# Glossary

Sampling
In the context of the GUI a Sampling is the same as a Case. It is based on a unique subset of variables.
In general, Sampling is synonymous with Point Selection or Experimental Design.
Saturated design
An experimental design in which the number of points equals the number of unknown coefficients of the approximation. For a saturated design no test can be made for the lack of fit.
Scale factor
A factor which is specified as a divisor of a response in order to normalize the response.
Sensitivity
See Design sensitivity.
Sequential Random Search
An iterative method in which the best design is selected from all the simulation results of each iteration. A Monte Carlo based point selection scheme is typically applied to generate a set of design points.
Simulation
The analysis of a physical process or entity in order to compute useful responses. See Function evaluation.
Slack constraint
A constraint with a slack variable. The violation of this constraint can be minimized.
Slack variable
The variable which is minimized to find a feasible solution to an optimization problem, e.g. e in: min e subject to g j ( x) ≤ e; e ≥ 0. See Strictness.
Solver
A computational tool used to analyze a structure or fluid using a mathematical model. See Discipline.
Space Filling Experimental Design
A class of experimental designs that employ an algorithm to maximize the minimum distance between any two points.
Space Mapping
A technique which uses a fine design model to improve a coarse surrogate model. The hope is, that if the misalignment between the coarse and fine models is not too large, only a few fine model simulations will be required to significantly improve the coarse model. The coarse model can be a response surface.
Stage
A distinct step or operation in a process which typically reads input, processes the input and produces a result. Example: run a solver.
Different stages can be dependent on one another.
Stage directory
A subdirectory of the work directory that bears the name of a solver and where database files resulting from extraction and the optimization process are stored.
Stochastic
Involving or containing random variables. Involving probability or chance.
Stopping Criterion
A mathematical criterion for terminating an iterative procedure.
Strictness
A number between 0 and 1 which signifies the strictness with which a design constraint must be treated. A zero value implies that the constraint may be violated. If a feasible design is possible all constraints will be satisfied. Used in the design formulation to minimize constraint violations. See Slack variable.
Subproblem
The approximate design subproblem constructed using response surfaces. It is solved to find an approximate optimum.
Subregion
See region of interest.
Successive (or Sequential) Approximation Method
An iterative method using the successive solution of approximate subproblems.
System identification
A procedure in which a numerical model is calibrated by optimizing selected parameters in order to minimize the residual error with respect to certain targeted responses. The targeted responses are usually derived from experimental results.