Critical state analysis of orthogonal flux interactions in pinned superconductors

We show that, based on the critical state model for flux-line pinning in hard superconductors, one can assess the magnetic moment relaxation induced by the oscillations of a perpendicular magnetic field. Our theory follows a recent proposal of using phenomenological 2D modeling for the description of crossed field dynamics in high-T$_c$ superconductors [{\tt arXiv:cond-mat/0703330}]. Stationary regimes with either saturation to metastable configurations, or complete decay to the thermodynamic equilibrium are obtained. The transition between both types of response is related to the disappearance of a flux free core within the sample. As a common feature, a step-like dependence in the time relaxation is predicted for both cases. The theory may be applied to long bars of arbitrary and non homogeneous cross section, under in-plane magnetic field processes.Comment: 11 figures, submitte

One-dimensional relativistic dissipative system with constant force and its quantization

For a relativistic particle under a constant force and a linear velocity dissipation force, a constant of motion is found. Problems are shown for getting the Hamiltoninan of this system. Thus, the quantization of this system is carried out through the constant of motion and using the quantization of the velocity variable. The dissipative relativistic quantum bouncer is outlined within this quantization approach.Comment: 11 pages, no figure

Scattering approach to fidelity decay in closed systems and parametric level correlations

This paper is based on recent work which provided an exact analytical description of scattering fidelity experiments with a microwave cavity under the variation of an antenna coupling [K\"ober et al., Phys. Rev. E 82, 036207 (2010)]. It is shown that this description can also be used to predict the decay of the fidelity amplitude for arbitrary Hermitian perturbations of a closed system. Two applications are presented: First, the known result for global perturbations is re-derived, and second, the exact analytical expression for the perturbation due to a moving S-wave scatterer is worked out. The latter is compared to measured data from microwave experiments, which have been reported some time ago. Finally, we generalize an important relation between fidelity decay and parametric level correlations to arbitrary perturbations.Comment: 20 pages, 2 figures, research article, (v2: stylistic changes, ref. added

State of the art of pricing policy in air transportation: network carriers vs. low-cost airlines

The modern air transport industry is highly competitive. To survive in the market, the implementation of a successful marketing strategy is fundamental. In particular, an effective pricing policy has become crucial for airlines to remain profitable. Correspondingly, the different types of airline in the market have also established very distinct pricing policies. The present study is based on a literature review and presents the state of the art of pricing policy in air transportation. The aim is to compare and discuss the pricing strategies of network carriers and low-cost airlines. Special attention is paid to Revenue Management, which is a very important management tool used by airlines to take advantage of the differences in willingness to pay of passengers. The pricing policy, however, depends on the overall business strategy of the airline. Results show many differences, resulting from the fact that these two types of airline are characterized by very different fundamental business models and, correspondingly, also target groups. Since network carriers and also low-cost airlines have adjusted their pricing strategies lately, these recent developments will be discussed as well. This paper adds to the knowledge of this topic because it presents the most up-to-date and complete study on pricing regarding network carriers vs. low-cost airlines.A moderna indústria do transporte aéreo é altamente competitiva. Para sobreviver no mercado, a implementação de uma estratégia de marketing bem-sucedida é fundamental. Em particular, uma política de preços eficaz tornou-se crucial para as companhias aéreas continuarem lucrativas. Os diferentes tipos de companhias aéreas no mercado também estabeleceram políticas de preços muito distintas. O presente estudo baseia-se numa revisão da literatura e apresenta o estado da arte da política de preços no transporte aéreo. O objetivo é comparar e discutir as estratégias de preços de companhias aéreas de linha e companhias aéreas de baixo custo. Atenção especial é dada à Gestão de Receitas (Revenue Management), que é uma ferramenta de gestão usada pelas companhias aéreas para aproveitar as diferenças na disposição de pagar dos passageiros. A política de preços, no entanto, depende da estratégia geral de negócios da companhia aérea. Os resultados mostram muitas diferenças, resultantes do facto de que esses dois tipos de companhias aéreas são caracterizados por modelos de negócios fundamentais muito diferentes e, correspondentemente, também grupos-alvo. Como as operadoras de rede e também as companhias aéreas de baixo custo ajustaram as suas estratégias de preços ultimamente, esses desenvolvimentos recentes também serão discutidos. Este documento contribui para o conhecimento deste tópico, pois apresenta o estudo mais atualizado e completo sobre preços de companhias aéreas de linha versus companhias aéreas de baixo custo.info:eu-repo/semantics/publishedVersio