Fuzzy Networked Control Systems Design Considering Scheduling Restrictions

Nowadays network control systems present a common approximation when connectivity is the issue to be solved based on time delays coupling from external factors. However, this approach tends to be complex in terms of time delays. Therefore, it is necessary to study the behavior of the delays as well as the integration into differential equations of these bounded delays. The related time delays needs to be known a priory but from a dynamic real-time behavior. To do so, the use of priority dynamic Priority exchange scheduling is performed. The objective of this paper is to show a way to tackle multiple time delays that are bounded and the dynamic response from real-time scheduling approximation. The related control law is designed considering fuzzy logic approximation for nonlinear time delays coupling, where the main advantage is the integration of this behavior through extended state space representation keeping certain linear and bounded behavior and leading to a stable situation during events presentation by guaranteeing stability through Lyapunov

Threading Through Macrocycles Enhances the Performance of Carbon Nanotubes as Polymer Fillers

In this work we study the reinforcement of polymers by mechanically interlocked derivatives of single-walled carbon nanotubes (SWNTs). We compare the mechanical properties of fibers made of polymers and of composites with pristine single-walled carbon nanotubes (SWNTs), mechanically interlocked derivatives of SWNTs (MINTs) and the corresponding supramolecular models. Improvements of both Young's modulus and tensile strength of up to 200 % were observed for the polystyrene-MINTs samples with an optimized loading of just 0.01 wt.%, while the supramolecular models with identical chemical composition and loading showed negligible or even detrimental influence. This behavior is found for three different types of SWNTs and two types of macrocycles. Molecular dynamics simulations show that the polymer adopts an elongated conformation parallel to the SWNT when interacting with MINT fillers, irrespective of the macrocycle chemical nature, whereas a more globular structure is taken upon facing with either pristine SWNTs or supramolecular models. The MINT composite architecture thus leads to a more efficient exploitation of the axial properties of the SWNTs and of the polymer chain at the interface, in agreement with experimental results. Our findings demonstrate that the mechanical bond imparts distinctive advantageous properties to SWNT derivatives as polymer fillers.Comment: 39 pages, 19 figure

Synthesis and Magnetic Characterization of Graphite-Coated Iron Nanoparticles

Graphite-coated iron nanoparticles were prepared from magnetite nanoparticles by chemical vapour deposition (CVD) under methane and hydrogen atmosphere. After being purified from carbon excess, graphite-coated iron nanoparticles were tested for morphological and magnetic properties. It was found that, during the thermal process, magnetite nanoparticles 6 nm in size coalesce and transform into graphite-coated iron 200 nm in size, as revealed by scanning electron microscopy (SEM). Raman characterization assessed that high-quality graphite coats the iron core. Magnetic measurements revealed the phase change (magnetite to iron) as an increase in the saturation magnetization from 50 to 165 emu/g after the CVD process

Barrier formation at metal/organic interfaces: dipole formation and the Charge Neutrality Level

The barrier formation for metal/organic semiconductor interfaces is analyzed within the Induced Density of Interface States (IDIS) model. Using weak chemisorption theory, we calculate the induced density of states in the organic energy gap and show that it is high enough to control the barrier formation. We calculate the Charge Neutrality Levels of several organic molecules (PTCDA, PTCBI and CBP) and the interface Fermi level for their contact with a Au(111) surface. We find an excellent agreement with the experimental evidence and conclude that the barrier formation is due to the charge transfer between the metal and the states induced in the organic energy gap.Comment: 7 pages, Proceedings of ICFSI-9, Madrid, Spain (September 2003), special issue of Applied Surface Science (in press

Mecanismos psicobiológicos y del desarrollo de la reactividad al estrés en roedores y humanos

Important research advances on the psychobiological mechanisms underlying individual differences for stress reactivity have resulted from research in animal models. Animal research has also shed light on the psychobiological correlates for stress reactivity in humans, providing candidate neurochemical mechanisms for human research and suggesting general theoretical models of psychological functioning across species. In this article, the basic neurochemical elements underlying stress reactivity are described. In addition, the probabilistic epigenesis theoretical model is used to introduce the necessary developmental and genetic context for the understanding of the psychobiology of individual differences in stress reactivity. Finally, some previous research and potential avenues of research in posttraumatic stress disorder are described using the concepts that emerged from animal research.La investigación con modelos animales ha tenido un avance importante sobre el conocimiento de los mecanismos psicobiológicos que subyacen a las diferencias individuales que existen con referencia a la reactividad al estrés. La investigación animal también ha ayudado en la comprensión de los correlatos psicobiológicos de la reactividad al estrés en humanos, al sugerir mecanismos neuroquímicos particulares para la investigación y al producir modelos generales de funcionamiento psicológico aplicables en humanos. En este artículo se describen los elementos neuroquímicos básicos de la reactividad al estrés. Adicionalmente, se utiliza el modelo de epigénesis probabilística para incluir los elementos del desarrollo y genéticos que proveen el contexto necesario para la comprensión de las diferencias individuales en la reactividad al estrés. Finalmente, se describen algunos resultados y potenciales avances en la investigación de la psicobiología del trastorno de estrés postraumático en términos de los conceptos que han surgido desde la investigación animal

Epifisiolisis de cabeza de radio asociadas a luxación de codo y reducción espontánea

Realizamos un estudio retrospectivo de 10 casos de la epifisiolisis de cabeza de radio ocurridas durante el periodo 1992 a 1997, con un desplazamiento mayor de 60º que según los criterios de O'Brien corresponderían a un grado III. De todas las revisadas seleccionamos 6 casos en los que había una angulación mayor de 90º, creemos ocurren después de luxación o reducción espontánea de luxación de codo; por ser las más frecuentes, las que más problemas presentan en el tratamiento y las que producen más secuelas. Nuestro objetivo es valorar los resultados obtenidos con nuestros tratamientos y realizar una revisión bibliográfica.We have done a retrospective study of ten cases of radial head epiphysiolysis occurred between 1992 and 1997, displaced more than 60º. (O'Brien's grade III). Amongst them we have selected those which were displaced more than 90º (six cases) probably occurred after an elbow luxation or after the spontaneous reduction of an elbow luxation; because the are more infrequent, more troublesome and they give more secuelae. Our aim is to evaluate the results obtained with the treatment and to review the literature