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介绍了澳大利亚悉尼大学物理学院在普通物理教学中采用的一种新的教学形式——Workshop tutorials.它是一种交互式的、相互合作、以学生为中心的教学方式,适应学生不同的学习风格,特别适合在普通物理教学中培养学生的自主学习、合作学习、科学研究、批判性思维、团队工作等科研能力. 相似文献
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采用磷酸-高碘酸钾比色法,通过大气采样器,定量抽取工作车间的空气空气中的各种飘浮物与被微孔滤膜阻留。用磷酸溶样,在酸性溶液中,锰及其化合物被高碘酸钾氧化而生成紫红色高碘酸盐,再用分光光度计比色测定。 相似文献
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Electrodynamic levitation devices, which utilizing eddy currents induced in the levitated item to produce the repulsive force, are being involved in many engineering applications due to its fast response. This kind of repulsion is particularly used in electromagnetic launcher, electromagnetic brake and other applications. To analyze and improve the dynamic behavior and performances of such devices, the conventional way is using the finite element method (FEM), due to its ability of using adaptive mesh to handle complex geometries. Nevertheless, it has a serious limitation in efficiency for large number of variables which is reflected by the high cost in terms of computational properties. During the past few years, the finite volume method FVM formulations have gained attention inside the electromagnetic community. The method has been proved its effectiveness in the solution of different kinds of problems, such as in magnetostatic field computation and eddy current nondestructive testing. The FVM method is particularly attractive thanks to its small required storage memory and reduced CPU time. In this paper an FVM model is developed to analyze the dynamic characteristic of the motion of the electrodynamic levitation device TEAM Workshop Problem 28. The dynamic characteristic of the motion is obtained by solving the electromagnetic equation coupled to the mechanical one. The repulsive force applied to the levitated plate of TEAM Workshop Problem 28, is computed by the interaction between eddy current induced in the plate and the magnetic flux density. A comparison between experimental and numerical results is carried out to show the efficiency of the developed model. What’s more, based on the developed FVM model, a fuzzy logic controller FLC is designed and implemented to control the position of the levitated item. 相似文献
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