Parabolic equations of Von Karman type on Kähler manifolds

We study a parabolic version of a system of Von Karman type on a compact Kähler manifold of arbitrary dimension. We provide local in time regular solutions, which can be extended to global bounded ones if the data of the problem are small.     

Molecule-to-metal bonds: electrografting polymers on conducting surfaces.

Electrografting is a powerful and versatile technique for modifying and decorating conducting surfaces with organic matter. Mainly based on the electro-induced polymerization of dissolved electro-active monomers on metallic or semiconducting surfaces, it finds applications in various fields including biocompatibility, protection against corrosion, lubrication, soldering, functionalization, adhesion, and template chemistry. Starting from experimental observations, this Review highlights the mechanism of the formation of covalent metal-carbon bonds by electro-induced processes, together with major applications such as derivatization of conducting surfaces with biomolecules that can be used in biosensing, lubrication of low-level electrical contacts, reversible trapping of ionic waste on reactive electrografted surfaces as an alternative to ion-exchange resins, and localized modification of conducting surfaces, a one-step process providing submicrometer grafted areas and which is used in microelectronics.     

Orthogonal polynomials on the unit circle and their derivatives

We characterize the sequences of orthogonal polynomials on the unit circle whose derivatives are also orthogonal polynomials on the unit circle. Some relations for the sequences of derivatives of orthogonal polynomials are provided. Finally, we pose some problems about orthogonality-preserving maps and differential equations for orthogonal polynomials on the unit circle.     

Incremental unknowns preconditioning for solving the Helmholtz equation

An efficient preconditioner is developed for solving the Helmholtz problem in both high and low frequency (wavenumber) regimes. The preconditioner is based on hierarchical unknowns on nested grids, known as incremental unknowns (IU). The motivation for the IU preconditioner is provided by an eigenvalue analysis of a simplified Helmholtz problem. The performance of our preconditioner is tested on the iterative solution of two‐dimensional electromagnetic scattering problems. When compared with other well‐known methods, our technique is shown to often provide a better numerical efficacy and, most importantly, to be more robust. Moreover, for the best performance, the number of IU levels used in the preconditioner should be designed for the coarsest grid to have roughly two points per linear wavelength. This result is consistent with the conventional sampling criteria for wave phenomena in contrast with existing IU applications for solving the Laplace/Poisson problem, where the coarsest grid comprises just one interior point. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007     

Excess noise in AlGaAs/GaAs heterojunction bipolar transistors andassociated TLM test structures

Noise measurements both on transmission line model (TLM) test structures and on associated HBT's are presented. Contact noise is proved to be negligible in the TLM's related to the base structure of transistors. A Hooge parameter for p⁺⁺ doped GaAs is extracted. Activation energies are calculated from results versus temperature. Considering the TLM related to the structure of the emitter, it is shown that the g-r levels observed originate from the AlGaAs layer. Noise measurements on HBT's also exhibit excess noise. A value of the cutoff frequency between the equivalent input current white noise and the 1/f component is given. The base current dependencies associated with different measurement configurations suggest the 1/f noise to come from the base or the emitter-base junction. The g-r components are studied as a function of temperature. Activation energies are deduced. Finally a comparison of the TLM and HBT noise results is presented. The presence of the complex DX center and of g-r levels in the base region are proposed as possible origins for the g-r noise in HBT's     

车载视觉武装司机

使车载视觉变成现实的大部分必要技术已经问世。未来,我们将看到具有视觉功能、为司机提建议、甚至自动对道路、交通状况以及天气变化做出响应的汽车。其中两种关键技术,即能够把原始图像转换成可用信息的数码     

Une architecture massivement parallèle intégrée

This paper presents a new massively parallel MIMD architecture, halfway between the Connection Machine and hypercubes based on 32-bit processors. It is built from specific 8-bit processors arranged in a 2-D grid and communicating by message transfers. We discuss the communication problems, the instruction set of the basic processing unit, the programmation of the whole array and the use of a high level data-flow language.