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41.
多抽样率信号处理是建立在单抽样率信号处理基础上的一类信号处理。在传输信号时,由于语音、图象、视频信号的抽样中心频率相差很大,所以需要以多种抽样频率来对信号采样来满足各种传输类型的需要。探讨了改变抽样频率的两种方式-抽取和插值的基本原理,着重探讨了整数倍抽取和内插在数字语音系统中的应用。 相似文献
42.
电力系统采样频率自适应预测算法 总被引:1,自引:0,他引:1
针对电力系统中频率变化导致的数据采集和测量误差,文章提出一种对电力系统进行交流采样的一种自适应频率预测算法,为采用DSP技术准确估计交流信号的采样频率提供了可行的计算方法。 相似文献
43.
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. 相似文献
44.
王璐 《重庆第二师范学院学报》2012,25(6):24-26,35
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。 相似文献
45.
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。 相似文献
46.
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. 相似文献
47.
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。 相似文献
48.
49.
Achievement goals have been linked to achievement in various educational settings. The present work explored day-to-day variations in achievement goals (mastery, performance-approach, performance-avoidance) and their associations with daily experiences of academic success and failure. Ambulatory assessment data from 108 students in Grade 5 were collected, with daily assessments of achievement goals in the morning and end-of-day reports of academic success and failure. Dynamic structural equation models revealed reciprocal within-person effects between mastery goals and academic success. Academic success was further associated with higher mastery and performance-approach goals in the next morning. Academic failure was linked to both performance goals, though this association was not robust in all sensitivity analyses. Higher average daily academic success and lower average academic failure were linked to better academic achievement one year later. Findings suggest meaningful within-person dynamics among goals and daily academic success and failure. 相似文献
50.
中国股市投资组合规模与风险关系的实证研究 总被引:4,自引:1,他引:4
本文采用简单随机等权有放回抽样方法,以双周收益率为指标,以沪深两市所有A股为样本股,对1994年、1995年、1996年、1997年、1998年、1999年及1994年到1999年各个样本期间组合规模与风险关系进行实证研究,得出结论:为了有效地减少风险,提高收益,股票组合的规模以10-20只股票为宜。 相似文献