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31.
This article presents a formal optimization study of the design of small livestock trailers, within which the majority of animals are transported to market in the UK. The benefits of employing a headboard fairing to reduce aerodynamic drag without compromising the ventilation of the animals’ microclimate are investigated using a multi-stage process involving computational fluid dynamics (CFD), optimal Latin hypercube (OLH) design of experiments (DoE) and moving least squares (MLS) metamodels. Fairings are parameterized in terms of three design variables and CFD solutions are obtained at 50 permutations of design variables. Both global and local search methods are employed to locate the global minimum from metamodels of the objective functions and a Pareto front is generated. The importance of carefully selecting an objective function is demonstrated and optimal fairing designs, offering drag reductions in excess of 5% without compromising animal ventilation, are presented. 相似文献
32.
The electron capture parameters and photoionization cross section of the unintentional deep levels, which are responsible
for photoelectrical memory in GaAs/AlGaAs multilayer quantum-well structures, have been found from an analysis of the kinetics
of the excess current during and after optical illumination of these structures. The dependence of the photoionization cross
section on the photon energy, the capture cross section, and the energy barrier for capture of an electron from the bottom
of the conduction band indicate that the unintentional deep levels are DX centers formed by the silicon impurity. These DX centers probably appear during growth of the structures as a result of silicon diffusion from the quantum wells along as-grown
defects.
Fiz. Tekh. Poluprovodn. 32, 1213–1218 (October 1998) 相似文献
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A. A. Toropov V. Kh. Kaibyshev Ya. V. Terent’ev S. V. Ivanov P. S. Kop’ev 《Semiconductors》2011,45(2):208-214
Exciton photoluminescence spectra, photoluminescence excitation spectra, and magnetophotoluminescence spectra of single (GaAs/AlGaAs/ZnMnSe)
and double (GaAs/AlGaAs/ZnSe/ZnCdMnSe) heterovalent quantum wells formed by molecular beam epitaxy are studied. It is shown
that the exciton absorption spectrum of such quantum wells mainly reproduces the resonant exciton spectrum expected for usual
quantum wells with similar parameters, while the radiative exciton recombination have substantial distinctions, in particular
the additional localization mechanism determined by defects generated by heterovalent interface exists. The nature of these
localization centers is not currently clarified; their presence leads to broadening of photoluminescence lines and to an increase
in the Stokes shift between the peaks of luminescence and absorption, as well as determining the variation in the magnetic
g factor of bound exciton complexes. 相似文献
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