On quasilinear parabolic evolution equations in weighted Lp-spaces II

Our study of abstract quasi-linear parabolic problems in time-weighted L_p-spaces, begun in [17], is extended in this paper to include singular lower order terms, while keeping low initial regularity. The results are applied to reaction-diffusion problems, including Maxwell-Stefan diffusion, and to geometric evolution equations like the surface-diffusion flow or the Willmore flow. The method presented here will be applicable to other parabolic systems, including free boundary problems.Comment: 21 page

Impact of iron on the room temperature luminescence efficiency of oxygen-containing precipitates in silicon

Oxygen precipitation in silicon has been associated with a weak room temperature sub-bandgap luminescence emission at around 1600 nm. We show that the additional presence of iron impurities enhances this emission by an order of magnitude and results in a red shift of the peak luminescence by approximately 45 nm. We not only observe an increase in the luminescence emission with iron contamination level but also with the density and size of the oxide precipitates. Moreover, we provide evidence that the sub-bandgap luminescence emission increases proportionally with the concentration of iron segregated to oxide precipitates after high temperature (>700 °C) annealing and thus allows evaluation of the gettering efficiency of oxygen-containing precipitates. Annealing of iron-contaminated samples at low temperatures (550 °C) results in a considerable reduction in the interstitial iron concentration without changing the sub-bandgap luminescence, indicating that the sink to which iron diffuses depends upon temperature

On the Maxwell-Stefan approach to multicomponent diffusion

We consider the system of Maxwell-Stefan equations which describe multicomponent diffusive fluxes in non-dilute solutions or gas mixtures. We apply the Perron-Frobenius theorem to the irreducible and quasi-positive matrix which governs the flux-force relations and are able to show normal ellipticity of the associated multicomponent diffusion operator. This provides local-in-time wellposedness of the Maxwell-Stefan multicomponent diffusion system in the isobaric, isothermal case.Comment: Based on a talk given at the Conference on Nonlinear Parabolic Problems in Bedlewo, Mai 200

Рекомендации по ограничению динамических перенапряжений в обмотке ротора асинхронизированного турбогенератора

In this paper, a Volume-of-Fluid (VOF)-based approach for the Direct Numerical Simulation (DNS) of reactive mass transfer in gas–liquid flows is described. At the interface, local thermodynamic equilibrium is assumed and modelled by Henry's law. First numerical simulation results are presented for non-reactive and reactive mass transfer from rising gas bubbles to a surrounding liquid. For the evaluation of reactive mass transfer simulations with a consecutive, competitive reaction system in the liquid, a local selectivity is employed

The unrestricted Skyrme-tensor time-dependent Hartree-Fock and its application to the nuclear response from spherical to triaxial nuclei

The nuclear time-dependent Hartree-Fock model formulated in the three-dimensional space,based on the full Skyrme energy density functional and complemented with the tensor force,is presented for the first time. Full self-consistency is achieved by the model. The application to the isovector giant dipole resonance is discussed in the linear limit, ranging from spherical nuclei (16O, 120Sn) to systems displaying axial or triaxial deformation (24Mg, 28Si, 178Os, 190W, 238U). Particular attention is paid to the spin-dependent terms from the central sector of the functional, recently included together with the tensor. They turn out to be capable of producing a qualitative change on the strength distribution in this channel. The effect on the deformation properties is also discussed. The quantitative effects on the linear response are small and, overall, the giant dipole energy remains unaffected. Calculations are compared to predictions from the (quasi)-particle random phase approximation and experimental data where available, finding good agreement

The effect of oxide precipitates on minority carrier lifetime in n-type silicon

Supersaturated levels of interstitial oxygen in Czochralski silicon can lead to the formation of oxide precipitates. Although beneficial from an internal gettering perspective, oxygen-related extended defects give rise to recombination which reduces minority carrier lifetime. The highest efficiency silicon solar cells are made from n-type substrates in which oxide precipitates can have a detrimental impact on cell efficiency. In order to quantify and to understand the mechanism of recombination in such materials, we correlate injection level-dependent minority carrier lifetime data measured with silicon nitride surface passivation with interstitial oxygen loss and precipitate concentration measurements in samples processed under substantially different conditions. We account for surface recombination, doping level, and precipitate morphology to present a generalised parameterisation of lifetime. The lifetime data are analysed in terms of recombination activity which is dependent on precipitate density or on the surface area of different morphologies of precipitates. Correlation of the lifetime data with interstitial oxygen loss data shows that the recombination activity is likely to be dependent on the precipitate surface area. We generalise our findings to estimate the impact of oxide precipitates with a given surface area on lifetime in both n-type and p-type silicon

Consistency of the multi-model CMIP5/PMIP3-past1000 ensemble

We present an assessment of the probabilistic and climatological consistency of the CMIP5/PMIP3 ensemble simulations for the last millennium relative to proxy-based reconstructions under the paradigm of a statistically indistinguishable ensemble. We evaluate whether simulations and reconstructions are compatible realizations of the unknown past climate evolution. A lack of consistency is diagnosed in surface air temperature data for the Pacific, European and North Atlantic regions. On the other hand, indications are found that temperature signals partially agree in the western tropical Pacific, the subtropical North Pacific and the South Atlantic. Deviations from consistency may change between sub-periods, and they may include pronounced opposite biases in different sub-periods. These distributional inconsistencies originate mainly from differences in multi-centennial to millennial trends. Since the data uncertainties are only weakly constrained, the f.©Author(s) 2013

Исследование спектральных свойств когерентного дифракционного излучения от периодических структур

При пролете электрона вблизи периодической структуры генерируется поляризационное излучение, называемое дифракционным излучением от периодических структур (grating diffraction radiation). При пролете электрона параллельно решетке возникает хорошо изученное излучение Смита-Парселла. Однако при непараллельном пролёте также может возникать излучение. В данной работе проводится анализ спектральных характеристик когерентного дифракционного излучения от решеток, экспериментально полученных на ускорителе KEK-LUCX (г. Цукуба, Япония). Представлены спектры излучения, получаемые при разных углах ориентации решетки. Полученные спектральные характеристики сравниваются с теоретически рассчитанными.When an electron passes close to the periodic structure polarization radiation is generated, called diffraction radiation from periodic structures (grating diffraction radiation). When an electron passes parallel to the grating, well-studied Smith-Purcell radiation arises. However, in the case of a nonparallel flight, radiation can also occur. In this work, we analyze the spectral characteristics of coherent diffraction radiation from gratings, experimentally obtained at the accelerator KEK-LUCX (Tsukuba, Japan). Radiation spectrums obtained at different angles of grating orientation are presented. The obtained spectral characteristics are compared with theoretically calculated