Fault-tolerant control under controller-driven sampling using virtual actuator strategy

We present a new output feedback fault tolerant control strategy for continuous-time linear systems. The strategy combines a digital nominal controller under controller-driven (varying) sampling with virtual-actuator (VA)-based controller reconfiguration to compensate for actuator faults. In the proposed scheme, the controller controls both the plant and the sampling period, and performs controller reconfiguration by engaging in the loop the VA adapted to the diagnosed fault. The VA also operates under controller-driven sampling. Two independent objectives are considered: (a) closed-loop stability with setpoint tracking and (b) controller reconfiguration under faults. Our main contribution is to extend an existing VA-based controller reconfiguration strategy to systems under controller-driven sampling in such a way that if objective (a) is possible under controller-driven sampling (without VA) and objective (b) is possible under uniform sampling (without controller-driven sampling), then closed-loop stability and setpoint tracking will be preserved under both healthy and faulty operation for all possible sampling rate evolutions that may be selected by the controller

Retrieving shallow shear-wave velocity profiles from 2D seismic-reflection data with severely aliased surface waves

The inversion of surface-wave phase-velocity dispersion curves provides a reliable method to derive near-surface shear-wave velocity profiles. In this work, we invert phase-velocity dispersion curves estimated from 2D seismic-reflection data. These data cannot be used to image the first 50 m with seismic-reflection processing techniques due to the presence of indistinct first breaks and significant NMO-stretching of the shallow reflections. A surface-wave analysis was proposed to derive information about the near surface in order to complement the seismic-reflection stacked sections, which are satisfactory for depths between 50 and 700 m. In order to perform the analysis, we had to overcome some problems, such as the short acquisition time and the large receiver spacing, which resulted in severe spatial aliasing. The analysis consists of spatial partitioning of each line in segments, picking of the phase-velocity dispersion curves for each segment in the f-k domain, and inversion of the picked curves using the neighborhood algorithm. The spatial aliasing is successfully circumvented by continuously tracking the surface-wave modal curves in the f-k domain. This enables us to sample the curves up to a frequency of 40 Hz, even though most components beyond 10 Hz are spatially aliased. The inverted 2D VS sections feature smooth horizontal layers, and a sensitivity analysis yields a penetration depth of 20–25 m. The results suggest that long profiles may be more efficiently surveyed by using a large receiver separation and dealing with the spatial aliasing in the described way, rather than ensuring that no spatially aliased surface waves are acquired.Fil: Onnis, Luciano Emanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Osella, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Carcione, Jose M.. Istituto Nazionale di Oceanografia e di Geofisica Sperimentale; Itali

Controlling the charge transfer flow at the graphene/pyrene-nitrilotriacetic acid interface

The fabrication of highly efficient bio-organic nanoelectronic devices is still a challenge due to the difficulty in interfacing the biomolecular component to the organic counterparts. One of the ways to overcome this bottleneck is to add a self-assembled monolayer (SAM) in between the electrode and the biological material. The addition of a pyrene-nitrilotriacetic acid layer to a graphene metal electrode enhances the charge transfer within the device. Our theoretical calculations and electrochemical results show that the formation of a pyrene-nitrilotriacetic acid SAM enforces a direct electron transfer from graphene to the SAM, while the addition of the Ni2+ cation and imidazole reverses the charge transfer direction, allowing an atomic control of the electron flow, which is essential for a true working device. © 2018 The Royal Society of Chemistry

Language and communication problems in childhood: two cases compilation

Este material tiene el objetivo de servir de apoyo para el trabajo con casos clínicos en contextos de educación superior. Pretende ayudar a comprender las características principales de los trastornos del lenguaje en la infancia e integrar aspectos teórico prácticos a partir de la presentación de casos en el ámbito escolar. Se exponen conceptos básicos sobre el desarrollo del lenguaje y se mencionan los principales trastornos en esta área. A continuación se presentan dos casos que puede servir de ejemplo de dos tipos de trastorno diferentes y usarse como herramienta de apoyo para el trabajo en el aula.This material is intended to support work with clinical cases in higher education contexts. It aims to help understand the main characteristics of language disorders in childhood and the integration of practical and theoretical issues through the presentation of cases in the school environment. This article briefly discusses the basic concepts of language development and is found main disorders or problems affecting language and communication. Below are the cases that can serve as an example of two different types of disorder and be used as a support tool for classroom work

ADHD in preschool children: Detection and Early Intervention

Actualmente, el tema de la detección y la atención temprana del TDAH en niños menores de 6 años, no ha sido aún suficientemente explorado desde la investigación y tampoco desde la práctica. Este trabajo tiene el objetivo de ofrecer información que contribuya a una mejora de la detección e intervención de este trastorno en la etapa preescolar. Se expone una síntesis de las principales manifestaciones clínicas del TDAH en niños y niñas pequeñas y se discute la necesidad de implementar estrategias de identificación y abordaje en el contexto de la atención temprana.Currently, detection and early attention of ADHD in children under 6 years has not been sufficiently explored since the investigation and not from the practice. This work aims to provide information that contributes to improve the detection and intervention of this disorder in the preschool stage. A summary of the main clinical manifestations of ADHD in children and small children is expose and the need to implement strategies for identification and approach in the context of early care is discussed

What type of evaluation is needed to design intervention programs in early care?

En el presente artículo se desarrolla una síntesis sobre los distintos tipos de evaluación que se aplican en el contexto de la atención infantil temprana, haciendo especial hincapié en aquellos procesos de evaluación que son necesario para realizar diseños de intervención ajustadas a las necesidades de cada caso y centrados en la persona. Se analiza la complejidad de este proceso y su aplicación para la mejora de la práctica clínica y educativa.This article summarizes different types of evaluation applied in the context of early childhood care, like detection, screening tests, diagnostic evaluating process, follow up evaluation. Emphasising on those evaluation processes that are necessary to design interventions tailored to the needs of each case and focused on the person. Analyzes the complexity of this process and its usefulness for the improvement of clinical and educational practice. It is evident the need to manage different evaluation strategies to increase the quality of intervention programs