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煤矿巷道中粉尘对电磁波传播特性的影响 总被引:1,自引:1,他引:0
针对煤矿巷道中粉尘对电磁波传播的影响进行了理论上的研究,推导出电磁波传输衰减的损耗公式.研究表明,由于粉尘的存在,随着传播电磁波频率的增加,衰减在增大,当粉尘浓度为4.35 ×109个/m3时,在1 GHz时的衰减为5 dB/hm,在10 GHz时的衰减约为47 dB/hm.随着粉尘浓度的增大,衰减在增大,当发射频率为1 GHz时,在5×1010个/m3的浓度时,衰减为54 dB/hm.巷道中粉尘的浓度决定了传播电磁波衰减的大小,在国家规定的粉尘浓度以下,对电磁波的衰减值小于5 dB/hm. 相似文献
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空气隧道中的水汽分子能够吸收电磁波从而造成传输损耗。在开采工作面处,相对湿度很大甚至过饱和,又由于粉尘的存在,水汽分子不可避免会凝结成雾滴,电磁波入射到雾滴上形成瑞利散射引起衰减,电磁波通过雾滴时引起交叉极化和噪声,水汽浸润隧道壁后,壁的电导率几乎增加了10倍,由此电导率引起的衰减增大。 相似文献
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研究了电导率σ在煤矿圆形巷道中对电磁波传播的影响,并得出:在圆形巷道中,由于电导率σ的存在,使得圆形巷道波模的衰减随着频率的增加而单调增大,但是TE01波模的衰减却是随频率增加而单调下降,因此,TE01波模更适合在圆形巷道中传播。 相似文献
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研究了在300MHz以下频段,矩形巷道中存在电导率σ时电磁波传播的特性.研究表明,电磁波的传播具有很强的波导效应.巷道的截面越大,越有利于电波的传播.如果传播电波的频率低于截止频率,则衰减只和传播的频率有关.在截止频率以上,电导率越小,电磁波传播损耗越大;在相同的电导率下,随着频率的增加,衰减也将增加.TE波更适合于在巷道中传播. 相似文献
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拱形巷道是煤矿井下最常见的一种巷道。分析了电磁波在空拱形巷道中的传输特性。运用波导理论并结合数值计算法推导出巷道内电磁波的衰减率计算公式。对传输频率、巷道横截面以及围岩介质电参数对电磁波传输衰减率的影响进行了仿真。结果表明,在300~3000MHz特高频段,工作频率越高衰减越小;巷道横截面积越大衰减率越小;围岩介质的相对介电常数越大,衰减越大,且介电常数的变化对垂直极化波的影响大于水平极化波;围岩介质的电导率对衰减的影响不大,可忽略不计。 相似文献
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分析了电磁波在空拱形巷道中的传输特性。运用波导理论并结合数值计算法推导出巷道内的衰减率计算公式。对传输频率、巷道横截面以及围岩介质电参数对电磁波传输衰减率的影响做了软件仿真。结果表明:在300~3000MHz特高频段,工作频率越高衰减越小,巷道横截面积越大衰减率越小,围岩介质的相对介电常数越大,衰减越大,且介电常数的变化对垂直极化波的影响大于水平极化波,围岩介质的电导率对衰减的影响不大,可忽略不计。 相似文献
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分析了电磁波在空拱形巷道中的传输特性。运用波导理论并结合数值计算法推导出巷道内的衰减率计算公式。对传输频率、巷道横截面以及围岩介质电参数对电磁波传输衰减率的影响做了软件仿真。结果表明:在300~3000MHz特高频段,工作频率越高衰减越小,巷道横截面积越大衰减率越小,围岩介质的相对介电常数越大,衰减越大,且介电常数的变化对垂直极化波的影响大于水平极化波,围岩介质的电导率对衰减的影响不大,可忽略不计。 相似文献
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粘结抑尘方法的研究与试验 总被引:7,自引:0,他引:7
对NCZ-1粉的粘尘作用原理,及其在不同空气湿度下的粘尘能力与保湿时间进行了测定和研究,通过在煤矿井下的应用试验,分析不同粘度的NCZ-1粉实际粘尘效果,保湿时间及其影响因素、落尘的含水量变化规律等问题,结果表明,在一般的矿井条件下,NCZ-1粉不仅能够持续粘尘达25d以上,而且还可减少落尘的二次飞扬。 相似文献
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The present communication gives a general view of the methods of dust control in the Belgian coal mines at the beginning of 1977. The statistical data received from the mines are presented in tabular form. The length and the output of coal faces treated by the classical methods of pre-spraying of the wall, wet cutting, water infusion and wet pneumatic picks, are given separately; in some cases two or more of these technics are used together on the same coal face. The number of hard headings in which different methods of dust suppression are used, is also given. 相似文献
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The present communication gives a general view of the methods of dust control in the Belgian coal mines at the beginning of 1976. The statistical data received from the mines are presented in tabular form. The length and the output of coal faces treated by the classical methods of pre-spraying of the wall, wet cutting, water infusion and wet pneumatic picks, are given separately; in some cases two or more of these technics are used together on the same coal face. The number of stone drivages in which different methods of dust control are used, is also given. 相似文献
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采用终端开路同轴探头反射法测量了含水率0%~5%的氯化钠反射系数,研究了微波频率、含水率和温度对氯化钠含水物料吸波性能的影响,并对氯化钠的微波干燥工艺进行分析。结果表明:微波频率在2.3~2.6 GHz对物料的吸波性能影响不大,含水率的增加能显著提高物料的吸波能力和微波能的耗散,氯化钠的吸波性能与含水率之间存在线性关系,温度升高也会引起物料吸波性能显著提升;通过对物料微波干燥工艺研究得到较好的微波干燥工艺条件:干燥温度60~70℃、干燥时间70~90 s、物料厚度35~45 mm。 相似文献
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The present communication gives a general view of the methods of dust control in the Belgian coal mines at the beginning of 1974. The statistical data received from the mines are presented in tabular form. The length and the output of coal faces treated by the classical methods of pre-spraying of the wall, wet cutting, water infusion and wet pneumatic picks, are given separately; in some cases two or more of these techniques are used together on the same coal face. The number of stone drivages in which different methods of dust control are used, are also given. 相似文献
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The present communication gives a general view of the methods of dust control in the Belgian coal mines at the beginning of 1979. The statistical data received from the mines are presented in tabular form. The length and the output of coal faces treated by the classical methods of pre-spraying of the wall, wet cutting and water infusion are given separately; in some cases two or more of these technics are used together on the same coal face. The number of stone drivages in which different methods of dust control are used, is also given. 相似文献