40 C.F.R. § 1036.805

Current through September 30, 2024
Section 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, see § 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
Ccarbon.
CH4methane.
CH4 N2 Ourea.
COcarbon monoxide.
CO2carbon dioxide.
H2 Owater.
HChydrocarbon.
NMHCnonmethane hydrocarbon.
NMHCEnonmethane hydrocarbon equivalent.
NMNEHCnonmethane nonethane hydrocarbon.
NOnitric oxide.
NO2nitrogen dioxide.
NOXoxides of nitrogen.
N2 Onitrous oxide.
PMparticulate 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 symbolUnit in terms of SI base units
[ALPHA]atomic hydrogen-to-carbon ratiomole per molemol/mol1
'Areasquare meterm2m2
[BETA]atomic oxygen-to-carbon ratiomole per molemol/mol1
Cd'drag areameter squaredm2m2
Crrcoefficient of rolling resistancenewton per kilonewtonN/kN10-3
Ddistancemiles or metersmi or mm
eefficiency
[EURO]Difference or error quantity
Emass weighted emission resultgrams/ton-mileg/ton-mig/kg-km
Effefficiency
Emmass-specific net energy contentmegajoules/kilogramMJ/kgm2·s-2
fnangular speed (shaft)revolutions per minuter/min[PI]·30·s-1
ggravitational accelerationmeters per second squaredm/s2m·s-2
iindexing variable
kadrive axle ratio1
ktopgearhighest available transmission gear
mMasspound mass or kilogramlbm or kgkg
Mmolar massgram per moleg/mol 10-3·kg·mol-1
Mtotal number in a series
Mvehicle masskilogramkgkg
Mrotatinginertial mass of rotating componentskilogramkgkg
Ntotal number in a series
Qtotal number in a series
PPowerkilowattkW 103·m2·kg·s- 3
[RHO]mass densitykilogram per cubic meterkg/m3m-3·kg
rtire radiusmetermm
SEEstandard error of the estimate
Astandard deviation
Ttorque (moment of force)newton meterN·m m2·kg·s-2
tTimesecondss
[DELTA]ttime interval, period, 1/frequencysecondss
UFutility factor
vSpeedmiles per hour or meters per secondmi/hr or m/sm·s-1
WWorkkilowatt-hourkW·hr 3.6·m2·kg·s-1
wCcarbon mass fractiongram/gramg/g1
wCH4N2Ourea mass fractiongram/gramg/g1
xamount of substance mole fractionmole per molemol/mol1
xbbrake energy fraction
xblbrake energy limit

(c)Superscripts. This part uses the following superscripts for modifying quantity symbols:

Table 3 to Paragraph (c) of § 1036.805 -Superscripts

Superscript Meaning
overbar (such as y)arithmetic mean.
overdot (such as y)quantity per unit time.

(d)Subscripts. This part uses the following subscripts for modifying quantity symbols:

Table 4 to Paragraph (d) of § 1036.805 -Subscripts

Subscript Meaning
6565 miles per hour.
AA speed.
aabsolute (e.g., absolute difference or error).
accaccessory.
appapproved.
axleaxle.
BB speed.
CC speed.
Ccarbon mass.
Ccombdrycarbon from fuel per mole of dry exhaust.
CDcharge-depleting.
CO2 DEFCO2 resulting from diesel exhaust fluid decomposition.
combcombustion.
compcomposite.
corcorrected.
CScharge-sustaining.
cyclecycle.
Ddistance.
DD speed.
DEFdiesel exhaust fluid.
engineengine.
exhraw exhaust.
frontfrontal.
fuelfuel.
H2 OexhaustdryH2 O in exhaust per mole of exhaust.
hihigh.
ian individual of a series.
idleidle.
inttest interval.
jan individual of a series.
kan individual of a series.
mmass.
maxmaximum.
mappedmapped.
measmeasured quantity.
MYmodel year.
negnegative.
pospositive.
Rrange.
rrelative (e.g., relative difference or error).
raterate (divided by time).
ratedrated.
recordrecord.
refreference quantity.
speedspeed.
stallstall.
testtest.
tiretire.
transienttransient.
[MICRO]vector.
UFutility factor.
vehiclevehicle.

(e)Other acronyms and abbreviations. This part uses the following additional abbreviations and acronyms:

Table 5 to Paragraph (e) of § 1036.805 -Other Acronyms and Abbreviations

Acronym Meaning
ABTaveraging, banking, and trading.
AECDauxiliary emission control device.
ASTMAmerican Society for Testing and Materials.
BTUBritish thermal units.
CDcharge-depleting.
CFRCode of Federal Regulations.
CIcompression-ignition.
COVcoefficient of variation.
CScharge-sustaining.
DEFdiesel exhaust fluid.
DFdeterioration factor.
DOTDepartment of Transportation.
DPFdiesel particulate filter.
E85gasoline blend including nominally 85 percent denatured ethanol.
ECMElectronic Control Module.
EGRexhaust gas recirculation.
EPAEnvironmental Protection Agency.
FCLFamily Certification Level.
FELfamily emission limit.
FTPFederal Test Procedure.
GCWRgross combined weight rating.
GEMGreenhouse gas Emissions Model.
g/hp·hrgrams per brake horsepower-hour.
GPSglobal positioning system.
GVWRgross vehicle weight rating.
Heavy HDEheavy heavy-duty engine (see § 1036.140 ).
Heavy HDVheavy heavy-duty vehicle (see 40 CFR 1037.140 ).
Light HDElight heavy-duty engine (see § 1036.140 ).
Light HDVlight heavy-duty vehicle (see 40 CFR 1037.140 ).
LLCLow Load Cycle.
LPGliquefied petroleum gas.
Medium HDEmedium heavy-duty engine (see § 1036.140 ).
Medium HDVmedium heavy-duty vehicle (see 40 CFR 1037.140 ).
NARANational Archives and Records Administration.
NHTSANational Highway Traffic Safety Administration.
NTEnot-to-exceed.
PEMSportable emission measurement system.
RESSrechargeable energy storage system.
SCRselective catalytic reduction.
SEEstandard error of the estimate.
SETSupplemental Emission Test.
Spark-ignition HDEspark-ignition heavy-duty engine (see § 1036.140 ).
SIspark-ignition.
ULuseful life.
U.SUnited States.
U.S.CUnited States Code.

(f)Constants. This part uses the following constants:

Table 6 to Paragraph (f) of § 1036.805 -Constants

Symbol Quantity Value
ggravitational constant9.80665 m·s-2.
Rmolar gas constant8.314472 J/(mol·K) (m2·kg·s-2·mol -1·K-1).

(g)Prefixes. This part uses the following prefixes to define a quantity:

Table 7 to Paragraph (g) of § 1036.805 -Prefixes

Symbol Quantity Value
[MICRO]micro10-6
mmilli10-3
ccenti10-2
kkilo103
Mmega106

40 C.F.R. §1036.805

88 FR 4487, Jan. 24, 2023, as amended at 89 FR 29765, Apr. 22, 2024
81 FR 74004, 12/27/2016; 86 FR 34404, 7/29/2021; 88 FR 4487, 3/27/2023; As amended at 89 FR 29765, 6/21/2024