Nonlinear heating system of modular-trigger and platform furnaces for firing bulk materials

The design of the suspended nonlinear heating system of modular-trigger and platform furnaces for firing vermiculite and other bulk materials is considered. Previously, the design of linear heating systems did not provide homogeneous heating of thermographed materials, the material in the clutch zones suffered sufficient thermal energy. In addition, overheating of the central zone increased the frequency of the impact of the heaters themselves, which affected the reliability of the furnace. The use of a nonlinear heating system has changed this distribution to the opposite. The power of the intuboxic heater exceeded the power of the central 1,2‒1,36 times depending on the ratio of the diameters of thin and thick (diameter of 4 mm) of the heaters. At the same time, not only their electrical power increased, but the heat radiation streams, falling onto the surface of the supply, which led to an increase in the temperature of the material being processed. The obtained values of the temperature of the vermiculite grains in the fitted zones of the firing module exceed the temperature of the vermiculite in the central zone by 26 %, while it is sufficient for high-quality material intimidation. Due to the use of nonlinear heating system, temperatures were redistributed on heated surfaces in favor of relatively cold previously intuition zones: the heat picture has changed to the opposite, that is, the cold cloth zones have become relatively hot. Ill. 8. Ref. 14.

Modeling and optimizing a road de-icing device by a nonlinear heating

In order to design a road de-icing device by heating, we consider in the one dimensional setting the optimal control of a parabolic equation with a nonlinear boundary condition of the Stefan–Boltzmann type. Both the punctual control and the corresponding state are subjected to a unilateral constraint. This control problem models the heating of a road during a winter period to keep the road surface temperature above a given threshold. The one-dimensional modeling used in this work is a first step of the modeling of a road heating device through the circulation of a coolant in a porous layer of the road. We first prove, under realistic physical assumptions, the well-posedness of the direct problem and the optimal control problem. We then perform some numerical experiments using real data obtained from experimental measurements. This model and the corresponding numerical results allow to quantify the minimal energy to be provided to keep the road surface without frost or snow.

Factors Determining the Asymmetry of ENSO

A fundamental aspect of the observed ENSO is the positive asymmetry between its two phases: the strongest El Niño is stronger than the strongest La Niña. The nonlinear term in the equation for the surface ocean heat budget has been theorized as a cause of the asymmetry. This theory is challenged by the diversity of asymmetry among the CMIP5 models: these models all employ primitive equations and thus have the nonlinear term in the heat budget equation for the ocean surface, yet the asymmetry simulated by these models ranges from significantly negative to significantly positive. Here, the authors employ an analytical but nonlinear model—a model that simulates the observed ENSO asymmetry—to show that the nonlinear heating term does not guarantee the oscillation in the system to possess positive asymmetry. Rather, the system can have regimes with negative, zero, and positive asymmetry. The regime in which the system finds itself depends on a multitude of physical parameters. Moreover, the range of certain physical parameters for the system to fall in the regime with positive asymmetry in the oscillation is rather narrow, underscoring the difficulty of simulating the observed ENSO asymmetry by CMIP5 models. Moreover, stronger positive asymmetry is found to be associated with a more complicated oscillation pattern: the two adjacent strongest warm events are spaced farther apart and more small events occur in between. These results deepen the understanding of factors that are behind the asymmetry of ENSO and offer paths to take to improve model-simulated ENSO asymmetry.

Topographic Effects on the Tropical Land and Sea Breeze

The effect of an inland plateau on the tropical sea breeze is considered in terms of idealized numerical experiments, with a particular emphasis on offshore effects. The sea breeze is modeled as the response to an oscillating interior heat source over land. The parameter space for the calculations is defined by a nondimensional wind speed, a scaled plateau height, and the nondimensional heating amplitude. The experiments show that the inland plateau tends to significantly strengthen the land-breeze part of the circulation, as compared to the case without terrain. The strengthening of the land breeze is tied to blocking of the sea-breeze density current during the warm phase of the cycle. The blocked sea breeze produces a pool of relatively cold, stagnant air at the base of the plateau, which in turn produces a stronger land-breeze density current the following morning. Experiments show that the strength of the land breeze increases with the terrain height, at least for moderate values of the height. For very large terrain, the sea breeze is apparently blocked entirely, and further increases in terrain height lead to only small changes in land-breeze intensity and propagation. Details of the dynamics are described in terms of the transition from linear to nonlinear heating amplitudes, as well as for cases with and without background winds. The results show that for the present experiments, significant offshore effects are tied to nonlinear frontal propagation, as opposed to quasi-linear wave features.