Transient electromagnetic method (TEM),as a non-seismic geophysical exploration mainstream electromagnetic method,is widely used in oil,gas,mineral and other underground resources exploration areas. The coil sensor is...Transient electromagnetic method (TEM),as a non-seismic geophysical exploration mainstream electromagnetic method,is widely used in oil,gas,mineral and other underground resources exploration areas. The coil sensor is generally used to collect data. In view of the problems of incomplete information of the abnormal body and the data loss in the existing TEM single-component coil sensor,a three-component TEM coil sensor is designed. By analyzing the relationship between sensor sensitivity and coil structure parameters,the coil structure and turns are designed. By analyzing the frequency response characteristics of the TEM magnetic field sensor,the signal distortion is reduced by using the under-damped matching mode. By analyzing the distribution of various noise sources of the magnetic sensor,the appropriate amplifier is selected to reduce the background noise. Finally,a three-component TEM induction magnetic field sensor is designed. The weight of the sensor is controlled at 3.2 kg and the working frequency is 10 mHz-10 kHz. The background noises of X and Y components probably keep in 1.5×10^-8 V/ Hz and sensitivities are 8.4 and 9.8 nT/s,respectively,the background noise of vertical component is 2.1× 10^-7 V/ Hz and sensitivity is 18.5 nT/s. Compared with the existing single-component TEM receiving magnetic field sensor,the designed sensor realizes the signal acquisition of three components. Without too much increase in volume and total weight,it improves the sensitivity of the sensor and reduces the background noise,thus the signal-to-noise ratio (SNR) of the signal is improved.展开更多
Electromagnetic forming （EMF） is a high velocity forming process that uses impulse magnetic force. Coil is an important component of EMF system which needs to be designed depending on application. Flat spiral coils ...Electromagnetic forming （EMF） is a high velocity forming process that uses impulse magnetic force. Coil is an important component of EMF system which needs to be designed depending on application. Flat spiral coils are generally used for electromagnetic forming of sheet metals. However, with this type of coil the central portion of the workpiece experiences marginal magnetic force. This leads to in-sufficient deformation at this portion and other problems like air entrapment. In this study, a conceptual design of flat coil was proposed for better distribution of magnetic forces over the workpiece. Comparative analysis of distribution of magnetic force, magnetic field and current density using the proposed and the existing coil designs were carried out using FEM. The result indicates that the proposed coil design produces comparatively better magnetic force distribution over the workpiece. Calculation of self-inductance of such coils was also carried out and was compared with FE simulation.展开更多
Magnetometric resistivity(MMR)method is a new way to detect dam leakage.The coil sensor is generally used to collect data in geophysical exploration methods.Given the characteristics of accurate vector data requiremen...Magnetometric resistivity(MMR)method is a new way to detect dam leakage.The coil sensor is generally used to collect data in geophysical exploration methods.Given the characteristics of accurate vector data requirements and high sensitivity requirement,a three-component MMR air-core coil sensor is designed.Through the analysis of sensor sensitivity and coil structure parameters,the coil structure and turn number are designed.By analyzing the noise source of the sensor,a suitable amplifier is selected to reduce the background noise of the system.Through the analysis of the three-component non-orthogonal angles,the parameters of the non-orthogonal angles of the coils are corrected.Finally,a three-component MMR induction magnetic field sensor is designed.The volume of the sensor is controlled at 0.027 m 3.The background noise of X、Y and Z are 5.030435 nV/Hz@380 Hz and magnetic field sensitivities are 0.18995 pT/Hz@380 Hz.The three channels have good consistency,and the three-component nonorthogonal angles correction error of three components is controlled within 0.2%.展开更多
文摘Transient electromagnetic method (TEM),as a non-seismic geophysical exploration mainstream electromagnetic method,is widely used in oil,gas,mineral and other underground resources exploration areas. The coil sensor is generally used to collect data. In view of the problems of incomplete information of the abnormal body and the data loss in the existing TEM single-component coil sensor,a three-component TEM coil sensor is designed. By analyzing the relationship between sensor sensitivity and coil structure parameters,the coil structure and turns are designed. By analyzing the frequency response characteristics of the TEM magnetic field sensor,the signal distortion is reduced by using the under-damped matching mode. By analyzing the distribution of various noise sources of the magnetic sensor,the appropriate amplifier is selected to reduce the background noise. Finally,a three-component TEM induction magnetic field sensor is designed. The weight of the sensor is controlled at 3.2 kg and the working frequency is 10 mHz-10 kHz. The background noises of X and Y components probably keep in 1.5×10^-8 V/ Hz and sensitivities are 8.4 and 9.8 nT/s,respectively,the background noise of vertical component is 2.1× 10^-7 V/ Hz and sensitivity is 18.5 nT/s. Compared with the existing single-component TEM receiving magnetic field sensor,the designed sensor realizes the signal acquisition of three components. Without too much increase in volume and total weight,it improves the sensitivity of the sensor and reduces the background noise,thus the signal-to-noise ratio (SNR) of the signal is improved.
文摘Electromagnetic forming （EMF） is a high velocity forming process that uses impulse magnetic force. Coil is an important component of EMF system which needs to be designed depending on application. Flat spiral coils are generally used for electromagnetic forming of sheet metals. However, with this type of coil the central portion of the workpiece experiences marginal magnetic force. This leads to in-sufficient deformation at this portion and other problems like air entrapment. In this study, a conceptual design of flat coil was proposed for better distribution of magnetic forces over the workpiece. Comparative analysis of distribution of magnetic force, magnetic field and current density using the proposed and the existing coil designs were carried out using FEM. The result indicates that the proposed coil design produces comparatively better magnetic force distribution over the workpiece. Calculation of self-inductance of such coils was also carried out and was compared with FE simulation.
文摘Magnetometric resistivity(MMR)method is a new way to detect dam leakage.The coil sensor is generally used to collect data in geophysical exploration methods.Given the characteristics of accurate vector data requirements and high sensitivity requirement,a three-component MMR air-core coil sensor is designed.Through the analysis of sensor sensitivity and coil structure parameters,the coil structure and turn number are designed.By analyzing the noise source of the sensor,a suitable amplifier is selected to reduce the background noise of the system.Through the analysis of the three-component non-orthogonal angles,the parameters of the non-orthogonal angles of the coils are corrected.Finally,a three-component MMR induction magnetic field sensor is designed.The volume of the sensor is controlled at 0.027 m 3.The background noise of X、Y and Z are 5.030435 nV/Hz@380 Hz and magnetic field sensitivities are 0.18995 pT/Hz@380 Hz.The three channels have good consistency,and the three-component nonorthogonal angles correction error of three components is controlled within 0.2%.
