Maximum time step for the BDF3 scheme applied to gradient flows

For backward differentiation formulae (BDF) applied to gradient flows of semiconvex functions, quadratic stability implies the existence of a Lyapunov functional. We compute the maximum time step which can be derived from quadratic stability for the 3-step BDF method (BDF3). Applications to the asymptotic behaviour of sequences generated by the BDF3 scheme are given

Generation and characterization of T40/A5754 interfaces with lasersPatrice

Laser-induced reactive wetting and brazing of T40 titanium with A5754 aluminum alloy with 1.5 mm thickness was carried out in lap-joint configuration, with or without the use of Al5Si filler wire. A 2.4 mm diameter laser spot was positioned on the aluminum side to provoke spreading and wetting of the lower titanium sheet, with relatively low scanning speeds (0.1–0.6 m/min). Process conditions did not play a very significant role on mechanical strengths, which were shown to reach 250–300 N/mm on a large range of laser power and scanning speeds. In all cases considered, the fracture during tensile testing occurred next to the TiAl3 interface, but in the aluminum fusion zone. The interfacial resistance was then evaluated with the LASAT bond strength tester, based upon the generation and propagation of laser-induced shock waves. A 0.68 GPa uniaxial bond strength was estimated for the T40/A5754 interface under dynamic loading conditions

Monetary policy transmission in the euro area: what do aggregate and national structural models tell us?

This paper analyses the monetary transmission mechanism in the euro area through the use of large scale macroeconomic models at the disposal of the European Central Bank and the National Central Banks of the Eurosystem. The results reported are based on a carefully designed common simulation experiment involving a 100 basis point rise in the policy interest rate for two years accompanied by common assumptions regarding the path of longterm interest rates and the exchange rate. Aggregating the country level results, the fall in output is found to reach a maximum of 0.4 per cent after 2 years. The maximum aggregate fall in prices is also 0.4 per cent, but it occurs 2 years later. The dominant channel of transmission in the first two years is the exchange rate channel, but in terms of the impact on output, the user cost of capital channel becomes dominant from the third year of the simulation onwards.monetary policy transmission mechanism, macroeconomic models

A DOUBLY SPLITTING SCHEME FOR THE CAGINALP SYSTEM WITH SINGULAR POTENTIALS AND DYNAMIC BOUNDARY CONDITIONS

We propose a time semi-discrete scheme for the Caginalp phase-field system with singular potentials and dynamic boundary conditions. The scheme is based on a time splitting which decouples the equations and on a convex splitting of the energy associated to the problem. The scheme is unconditionally uniquely solvable and the energy is nonincreasing if the time step is small enough. The discrete solution is shown to converge to the energy solution of the problem as the time step tends to 0. The proof involves a multivalued operator and a monotonicity argument. This approach allows us to compute numerically singular solutions to the problem

Monetary policy transmission in the euro area: What do aggregate and national structural models tell us?

This paper analyses the monetary transmission mechanism in the euro area through the use of large scale macroeconomic models at the disposal of the European Central Bank and the National Central Banks of the Eurosystem. The results reported are based on a carefully designed common simulation experiment involving a 100 basis point rise in the policy interest rate for two years accompanied by common assumptions regarding the path of long-term interest rates and the exchange rate. Aggregating the country level results, the fall in output is found to reach a maximum of 0.4% after 2 years. The maximum aggregate fall in prices is also 0.4%, but it occurs 2 years later. The dominant channel of transmission in the first two years is the exchange rate channel, but in terms of the impact on output, the user cost of capital channel becomes dominant from the third year of the simulation onwards JEL Classification: C50, E17, E5macroeconomic models, Monetary policy transmission mechanism

DRAG-FREE FLOW OVER A SUBMERGED RANKINE BODY

We prove the existence of a family of immersed obstacles which have zero wave resistance in the context of the two-dimensional Neumann-Kelvin problem. We first build a waveless potential by superposing a source and a sink in a uniform flow, for an appropriate choice of parameters. The obstacle is obtained by a combination of streamlines of the waveless potential. Numerical simulations show that the construction is valid for a large set of parameters

A theoretical and numerical determination of optimal ship forms based on Michell's wave resistance

We determine the parametric hull of a given volume which minimizes the total water resistance for a given speed of the ship. The total resistance is the sum of Michell's wave resistance and of the viscous resistance, approximated by assuming a constant viscous drag coefficient. We prove that the optimized hull exists, is unique, symmetric, smooth and that it depends continuously on the speed. Numerical simulations show the efficiency of the approach, and complete the theoretical results

REMARKS ON THE ASYMPTOTIC BEHAVIOR OF SCALAR AUXILIARY VARIABLE (SAV) SCHEMES

We introduce a time semi-discretization of a damped wave equation by a SAV scheme with second order accuracy. The energy dissipation law is shown to hold without any restriction on the time step. We prove that any sequence generated by the scheme converges to a steady state (up to a subsequence). We notice that the steady state equation associated to the SAV scheme is a modified version of the steady state equation associated to the damped wave equation. We show that a similar result holds for a SAV fully discrete version of the Cahn-Hilliard equation and we compare numerically the two steady state equations

Revisiting the Jurassic Geomagnetic Reversal recorded in the Lesotho Basalt (Southern Africa)

We carried out a detailed and continuous paleomagnetic sampling of the reversed to normal geomagnetic transition recorded by some 60 consecutive flow units near the base of the Lesotho Basalt (183  1 Ma). After alternating field or thermal cleaning the directions of remanence are generally well clustered within flow units. In contrast, the thermal instability of the samples did not allow to obtain reliable paleointensity determinations. The geomagnetic transition is incompletely recorded due to a gap in volcanic activity attested both by eolian deposits and a large angular distance between the field directions of the flows underlying or overlying these deposits. The transition path is noticeably different from that reported in the pioneer work of van Zijl et al. (1962). The most transitional Virtual Geomagnetic Poles are observed after the volcanic hiatus. Once continents are replaced in their relative position 180 Ma ago, the post-hiatus VGP cluster over Russia. However, two successive rebounds from that cluster are found, with VGP reaching repeatedly Eastern Asia coast. Thus, the VGP path is not narrowly constrained in paleolongitude. The decrease in intensity of magnetization as the field deviates from the normal or reversed direction suggests that the decrease in field magnitude during the reversal reached 80-90%. We conclude that although the reversal is of a dipole of much weaker moment than that which existed on average during Cenozoic time, the characteristics of the reversing geodynamo seem to be basically similar.Comment: Paper No GD124 submitted to Geophysical Journal International. Received in original form 20/01/2003, accepted 09/04/200

Influence of statin use on clinicopathological characteristics of localized prostate cancer and outcomes obtained after radical prostatectomy: a single center study

To assess the impact of statin use on biochemical recurrence (BCR) of prostate cancer after radical prostatectomy (RP)