The first laboratory of electromagnetic compatibility in Chinais possessed of vivid characteristics in respect of design and configurationof testing equipment. It has successively completed some testing projectsand wi...The first laboratory of electromagnetic compatibility in Chinais possessed of vivid characteristics in respect of design and configurationof testing equipment. It has successively completed some testing projectsand will unfold a more extensive range of measurement and test works inthe days to come.[展开更多
Due to the strong electromagnetic interferences and human interference,traditional electromagnetic methods cannot obtain high quality resistivity data of mineral deposits in Chinese mines.The wide field electromagneti...Due to the strong electromagnetic interferences and human interference,traditional electromagnetic methods cannot obtain high quality resistivity data of mineral deposits in Chinese mines.The wide field electromagnetic method(WFEM),in which the pseudo-random signal is taken as the transmitter source,can extract high quality resistivity data in areas with sever interference by only measuring the electric field component.We use the WFEM to extract the resistivity information of the Dongguashan mine in southeast China.Compared with the audio magnetotelluric(AMT)method,and the controlled source audio-frequency magnetotelluric(CSAMT) method,the WFEM can obtain data with higher quality and simpler operations.The inversion results indicate that the WFEM can accurately identify the location of the main ore-body,which can be used for deep mine exploration in areas with strong interference.展开更多
The active reflector of FAST （ five-hundred-meter aperture spherical radio telescope） is suppor- ted by a ring beam and a cable-net structure, in which nodes are actively controlled to form series of real-time parab...The active reflector of FAST （ five-hundred-meter aperture spherical radio telescope） is suppor- ted by a ring beam and a cable-net structure, in which nodes are actively controlled to form series of real-time paraboloids. To ensure the security and stability of the supporting structure, tension must be monitored for some typical cables. Considering the stringent requirements in accuracy and long- term stability, magnetic flux sensor, vibrating wire strain gauge and fiber bragg grating strain gauge are screened for the cable tension monitoring of the supporting cable-net. Specifically, receivers of radio telescopes have strict restriction on electro magnetic interference （EMI） or radio frequency in- terference （RFI）. These three types of sensors are evaluated from the view of EMIfRFI. Firstly, these fundamentals are theoretically analyzed. Secondly, typical sensor signals are collected in the time and analyzed in the frequency domain, which shows the characteristic in the frequency domain. Finally, typical sensors are tested in an anechoic chamber to get the EMI levels. Theoretical analysis shows that Fiber Bragg Grating strain gauge itself will not lead to EMI/RFI. According to GJB151 A, frequency domain analysis and test results show that for the vibrating wire strain gauge and magnetic flux sensor themselves, testable EMIfRF1 levels are typically below the background noise of the ane- choic chamber. FAST finally choses these three sensors as the monitoring sensors of its cable ten- sion. The proposed study is also a reference to the monitoring equipment selection of other radio tele- scopes and large structures.展开更多
文摘The first laboratory of electromagnetic compatibility in Chinais possessed of vivid characteristics in respect of design and configurationof testing equipment. It has successively completed some testing projectsand will unfold a more extensive range of measurement and test works inthe days to come.[
基金Project(2018YFC0807802)supported by the National Key R&D Program of ChinaProject(41874081)supported by the National Natural Science Foundation of China
文摘Due to the strong electromagnetic interferences and human interference,traditional electromagnetic methods cannot obtain high quality resistivity data of mineral deposits in Chinese mines.The wide field electromagnetic method(WFEM),in which the pseudo-random signal is taken as the transmitter source,can extract high quality resistivity data in areas with sever interference by only measuring the electric field component.We use the WFEM to extract the resistivity information of the Dongguashan mine in southeast China.Compared with the audio magnetotelluric(AMT)method,and the controlled source audio-frequency magnetotelluric(CSAMT) method,the WFEM can obtain data with higher quality and simpler operations.The inversion results indicate that the WFEM can accurately identify the location of the main ore-body,which can be used for deep mine exploration in areas with strong interference.
基金Supported by the National Natural Science Foundation of China(No.11173035,11273036,11303059)
文摘The active reflector of FAST （ five-hundred-meter aperture spherical radio telescope） is suppor- ted by a ring beam and a cable-net structure, in which nodes are actively controlled to form series of real-time paraboloids. To ensure the security and stability of the supporting structure, tension must be monitored for some typical cables. Considering the stringent requirements in accuracy and long- term stability, magnetic flux sensor, vibrating wire strain gauge and fiber bragg grating strain gauge are screened for the cable tension monitoring of the supporting cable-net. Specifically, receivers of radio telescopes have strict restriction on electro magnetic interference （EMI） or radio frequency in- terference （RFI）. These three types of sensors are evaluated from the view of EMIfRFI. Firstly, these fundamentals are theoretically analyzed. Secondly, typical sensor signals are collected in the time and analyzed in the frequency domain, which shows the characteristic in the frequency domain. Finally, typical sensors are tested in an anechoic chamber to get the EMI levels. Theoretical analysis shows that Fiber Bragg Grating strain gauge itself will not lead to EMI/RFI. According to GJB151 A, frequency domain analysis and test results show that for the vibrating wire strain gauge and magnetic flux sensor themselves, testable EMIfRF1 levels are typically below the background noise of the ane- choic chamber. FAST finally choses these three sensors as the monitoring sensors of its cable ten- sion. The proposed study is also a reference to the monitoring equipment selection of other radio tele- scopes and large structures.
