Search results for " shocks"

On critical behaviour in generalized Kadomtsev-Petviashvili equations

2016

International audience; An asymptotic description of the formation of dispersive shock waves in solutions to the generalized Kadomtsev–Petviashvili (KP) equation is conjectured. The asymptotic description based on a multiscales expansion is given in terms of a special solution to an ordinary differential equation of the Painlevé I hierarchy. Several examples are discussed numerically to provide strong evidence for the validity of the conjecture. The numerical study of the long time behaviour of these examples indicates persistence of dispersive shock waves in solutions to the (subcritical) KP equations, while in the supercritical KP equations a blow-up occurs after the formation of the disp…

MHD modelling of plasma flowing in coronal magnetic channels

A numerical study of postshock oscillations in slowly moving shock waves

2003

Abstract Godunov-type methods and other shock capturing schemes can display pathological behavior in certain flow situations. This paper discusses the numerical anomaly associated to slowly moving shocks. We present a series of numerical experiments that illustrate the formation and propagation of this pathology, and allows us to establish some conclusions and question some previous conjectures for the source of the numerical noise. A simple diagnosis on an explicit Steger-Warming scheme shows that some intermediate states in the first time steps deviate from the true direction and contaminate the flow structure. A remedy is presented in the form of a new flux split method with an entropy i…

Bank-specific shocks and aggregate leverage: Empirical evidence from a panel of developed countries

2020

International audience; This paper investigates the link between shocks in the banking sector and aggregate leverage measured by the credit-to-GDP gap. Using a balanced panel of 15 countries for the period 1989–2016, we exploit the approach due to Gabaix (2011) and consider banking granular shocks as an indicator of banking distress. Using methods that account for potential endogeneity, we find that banking shocks Granger-cause aggregate leverage. In particular, banking shocks tend to increase the level of leverage and cause departures of the credit-to-GDP ratio from its long-term trend.

Cross-listing, price discovery and the informativeness of the trading process

2003

This paper analyzes the price discovery process of securities that trade at multiple markets with trading sessions that totally or partially overlap. Building on Hasbrouck (1995) information share approach, we introduce a methodology that distinguishes two sources of information asymmetries between markets: trade-related and trade-unrelated informative shocks. This approach determines how much of each market?s relative contribution to the price discovery process during the overlapping period is attributable to its own trading activity. We provide empirical evidence on the contribution of the NYSE in the price discovery process of the Spanish cross-listed stocks during the daily two-hour ove…

Etude numérique d'équations aux dérivées partielles non linéaires et dispersives

2011

Numerical analysis becomes a powerful resource in the study of partial differential equations (PDEs), allowing to illustrate existing theorems and find conjectures. By using sophisticated methods, questions which seem inaccessible before, like rapid oscillations or blow-up of solutions can be addressed in an approached way. Rapid oscillations in solutions are observed in dispersive PDEs without dissipation where solutions of the corresponding PDEs without dispersion present shocks. To solve numerically these oscillations, the use of efficient methods without using artificial numerical dissipation is necessary, in particular in the study of PDEs in some dimensions, done in this work. As stud…

Accretion shock on CTTSs and its X-ray emission

2009

High spectral resolution X-ray observations of classical T Tauri stars (CTTSs) demonstrate the presence of plasma at T~2-3×10^6 K and ne~10^11-10^13 cm-3. Stationary models suggest that this emission is due to shock-heated accreting material. We address this issue by a 1-D hydrodynamic model of the impact of the accretion flow onto a chromosphere of a CTTS with the aim of investigating the stability of accretion shock and the role of the chromosphere. Our simulations include the effects of gravity, radiative losses from optically thin plasma, the thermal conduction and a detailed modeling of the stellar chromosphere. Here we present the results of a simulation based on the parameters of the…

Monetary policy and exchange rate dynamics in the Spanish economy

1999

As the Spanish economy gets more integrated in international markets, the real exchange rate becomes a key determinant of the monetary transmission. In this paper we trace out the dynamic response of prices, output and the exchange rate following a monetary policy shock. We estimate a structural VAR model whose identification scheme is based on the long run properties common to a large class of models. The results suggest that a small model with efficient asset markets plus nominal inertia and long run monetary neutrality, captures the essential features of the monetary transmission mechanism in Spain. The interest rate shock is well identified and the exchange rate overshoots its long run …

Gender, Weather Shocks and Welfare: Evidence from Malawi

2017

This paper explores the gender-differentiated effects of weather shocks on households’ welfare in Malawi using panel data aligned with climatic records. Results show that temperature shocks severely affect household welfare, reducing consumption, food consumption and daily caloric intake. The negative welfare effects are more severe for households where land is solely managed by women, a finding that sheds light on the gender-unequal impact of temperature shocks. Our evidence also suggests that women’s vulnerability to temperature shocks is linked to women’s land tenure security, as temperature shocks impact significantly women’s welfare only in patrilineal districts, where statistics show …

Effect of long-term salinity increase on nitritation and denitritation kinetics in activated sludge and granular sludge reactors

2017

The aim of this work was to investigate the effects of moderate and drastic long-termincrease of salinity.Particularly, the study was aimed at assessing the shock effecton nitritationand denitritation kineticsof halophilic biomass inboth forms:flocculent activated sludge and granular sludge.