Electrochemical quartz crystal impedance system (EQCIS) which allows in situ dynamic quartz crystal impedance measurement in an electrochemical experiment was developed by combining an HP 4395A Network/Spectrum/Impeda...Electrochemical quartz crystal impedance system (EQCIS) which allows in situ dynamic quartz crystal impedance measurement in an electrochemical experiment was developed by combining an HP 4395A Network/Spectrum/Impedance analyzer with an EG&G M283 potentiostat. Equivalent circuit parameters of crystal resonance change significantly during electrodeposition and dissolution of copper in 0.1 mol/L H2SO4 aqueous solution in a cyclic potential sweep experiment, which is explained with an overall picture of mass loading, solution density and viscosity, etc..展开更多
The electrochemical quartz crystal impedance system (EQCIS) has been used for the study of a partially immersed Au electrode in 0.2 mol/L NaClO4 aqueous solution. The influences of the immersed area and height of the ...The electrochemical quartz crystal impedance system (EQCIS) has been used for the study of a partially immersed Au electrode in 0.2 mol/L NaClO4 aqueous solution. The influences of the immersed area and height of the electrode on the EQCIS responses were evaluated, showing the highest response sensitivity to liquid loading at the center of the piezoelectric quartz crystal electrode. The increase in the immersed height of the Au electrode at oxygen reduction potentials during potential cycling was measured by this technique.展开更多
GaN HEMT器件在高频和大功率通信领域有着广泛的应用。在流片制造过程中,手动微波测试已不能满足器件性能监控的要求。本文在改进传统手动测试的基础上,介绍了一种基于Agilent VEE语言来实现器件微波小信号自动测试系统的方法。该系统...GaN HEMT器件在高频和大功率通信领域有着广泛的应用。在流片制造过程中,手动微波测试已不能满足器件性能监控的要求。本文在改进传统手动测试的基础上,介绍了一种基于Agilent VEE语言来实现器件微波小信号自动测试系统的方法。该系统解决了器件自动测试、等效电路参数计算和数据存储等问题,实现了整个测试过程自动化,大幅提升了测试效率。展开更多
为了研究交流电压作用下非线性半导体器件和非线性绝缘电介质的绝缘状态和介电性能,提出一种阻性和容性电流分解算法。以非线性电阻和非线性电容构成的并联等效电路为研究对象,推导响应电流关于激励电压的非线性方程。通过坐标变换,将...为了研究交流电压作用下非线性半导体器件和非线性绝缘电介质的绝缘状态和介电性能,提出一种阻性和容性电流分解算法。以非线性电阻和非线性电容构成的并联等效电路为研究对象,推导响应电流关于激励电压的非线性方程。通过坐标变换,将其转化成多元线性方程。利用多元线性回归方法,获得等效电路参数且实现了阻性和容性电流的分解。定性分析该算法的抗干扰能力和对非标准正弦波电压的适应能力。仿真结果表明:该算法可以准确地实现阻性和容性电流的分解;当响应电流含有55 d B的噪声时,电路参数的求解误差较小;激励电压谐波分量对电路参数的求解几乎没有影响。实验结果表明:该算法可以实现MOA阀片在交流电压作用下全泄露电流的分解。展开更多
We report a resonant method to measure the wall capacitance（C_w） and solution resistance（R_S） in a capacitively coupled contactless conductivity detector（C^4D）.Under the typical operating conditions in capillary...We report a resonant method to measure the wall capacitance（C_w） and solution resistance（R_S） in a capacitively coupled contactless conductivity detector（C^4D）.Under the typical operating conditions in capillary electrophoresis（I.D.50μm,O.D. 360μm,electrode length of 4 mm,electrode gap of 1 mm,frequency of 200 kHz）,the values of C_w measured in 1 and 20 mmol/L NaCl solutions are 2.8 and 32 fF,which are only 1.1%and 12%of prediction by the equation in references,respectively.The value of R_S is less than the prediction in solutions withκ〈0.02 S/m.The response current of C^4D is due to the change in C_w because the total impedance of a C^4D is composed mainly by the impedance from C_w.展开更多
文摘Electrochemical quartz crystal impedance system (EQCIS) which allows in situ dynamic quartz crystal impedance measurement in an electrochemical experiment was developed by combining an HP 4395A Network/Spectrum/Impedance analyzer with an EG&G M283 potentiostat. Equivalent circuit parameters of crystal resonance change significantly during electrodeposition and dissolution of copper in 0.1 mol/L H2SO4 aqueous solution in a cyclic potential sweep experiment, which is explained with an overall picture of mass loading, solution density and viscosity, etc..
基金This work was supported by the National Natural Science Foundation of China the Science and Technology Foundation of Hunan P
文摘The electrochemical quartz crystal impedance system (EQCIS) has been used for the study of a partially immersed Au electrode in 0.2 mol/L NaClO4 aqueous solution. The influences of the immersed area and height of the electrode on the EQCIS responses were evaluated, showing the highest response sensitivity to liquid loading at the center of the piezoelectric quartz crystal electrode. The increase in the immersed height of the Au electrode at oxygen reduction potentials during potential cycling was measured by this technique.
文摘为了研究交流电压作用下非线性半导体器件和非线性绝缘电介质的绝缘状态和介电性能,提出一种阻性和容性电流分解算法。以非线性电阻和非线性电容构成的并联等效电路为研究对象,推导响应电流关于激励电压的非线性方程。通过坐标变换,将其转化成多元线性方程。利用多元线性回归方法,获得等效电路参数且实现了阻性和容性电流的分解。定性分析该算法的抗干扰能力和对非标准正弦波电压的适应能力。仿真结果表明:该算法可以准确地实现阻性和容性电流的分解;当响应电流含有55 d B的噪声时,电路参数的求解误差较小;激励电压谐波分量对电路参数的求解几乎没有影响。实验结果表明:该算法可以实现MOA阀片在交流电压作用下全泄露电流的分解。
基金supported by the National Natural Science Foundation of China(nos.20975062 and 21175084)
文摘We report a resonant method to measure the wall capacitance（C_w） and solution resistance（R_S） in a capacitively coupled contactless conductivity detector（C^4D）.Under the typical operating conditions in capillary electrophoresis（I.D.50μm,O.D. 360μm,electrode length of 4 mm,electrode gap of 1 mm,frequency of 200 kHz）,the values of C_w measured in 1 and 20 mmol/L NaCl solutions are 2.8 and 32 fF,which are only 1.1%and 12%of prediction by the equation in references,respectively.The value of R_S is less than the prediction in solutions withκ〈0.02 S/m.The response current of C^4D is due to the change in C_w because the total impedance of a C^4D is composed mainly by the impedance from C_w.
