Simulation and analysis of hot plume infrared signature based on SNB model

Numerical calculation of infrared emission from hot plume is of great significance for flight monitoring and detections. In this paper, the SNB (statistical narrow band) model established with parameters derived from the high-resolution spectral database HITEMP 2010 is used to perform the hot plume infrared signature simulations. Accuracy of the model is examined by the exact LBL (line by line) method, which proves the model’s reliability to predict radiative properties of combustion gases. In the application part, the SNB model is used to analyze infrared signatures of aircraft plumes cruising at different flight altitudes. The results show that cruising at a higher-altitude will obviously reduce the plume infrared emission. Besides, the plume infrared emissive energy mainly concentrates in a special wavenumber interval and can be strongly absorbed by atmosphere.

Сравнительное исследование коэффициента Нернста--Эттингсгаузена в нормальной фазе в системах Y-=SUB=-1-x-=/SUB=-Pr-=SUB=-x-=/SUB=-Ba-=SUB=-2-=/SUB=-Cu-=SUB=-3-=/SUB=-O-=SUB=-y-=/SUB=- и Y-=SUB=-0.85-x-=/SUB=-Pr-=SUB=-x-=/SUB=-Ca-=SUB=-0.15-=/SUB=-Ba-=SUB=-2-=/SUB=-Cu-=SUB=-3-=/SUB=-O-=SUB=-y-=/SUB=-

In this paper, we present the results of a comparative study of the modification of the temperature dependences of the normal-state Nernst coefficient, Q, under praseodymium doping for two sample series of the Y1-xPrxBa2Cu3Oy and Y0.85-xPrxCa0.15Ba2Cu3Oy compositions. Peculiarities of the Q(T) and Q300 K(x) dependences induced by the presence of additional calcium ions in the YBa2Cu3Oy lattice are revealed and analyzed. It is shown that both the Q(T) dependences and the thermopower temperature dependence obtained earlier for the same samples can be fully described on the basis of a narrow-band model. The values of the charge-carrier mobility and the degree of a dispersion law asymmetry are determined by the quantitative analysis of the experimental results. The presence of additional calcium ions in the lattice is shown to not influence a variation of the dispersion law asymmetry with increasing praseodymium doping but to affect strongly the mobility behavior. The observed dependence of the mobility on the doping level in both investigated systems, as well as a difference in variation of the thermopower and Nernst coefficient values in the Y0.85-xPrxCa0.15Ba2Cu3Oy system are explained based on analyzing mechanisms of the influence of the energy spectrum parameters on the mobility value in the YBa2Cu3Oy system.

Efficient Local Level Set Method without Reinitialization and Its Appliance to Topology Optimization

The local level set method (LLSM) is higher than the LSMs with global models in computational efficiency, because of the use of narrow-band model. The computational efficiency of the LLSM can be further increased by avoiding the reinitialization procedure by introducing a distance regularized equation (DRE). The numerical stability of the DRE can be ensured by a proposed conditionally stable difference scheme under reverse diffusion constraints. Nevertheless, the proposed method possesses no mechanism to nucleate new holes in the material domain for two-dimensional structures, so that a bidirectional evolutionary algorithm based on discrete level set functions is combined with the LLSM to replace the numerical process of hole nucleation. Numerical examples are given to show high computational efficiency and numerical stability of this algorithm for topology optimization.