Chapter 5 Robust Performance Tailoring with Tuning - SSL - MIT

initial design variable state, x = x0, an initial temperature, T = T0 and a set of
optimization parameters. The initial cost is calculated from x0 and stored. In the
SCI development model, this step is equivalent to determining the RMS OPD for
the initial design. The counters, A and R, are used to track the number of designs
accepted and rejected at each temperature and are initially set to zero.
To begin the search, new values for the design variables, xk, in the neighborhood
of the current design, xk−1 are generated:
x i k = xi k−1 + dxi k
(2.42)
where the superscript indicates the ith element of x. A study in [61] shows that to
conduct an efficient search of the solution space it is desirable to change only two or
three design variables at a time. The optimization parameter, ndof, indicates how
many degrees of freedom to change per iteration. If ndof = 2, two design variables,
chosen randomly from the vector �x, are changed and the others remain static. The
magnitude of the change, dxi k , is chosen from a random uniform distribution bounded
by ∆x:
−∆x i