介绍一种水轮机调速器残压测频信号预处理电路

在水轮机调速器系统中残压测频是主要环节，其测频的稳定性和精度直接反映调速器能否快速响应，并稳定运行。高次谐波的引入是造成调速器残压测频不稳定的主要原因，因此需要设计一个新的残压测频电路，彻底消除高次谐波的影响。     

黄河上游地区云层特征与降水关系的分析

应用１９９２－１９９６年４－９月黄河上游河曲段部分气象站逐日０２、０８、１４、２０点云量和云状、２０－０８点、０８－２０点降水资料,计算分析了４－９月黄河上游河曲地区主要降水云层。对流云和层状层的云层特征,出现效率、地理分布及其与降水的关系。结果表明,黄河上游河曲地区４－９月层状云出现频率的１５％,其≥０．１ｍｍ降水率的５０％,地理分布以久治为高值中心,由南向北呈递减趋势。对流云出现频率的６０％、     

Exploring student hand-raising across two school subjects using mixed methods: An investigation of an everyday classroom behavior from a motivational perspective

Student hand-raising is an everyday behavior in classroom interactions with teachers. This research presents two studies that examine the variance in hand-raising and its relation to student motivation in two school subjects, Mathematics and Language Arts. Student hand-raising is introduced as an indicator of behavioral engagement. Study 1 investigated N = 397 high school students in 20 classrooms during a videotaped lesson in each subject. Multilevel regression analysis suggests that student motivation accounts for significant variance in hand-raising. The results show subject-specific differences: Student self-concept predicts hand-raising in Mathematics, while students' situational interest predicts their hand-raising in Language Arts. Students’ externally regulated motivation is predictive across both subjects. In Study 2, N = 14 high school students were interviewed about their hand-raising behavior. The results validate and extend the findings from Study 1. Finally, this research emphasizes the importance of fostering student hand-raising and discusses the implications for future research.     

基于FPGA的频率计电路设计

本文介绍了数字频率计设计的基本原理,对频率计所采用各种硬件除法进行了比较,提出了倍频计数法测量数字高频的实现方案,并给出了频率计设计的硬件电路原理和软件实现,结果表明这种方法实现了频率计的高速和高精度。     

Understanding users’ behaviors regarding supply chain technology: Determinants impacting the adoption and implementation of RFID technology in South Korea

Radio Frequency Identification (RFID), once a niche technology, is rapidly gaining the attention of retailers as a key enabler in their supply chain. As RFID moves into the mainstream, it is poised to replace the standard barcode as the technology that identifies and tracks products throughout the supply chain. In an attempt to gain competitive advantages, some retailers have begun the transition to RFID while others have been reluctant to embrace it. This study investigates South Korean retailers to identify key organizational characteristics that positively drive the evaluation of RFID. Further, this study assesses the impact one's evaluation has on the adoption and integration of RFID within their respective firm. Results from 278 adopting organizations show organizational needs (Ubiquity and Performance Gaps), perceived factors (Benefits and Cost Savings), and organizational readiness (Financial Resources and Technological Knowledge) have a significant influence on RFID Evaluation; and evaluation impacts its adoption, and integration.     

一种基于混沌加密的视频水印方法

利用二维混沌流加密技术加密有意义的二进制图像,获得水印数据,以提高视频水印的安全性。水印嵌入过程中,水印被嵌入到随机选择的视频帧的离散余弦变换系数里。在鲁棒性和帧平均攻击实验后,大部分水印可以通过水印检测提取算法进行提取和识别。实验结果表明,这种视频水印方法具有一定的安全性、隐蔽性和鲁棒性。     

基于互信息量的视频关键帧提取算法

关键帧提取技术是基于内容检索和视频分析的基础。关键帧的使用减少了视频索引的数据量,同时也为视频摘要和检索提供了一个组织框架。首先介绍了目前关键帧提取技术,然后提出了一种基于互信息量的关键帧提取方法,该算法以帧间互信息量来衡量两帧图像内容的相似性,可以对具体镜头按其特点自动提取出一个或多个关键帧。实验结果表明这种方法可以较好地概括视频内容。     

浅析视频技术的发展和应用

当前视频技术发展迅速且应用广泛,然而视频格式的不统一、编码技术的多样性却给视频的创建和使用带来了诸多不便。本文就各类视频文件的特点、应用和转换方式进行了深入的分析和探讨。     

神经网络在视频检索中的应用

随着计算机技术的发展,视频数据的容量以几何级数增长。如何在海量视频数据库中快速地检索到所需视频成为热门的研究课题。本文提出了一种基于反馈式神经网络的视频检索算法,对视频进行基于内容的分析和检索。实验表明用该方法检索的准确度比用基于关键帧的视频检索方法平均提高4%以上。     

典型实验教学视频案例制作的教学设计——以“乙酰水杨酸的制备”为例

典型实验教学视频案例为提高高校实验教学效果,促进实验教学改革起到重要推动作用。针对实验教学视频案例的制作,文章从教学设计的视角,以个案研究的方法,对典型实验教学视频案例的概念特点以及如何应用教学设计做了详细介绍。