In this study, the changes of a vacuum arc＇s appearance were observed and the volt-ampere characteristics of the vacuum arc at intermediate frequency were analyzed under a transverse magnetic field （TMF）. The TMF a...In this study, the changes of a vacuum arc＇s appearance were observed and the volt-ampere characteristics of the vacuum arc at intermediate frequency were analyzed under a transverse magnetic field （TMF）. The TMF and phase shift time were calculated by using the TMF contact model and the large phase shift of the magnetic field at a higher frequency was conductive to the dispersion process of residual plasma. The arc velocity was higher at 800 Hz than at 400 Hz. It can be inferred that TMF will encourage arc movement at 800 Hz. Moreover, the arc movement has an impact on the arc voltage. Because of the increasing length of the arc column with a high arc velocity, the elongated arc causes the arc voltage to increase. Specifically, the volt-ampere characteristics of the vacuum arc are divided into three stages in this paper. The higher the frequency, the greater the initial rate of rise in the arc voltage and the larger the area surrounded by arc volt-ampere characteristics. The correlations between the arc voltage and the amplitude and frequency of the current are also presented.展开更多
A slotted orifice has many superiorities over a standard orifice.For single-phase flow measurement,its flow coefficient is insensitive to the upstream velocity profile.For two phase flow measurement,various character-...A slotted orifice has many superiorities over a standard orifice.For single-phase flow measurement,its flow coefficient is insensitive to the upstream velocity profile.For two phase flow measurement,various character-istics of its differential pressure(DP)are stable and closely correlated with the mass flow rate of gas and liquid.The complex relationships between the signal features and the two-phase flow rate are established through the use of a back propagation(BP)neural network.Experiments were carried out in the horizontal tubes with 50mm inner di-ameter,operated with water flow rate in the range of 0.2m3·h-1 to 4m3·h-1,gas flow rate in the range of 100m3·h-1 to 1000m3·h-1,and pressure at 400kPa and 850kPa respectively,where the temperature is ambient temperature.This article includes the principle of wet gas meter development,the experimental matrix,the signal processing techniques and the achieved results.On the basis of the results it is suggested that the slotted orifice couple with a trained neural network may provide a simple but efficient solution to the wet gas meter development.展开更多
In our design, an amalgamated-signal cymometer is developed with a TMS320F28335 DSP chip ---- we use its on-chip 12-bit 16-channel AD to conduct a novel dual-sequencer synchronize sampling and averaged to improve the ...In our design, an amalgamated-signal cymometer is developed with a TMS320F28335 DSP chip ---- we use its on-chip 12-bit 16-channel AD to conduct a novel dual-sequencer synchronize sampling and averaged to improve the accuracy. Considering the algorithm, we use TI's C28x_FPU_Lib to conduct a FFT with sampled results and correct spectrum with?Time-Shift Phase Difference Correcting Spectrum Method based on all-phase spectral analysis. Namely, we design a sampling-frequency self-adaption algorithm which makes operation keep on without outside-hardware command. Actually, the test result shows that our design's frequency resolution ratio is up to 0.4%, and the maximum frequency’s D-value between main and minor signal is up to 29.99 kHz.展开更多
基金supported by Special Scientific and Research Funds for Doctoral Specialty of Institution of Higher Learning (200800060004)National Natural Science Foundation of China (No. 51177004)by the Innovation foundation of BUAA for Ph.D Graduates
文摘In this study, the changes of a vacuum arc＇s appearance were observed and the volt-ampere characteristics of the vacuum arc at intermediate frequency were analyzed under a transverse magnetic field （TMF）. The TMF and phase shift time were calculated by using the TMF contact model and the large phase shift of the magnetic field at a higher frequency was conductive to the dispersion process of residual plasma. The arc velocity was higher at 800 Hz than at 400 Hz. It can be inferred that TMF will encourage arc movement at 800 Hz. Moreover, the arc movement has an impact on the arc voltage. Because of the increasing length of the arc column with a high arc velocity, the elongated arc causes the arc voltage to increase. Specifically, the volt-ampere characteristics of the vacuum arc are divided into three stages in this paper. The higher the frequency, the greater the initial rate of rise in the arc voltage and the larger the area surrounded by arc volt-ampere characteristics. The correlations between the arc voltage and the amplitude and frequency of the current are also presented.
基金Supported by the National Natural Science Foundation of China (No.60672003)Shandong Key Technology R&D Program (2004GG2205016).
文摘A slotted orifice has many superiorities over a standard orifice.For single-phase flow measurement,its flow coefficient is insensitive to the upstream velocity profile.For two phase flow measurement,various character-istics of its differential pressure(DP)are stable and closely correlated with the mass flow rate of gas and liquid.The complex relationships between the signal features and the two-phase flow rate are established through the use of a back propagation(BP)neural network.Experiments were carried out in the horizontal tubes with 50mm inner di-ameter,operated with water flow rate in the range of 0.2m3·h-1 to 4m3·h-1,gas flow rate in the range of 100m3·h-1 to 1000m3·h-1,and pressure at 400kPa and 850kPa respectively,where the temperature is ambient temperature.This article includes the principle of wet gas meter development,the experimental matrix,the signal processing techniques and the achieved results.On the basis of the results it is suggested that the slotted orifice couple with a trained neural network may provide a simple but efficient solution to the wet gas meter development.
文摘In our design, an amalgamated-signal cymometer is developed with a TMS320F28335 DSP chip ---- we use its on-chip 12-bit 16-channel AD to conduct a novel dual-sequencer synchronize sampling and averaged to improve the accuracy. Considering the algorithm, we use TI's C28x_FPU_Lib to conduct a FFT with sampled results and correct spectrum with?Time-Shift Phase Difference Correcting Spectrum Method based on all-phase spectral analysis. Namely, we design a sampling-frequency self-adaption algorithm which makes operation keep on without outside-hardware command. Actually, the test result shows that our design's frequency resolution ratio is up to 0.4%, and the maximum frequency’s D-value between main and minor signal is up to 29.99 kHz.
