Vehicle Specific Power (VSP) calculations
Functions associated with VSP calculations.
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calcVSP(speed = NULL, accel = NULL, slope = NULL, time = NULL, distance = NULL, data = NULL, calc.method = calcVSPJimenezPalaciosCMEM, ..., fun.name = "calcVSP", this.call = NULL, hijack= FALSE) calcVSPJimenezPalaciosCMEM(speed = NULL, accel = NULL, slope = NULL, m = NULL, a = NULL, b = NULL, c = NULL, g = NULL, ..., data = NULL, fun.name = "calcVSPJimenezPalaciosCMEM", this.call = NULL, hijack= FALSE)
(Data series, typically vectors) The inputs to use when doing a calculation. See
(Required function) The function to use to calculate VSP. (default
(Optional) Other arguments, currently passed on to function provided as
(Optional character) The name of the parent function, to be used in error messaging.
(Optional) Initial call, should generally be ignored. See codecommon.calculations for further details.
(Logical) Is this function being locally 'hijacked' by a user/function developer? See Note on
(Numerics) VSP constants. If not supplied or preset in the associated
calcVSP... functions calculate VSP using.
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
... and passes on speed and accel to the method defined by
calc.method. (This means
all VSP functions run via
calcVSP(..., calc.method = function) share this option
without needed dedicated code and only required speed and accel as inputs.)
calcVSPJimenezPalaciosCMEM calculates VSP according to Jimenez Palacios and CMEM methods.
See References and Note below.
calcVSP by default use Jimenez Palacios and CMEM
methods to calculate VSP (in kW/metric ton).
calcVSPJimenezPalaciosCMEM does not currently have special case for buses as of
Giannelli et al (2005). (Please let me know if you need to use them.)
calcVSP... constants can be set/modified in the calculation call, e.g.
calcVSP(..., a = [new.value]). If not supplied these are first checked for
in the associated
pems object (if supplied), or set to default values. See
References. If VSP constants are to be added to a
pems object, these should
have the prefix 'vsp.', so for, e.g.,
a is stored in pems constants are
vsp.a. This is because the common VSP designations (
etc.) can be very easily wrongly assigned.
Unit handling in
pems.utils is via
hijack is an in-development argument, supplied to allow code developers to run multiple
functions in different function environments. When developers 'mix and match' code from
several sources it can become unstable, especially if functions are run within functions within
hijack = TRUE and associated code makes a function local to 'side-step'
this issue. This work by assuming/expecting all inputs to be local, i.e. supplied directly by
the code user.
calcVSPJimenezPalaciosCMEM 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.
Giannelli, R.A., Nam, E.K., Helmer, K., Younglove, T., Scora, G., and Barth, M. (2005) Heavy-Duty Diesel Vehicle Fuel Consumption Modelling Based on Road Load and Power Train Parameters. SAE Technical Papers, No, 05CV-3.
m is the vehicle mass (in metric tons), and
are the calculations constants for:
vsp = speed * (a * accel + (g * slope) + b) + (c * speed^3)
In all cases, by default b = 0.132, g = 9.81, and if not supplied
slope is assumed to be
m is assumed to 1.5 metric tons.
For vehicles < 3.855 metric tons; a = 1.1, and c = 0.000302 (as of Jimenez-Palacios, 1999).
For vehicles 3.855 to 6.350 metric tone; a = 0.0996m/2204.6, c = 1.47 + 5.22e-5m/2205 (as of Giannelli et al, 2005).
For vehicles 6.350 to 14.968 metric tone; a = 0.0875m/2204.6, c = 1.93 + 5.90e-5m/2205 (as of Giannelli et al, 2005).
For vehicles > 14.968 metric tone; a = 0.0661m/2204.6, c = 2.89 + 4.21e-5m/2205 (as of Giannelli et al, 2005).
convertUnits) for details of data management.
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