§ 1036.805 Symbols, abbreviations, and acronyms.
The procedures in this part generally follow either the International System of Units (SI) or the United States customary units, as detailed in NIST Special Publication 811 (incorporated by reference in § 1036.810). See 40 CFR 1065.20 for specific provisions related to these conventions. This section summarizes the way we use symbols, units of measure, and other abbreviations.
(a) Symbols for chemical species. This part uses the following symbols for chemical species and exhaust constituents:
Table 1 to Paragraph (a) of § 1036.805—Symbols for Chemical Species and Exhaust Constituents
| Symbol | Species |
|---|---|
| C | carbon. |
| CH4 | methane. |
| CH4N2O | urea. |
| CO | carbon monoxide. |
| CO2 | carbon dioxide. |
| H2O | water. |
| HC | hydrocarbon. |
| NMHC | nonmethane hydrocarbon. |
| NMHCE | nonmethane hydrocarbon equivalent. |
| NMNEHC | nonmethane nonethane hydrocarbon. |
| NO | nitric oxide. |
| NO2 | nitrogen dioxide. |
| NOX | oxides of nitrogen. |
| N2O | nitrous oxide. |
| PM | particulate matter. |
(b) Symbols for quantities. This part uses the following symbols and units of measure for various quantities:
Table 2 to Paragraph (b) of § 1036.805—Symbols for Quantities
| Symbol | Quantity | Unit | Unit symbol | Unit in terms of SI base units |
|---|---|---|---|---|
| α | atomic hydrogen-to-carbon ratio | mole per mole | mol/mol | 1 |
| Α | Area | square meter | m 2 | m 2 |
| β | atomic oxygen-to-carbon ratio | mole per mole | mol/mol | 1 |
| CdΑ | drag area | meter squared | m 2 | m 2 |
| Crr | coefficient of rolling resistance | newton per kilonewton | N/kN | 10−3 |
| D | distance | miles or meters | mi or m | m |
| e | efficiency | |||
| ∈ | Difference or error quantity | |||
| E | mass weighted emission result | grams/ton-mile | g/ton-mi | g/kg-km |
| Eff | efficiency | |||
| Em | mass-specific net energy content | megajoules/kilogram | MJ/kg | m 2·s−2 |
| fn | angular speed (shaft) | revolutions per minute | r/min | π·30·s−1 |
| g | gravitational acceleration | meters per second squared | m/s 2 | m·s−2 |
| i | indexing variable | |||
| ka | drive axle ratio | 1 | ||
| ktopgear | highest available transmission gear | |||
| m | Mass | pound mass or kilogram | lbm or kg | kg |
| M | molar mass | gram per mole | g/mol | 10−3·kg·mol−1 |
| M | total number in a series | |||
| M | vehicle mass | kilogram | kg | kg |
| Mrotating | inertial mass of rotating components | kilogram | kg | kg |
| N | total number in a series | |||
| Q | total number in a series | |||
| P | Power | kilowatt | kW | 10 3·m 2·kg·s−3 |
| ρ | mass density | kilogram per cubic meter | kg/m 3 | m−3·kg |
| r | tire radius | meter | m | m |
| SEE | standard error of the estimate | |||
| σ | standard deviation | |||
| T | torque (moment of force) | newton meter | N·m | m 2·kg·s−2 |
| t | Time | second | s | s |
| Δt | time interval, period, 1/frequency | second | s | s |
| UF | utility factor | |||
| v | Speed | miles per hour or meters per second | mi/hr or m/s | m·s−1 |
| W | Work | kilowatt-hour | kW·hr | 3.6·m 2·kg·s−1 |
| wC | carbon mass fraction | gram/gram | g/g | 1 |
| wCH4N2O | urea mass fraction | gram/gram | g/g | 1 |
| x | amount of substance mole fraction | mole per mole | mol/mol | 1 |
| xb | brake energy fraction | |||
| xbl | brake energy limit |