The use of in-seam waves for void detection in mines requires the capability of capturing high frequency signals over large distances. For instance, the Airy phase of Love waves which are used for void detection in co...The use of in-seam waves for void detection in mines requires the capability of capturing high frequency signals over large distances. For instance, the Airy phase of Love waves which are used for void detection in coal mines ranges from several hundred to over one thousand Hertz and the expected travel distance of these signals is at least 90 m （equivalent to a detection distance of 45 m） for the technique to be considered practical. In order to obtain high quality and broadband signals, sensors are conventionally grouted at the bottom of boreholes so that the attenuation due to the fractured surface is minimized and the coupling effect is improved. However, to be economically feasible, the expensive and high sensitive sensors must be retrievable so that they can be used repeatedly at the same or other locations. Because of these concerns, a retrievable sensor installation technique was developed. This paper provides a detailed review of the technique as well as a brief discussion of its applications. The technique is simple and reliable for both installation and retrieval operations and can be used for boreholes oriented in any directions. The technique has been demonstrated in over 200 sensor installation/retrieval operations under various borebole conditions, including bituminous coal, anthracite coal, shale, sandstone and trona. With this technique, we were able to detect the high frequency signals required for our projects. For instance, the signals used at a trona mine for void detection have a typical frequency of 5 kHz with the travel distance of 150-200 m. The results of these operations have shown that sensors installed in the prescribed manner exhibit predictable, consistent, and repeatable performance. The technique also provides an economical and reliable means for many other field seismic monitoring applications where high quality and broadband signals are essential, such as microseismic monitoring and geotomography studies.展开更多
The integrated strap-down inertial nav igation system/olelestial navigation system(SINS/CNS)i an important autonomous navigation method with efective concealment and high predision.Both accelerometer biss and star ens...The integrated strap-down inertial nav igation system/olelestial navigation system(SINS/CNS)i an important autonomous navigation method with efective concealment and high predision.Both accelerometer biss and star ensor installation error ame important factors that aflect the performanoe of this mavigation system,which needl to be calibratexd and compensatedl.A new acelerometer bias and star sensor installation error joint calibration method for the SINS/CNS integrated navigation system i propoeed.In this newly propoeed method,the installation error of star sensor is augmented to the state vector,and the star vector,nadir angle,horkzontal poeition error and velbcity error ame ueed a8 measurementa to calbrate the two errors mentioned above.Simulations show that both accelerometer bias and star sensor installation enror an be calibratedl efectively.展开更多
When a pig mounted with permanent magnets gets stuck in the pipeline,it can be located by detecting the magnetic anomalies on the ground using a single-axis magnetic sensor.In order to collect the magnetic anomaly eff...When a pig mounted with permanent magnets gets stuck in the pipeline,it can be located by detecting the magnetic anomalies on the ground using a single-axis magnetic sensor.In order to collect the magnetic anomaly efficiently through single-axis magnetic sensor,a geometric detection model and calculation method for singleaxis magnetic anomaly detection is established in this paper.The distribution of magnetic inclination and declination of the measuring points is obtained.The results indicate that the magnetic inclination of all measuring points vary within a small range of 2°,and this value is highly dependent on the magnetic sensor which is configured aboveground around the geomagnetic inclination.However,the magnetic declination at different points of detection surface is subject to the geomagnetic components and the Y-axis component of the magnetic field of magnets.The magnetic declinations distribute irregularly and vary in a wide range.Therefore,to achieve a high-efficiency detection with the single-axis sensor,the sensor shall be placed in such a manner that the magnetic inclination thereof coincides with the geomagnetic inclination.The magnetic declination of the sensor can be calculated using s,the superposed Y-axis component induced by the permanent magnets,and the corresponding formula given in this paper.The article demonstrates the feasibility of locating a blocked pig in the pipeline based on the single-axis magnetic anomaly detection.It will have a practical significance in guiding the engineering detection.展开更多
基金Supported by the Mine Safety and Health Administration (MSHA) Project in US (B2532532)
文摘The use of in-seam waves for void detection in mines requires the capability of capturing high frequency signals over large distances. For instance, the Airy phase of Love waves which are used for void detection in coal mines ranges from several hundred to over one thousand Hertz and the expected travel distance of these signals is at least 90 m （equivalent to a detection distance of 45 m） for the technique to be considered practical. In order to obtain high quality and broadband signals, sensors are conventionally grouted at the bottom of boreholes so that the attenuation due to the fractured surface is minimized and the coupling effect is improved. However, to be economically feasible, the expensive and high sensitive sensors must be retrievable so that they can be used repeatedly at the same or other locations. Because of these concerns, a retrievable sensor installation technique was developed. This paper provides a detailed review of the technique as well as a brief discussion of its applications. The technique is simple and reliable for both installation and retrieval operations and can be used for boreholes oriented in any directions. The technique has been demonstrated in over 200 sensor installation/retrieval operations under various borebole conditions, including bituminous coal, anthracite coal, shale, sandstone and trona. With this technique, we were able to detect the high frequency signals required for our projects. For instance, the signals used at a trona mine for void detection have a typical frequency of 5 kHz with the travel distance of 150-200 m. The results of these operations have shown that sensors installed in the prescribed manner exhibit predictable, consistent, and repeatable performance. The technique also provides an economical and reliable means for many other field seismic monitoring applications where high quality and broadband signals are essential, such as microseismic monitoring and geotomography studies.
文摘The integrated strap-down inertial nav igation system/olelestial navigation system(SINS/CNS)i an important autonomous navigation method with efective concealment and high predision.Both accelerometer biss and star ensor installation error ame important factors that aflect the performanoe of this mavigation system,which needl to be calibratexd and compensatedl.A new acelerometer bias and star sensor installation error joint calibration method for the SINS/CNS integrated navigation system i propoeed.In this newly propoeed method,the installation error of star sensor is augmented to the state vector,and the star vector,nadir angle,horkzontal poeition error and velbcity error ame ueed a8 measurementa to calbrate the two errors mentioned above.Simulations show that both accelerometer bias and star sensor installation enror an be calibratedl efectively.
基金This work is supported by the National Natural Science Foundation of China under Grant No.41374151the Sichuan Province Applied Basic Research Project(No.2017JY0162)the Young Scholars Development Fund of SWPU(No.201599010079).
文摘When a pig mounted with permanent magnets gets stuck in the pipeline,it can be located by detecting the magnetic anomalies on the ground using a single-axis magnetic sensor.In order to collect the magnetic anomaly efficiently through single-axis magnetic sensor,a geometric detection model and calculation method for singleaxis magnetic anomaly detection is established in this paper.The distribution of magnetic inclination and declination of the measuring points is obtained.The results indicate that the magnetic inclination of all measuring points vary within a small range of 2°,and this value is highly dependent on the magnetic sensor which is configured aboveground around the geomagnetic inclination.However,the magnetic declination at different points of detection surface is subject to the geomagnetic components and the Y-axis component of the magnetic field of magnets.The magnetic declinations distribute irregularly and vary in a wide range.Therefore,to achieve a high-efficiency detection with the single-axis sensor,the sensor shall be placed in such a manner that the magnetic inclination thereof coincides with the geomagnetic inclination.The magnetic declination of the sensor can be calculated using s,the superposed Y-axis component induced by the permanent magnets,and the corresponding formula given in this paper.The article demonstrates the feasibility of locating a blocked pig in the pipeline based on the single-axis magnetic anomaly detection.It will have a practical significance in guiding the engineering detection.
