的引理,在统计量渐近分布中用处十分广泛。本文主要通过实例说明了δ-方法在统计量极限分布中的应用。     

如何讲好时域取样定理

时域取样定理是"信号与系统"和"数字信号处理"等课程的重要内容,但是,目前高等院校普遍使用的国内外经典教材对这部分内容论述不够清晰,没有证明连续时间信号与离散时间信号频谱的关系,尤其是引入了理想冲激取样过程,物理意义不明确,影响了学生理解。本文对时域取样定理进行了深入的思考,提出了两种讲解思路,教学实践表明,对增强学生对该内容的理解,提高授课质量,有较强的针对性。