A new humidity calibration facility using a 2-T （two-temperature）, constant pressure principle for generating gas of known humidity has been developed at NIS for primary realization of relative humidity scale in the...A new humidity calibration facility using a 2-T （two-temperature）, constant pressure principle for generating gas of known humidity has been developed at NIS for primary realization of relative humidity scale in the range from 13% to 98% for calibrating and testing hygrometers to improve the uncertainty. This paper reports the construction of the 2-T humidity generator describing its saturator and the test chamber system. Results of the efficiency tests of its saturator showed satisfactory generation performance for a primary realization of relative humidity scale. The expanded uncertainty of the relative humidity with a coverage factor k = 2 was found to be from ± 0.25 % to ± 0.67%.展开更多
In order to achieve high precision measurement of inductance in a wide frequency range,a method of inductance measurement based on double-excitation auto-balancing bridge is proposed.In this method,the direct digital ...In order to achieve high precision measurement of inductance in a wide frequency range,a method of inductance measurement based on double-excitation auto-balancing bridge is proposed.In this method,the direct digital synthesizer(DDS)as signal generator is used as the bridge excitation source,and the bridge is automatically balanced by adjusting and measuring the voltage ratio.Using standard resistors,the system can achieve high precision measurement of four-terminal pair inductors in the frequency range of 100Hz-100kHz.Aiming at the low efficiency of bridge balancing,an iterative balancing algorithm based on the steepest descent method is proposed.In order to suppress the interference caused by the initial phase change and non-integer periodic sampling,the high-precision measurement of the complex impedance of inductance is realized based on the all-phase fast Fourier transform(apFFT).Finally,the corresponding measurement system is built and the inductance measurement experiment is carried out.The experimental results show that the relative error of the system for inductance measurement can be as low as 0.009%,and the optimal relative measurement uncertainty of the system can reach 9.89×10^(-4)compared with 5×10^(-5)of commercial impedance analyzer.展开更多
文摘A new humidity calibration facility using a 2-T （two-temperature）, constant pressure principle for generating gas of known humidity has been developed at NIS for primary realization of relative humidity scale in the range from 13% to 98% for calibrating and testing hygrometers to improve the uncertainty. This paper reports the construction of the 2-T humidity generator describing its saturator and the test chamber system. Results of the efficiency tests of its saturator showed satisfactory generation performance for a primary realization of relative humidity scale. The expanded uncertainty of the relative humidity with a coverage factor k = 2 was found to be from ± 0.25 % to ± 0.67%.
基金National Key Research and Development Plan Project(No.2020YFB2010800)National Natural Science Foundation of China(Nos.61905175,51775377,61971307)+4 种基金Fok Ying Tung Education Foundation(No.171055)China Postdoctoral Science Foundation(No.2020M680878)Guangdong Province Key Research and Development Plan Project(No.2020B0404030001)Tianjin Science and Technology Plan Project(No.20YDTPJC01660)Project of Foreign Affairs Committee of China Aviation Development Sichuan Gas Turbine Research Institute(Nos.GJCZ-2020-0040,GJCZ-2020-0041)。
文摘In order to achieve high precision measurement of inductance in a wide frequency range,a method of inductance measurement based on double-excitation auto-balancing bridge is proposed.In this method,the direct digital synthesizer(DDS)as signal generator is used as the bridge excitation source,and the bridge is automatically balanced by adjusting and measuring the voltage ratio.Using standard resistors,the system can achieve high precision measurement of four-terminal pair inductors in the frequency range of 100Hz-100kHz.Aiming at the low efficiency of bridge balancing,an iterative balancing algorithm based on the steepest descent method is proposed.In order to suppress the interference caused by the initial phase change and non-integer periodic sampling,the high-precision measurement of the complex impedance of inductance is realized based on the all-phase fast Fourier transform(apFFT).Finally,the corresponding measurement system is built and the inductance measurement experiment is carried out.The experimental results show that the relative error of the system for inductance measurement can be as low as 0.009%,and the optimal relative measurement uncertainty of the system can reach 9.89×10^(-4)compared with 5×10^(-5)of commercial impedance analyzer.
