基于MEMS技术的微型流量传感器的研究进展

流量测量是工业生产和科研工作的重要的检测参数.近年来,随着对微电子机械系统(MEMS)的深入研究和取得的进展,传统的工业和流体力学研究的流量传感器向高集成度,微型化,高精度,高可靠性方向发展,同时生命科学的发展大大促进了用于微流体,生物学、医学、卫生、食物等学科研究新型微型流量传感器的研究开发, 微型流量传感器已成为MEMS的重要研究方向.本文对基于MEMS技术的流量传感器技术的原理、分类作了简要介绍,归纳和评述了各种基于MEMS技术的流量传感器(热式型,差压型,升力型,流体振动型, 科里奥利型及仿生型微型流量传感器等)的生产工艺和应用特点,并对基于MEMS技术的微型流量传感器的校正方法做了总结归纳.介绍了国内在微型流量传感器方面的研制工作.最后总结归纳出基于MEMS技术的流量传感器发展不同阶段并阐述了各个阶段的发展特点,并对基于MEMS技术的流量传感器新的发展趋势进行了展望.      

粒子图像测速技术研究进展

粒子图像测速技术(PIV)作为一种全新的无扰、瞬态、全场速度测量方法,在流体力学及空气动力学研究领域具有极高的学术意义和实用价值.本文对PIV技术的原理、分类作了简要地介绍,详细归纳和评述了现有的各种速度信息的提取方法,并对拓扑图论、神经网络、遗传算法、模糊聚类等新技术在PIV中的应用以及三维PIV技术、两相流PIV测试技术进行了介绍.指出当前PIV技术除了向三维和多相流方向发展外,如何提高PIV的测量精度以及缩短计算时间仍然是目前研究的主要目标.PIV技术随着计算机技术、激光技术和CCD性能的发展,必将取得更大的发展与突破      

The construction fo meanings for trend in active graphing

The development of increased and accessible computing power has been a major agent in the current emphasis placed upon the presentation of data in graphical form as a means of informing or persuading. However research in Science and Mathematics Education has shown that skills in the interpretation and production of graphs are relatively difficult for Secondary school pupils. Exploratory studies have suggested that the use of spreadsheets might have the potential to change fundamentally how children learn graphing skills. We describe research using a pedagogic strategy developed during this exploratory work, which we call Active Graphing, in which access to spread sheets allows graphs to be used as analytic tools within practical experiments. Through a study of pairs of 8 and 9 year old pupils working on such tasks, we have been able to identify aspects of their interaction with the experiment itself, the data collected and the graphs, and so trace the emergence of meanings for trend. This revised version was published online in July 2006 with corrections to the Cover Date.     

到主要热点城市的英、法、德、游客流的数值分析

讨论了全国主要热点旅游城市中英法德游客人数占当年来华英法德总人数的比例值的变化,使用一阶常系数线性差分方程构造了其动态模式。由于加权平均数的使用,加大了近期旅游变化的信息。     

长江三角洲气温的长期变化

本文用1873—1985年上海平均气温资料研究长江三角洲气温长期变化的规律.结果表明:本地区气温长期变化曲线呈波动形式.近三十余年中出现的年,季平均气温最低值未曾低于前八十年所曾出现过的最低值,而最高值却有与以往出现过的最高值相当的.取一百十三年平均气温作基准,则由累积距平曲线可见近五十年上海气温以正距平即暖年占优势.文中还讨论了气温年波长期变化的特征.     

A simple method suitable to test the ultimate biodegradability of environmentally degradable polymers

A straightforward experimental set-up derived from the Biometer Flask previously utilized for experiments of pesticides biodegradation, has been adopted for testing the ultimate biodegradability of natural, synthetic and semi-synthetic polymeric materials on solid substrates such as soil and mature compost. The use of these whole substrates as incubation media in respirometric experiments, may negatively affect the accuracy of the test due to the large amount of carbon dioxide developed from the blanks, especially in the presence of specimen degrading at low or moderate rates. In the present test procedure soil and compost samples are diluted with perlite, a naturally occurring inert aluminum silicate widely utilized in horticultural applications, in order to ensure optimal conditions for the microbial growth while reducing the carbon dioxide emissions from the blanks. The results so far reported clearly indicate that the adopted procedure is extremely valuable and versatile for the appreciation of even subtle differences in the biodegradation rate of different polymeric materials, as well as for long-term degradation experiments.     

210Po、210Bi和210Pb测试技术研究进展与现状

铀系核素210Po、210Bi和210Pb的测试在铀矿地质勘查与核废物安全处置研究、沉积年代学与同位素地球化学研究、大气环境学与辐射卫生学研究等诸多领域具有重要意义。重点总结了近些年来210Pb、210Bi和210Po三核素各种测试技术的研究进展与现状,评述了存在的主要问题及未来发展趋势。