Investigation and control of magneto–rheological fluid dampers

A semi-active controllable fluid damper is described and studied in this paper. The damper employs magneto–rheological fluid that changes its properties in the presence of a magnetic field. This results in a damper whose characteristics may by adapted in real time to the user's requirements. Such dampers can be used to eliminate oscillations in different servo drive machine tools systems. In this paper a simulation model of those dampers is proposed and some control analyses are made. Construction of such a damper is described and finally experimental results of its performance are presented.     

Water vapour permeability,thermal and wetting properties of whey protein isolate based edible films

This study deals with the effect of whey protein isolate (WPI) and glycerol (GLY) used as a plasticizer on some physical properties of cast whey protein isolate (WPI) films. Films were prepared from heated (80 °C for 30 min) aqueous solutions of WPI at 7, 8, 9 and 10% (w/w), GLY (40%, w/w, of WPI) and WPI at 8% (w/w), GLY (30, 40, and 60%, w/w, of WPI). For all types of films, water vapour permeability for four relative humidity differentials (30–100%, 30–84%, 30–75%, and 30–53%), surface and thermal properties were measured. Varying the proportion of WPI and GLY in edible films had some effect on water vapour permeability, wetting and thermal properties of WPI films. A cumulative effect of both glycerol and protein content was observed on the water vapour permeability increase. Indeed film barrier properties are much better for the lowest WPI (7%) and GLY (40%) contents. GLY increases the degradation temperature and favours film surface wettability whereas protein content did not affects thermal properties of films.     

On Partially Entanglement Breaking Channels

Using well known duality between quantum maps and states of composite systems we introduce the notion of Schmidt number for a quantum channel. It enables one to define classes of quantum channels which partially break quantum entanglement.These classes generalize the well known class of entanglement breaking channels.     

Oxovanadium(IV) Schiff base complexes derived from 2,2′-dimethylpropandiamine: A homogeneous catalyst for cyclooctene and styrene oxidation

Tetradentate Schiff base ligands, derived from aromatic aldehydes and aliphatic diamine (2,2′-dimethylpropandiamine), and their vanadyl complexes have been prepared and characterized. Catalytic potential of these complexes was tested for the oxidation of cyclooctene and styrene using tert-butylhydroperoxide (TBHP) as oxidant. The effects of molar ratio of oxidant to substrate, temperature and solvent have been studied. Excellent selectivity of epoxidation for cyclooctene and good selectivity for styrene were obtained. The mechanism of oxidation has also been discussed.     

Improvement of electro-physical properties of ultra-thin PECVD silicon oxynitride layers by high-temperature annealing

Ultra-thin (5 and 6 nm) silicon oxynitride layers have been fabricated by the plasma-enhanced chemical vapour deposition (PECVD) process. Split experiments with annealing of the deposited dielectric layers were performed using the RTP reactor and a standard furnace, both at 900 °C. Possible changes in properties, structure and chemical composition of the obtained layers were investigated by means of spectroscopic ellipsometry, X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS) and electrical characterisation of manufactured test structures (metal-insulator-semiconductor (MIS) capacitors and MISFETs). The results achieved have shown that annealing at high temperature causes improvement of the properties of ultra-thin silicon oxynitride layers (e.g. lower interface traps density, lower leakage currents within the dielectric layer and lower charge-pumping currents of the MISFETs). The observed improvement in electro-physical properties can be attributed to the increase of the SiON phase. Moreover, comparison between the physical thickness and the equivalent oxide thickness (EOT) of the layers shows a decrease in physical thickness obtained by using the silicon oxynitride layer instead of the classical silicon dioxide. These findings are important for the consideration of chances of PECVD oxynitride layer application for CMOS technology.     

Monitoring of power dissipated in microelectronic structures

A method for monitoring of power dissipated in microelectronic structures is presented in the paper. The method can be applied to active cooling of packaged integrated circuits and can be used for fault diagnosis in VLSI systems. It is presented how the method is implemented as an application specific integrated circuit cell, followed by results of simulations and measurements after fabrication. The paper presents the principle and theoretical considerations of the mean value power monitoring in VLSI systems necessary for proper driving of the active heat sink.     

Experimental and DFT studies of N2O decomposition over bare and Co-doped magnesium oxide—insights into the role of active sites topology in dry and wet conditions

Isothermal and TPSR studies of deN₂O reaction were performed over model MgO, and Co–MgO systems. Complementary experiments such as O₂-TPD, H₂O-TPD and IR, supported by DFT molecular modeling were carried out to elucidate the role of topological irregularities such as corners, steps, edges on the principal reaction events in dry and wet environment. The hydroxyl groups produced upon water adsorption were used for selective blocking of the active sites. Topological aspect of the surface reactivity was discussed in terms of the energetics of reaction steps and the relative stability and mobility of reaction intermediates (O₂²⁻) and inhibiting (OH⁻_surf) species. Whereas the most active corner sites are depleted by oxygen, produced in the course of N₂O decomposition, the edge and step sites could be eliminated only by more strongly adsorbed water. In steady state conditions the reaction turns over mainly on terrace sites and is moisture insensitive. Upon introduction of Co²⁺ ions to magnesium oxide the N₂O conversion curve is shifted by 200 °C towards lower temperatures, due to the change in the N₂O activation step (from anionic redox to cationic redox). However, at such thermal conditions the terrace sites remain still hydroxylated, and the overall reaction rate is clearly deteriorated by water present in the feed.     

Flexible Independent Component Analysis

This paper addresses an independent component analysis (ICA) learning algorithm with flexible nonlinearity, so named as flexible ICA, that is able to separate instantaneous mixtures of sub- and super-Gaussian source signals. In the framework of natural Riemannian gradient, we employ the parameterized generalized Gaussian density model for hypothesized source distributions. The nonlinear function in the flexible ICA algorithm is controlled by the Gaussian exponent according to the estimated kurtosis of demixing filter output. Computer simulation results and performance comparison with existing methods are presented.     

LTCC compatible PLZT thick-films for piezoelectric devices

The production of PLZT thick-films for piezoelectric devices prepared from perovskite-type (Pb, La)(Zr, Ti)O₃ powders is described. The powder manufacture, paste preparation and thick-film production compatible with the low temperature co-fired ceramics (LTCC) process are detailed. The maximum firing temperature of applied technology is 850 °C. Measurements of the dielectric and piezoelectric properties of the produced films are carried out. The low dielectric loss (0.022) and high d₃₃ and d₃₁ piezoelectric coefficients (85.7×10⁻¹² and −34.6×10⁻¹² m/V, respectively) of the material, together with a relatively low sintering temperature, make it suitable for various applications, e.g. ultrasonics.