## 4 Temperature Profile Control
An example of such an approach was developed, in which two groups of three inductors are used with a dedicated positioning algorithm (Figure 17a). Figure 17: Scheme of the organization of inductors in a 2 \(\times\) 3 arrangement (**a**) and a network of actions by the algorithm for determining the positions of the inductors along the cylinder generatrix, based on the temperature profile (**b**). The flowchart of the algorithm is shown in Figure 17b. After simple modification, it can be used for systems counting any number of inductors divided into any number of groups. The algorithm in Figure 17 controls the locations of the inductors, which are arranged in two groups of three inductors. The inductors are moved to places characterized by the highest temperature error, taking into account limitations including the width of the inductor (the distance between inductors in the same group must be greater than their width) and the width of the overlapping interactions of inductors in different groups. To compare the proposed algorithm to the systematic approach applied for a given set of inductors a heating experiment to the required temperature of 70 \({}^{\circ}\)C was conducted. The experiment illustrated the control quality in different heating phases. The process requirements were to heat up the cylinder surface uniformly from the ambient temperature and stabilize it at the required level, maintaining uniform temperature distribution along the cylinder generatrix. During the experiment, the irregularity indicators of the temperature profiles along the cylinder generatrix were determined based on the maximum and minimum values of the profile: \(\Delta\)T(t) = T\({}_{\text{max}}\)(t) - T\({}_{\text{min}}\)(t). The results are shown in Figure 18.  
Analyzing the irregularity indicators of the temperature profiles along the cylinder generatrix shown in the lower part of Figure 18, it can be seen that, during the whole experiment, the difference between the maximum and minimum temperatures on the drying cylinder surface did not exceed 3 \({}^{\circ}\)C, whereas with the systematic algorithm it reached 14 \({}^{\circ}\)C. This proves that much higher uniformity of temperature distribution was achieved using the dedicated algorithm. Moreover, the unevenness of the temperature distribution during the experiment remained at a fairly constant level with the dedicated algorithm, whereas with the systematic algorithm it exhibited a clear maximum at t\({}_{1}\). More detailed analysis of the experiment, especially of the temperature distributions along the forming cylinder shown in Figure 19, revealed that because the boundaries of the cylinder naturally have much higher heat losses than the center, even when supplied with the full available power the systematically positioned inductors are unable to deliver enough heating energy. This results in a high irregularity of the temperature profile for the systematic algorithm, especially in the heating-up phase of the process, where it reached 14 \({}^{\circ}\)C at time t\({}_{1}\) (Figure 19a). At t\({}_{1}\), the internal part of the cylinder surface reached the set temperature value, so it ceased to be heated. After t\({}_{1}\), only the points that had not yet  
Figure 18: Temperature waveforms of the cylinder surface during heating (averaged values along the perimeter of the cylinder, T\({}_{\text{avg}}\), and the irregularity indicators of the temperature profiles along the cylinder generatrix; s—systematic algorithm; d—dedicated algorithm). reached the set temperature value were heated. As a result, the temperature difference between the sides of the cylinder and its center began to decrease and reached around 3 \({}^{\circ}\)C at the end of the experiment (Figure 19b). Figure 19 shows that the course of the experiment was qualitatively different when the dedicated positioning algorithm was used.