fredlund4: R optmisation of Fredlund et al (2000) four-parameter...

In gowusu/vadose: The estimation of saturated hydraulic conductivity and soil water retention Curves in the vadose zone

Description

The function optimises 4 parameters of Fredlund et al (2000) particle size distribution function

Usage

fredlund4(data = NULL, D = NULL, fr = NULL, p = NULL, group = NULL,
  a = 1, m = 1, n = 1, df = 1)

## Default S3 method:
fredlund4(data = NULL, D = NULL, fr = NULL, p = NULL,
  group = NULL, a = 1, m = 1, n = 1, df = 1)

## S3 method for class 'fredlund4'
plot(x, main = "Particle Size Distribution Function",
  xlab = "Particle Diameter", ylab = "Fraction", ...)

## S3 method for class 'fredlund4'
coef(object, ...)

## S3 method for class 'fredlund4'
predict(object, D, ...)

Arguments

data	dataframe. It can contain data with column names of "time" and "I"
D	character. The corresponding diameter in the data.
fr	character. The corresponding fraction of the particles.
p	porosity[g/m^3]
group	character. The name of the group variables if the data is from different areas.
a	an initial value of 'a' parameter to be optimised
m	character. The water retention curve condition. It takes either "b" for Burdine condition or "m" for Mualem condition.
n	numeric. A shaping parameter for water retention curve. This can be calibrated. If the parameter "PSD" is not set NULL lass3 will be automatically used to estimate it.
df	an initial value of 'df' parameter to be optimised
x	a return object of the function.
main	Title of the plot
xlab	x label of the plot
ylab	y label of the plot
...	Any other graphical parameter
object	Model output object

Value

• PD: predicted fraction by mass of particles passing a particular diameter

• sand: percentage of sand

• clay: percentage of clay

• silt: percentage of silt

• a: optimised a parameter

• m: optimised m parameter

• n: optimised n parameter

• df: optimised df parameter

Author(s)

George Owusu

References

Fredlund, M. D., Fredlund, D. G., & Wilson, G. W. (2000). An equation to represent grain-size distribution. Can Geotech J, 65, 638-648.

See Also

zhuang3, zhuang4,lass3,logarithmic, logistic2, logistic3,logistic4,fredlund3, jaky,andersson,gompertz, haverkamp

Other Fredlund functions: fredlund3

Examples

data=read.csv(system.file("ext","sys","soil2.csv",package="vadose"))
single<- subset(data, ID=="30B20_1")
mod=fredlund4 (data=single,p="sand",D="D",fr="Sand.")
plot(mod)

#group simulation
mod2=fredlund4 (data=data,D="D",fr="FractionSand",group="ID")
mod2$coef
#generic function

gowusu/vadose documentation built on May 17, 2019, 7:59 a.m.