Last data update: May 13, 2024. (Total: 46773 publications since 2009)
Records 1-3 (of 3 Records) |
Query Trace: Jobes CC[original query] |
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Assessment of whole-body vibration exposures and influencing factors for quarry haul truck drivers and loader operators
Mayton AG , Jobes CC , Gallagher S . Int J Heavy Veh Syst 2014 21 (3) 241-261 To further assess vibration exposure on haul trucks (HTs) and front-end wheel loaders (FELs), follow-up investigations were conducted at two US crushed stone operations. The purpose was to: 1) evaluate factors such as load/no-load conditions, speed, load capacity, vehicle age, and seat transmissibility relative to vibration exposure; 2) compare exposure levels with existing ISO/ANSI and EUGPG guidelines. Increasing HT speed increased recorded vibration at the chassis and seat as expected. Neither vehicle load nor vehicle speed increased transmissibility. Increasing HT size and age did show transmissibility decreasing. HT dominant-axis wRMS levels (most often the y-axis, lateral or side-to-side direction) were predominantly within the health guidance caution zone (HGCZ). However, several instances showed vibration dose value (VDV) above the exposure limit value (ELV) for the ISO/ANSI guidelines. VDV levels (all dominant x-axis or fore-aft) were within and above the HGCZ for the EUGPG and above the HGCZ for ISO/ANSI guidelines. |
Comparison of magnetic field distribution models for a magnetic proximity detection system
Li J , Jobes CC , Carr JL . IEEE Trans Ind Appl 2013 49 (3) 1171-1176 Magnetic proximity detection technology is rapidly advancing as a promising method of protecting underground mine workers from striking and pinning hazards associated with mobile mining machines. A magnetic proximity detection system requires a magnetic distribution model to estimate the proximity of the sensor to the generators. This paper presents a comparative analysis of magnetic flux density distribution models in three different field distribution design patterns. The accuracy of these models is determined with a laboratory magnetic proximity detection system. These field distribution design patterns are spherical, ellipsoidal, and sphere-cosine, respectively. The analyses show that the sphere-cosine model is the most accurate model for the proximity system followed by the ellipsoidal and spherical models. |
Whole-body vibration exposure comparison of seat designs for low- and mid-seam shuttle cars in underground coal mines
Mayton AG , Jobes CC , Ambrose DH , Kittusamy NK . Trans Soc Min Metall Explor Inc 2010 326 132-142 In a systematic study, the National Institute for Occupational Safety and Health (NIOSH) evaluated seat designs in low- and mid-seam shuttle cars during production operations at two underground coal mines in southern West Virginia. The purpose was to support, with additional data, earlier findings that NIOSH ergonomic seat designs (featuring viscoelastic foam padding and lower-back support) may help reduce health risks to operators of coal mine shuttle cars. Eight shuttle car operators evaluated seven seat designs (one already in use in each vehicle and five NIOSH designs) relative to perceived and measured whole-body vibration (WBV) exposure (including vehicle jarring/jolting) and discomfort. Operators' perceptions using a visual analog scale (VAS) and questionnaire ratings were compared with International Standards Organization (ISO) 2631-1:1985 fatigue-decreased proficiency (FDP) limits and measured WBV levels on low- and mid-seam shuttle cars. Objective and subjective data results indicated that NIOSH seat designs (with added adjustability, lower-back support and improved seat padding) performed better to reduce vehicle jarring/jolting levels and that shuttle car operators favored them over existing seat designs. The NIOSH low- and mid-seam shuttle car seats showed 45 to 77 percent better performance in FDP and 9 to 60 percent better performance overall in operators' ratings. Considering the VAS results for low- and mid-seam shuttle cars under no-load conditions, operators rated the level of jarring/jolting 18 to 89 percent lower with the NIOSH seats. Reductions in measured vehicle jarring/jolting were 19 to 46 percent for the three-directional vector sum accelerations relative to the existing seats on the low- and mid-seam shuttle cars. Questionnaire responses indicated that operators for both shuttle car models rated NIOSH seat designs as more comfortable overall. Vehicle operators most frequently suggested adding armrests to improve the seats on the mid-seam shuttle car. A suggested improvement for the low-seam shuttle car was to make the seat a better fit for the operator compartment, which would enhance clearance between the operator and vehicle controls and allow for better seat adjustment and operator visibility. |
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