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Multi-point grounding of the core is one of the common transformer faults. In this study, a homogenisation model based on the finite element method is developed for calculating multi-point grounding current of the transformer core. The equivalent conductivity in the direction normal to the laminations is determined by the analysis of fault current distribution and calculation of anisotropic resistances of the iron core, especially, considering the influence of insulation coating on the silicon steel sheet. The validity of the proposed model is verified by comparing the three-dimensional finite element simulation results with the experimental results. Finally, two typical faults are simulated to further study the characteristics of multi-point grounding current based on a distribution transformer, which may be useful for the optimisation of transformer core design.

As the development of information technology, multimedia technology and network technology, ubiquitous learning environment has gradually become one of the focuses of social research. This article is divided into three parts, the first part is to discuss the impact on library services in the ubiquitous learning environment; the second part is to discuss the characteristics of the user information needs in the ubiquitous environment; the third part is to discuss library services innovation in the ubiquitous environment.

There are some problems in university library appraisal, for example, appraised index system is imperfect, the benefit appraisal is imperfect, appraises personnel is sole. In order to promote the library enterprise development well, in university library appraisal process we should consummate the appraisal target system, pay attention to “nature” and “quantity” dual appraisals, appraises personnel comprehensively participate.