高压断路器三相永磁无刷直流电机机构控制算法研究

针对高压断路器三相永磁无刷直流电机机构,研究了不同控制策略下电机操动机构的运动特性.考虑高压断路器的分、合闸操作过程,建立了永磁无刷直流电机操动机构运动控制系统的仿真模型,采用数字式双闲环控制,内环为电流环,采用PI控制,外环为速度环,基于传统PID控制器、单神经元PID控制两种不同控制策略控制.通过对伺服控制系统的仿真分析得到了电机操动机构速度跟踪控制特性.结果表明,单神经元PID控制器能够较好的实现触头速度的跟踪控制,使其按理想运动特性曲线运动,是一种较理想、有效的控制方法.     

A hierarchical Path Computation Element (PCE)-based k-random-paths routing algorithm in multi-domain WDM networks

We propose an inter-domain routing algorithm for multi-domain wavelength-division multiplexing (WDM) mesh networks. On the basis of the hierarchical Path Computation Element (PCE) architecture, the proposed algorithm introduces a k random path strategy in the parent PCE to adjust the algorithm optimization level. Simulation results indicate that the proposed algorithm outperforms previous schemes in terms of blocking probability and resource utilization, while preventing the increase in PCEP signaling overhead.     

The influence of textese on adolescents’ perceptions of text message writers

Text messages are characterised by a casual language style, ‘textese’ (e.g., c u on thurs). This study investigated adolescents’ perceptions of the use of different levels of textese in digital messages which varied in their intended recipient (friend, teacher). Grade 8 students in Australia (N = 90, aged 13–14 years) each read six text messages purportedly written by a fellow student, and rated the extent to which they agreed (on a 7-point Likert scale) that the message writer was intelligent, paid attention to detail, used an appropriate writing style, and was friendly. Overall, participants rated message senders most favourably on all measures when they used no textese, and least favourably when they used high levels of textese. This pattern was even stronger when messages were addressed to teachers rather than same-aged friends. The findings suggest that adolescents are sensitive to both writing style and recipient when considering digital messages.     

电视栏目剧故事叙述的传统文化诉求及其社会功能

电视栏目剧是民间自导自演的电视短剧。编导在创作故事情节、刻画人物过程中,自然地融合了对中国传统政治、文化、教育及法律观念、国民性格的理解,剧情也集中地体现了中华民族的孝文化和中庸的传统思想。因此电视栏目剧的故事叙述具有教育和娱乐的社会功能,是我国现阶段社会核心价值体系建立的有效途径之一。     

网络环境下智能化学习模式构建与实践研究

随着计算机技术和网络技术的飞速发展,以及各种移动设备的应用与普及,网络环境下的学习方式已经成为新时期现代化教学方式发展的新方式.但目前网络环境下的学习方式还存在如上课形式单一、学习资源不足、学生自主学习能力弱、课堂互动较少、各种教学活动不易于控制等问题,那么就急需构建网络环境下新的学习方式.将智能化融入教学过程中不仅能...     

InGaN基高压LED和传统大功率LED的发光效率比较

主要从三个不同角度探究并分析了基于In Ga N材料的高压LED的发光效率优于传统大功率LED的原因。为了保证实验结论的可靠性,文中所采用的实验样品具有相同的芯片尺寸和材料以及相同的封装结构。经过大量的实验证明,更均匀的电流分布和小芯片间隙的出光,使得高压LED的发光效率优于传统大功率LED。结果显示,在相同的1 W输入功率下,高压LED的发光效率比传统大功率LED高大约4.5%。     

基于AT波形重构方法的逆变技术研究

在中高压变频驱动系统中,通常采用多电平逆变技术,以降低逆变电压的谐波.本文采用波形重构方法,在介绍其基本工作原理的基础上,详细分析了此逆变器的导电制,并给出了输出电压总谐波畸变率与其参数的关系,并将该逆变器与几种常见的逆变器从直流电源利用率、总谐波畸变率等方面进行了比较分析.仿真实验研究结果表明,采用开绕组异步电机实现的二重化,同样具有较好的性能.     

MEMS划片技术的现状与技术革新

MEMS独特的结构和特性,给划片工艺带来了巨大的挑战.介绍了传统砂轮划片技术在MEMS芯片生产中的局限性,指出了隐形激光划片技术的优越性,综述了激光划片技术在MEMS划片中的应用,对几种较成熟的先进激光划片技术进行了比较,对各自的工作原理、特点、工序作了重点阐述,并对MEMS划片技术的发展前景作了展望.     

Study of Relation between EFL Students' Cognitive Style and Pragmatic Competence

Individual difference is one of the important factors affecting the success of learning English as foreign language (EFL). However, very little research has dabbled in the correlation between pragmatic competence and cognitive styles among college students. Two questionnaires (the embedded figure test and the pragmatic competence test) were designed and used to conduct our study among seniors with non-English majors from key universities. The data was analyzed with SPSS 21.0 and results showed that pragmatic competence of the subjects was much lower than expected. Besides, there was a significant and positive correlation between field dependent (FD) cognitive style and inter-language pragmatic competence while no significant correlation was found with field independent (FI). A regression model was also formulated to obtain more specific information. Lastly, some practical advice is offered for teachers to boost students' pragmatic competence in the future with FD/FI cognitive styles into proper consideration.     

应用高新技术改造传统产业 实现绿色环保和高效节能

文中分析高压变频器的应用前景、技术特征、关键技术和应用案例,说明了在传统产业中采用高压变频器进行技术改造,不仅降低了能耗,平均节电率超过24%,还带来了系统应用的便利性,实现了传统产业的绿色环保和高效节能。还介绍了新能源产业中的光伏逆变器产品的原理和应用情况。