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This paper concerns the use of a point-value multiresolution algorithm and its extension to three-dimensional hyperbolic conservation laws. The proposed method is applied to a high-order finite-differences discretization with an explicit time integration. The fluxes are evaluated on the adaptive grid using a fifth-order high-resolution shock capturing scheme based on a WENO solver, while the time is advanced using a third-order Runge–Kutta scheme. The multiresolution prediction operators are presented for one-, two- and three-dimensional problems. To assess the efficiency and the accuracy of the method, a new tolerance-scale diagram is introduced. This diagram enables to properly choose the adequate value of the tolerance in order to maintain an optimal multiresolution quality. Numerical examples based on advection and Euler equations are carried out to show that the proposed method yields accurate results. [ABSTRACT FROM AUTHOR]

Abstract: In this work, we present a study on CuIn(S,Se)2 absorbers prepared by electrodeposition followed by rapid thermal annealing promising to lower manufacturing cost. However the annealed material contains copper sulpho-selenide of Cu(S y ,Se1− y ) type which is harmful for the electrical properties of photovoltaic devices. These phases are removed by a cyanide etching. Because of an intrinsic variability of absorber fabrication process, the presented survey is based on statistic approach. We highlighted the influence of a cyanide treatment on surface and bulk compositions. The surface composition follows a distribution according to a Cu(S,Se)–CuIn(S,Se)2 system and the bulk composition agrees with Cu(S,Se)2–CuIn3(S,Se)5 system. Moreover, surface composition can be modified by adjusting the cyanide concentrations of etching solution without any changes in the bulk one. It ensues that Cu(S,Se) is not only present on the surface but also in the bulk of samples. [Copyright &y& Elsevier]

A comparison between two different ways of extracting coherent vortices in three-dimensional (3D) homogeneous isotropic turbulence is performed, using either orthogonal or biorthogonal wavelets. The method is based on a wavelet decomposition of the vorticity field and a subsequent thresholding of the wavelet coefficients. The coherent vorticity is reconstructed from a few strong wavelet coefficients, while the incoherent vorticity is reconstructed from the remaining weak coefficients. The choice of the threshold, which has no adjustable parameters, is motivated for the orthogonal case from the denoising theory. Using only 3 % of the coefficients we show that both decompositions, that is orthogonal and biorthogonal, extract the coherent vortices. They contain most of the energy (around 99 % in both cases) and retain 74 % and 68 % of the enstrophy in the orthogonal and biorthogonal cases, respectively. The incoherent background flow for the orthogonal decomposition, which corresponds to 97 % of the wavelet coefficients, is structureless, decorrelated, and has a Gaussian velocity probability distribution function (PDF). In contrast, for the biorthogonal decomposition, the background flow exhibits quasi-two-dimensional (2D) structures and yields an exponential velocity PDF. Moreover, the biorthogonal decomposition loses 3.7% of both enstrophy and helicity, while they are conserved by the orthogonal decomposition. [ABSTRACT FROM AUTHOR]

In this paper, a fully adaptive multiresolution (MR) finite difference scheme with a time-varying tolerance is developed to study compressible fluid flows containing shock waves in interaction with solid obstacles. To ensure adequate resolution near rigid bodies, the MR algorithm is combined with an immersed boundary method based on a direct-forcing approach in which the solid object is represented by a continuous solid-volume fraction. The resulting algorithm forms an efficient tool capable of solving linear and nonlinear waves on arbitrary geometries. Through a one-dimensional scalar wave equation, the accuracy of the MR computation is, as expected, seen to decrease in time when using a constant MR tolerance considering the accumulation of error. To overcome this problem, a variable tolerance formulation is proposed, which is assessed through a new quality criterion, to ensure a time-convergence solution for a suitable quality resolution. The newly developed algorithm coupled with high-resolution spatial and temporal approximations is successfully applied to shock-bluff body and shock-diffraction problems solving Euler and Navier-Stokes equations. Results show excellent agreement with the available numerical and experimental data, thereby demonstrating the efficiency and the performance of the proposed method. [ABSTRACT FROM AUTHOR]

Abstract The underlying sequential behavior of the multiresolution (MR) method has been exploited for parallel computing by introducing a concept of multiresolution forest structures (MFS) along with two new load-balancing algorithms. Another easy-to-implement multithreading approach has also been introduced for the multicore architectures. Tests were conducted using an Euler solver based on a fifth-order shock capturing WENO scheme and a third-order Runge–Kutta algorithm. The methods have been rigorously analyzed in terms of speedup ratio and parallel efficiency to bring forth their benefits as well as limitations. The performance yielded through these methods indicates that the MFS is a new headway for the MR method in parallel computing that has a potential to harness better scalability. Highlights • Three novel multiresolution (MR) parallel load-balancing algorithms are developed. • Algorithms are based on OpenMP, MPI and OpenMP–MPI hybrid each. • New concept of multiresolution forest structure (MFS) is proposed. • The proposed algorithms are suited for speedup performance enhancement of MR methods. [ABSTRACT FROM AUTHOR]

Abstract: In this work we investigate the electronic properties of Glass/Mo/Cu(In,Ga)Se2 (CIGS)/CdS/ZnO solar cells where the co-evaporated CIGS surfaces are subjected to a two steps chemical treatment. This two steps treatment consisting of a strong oxidative etch (bromine) of the absorber surface followed by a cyanide treatment leads to a significant (by 30%) improvement of the photovoltaic performances. The bromine etching time is used as variable in the study, while admittance spectroscopy is employed for electrically active defects characterization. Particular attention was given to the interpretation of the origin of the defects probed in the samples. One type of defects with activation energy ranging between 0.2 eV to 0.5 eV, commonly probed in the CIGS based devices and labelled N2, are passivated by the cyanide treatment. This allowed us to propose a new interpretation concerning the nature of this type of defect. [Copyright &y& Elsevier]

Abstract: The CIS by electrodeposition (CISEL) project between Electricité de France (EDF), Centre National de la Recherche Scientifique (CNRS)/Ecole Nationale Supérieure de Chimie de Paris (ENSCP) and Saint-Gobain Recherche (SGR) aims at developing a low-cost electrodeposition process for Cu(In,Ga)(S,Se)2 (CIGS) solar cells. The process is characterized by two main steps: (i) deposition of the precursor film and (ii) thermal annealing. This process enables the preparation of a large range of sulfur containing absorbers, with S/(S+Se) atomic ratio from 0% to more than 90%. The films are single phase over the whole composition range. The influence of Sulfur content on the microstructure has been shown with grain sizes decreasing with increasing sulfur content. Efficient solar cells can be obtained from all the different precursor compositions, with efficiencies of over 10% on lab cells on sulfur-rich absorbers, and 6–7% on 30×30 cm2 devices. The homogeneity of 15×15 cm2 substrates is also discussed. [Copyright &y& Elsevier]

Abstract: This paper reviews the state of the art in using electrodeposition to prepare chalcopyrite absorber layers in thin film solar cells. Most of the studies deal with the direct preparation of Cu(In,Ga)Se2 films, and show that the introduction of gallium in the films is now becoming possible from single bath containing all the elements. Electrodeposition can also be used to form precursor films with stacked layer structures, of pure elements or of combinations with binary or even ternary films. Thermal annealing treatments are of dramatic importance to provide suitable electronic quality to the layers. They are often done in the presence of a chalcogen (selenium or sulfur) over pressure and there is a tendency to use rapid thermal processes. Less studies are devoted to complete solar cell formation. Significant progresses have been made in the recent period with several groups achieving cell efficiencies around 8–10% on different substrates. A record efficiency of 11.3% is reported for a cell with an absorber presenting a band gap of 1.47eV. First results on the manufacturability of the corresponding process to large areas are presented. [Copyright &y& Elsevier]