Mean field limit for bosons and propagation of Wigner measures

We consider the N-body Schr\"{o}dinger dynamics of bosons in the mean field limit with a bounded pair-interaction potential. According to the previous work \cite{AmNi}, the mean field limit is translated into a semiclassical problem with a small parameter $\epsilon\to 0$, after introducing an $\epsilon$-dependent bosonic quantization. The limit is expressed as a push-forward by a nonlinear flow (e.g. Hartree) of the associated Wigner measures. These object and their basic properties were introduced in \cite{AmNi} in the infinite dimensional setting. The additional result presented here states that the transport by the nonlinear flow holds for rather general class of quantum states in their mean field limit.Comment: 10 page

Enhancement of near-cloaking. Part II: the Helmholtz equation

The aim of this paper is to extend the method of improving cloaking structures in the conductivity to scattering problems. We construct very effective near-cloaking structures for the scattering problem at a fixed frequency. These new structures are, before using the transformation optics, layered structures and are designed so that their first scattering coefficients vanish. Inside the cloaking region, any target has near-zero scattering cross section for a band of frequencies. We analytically show that our new construction significantly enhances the cloaking effect for the Helmholtz equation.Comment: 16pages, 12 fugure

Promotion effect in Pt–ZnO catalysts for selective hydrogenation of crotonaldehyde to crotyl alcohol: A structural investigation

Pt–ZnO catalysts prepared from different precursors, H2PtCl6 and Pt(NH3)4(NO3)2, and reduced at increased temperatures are used to achieve high selectivity towards crotyl alcohol in hydrogenation of crotonaldehyde. The ex-chloride catalyst shows a higher activity and selectivity than the ex-nitrate one. Transmission electron microscopy, electron diffraction, high-resolution imaging, energy dispersive X-ray spectroscopy and element mapping are used to characterize the catalysts in order to correlate the microstructure to the catalytic behavior. PtZn alloy formation is confirmed for both ex-chloride and exnitrate catalysts reduced at 673 K. The metal particles in ex-nitrate catalyst are smaller in size than those in ex-chloride. Inmost aggregates of the ex-chloride catalyst, chlorine is distributed homogeneously with low concentration (<1%). The higher chlorine concentration in some region leads to local morphology and microstructure changes. Influences of the observed structural features such as alloy formation, particle size difference, formation of ill-defined material, and chlorine distribution are discussed

Exponential stability of the wave equation with memory and time delay

We study the asymptotic behaviour of the wave equation with viscoelastic damping in presence of a time-delayed damping. We prove exponential stability if the amplitude of the time delay term is small enough

Local Analysis of Inverse Problems: H\"{o}lder Stability and Iterative Reconstruction

We consider a class of inverse problems defined by a nonlinear map from parameter or model functions to the data. We assume that solutions exist. The space of model functions is a Banach space which is smooth and uniformly convex; however, the data space can be an arbitrary Banach space. We study sequences of parameter functions generated by a nonlinear Landweber iteration and conditions under which these strongly converge, locally, to the solutions within an appropriate distance. We express the conditions for convergence in terms of H\"{o}lder stability of the inverse maps, which ties naturally to the analysis of inverse problems

Poly[[chlorido-(1,10-phenanthroline-κ2N,N′)copper(II)]-μ3-1,1,3,3-tetra-cyano-2-eth-oxy-propenido- κ3N:N′:N′′] : coordination polymer sheets linked into bilayers by hydrogen bonds

The authors acknowledge the Algerian DG–RSDT (Direction Generale de la Recherche Scientifique et du Developpement Technologique) and the Algerian ATRST (Agence Thematique de Recherche en Sciences et Technologie; PNR project) for financial support. ZS thanks Sandra Lebaroud for her help in preparing the manuscript and the Unit of Support for Technical and Scientific Research (UATRS, CNRST) for the X-ray measurements.In the title compound, [Cu(C9H5N4O)Cl(C12H8N2)] n or [Cu(tcnoet)Cl(phen)] n , where phen is 1,10-phenanthroline and tcnoet is 1,1,3,3-tetra-cyano-2-eth- oxy-propenide, the axially elongated (4 + 2) coordination polyhedron around the CuII centre contains N atoms from three different tcnoet ligands. The resulting coordination polymer takes the form of sheets which are linked in pairs by a single C - H⋯N hydrogen bond to form bilayers. The bond lengths provide evidence for significant bond fixation in the phen ligand and extensive electronic delocalization in the tcnoet ligand, where the two -C(CN)2 units are rotated, in conrotatory fashion, out of the plane of the central C3O fragment.Publisher PDFPeer reviewe

Interior Regularity Estimates in High Conductivity Homogenization and Application

In this paper, uniform pointwise regularity estimates for the solutions of conductivity equations are obtained in a unit conductivity medium reinforced by a epsilon-periodic lattice of highly conducting thin rods. The estimates are derived only at a distance epsilon^{1+tau} (for some tau>0) away from the fibres. This distance constraint is rather sharp since the gradients of the solutions are shown to be unbounded locally in L^p as soon as p>2. One key ingredient is the derivation in dimension two of regularity estimates to the solutions of the equations deduced from a Fourier series expansion with respect to the fibres direction, and weighted by the high-contrast conductivity. The dependence on powers of epsilon of these two-dimensional estimates is shown to be sharp. The initial motivation for this work comes from imaging, and enhanced resolution phenomena observed experimentally in the presence of micro-structures. We use these regularity estimates to characterize the signature of low volume fraction heterogeneities in the fibred reinforced medium assuming that the heterogeneities stay at a distance epsilon^{1+tau} away from the fibres

Underwater robots equipped with artificial electric sense for the exploration of unconventional aquatic niches

International audienceThis article presents different use of the electric field perception in the context of underwater robot navigation. To illustrate the developed navigation behaviours we will introduce a recently launched european project named subCULTron and will show some simulation and experimentation results. The project sub- CULTron aims at achieving long-term collective robot exploration and monitoring of underwater environments. The demonstration will take place in the lagoon of Venice, a large shallow embayment composed of salt turbib water that represents a challenging environment for underwater robots as common sensor like vision or acoustic are difficult to handle. To overcome turbidity and confinement problems our robots will be equipped with artificial electric sensors that will be used as the main sensorial modality for navigation. Electric sense is a bio-inspired sense that has been developed by several species of fish living in turbib and confined underwater environment. In this paper, many different robotic behaviours based on the electric field perception will be presented, in particular we will address reactive navigation, object/robots detection, and object localization and estimation

Measuring Farmland Biodiversity

Despite close interaction between agriculture and biodiversity—farms cover one-third of the world’s land surface—little is empirically known about the ecological effects of different farming practices. About one-third of the world’s land surface is used for farming, a fact that bears important implications for biodiversity. In Europe, for instance, an estimated 50 percent of all wild species are reliant on agricultural habitats, while agricultural productivity often depends on the presence or absence of particular species. Despite this close coupling, surprisingly little is known about the status and evolution of farmland biodiversity. A team of European and African researchers, hoping to fill this gap in information, recently invented and piloted a new toolbox called the BioBio indicator set, which measures 23 different instances of biodiversity across a variety of farm types and scales in Europe. Applications were also tested in Tunisia, Ukraine, and Uganda, where they proved a feasible starting point for adaptation to the agricultural context of different countrie