catena-Poly[[{bis­[tetra­aqua­(2-hy­droxy-3,4-dioxocyclo­but-1-en-1-olato-κO 1)bariumstrontium(0.35/0.65)]di-μ-aqua}­bis­(μ-2-hy­droxy-4-oxocyclo­but-1-ene-1,3-diolato-κ2 O 1:O 3)] monohydrate]

The title structure, {[Ba0.71Sr1.29(C4HO4)4(H2O)10]·H2O}n, is built from dimers of edge-sharing monocapped square anti­prisms [(Ba/Sr)O3(H2O)6], in which barium and strontium are statistically disordered [ratio 0.353 (8):0.647 (8)] on the same crystallographic site. Such dimers are connected via bidentate hydrogen squarate groups [HC4O4]−, leading to chains that propagate along the b axis. Inter- and intra­molecular O—H⋯O hydrogen bonds maintain the crystal packing through a three-dimensional network

Markov Models and Extensions for Land Cover Mapping in Aerial Imagery

International audienceMarkov models are well-established stochastic models for image analysis and processing since they allow one to take into account the contextual relationships between image pixels. In this paper, we attempt to methodically review the use of Markov models and their extensions for Land Cover mapping problem in aerial imagery according to available literature and previous research works. A new Markov model combining Markov random fields and hidden Markov models and inspired from the NSHP-HMM model, initially introduced for Handwritten Words Recognition is defined. New learning and labeling procedures are derived

(±)-Bis(1-carb­oxy-2-phenyl­ethanaminium) hexa­fluoro­silicate(VI)

The asymmetric unit of the title fluoro­silicate salt, 2C9H12NO2 +·SiF6 2−, consists of a phenylalaninium cation and half of a fluorosilicate anion, the Si atom being located on an inversion center. In the crystal, all of the F atoms act as hydrogen-bond acceptors and link the cations through different graph-set motifs, forming layers developing parallel to (100)

Poly[[μ-aqua-tetraaquabis(μ-2-hydroxy-4-oxocyclobut-1-ene-1,3-diolato)strontium] hemihydrate]

In the title coordination polymer, {[Sr(C4HO4)2(H2O)5]·0.5H2O}n, the Sr2+ ion is coordinated by three monodentate hydrogensquarate (hsq) anions and six aqua ligands in a distorted SrO9 monocapped square-anti­prismatic geometry. The hsq anions and water mol­ecules bridge the metal ions into infinite sheets lying parallel to (100). The O atom of the uncoordinated water mol­ecule lies on a crystallographic twofold axis. The packing is stabilized by numerous O—H⋯O hydrogen bonds

SYNTHESIS, STRUCTURAL CHARACTERIZATION AND PHOTOCATALYTIC ACTIVITY OF TIO2 NANOPARTICLES

Titanium dioxide (TiO2) nanoparticles were synthesized via sol-gel process (soft chemistry), using the metal alkoxide as precursor.  TiO2 is a promising material especially when it is reduced to the nanometric scale, but many parameters influence its nanoscale synthesis. In this work, the influence of calcination time was studied. The structure, morphology and size of the synthesized particles were determined by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The XRD diffractograms revealed an anatase structure of the as prepared TiO2, with a nanometric size. The average particle size of TiO2, synthesized in ethanol as a solvent, is estimated to be 17 nm. An increase of calcination time induced an increase of the particle size to 21 nm, while keeping the anatase phase unchanged. FTIR measurements confirmed the pure anatase phase of TiO2 and the SEM micrographs displayed the aggregation of the nanoscale particles. The photocatalytic activity of synthesized nanoparticles was investigated by degradation of  methylene blue dye by TiO2 nanoparticles under ultraviolet radiation

Combining Extended Dependency Tree –HMM based Recognition and Unsupervised Segmentation for Land Cover Mapping in Aerial Images

International audienceAn important challenge to any image pixels classification system is to correctly assign each pixel to its proper class without blurring edges delimiting neighboring regions. In this paper, we present an aerial image mapping approach that advantageously combines unsupervised segmentation with a supervised Markov model based recognition. The originality of the proposed system carries on three concepts: the introduction of an auto-adaptive circular-like window size while applying our stochastic classification to preserve region edges, the extension of the Dependency Tree –HMM to permit the computation of likelihood probability on windows of different shapes and sizes and a mechanism that checks the coherence of the indexing by integrating both segmentations results: from unsupervised over segmentation, regions are assigned to the predominating class with a focus on inner region pixels. To validate our approach, we achieved experiments on real world high resolution aerial images. The obtained results outperform those obtained by supervised classification alone

Extended Dependency Tree-HMM for Non-Rectangular Sub-Images Modeling

International audienceThis work is motivated by the need of evaluating the likelihood probability on sub-images of not necessarily rectangular shape in some frameworks. For this purpose, we propose an alternative of Dependency Tree- HMM that allows the four traditional interactions between neighboring pixels instead of just two. To demonstrate the accuracy of the proposed model, we provide some classification results performed on high resolution aerial images

Second-Order Belief Hidden Markov Models

Hidden Markov Models (HMMs) are learning methods for pattern recognition. The probabilistic HMMs have been one of the most used techniques based on the Bayesian model. First-order probabilistic HMMs were adapted to the theory of belief functions such that Bayesian probabilities were replaced with mass functions. In this paper, we present a second-order Hidden Markov Model using belief functions. Previous works in belief HMMs have been focused on the first-order HMMs. We extend them to the second-order model

Bis(cytosinium) aqua­penta­chlorido­indate(III)

The asymmetric unit of the title compound, (C4H6N3O)2[InCl5(H2O)], comprises two independent cytosinium cations and an aquapentachloridoindate anion. The InIII ion is in a slightly distorted octa­hedral coordination geometry. In the crystal, alternating layers of cations and anions are arranged along [010] and are linked via inter­molecular N—H⋯O, O—H⋯Cl and N—H⋯Cl hydrogen bonds, forming sheets parallel to (001). Additional stabilization within these sheeets is provided by weak inter­molecular C—H⋯O inter­actions

Tris(piperazine-1,4-diium) bis­[hexa­chloridoindate(III)] tetra­hydrate

The asymmetric unit of the title compound, (C4H12N2)3[InCl6]2·4H2O, consists of one and half independent piperazinium cations, an hexa­chloridoindate anion and two mol­ecules of water. The InIII ion is six-coordinated and forms a quasi-regular octa­hedral arrangement. In the crystal, alternating layers of cations and anions are arranged parallel to (10) and are linked with the water mol­ecules via intra- and inter­molecular N—H⋯O, O—H⋯Cl, C—H⋯O and N—H⋯Cl hydrogen bonds, forming a complex three-dimensional network. Additional stabilization within the layers is provided by weak inter­molecular C—H⋯Cl inter­actions