In this study,the characteristics of Electromagnetic(EM) radiation caused by Electrostatic Discharges(ESDs) from metal spheres charged to voltages less than 1 kV are examined experimentally.Our experimental system con...In this study,the characteristics of Electromagnetic(EM) radiation caused by Electrostatic Discharges(ESDs) from metal spheres charged to voltages less than 1 kV are examined experimentally.Our experimental system consists of a pair of spherical electrodes of different diameters,a 1-18 GHz-bandwidth horn antenna and a 20-GHz-bandwidth digitizing oscilloscope.Polarization,waveform duration and peaks of antenna-received voltages from the EM field radiation are measured in order to clarify the EM radiation mechanism.The ratio of the received voltages between the antenna arrangements of the field polarization parallel and perpendicular to the spark pass is 18 to 20 dB.The polarities of the antenna-received voltages are the same as those of the charge voltages across the gap.Moreover,the waveform duration and the first peaks increase with an increase in the diameters of the spherical electrodes.Consequently,we find that the polarization,waveform duration and first peaks of the EM field radiation can be explained by a dipole antenna structure,which makes the spark part of the spherical electrodes a feeding point on the straight line passing through the centres of the two spheres.展开更多
The variation in apparent charge of two typical variable charge soils resulting from Zn adsorption were studied by KC1 saturation and NH4NO3 replacement methods. Results showed that zinc were adsorbed specifically to ...The variation in apparent charge of two typical variable charge soils resulting from Zn adsorption were studied by KC1 saturation and NH4NO3 replacement methods. Results showed that zinc were adsorbed specifically to those sites with negative charge. As in different pH ranges, the percentages of specific and electrostatic adsorptions of zinc and the mechanisms of specific adsorption were different, the effects of Zn adsorption on apparent charge were varied and could be characterized as: when 1 mmol Zn2+ was adsorbed, a change about 1 mmol in the apparent charge was observed in the low pH range (Ⅰ), 1.4 to 1.5 mmol in the moderate pH range (Ⅱ) and 0.55 to 0.6 mmol in the high pH range (Ⅲ). These experimental data, in terms of soil charge, proved once more author's conclusion in the preceding paper (Sun, 1993) that in accordance with the behaviors of Zn adsorption by the variable charge soils in relation to pH, three pH ranges with different adsorption mechanisms were delineated; that is, in Range Ⅰ, specific adsorption was the predominant mechanism, in Ranges Ⅱ and Ⅲ, specific and electrostatic adsorptions co-existed, but their specific adsorption mechanisms were not identical.展开更多
文摘In this study,the characteristics of Electromagnetic(EM) radiation caused by Electrostatic Discharges(ESDs) from metal spheres charged to voltages less than 1 kV are examined experimentally.Our experimental system consists of a pair of spherical electrodes of different diameters,a 1-18 GHz-bandwidth horn antenna and a 20-GHz-bandwidth digitizing oscilloscope.Polarization,waveform duration and peaks of antenna-received voltages from the EM field radiation are measured in order to clarify the EM radiation mechanism.The ratio of the received voltages between the antenna arrangements of the field polarization parallel and perpendicular to the spark pass is 18 to 20 dB.The polarities of the antenna-received voltages are the same as those of the charge voltages across the gap.Moreover,the waveform duration and the first peaks increase with an increase in the diameters of the spherical electrodes.Consequently,we find that the polarization,waveform duration and first peaks of the EM field radiation can be explained by a dipole antenna structure,which makes the spark part of the spherical electrodes a feeding point on the straight line passing through the centres of the two spheres.
文摘The variation in apparent charge of two typical variable charge soils resulting from Zn adsorption were studied by KC1 saturation and NH4NO3 replacement methods. Results showed that zinc were adsorbed specifically to those sites with negative charge. As in different pH ranges, the percentages of specific and electrostatic adsorptions of zinc and the mechanisms of specific adsorption were different, the effects of Zn adsorption on apparent charge were varied and could be characterized as: when 1 mmol Zn2+ was adsorbed, a change about 1 mmol in the apparent charge was observed in the low pH range (Ⅰ), 1.4 to 1.5 mmol in the moderate pH range (Ⅱ) and 0.55 to 0.6 mmol in the high pH range (Ⅲ). These experimental data, in terms of soil charge, proved once more author's conclusion in the preceding paper (Sun, 1993) that in accordance with the behaviors of Zn adsorption by the variable charge soils in relation to pH, three pH ranges with different adsorption mechanisms were delineated; that is, in Range Ⅰ, specific adsorption was the predominant mechanism, in Ranges Ⅱ and Ⅲ, specific and electrostatic adsorptions co-existed, but their specific adsorption mechanisms were not identical.
