pb210_inventory | R Documentation |
The cumulative content of lead-210 from the bottom of the core is the basis
for the constant rate of supply model, and is a required input to
pb210_crs()
. There are as many ways to calculate this as there are people
who interpret lead-210 activities. This function models the bottom (below
measured lead-210), middle (between measured values of lead-210), and top
(above measured lead-210) with separate models to accomodate the variety of
methods. By default, lead-210 activity is estimated for samples in which it
was not measured by an exponential fit of lead-210 activity vs. cumulative dry mass
(bottom), and repeating the maximum value (top). Inventory for all values is
estimated using a trapezoidal approximation.
pb210_inventory( cumulative_dry_mass, excess, model_top = max_finite(excess), model_bottom = pb210_fit_loglinear(cumulative_dry_mass, excess, subset = ~finite_tail(..1, ..2, n_tail = 3)) ) pb210_inventory_calculator( model_top = ~max_finite(..2), model_bottom = ~pb210_fit_loglinear(..1, ..2, ~finite_tail(..1, ..2, n_tail = 3)) ) ## S3 method for class 'inventory_calculator' predict(object, cumulative_dry_mass, excess, ...)
cumulative_dry_mass |
The cumulative dry mass of the core (in kg), starting at the surface sample and including all samples in the core. These must be greater than 0 and in increasing order. |
excess |
An excess (non-erosional) lead-210 specific activity (in Bq/kg)
for samples where this was measured, and NA where lead-210 was not measured. Use
|
model_top |
A fit object, such as one generated by |
model_bottom |
A fit object that will be used to model activities below
the last positive finite lead-210 activity. Use a constant to specify a custom
deep inventory of lead-210. Can also be a lambda-function of
|
object |
An inventory calculator generated by
|
... |
Unused. |
pb210_inventory()
returns a vector with errors::errors()
of
cumulative lead-210 activities for each sample (in Bq) that can be passed
as the inventory
to pb210_crs()
. pb210_inventory_calculator()
returns
a fit object that can be used to calculate inventory given a
cumulative_dry_mass
and an excess
.
fake_mass <- 1:10 fake_pb210 <- exp(5 - fake_mass) pb210_inventory(fake_mass, fake_pb210) # compare with known inventory from integrating # exp(5 - fake_mass) to +Inf exp(-1 * fake_mass + 5) / -(-1)
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