Abstract: A method includes providing a plurality of simulation components (101-105), each simulating operation of a distinct element of a cyber-physical system and including at least first and second simulation components (101, 102) arranged in series with one or more outputs of the first simulation component (101) being provided as input to the second simulation component (102). A plurality of output predictions are generated using a surrogate model of the first simulation component and, in response, a plurality of the second simulation components (102-1, 102-2, 102-3), or a plurality of second surrogate models, are executed in parallel. The input values of each second simulation component (102-1, 102-2, 102-3), or surrogate model corresponds to a respective one of the plurality of output predictions from the surrogate model of the first simulation component (101).