MODELING OF THERMAL SYSTEM UNDER PI CONTROLLER WITH PWM OUTPUT

The present work focuses on the modeling of the thermal system composed of several modules, in which the general model of the system is built, which includes all its components in operation. The environment collected data in real time of the growth and decrease (temperature) curve of a soldering iron tool, under aspects of PWM variation - Pulse Width Modulation - of the signal. It is used as a representative model of device in industrial welding, in which it has similarities in key aspects of behavior. Through analysis and software assistance, the function of transferring the general plan was obtained, which showed an acceptable level of correspondence (86.04%) in non-linear systems. Based on the model discovered, a PItype controller - Proportional Integral - was designed, paying attention to the need for a low-level overshoot signal (6.08%) in order to obtain a response to the rapid stabilization step, rare in thermal systems. The PI was developed in order to generate an output in DC format (Duty Cycle format), since the raw data of the system were collected by varying this indicator at regular intervals of time. After the tests carried out in simulation, results were obtained that confirm that the developed control system is applicable and responds appropriately, being able to be optimized for applications.,

Avaliação da qualidade de mudas de mulungu (Erythrina velutina Willd.) submetidas a diferentes métodos de quebra de dormência

<p class="western" align="justify">Several forest species typical of semi-arid regions are used for afforestation and mulungu among them has great ecological importance. This study aims to evaluate the development of mulungu (Erythrina velutina Willd) seedlings from seeds which have been submitted to different dormancy breaking treatments. The seeds were submitted to eleven treatments: mechanical scarification with sandpaper No. 80 (T1); mechanical scarification with sandpaper No. 60 (T2); hole with soldering iron hole(T3); mechanical scarification with sandpaper No. 60 + immersion in water for 24 hours (T4); mechanical scarification with sandpaper No. 80 + immersion in water for 24 hours (T5); immersion in water at 60 °C for 5 minutes (T6); immersion in water at 80 °C for 5 minutes (T7); immersion in water at 90 °C for 5 minutes (T8); immersion in water for 24 hours (T9); immersion in water for 48 hours (T10) and hole with soldering iron hole+ immersion in water for 24 hours (T11). The treatments applied were efficient in the beginning of development the seedling’s (height, stem diameter and number of leaves), the treatments with water immersion showed better results for the analysis of the total fresh phytomass, divergent results from the literature were found for water scarification treatments, resulting in the least developed seedlings. Thus, it seems clear that of E. velutina dormancy can be overcome with different methods, in order to promote faster germination, and the mechanical scarification more efficient in the initial development of the seedling.</p>