Two Dimensional Aggregation Procedure: An Alternative to the Matrix Algebraic Algorithm

The aggregation procedure is an important theoretical and empirical topic of economics. It appears in the Microeconomics and Macroeconomics, in Panel and Cross-Sectional Data Analysis, in Data Mining Analysis, in Input–Output and Agent-based Computational Economics Modelling. The question of the choice of algorithm is became important since the size of the sample data has became more important, and despite of the speed of the computers. In this paper we present the “classical” algorithm (the “matrix algebraic” one) of aggregation of the two-dimensional sample data, and compare it to the alternative algorithms (the “vectorial” one) we developed. Then we present some extensions to the multidimensional aggregation.      

Ignition and Charring of PVC-Based Electric Cables

Fire Technology - The ignition of four different PVC-based electric cables was studied using cone calorimeter and the influence of the charring phenomenon on ignition was investigated. The...     

Retrieval of microphysical and optical properties in aerosol plumes with hyperspectral imagery: L-APOM method

This paper presents the retrieval method L-APOM which aims at characterizing the microphysical and optical properties of aerosol plumes from hyperspectral images with high spatial resolution. The inversion process is divided into three steps: estimation of the ground reflectance below the plume, characterization of the standard atmosphere (gases and background aerosols) and estimation of the plume aerosols properties. As using spectral information only is not sufficient to insure uniqueness of solutions, original constraints are added by assuming slow spatial variations of particles properties within the plume. The whole inversion process is validated on a large set of simulated images and reveals to remain accurate even in the worst cases of noise: relative estimation errors of aerosol properties remain between 10% and 20% in most cases. L-APOM is applied on a real AVIRIS hyperspectral image of a biomass burning plume for which in situ measurements are available. Retrieved properties appear globally consistent with measurements.     

A Novel Constellation Shaping Technique for Bit-Interleaved Coded Modulation

We present a new and simple method which consists to apply constellation shaping to bit-interleaved turbo-coded modulation (BICTM) over additive white Gaussian noise channels. By assuming the example of a 3-bit/dim 16-PAM BITCM, it is shown that this technique can provide shaping gain of 0.79 dB.     

Predicting the Thermal Conductivity of AlSi/Polyester Abradable Coatings: Effects of the Numerical Method

The final target of this study is to achieve a better understanding of the behavior of thermally sprayed abradable seals such as AlSi/polyester composites. These coatings are used as seals between the static and the rotating parts in aero-engines. The machinability of the composite coatings during the friction of the blades depends on their mechanical and thermal effective properties. In order to predict these properties from micrographs, numerical studies were performed with different software packages such as OOF developed by NIST and TS2C developed at the UTBM. In 2008, differences were reported concerning predictions of effective thermal conductivities obtained with the two codes. In this article, a particular attention was paid to the mathematical formulation of the problem. In particular, results obtained with a finite difference method using a cell-centered approach or a nodal formulation allow explaining the discrepancies previously noticed. A comparison of the predictions of the computed effective thermal conductivities is thus proposed. This study is part of the NEWAC project, funded by the European Commission within the 6th RTD Framework programm (FP6).     

Biology-based modeling to analyze uranium toxicity data on Daphnia magna in a multigeneration study

Recent studies have investigated chronic toxicity of waterborne depleted uranium on the life cycle and physiology of Daphnia magna. In particular, a reduction in food assimilation was observed. Our aims here were to examine whether this reduction could fully account for observed effects on both growth and reproduction, for three successive generations, and to investigate through microscope analyses whether this reduction resulted from direct damage to the intestinal epithelium. We analyzed data obtained by exposing Daphnia magna to uranium over three successive generations. We used energy-based models, which are both able to fit simultaneously growth and reproduction and are biologically relevant. Two possible modes of action were compared - decrease in food assimilation rate and increase in maintenance costs. In our models, effects were related either to internal concentration or to exposure concentration. The model that fitted the data best represented a decrease in food assimilation related to exposure concentration. Furthermore, observations of consequent histological damage to the intestinal epithelium, together with uranium precipitates in the epithelial cells, supported the assumption that uranium has direct effects on the digestive tract. We were able to model the data in all generations and showed that sensitivity increased from one generation to the next, in particular through a significant increase of the intensity of effect, once the threshold for appearance of effects was exceeded.     

A sensitivity study for an indoor channel

The context of this paper is the 3D wave propagation simulation with a software based on a ray tracing technique in typical indoor environments. The presented works are complementary to these of the literature which propose the validation of a propagation model in comparison with measurements. Indeed, the presented study consists of a sensitivity analysis of an already validated propagation model. The considered parameters are electromagnetic, geometric and electric; they directly intervene in the two parts of a simulation: the modelling of the wave propagation and of the environment. The aim of this study is to contribute to the setting up of parameterisation rules of a simulation software according to two criteria: the accuracy and the compromise between accuracy and computation time.     

Une optimisation en temps de calcul pour la prédiction de zones de couverture radioélectriques

This article presents a method which optimises the computation time for the prediction of a radio coverage, whatever the propagation model used. The principle consists in reducing the number of application points of the propagation model in relation to a classical technique. The proposed method is based on a multi resolution analysis of measured signals carried out around 2 GHz, and on an electromagnetic analysis of the propagation environment. The performances of the method are evaluated in term of reduction in computation time and of accuracy, in comparaison with the classical technique.     

New alginate foams: Box‐Behnken design of their manufacturing; fire retardant and thermal insulating properties

A new method for preparing alginate foams with progressive release of copper in the presence of sodium lauryl sulfate (SLS, foaming agent) has been designed. Copper acts as the ionotropic gelling agent through the reaction of copper carbonate with gluconolactone. The process does not require freeze‐drying contrarily to the conventional method used for preparing macroporous alginate foams. The new materials investigated in this study have remarkable thermal properties, including thermal conductivity lower than 0.041 W m^?1 K^?1 and low heat release (below 2 kJ g^?1), which allows labeling these foams self‐extinguishing materials. An experimental design methodology, based on a Box‐Behnken plan with three parameters and three levels, is successfully used for evaluating the impact of the amounts of alginate, SLS, and copper carbonate on the productivity, apparent density, and shrinking at air‐drying. It yielded an optimization of the process for the manufacturing of light, and stable/rigid insulating and thermally stable materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45868.