Cobos M.,University of Valencia |
Perez-Solano J.J.,University of Valencia |
Belmonte O.,University JaumeI |
Ramos G.,Polytechnic University of Valencia |
Torres A.M.,University of Castilla - La Mancha
IEEE Transactions on Signal Processing | Year: 2016
Automatic ranging and self-positioning is a very desirable property in wireless acoustic sensor networks, where nodes have at least one microphone and one loudspeaker. However, due to environmental noise, interference, and multipath effects, audio-based ranging is a challenging task. This paper presents a fast ranging and positioning strategy that makes use of the correlation properties of pseudonoise sequences for estimating simultaneously relative time-of-arrivals from multiple acoustic nodes. To this end, a proper test signal design adapted to the acoustic node transducers is proposed. In addition, a novel self-interference reduction method and a peak matching algorithm are introduced, allowing for increased accuracy in indoor environments. Synchronization issues are removed by following a BeepBeep strategy, providing range estimates that are converted to absolute node positions by means of multidimensional scaling. The proposed approach is evaluated both with simulated and real experiments under different acoustical conditions. The results using a real network of smartphones and laptops confirm the validity of the proposed approach, reaching an average ranging accuracy below 1 cm. © 1991-2012 IEEE.
Artetxe B.,University of the Basque Country |
Reinoso S.,University of the Basque Country |
SanFelices L.,University of the Basque Country |
Gutierrez-Zorrilla J.M.,University of the Basque Country |
And 4 more authors.
Chemistry - A European Journal | Year: 2015
Reaction of early lanthanides, GeO2, and Na2WO4 in a NaOAc buffer results in large crown-shaped polyoxometalates based on [Ln2GeW10O38]6- subunits. By using Ni2+ as a crystallizing agent, [Na⊂Ln12Ge6W60O228(H2O)24]35- (Na⊂Ln12) hexamers formed by alternating β(1,5)/β(1,8) subunits were obtained for Ln=Pr, Nd. The addition of K+ led to a similar anion for Ln=Sm, namely, [K⊂Sm12Ge6W60O228(H2O)22]35- (K⊂Sm12) and [K⊂K7Ln24Ge12W120O444(OH)12(H2O)64]52- (K⊂Ln24) dodecamers that consist of a central core identical to K⊂Sm12 decorated with six external γ(3,4) subunits for Ln=Pr, Nd. These anions dissociate in water into hexameric cores and monomeric entities, as shown by ESI mass spectrometry. The former self-assemble into spherical, hollow, and single-layered blackberry-type structures with radii of approximately 75nm, as monitored by laser light scattering (LLS) and TEM techniques. Analogous studies performed for K⊂Nd24 in water/acetone mixtures show that the dodecamers remain stable and form in turn their own type of blackberries with sizes that increase from approximately 20 to 50nm with increasing acetone content. This control over both the composition and size of the vesicle-like assemblies is achieved for the first time by modifying the architecture of the species that undergoes supramolecular association through the solvent polarity. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Pedrajas E.,University JaumeI |
Sorribes I.,University JaumeI |
Sorribes I.,Leibniz Institute for Catalysis at the University of Rostock |
Junge K.,Leibniz Institute for Catalysis at the University of Rostock |
And 2 more authors.
ChemCatChem | Year: 2015
Herein, we report a novel well-defined diamino Mo3S4-based catalyst system for the reduction of nitroarenes and azo compounds to the corresponding anilines with silanes as reducing agents. This catalytic protocol provides a facile route to access aromatic amines under mild conditions in good to excellent yields. Notably, even anilines functionalized with other potentially reducible moieties are obtained with high selectivity. The new chemoselective catalyst of formula [Mo3S4Cl3(dmen)3](BF4) (dmen: N,N′-dimethylethylenediamine) is conveniently synthesized through coordination of the diamine ligand to the incomplete Mo3S4 cubane-type cluster core in a one-pot two-step procedure. The crystal structure of the [Mo3S4Cl3(dmen)3]+ cation confirms the formation of a single isomer in which the chlorine atom lies trans to the bridging sulfur atom to afford a C3 symmetry complex with intrinsic backbone chirality. The structure is preserved in solution, as evidenced by multinuclear NMR spectroscopy and electrospray-ionization mass spectrometric techniques. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Mohammadzadeh M.,Tarbiat Modares University |
Omidi M.,Ham University |
Mateu J.,University Jaumei
Proceedings of IAMG 2015 - 17th Annual Conference of the International Association for Mathematical Geosciences | Year: 2015
Statistical analysis of natural phenomena with spatial and temporal correlations requires specification of correlation structure via a covariance function. A separable spatio-Temporal covariance function is usually used for the ease of application. However, the separability property of the spatio-Temporal covariance function can be unrealistic in many settings. Although Gneiting (2002) proposed a general clab of non-separable spatio-Temporal covariance models but Kent et al. (2011) proved that some of Gneiting's models pobeb a counterintuitive dimple. We use a copula function to construct a new family of valid spatio-Temporal covariance functions with no dimple. Next, Bees Algorithm is applied to explore the spatio-Temporal correlation structure of monthly temperature data provided by the Illinois Climate Network.
Reeves-McLaren N.,University of Sheffield |
Sharp J.,University of Sheffield |
Beltran-Mir H.,University of Sheffield |
Rainforth W.M.,University JaumeI |
West A.R.,University JaumeI
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2016
The transformation on heating LiCoMnO4, with a spinel structure, to LiCoMnO3, with a cationdisordered rock salt structure, accompanied by loss of 25% of the oxygen, has been followed using a combination of diffraction, microscopy and spectroscopy techniques. The transformation does not proceed by a topotactic mechanism, even though the spinel and rock salt phases have a similar, cubic close-packed oxygen sublattice. Instead, the transformation passes through two stages involving, first, precipitation of Li2MnO3, leaving behind a Li-deficient, Co-rich non-stoichiometric spinel and, second, rehomogenization of the two-phase assemblage, accompanied by additional oxygen loss, to give the homogeneous rock salt final product; a combination of electron energy loss spectroscopy and X-ray absorption near edge structure analyses showed oxidation states of Co2+ and Mn3+ in LiCoMnO3. Subsolidus phase diagram determination of the Li2O-CoOx-MnOy system has established the compositional extent of spinel solid solutions at approximately 500 C. ©2016 The Authors.