Bevel-helical gear unit B3 sions fourstage gear unit sizes to Selection a B3SH-13-C

Flender/Flender Gear Units/Bevel-helical gear unit B3

o the model parameters in such way that the selection of the specied closed-loop response yields physically realizable feedback controller (1,1,2,. IMC is advantageous because it can be adjusted to balance controller perfor- mance with control system robustness when either modeling errors or changes in processdynamics occur. Clearly, the effectiveness of IMC depends on availability of reliable dryer model. The structure of an IMC system is depicted in the scheme represented in Fig. 6. Fig. 5 Scheme of inferential control of the drying process. Control Aspects 8 Fig. 6 Scheme of internal model control of the drying process. 2.3.5 Direct Digital Control Traditionally, analog instrumentation was used, and in some cases is still being used for process control. Following up on the fast development in computer technology, coupled with signicant reduction in cost in the early 1s, sophisticated computer-based control systems and controllers have evolved. Although the primary task of computer-based controller is implementation of control algorithm (PID or more sophisticated algorithms), the presence of computermakes it possible to achieve more than basic control and to assign number of tasksthat are useful in process control. The following computer control system characteristicsillustrate some of these tasks (1,2,: 1. Implementation of classic and advanced control algorithms. 2. single digital computer (or microprocessor) that services number of control loops (time-shared basis). 3. Distributed data processing by which data can be collected from different pro- cess instruments and processed for monitoring and control purposes. The com-puter system can also be connected to local analytical instruments (.., moisture and humidity meters), which usually have their own microcomputer. 4. Static and dynamic displays on monitors or other visual display units.5. Mathematical functions.6. Data acquisition and storage for different process measurements, such as tem- peratu