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
The impedance of a solid state active phased array antenna varing with frequency and beam scanning scanning angle be matched with the solid state active matching network (SSAMN). In order to adjust and measure the rad...The impedance of a solid state active phased array antenna varing with frequency and beam scanning scanning angle be matched with the solid state active matching network (SSAMN). In order to adjust and measure the radar conveniently and Securely, it is necessary for the impedance of the simulator of the phased array antennas to be optimized.Having selected the PIN dilde controlling circuits and the circuit parameters optimized,the simulator circuit is determined through numerical computation The experiment is given in support of the simulation.展开更多
In order to provide some reference for the design of the power/ground system, a complicated power/ground system in time and frequency domains was analyzed, which is based on PEEC (Partial Element Equivalent Circuit). ...In order to provide some reference for the design of the power/ground system, a complicated power/ground system in time and frequency domains was analyzed, which is based on PEEC (Partial Element Equivalent Circuit). According to the actual requirements, characteristics of some common power/ground structures in time and frequency domains, such as SSN (Simultaneous Switching Noise), are obtained for the future research. The results show the first resonance point is changed with the structure of the power/ground networks.展开更多
Because of ground clutter wave interf e rence,it is difficult to measure smoke screen disturbance in the field.In this pape r,a kind of indoor measurement method of smoke screen disturbance efficiency ba sed on Gaussi...Because of ground clutter wave interf e rence,it is difficult to measure smoke screen disturbance in the field.In this pape r,a kind of indoor measurement method of smoke screen disturbance efficiency ba sed on Gaussian diffusion model is put forward.As a characteristic,the measur ement result of smoke screen area density proves that the indoor measurement met hod of smoke screen disturbance efficiency based on Gaussian diffusion model is fea sible.展开更多
Considering the continuous exploitation of marine resources, it is very important to study the anticorrosion performance and durability of zinc coated streel （ZCS） because its increasing use as reinforcements in sea...Considering the continuous exploitation of marine resources, it is very important to study the anticorrosion performance and durability of zinc coated streel （ZCS） because its increasing use as reinforcements in seawater. Tafel polarization curves and linear polarization curves combined with electrochemical impedance spectroscopy （EIS） were employed to evaluate the corrosion performance of ZCS at Qingdao test station during long-term immersion in seawater. The results indicated that the corrosion rate of the ZCS increased obviously with immersion time in seawater. The corrosion products that formed on the zinc coated steel were loose and porous, and were mainly composed of Zn5（OH）8C12, Zn5（OH）6（CO3）2, and ZnO. Pitting corrosion occurred on the steel surface in neutral seawater, and the rate of ZCS corrosion decreased with increasing pH.展开更多
The inter-line dynamic voltage restorer （IDVR） consists of several voltage source inverters connected to different independent distribution feeders with common dc bus. When one of the inverters compensates for volta...The inter-line dynamic voltage restorer （IDVR） consists of several voltage source inverters connected to different independent distribution feeders with common dc bus. When one of the inverters compensates for voltage sag that appears in its feeder （voltage control mode）, the other inverters pump the required power into the dc bus （power control mode）. Each inverter will have both voltage and power controllers; only one controller is in use during the abnormal conditions according to its feeder state. The voltage controller uses one of the dynamic voltage restoration techniques. In this paper, the in-phase technique is applied and two types of loads are considered （constant impedance and three phase induction motor）. Since the voltage restoration process may need real power injection into the distribution system, the power controller injects this power via voltage injection. This voltage injection is simulated by voltage drop across series virtual impedance. A new scheme is proposed to select the impedance value. The impedance value is selected such that the power consumed by this impedance represents the required power to be transferred without perturbing the load voltage. The performance of this system is also studied during voltage swell. A scheme for operation of multi-feeder IDVR system is proposed in this paper. Simulation results substantiate the proposed concept.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The impedance of a solid state active phased array antenna varing with frequency and beam scanning scanning angle be matched with the solid state active matching network (SSAMN). In order to adjust and measure the radar conveniently and Securely, it is necessary for the impedance of the simulator of the phased array antennas to be optimized.Having selected the PIN dilde controlling circuits and the circuit parameters optimized,the simulator circuit is determined through numerical computation The experiment is given in support of the simulation.
基金National Natural Science Foundation ofChina(No.60 2 710 3 0 )
文摘In order to provide some reference for the design of the power/ground system, a complicated power/ground system in time and frequency domains was analyzed, which is based on PEEC (Partial Element Equivalent Circuit). According to the actual requirements, characteristics of some common power/ground structures in time and frequency domains, such as SSN (Simultaneous Switching Noise), are obtained for the future research. The results show the first resonance point is changed with the structure of the power/ground networks.
文摘Because of ground clutter wave interf e rence,it is difficult to measure smoke screen disturbance in the field.In this pape r,a kind of indoor measurement method of smoke screen disturbance efficiency ba sed on Gaussian diffusion model is put forward.As a characteristic,the measur ement result of smoke screen area density proves that the indoor measurement met hod of smoke screen disturbance efficiency based on Gaussian diffusion model is fea sible.
基金Supported by the National Natural Science Foundation of China(No.41506098)the Post-Doctoral Fund of Zhejiang Province(No.BSH 1502160)+1 种基金the Open Fund Project of Key Laboratory of Marine Materials and Related Technologies of China Academy of Sciences(No.LMMT-KFKT-2014-008)the Ningbo Natural Science Foundation(No.2015A610016)
文摘Considering the continuous exploitation of marine resources, it is very important to study the anticorrosion performance and durability of zinc coated streel （ZCS） because its increasing use as reinforcements in seawater. Tafel polarization curves and linear polarization curves combined with electrochemical impedance spectroscopy （EIS） were employed to evaluate the corrosion performance of ZCS at Qingdao test station during long-term immersion in seawater. The results indicated that the corrosion rate of the ZCS increased obviously with immersion time in seawater. The corrosion products that formed on the zinc coated steel were loose and porous, and were mainly composed of Zn5（OH）8C12, Zn5（OH）6（CO3）2, and ZnO. Pitting corrosion occurred on the steel surface in neutral seawater, and the rate of ZCS corrosion decreased with increasing pH.
文摘The inter-line dynamic voltage restorer （IDVR） consists of several voltage source inverters connected to different independent distribution feeders with common dc bus. When one of the inverters compensates for voltage sag that appears in its feeder （voltage control mode）, the other inverters pump the required power into the dc bus （power control mode）. Each inverter will have both voltage and power controllers; only one controller is in use during the abnormal conditions according to its feeder state. The voltage controller uses one of the dynamic voltage restoration techniques. In this paper, the in-phase technique is applied and two types of loads are considered （constant impedance and three phase induction motor）. Since the voltage restoration process may need real power injection into the distribution system, the power controller injects this power via voltage injection. This voltage injection is simulated by voltage drop across series virtual impedance. A new scheme is proposed to select the impedance value. The impedance value is selected such that the power consumed by this impedance represents the required power to be transferred without perturbing the load voltage. The performance of this system is also studied during voltage swell. A scheme for operation of multi-feeder IDVR system is proposed in this paper. Simulation results substantiate the proposed concept.
