Change detection in SAR time-series based on the coefficient of variation

This paper discusses change detection in SAR time-series. Firstly, several statistical properties of the coefficient of variation highlight its pertinence for change detection. Then several criteria are proposed. The coefficient of variation is suggested to detect any kind of change. Then other criteria based on ratios of coefficients of variations are proposed to detect long events such as construction test sites, or point-event such as vehicles. These detection methods are evaluated first on theoretical statistical simulations to determine the scenarios where they can deliver the best results. Then detection performance is assessed on real data for different types of scenes and sensors (Sentinel-1, UAVSAR). In particular, a quantitative evaluation is performed with a comparison of our solutions with state-of-the-art methods

Building profile reconstruction using TerraSAR-X data time-series and tomographic techniques

This work aims to show the potentialities of SAR Tomography (TomoSAR) techniques for the 3-D characterization (height, reflectivity, time stability) of built-up areas using data acquired by the satellite sensor TerraSAR-X. For this purpose 19 TerraSAR-X single-polarimetric multibaseline images acquired over Paris urban area have been processed applying classical nonparametric (Beamforming and Capon) and parametric (MUSIC) spectral estimation techniques

Low-bid Auction Versus High-bid Auction For Siting Noxious Facilities in a Two-city Region: an Exact Approach

Two auctions have been proposed in the literature for siting noxious facilities: the high-bid and the low-bid auctions. In this paper, we pursue the analysis of these auctions made by O'Sullivan [1993], where he concludes that the high-bid auction has the edge over the low-bid auction. We point out that O'Sullivan has made an approximation for the expected value of the compensation obtained with the high-bid auction, and we show how to obtain the exact value. We discuss a paradox linked with O'Sullivan's result, which mitigates his conclusions, and we show that with exact compensation, the high-bid auction mechanism is indeed far superior to the low-bid auction Deux enchères ont été proposées dans la littérature pour localiser les biens publics générateurs de nuisances : l’enchère à compensation haute et l’enchère à compensation basse. Dans ce papier, nous poursuivons l’analyse faite par O’Sullivan [1993] de ces deux enchères, dans laquelle il conclut que l’enchère à compensation haute domine l’enchère à compensation basse. Nous soulignons le fait que O’Sullivan a utilisé une approximation pour la valeur espérée de la compensation dans l’enchère à compensation haute et nous montrons comment obtenir la valeur exacte. Nous discutons d’un paradoxe, lié au résultat de O’Sullivan, qui nuance ses conclusions, et nous montrons qu’avec la compensation exacte l’enchère à compensation haute est largement supérieure à l’enchère à compensation bassenoxious facility siting, NIMBY syndrome, auction scheme, Nash equilibrium, low-bid auction, high-bid auction, biens publics générateurs de nuisances, localisation, syndrome NIMBY, enchères, équilibre de Nash, enchère à compensation basse, enchère à compensation haute

Impact of downstream processing on crystal quality during the precipitation of a pharmaceutical product

In pharmaceutical industries, active pharmaceutical ingredients (API) are made of crystals whose properties must be controlled because they influence the end-use properties of the drug. Even if crystal quality is mainly determined during the precipitation step, downstream processing also has an influence. In this study, the influence of washing on the crystal size and shape was analyzed. For the API being considered, different impurities have to be removed from the final suspension by filter cake washing. The efficiency of the washing steps was measured by different types of characterization on the solid phase (differential scanning calorimetry, scanning electron microscopy, and size distribution) and on the remaining filtrate (concentration of impurities). A second component also coprecipitates with the API. A specific study has been carried out on the withdrawal of this by-product and on its impact on the evolution of the crystalline form during washing steps. It was found that three filter cake washings allow us to remove all the impurities and to obtain a pure crystalline form

Influence of pH, Temperature and Impurities on the Solubility of an Active Pharmaceutical Ingredient (API)

Solubility, which defines the liquid /solid equilibrium, is a key parameter to control a crystallization process. This work is focused on the effects of pH, temperature and impurities on the aqueous solubility of an Active Pharmaceutical Ingredient (API).As the API is a weak acid (pKa = 3.7), its solubility increases with the pH. On the basis of the experimental curve of solubility, a model was defined to fit the evolution of the solubility as a function of pH. In the case of this compound, studies revealed a weak influence of the temperature in comparison with the pH. So, the solubility of the compound is slightly impacted by the temperature.Some experiments were carried out in order to compare the solubility of the API, at the same pH and temperature, for different concentrations of impurities found in the process. The results revealed a solubility increase in presence of acetic acid and a high solubility decrease in presence of sodium chloride. By carrying out experiments on common ions salts, the anion chloride Cl- has been identified as the cause of the solubility decrease

Characterization of the conglomerate form of acetyl-dl-leucine by thermal analysis and solubility measurements

Starting from a mixture of enantiomers in solution, crystallization can generate different types of crystals. In order to determine which type of crystal is obtained in the case of acetylleucine, an active pharmaceutical ingredient (API), analytical methods have been used to partially elucidate the binary and ternary phase diagrams of the system composed of the two enantiomers and water.The melting temperature phase diagram of this compound has been obtained by using differential scanning calorimetry (DSC) analyzes. The results show that it is characteristic of a conglomerate. This mode of crystallization has also been confirmed by X-ray powder diffraction analysis. Solubility measurements of enantiomerical mixtures in water enabled the determination of the ternary diagram of solubility. The empiric Meyerhoffer double solubility rule has been modified, due to the characterization of interactions between enantiomers

Role of Lewis acid sites of ZSM-5 zeolite on gaseous ozone abatement

In this work, chemical interactions between ozone and zeolite surface active sites are studied in order to propose a process for gaseous ozone removal. Synthetic ZSM-5 zeolites with three different Si/Al2 ratios and similar specific surface areas and microporous volumes were used in this study. Zeolite samples were characterised using Fourier Transform InfraRed spectroscopy (FTIR) and pyridine sorption IR studies in order to determine acidic site concentrations and strength. Ozone removal experiments were conducted in a quartz fixed-bed flow reactor, at 20°C and 101 kPa. Experiments using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) were conducted in order to identify adsorbed ozone and/or adsorbed oxygen species on zeolite surface. Pyridine IR measurements evidence two kinds of Lewis acid sites induced by extra-framework aluminium species and electronic aluminium defaults inside zeolite structure. Results obtained here evidence the important role of acidic surface sites of ZSM-5 zeolite on gaseous ozone removal. The total amount of removed ozone is found to be directly proportional to the total content of Lewis acid sites. DRIFTS experiments exhibit two bands around 800 and 1400 cm-1 that could correspond to adsorbed oxygen species linked to zeolite surface. DRIFTS experiments also exhibit a band around 1100 cm-1 that correspond to adsorbed ozone on the zeolite surface. Gaseous ozone removal using ZSM-5 zeolite could be largely attributed to ozone decomposition on Lewis acid sites and also to ozone adsorption on the surface of the zeolites

JEGA: a joint estimation and gossip averaging algorithm for sensor network applications

Distributed consensus algorithms are widely used in the area of sensor networks. Usually, they are designed to be extremely lightweight at the price of computation time. They rely on simple local interaction rules between neighbor nodes and are often used to perform the computation of spatial statistical parameters (average, variance, regression). In this paper, we consider the case of a parameter estimation from input data streams at each node. An average consensus algorithm is used to perform a spatial regularization of the parameter estimations. A two step procedure could be used: each node first estimates its own parameter, and then the network applies a spatial regularization step. It is however much more powerful to design a joint estimation/regularization process. Previous work has been done for solving this problem but under very restrictive hypotheses in terms of communication synchronicity, estimator choice and sampling rates. In this paper, we study a modified gossip averaging algorithm which fulfills the sensor networks requirements: simplicity, low memory/CPU usage and asynchronicity. By the same way, we prove that the intuitive idea of mass conservation principle for gossip averaging is stable and asympotically verified under feedback corrections even in presence of heavily corrupted and correlated measures