New time-varying fuzzy sets based on a PSO midpoint of the universe of discourse

The paper presents a robust parallel distributed compensation(PDC) fuzzy controller for a nonlinear and certain system in continuous time described by the Takagi-Sugeno(T-S) fuzzy model. This controller is based on a new type of time-varying fuzzy sets(TVFS). These fuzzy sets are characterized by displacement of the kernels to the right or left of the universe of discourse, and they are directed by a well-defined criterion. In this work, we only focused on the movement of midpoint of the universe. The movements of this midpoint are optimized by particle swarm optimization(PSO) approach.     

Elaboration of the hydroxyapatite with different precursors and application for the retention of the lead

Carbonate hydroxyapatite (CHAP) was synthesized from different precursors; synthetic (CaCO3 and Ca(OH)2) and natural (egg shell before and after calcinations at 900 degrees C) under different conditions and characterized by using TG/DTG analysis, X-ray powder diffraction (XRD) method and Fourier transform infrared (FT-IR) spectroscopy techniques. The results of these analyses indicate that the four powders present the same structure of hydroxyapatite. Furthermore the four powders obtained were used for the retention of lead. The results obtained indicated that all powders present high adsorption capacity for lead, but from environmental and economic views, the hydroxyapatite synthesized from eggshell no calcined (HA2) is most advantageous. The influence of different sorption parameters, such as: initial metal concentration, equilibration time, solution pH and sorbent dosage was studied and discussed.     

Antifungal activity of films and solutions based on chitosan against typical seed fungi

The use of eco-freindly polymers as antimicrobial materials is in growth due to the need to reduce the negative impact of conventional treatments on the environment and the human health. The purpose of the present study was to assess the antifungal properties of films and solutions based on chitosan with different molecular weight at different concentrations. Surfactants were added to the formulation to assess their impact on treatment efficiency. The antifungal activity was conducted against tree fungi, Aspergillus niger, Alternaria alternata and Rhizopus oryzae. Results indicated important and significant differences of the antifungal activity between chitosan based solutions and chitosan based films. Furthermore, the antifungal activity of the different treatment depended on the type of fungus treated. Thus, chitosan film treatments were significantly more effective on A. niger than solution treatments. On the other hand, solution treatments resulted in higher radial inhibition when applied against A. alternata or R. oryzae. The highest radial inhibition was observed against A. alternata (97%) using a chitosan solution. The influence of the other parameters (concentration, molecular weight and surfactant type) on treatment efficiency was not as important and their significance depended on treatment type and fungus nature.     

Inverse gas chromatography, surface properties, and interactions among components of paint formulations

Inverse gas chromatography (IGC) was applied to the surface characterization of polymers and pigments used in the formulation of protective coatings. IGC measurements over a significant temperature range provided surface energy and acid-base interaction parameters for these materials. Two sets of IGC data were obtained: (1) the quantity of vapor used to probe solid surfaces was extremely small, with results describing the properties of the most energetic surface sites; and (2) finite concentrations of vapor probes were used, with results describing the average properties of surface sites. A comparison of the two sets gave information on the heterogeneity of sites on the polymer and pigment surfaces. Heterogeneity parameters were defined for sites interacting through dispersion forces as well as for those able to interact as acids and bases. The present work reinforces the usefulness of surface characterizations by IGC by showing that the stability of pigments dispersed in the polymer vehicles was a function of the acid-base interaction between polymer-pigment pairs. Dept. of Chemical Engineering, Ecole Polytechnique, P.O. Box 6079, Stn. Centre Ville, Montreal, Que. H3C 3A7, Canada. 19-17 Ikeda Nakamachi, Neyagawa, Osaka 572, Japan.     

Transformation of the quasicrystalline phase Al-Cr-Fe induced by rapid solidification

A quasicrystalline phase, Q, with icosahedral symmetry was detected by X-ray diffraction and transmission electron microscopy in Al-3Cr-xFe (x=0 1 or 3 at %) alloys elaborated by hot extrusion of rapidly solidified powders. Chemical microanalysis showed the average composition of this phase to be 75 ± 0.5% Al, 12 ± 1%Cr, 12 ± 1% Fe. Annealing treatments led to its transformation into the equilibrium phases Al₁₃Cr₂ and Al₁₃Fe₄, directly at high temperature, or through a metastable and unknown phase, X, at intermediate temperature. This transformation was followed by X-ray diffraction, calorimetry and in situ electron microscopy. The convergent-beam technique was used for characterization of the X phase.     

Effect of Drying Conditions on the Mechanical and Barrier Properties of Films Based on Chitosan

Films plasticized with glycerine were prepared using chitosan with two different molecular weights (Mw), 780 and 430 kDa. Films were obtained by drying at 80 and 40°C at 20 and 40% relative humidity (RH) in a climatic chamber. Drying kinetics were established by the measurement of the evolution of the actual temperatures of the film forming solutions. Chitosan Mw did not show any significant influence on drying kinetics. Drying temperature affected drying kinetics in a more intense way than drying RH. Maximum tensile strength (86 MPa) and elongation at break (56.5%) were obtained with slow drying cycles (lower drying T) and when higher Mw chitosan was employed. Minimum water vapor permeability (0.59 g · mm/kPa · h · m) was achieved for films dried at faster drying cycles (higher drying T). Chitosan Mw was not a significant factor affecting water vapor permeability.     

A novel CMOS charge-pump circuit with current mode control 110 mA at 2.7 V for telecommunication systems

This paper presents a novel organization of switch capacitor charge pump circuits based on voltage doubler structures. Each voltage doubler takes a dc input and outputs a doubled dc voltage. By cascading voltage doublers the output voltage increases up to 2 times. A two-phase voltage doubler and a multiphase voltage doubler structures are discussed and design considerations are presented. A simulator working in the Q-V realm was used for simplified circuit level simulation. In order to evaluate the power delivered by a charge pump, a resistive load is attached to the output of the charge pump and an equivalent capacitance is evaluated. To avoid the short circuit during switching, a clock pairs generator is used to achieve multi-phase non-overlapping clock pairs. This paper also identifies optimum loading conditions for different configurations of the charge pumps. The proposed charge-pump circuit is designed and simulated by spice with TSMC 0.35-μm CMOS technology and operates with a 2.7 V to 3.6 V supply voltage. It has an area of 0.4 mm2; it was designed with a frequency regulation of 1 MHz and internal current mode to reduce power consumption.     

High electric tunability on oxynitride perovskite LaTiO2N thin films

Oxynitride LaTiO₂N thin films were deposited on Pt/Ti/SiO₂/Si substrates by RF reactive sputtering. X-ray diffraction analysis highlighted the polycrystalline structure of the films, while SEM showed regular, ordered grains with smooth surface. Our films gave interesting values of electric tunability compared to oxide films, especially the thinner one with an exceptional value of 72% obtained under a low voltage of only 3.3 V.     

Factorial design analysis for sorption of zinc on hydroxyapatite

A factorial design was employed to evaluate the quantitative removal of zinc from aqueous solutions on synthesized hydroxyapatite. The experimental factors and their respective levels studied were the initial zinc concentration in solution (35≤C(Zn)≤85 mg/L), adsorbent dosage (4.5≤C(susp)≤9.5 g/L), Ca/P molar ratio (1.667≤Ca/P≤2) and calcination temperature of hydroxyapatite (600≤T(Cal)≤800 °C). The adsorption parameters were analysed statistically by means of variance analysis by using the STATISTICA software. The experimental results and statistical analysis show that increasing in the calcination temperature from 600 to 800 °C decrease the zinc adsorption whereas the increase of adsorbent dosage increases it. Based on the analysis of variance and the factorial design of experiments, adsorbent dosage has a positive effect on the removal of zinc, whereas zinc concentration, Ca/P molar ratio and calcination temperature have a negative effect on this process. The factorial results also demonstrate the existence of statistically significant binary interactions of the experimental factors. The experimental results were fitted to the Langmuir and Freundlich equations to find out adsorption capacities. In most cases, the results indicate that the sorption data fits well in the Freundlich isotherm model. The results of XRD analysis, pH(PZC) and pH(Final) values indicated that ion exchange and dissolution/precipitation mechanisms predominate for the sorption of zinc on our hydroxyapatite.