3.1.11.4. Ramp TimeSeries

This command is used to construct a TimeSeries object in which the load factor is a linear Ramp function. An optional -smooth flag provides an adjustable smoothness, allowing for a smooth transition at the start and end of the ramp. The default behavior provides a linear ramp from 0 to 1.0. By providing a smoothness > 0, the time series has a continuous derivative. The smoothing interval is equal to the smoothness factor times half the ramp time.

The load factor is determined as:

\[\begin{split}\lambda = f(t) = offset + cFactor * \begin{cases} 0.0 & t < T_{Start}\\ \left( \frac{\left(t -T_{Start} \right )}{T_{Ramp}}\right)^2\left( \frac{2}{S(2-S))}\right) &t <= T_{Start}+S\left(\frac{T_{Ramp}}{2}\right)\\ \frac{1}{2}+\left(\frac{t-T_{Start}-\frac{T_{Ramp}}{2}}{T_{Ramp}} \right)\left (\frac{2}{2-S} \right ) &t <= T_{Start}+T_{Ramp}-S\left(\frac{T_{Ramp}}{2}\right )\\ 1-\left(\frac{t-T_{Start}-T_{Ramp}}{T_{Ramp}} \right)^2\left (\frac{2}{S(2-S)} \right ) &t<= T_{Start}+T_{Ramp} \\ 1.0 & \text{otherwise} \end{cases} \\\end{split}\]

With: \(S = smoothness \rightarrow 0<=S<=1.0\)

timeSeries Ramp $tag? $tStart? $tRamp? <-smooth $smoothness?> <-offset $offset?> <-factor $cFactor?>

Argument	Type	Description
$tag	integer	unique tag among TimeSeries objects.
$tStart	float	starting time of non-zero load factor
$tRamp	float	length of time to perform the ramp
‘-smooth’	string	optional flag to enable smooth ramp
$smoothness	float	smoothness parameter (optional: 0 ≤ $smoothness ≤ 1 default = 0.0)
‘-offset’	string	optional flag to provide vertical offset
$offset	float	vertical offset amount (optional: default = 0.0
‘-factor’	string	optional flag to provide scale factor
$cFactor	float	the load factor scale factor (optional: default = 1.0)

Example 1:

The following code demonstrates how a user would create a ramp time series with a tag of 1, has a start time of $tStart = 5.0, a ramp time of $tRamp = 30.0, a $smoothness value of 0.25, an $offset of -1.0, and a scale factor of $cFactor = 2.0.

1. Tcl Code

timeSeries Ramp 1 5.0 30.0 -smooth 0.25 -offset -1.0 -factor 2.0

1. Python Code

timeSeries('Ramp', 1, 5.0, 30.0, '-smooth', 0.25, '-offset', -1.0, '-factor', 2.0)

Example 2:

The following code demonstrates how a user would create a ramp time series with a tag of 2, has a start time of $tStart = 10.0, a ramp time of $tRamp = 30.0, a $smoothness value of 0.1, an $offset of 2.0, and a scale factor of $cFactor = -2.0.

1. Tcl Code

timeSeries Ramp 2 10.0 30.0 -smooth 0.1 -offset 2.0 -factor -2.0

2. Python Code

timeSeries('Ramp', 2, 10.0, 30.0, '-smooth', 0.1, '-offset', 2.0, '-factor', -2.0)

Code Developed by: Codi McKee (Texas A&M University)