周期信号测量同步采样中同步误差的分析与仿真   总被引：4，自引：0，他引：4  

马宏忠  胡虔生 《东南大学学报》2000,16(1):57-63

周期信号测量中广泛采用软件同步采样测量方法,其测量误差普遍存在.本文分析了用软件实现同步采样在测量正弦电流电压有效值、有功功率的过程中产生误差的原因及误差的大小,建立了测量误差的数学模型, 并通过仿真计算,提出了减小测量误差的措施.,Software synchronous sampling is widely employed in periodic signal measurement, but measurement errors occur very commonly. This paper analyses the cause of the errors, deduces the mathematical model for the measurement errors in measuring RMS voltage, RMS current and active power using the software synchronous sampling method. Some measures to reduce the errors are put forward by simulating.  相似文献   

高师女生体育态度、体育行为与体育需求的研究     

谢小龙 《邵阳学院学报(社会科学版)》2000,(2)

随着经济、文化、教育、体育的飞速发展 ,高师女生的生活方式、娱乐生活、体育消费、体育态度、体育行为、体育需求及价值观念 ,已经发生了新的变化 .因此 ,探讨新时期高师女生的体育态度、体育行为及体育需求的现状 ,对改进高师女生的体育教学、运动训练和课外体育活动 ,对提高女生体育素质 ,推动高师体育事业的发展都具有一定的现实意义 .  相似文献   

一个新的适用于无刷直流电机驱动的单电流传感器技术     

谭徽  江建中  汪信尧  王勇 《上海大学学报(英文版)》2000,4(1):42-48

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　Ｉｔｉｓｗｅｌｌｋｎｏｗｎｔｈａｔｔｈｅｔｏｒｑｕｅｄｅｖｅｌｏｐｅｄｂｙａｐｅｒｍａｎｅｎｔｍａｇｎｅｔｂｒｕｓｈｌｅｓｓｄｃｍｏｔｏｒｉｓｐｒｏｐｏｒｔｉｏｎａｌｔｏｔｈｅｍａｇｎｉｔｕｄｅｏｆｍｏｔｏｒｐｈａｓｅｃｕｒｒｅｎｔｓ.ＴｈｉｓｌｉｎｅａｒｒｅｌａｔｉｏｎｓｈｉｐｍａｋｅｓｉｔｃｏｎｖｅｎｉｅｎｔｔｏｃｏｎｔｒｏｌＢＬＤＣＭｔｏｒｑｕｅｐｒｏｄｕｃｔｉｏｎｂｙｒｅｇｕｌａｔｉｎｇｔｈｅｍｏｔｏｒｐｈａｓｅｃｕｒｒｅｎｔｓ[1].Ｉｎｔｈｉｓｐａｐｅｒ,ｔｈ…  相似文献   

《统计学原理》教学中难点剖析及对策     

张砚 《合肥联合大学学报》1999,(3)

抽样推断和指数是《统计学原理》教学难点,本文针对专科学生的知识特点,结合教学实践经验,进行剖析和寻求对策,以期更好帮助学生理解掌握该门课程。  相似文献   

计算机控制农业   总被引：8，自引：0，他引：8  

齐文虎石玉林 《资源科学》1998,20(2):34-38

计算机控制农业来源于“精确农业”的概念和方法。它是应用3S技术（RS、GIS、GPS）把客观、科学的精确性引进县或大尺度的农业生产过程的一套集成农业生产技术。它的技术基础是3S技术的耦合。实施计算机控制农业除了大幅度降低投入成本外,还有效地降低对环境的污染。美国于80年代初期提出“精确农业”或“计算机辅助农业”的概念和设想。它起源于对农场范围内,在空间上均匀地施用农业技术措施的条件下农作物单位面积产量的空间不均匀性的认识。据1996年的报导,应用3S技术的计算机控制农业技术在美国已经受到农场主的广泛欢迎,计算机控制农业势将成为下一世纪的一种领先的农业生产技术。计算机控制农业的关键技术包括：①空间定位的农作物产量信息采集技术;②空间定位的土壤信息实时采集技术;①农田地理信息系统实时更新技术;④空间定位的农业投入控制系统;⑤实施计算机控制农业必须开发的硬件技术。在我国及早进行计算机控制农业的基础技术储备和试验研究无疑是十分必要的。在目前中国的农业运行体制条件下,可以在开发计算机控制农业所需要的上述单项硬件技术和计算机控制农业的集成技术的同时,选择华北山前平原的一个县,或新疆建设兵团农场或黑龙江大型国营农场,实施精确农业的思想。  相似文献   

High school students’ feelings: Discoveries from a large national survey and an experience sampling study     

《Learning and Instruction》2020

We investigated students' feelings at high school in a nation-wide survey of 21,678 US students (study 1), and in a four-week study using experience sampling methodology (ESM) with 472 students across 5 high schools (study 2). Both studies combined mixed methods, including open-ended questions and rating scales (e.g., PANAS). In study 1, seventy-five percent of the feelings students reported in their responses to open-ended questions were negative. The three most frequently mentioned feelings were tired, stressed, and bored. Similar findings emerged with rated items, The prevalence of negative feelings was largely similar across demographic groups. Study 2 largely corroborated the findings from study 1. Although the retrospective measures showed similar results to study 1, the in-the-moment measures also showed frequent positive feelings. We discuss the findings in light of the ‘sleep deprivation epidemic’, the achievement motivation literature, and implications for the validity of state- and trait measures of academic emotions.  相似文献   

Introducing the DYNAMICS framework of moment-to-moment development in achievement motivation     

《Learning and Instruction》2022

This article introduces a new theoretical and psychometric framework describing moment-to-moment development and inter-dependencies of achievement motivation in terms of the situated expectancy-value theory, by introducing dynamical systems concepts into this line of research. As a first empirical example of a study using this framework, we examined whether task values, costs, and success expectancies measured in a learning situation (time point t) predicted themselves and each other at the next situation (t + 1; 27 min later) within a weekly university lecture.Situational task values, expectancies, and costs were assessed using the experience sampling method in 155 university teacher training students during weekly lectures for one semester, with three surveys during each weekly lesson. Data were analyzed with multilevel cross-lagged structural equation models.There were significant auto-regressions from one learning situation to the next in success expectancies and effort costs, but not in intrinsic, utility, or attainment value nor emotional or opportunity costs. There were no significant cross-lagged effects from one situation to the next in any of the measured situated expectancy-value components.As a framework to integrate dynamical systems concepts into the research on situated learning motivation, we expect the proposed DYNAMICS framework to have a substantial impact on further theory development.  相似文献