Results 51 to 60 of about 6,277 (141)
Research on borehole transient electromagnetic positioning method of azimuthal coil scanning detection [PDF]
The borehole transient electromagnetic method is used to detect the long-range water-bearing bodies around the borehole wall by using the advanced water exploration borehole in the heading roadway, which avoids the “one’s opinion in one hole” because the
Chenglin JIANG +3 more
core +1 more source
基于传递函数法的变压器感应式振荡操作冲击电压试验故障诊断技术研究
Gaoya dianqi, 2020 采用感应式振荡型操作冲击电压对变压器进行现场冲击耐压试验具有效率高、易于调波、试验设备体积小等优点。为了研究变压器匝间短路故障在感应式振荡操作冲击电压下的电压传递函数特性,构建了感应式振荡操作冲击电压下变压器的电压传递函数,建立了模拟变压器匝间短路的试验模型,并以该模型为试验对象搭建试验系统进行试验。通过分析试验数据后发现,存在匝间短路故障的变压器在感应式振荡操作冲击电压作用下,其电压传递函数与无故障时相比,极值点所在的频率升高,极值点的幅值降低。短路故障越严重,极值点的变化趋势越明显 ...
孙文星 +5 more
doaj
Design of Power Quality Surveillance [PDF]
, 2008 随着电网规模的扩大和现代科学技术的发展，电能质量显得越来越重要。这包含两方面的内容：一方面，造成电能质量问题的因素不断增长，如以电力装置为代表的非线性负荷的使用﹑各种大型用电设备的启停等造成大量电能问题。另一方面，各种复杂的﹑精密的﹑对电能质量敏感的用电设备不断普及，如高性能家用电器﹑办公设备﹑精密试验仪器﹑精密生产过程的自动控制设备等，对电能质量的要求越来越高，从目前的现状看，可以说电能质量问题已成为严重威胁电力网及国民经济的安全﹑经济﹑高效运行的问题，并影响产品质量和人民日常生活的生活质量 ...
李永萍
core
Physical simulation on directional shielding of receiving coil in borehole transient electromagnetic method [PDF]
Borehole transient electromagnetic(BTEM)scanning detection method uses the advanced exploration boreholes in the roadway to scan and detect the hidden geological anomalies outside the borehole wall by rotating the transceiver coil inside the borehole ...
Chengtao XIN +3 more
core +1 more source
A Study on Screen Printing of 13.56MHz RFID Tag Antennae [PDF]
, 2009 高频13.56MHzRFID标签产品具有广阔的市场前景，其中标签天线的性能直接决定着整个系统的性能。针对国内在13.56MHz射频网印天线方面研究的相对落后，为了解决在标签网印天线设计和制备工艺方面存在的空白状况，本文对具有低成本、环保节能的丝网印刷天线制造方式进行研究，围绕网印天线的设计和工艺，对其天线设计及网印技术进行开发，对标签不同形状、不同面积、不同应用要求的天线设计进行理论上的探讨，结合阻抗分析仪对天线电学性能测试和电镜的天线微观观测，总结天线设计的基本方法和规律 ...
黄辉明
core
Gaoya dianqi, 2018 同塔多回超/特高压输电线路因其相间距和回间距小而存在较大的感应电压、电流,直接影响线路的检修、运行和接地开关设备的选型。为此,文中以兰州东至乾县的750 kV同塔双回输电线路为例,利用ATP/EMPT电磁暂态仿真软件搭建同塔双回输电线路模型,分析了两回线路之间的水平间距、运行线路长度、地线高度、土壤电阻率以及运行电流对检修线路上产生的感应电压和感应电流的影响,给出了各种典型工况下流过检修人员的人体电流大小。结果表明:检修线路上产生的感应电压、电流与水平间距基本成反比例关系 ...
史志强 +6 more
doaj
Three-dimensional polarization amplitude modulator and demodulator [PDF]
, 2012 Based on the mathematical description of a space electromagnetic field,a novel approach to the three-dimen-sional joint modulation of the signal amplitude,polarization angle and polarization phase angle of an electromagnetic signal in wireless ...
Han-bin SONG +3 more
core
Establishment of intelligent shearer bus electromagnetic interference model and wiring process optimization [PDF]
Intelligent shearer is a key equipment for a fully mechanized coal mine working face. For intelligent shearers, due to the internal space limitation of flameproof electric control box, there are usually mixed wiring situations with the cables of internal
Dong WEI +6 more
core +1 more source
Dianci bileiqi, 2019 配电线路的绝缘水平较低,线路易受雷击影响产生雷电过电压进而导致闪络等故障,由雷电感应过电压导致的故障占线路故障总数的90%以上。本文研究了一种仿真计算配电线路雷电感应过电压的方法并分析了6种不同因素对配电线路雷电感应过电压的影响。为计算雷电感应过电压,本文选择TL模型作为雷电通道模型,选择Agrawal模型作为场线耦合模型,根据所选数学模型在ATP-EMTP中搭建出仿真模型对雷电感应过电压进行仿真计算,结果表明:雷击点距线路中点最近时线路中点雷电感应过电压是线路最大雷电感应过电压 ...
李悠然 +5 more
doaj
Ignition mechanism of methane by 5G electromagnetic waves and power safety thresholds in underground coal mines [PDF]
5G technology, with its advantages of high bandwidth, low latency, and extensive connectivity, has shown great potential in driving the intelligent transformation of the coal mining industry.
Haijian CHEN +6 more
core +1 more source