a, b

constants in two parameter Weibull distribution

f

frequency

G( f)

power spectral density

H

wave height

H _{1 / 3}

significant wave height

I

irregularity factor

m ₀, m ₂, m ₄

moments of spectral density function

N

number of cycles, return period

P( H _{1 / 3})

exceedance of H _{1 / 3}

P( S)

exceedance of S

P( S/ ?)

exceedance of S/s

p( S)

probability density of S

p( S/ ?)

probability density of S/ ?

R( ?)

autocorrelation function

S

random process

s

instantaneous value of S

S / ?

expected value of S/ ?

S _c / ?

clipping ratio

S _m

mean value of S

S _o

value of S below which peaks are omitted

T

total time, wave period

t

time

?

Euler s constant = 0 .5772

?

spectral bandwidth

?

standard deviation (random process theory), root mean square (fatigue)

? _p

root mean square of peaks

? _{p , c}

root mean square of peaks after clipping of high peaks

? _{p , o}

root mean square of peaks after omission of low peaks

?