原子量基准的设定及其教育价值

从以氢为基准到以氧为基准,再到以碳为基准,原子量基准的设定与化学学科的发展紧密相关。运用原子量基准的设定史实,可以帮助学生解决相关的困惑,学习其中蕴含的思想方法和科学态度,认识科学的本质,充分发挥史实的教育价值。     

Expanding scissor-based UGV for large obstacles climbing

This research proposes a new extendable platform for an unmanned ground vehicle to overcome the obstacle climbing issue. The new platform is basically established on scissor mechanism principles which have been innovated to achieve long and rigid displacement. A couple of scissor mechanisms are embedded in the rover platform adjusting the mass center of rover respect to the rear and front wheels. Accordingly, it yields geometric control of the contact forces, which can simultaneously reduce the slip of the wheels and increase the performance of the obstacle climbing up. To demonstrate the performance of the proposed platform, the 3D kinematics is derived. Subsequently, the stick-slip Euler-Lagrange dynamics is derived and a three-level controller including the torque optimization is implemented to simulate the rover facing obstacles. Finally, without any hardware prototyping, the extendable rover is simulated and compared with a typical fixed-geometry rover to show the enhancement of the climbing ability by using the proposed concept. Moreover, controlling the normal contact forces of the wheels yields the slip reduction, which subsequently, increases the traction force.     

Design and development of planar reconfigurable motion generators

This article presents the concept of a new class of mechanical devices for multi-phase motion generation tasks. Reconfigurable Motion Generators are a new class of mechanical devices that are designed for a specific part family and their associated motion generation tasks. The research endeavors to realize a novel concept for Reconfigurable Motion Generators (RMGs) for multi-phase planar motion generation. Reconfigurable Motion Generators are capable of configuration changes according to variations in the motion generation requirements. Thus, Reconfigurable Motion Generators bridge the gap between the relative high flexibility and high cost of totally flexible devices (e.g., industrial robots) and the low flexibility and low cost of fully dedicated devices (e.g., cams and linkages). This paper introduces the concept of Reconfigurable Motion Generators that may be deployed in various automated manufacturing environments involving multi-phase motion generation tasks. The development, manufacturing, and testing of a prototype and the control system for a planar Reconfigurable Motion Generator based on a five-bar mechanism are discussed.     

关于空间解析几何的学术形态和教育形态

空间解析几何知识需要形式化的表述,而学生掌握空间解析几何知识需要经过思考,需要追根求源．作为教师,必须善于将空间解析几何的学术形态转化为教育形态,激发学生的学习兴趣和主动性．结合自己在空间解析几何教学实践中的体会,给出了一些实例．     

On Versal Unfoldings of Singularities for General Two-Dimensional Spatial Motions

Local models are given for singularities which can appear on the trajectories of general two-dimensional spatial motions. Versal unfoldings of these model singularities give rise to computer generated pictures describing the family of trajectories arising from small deformations of the tracing point.     

The Calculator as a Cognitive Tool: Upper-Primary Pupils Tackling a Realistic Number Problem

This paper examines the idea that the arithmetic calculator can act as a cognitive tool, supporting the amplification or reorganisation of systems of thought. It analyses how a structured sample of pupils in the last year of English primary education, with differing degrees of experience of a ’calculator-aware‘ number curriculum, tackled a realistic number problem, focusing on their use of calculator, written and mental modes of computation. Examples were found in which use of the calculator helped pupils to work with unusual problem representations, and to adopt solution strategies in which they focused on planning and monitoring computations executed by the machine. For most pupils, however, other issues were more salient. First, there was an important dissonance between pupils‘ conception of division and the calculator‘s operationalisation of it, although some cases showed how further experiment or computation with the machine could help to make appropriate connections. Second, while the calculator made it possible to redistribute computation from human to machine, important limitations arose from the transience of the calculator‘s record of operations and results. The observations suggest the importance of developing pupils‘ skill in making effective use of the calculator beyond single, simple computations; and the need to help pupils apprehend the relationship between mathematical concepts and their operationalisation in the machine. This revised version was published online in July 2006 with corrections to the Cover Date.     

浅谈现代教学和传统教学的结合

浅谈使用电子教案进行教学的体会 .揭示了如何充分利用现代教学技术的优势 .重点论述了如何在日常教学活动中把现代教学和传统教学有机地结合起来 ,以充分体现现代教育思想 ,培养创新型人才     

Robot Manipulations: A Synergy of Visualization, Computation and Action for Spatial Instruction

This article considers the use of a learning environment, RoboCell, where manipulations of objects are performed by robot operations specified through the learner's application of mathematical and spatial reasoning. A curriculum is proposed relating to robot kinematics and point-to-point motion, rotation of objects, and robotic assembly of spatial puzzles. Various instructional methods are supported by the RoboCell robot system, such as interactive demonstrations, modeling, computer simulations and robot operations, providing diverse activities in spatial perception, mental rotation and visualization. Pre-course and post-course tests in two middle schools and a high school indicated significant student progress in the tasks related to the categories of spatial ability which were practiced in the course. This revised version was published online in July 2006 with corrections to the Cover Date.     

Divergent-beam Lidar imaging in turbid water

Although there are rapid developments of underwater robotics vehicles in recent years, the underwater visual sensing or/and underwater imaging is still regarded as a major undertaking challenge, particularly in turbid water condition. Currently, a divergent-beam underwater Lidar imaging (UWLI) system has been finished and it precisely captured nano-seconds fast-gated images in highly turbid water. This permits the receiver to collect only the image-containing light pulse returned by the target and thus reduce the water-scattering related noise of underwater image dramatically. The end result is greatly improved intensity and contrast of the detected images. Based on our newly designed series targets, we are the first to successfully demonstrate UWLI in such a short 3 m water tank, and show the fast range-gated phenomenon in water much more clearly. The attenuation coefficients in turbid waters are 1.0 m and 2.3 m⁻¹, respectively.     

Technological Tools in the Introductory Statistics Classroom: Effects on Student Understanding of Inferential Statistics

While technology has become an integral part of introductory statistics courses, the programs typically employed are professional packages designed primarily for data analysis rather than for learning. Findings from several studies suggest that use of such software in the introductory statistics classroom may not be very effective in helping students to build intuitions about the fundamental statistical ideas of sampling distribution and inferential statistics. The paper describes an instructional experiment which explored the capabilities of Fathom, one of several recently-developed packages explicitly designed to enhance learning. Findings from the study indicate that use of Fathom led students to the construction of a fairly coherent mental model of sampling distributions and other key concepts related to statistical inference. The insights gained point to a number of critical ingredients that statistics educators should consider when choosing statistical software. They also provide suggestions about how to approach the particularly challenging topic of statistical inference. This revised version was published online in July 2006 with corrections to the Cover Date.