共查询到19条相似文献,搜索用时 140 毫秒
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近期,由河北省计量院编制的《绝缘油介电强度测试仪》河北省地方检定规程和《有载分接开关则试仪》河北省地方校准规范组织专家进行了审毫。经过会议讨论,与会专家一致认为:该规程和规苞的制定填补了国内空白,为绝缘油介电强度测试义的检定、有载分接开关测试仪的校准工作提供了支术依据。 相似文献
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数字移动通信综合测试仪在手机或基站设备的研发、设计、生产中广泛使用,而调制质量又是无线通信测试仪最主要的参数,对无线通信测试的总体性能起着关键性的作用.以8960系列E5515C数字移动通信综合测试仪为例,介绍了1xEV-DO数字调制质量参数的校准,阐述了CDMA标准中波形质量和误差矢量幅度之间的关系,并通过矢量信号分析仪进行了测试与验证.最后,对测量结果进行了数字调制测量不确定度分析. 相似文献
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关于测量CDMA2000中Rho值和EVM值的问题 总被引:1,自引:0,他引:1
近几年.国家非常重视数字通信测量测试仪器的量传以及校准方法的规范.组织编制了3个相关的规范。分别是JJF1131-2005《TDMA—GSM数字移动通信综合测试仪校准规范》、JJF1128—2004《矢量信号分析仪校准规范》和JJF1174—2007(数字信号发生器校准规范》。但这些规范对CDMA技术中的特殊参量没有研究.例如表征信号质量的波形质量因数Rho和码域功率等. 相似文献
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采用反向沉淀法制备了Mg(OH)2-ZnO纳米粒子,通过原位聚合和热亚胺化的方法成功制备了不同纳米Mg(OH)2-ZnO粒子质量分数的纳米Mg(OH)2-ZnO/聚酰亚胺(PI)复合薄膜,通过SEM、热重分析、介电谱测试仪和击穿场强测试仪对薄膜的表面形貌、热稳定性、介电性能和击穿强度进行表征和测试。结果表明:Mg(OH)2-ZnO纳米粒子均匀地分散在PI基体中,Mg(OH)2-ZnO/PI热稳定性下降,介电常数、介电损耗和电导率增加,击穿场强随纳米粒子增加先增加后减小,在纳米粒子含量为2%时,达到最大值296 kV/mm。 相似文献
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Kida T Nakano T Fujino Y Matsumura C Miyawaki K Kato E Akashi M 《Analytical chemistry》2008,80(1):317-320
This paper describes the complete removal of chlorinated aromatic compounds from insulating oil by a channel-type gamma-cyclodextrin (gamma-CD) assembly as a new adsorbent. Using this type of adsorbent (50-60 wt % of oil), 1,2,4- and 1,3,5-trichlorobenzenes, 2- and 4-chlorobiphenyls (2- and 4-MCBs), 4,4'-dichlorobiphenyl (4,4'-DiCB), and 3,4,4'-trichlorobiphenyl (3,4,4'-TrCB), whose initial concentrations were 100 ppm, were completely removed from the insulating oil. Competitive adsorption experiments using a mixture of 2-MCB and 4-MCB or a mixture of 4-MCB, 4,4'-DiCB, and 3,4,4'-TrCB revealed that selective adsorption based on the shape and size of the chlorinated aromatics was achieved by the channel-type gamma-CD assembly, implying that inclusion into the cavity of the channel-type gamma-CD was responsible for the removal of chlorinated aromatics from insulating oil. It was also found that more than 70% of adsorbed chlorinated aromatics was easily recovered from the channel-type gamma-CD by simply washing with n-hexane, and chlorinated aromatics were completely removed from the insulating oil even by the regenerated adsorbent, indicating that the gamma-CD assembly can be easily regenerated and recycled. 相似文献
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Bizhan Mehrvarz Fatemeh Bahadori Saeed Zolfaghari Moghaddam 《Advanced Powder Technology》2019,30(2):221-226
A transformer is an electrical device that transfers electrical energy between windings by electromagnetic induction while producing a considerable amount of heat in circuits. The heat produced in windings is removed by an appropriate heat transfer fluid such as liquid dielectrics. The cooling and insulating of a liquid dielectric depend on the properties of the oil filling the transformer. One of the approaches to enhance the thermal and dielectric properties of transformer oil is employing an appropriate nanoparticle in a transformer.In this paper, a three-phase distribution transformer is simulated three-dimensionally in order to study the heat transfer efficiency for pure oil (single phase) and nanofluid (TiO2 nanoparticles- transformer oil). For both models, the electromagnetic field in solid sections and heat transfer in fluid and solid sections of the transformer are simultaneously investigated. The simulation results show that the presence of TiO2 nanoparticles in the transformer oil increases the heat transfer coefficient, i.e. adding 1% (vol/vol) of TiO2 nanoparticles to the transformer oil increases the Nusselt number from 2.17 to 2.49, while the maximum temperature of transformer components decreases from 47.20?°C to 43.05?°C. 相似文献
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本文基于高频电介质强度测试急需制定用于检测机构依据的校准方法,对该仪器的主要计量特性进行了研究和试验,确定了计量参数、允许误差和标准器具的选择及操作方法。 相似文献