水平支座上独立式刚性块的摆动模型（英文）

目的:本研究集中探讨水平支座上独立放置简单叠合的双刚性块的动力学行为,旨在通过构建并求解合适的动力学数值模型以助于设计可广泛适用于博物馆、实验室和医院的保护小型艺术品或装置的隔振系统。创新点:1.研究对象为两个叠合在一起的刚性块,较以往同类问题中的单一刚性块,更具现实意义;2.同时研究了刚性块的摆动和滑动两类运动模式。方法:1.基于达朗贝尔原理构建摆动控制方程,分析单刚体情形下的摆动并利用数值手段描述其滑动状态;2.在分析单刚体的基础上构建双刚体控制方程组并对其进行数值求解。结论:1.通过研究大理石雕塑置于蹲式刚性基底上且基底独立放置在移动地面上的情形发现,相比于滑动,雕塑自身的摆动是造成其损坏的主要原因;2.在某些情况下,刚体表面延迟的存在可以避免细长刚性块的翻转,尤其是对于那些细长的摇摆块体以及上部块体质量增加的情形;3.本文提出的数值分析可以成为优化简易隔振系统的一个有效工具。     

Computerized Adaptive Testing in Early Education: Exploring the Impact of Item Position Effects on Ability Estimation

Studies have shown that item difficulty can vary significantly based on the context of an item within a test form. In particular, item position may be associated with practice and fatigue effects that influence item parameter estimation. The purpose of this research was to examine the relevance of item position specifically for assessments used in early education, an area of testing that has received relatively limited psychometric attention. In an initial study, multilevel item response models fit to data from an early literacy measure revealed statistically significant increases in difficulty for items appearing later in a 20‐item form. The estimated linear change in logits for an increase of 1 in position was .024, resulting in a predicted change of .46 logits for a shift from the beginning to the end of the form. A subsequent simulation study examined impacts of item position effects on person ability estimation within computerized adaptive testing. Implications and recommendations for practice are discussed.     

Living at the Border: between multiculturality,complexity and action research

The author looks into the phases of her personal experience in order to present the difficulties as well as the richness of ‘living at the border’ and of building bridges between different worlds. The prevailing Anglo-Saxon culture, above all in the world of research, obliges those who do not belong to this culture to undergo a form of tension between adaptation to language rules and ways of thinking that are foreign to them, and the need to maintain cultural and personal differences while trying to communicate. The experience of ‘contagion’ between ideas and ways of representing the world, that was seen within the Environment and School Initiatives Project (ENSI) project and that the author had the opportunity to share with John Elliott, shows the possibilities offered by these encounters. Issues such as those of the complexity and quality of learning have interweaved with those of action research and evaluation, and have crossed and enriched the values and cultures of which we were implicitly and explicitly the bearers. In the final section the author makes an attempt to illustrate the risks of today's globalisation and the tendency to eliminate borders, viewed as obstacles to individual freedom, for a kind of equalisation which, by eliminating the differences, also eliminates the possibility of development and of creativity.     

Teacher subcultures of democratic practice amidst the oppression of educational reform

Teachers’ voices explore and document what is at stake when they are excluded from power-brokering conversations that mandate how teachers practice and model democracy in classrooms. Case study vignettes, interviews, classroom observations, and reflections of teachers in urban and suburban schools reveal four significant teacher subcultures of democratic practice: a subculture of compliance, a subculture of noncompliance, a subculture of subversion, and a subculture of democratic inquiry and practice. Analyses reveal that each subculture poses significant stakes for teachers, preservice teachers, the teaching profession, pupils, and society writ large.     

Working with artefacts: gestures, drawings and speech in the construction of the mathematical meaning of the visual pyramid

This paper reports a part of a study on the construction of mathematical meanings in terms of development of semiotic systems (gestures, speech in oral and written form, drawings) in a Vygotskian framework, where artefacts are used as tools of semiotic mediation. It describes a teaching experiment on perspective drawing at primary school (fourth to fifth grade classes), starting from a concrete experience with a Dürer’s glass to the interpretation of a new artefact. We analyse the long term process of appropriation of the mathematical model of perspective drawing (visual pyramid) through the development of gestures, speech and drawings under the teacher’s guidance.

Modelling the joint impact of R&D and ICT on productivity: A frontier analysis approach

This study explores the channels through which technological investments affect productivity performance of industrialized economies. Using a Stochastic Frontier Model (SFM) we estimate the productivity effects of R&D and ICT for a large sample of OECD industries between 1973 and 2007, identifying four channels of transmission: input accumulation, technological change, technical efficiency and spillovers. Our results show that ICT has been particularly effective in reducing production inefficiency and in generating inter-industry spillovers, while R&D has raised the rate of technical change and favoured knowledge spillovers within sectors. We also quantify the contribution of technological investments to output and total factor productivity growth documenting that R&D and ICT accounted for almost 95% of productivity growth in the OECD area.     

Context and quantitative dimension of social conventional transgressions: Is it more serious at home or at school?

The aim of this experiment was to know whether the same transgressions were judged of different seriousness depending on their context of occurrence, and whether subjects’ judgements varied according to age. Sixty subjects participated in the experiment, 20 4-year-olds, 20 8-year-olds, and 20 adults. Four cases of transgression of social conventional rules were examined. Each transgression occurred in four contexts. Subjects compared the contexts of each transgression in pairs in all combinations. For each age group, data were analyzed by means of Kruskal’s scaling in order to rank the contexts of each transgression, and by means of correspondence analysis to relate transgressions and contexts with each other. Results show that children of both ages are quite consistent in their ranking of contexts. They differ from adults who, instead, consider transgressions to be more context-specific. Results are discussed for their theoretical value and in relation to the concept of context.