Preparation and characterization of CeO2–TiO2 support for Ru catalysts: Application in CWAO of p-hydroxybenzoic acid

The catalytic wet air oxidation of aqueous solutions of p-hydroxybenzoic acid has been carried out over CeO₂–TiO₂ supported ruthenium catalysts (Ru/Ce–Ti) at 140 °C and 50 bar of air. High activity of ruthenium supported catalysts was observed. It was found that the decrease of the molar ratio Ce/Ti from 3 to 1/3, improves the activity of Ru catalysts. The activity of the samples decreases in the following order: Ru/Ce–Ti (1/3) > Ru/CeO₂ ≈ Ru/TiO₂ > Ru/TiO₂DT51. Characterization of samples was performed by means of N₂ adsorption–desorption, XRD, UV–visible, TPR, SEM and TEM.     

Study of the recrystallization process of AlMgSi alloys containing transition elements

The addition of small amounts of the transition elements such as Zr, Mn and Cr, which have a low solubility in the α-aluminium solid solution and thus form dispersoids, to AlMgSi alloys showed that these elements inhibit recrystallization when the alloys are pre-heated prior to deformation. The formation of coarse particles during casting is mainly due to the presence of Fe. This type of particles found, even, in solution treated samples. The particles, with a diameter exceeding 3 μm, accelerate the recrystallization as they provide good sites for nucleation of recrystallization. Precipitate free zones (PFZ's) developed around the coarse particles favour nucleation of recrystallization by subgrain growth. The presence of dispersoid particles is found to shift the recrystallization energy peak towards higher temperatures. Intermediate annealing before deformation allowed to achieve a high rate of deformation by cold rolling due to the removal of the solute from the matrix by the formation of the hardening phases. Optical and transmission electron microscopy, hardness measurements and differential scanning calorimetry (DSC) were used to study the kinetics of precipitation and recrystallization of the AlMgSi alloys.     

Adaptive MRAC-based direct torque control with SVM for sensorless induction motor using adaptive observer

This paper presents an improved direct torque control (DTC) method for induction motor (IM) drive. The main drawback of the conventional DTC is the use of hysteresis comparators which leads to high torque and flux ripples. The improvement in this paper includes using the space vector modulation to preserve a constant switching frequency and to reduce totally flux and torque ripples. Besides, the torque and stator flux regulation will be done based on model reference adaptive control (MRAC) strategy to ensure a robust control against external disturbance and less sensitivity from machine parameter variation unlike the conventional proportional-integral (PI) controllers. Furthermore, a design of an adaptive observer based on Lyapunov stability is presented for speed/flux and load torque estimation. The observer can improve the control performances and decrease the cost and increase reliability of the global control system by reducing the number of sensors. The proposed strategy will be examined under simulation tests using Matlab/Simulink and experimental implementation with real-time interface (RTI) based on dSpace 1104 board.     

Preparation of a new ceramic microfiltration membrane from mineral coal fly ash: Application to the treatment of the textile dying effluents

New microfiltration membranes from mineral coal fly-ash material are obtained using ceramic method. Paste from mineral coal fly ash (obtained by calcinations at 800 °C of non-grinded mineral coal) is extruded to elaborate a porous tubular configuration used as supports. The support heated at 1125 °C, shows an average pore diameter and porosity of about 4.5 μm and 51%, respectively. The properties in terms of mechanical and corrosion resistances are very interesting. The elaboration of the layer based on fly-ash powder (obtained by sintering at 700 °C of a finely grinded mineral coal) is performed by slip-casting method. The heating treatment at 800 °C leads to an average pore size of 0.25 μm. The water permeability determined of this membrane is 475 L/h m² bar. This membrane can be used for crossflow microfiltration. The application to the treatment of the dying effluents generated by the washing baths in the textile industry shows an important decrease of turbidity (inferior to 1 NTU), of chemical oxygen demand (COD) values (retention rate of about 75%) and a total color removal. The performances in term of permeate flux and efficiency were determined and compared to those obtained using a commercial alumina microfiltration membrane. Almost the same stabilised permeate flux was obtained (about 100 L h⁻¹ m⁻²). So, it seems that the prepared membrane is suitable for such wastewater treatment.     

Effect of Nickel Nitrate Concentration on the Size of Nickel Oxide Nanoparticles Bio-synthesized by Artemisia herba-alba Aqueous Leaves Extract and Improving Their Antioxidant Activities

Journal of Inorganic and Organometallic Polymers and Materials - This work aims to investigate the effect of nickel nitrate concentration on the size and antioxidant activity of nickel oxide...     

Analysis of two particular iterative learning control schemes in frequency and time domains

This paper deals with iterative learning control design for multiple-input multiple-output (MIMO), linear time-invariant (LTI) systems. Two particular ILC schemes are considered and analyzed in both frequency and time domains. Some remarks on the convergence, implementation, robustness with respect to disturbances and reinitialization errors, as well as positive realness issues related to both schemes are provided.