Robust H∞ control for linear Markovian jump systems with unknown nonlinearities

This paper studies the problem of stochastic stability and disturbance attenuation for a class of linear continuous-time uncertain systems with Markovian jumping parameters. The uncertainties are assumed to be nonlinear and state, control and external disturbance dependent. A sufficient condition is provided to solve the above problem. An H_∞ controller is designed such that the resulting closed-loop system is stochastically stable and has a disturbance attenuation γ for all admissible uncertainties. It is shown that the control law is in terms of the solutions of a set of coupled Riccati inequalities. A numerical example is included to demonstrate the potential of the proposed technique.     

Characterization of an Algerian diatomite by inverse gas chromatography: Specific and non-specific contribution and Lewis acid–base parameters

The fundamental understanding of the behavior of a solid is intimately related to the understanding of the interactions on the surface of the latter, a major challenge in particular if the material is natural and ecological. The infinite dilution-inverse gas chromatography was used to evaluate the surface thermodynamic properties of several phases (grafted and/or coated) diatomite. A series of non- or polar-solute probes were injected at temperatures of 45?°C and 90?°C. The dispersive surface free energies values of the supports decrease with increasing temperature and their active surface is amphoteric with predominantly acidic character.     

Enhanced photocatalytic performance of CuAl2O4 nanoparticles spinel for dye degradation under visible light

Research on Chemical Intermediates - Environmental problems on a global scale have become more prominent with the population growth. For the removal of organic contaminants, the solar energy and...     

Target-level criterion in Markov decision processes

The Markov decision process is studied under the maximization of the probability that total discounted rewards exceed a target level. We focus on and study the dynamic programing equations of the model. We give various properties of the optimal return operator and, for the infinite planning-horizon model, we characterize the optimal value function as a maximal fixed point of the previous operator. Various turnpike results relating the finite and infinite-horizon models are also given.     

Effect of pH on Electrocoagulation of Bentonite Suspensions in Batch Using Iron Electrodes

The electrocoagulation of a synthetic wastewater has been studied in this work. The electrochemical process was carried out in a batch electrochemical cell equipped with iron electrodes without agitation. Bentonite suspensions were used as a model of wastes polluted with colloids, as clays behave as hydrophobic colloids in water. The results obtained were useful to clarify the mechanisms that are involved in the electrocoagulation of this kind of waste and also to study the influence of pH in the process. Two primary coagulation mechanisms can explain the experimental behavior of the system: at acid pH the neutralization of the superficial charges of the clays and at alkaline pH the enmeshment of the kaolin particles into a sweep floc. At neutral pH, the formed cations (Fe²⁺ and Fe³⁺) neutralize colloidal particles and conduct to the hydroxides (Fe(OH)_2(s) and Fe(OH)_3(s)) which adsorbate colloids and enhance sweep flocculation.     

Structure and intercalation behavior of copper II on the layered sodium silicate magadiite material

In this work, the ion-exchange reaction of the sodium silicate Na-magadiite with cupric ions was studied and the mode of interaction of the intercalated Cu²⁺ ions with silicate sheet was investigated. To do this, Na-magadiite was first synthesized using a hydrothermal method and characterized. It is then used to prepare Cu-exchanged magadiite materials with different copper contents by an ion-exchange reaction. The solids obtained were characterized by chemical and thermogravimetric analyses, powder X-ray diffraction, UV–Visible diffuse reflectance and Fourier transform spectroscopy, scanning electron microscopy and transmission electron microscopy. The results show that magadiite has a high affinity to copper ions and that the experimental exchange rate can be easily predicted. They show also that the intercalated Cu²⁺ ions are non-hydrated and are in direct interactions with the terminal interlayer ≡Si–O^? groups, to which they are also probably strongly linked. Furthermore, the interlayer copper oxide species phase formed are in form of small particles homogeneously dispersed. Finally, the introduction of Cu²⁺ ions into the interlayer space does not substantially affect the structure of the Cu-exchanged materials but rather tends to stabilize it by increasing the decomposition temperature of the silanol groups .