Evaluation of the effects of diesel oxidation catalysts on NO<sub>2</sub> emissions from diesel-powered mining vehicles
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Bibliographic record
Abstract
ABSTRACT Diesel-powered vehicles, particularly those equipped with oxidation catalysts (diesel oxidation catalysts, DOCs) are one of the major contributors to concentrations of toxic NO2 in underground mines. Potentially, the adverse effects of catalysts on NO2 emissions could result in higher exposures to NO2. In this study, 16 in-service DOCs supplied by various mining operations and five new DOCs with advanced catalyst formation supplied by manufacturers were tested. The testing took place at the CanmetMINING Diesel Research Laboratory in Ottawa; and was executed following two types of protocols: progressive load test (PLT) and vehicle transient test (VTT). The VTT consisted of four cycles that simulated operation of a load-haul-dump (LHD) vehicle, pickup truck, utility vehicle, and tractor. The DOCs were tested in a controlled laboratory environment using a single engine coupled to a dynamometer. The laboratory gas analyzers were used to characterize gaseous emissions including carbon monoxide (CO), carbon dioxide (CO2), nitric oxide (NO), oxides of nitrogen (NO x ), and total hydrocarbons (THCs). DOCs with three different types of catalyst formulations were evaluated during this study: (1) platinum group (group 1); (2) base metal/palladium (group 2) group; and (3) “advanced” group (group 3). All DOCs were found to reduce carbon monoxide (CO) and total hydrocarbon emissions. However, the change in NO2 (g/kWh) emissions over the VTT ranged from an increase of 446% to a reduction of 47%. In general, the increase in NO2 emission was much higher than the reduction for the in-use groups 1 and 2 DOCs; where the advanced group 3 DOCs saw an average reduction of NO2 (g/kWh) emissions by 73% (range from 47% to 94%). Therefore, advanced formulation DOCs designed for NO2 suppression are recommended for use in underground mines. The PLT provided emission conversion efficiencies for tested DOCs over the wide engine operating temperature range which can be used to estimate the effects of DOC emissions of a particular vehicle when operated over actual mine duty cycles. This paper discusses the study approach and test results of changes in NO2-specific emissions from DOCs.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it