Last data update: May 13, 2024. (Total: 46773 publications since 2009)
Records 1-4 (of 4 Records) |
Query Trace: Whisner BG[original query] |
---|
Influence of steel mesh on magnetic proximity detection systems: An experimental study
Zhou C , Whisner BG , Carr JL , Srednicki J . Prog Electromagn Res M Pier M 2020 90 89-97 Proximity Detection Systems (PDSs) are used in the mining industry for protecting mine workers from striking, pinning, and crushing injuries when they work in close proximity to heavy machines such as continuous mining machines (CMMs). Currently all PDSs approved by the Mine Safety and Health Administration (MSHA) are magnetic field based systems which can be influenced by the presence of steel wire mesh that is commonly used for supporting roof and ribs in underground coal mines. In this paper, researchers at the National Institute for Occupational Safety and Health (NIOSH) characterized the influence of the mesh on the performance of magnetic PDSs by measuring the magnetic field difference around a CMM caused by the presence of the mesh. The results show that the magnetic fields are generally enhanced by the mesh which causes PDS detection zones to be increased correspondingly. It was discovered that the fields around the joints of two mesh sections have the greatest enhancement and thus deserve more attention. In addition, it was found that the presence of mesh can also cause a variation in the generator current. The experimental results show that the generator current variation and thus the magnetic field change caused by the mesh can be significant (on the order of ten) when the mesh is extremely close to the generator (e.g., less than 1 cm) and is negligible when mesh is relatively far (greater than 0.15 m). The findings in this paper can be used to develop guidelines and best practices to mitigate the influence of mesh on PDSs. |
Medium-frequency signal propagation characteristics of a lifeline as a transmission line in underground coal mines
Li J , Reyes MA , Damiano NW , Whisner BG , Matetic RJ . IEEE Trans Ind Appl 2016 52 (3) 2724-2730 Underground coal mines in the United States of America are required to install lifeline (LL) cable inside escapeways to guide miners out of a mine when visibility becomes poor due to heavy smoke. Some LLs consist of single or multiple steel conductors covered with a protective plastic outer layer. Research has shown that this type of LL can be a good conductor to guide a medium-frequency (MF) communication system signal to travel over large distances. To understand the MF propagation characteristics of an LL, National Institute for Occupational Safety and Health researchers took measurements on a section of LL in a coal mine, and obtained propagation parameters for analysis. The measurement data show that MF signals have a low attenuation which can enable the use of an LL for communication throughout a mine. The propagation parameters measured are presented in this paper. © 2016 IEEE. |
Medium frequency propagation characteristics of different transmission lines in an underground coal mine
Li J , Waynert JA , Whisner BG . Int J Commun Antenna Propag 2015 5 (1) 7-15 A medium frequency (MF) communication system operating in an underground coal mine couples its signals to a long conductor, which acts as an MF transmission line (TL) in a tunnel to permit communications among transceivers along the line. The TL is generally the longest signal path for the system, and its propagation characteristics will have a major impact on the performance of the MF communication system. In this study, the propagation characteristics of three types of MF TLs in two layouts-on the roof and on the floor of a coal mine tunnel-were obtained in an effort to understand the propagation characteristics of different TLs in different locations. The study confirmed a low MF signal loss on all of these TLs. The study also found that the TLs in different layouts had substantially different propagation characteristics. The propagation characteristics of these different TLs in different layouts are presented in the paper. |
An introduction to a medium frequency propagation characteristic measurement method of a transmission line in underground coal mines
Li J , Waynert JA , Whisner BG . Prog Electromagn Res B Pier B 2013 55 (55) 131-149 An underground coal mine medium frequency (MF) communication system generally couples its electromagnetic signals to a long conductor in a tunnel, which acts as a transmission line, and exchanges signals with transceivers along the line. The propagation characteristics of the transmission line, which is usually the longest signal path for an MF communication system, play a major role in determining the system performance. To measure the MF propagation characteristics of transmission lines in coal mine tunnels, a method was developed based on a basic transmission line model. The method will be presented in this paper along with the propagation measurements on a transmission line system in a coal mine using the method. The measurements con-rmed a low MF signal power loss rate, and showed the influence of the electrical properties of surrounding coal and rock on the MF propagation characteristics of the line. |
- Page last reviewed:Feb 1, 2024
- Page last updated:May 13, 2024
- Content source:
- Powered by CDC PHGKB Infrastructure