Hierarchical control distributed layer

Practical considerations in implementing the hierarchical control framework developed above concern the availability of manipulated inputs to address the control objectives in the slow time scale (it is possible that dim(us) < dim(ys)), as well as achieving a tighter coordination between the distributed and supervisory control layers. Both issues are effectively addressed by using a cascaded control configuration, which extends the choice of controlled variables in the slow time scale to include the setpoints y)p of the distributed controllers. 

Figure 3.4 Hierarchical control relies on separate, but coordinated, fast and slow controllers, designed on the basis of the respective reduced-order models, to compute the values of the separate inputs that influence the fast and slow dynamics of the process. Tighter coordination between the distributed and supervisory control layers is achieved by using a cascaded configuration.

On nanostructured diamond layers, the number of initially adhered cells on day 1 after seeding was similar to that foimd on the control TCPS (Fig. IID), whereas on the layers with a combined micro and nanoarchitecture, this number was significantly lower. In addition, the cells on the latter samples were distributed non-homogeneously [23]. However, from day 1 to 3 after seeding, the cells on the hierarchically micro- and nanostructured layers, which are considered to resemble the architecture of natural tissues, showed the quickest proliferation. Their doubling time was 23.4 h, whereas on the nanostructured layers, it was 56.7 h, and on TCPS, the cells still remained in the lag phase and have not yet started their proliferation [23]. As a result, on day 3 after seeding, the cells on the diamond layers with a combined micro-and nanostructure reached the highest cell population density compared to nanostructured diamond and TCPS, respectively [23]. 

---