Temperature Control of a Solar Furnace with Exact Linearization and Off-Line Identification
The ability to predict the behavior of materials is crucial in several industries due to safety aspects, such as in high temperature furnaces for the production of glass, in the nuclear energy industry or in the high concentrated thermal solar systems. Solar furnaces use concentrated solar radiation that can be used to perform material stress tests with high temperatures. These devices have nonlinear dynamics that are caused by the actuator, the shutter, and by the interaction between the solar energy and the properties of the material. The contribution of this paper consists in the design of a controller for practical use based on the exact linearization method with off-line identification. The aim is to improve the controller performance to track the temperature profile. In this context it is assumed that the thermodynamic properties of the sample material to be tested are unknown.
Control of a solar furnace using active cooling
This paper explores a control architecture for a solar furnace that uses active cooling to improve the temperature reference tracking during the decreasing phase of the reference. This is done in conjunction with the command of the shutter that adjusts the incident power and compensates sun power variability due to weather conditions. The controller uses exact linerization coupled with a PI controller to handle model parameter uncertainty. Off-line identification is employed to characterize the temperature dynamics, this is used to avoid online adaptation mechanisms that may cause stability problems during the controller startup, that may melt the material sample. Experimental results obtained from the plant in closed loop control using active cooling are presented.
The first ground cricket (Orthoptera: Trigonidiidae: Nemobiinae) from mid-Cretaceous Burmese amber
Abstract A new genus and species, Birmaninemobius hirsutus gen. et sp. nov., is described on the basis of a well-preserved orthopteran specimen in mid-Cretaceous Burmese amber and attributed to the subfamily Nemobiinae (ground crickets) of the family Trigonidiidae (Grylloidea). As the first record of Nemobiinae from mid-Cretaceous Burmese amber, this new taxon not only provides novel morphological diversity in ground crickets but also indicates that the ground crickets lived in Burma (Tethyan islands) as early as the mid-Cretaceous.