Search results for " split"
showing 10 items of 264 documents
Influence of annealing atmosphere on photoelectrochemical response of TiO2 nanotubes anodized under controlled hydrodynamic conditions
2021
[EN] The influence of three annealing atmospheres (air, nitrogen and argon) and the use of controlled hydrodynamic conditions (from 0 to 5000 rpm) on morphological, structural, chemical and photoelectrochemical properties of TiO2 nanotubes have been evaluated. For this purpose, different characterization techniques have been used: Field Emission Scanning Electron Microscopy, Raman Confocal Laser Spectroscopy, X-Ray Diffraction, X-Ray Photoelectron Spectroscopy, Incident Photon-to-electron Conversion Efficiency measurements, ultraviolet-visible absorption spectra, Mott-Schottky analysis and photoelectrochemical water splitting tests. According to the results, it can be concluded that both hy…
Current‐voltage curves of bipolar membranes
1992
Bipolar membranes consist of a layered ion‐exchange structure composed of a cation selective membrane joined to an anion selective membrane. They are analogous to semiconductor p‐n devices as both of them present current‐voltage curves exhibiting similar rectification properties. In this article, we present some current‐voltage curves obtained for different bipolar membranes at several temperatures. The results can be interpreted in terms of a simple model for ion transport and field‐enhanced water dissociation previously developed. The mechanism responsible for water splitting is assumed to be a catalytic proton transfer reaction between the charged groups and the water at the membrane int…
Operator splitting methods for American option pricing
2004
Abstract We propose operator splitting methods for solving the linear complementarity problems arising from the pricing of American options. The space discretization of the underlying Black-Scholes Scholes equation is done using a central finite-difference scheme. The time discretization as well as the operator splittings are based on the Crank-Nicolson method and the two-step backward differentiation formula. Numerical experiments show that the operator splitting methodology is much more efficient than the projected SOR, while the accuracy of both methods are similar.
On the modelling of an Acid/Base Flow Battery: An innovative electrical energy storage device based on pH and salinity gradients
2020
Abstract Electrical energy storage can enhance the efficiency in the use of fluctuating renewable sources, e.g. solar and wind energy. The Acid/Base Flow Battery is an innovative and sustainable process to store electrical energy in the form of pH and salinity gradients via electrodialytic reversible techniques. Two electromembrane processes are involved: Bipolar Membrane Electrodialysis during the charge phase and its opposite, Bipolar Membrane Reverse Electrodialysis, during the discharge phase. For the first time, the present work aims at predicting the performance of this energy storage device via the development of a dynamic mathematical model based on a multi-scale approach with distr…
Modeling and Performance Assessment of the Split-Pi Used as a Storage Converter in All the Possible DC Microgrid Scenarios. Part II: Simulation and E…
2021
Bidirectional DC/DC converters such as the Split-pi can be used to integrate an energy storage system (ESS) into a DC microgrid providing manifold benefits. However, this integration deserves careful design because the ESS converter must behave like a stiff voltage generator, a non-stiff voltage generator, or a current generator depending on the microgrid configuration. Part I of this work presented a comprehensive theoretical analysis of the Split-pi used as an ESS converter in all the possible DC microgrid scenarios. Five typical microgrid scenarios were identified. Each of them required a specific state-space model of the Split-pi and a suitable control scheme. The present paper complete…
Photocatalytic and photothermocatalytic applications of cerium oxide-based materials
2020
Abstract Cerium dioxide (CeO2) presents unique properties as the special electronic and optical properties of the 4f electrons, the capacity to form nonstoichiometric oxygen-deficient CeO2 − x oxides, the high oxygen mobility, and the reversible transformation between Ce4 + and Ce3 + that make it interesting for photocatalytic applications. CeO2 is a wide bandgap semiconductor (3.0–3.4 eV), but different approaches as combination with oxides, deposition of noble metals, doping with metal and nonmetal species, and the formation of surface defects have been adopted to extend its absorption towards the visible region with the aim to improve its photocatalytic performance. Cerium oxide-based ma…
A rare example of nickel(ii) chains based on a heteroscorpionate-like ligand with quadruple imidazolyl interactions
2014
The first nickel(ii) complex with the heteroscorpionate-like bridging ligand DIMMAL (2-di1H-2-imidazolylmethylmalonate), [Ni(DIMMAL)(H2O)3]n·3nH2O (1), is a one-dimensional coordination polymer whose structure shows regular Ni(ii) chains with H-bonding inter-chain interactions and a rare example of a Quadruple Imidazolyl Embrace (QIE). The Ni(ii) chain shows a weak antiferromagnetic interaction that can be modelled with a regular S = 1 chain model including a zero field splitting with g = 2.270, J = -1.5 cm(-1) and D = -2.26 cm(-1).
Preparation and structural studies on dibutyltin(IV) complexes with pyridine mono- and dicarboxylic acids
2004
Abstract A number of organotin(IV) complexes with pyridine mono- and dicarboxylic acids (containing ligating –COOH group(s) and aromatic {N} atoms) were prepared in the solid state. The bonding sites of the ligands were determined by means of FT-IR spectroscopic measurements. It was found that in most cases the –COO− groups form bridges between two central {Sn} atoms, thereby leading to polymeric (oligomeric) complexes. On this basis, the experimental 119Sn Mossbauer spectroscopic data were treated with partial quadrupole splitting approximations. The calculations predicted the existence of complexes with octahedral (oh) and trigonal-bipyramidal (tbp) structures, but the formation of comple…
Mössbauer spectroscopic studies on compounds containing tin-cadmium and tin-zinc bonds
1975
The Mossbauer parameters of compounds Ph3Sn MCl · TMED (M = Cd, Zn; TMED = N,N,N′,N′-tetramethylethylenediamine), (Ph3Sn)2CdL2 (L2 = TMED, 2,2′-bipyridine and o-phenanthroline) and (Ph3Sn)2 Zn · TMED have been determined and are discussed in connection with Mossbauer data concerning Ph3SnIV derivatives with other Sn-metal bonds. The isomer shift values suggest a high s character in SnCd and SnZn bonds resulting in deviations from regular tetrahedral environments around tin. Experimental quadrupole splittings and calculated partial quadrupole splitting values indicate reduced donor abilities towards the tin atom of an individual Ph3SnIV moiety by Cd-and Zn(Ph3Sn)1−nClnL2 (i.e., the remaini…
Purely Spectroscopic Determination of the Spin Hamiltonian Parameters in High-Spin Six-Coordinated Cobalt(II) Complexes with Large Zero-Field Splitti…
2019
Accurate determination of the spin Hamiltonian parameters in transition-metal complexes with large zero-field splitting (ZFS) is an actual challenge in studying magnetic and spectroscopic properties of high-spin transition metal complexes. Recent critical papers have convincingly shown that previous determinations of these parameters, based only on the magnetic data, have low accuracy and reliability. A combination of X-band electron paramagnetic resonance (EPR) spectroscopy and SQUID magnetometry seems to be a more convincing and accurate approach. However, even in this case, the accuracy of the determination of the spin Hamiltonian parameters is strongly limited. In this work, we propose …