5,106 research outputs found
Non-adiabatic pulsations in ESTER models
One of the greatest challenges in interpreting the pulsations of rapidly
rotating stars is mode identification, i.e. correctly matching theoretical
modes to observed pulsation frequencies. Indeed, the latest observations as
well as current theoretical results show the complexity of pulsation spectra in
such stars, and the lack of easily recognisable patterns. In the present
contribution, the latest results on non-adiabatic effects in such pulsations
are described, and we show how these come into play when identifying modes.
These calculations fully take into account the effects of rapid rotation,
including centrifugal distortion, and are based on models from the ESTER
project, currently the only rapidly rotating models in which the energy
conservation equation is satisfied, a prerequisite for calculating
non-adiabatic effects. Non-adiabatic effects determine which modes are excited
and play a key role in the near-surface pulsation-induced temperature
variations which intervene in multi-colour amplitude ratios and phase
differences, as well as line profile variations.Comment: Proceedings for the Joint TASC2 & KASC9 Workshop, Terceira, Azores,
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Constitutional Law - Mississippi\u27s Recognition of a Privacy Right to Refuse Medical Treatment - In re Brown
Note
What determines euro area bank CDS spreads ?
This paper decomposes the explained part of the CDS spread changes of 31 listed euro area banks according to various risk drivers. The choice of the credit risk drivers is inspired by the Merton (1974) model. Individual CDS liquidity and other market and business variables are identified to complement the Merton model and are shown to play an important role in explaining credit spread changes. Our decomposition reveals, however, highly changing dynamics in the credit, liquidity, and business cycle and market wide components. This result is important since supervisors and monetary policy makers extract different signals from liquidity based CDS spread changes than from business cycle or credit risk based changes. For the recent financial crisis, we confirm that the steeply rising CDS spreads are due to increased credit risk. However, individual CDS liquidity and market wide liquidity premia played a dominant role. In the period before the start of the crisis, our model and its decomposition suggest that credit risk was not correctly priced, a finding which was correctly observed by e.g. the International Monetary Fundcredit default spreads, credit risk, financial crisis, financial sector, liquidity premia, structural model
Novel circuit models of arbitrary-shape line: Application to parallel coupled microstrip filters with suppression of multi-harmonic responses
International audienceFollowing a hierarchical approach, several models are built in microwave-circuit design software to simulate and design many configurations of arbitrary-shape line. The global shape is controlled by a cubic spline interpolation; our purpose is, indeed, to make easier the handling of nonuniform structure for microwave device designers. To illustrate the potentialities of these new components, we designed a third-order bandpass coupled-line filter at 5.5 GHz. A sinusoidal strip-width perturbation is applied by using the new model of nonuniform symmetrical coupled-line. Associated to over-coupling of the resonator end, the first three spurious passbands are then suppressed
Spurious Responses Suppression of Parallel Coupled-Lines Microstrip Bandpass Filters: Comparison and Improvements of Planar Approaches
International audienceIn this paper, three methods to reject the first spurious harmonic in parallel-coupled microstrip filters are investigated. The authors proposed an extension of these approaches to also suppress the second unwanted passbands while keeping the initial passband practically unchanged. Then, two of these techniques are combined to achieve a wider upper stopband. Indeed, the sinusoidal perturbation technique is well combined with overcoupled end sections to reject the first three spurious passbands of an order three filter. A comparison of simulations and experimental results is made, with a discussion on each method efficiency and possible applications to higher order filters
Les consĂ©quences du dĂ©boisement dâun versant sur la morphologie dâun petit cours dâeau
Le dĂ©boisement d'une partie d'un bassin-versant entraĂźne souvent une augmentation du dĂ©bit du cours d'eau, ce qui se traduit par des changements de la morphologie du lit. Il est dĂ©montrĂ© ici que des changements morphologiques et sĂ©dimentaires du lit d'un cours d'eau peuvent se produire sans que le dĂ©bit ne soit nĂ©cessairement augmentĂ©. L'Ă©tude porte sur un petit cours d'eau situĂ© en Estrie (QuĂ©bec). Le cours d'eau passe d'une zone forestiĂšre Ă une zone dĂ©boisĂ©e, mais d'un seul cĂŽtĂ©. Dans chacun des milieux, la forme du cours d'eau a Ă©tĂ© relevĂ©e et les dĂ©bits ont Ă©tĂ© mesurĂ©s. Les dĂ©bits sont demeurĂ©s stables, car la parcelle dĂ©boisĂ©e est de faible pente, de petite taille et irrĂ©guliĂšre en surface. Cependant, la forme de la coupe transversale est modifiĂ©e. Ainsi, le lit est symĂ©trique sous forĂȘt et est asymĂ©trique en milieu dĂ©boisĂ©. Par contre, la taille du cours d'eau n'a pas changĂ©. Le changement morphologique s'accompagne d'une diminution de la taille des sĂ©diments. Ces effets sont liĂ©s Ă des modifications hydrologiques observĂ©es au pied du versant oĂč une zone saturĂ©e existe maintenant en permanence. Au cours des prĂ©cipitations, le ruissellement superficiel Ă©rode et entaille les berges. Ces derniĂšres s'affaissent, d'oĂč la forme asymĂ©trique de la coupe transversale.Logging of part of a watershed often yields an increase in discharge and is responsible for important changes of the stream's morphology. In this paper, we show that an increase in discharge following logging operations is not necessary to produce changes in channel form. We have studied a small stream channel located in the Eastern Townships (QuĂ©bec). The stream flows from a forested to a logged area. Logging took place on one side of the stream. Channel form and water discharge were surveyed in each zone. Discharges are not significantly increased in the logged area. This result is explained by the gentleness and the small size of the logged hillslope. Channel form, however, is modified as a result of logging. The cross-section is symmetrical under forest cover and asymmetrical in the logged area. Particle size also declines from the forested to the logged area. These effects are caused by hydrologie modifications occurring at the foot of the logged hillslope which is permanently saturated. Thus, saturated overland flow is increased in the vicinity of the banks which are eroded by small rills and seapage. As a result, the banks are lowered and the cross-section becomes asymmetrical
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