Complexities of digital technology use and the teaching and learning of function

Many argue that digital technologies have the potential to enhance the teaching and learning of mathematics. However, the availability of technology is not sufficient to realise this potential. The study reported takes a detailed approach to investigate the utility of the particular offerings of the available technologies in the teaching and learning of a specific area of mathematics, functions. Sixteen affordances identified in the data are described. The complexity of the process involved in resolving a situation where particular affordances would be useful so as they are perceived and enacted is detailed. Finally, a grounded theory framework arising from the data analysis from this study that can be used to explain, predict and guide action in other digital environments is presented.     

A 3-D motion tracing system in High School Physics teaching

Abstract This article presents a study of a large scale incorporation of one data acquisitionsystem into physics teaching in Israel. By 1994 about 30% of the schools throughout the country used the V-scope, a 3-D multibody motion tracing system, in their lab programme. The views and reactions of post-training teachers, experienced teachers and students on various aspects of using the system are described, analysed and compared.     

焊接领域中 AutoCAD的二次开发

应用AutoCAD已有的二次开发工具:AutoLISP、块和形定义及菜单开发对CAD在焊接领域应用进行了开发与定制。     

An exploratory study of adolescent's perceptions of the Web

Abstract The purpose of this exploratory study was to investigate the influence of two individual characteristics (Web experience and academic focus) of adolescents on the Web perception, using off-line questionnaires (a Lickert response scale) constituted on the basis of a series of interviews. Questions concerned: perceptions about the nature of information found in the Web; 'strategies' of access to the interesting Internet sites and the reliability of different information resources (libraries, television, Web, etc.). Results lead to the assumption that adolescents with high Web experience became more critical, less confident and less enthusiastic than adolescents with low Web experience and that, in some dimensions, perceptions of literature students are different to those of science students. Even if some interesting results were obtained, further research is needed to explore users' perceptions related to individuals' characteristics and to determine the generalisability of the influences identified in this exploratory study.     

Why is science difficult to learn? Things are seldom what they seem

Abstract The difficulties of learning science are related to the nature of science itself and to the methods by which science is customarily taught without regard to what is known about children's learning. An information processing model is proposed to guide thinking and research in this area.     

Secondary ion emission from Ti and Si targets induced by medium energy Ar ion bombardment - Experiment and computer simulation

The paper presents experimental results of secondary ion energy distributions obtained for Ti and Si targets bombarded by 20-30 keV monoisotope Ar⁺ ion beam. The influence of the extraction voltages between target and a slit of the electrostatic energy analyzer entrance on the energy distributions of secondary ions was investigated. After optimization of the secondary ion extraction system, the mass spectra of secondary ions were also measured. The investigations were done using recently built experimental system. Experimental data are compared with the computer simulation results obtained using TRQR and SATVAL codes.     

Autolisp在开发V画面体视图自生成系统中的应用

介绍了近年来体视投影技术的应用及发展，并提出了用AutoCAD的内嵌开发工具Autolisp语言结合Visualisp中的对话框控制语言DCL来开发体视图自动生成系统的新思路．根据V画面体视投影原理，推导出了V画面体视变换矩阵．给出了该系统的程序流程框图及相应的功能模块．并将该系统的界面和基本功能进行了展示，从而为体视自生成技术的研究开辟了新的道路．     

分析再热器超温爆漏与水冷壁结焦控制量的关系

文章介绍了宝钢自备电厂在改善锅炉燃烧工况，控制锅炉水冷壁结焦所采取的技术措施，分析了锅炉水冷壁结焦量与锅炉二次再热器烟气出口平均温度的关系，为解决锅炉水冷壁结焦所引发的二次再热器超温爆漏问题提供了依据。     

Data-logging: effects on practical science

Abstract This paper describes an investigation into the processes and effects of using electronic data-logging in practical science. A pilot study of classical laboratory work in schools was compared with similar tasks performed with data-logging systems. A more detailed exploration of pupils' performance was then conducted through an extensive series of observations in a range of secondary schools. The results reinforce previous indications of the potential benefits of data-logging, but such benefits must be viewed in the curriculum context of the type of measurement activity and the pedagogical context of teaching and learning objectives. The paper concludes with a discussion of the latter issues.     

Microstructural transformations of heat affected zones in duplex steel welded joints

The influence of the welding thermal conditions exemplified by heat input and heat treatment after welding on the structure of the heat affected zone (HAZ) UNS S31803 has been analysed. The post weld treatment was used to create the precisely defined thermal conditions for the decomposition of primary phases in the HAZ, by a multi-layer welding thermal cycle stimulation. Detailed analyses of the microstructure and chemical composition of the phases in the different post welded conditions were performed by scanning electron microscopy (SEM) combined with energy dispersive spectrometry (EDS) and transmission electron microscopy (TEM). Three types of secondary precipitates have been observed: secondary austenite (γ₂), carbides: M₂₃C₆ and M₇C₃. The dependence of the secondary austenite volume fraction and morphology in the HAZ on thermal cycle have been interpreted. The eutectoid decomposition of the primary phases in the analysed thermal conditions was confirmed.