Dual role of the six-coordinated molybdenum and lead ions in novel of photochromic properties of the molybdenum–lead–borate glasses

Transparent glasses were prepared by conventional melting–quenching method in the xMoO₃·(100 ? x)[3B₂O₃·PbO] system where 0 ≤ x ≤ 15 mol%. By increasing the MoO₃ content up to 20 mol% the PbMoO₄ crystalline phase appears. These systems exhibit a photochromic effect which can be induced through laser exposures (λ = 633 nm) directly on the bulk sample. Structural investigations by FTIR spectroscopy show that the photosensitive effect is due to a reduction of Mo⁶⁺ to Mo⁴⁺ and/or Mo⁵⁺ promoted by the oxidation of Pb²⁺ and some structural changes of the borate network.     

Modeling,simulation and control a hydraulic servo system

Hydraulic actuators are widely used in industrial applications due to several advantages like large force and torque, high power to weight ratio, rapid and accurate response. In this paper a nonlinear model of a hydraulic servo system is developed by means of the associated differential equations and then simulated using Matlab techniques. The model describes the behavior of a servo system FESTO TP511 with MOOG-DDV633 servovalve and includes the nonlinearities of friction forces, valve dynamics, oil compressibility and load influence. The nonlinear model is used to design an optimal controller based on estimated state parameters through simulation. A digital control platform based on Atmel ATmega8535 microcontroller is used to compare the behavior of hydraulic system under PD and optimal control. The control platform was designed like an interface between PC and process: the control algorithm runs on PC and the digital platform assures amplifying, filtering and data communication functions. Both simulation and experimental results are provided to show the effectiveness of the proposed model and control method. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Optimal Design of 2 DOF Parallel Kinematics Machines

The aim of this paper is to show the usefulness of the multicriteria approach to optimize the Parallel Kinematic Machines (PKM). Variations of the kinematic performances index remain not constant throughout workspace. Aiming to deal at the same time with multiple criteria in optimal design of PKM, we have developed a Multi-Objective Genetic Algorithm (MOGA) using concepts of Pareto optimality and niching techniques. The obtained results have shown that the use of MOGA in such kind of optimization problem enhances the quality of the optimization outcome, providing a better and more realistic support for the decision maker. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

The local structure of gadolinium vanadate–tellurate glasses and glass ceramics: Te2V2O9 crystalline phase

Glasses in the system xGd₂O₃ · (100 − x)[0.7TeO₂ · 0.3V₂O₅] with 0 ≤ x ≤20 mol% have been prepared from melt quenching method. Influence of gadolinium ions on structural behavior in vanadate–tellurate glasses has been investigated using FTIR spectroscopy, X-ray diffraction (XRD), and magnetic susceptibility measurements. The structural changes have been analyzed with increasing rare earth concentration. The structural changes, as recognized by analyzing band shapes of XRD and FTIR spectra, revealed that Gd₂O₃ causes a higher extent of network polymerization as far as 20 mol%. The structure of the heat-treated glasses was found to consist mainly of the Te₂V₂O₉ crystalline phase. These vitreous systems were investigated by magnetic susceptibility measurements. From the paramagnetic susceptibility χ was calculated at different temperature and from the 1/χ(T) graph, the Curie temperature of the glass has been evaluated. Magnetic susceptibility data show the presence of small antiferromagnetic interactions between the Gd⁺³ ions.     

Multimodel control approach for electrohydraulic servo systems

The paper proposes a control design approach based on a multipoint linearization method for linear electro-hydraulic servo systems. The nonlinear model of servo system is linearized around of operational points and Matlab environment is used to adjust the points distribution based on an errors estimation. These models are used to design an optimal controller which online modifies the feedback control parameters. Simulation and experimental results are provided to show the effectiveness of approach. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Trans-ferulic acid valorization into stilbene derivatives via tandem decarboxylation/Heck coupling using Pd/Al-SBA-15 materials

Pd-containing Al-SBA-15 materials were prepared and characterized in view of their utilization in the two-step valorization of trans-ferulic acid into stilbenes via tandem decarboxylation/Mizoroki-Heck coupling. Materials were found to be highly active and selective in the proposed chemistries, with quantitative conversion to target products under mild reaction conditions (typically 100 °C, 3–6 h reaction). Relevant insights on catalyst deactivation via sintering (Pd nanoparticles agglomeration) were also observed for the synthesized materials.     

A Model Predictive Control Algorithm Applied To Non-Linear Processes

Model predictive control (MPC) is an optimization-based approach that has been successfully applied to a wide variety of control problems. In most of nonlinear strategies, the controllers are based on linear models with fixed parameters so that the vast body of linear control theory can be applied. Other solutions include the use of a nonlinear analytical model, combinations of linear empirical models, etc. This paper presents an MPC algorithm which uses on-line simulation and rule-based control. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Optimal design of a 2 DOF parallel robot

This paper is aimed at presenting a study on the optimization of the Biglide mini parallel robot, which comprises two-degree-of-freedom (DOF) mini parallel robots with constant struts. The robot workspace is characterized and the inverse kinematics equation is obtained. In the paper, design optimization is implemented with Genetic Algorithms (GA) for optimization considering transmission quality index and workspace. Here, intended to show the advantages of using the GA, we applied it to a multicriteria optimization problem of 2 DOF mini parallel robot. Genetic algorithms (GA) are so far generally the best and most robust kind of evolutionary algorithms. A GA has a number of advantages. It can quickly scan a vast solution set. Bad proposals do not affect the end solution negatively as they are simply discarded. The obtained results have shown that the use of GA in such kind of optimization problem enhances the quality of the optimization outcome, providing a better and more realistic support for the decision maker. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)