Approximation of the controls for the linear beam equation

This article deals with the approximation of the boundary controls of a 1-D linear equation modeling the transversal vibrations of a hinged beam using a finite-difference space semi-discrete scheme. Due to the high frequency numerical spurious oscillations, the semi-discrete model is not uniformly controllable with respect to the mesh size and the convergence of the approximate controls corresponding to initial data in the finite energy space cannot be guaranteed. In this paper we analyze how do the initial data to be controlled and their discretization affect the result of the approximation process. We prove that the convergence of the scheme is ensured if the continuous initial data are sufficiently regular or if the highest frequencies of their discretization have been filtered out. In both cases, the minimal weighted \(L^2\)-norm discrete controls are shown to be convergent to the corresponding continuous one when the mesh size tends to zero.     

Capacitor-less A-RAM SOI memory: Principles, scaling and expected performance

Based on numerical TCAD simulations, the novel capacitor-less A-RAM memory cell is detailed in terms of electrostatic effects, transient operation and retention time. The particular double-body device architecture on SOI is beneficial for better scalability than conventional 1T-DRAMs. Its dual body partitioning suppresses the supercoupling effect in SOI; the two types of carriers can coexist inside ultrathin fully depleted transistors. Electrons and holes are accommodated in different bodies, separated by an insulator layer, but remain electrostatically coupled. A-RAM features easy discrimination of ‘0’ and ‘1’ states, simple control waveforms and very promising performance.     

Internal energy flow analysis within a single effect sorption heat pump

The knowledge of the characteristics of unused, excess and untapped exergy allows a thorough analysis of internal energy flows distribution within a sorption heat pump. It can be applied to any system based on gas–liquid absorption, adsorption or solid–gas reaction as well as to any process based on the internal recycling of the energy flux. It can also be applied for the case of a simple effect ideal machine, in particular in the definition of processes where the COP is larger than 2: the levels at which the initial exergy is downgraded on the one hand, as well as, the upgraded excess exergy produced on the other allows the designer to make a judicious choice of a system.     

Catalytic Ozonation of Acid Red 88 from Aqueous Solutions

Degradation of Acid Red 88 (AR 88) azo dye in water was investigated in laboratory-scale experiments in presence of three metal oxide supported catalyst. Oxidation process was monitorized in terms of colour, chemical oxygen demand (COD) and total organic carbon (TOC) removals. Influence of catalysts type and aqueous solution pH were studied.     

Electrochemical behaviour of polyacrylic acid coated gold electrodes: An application to remove heavy metal ions from wastewater

An efficient and low cost preparation method (Diazonium-Induced Anchoring Process) to graft polyacrylic acid (PAA) on the gold substrate has been reported. IR, XPS and AFM techniques were used to characterize the obtained polymer film. The interfacial electrochemistry of the PAA coated gold electrodes was studied by means of impedance spectroscopy and cyclic voltammetry transition techniques. The ability of PAA-grafted onto a gold electrode to reversibly bind or release metal ions was confirmed. As a broad-range chelating material, PAA is able to capture several heavy metal ions at low concentration. The release of those metal ions from the grafted PAA film was obtained under electro-induced-acidification by applying an anodic potential at the electrode to promote a localized water electrolysis. Application of electrochemical-pH-switchable PAA films can be considered within the field of heavy metal waste treatments.     

Controlled Sub‐Micrometer Hierarchical Textures Engineered in Polymeric Fibers and Microchannels via Thermal Drawing

The controlled texturing of surfaces at the micro‐ and nanoscales is a powerful method for tailoring how materials interact with liquids, electromagnetic waves, or biological tissues. The increasing scientific and technological interest in advanced fibers and fabrics has triggered a strong motivation for leveraging the use of textures on fiber surfaces. Thus far however, fiber‐processing techniques have exhibited an inherent limitation due to the smoothing out of surface textures by polymer reflow, restricting achievable feature sizes. In this article, a theoretical framework is established from which a strategy is developed to reduce the surface tension of the textured polymer, thus drastically slowing down thermal reflow. With this approach the fabrication of potentially kilometers‐long polymer fibers with controlled hierarchical surface textures of unprecedented complexity and with feature sizes down to a few hundreds of nanometers is demonstrated, two orders of magnitude below current configurations. Using such fibers as molds, 3D microchannels are also fabricated with textured inner surfaces within soft polymers such as poly(dimethylsiloxane), at dimensions and a degree of simplicity impossible to reach with current techniques. This strategy for the texturing of high curvature surfaces opens novel opportunities in bioengineering, regenerative scaffolds, microfluidics, and smart textiles.     

Application of an objective method for localizing bilateral cortical FDG PET abnormalities to guide the resection of epileptic foci

PURPOSE: In order to improve the objective localization of bilateral cortical abnormalities in positron emission tomography (PET) image volumes, we developed a new three-dimensional image processing technique. The accuracy of this approach with respect to invasive subdural electroencephalography (EEG) data was assessed in a group of children with neocortical epilepsy. METHODS: Glucose PET image volumes were obtained from 12 epileptic children (mean age 5.2 +/- 4.3 years). Bilateral cortical areas of abnormal glucose metabolism were objectively determined using two conditional criteria assessed against a normal database. The normal database was derived from a group of 15 adult controls (mean age 27.6 years). The spatial relationship between seizure onset electrodes and PET abnormalities was assessed using a conventional receiver operating characteristic (ROC) analysis as well as using a newly defined spatial proximity index (SPI), which characterizes the association between adjacent, but not coincident, abnormalities. RESULTS: ROC analysis at the 2 standard deviation (SD) threshold, revealed an accuracy of 65% to detect seizure onset areas with a sensitivity of 64 +/- 17% and a specificity of 66 +/- 24%. Sensitivity decreased to 46 +/- 24% at the 3-SD threshold with a specificity of 80 +/- 21% (accuracy 75%). The average value for the SPI was determined as 3.82 +/- 1.65 which was 20% lower than the SPI value calculated using a simple in-plane two-dimensional asymmetry between homotopic cortical segments (4.52 +/- 3.82). CONCLUSION: The presented image processing technique improves localization of cortical abnormalities and provides valuable imaging clues for placement of subdural EEG grids prior to surgical resection.