222 research outputs found

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    Induced Force Hovering of Spherical Robot by Under-Actuated Control of Dual Rotor

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    This chapter discusses the design and modelling of a spherical flying robot. The main objective is to control its hovering and omnidirectional mobility by controlling the air mass differential pressure between two asynchronous coaxial rotors that are aligned collinearly. The spherical robot design has embedded a gyroscopic mechanism of three rings that allow the rotors’ under-actuated mobility with 3DOF. The main objective of this study is to maintain the thrust force with nearly vertical direction. The change in pressure between rotors allows to vary the rotors’ tilt and pitch. The system uses special design propellers to improve the laminar air mass flux. A nonlinear fitting model automatically calibrates the rotors’ angular speed as a function of digital values. This model is the functional form that represents the reference input to control the rotors’ speed, validated by three types controllers: P, PI, and PID. The robot’s thrust and induced forces and flight mechanics are proposed and analysed. The simulation results show the feasibility of the approach

    Cambio de paradigma en la relación alcohol y salud: Cuanto menos, mejor

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    El consumo de bebidas alcohólicas está muy arraigado en la cultura occidental y se relaciona con la mayoría de tradiciones y celebraciones. Sin embargo, este consumo no está exento de riesgos que dependen de la cantidad, frecuencia y patrón de consumo, así como de las características de la persona consumidora como edad, sexo y algunas condiciones de salud. Mientras la evidencia científica acumula pruebas de la toxicidad del alcohol, sigue existiendo una creciente presión para consumirlo. Ello obliga a las autoridades sanitarias a redefinir los límites del consumo de bajo riesgo. El 7,4% de la población adulta española consume diariamente bebidas alcohólicas (Observatorio Español de las Drogas y las Adicciones, 2019). El alcohol es una sustancia adictiva capaz de generar dependencia y que se relaciona con más de 200 problemas de salud (Rehm et al., 2017; World Health Organization, 2018). El consumo de alcohol es el séptimo factor de riesgo tanto para las muertes como para la pérdida de Años de Vida Ajustados por Discapacidad. El único consumo de alcohol que minimiza la pérdida de salud es cero (GBD 2016 Risk Factors Collaborators, 2017). ..

    Coherent pion production in neutrino nucleus collision in the 1 GeV region

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    We calculate cross sections for coherent pion production in nuclei induced by neutrinos and antineutrinos of the electron and muon type. The analogies and differences between this process and the related ones of coherent pion production induced by photons, or the (p,n) and (3He,t)(^3 He, t) reactions are discussed. The process is one of the several ones occurring for intermediate energy neutrinos, to be considered when detecting atmospheric neutrinos. For this purpose the results shown here can be easily extrapolated to other energies and other nuclei.Comment: 13 pages, LaTex, 8 post-script figures available at [email protected]

    Intra-Abdominal Pressure as a Marker of Enteral Nutrition Intolerance in Critically Ill Patients. The PIANE Study

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    To determine whether elevated intra-abdominal pressure (IAP) is associated with a higher rate of enteral nutrition-related gastrointestinal (GI) complications; to assess the value of IAP as a predictor of enteral nutrition (EN) intolerance. Intensive Care Unit (ICU) patients on mechanical ventilation requiring at least 5 days of EN were recruited for a prospective, observational, non-interventional, multicenter study. EN was performed and GI complications were managed with an established protocol. IAP was determined via a urinary catheter. Patients who developed any GI complications were considered as presenting EN intolerance. Variables related to EN, IAP and GI complications were monitored daily. Statistical analysis compared patients without GI complications (group A) vs. GI complications (group B). 247 patients were recruited from 28 participating ICUs (group A: 119, group B: 128). No differences between groups were recorded. Patients in group B (p < 0.001) spent more days on EN (8.1 ± 8.4 vs. 18.1 ± 13.7), on mechanical ventilation (8.0 ± 7.7 vs. 19.3 ± 14.9) and in the ICU (12.3 ± 11.4 vs. 24.8 ± 17.5). IAP prior to the GI complication was (14.3 ± 3.1 vs. 15.8 ± 4.8) (p < 0.003). The best IAP value identified for EN intolerance was 14 mmHg but it had low sensitivity and specificity. Although a higher IAP was associated with EN intolerance, IAP alone did not emerge as a good predictor of EN intolerance in critically ill patients

    El prestigio cultural de la mímesis ritual

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    In general, mimesis can be ritual, visual or cognitive. The oldest mimesis takes place within the framework of rites, but in times of symbolic impoverishment many of them have lost their former vigour and have sometimes been reduced to mere folklore. Plato addressed visual mimesis, who said that it did not allow us to know reality with the depth or perfection with which it was possible to do it through rite or reflection. Aristotle delved into cognitive mimesis, pointing out that from it could be known the laws of nature, its ends and the way in which it operates to achieve them. By analysing these types of mimesis, we will highlight that a legitimate and effective way to reconnect man with the world and with reality is the enhancement of the rite.En general, la mímesis puede ser de orden ritual, visual o cognitiva. La mímesis más antigua tiene lugar en el marco de los ritos, pero en tiempos de empobrecimiento simbólico, muchos de ellos han perdido su antiguo vigor y, a veces, han quedado reducidos a mero folclore. La mímesis visual fue abordada por Platón de la que afirmó que no permitía conocer la realidad con la profundidad ni con la perfección con que era posible hacerlo mediante el rito o la reflexión. Aristóteles profundizó en una mímesis de índole cognitiva, señalando que a partir de ella podían conocerse las leyes de la naturaleza, sus fines y el modo en que opera para conseguirlos. Al analizar estos tipos de mímesis trataremos de poner de relieve que una forma legítima y eficaz de reconectar al hombre con el mundo y con la realidad es la puesta en valor del rito

    Unisolvency for Multivariate Polynomial Interpolation in Coatmèlec Configurations of Nodes

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    A new and straightforward proof of the unisolvability of the problem of multivariate polynomial interpolation based on Coatmèlec configurations of nodes, a class of properly posed set of nodes defined by hyperplanes, is presented. The proof generalizes a previous one for the bivariate case and is based on a recursive reduction of the problem to simpler ones following the so-called Radon–Bézout process.The authors thank to Drs. Mariano Gasca and Juan I. Ramos for pointing us some references and for their useful comments which have greatly improved the presentation. The authors also thank a reviewer for pointing out a mistake in the original Proof of Lemma 5. The research reported in this paper was partially supported by Project MTM2010-19969 from the Ministerio de Ciencia e Innovacion of Spain and Grant PAID-06-09-2734 from the Universidad Politecnica de Valencia. M. A. G. M. acknowledges support from the Spanish Ministry of Science and Education (MEC), Fulbright Commission, and FECYT.García March, MÁ.; Gimenez Palomares, F.; Villatoro, FR.; Pérez Quiles, MJ.; Fernández De Córdoba Castellá, PJ. (2011). Unisolvency for Multivariate Polynomial Interpolation in Coatmèlec Configurations of Nodes. Applied Mathematics and Computation. 217(18):7427-7431. https://doi.org/10.1016/j.amc.2011.02.034S742774312171

    Weak-antilocalization signatures in the magnetotransport properties of individual electrodeposited Bi Nanowires

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    We study the electrical resistivity of individual Bi nanowires of diameter 100 nm fabricated by electrodeposition using a four-probe method in the temperature range 5-300 K with magnetic fields up to 90 kOe. Low-resistance Ohmic contacts to individual Bi nanowires are achieved using a focused ion beam to deposit W-based nanocontacts. Magnetoresistance measurements show evidence for weak antilocalization at temperatures below 10 K, with a phase-breaking length of 100 nm
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