Steam as coolant and lubricant in turning of metal matrix composites

Green cutting has become focus of attention in ecological and environmental protection. Steam is cheap, poilution-free and eco-friendly, and then is a good and economical coolant and lubricant. Steam generator and steam feeding system were developed to generate and feed steam. Comparative experiments were carried out in cutting AA6061-15 vol.% SiC （25 p.m particle size）, with cubic boron nitride （CBN） insert KB-90 grade under the conditions of compressed air, oil water emulsion, steam as coolant and lubricant, and dry cutting, respectively. The experimental results show that, with steam as coolant and lubricant, gradual reduction in the cutting force, friction coefficient, surface roughness and cutting temperature values were observed. Further, there was reduction in built up edge formation. It is proved that use of water steam as coolant and lubricant is environmentally friendly.     

中学化学实验绿色化设计思想初探

绿色化学作为一门全新的课程，是人类实现可持续发展的重要保证，化学作为一门以实验为基础的科学更应该贯彻绿色化学、绿色实验这一理念。针对国内目前关于中学化学实验绿色化设计从思想体系角度进行研究尚属空白的现状．本文分析了中学化学实验绿色化教育的现状并运用绿色化学理念对中学化学实验绿色化设计思想体系进行了较为详尽的阐述。     

经济欠发达地区民办高等教育发展模式研究

经济发达地区和经济不发达地区对民办高校发展模式的选择是不同的。目前在我国经济欠发达地区,民办高等教育的发展自觉或不自觉地采取了“来料加工”和“自给外销”模式。这是当前经济欠发达地区摆脱经济发展水平制约的最佳模式。从短期看,这些发展模式有效地帮助了经济欠发达地区民办高校挣脱经济瓶颈,实现快速发展。但从长期看,人才外流会大大降低当地人口素质,从而制约经济欠发达地区产业结构高级化的进程,并进一步制约高等教育的发展。     

基于EDA技术的多功能等精度数字频率计的设计

在对三种测频方法进行分析的基础上,介绍了基于EDA技术的等精度测频原理.给出采用AT89C51实现控制并通过FPGA来设计多功能等精度数字频率计的具体方法.该频率计可以兼顾频率计对速度、资源和测频精度等各方面的优化需求.     

TIFRAC, India’s first computer — A retrospective

To be associated with an important and challenging activity that is being carried out for the first time in the country is a truly memorable and satisfying, even if somewhat disquieting experience. I was privileged enough to have this opportunity when I was involved in the design and implementation of India’s first computer. TIFRAC (Tata Institute of Fundamental Research Automatic Calculator) — so was it named by Jawaharlal Nehru when it was formally commissioned in 1960 — was a truly a unique computer. Some of the features of this machine are described later in this article. It is also my intention in this article to convey some of the excitement, adventure and sense of accomplishment that the successful completion of this exercise brought to the design team.     

Mathematics teaching during the early years in Hong Kong: a reflection of constructivism with Chinese characteristics?

This paper characterizes early mathematics instruction in Hong Kong. The teaching of addition in three pre‐primary and three lower primary schools was observed and nine teachers were interviewed about their beliefs about early mathematics teaching. A child‐centered, play‐based approach was evident but teachers emphasized discipline, diligence and academic success. Observations also revealed practices reflective of both constructivist and instructivist pedagogies. Results from interviews suggest that teachers' traditional cultural beliefs about instruction were challenged by western ideologies introduced in continuing professional development courses and by notions promulgated by the educational reforms. Both consistencies and inconsistencies between teachers' beliefs and practices were identified. Implications of the findings are discussed.     

独立学院大学英语目标定位及实现途径--以温州大学城市学院为例

大学英语作为各高校都开设的一门公共基础课程,历来受到各界的重视。而对于独立学院而言,大学英语课程体系的准确定位,关系到整个课程体系的发展方向。本文以温州大学城市学院为例,旨在探讨在当前大学英语转型的新形势下,独立学院应如何确定大学英语的目标定位,进而对此定位的实现途径从课程体系设置、教学模式方法选择和评估手段采用等方面进行讨论。     

论技术类科技期刊的品牌创建——《中国南方果树》33年办刊实践与探索

在总结中国南方果树杂志社33年办刊工作实践的基础上,从刊物定位、编读关系、刊物质量、刊物特色、刊物经营、刊物文化等6个方面论述技术类期刊的品牌创建.     

电路综合实验改进模式的探索与实现

电路综合实验是电子信息类专业必修的一门专业基础实验课,在课程衔接上起着承上启下的重要作用.分析了通信专业学生不同学习阶段的专业知识层次特点,提出用模块化的设计理念,并以此理念为指导,以数字基带传输系统为例,利用FPGA(field programmable gate array)技术,将软件仿真和硬件结合起来,解决了数字基带传输系统设计环节中几个关键的技术问题,开发了各个模块级实验以及整个系统级实验,实现了不同阶段课程内容的有效衔接和融合,解决了学生知识背景低和实验内容层次高的矛盾.     

透析听毛细胞动作电位的形成原理——从2020年山东卷一道题谈起

本文通过对山东省2020年普通高中学业水平等级考试的一道疑似“错题”进行“拨乱反正”,解答部分师生对该题涉及的听毛细胞动作电位形成原理的疑惑。