基于Lucene的全文检索技术在电力项目计划审核中的应用

随着信息技术的发展,国家电网公司亟待改变人工项目审核的现状,实现项目重复审核自动化。因此,提出了基于Lucene的全文检索技术在电力项目计划审核方面的应用方案。首先深入分析了国家电网公司的项目审核现状和全文检索技术的研究现状,其次简单介绍了全文检索技术和Lucene全文检索引擎的概念,然后详细介绍了全文检索过程;最后将全文检索技术引入电力企业项目计划审核,给出了一个基于全文检索的电力企业项目计划审核系统的架构设计。使用Lucene全文检索引擎进行企业专项项目重复审核,可以方便、快速地获得检索排序结果和文档相似度,并且检索准确度高。     

Microscopic degradation mechanism of polyimide film caused by surface discharge under bipolar continuous square impulse voltage

Polyimide （PI） film is an important type of insulating material used in inverter-fed motors. Partial discharge （PD） under a sequence of high-frequency square impulses is one of the key factors that lead to premature failures in insulation systems of inverter-fed motors. In order to explore the damage mechanism of PI film caused by discharge, an aging system of surface discharge under bipolar continuous square impulse voltage （BCSIV） is designed based on the ASTM 2275 01 standard and the electrical aging tests of PI film samples are performed above the partial discharge inception voltage （PDIV）. The chemical bonds of PI polymer chains are analyzed through Fourier transform infrared spectroscopy （FTIR） and the dielectric properties of unaged and aged PI samples are investigated by LCR testers HIOKI 3532-50. Finally, the micro-morphology and micro-structure changes of PI film samples are observed through scanning electron microscopy （SEM）. The results show that the physical and chemical effects of discharge cut off the chemical bonds of PI polymer chains. The fractures of ether bond （C-O-C） and imide ring （C-N-C） on the backbone of a PI polymer chain leads to the decrease of molecular weight, which results in the degradation of PI polymers and the generation of new chemical groups and materials, like carboxylic acid, ketone, aldehydes, etc. The variation of microscopic structure of PI polymers can change the orientation ability of polarizable units when the samples are under an AC electric field, which would cause the dielectric constant e to increase and dielectric loss tan ~ to decrease. The SEM images show that the degradation path of PI film is initiated from the surface and then gradually extends to the interior with continuous aging. The injection charge could result in the PI macromolecular chain degradation and increase the trap density in the PI oolvmer bulk.