A new approach to conductive electromagnetic interference （EMI） noise source modeling, i. e. the source internal impedance extraction, is presented. First, the impedance magnitude is achieved through an exciting pro...A new approach to conductive electromagnetic interference （EMI） noise source modeling, i. e. the source internal impedance extraction, is presented. First, the impedance magnitude is achieved through an exciting probe and a detecting probe, or through calculations based on insertion loss measurement results when inserting a series nigh-value known impedance or a shunt low-value known impedance in the circuit. Then the impedance phase is extracted by the Hilbert transform （HT） of the logarithm of the obtained impedance magnitude. Performance studies show that the estimated phase error can increase greatly at a zero frequency in the Hilbert transform because of the existence of a singular point, and this effect can be eliminated by introducing a zero-point when the noise source does not include a series-connected capacitive component. It is also found that when the frequency is nigher than 150 kHz, the estimated phase error is not sensitive to the inductive source but sensitive to the capacitive source. Finally, under the conditions of the same measurement accuracies for impedance magnitude, the accuracy of complex impedance based on the HT can be improved about 10 times when compared with the accuracy of estimated parameters based on the impedance magnitude fitting method （IMFM）.展开更多
在美国,1981年就有七千万起运动损伤,这些损伤或者是需要医务护理,或者是至少某一日的活动受到限制。最保守的估计,单单是在体育和娱乐中每年就要发生三百万到五百万起损伤事件(Krans C Couroy 1984)。这一严重的事实提醒了我们有必要...在美国,1981年就有七千万起运动损伤,这些损伤或者是需要医务护理,或者是至少某一日的活动受到限制。最保守的估计,单单是在体育和娱乐中每年就要发生三百万到五百万起损伤事件(Krans C Couroy 1984)。这一严重的事实提醒了我们有必要深入地研究一下运动损伤的本质和隐含规律。有些研究成果对鉴别可能造成损伤的高危险性因素很有帮助,并且对我们制定一些能够降低损伤危险性的预测措施有一定的参考价值。展开更多
基金The Natural Science Foundation of Jiangsu Province(No.BK2008429)Open Research Foundation of State Key Laboratory of Millimeter Waves of Southeast University(No.K200603)+1 种基金China Postdoctoral Science Foundation(No.20080431126)Jiangsu Postdoctoral Science Foundation(No.2007-337)
文摘A new approach to conductive electromagnetic interference （EMI） noise source modeling, i. e. the source internal impedance extraction, is presented. First, the impedance magnitude is achieved through an exciting probe and a detecting probe, or through calculations based on insertion loss measurement results when inserting a series nigh-value known impedance or a shunt low-value known impedance in the circuit. Then the impedance phase is extracted by the Hilbert transform （HT） of the logarithm of the obtained impedance magnitude. Performance studies show that the estimated phase error can increase greatly at a zero frequency in the Hilbert transform because of the existence of a singular point, and this effect can be eliminated by introducing a zero-point when the noise source does not include a series-connected capacitive component. It is also found that when the frequency is nigher than 150 kHz, the estimated phase error is not sensitive to the inductive source but sensitive to the capacitive source. Finally, under the conditions of the same measurement accuracies for impedance magnitude, the accuracy of complex impedance based on the HT can be improved about 10 times when compared with the accuracy of estimated parameters based on the impedance magnitude fitting method （IMFM）.
文摘在美国,1981年就有七千万起运动损伤,这些损伤或者是需要医务护理,或者是至少某一日的活动受到限制。最保守的估计,单单是在体育和娱乐中每年就要发生三百万到五百万起损伤事件(Krans C Couroy 1984)。这一严重的事实提醒了我们有必要深入地研究一下运动损伤的本质和隐含规律。有些研究成果对鉴别可能造成损伤的高危险性因素很有帮助,并且对我们制定一些能够降低损伤危险性的预测措施有一定的参考价值。
