Last data update: Apr 22, 2024. (Total: 46599 publications since 2009)
Records 1-12 (of 12 Records) |
Query Trace: Jacksha R [original query] |
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Smart monitoring and control system test apparatus
Raj KV , Jacksha RD , Sunderman CB , Pritchard CJ . Trans Soc Min Metall Explor Inc 2018 344 (1) 62-66 In underground metal/nonmetal mines, repeated localized short-term exposure to high levels of airborne contaminants can become a serious health issue. Currently, there are no common mechanisms to control or mitigate these short-term high exposures to contaminants. To improve miners' health and safety, the U.S. National Institute for Occupational Safety and Health's Spokane Mining Research Division (SMRD) is developing a smart monitoring and control (SMAC) system for the real-time monitoring of mine air quality, with integrated countermeasures to reduce high concentrations of airborne contaminants in localized sections of mines. To develop and test a SMAC system capable of being implemented in an underground mine, SMRD researchers built a test apparatus incorporating a fan, louver, ducting and sensors combined with atmospheric monitoring and control software. This system will institute effective countermeasures to reduce contaminant levels, improving miner safety and health. |
Assessing the feasibility of a commercially available wireless Internet of Things system to improve conveyor safety
Jacksha R , Raj KV . Min Metall Explor 2020 38 567-574 Conveyor systems persist in being a source of injuries and fatalities in the mining industry. To reduce these incidents, better methods are needed to enhance the monitoring of probable hazards and improve situational awareness during the normal operation and maintenance of conveyor systems. To address these issues, researchers from the National Institute for Occupational Safety and Health (NIOSH) continue to investigate emerging technologies that show the potential to improve miner safety around conveyors. This paper presents a feasibility assessment by NIOSH researchers of a fully integrated, commercially available wireless Internet of Things (IoT) system to improve situational awareness around conveyor systems. Included are discussions of a full-scale laboratory test bed that was designed to simulate a working conveyor system as well as the challenges and successes of integrating the IoT system with the test bed. |
Measurement of the influence of antennas on radio signal propagation in underground mines and tunnels
Jacksha R , Zhou C , Sunderman C . Prog Electromagn Res C 2019 94 1-12 This paper reports the influence of antennas on radio signal propagation in tunnels and underground mines. Radio signal propagation measurement results in a concrete tunnel and underground mines using antenna types with various radiation patterns, i.e., omnidirectional, Yagi, patch, and circular, are reported. Extensive measurements were taken in various scenarios which include vertical, horizontal, and circular polarization for line-of-sight (LoS) radio signal propagation at four frequencies (455, 915, 2450, and 5800 MHz) that are common to many voice and data transport radio systems used in underground mines. The results show that antenna pattern has a strong influence on the uniformity of radio signal propagation gain in the near zone and typically does not significantly influence behavior in the far zone, except for a constant gain offset. |
Leveraging IIoT to improve machine safety in the mining industry
McNinch M , Parks D , Jacksha R , Miller A . Min Metall Explor 2019 36 (4) [Epub ahead of print] Each year, hundreds of mine workers are involved in machinery-related accidents. Many of these accidents involve inadequate or improper use of lockout/tagout (LOTO) procedures. To mitigate the occurrence of these accidents, new safety methods are needed to monitor access to hazardous areas around operating machinery, improve documentation/monitoring of maintenance that requires shutdown of the machinery, and prevent unexpected startup or movement during machine maintenance activities. The National Institute for Occupational Safety and Health (NIOSH) is currently researching the application of Internet of Things (IoT) technologies to provide intelligent machine monitoring as part of a comprehensive LOTO program. This paper introduces NIOSH's two phase implementation of an IoT-based intelligent machine monitoring system. Phase one is the installation of a proof-of-concept system at a concrete batch plant, while phase two involves scaling up the system to include additional sensors, more detailed safety/performance metrics, proximity detection, and predictive failure analysis. |
Intelligent monitoring system for improved worker safety during plant operation and maintenance
Parks D , McNinch M , Jacksha R , Nickerson H , Miller A . Min Eng 2019 71 (3) 34-38 Each year hundreds of mine workers are involved in machinery-related accidents. Many of these accidents involve inadequate or improper use of lockout/tagout (LOTO) procedures. To mitigate the occurrence of these accidents, new safety methods are needed to monitor access to hazardous areas around operating machinery, improve documentation/monitoring of maintenance that requires shutdown of the machinery, and prevent unexpected startup or movement during machine maintenance activities. The U.S. National Institute for Occupational Safety and Health (NIOSH) is currently researching the application of Internet of Things (IoT) technologies to provide intelligent machine monitoring as part of a comprehensive LOTO program. This paper introduces NIOSH’s implementation of an IoT-based intelligent machine monitoring system to improve safety during operation and maintenance at a concrete batch plant. |
Data transport over leaky feeder systems using Internet-Protocol-enabled land mobile radios
Jacksha R , Sunderman C . Min Eng 2018 70 (12) 44-47 Mine monitoring through various sensors is a vital component of successful miner safety and health programs. Data from environmental, geotechnical, infrastructure and other types of sensors are increasingly used to discover and mitigate health and safety concerns in underground mines. In many smaller underground mines, as well as in the new development headings of larger underground mines, leaky feeder communication systems may be the only available means to transport crucial monitoring data. In addition, data transport is increasingly being delivered using Internet Protocol (IP), while older forms of serial communication are being retired. This paper presents the selection, configuration and testing methodologies employed by researchers from the U.S. National Institute for Occupational Safety and Health (NIOSH) to integrate commercially available land mobile data radios into an existing leaky feeder communication system to provide IP data transport. |
Time domain and frequency domain deterministic channel modeling for tunnel/mining environments
Zhou C , Jacksha R , Yan L , Reyes M , Kovalchik P . Prog Electromagn Res C Pier C 2017 79 209-223 Understanding wireless channels in complex mining environments is critical for designing optimized wireless systems operated in these environments. In this paper, we propose two physicsbased, deterministic ultra-wideband (UWB) channel models for characterizing wireless channels in mining/tunnel environments one in the time domain and the other in the frequency domain. For the time domain model, a general Channel Impulse Response (CIR) is derived and the result is expressed in the classic UWB tapped delay line model. The derived time domain channel model takes into account major propagation controlling factors including tunnel or entry dimensions, frequency, polarization, electrical properties of the four tunnel walls, and transmitter and receiver locations. For the frequency domain model, a complex channel transfer function is derived analytically. Based on the proposed physics-based deterministic channel models, channel parameters such as delay spread, multipath component number, and angular spread are analyzed. It is found that, despite the presence of heavy multipath, both channel delay spread and angular spread for tunnel environments are relatively smaller compared to that of typical indoor environments. The results and findings in this paper have application in the design and deployment of wireless systems in underground mining environments. 2017, Electromagnetics Academy. All rights reserved. |
Modeling and measurement of radio propagation in tunnel environments
Zhou C , Jacksha R . IEEE Antennas Wirel Propag Lett 2017 16 141-144 A simple radio frequency (RF) testing system that can be conveniently built and used for measuring radio propagation in tunnels is introduced. With the proposed testing system, RF power attenuation with distance in a train tunnel was measured at four frequencies (455, 915, 2450, and 5800 MHz) for both horizontal and vertical polarizations. Two analytical modeling methods-the ray tracing and modal methods-are applied to model RF propagation in the tunnel. The theoretical predictions based on both methods are compared to field measurements and find good agreement. |
Measurement of RF propagation around corners in underground mines and tunnels
Jacksha R , Zhou C . Trans Soc Min Metall Explor Inc 2016 340 (1) 30-37 This paper reports measurement results for radio frequency (RF) propagation around 90° corners in tunnels and underground mines, for vertically, horizontally and longitudinally polarized signals. Measurements of signal power attenuation from a main entry into a crosscut were performed at four frequencies - 455, 915, 2450 and 5800 MHz - that are common to underground radio communication systems. From the measurement data, signal power loss was determined as a function of signal coupling from the main entry into the crosscut. The resultant power loss data show there are many factors that contribute to power attenuation from a main entry into a crosscut, including frequency, antenna polarization and cross-sectional entry dimensions. |
Measurement and modeling of radio propagation from a primary tunnel to cross junctions
Zhou C , Jacksha R , Reyes M . Proc IEEE Radio Wirel Symp 2016 2016 70-72 In this paper, we propose a new model for predicting around-corner coupling loss associated with radio signals propagating from a primary tunnel to cross junctions. The proposed model is based on the classic modal method that has been widely used for predicting power distribution in straight tunnels. The uniform theory of diffraction (UTD) is applied to calculate mode coupling coefficients. Simulation results based on the proposed model are compared to measurement results taken in a concrete tunnel and show good agreement. |
A review of underground coal mine emergency communications and tracking system installations
Damiano N , Homce G , Jacksha R . Coal Age 2014 119 (11) 34-35 The 2006 Mine Improvement and New Emergency Response Act of 2006 (MINER Act) required all underground coal mines in the U.S. to have a plan to provide post-accident communication and electronic tracking for any mine workers trapped underground. | In response, post-accident communications and electronic tracking (emergency CT) technologies designed to meet MINER Act requirements have been developed by various manufacturers and approved for permissibility by the Mine Safety and Health Administration (MSHA), meaning they may be used safely in coal mines that may have gassy or dust-laden atmospheres. As a result, more than a dozen different emergency CT systems have become available for U.S. underground coal mining. | The National Institute for Occupational Safety and Health (NIOSH) recently conducted a review of the latest MSHA-approved Emergency Response Plans (ERPs) for each active underground coal mine on file as of February 2014 to identify and characterize the types of emergency CT systems installed. This review pertains only to CT systems installed underground for emergency purposes, and does not include any CT systems installed or used for non-emergency situations, such as communications for everyday operations. |
Attenuation constants of radio waves in lossy-walled rectangular waveguides
Zhou C , Waynert J , Plass T , Jacksha R . Prog Electromagn Res 2013 142 75-105 At the ultra-high frequencies (UHF) common to portable radios, the mine tunnel acts as a dielectric waveguide, directing and absorbing energy as a radio signal propagates. Understanding radio propagation behavior in a dielectric waveguide is critical for designing reliable, optimized communication systems in an underground mine. One of the major parameters used to predict the power attenuation in lossy waveguides is the attenuation constant. In this paper, we theoretically and experimentally investigate the attenuation constants for a rectangular waveguide with dielectric walls. We provide a new derivation of the attenuation constant based on the classic Fresnel reflection coefficients. The new derivation takes advantage of ray representation of plane waves and provides more insight into understanding radio attenuation in tunnels. We also investigate the impact of different parameters on the attenuation constant, including the tunnel transverse dimensions, permittivity, conductivity, frequency, and polarization, with an aim to find their theoretical optimal values that result in the minimum power loss. Additionally, measurements of the attenuation constants of the dominant mode at different frequencies (455, 915, 2450, and 5800 MHz) for a straight concrete tunnel are presented and compared to theoretical predictions. It is shown that the analytical results match the measured results very well at all four frequencies. |
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