Safeguarded use of the implicit restarted lanczos technique for solving non-linear structural eigensystems

This paper presents a new algorithm for evaluating the eigenvalues and their corresponding eigenvectors for large-scale non-linear eigensystems in structural dynamics. The algorithm is based on solving a sequence of algebraic eigenproblems and updating the parameter λ. The implicitly restarted Lanczos method had been determined to be well suited for solving the linear eigenproblems that arise in this context. A zero-finder approach that uses rational interpolation to approximate the generalized eigenvalues has been developed to update λ. The methodology of the new algorithm developed here is designed to evaluate a subset of the parametrized non-linear eigencurves at specific values of λ. Numerical experiments show that the new eigensolution technique is superior to existing approaches for large-scale problems and competitive for small-size problems. The main emphasis of this contribution is the derivation and analysis of this scheme for non-linear structural eigensystems.     

Spatiotemporal evolution of the El Biar landslide (Algiers): new field observation data constrained by ground-penetrating radar investigations

Bulletin of Engineering Geology and the Environment - A better understanding of the spatiotemporal evolution of landslides in urban zones is a key factor in assessing the risk of future slides...     

Synthesis and physical properties of new oxide AgMnO<Subscript>2</Subscript>

A novel oxide AgMnO₂ was prepared from LiMnO₂ via Ag⁺ → Li⁺ exchange in the eutectic melt AgNO₃-KNO₃. It crystallizes in a monoclinically distorted unit cell (SG C2/m) caused by the Jahn-Teller (J-T) ion Mn³⁺ (3d ⁴). The structure was refined by isotypy with the crednerite CuMnO₂. There are two long axial Mn–O of 264.2(0) pm and four equatorial bonds of 192.7(3) pm and Mn–O–Mn adjoining (83.07°) are bent below the ideal angle. The thermal variation of the magnetic susceptibility (χ/T ⁻¹) obeys a Curie-Weiss law with manganese in a trivalent, high spin (HS) state accommodated in elongated MnO₆ octahedra (14.8%). Direct coupling between Mn³⁺ involves negative exchange interactions through long-range antiparallel moments with a temperature θ _p = −436 K and a magnetic moment of 5.26 μ_B/Mn³⁺ slightly larger than the spin only moment. The title oxide is stable in air up to ∼680 °C before it decomposes into metal silver. It displays a semi-conducting behavior with an activation energy of ∼0.45 eV, characteristic of a conduction by low mobility polarons between Ag^+/2+ where nearly all polarons are bonded. The photoelectrochemical properties of AgMnO₂ have been investigated by photocurrent technique in 1 M KOH. The cathodic photocurrent J _ph provides unambiguous evidence of p-type character attributed to oxygen insertion (0.025 oxygen by formula unit) as required by the charge compensating mechanism. The valence band is made up of Ag−4d wave functions positioned at ∼5.14 eV below vacuum. A comparison with CuMnO₂ was also reported.     

Reliable and Adaptive Distributed Public-Key Management Infrastructure for the Internet of Things

Wireless Personal Communications - The Internet of Things (IoT) is an emerging paradigm in the world of computer networks, where physical objects are connected over the Internet. Given the huge...     

Analytical modelling and experimental validation of proton exchange membrane electrolyser for hydrogen production

Proton Exchange Membrane (PEM) Electrolysers (ELSs) are considered as pollution-free with enhanced efficiency technology. Hydrogen can be easily produced from different resources like biomass, water electrolysis, natural gas, propane, and methanol. Hydrogen generation from water electrolysis, which is the splitting of water molecules into hydrogen and oxygen using electricity, can be beneficial when used in combination with variable Renewable Energy (RE) technologies such as solar and wind. When the electricity used for water electrolysis is produced by a variable RE source, the hydrogen stores the unused energy for a later use and can be considered as a renewable fuel and energy resource for the transport and energy sectors.This paper aims to propose a novel graphical model design for the PEM-ELS for hydrogen production based on the electrochemical, thermodynamical and thermal equations. The model under study is experimentally validated using a small-scale laboratory electrolyser. Simulation results, using Matlab-Simulink?, show an adequate parameter agreement with those found experimentally. Therefore, the impact of the different parameters on the electrolyser dynamic performance is introduced and the relevant analytical-experimental comparison is shown. The temperature effect on the PEM-ELS dynamic behaviour is also discussed.     

Corrosion behaviour of steel in the presence of Y(III) salts: Kinetic and mechanistic studies

The corrosion resistance of carbon steel after deposition of yttrium rich (hydr)oxide films on its surface was evaluated as a function of the Y(III) concentration in the solution, the immersion time and the presence of oxygen. During film formation in an aerated solution, two different cathodic reactions are involved: oxygen reduction and water reduction.The rate of oxygen reduction is lowered, whereas water reduction is activated in the presence of Y(III) in the solution. In the absence of oxygen, activated water reduction gets the main cathodic reaction, leading to polarization resistance values which are lower in the presence than in the absence of Y(III) ions.     

Revisiting aqueous alkaline silicates as precursors for sol-gel optical coatings

Alkaline silicates are well-known soluble silica derivatives already widely used for industrial purposes. Nevertheless, their applications for the elaboration of functional optical coatings have largely been discarded by the sol-gel community who mainly focused on alkoxide precursors. The objective of this work is to reconsider the alkaline silicates sol-gel chemistry, targeting optical coatings of a few hundreds of nanometers. The structures of Li⁺, Na⁺, and K⁺ silicate coatings are discussed on the basis of spectroscopic characterizations. We show that a simple washing process allows a postdeposition removal of most alkaline ions, thus preventing the efflorescence effect and improving the aqueous stability of the films. Finally, several examples are shown for the application of alkaline silicates in the elaboration of functional optical coatings following conventional sol-gel chemistry.     

Using technology to encourage a healthier lifestyle in people with Down’s syndrome

Universal Access in the Information Society - This article reports on the development of a mobile app developed to encourage healthier lifestyles, with emphasis on food intake, by people with...     

Synergistic or additive corrosion inhibition of mild steel by a mixture of HEDP and metasilicate at pH 7 and 11

Electrochemical measurements (steady‐state current‐voltage curves and AC impedance) were coupled with mass‐loss measurements, SEM examinations, and EDSX analyses to investigate the inhibition of corrosion of a carbon steel by a mixture of phosphonic acid HEDP (acid 1, hydroxyethylene, 1‐1 diphosphonic) and sodium metasilicate pentahydrate Na₂SiO₃. 5H₂O in an industrial hard water containing 3.10^?3 M Ca²⁺ ions. At pH 7, HEDP and Ca²⁺ act in a synergistic manner, by formation of a HEDP and calcium containing layer. Addition of silicate at this pH value, allows to reach an efficiency of 94% due to an additive inhibition effect. At pH 11, metasilicate, HEDP, and Ca²⁺ ions reinforce the passive layer in a synergistic way. The mixture (1.7 · 10^?5 M HEDP + 2.6 · 10^‐3 M SiO^2?₃) in the Ca²⁺ containing electrolyte is shown to be able to inhibit efficaciously the corrosion of iron at room temperature, considering uniform corrosion at pH 7 or pitting corrosion at pH 11.     

Simulation of hydrodynamic behaviour and mass transfer efficiency of reduced pressure distillation

A random packing hydrodynamic simulator is designed specially to carry out experiments under reduced pressures with a counter-current flow air/water system. The simulator results (air/water system) compared to those obtained in a real packed distillation column (benzylchloride/ ethylbenzene system) show a good agreement between hydrodynamic parameters like pressure drop, flooding flow rate, and total liquid hold-up. Empirical relationships derived from the simulator experimental results are proposed allowing the calculation of the pressure drop in a packed distillation column, operating in the pressure range between 10 kPa and atmospheric pressure. The influence of reduced pressure on the HETP in the distillation column and interfacial area in the simulator was also investigated.