The structure,equivalent circuit,noise sources of silicon photodiode are analyzed.In order to improve the measuring linearity,we must choose the silicon photodiode with a large R d,small R s and I 0 and...The structure,equivalent circuit,noise sources of silicon photodiode are analyzed.In order to improve the measuring linearity,we must choose the silicon photodiode with a large R d,small R s and I 0 and under an operation state of output short-circuit.We must let the operation amplifier work in the current-voltage transfer form.Also we analyzed the effects of the input noise voltage,the input noise current,the input offset voltage,the input offset current of the operation amplifier and the noises of the silicon photodiode on the combined circuit of the operation amplifier with the silicon photodiode.Considering these factors,we can design the detective circuit with high response,sensitivity,stability,linearity and SNR .展开更多
Transmission of oesophageal images may vary between different small-bowel capsule endoscopy models. A retrospective review of 100 examinations performed with 2 different Small-bowel capsule endoscopy （SBCE） sys- te...Transmission of oesophageal images may vary between different small-bowel capsule endoscopy models. A retrospective review of 100 examinations performed with 2 different Small-bowel capsule endoscopy （SBCE） sys- tems （PillCam and MiroCam） was performed. The oral cavity/aero-digestive tract （i.e., tongue, uvula and/or epiglottis） was captured/identified in almost all （99%） of PillCam videos but in none of MiroCam cases, P 〈 0.0001. Furthermore, oesophageal images （i.e., from the upper oesophageal sphincter to the Z-line were cap- tured in 99% of PillCam videos （mean =1= SD, 60.5 ± 334.1 frames, range： 0-3329 frames） and in 66% of Mi- roCam cases （mean ± SD, 11.1 ± 46.5 frames, range： 0-382 frames）, P 〈 0.0001. The Z-line was identified in 42% of PilICam videos and 17% of MiroCam, P = 0.0002. This information might be useful when perform- ing SBCE in patients with high risks for aspiration.展开更多
The vibration signals of multi-fault rolling bearings under nonstationary conditions are characterized by intricate modulation features,making it difficult to identify the fault characteristic frequency.To remove the ...The vibration signals of multi-fault rolling bearings under nonstationary conditions are characterized by intricate modulation features,making it difficult to identify the fault characteristic frequency.To remove the time-varying behavior caused by speed fluctuation,the phase function of target component is necessary.However,the frequency components induced by different faults interfere with each other.More importantly,the complex sideband clusters around the characteristic frequency further hinder the spectrum interpretation.As such,we propose a demodulation spectrum analysis method for multi-fault bearing detection via chirplet path pursuit.First,the envelope signal is obtained by applying Hilbert transform to the raw signal.Second,the characteristic frequency is extracted via chirplet path pursuit,and the other underlying components are calculated by the characteristic coefficient.Then,the energy factors of all components are determined according to the time-varying behavior of instantaneous frequency.Next,the final demodulated signal is obtained by iteratively applying generalized demodulation with tunable E-factor and then the band pass filter is designed to separate the demodulated component.Finally,the fault pattern can be identified by matching the prominent peaks in the demodulation spectrum with the theoretical characteristic frequencies.The method is validated by simulated and experimental signals.展开更多
Abstract: In order to solve the problem of high precision, complete electric insulating detection of the pressure measuring system, we have developed the three - beam interferometer. In this paper, the operation princ...Abstract: In order to solve the problem of high precision, complete electric insulating detection of the pressure measuring system, we have developed the three - beam interferometer. In this paper, the operation principle, structure of the system and measuring results are given.展开更多
文摘The structure,equivalent circuit,noise sources of silicon photodiode are analyzed.In order to improve the measuring linearity,we must choose the silicon photodiode with a large R d,small R s and I 0 and under an operation state of output short-circuit.We must let the operation amplifier work in the current-voltage transfer form.Also we analyzed the effects of the input noise voltage,the input noise current,the input offset voltage,the input offset current of the operation amplifier and the noises of the silicon photodiode on the combined circuit of the operation amplifier with the silicon photodiode.Considering these factors,we can design the detective circuit with high response,sensitivity,stability,linearity and SNR .
文摘Transmission of oesophageal images may vary between different small-bowel capsule endoscopy models. A retrospective review of 100 examinations performed with 2 different Small-bowel capsule endoscopy （SBCE） sys- tems （PillCam and MiroCam） was performed. The oral cavity/aero-digestive tract （i.e., tongue, uvula and/or epiglottis） was captured/identified in almost all （99%） of PillCam videos but in none of MiroCam cases, P 〈 0.0001. Furthermore, oesophageal images （i.e., from the upper oesophageal sphincter to the Z-line were cap- tured in 99% of PillCam videos （mean =1= SD, 60.5 ± 334.1 frames, range： 0-3329 frames） and in 66% of Mi- roCam cases （mean ± SD, 11.1 ± 46.5 frames, range： 0-382 frames）, P 〈 0.0001. The Z-line was identified in 42% of PilICam videos and 17% of MiroCam, P = 0.0002. This information might be useful when perform- ing SBCE in patients with high risks for aspiration.
基金Project(2018YJS137)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(51275030)supported by the National Natural Science Foundation of China
文摘The vibration signals of multi-fault rolling bearings under nonstationary conditions are characterized by intricate modulation features,making it difficult to identify the fault characteristic frequency.To remove the time-varying behavior caused by speed fluctuation,the phase function of target component is necessary.However,the frequency components induced by different faults interfere with each other.More importantly,the complex sideband clusters around the characteristic frequency further hinder the spectrum interpretation.As such,we propose a demodulation spectrum analysis method for multi-fault bearing detection via chirplet path pursuit.First,the envelope signal is obtained by applying Hilbert transform to the raw signal.Second,the characteristic frequency is extracted via chirplet path pursuit,and the other underlying components are calculated by the characteristic coefficient.Then,the energy factors of all components are determined according to the time-varying behavior of instantaneous frequency.Next,the final demodulated signal is obtained by iteratively applying generalized demodulation with tunable E-factor and then the band pass filter is designed to separate the demodulated component.Finally,the fault pattern can be identified by matching the prominent peaks in the demodulation spectrum with the theoretical characteristic frequencies.The method is validated by simulated and experimental signals.
文摘Abstract: In order to solve the problem of high precision, complete electric insulating detection of the pressure measuring system, we have developed the three - beam interferometer. In this paper, the operation principle, structure of the system and measuring results are given.
