3.1.2.vsp.calculations {pems.utils} | R Documentation |
Functions associated with VSP calculations.
calcVSP(speed = NULL, accel = NULL, slope = NULL, time = NULL, distance = NULL, data = NULL, calc.method = calcVSP_JimenezPalacios, ..., fun.name = "calcVSP", this.call = NULL) calcVSP_JimenezPalacios(speed = NULL, accel = NULL, slope = NULL, vehicle.weight = NULL, vsp.a = NULL, vsp.b = NULL, vsp.c = NULL, vsp.g = NULL, ..., data = NULL, fun.name = "calcVSP_JimenezPalacios", this.call = NULL) binVSP(..., bin.method="ncsu.14") #associated methods binVSP_NCSU.14(vsp = NULL, data = NULL, ..., fun.name="binVSP_NSCU.14") binVSP_MOVES.23(vsp = NULL, speed = NULL, data = NULL, ..., fun.name="binVSP_MOVES.23")
speed, accel, slope, time, distance, vsp |
(Typically pems.element vectors) |
data |
(Optional, typically |
calc.method, bin.method |
(Required functions) |
... |
(Optional) Other arguments, currently passed on as supplied to e.g.
|
fun.name |
(Optional character) The name of the parent function, to be used in error messaging. |
this.call |
(Optional) Initial call, should generally be ignored. See codecommon.calculations for further details. |
vehicle.weight, vsp.a, vsp.b, vsp.c, vsp.g |
(Numerics) VSP constants. If not supplied, defaults are applied. See Below. |
calcVSP...
functions calculate VSP:
calcVSP
is a wrapper function which allows users to supply
different combinations of inputs. VSP calculations typically require
speed, acceleration and slope inputs. This wrapper allows different
input combinations, e.g.:
time and distance (time and distance -> speed, time and speed -> accel)
time and speed (time and speed -> accel)
speed and accel
This then passes on speed
, accel
and (if supplied)
slope
to the method defined by calc.method
. (This means
other VSP functions run via calcVSP(..., calc.method = function)
share this option without needed dedicated code.)
calcVSP_JimenezPalacios
calculates VSP according to Jimenez Palacios
methods. See References and Note below.
binVSP
generates VSP Mode bins depending on method applied.
binVSP_NCSU.14
bins supplied vsp
using the 14 bin method
described in Frey et al 2002.
binVSP_MOVES.23
bins supplied vsp
using that and speed
and the 23 bin MOVES method (See Note).
calcVSP_JimenezPalacios
and calcVSP
by default use
Jimenez Palacios method to calculate VSP in kW/metric ton.
binVSP
generates a pems.element factor
vector of VSP Mode
Bin assignments.
calcVSP...
constants can be set/modified in the calculation call, e.g.
calcVSP(..., vsp.a = [new.value])
. If not supplied, defaults are used
(see References).
binVSP_MOVES.23
is in-development. Do not use without independent
confirmation of values.
Unit handling in pems.utils
is via checkUnits
,
getUnits
, setUnits
and
convertUnits
. See common.calculations
for details.
Karl Ropkins
calcVSP_JimenezPalacios
uses methods described in:
Jimenez-Palacios, J.L. (1999) Understanding and Quantifying Motor Vehicle Emissions with Vehicle Specific Power and TILDAS Remote Sensing. PhD Thesis, Massachusetts Institute of Technology, Cambridge, MA.
vehicle.weight
is the vehicle mass (in metric tons), and vsp.a
,
vsp.b
, vsp.c
and vsp.g
are the calculations constants for:
vsp = speed * (a * accel + (g * slope) + b) + (c * speed^3)
By default: a = 1.1, b = 0.132, c = 0.000302 and g = 0.132 (as of Jimenez-Palacios, 1999).
Method ONLY INTENDED FOR vehicles < 3.855 metric tons.
binVSP_NCSU.14
VSP binning as described in:
Frey, H.C., Unal, A., Chen, J., Li, S. and Xuan, C., 2002. Methodology for developing modal emission rates for EPA's multi-scale motor vehicle & equipment emission system. Ann Arbor, Michigan: US Environmental Protection Agency. (EPA420-R-02-027)
See common.calculations
(and checkUnits
and
convertUnits
) for details of data management.
########### ##example 1 ########### #basic usage vsp <- calcVSP(velocity, time = local.time, data = pems.1) #where the returned object, vsp, is vsp values as pems.element ncsu.14 <- binVSP(vsp) #where the returned object, nscu.14, is the associated modal bin # assignments based on the Frey et al (2002) 14 bin method.