Читать книгу Control Theory Applications for Dynamic Production Systems - Neil A. Duffie - Страница 22

Variables in discrete-time models have a value only at discrete instants in time separated by a fixed time interval T. While many physical variables in production systems are fundamentally continuous, they often are sampled, calculated, or changed periodically. Examples include work in progress (WIP) measured manually or automatically at the beginning of each day, mean lead time calculated at the end of each month, and production capacity adjusted at the beginning of each week. Discrete-time modeling results in difference and algebraic equations that describe input–output relationships and represent the behavior of a production system at times kT where k is an integer.