Robust SVM-direct torque control of induction motor based on sliding mode controller and sliding mode observer

This paper proposes a design of control and estimation strategy for induction motor based on the variable structure approach. It describes a coupling of sliding mode direct torque control (DTC) with sliding mode flux and speed observer. This algorithm uses direct torque control basics and the sliding mode approach. A robust electromagnetic torque and flux controllers are designed to overcome the conventional SVM-DTC drawbacks and to ensure fast response and full reference tracking with desired dynamic behavior and low ripple level. The sliding mode controller is used to generate reference voltages in stationary frame and give them to the controlled motor after modulation by a space vector modulation (SVM) inverter. The second aim of this paper is to design a sliding mode speed/flux observer which can improve the control performances by using a sensorless algorithm to get an accurate estimation, and consequently, increase the reliability of the system and decrease the cost of using sensors. The effectiveness of the whole composed control algorithm is investigated in different robustness tests with simulation using Matlab/Simulink and verified by real time experimental implementation based on dS pace 1104 board.     

Looking at calcimimetics impact on hypercalcemia of immobilization: hypotheses and a case study

For the treatment of secondary hyperparathyroidism (HPTH-II) in dialysis patients and hypercalcemia in patients with parathyroid carcinoma. Calcimimetics are a new class of drugs approved in the European Community and the United States by the Food and Drug Administration that were designed to suppress parathyroid hormone (PTH) levels with a simultaneous reduction in serum calcium and phosphorus levels, and calcium phosphorus product (Ca x P). Hypocalcemia is a frequent finding during the correction phase of the HPTH-II with calcimimetics. By contrast, the appearance of a hypercalcemia has yet to be described. In this paper, we report a case of severe hypercalcemia of immobilization in a 40-year-old hemodialyzed woman treated by cinacalcet HCl for a severe HPTH-II (PTH>1,000 pg/mL). A kidney transplantation recipient 1983 to 1995, she was diagnosed with Charcot-Marie Tooth disease in 1991. She had multiple orthopedic interventions for kidney-related osteoarticular problems probably favored by the kidney graft and the immunosuppressive treatment. While she was receiving the maximum dose of 180 mg/day of cinacalcet HCl and PTH at 443 pg/mL, she needed to be hospitalized for a right hip prothesis. Two weeks after the intervention she developed a symptomatic hypercalcemia of 3.57 mmol/L which was resistant to several measures including lowering the calcium concentration in the dialysate, withdrawing all vitamin D and calcium supplementation and the administration of calcitonin. Her serum calcium level was finally stabilized in the 2.37-2.95 mmol/L by administration of a single intravenous dose of pamidronate. This observation illustrates that the pharmacological activation of the parathyroid CaR and other putative CaR on bone cells by calcimimetics did not protect against the occurrence of hypercalcemia of immobilization favored by a severe HPTH-II in a hemodialysis patient.     

Electrochemical boron-doped diamond film microcells micromachined with femtosecond laser: application to the determination of water framework directive metals

Planar electrochemical microcells were micromachined in a microcrystalline boron-doped diamond (BDD) thin layer using a femtosecond laser. The electrochemical performances of the new laser-machined BDD microcell were assessed by differential pulse anodic stripping voltammetry (DPASV) determinations, at the nanomolar level, of the four heavy metal ions of the European Water Framework Directive (WFD): Cd(II), Ni(II), Pb(II), Hg(II). The results are compared with those of previously published BDD electrodes. The calculated detection limits are 0.4, 6.8, 5.5, and 2.3 nM, and the linearities go up to 35, 97, 48, and 5 nM for, respectively, Cd(II), Ni(II) Pb(II), and Hg(II). The detection limits meet with the environmental quality standard of the WFD for three of the four metals. It was shown that the four heavy metals could be detected simultaneously in the concentration ratio usually measured in sewage or runoff waters.     

Magnetron sputtered tungsten oxide films activated by dip-coated platinum for ppm-level hydrogen detection

Platinum-activated tungsten oxide (Pt-WO₃) films are prepared for hydrogen (H₂) sensing applications. In this study, WO₃ films were fabricated by reactive magnetron sputtering and Pt clusters were deposited on them by dip-coating. The microstructure, chemical composition and phase structure of Pt-WO₃ films were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction, respectively. It was observed that a reconditioning period is required after a rest period of the sensor for obtaining a stable signal. A thermal treatment at 450 °C for 24 h is proposed to solve this problem.     

On piecewise smoothness of conjugacy of class P circle homeomorphisms to diffeomorphisms and rotations

We give a characterization of piecewise C ¹ class P-homeomorphism f of the circle with irrational rotation number and finitely many break points which is piecewise C ¹ conjugate to a C ¹-diffeomorphism. The following properties are equivalent:

?(i)?f is conjugate to a C ¹-diffeomorphism of the circle by a piecewise C ¹-homeomorphism. (ii)?The product of jumps of f in the break points contained in a same orbit is trivial. (iii)?f is conjugate to a C ¹-diffeomorphism of the circle by a piecewise linear (PL)-homeomorphism or a piecewise quadratic homeomorphism.

For a PL-homeomorphism f having the property (ii): f is conjugate to a rotation either by a PL-homeomorphism or by a piecewise analytic homeomorphism.     

H2 sensors based on WO3 thin films activated by platinum nanoparticles synthesized by electroless process

Platinum (Pt) nanoparticles were successfully synthesized on tungsten oxide (WO₃) thin films by electroless process without any further post-treatment. The prepared Pt nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy and field-emission scanning electron microscopy. Gas sensors based on the Pt–WO₃ films were found to provide repeatable and significant responses to ppm-level H₂. The size of Pt nanoparticles increases with the deposition time and has improved the sensing characteristics of the sensors. The work in this paper paves a facile way to the fabrication of Pt nanoparticles on metal oxide surface at a low temperature (68 °C).     

Sol–Gel Assisted Preparation of Chromia–Silica Catalysts for Non-Oxidative Dehydrogenation of Propane

Preparation of continuous silica gel in the presence of dissolved Cr(NO₃)₃ leads to a hard high surface area (710 m²/g) microporous xerogel. Formation of the gel in the pore structure of mesoporous Pore-Expanded MCM-41 (PE-MCM-41) and macroporous commercial Cab–O–Sil silica results in retention of the mesoporous structure in the case of PE-MCM-41, and the formation of a powder with a broad pore size distribution in the case of Cab–O–Sil silica. Comparison of the catalytic activities in non-oxidative dehydrogenation of propane revealed a linear correlation of the initial conversion with the surface area for all three samples. The sample prepared from PE-MCM-41 through a sol–gel assisted procedure was the most active, particularly with respect to the catalysts prepared by simple wet impregnation with chromium nitrate.     

Synthesis of onion-like mesoporous silica from sodium silicate in the presence of α,ω-diamine surfactant

Mesoporous silicas with vesicular and onion-like morphologies were assembled through hydrogen-bonding pathway from sodium silicate as silica source and electrically neutral α,ω-diamine, Jeffamine D2000 surfactant (H₂NCH(CH₃)CH₂[OCH₂CH(CH₃)]₃₃NH₂) as template in aqueous media at different synthesis temperatures (25, 60 and 100 °C). Assembling the material at 100 °C afforded onion-like core shell mesoporous silica, while at relatively lower temperature, e.g. 25 and 60 °C, multilamellar vesicles were obtained. Mesoporous silica with onion-like morphology was also obtained by a two-step synthesis involving an aging period of 20 h at room temperature followed by a hydrothermal stage (1–12 h) at 100 °C. The heavily cross-linked (Q⁴/Q³ ratio of 4.43) onion-like mesophase silica exhibited high hydrothermal stability. The BET surface area, pore volume and KJS (Kruk-Jaroniec-Sayari) pore diameter of the onion-like mesoporous silica were found to be 464 m² g⁻¹, 1.16 m³ g⁻¹ and 7.2 nm, respectively.     

Regeneration of a solid waste from an edible oil refinery

This work presents a valorization of a solid waste originating from an edible oil refinery called spent bleaching earth (SBE). The SBE material is first impregnated with an ammonium chloride solution (3 M), then treated directly in furnace at 400 °C during an hour followed by a washing in the cold by HCl 1 M. To elucidate the changes in its crystalline structure, induced by the regeneration method, the obtained material (RSBE) is characterized by several physicochemical methods (X-ray diffraction, FTIR, thermal analysis, BET and SEM). The characterization results show that the heat treatment in furnace and the chemical treatment (decomposition of NH₄Cl) don’t affect the structure of montmorillonite of regenerated material (RSBE). The study of porous texture by the nitrogen adsorption technique at −196 °C shows that the specific surface area S_BET and the pore volume increased in the RSBE material compared to those of virgin bleaching earth VBE (unused) and their values are respectively of 145.68 against 115.5 m² g⁻¹ and of 0.287 against 0.234 cm³ g⁻¹. Calculations by the adsorption equations using BJH method, applied to both materials, show that the treatment generate an increase in the micropores in the RSBE material. We belonged the values of the micropores area of S_mic = 41.98 cm² g⁻¹ and of V_mic = 0.074 cm³ g⁻¹ for the volume.     

Rhodium Complexed C2‐PAMAM Dendrimers Supported on Large Pore Davisil Silica as Catalysts for the Hydroformylation of Olefins

Polyamidoamine (PAMAM) dendrimers up to the third generation were grown for the first time on the surface of a large‐pore (18 nm) Davisil silica support. The supported dendrimers of generations 0, 1, 2 and 3 were phosphinomethylated and complexed with rhodium. All the generations were found to be very active for the hydroformylation of olefins. The hydroformylation of 1‐octene was accomplished with a turnover frequency of 1700 h⁻¹ at 70 °C. The G(1) material was found to be the most active when the different generations were compared at 50% conversion at 70 °C