有源电子式互感器实现准无源化的改进

“自励源”是一种日臻完善的电子式互感器高压侧自供电技术,它可以实现有源电子式互感器的“准无源化”,早期投运且依靠激光送能方式在线运行的电子式互感器,普遍存在寿命周期短、运行不稳定等弊端.笔者介绍了将激光送能改进为全自励源运行的原理和方法,记述了对于110 kV整站技术改进的全过程.经过改进的电子式电流互感器简化了系统结...     

双包层EYDFA增益钳制效果的理论研究

基于速率方程的离散算法,实现了环形腔控制方案下,双包层EYDFA增益钳制的分析,研究了单、多信道情况下增益、噪声指数钳制的效果。结果表明：对于单信道EYDFA,随着衰减器衰减系数的增大,EYDFA的增益钳制范围增大,但信号增益钳制的幅度减小,且信号噪声指数增大;对于多信道EYDFA,只要激光谐振不被破坏,各信道增益都能得到有效钳制。     

光电对抗平台高精度平稳跟踪技术

针对某光电对抗平台跟踪精度高、跟踪平稳连续的要求,提出了基于PI-P调节器的复合控制技术,具有结构简单、抗负载扰动能力强、控制平稳等特点,保证了系统的高精度跟踪;通过先对视频跟踪器数据进行合理性检验,然后与外部引导数据进行数据融合的方法,剔除干扰,提高对机动目标位置预测的可信度和准确度,保证目标跟踪的连续性和平稳性。实验结果表明,该方法满足系统高精度、平稳连续跟踪的要求,在保精度角速度20(°)/s,保精度角加速精度25(°)/s2时跟踪最大误差小于2′,该系统具有广泛的适用性。     

基于结构网格的增升构型失速特性大规模并行数值模拟

针对民机增升构型失速特性的数值模拟,我们基于贪婪负载平衡算法的剖分工具对多块结构网格进行区域分割,在某新型超级计算机系统上完成求解软件的移植、优化和测试,采用 2 亿量级的计算网格开展大规模并行计算研究,测试完成了万核级负载平衡的网格区域分割,实现了增升构型失速特性的 4 096 核数并行计算,并行效率达到 50% 以上,提高了工程应用中对复杂流动现象的数值模拟能力。数值模拟结果加深了对增升构型失速流动机理的理解,可以为增升装置设计优化提供有意义的参考依据。     

利用CAD二次开发使生产配套报表自动生成

针对手工编制生产配套报表效率低、差错多的问题,分析企业现行产品图样设计规范和生产报表编制规则;充分利用现有CAD软件的报表模块和程序接口,经过二次开发实现用CAD软件自动生成汇总生产配套报表。     

数字闭环光纤电流传感器暂态特性仿真研究

数字闭环光纤电流传感器暂态特性主要包含频率响应与阶跃响应,对于电力系统的继电保护控制、故障录波等应用领域至关重要。在工程应用中,传统的测试方法由于其测试系统复杂、测试电流信号小等问题,不利于评估光纤电流传感器的暂态特性。利用数字闭环光纤电流传感器的闭环控制机理,提出一种在数字闭环光纤电流传感器反馈回路中添加相位调制激励的方法。首先,分析数字闭环光纤电流传感器的相位调制原理,通过建立数学模型验证相位调制激励的等效性;其次,根据数字闭环光纤电流传感器闭环控制算法,提出频率响应与阶跃响应的调制激励产生方法;最后,利用现有数字闭环光纤电流传感器产品平台完成频率响应与阶跃响应的仿真与测试。结果表明:采用相位调制激励的仿真数据与试验数据最大误差为0.12%,该调制激励方法不需要搭建复杂的测试系统,在现有硬件平台中即可实现不同电流信号的仿真测试。     

The impact of individual differences on the equivalence of computer-based and paper-and-pencil educational assessments

Computer-based assessment (CBA) is yet to have a significant impact on high-stakes educational assessment, but the equivalence between CBA and paper-and-pencil (P&P) test scores will become a central concern in education as CBA increases. It is argued that as CBA and P&P tests provide test takers with qualitatively different experiences, the impact of individual differences on the testing experience, and so statistical equivalence of scores, needs to be considered. As studies of score equivalence have largely ignored individual differences such as computer experience, computer anxiety and computer attitudes, the purpose of this paper is to highlight the potential effects of these. It is concluded that each of these areas is of significance to the study of equivalence and that the often inconsistent findings result from the rapid changes in exposure to technology.     

级联双包层铒镱共掺光纤放大链路的增益瞬态及控制研究

基于速率方程的"离散"算法,实现了对双包层Er3+/Yb3+共掺光纤放大器级联链路功率瞬态及控制效果的分析。研究了级联链路中功率漂移与级联放大器数量的关系以及反馈控制抑制增益瞬态的效果。结果表明:随着级联放大器数量的增多,线性区功率漂移的斜率明显增大,达到峰值的时间越来越短,且漂移功率峰值达到5.1dB;反馈控制能有效抑制放大链路的功率漂移,但随着级联放大器数量的增多,功率漂移的峰值会逐渐增大。     

光盘信息符统计特性的激光散斑测试

采用激光散斑的方法研究了CD光盘的刻录质量.由于标志光盘信息符的凹凸结构导致了光盘表面微结构的光学粗糙性,光盘不同区域被激光照射后在测量空间形成散斑图像,通过分析光盘不同区域产生的散斑图的统计相关性及对比度值的变化,对光盘的刻录质量进行了定性研究.结果显示,刻录质量好的光盘,其不同区域的散斑相关性好,散斑对比度值高且起...     

The development and validation of an instrument for assessing college students' perceptions of faculty knowledge in technology-supported class environments

Research in the area of educational technology has argued that the technological pedagogical content knowledge of faculty is crucial to addressing the challenge of teaching in higher education in the digital age, which is characterized by the common use of instructional technology in college classrooms and the ubiquitous presence of computing on college campuses. We developed and validated an instrument for assessing students' perceptions of faculty knowledge (SPFK) in technology-supported classroom environments. A total of 50 items in 4 constructs with 9 items in subject matter knowledge (SMK), 11 items in technological knowledge (TK), 6 items in knowledge of students' understanding (KSU), and 24 items in technological pedagogical content knowledge (TPACK) were developed for the instrument. The construct validity of this instrument was examined through confirmatory factor analysis. After checking the construct structure of the instrument, the multidimensional version of the rating scale model (MRSM) was used to analyze item response data. Results showed that after the elimination of item 17, the 49-item instrument for assessing college students' perceptions of faculty knowledge was validated in the current study. The reliability for each subscale of this instrument was found to be satisfactory when analyzing data with the MRSM model. Discussion of results and recommendations for future research are also provided.