5,665 research outputs found

    Statistical Mesoscopic Hydro-Thermodynamics: The Description of Kinetics and Hydrodynamics of Nonequilibrium Processes in Single Liquids

    Full text link
    Hydrodynamics, a term apparently introduced by Daniel Bernoulli (1700-1783) to comprise hydrostatic and hydraulics, has a long history with several theoretical approaches. Here, after a descriptive introduction, we present so-called mesoscopic hydro-thermodynamics, which is also referred to as higher-order generalized hydrodynamics, built within the framework of a mechanical-statistical formalism. It consists of a description of the material and heat motion of fluids in terms of the corresponding densities and their associated fluxes of all orders. In this way, movements are characterized in terms of intermediate to short wavelengths and intermediate to high frequencies. The fluxes have associated Maxwell-like times, which play an important role in determining the appropriate contraction of the description (of the enormous set of fluxes of all orders) necessary to address the characterization of the motion in each experimental setup. This study is an extension of a preliminary article: Physical Review E \textbf{91}, 063011 (2015)

    Diavideos: a Diabetes Health Video Portal

    Get PDF
    Diavideos1 is a web platform that collects trustworthy diabetes health videos from YouTube and offers them in a easy way. YouTube is a big repository of health videos, but good content is sometimes mixed with misleading and harmful videos such as promoting anorexia [1].Diavideos is a web portal that provides easy access to a repository of trustworthy diabetes videos. This poster describes Diavideos and explains the crawling method used to retrieve these videos from trusted channels

    DRY POWDER FORMULATION FROM PHYSALIS PERUVIANA L. FRUITS EXTRACT WITH ANTIDIABETIC ACTIVITY FORMULATED VIA CO-SPRAY DRYING

    Get PDF
    Objective: To establish the drying conditions of an extract of fruits of Physalis peruviana using spray drying (SD) technique by applying a statistical experimental design (SED), to obtain powders for direct compression, retaining the antidiabetic activity. Methods: A 2[6-2] fractional factorial SED was used to get a suitable SD operating conditions to produce powder extract of P. peruviana with high process yield, acceptable moisture content, good flowability, low hygroscopicity and satisfactory morphological and particle size. Operating variables studied were air inlet temperature, atomization air flow rate, feed-rate pump, aspiration rate, extract concentration and coadjuvant proportion. P. peruviana powder obtained under the operating conditions selected was evaluated by X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC) and by in vitro α-amylase inhibition assay, to prove that the antidiabetic activity was remained after the SD. Results: Injection temperature (120 °C), atomization air flow rate (600 l/h), pump setting (5 %), aspirator setting (100 %), extract concentration (7.5 % p/p) and extract: coadjuvant ratio (1:0.75), were the operational conditions selected. Dry extract showed an amorphous state by XRPD and a probable protective effect of coadjutant on the extract, characterized by DSC and the antidiabetic in vitro assay. Antidiabetic activity of the extract remained after its transformation to a solid state by SD in the chosen conditions. Conclusion: The results suggest that coprocessed extract could be used for the production of compressed solids or employed as an intermediate herbal product for the treatment of diabetes

    Orchestrating mitochondria in neurons: Cytoskeleton as the conductor

    Get PDF
    © 2019 The Authors. Cytoskeleton published by Wiley Periodicals, Inc. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.Mitochondria are crucial to support synaptic activity, particularly through ATP production and Ca2+ homeostasis. This implies that mitochondria need to be well distributed throughout the different neuronal sub-compartments. To achieve this, a tight and precise regulation of several neuronal cytoskeleton players is necessary to transport and dock mitochondria. As post-mitotic cells, neurons are highly dependent on mitochondrial quality control mechanisms and several cytoskeleton proteins have been implicated in mitophagy. Therefore, all of these processes are orchestrated by the crosstalk between mitochondria and the neuronal cytoskeleton to form a coordinated and tuned symphony.The authors are supported by Fundação para a Ciência e Tecnologia, Grant references for CCRPD/BD/135521/2018, AFP PD/BD/114113/2015, VAM IF/01693/2014, Funding reference: UID/BIM/50005/2019, project funded by Fundação para a Ciência e a Tecnologia (FCT)/Ministério da Ciência, Tecnologia e Ensino Superior (MCTES) through Fundos do Orçamento de Estado; by European Research Council, grant ERC-StG-679168; and European Molecular Biology Organization, grant EMBO-IG/3309.info:eu-repo/semantics/publishedVersio

    Market orientation and the synergistic effect of mediating and moderating factors on performance : the case of the fashion cluster

    Get PDF
    It is commonly accepted that a market-oriented behaviour has a positive impact on organizational performance. This study provides additional support for the classical relationship between market orientation and organizational performance and goes further by not only including in the model the mediating role of both the organizational learning and organizational innovation, but also examining the potential moderating impact of the environmental conditions in the previous relationship.The analysis is based on data collected from a sample of 130 Portuguese SME operating in the fashion cluster. Implications and future research questions based on the findings are offered at the conclusion of the paper

    A control system for reducing the hydrogen consumption of PEM fuel cells under parametric uncertainties

    Get PDF
    Este artículo presenta un sistema de control para reducir el consumo de hidrogeno para una celda de combustible de Membrana de Intercambio Protónico, considerando incertidumbres paramétricas. El sistema de control incluye un modelo no lineal en el espacio de estado para la celda de combustible, un filtro de Kalman/estimador, un regulador óptimo cuadrático y algoritmo de seguimiento de puntos de máxima potencia (MPP). El objetivo de control es suministrar la potencia de carga demandada, evitando el agotamiento del oxígeno y minimizando el consumo de hidrógeno por medio de un algoritmo de Perturbación y Observación (P&O). El desempeño del sistema de control es evaluado ante incertidumbres paramétricas al simular escenarios de perdida de desempeño como producto del envejecimiento del compresor. De esta forma, dos escenarios fueron simulados: un primer escenario simula un error entre la ganancia (de lazo abierto) del compresor de la celda de combustible y la del modelo; y un segundo escenario, con un error entre la corriente de pérdidas y del compresor de la celda de combustible con respecto al modelo. Los resultados de simulación muestran que el filtro Kalman/estimador logra contrarrestar las incertidumbres producidas por los cambios paramétricos del sistema. Igualmente, el algoritmo MPP logra suministrar el voltaje del compresor adecuado sin necesidad de un perfil óptimo en condiciones ideales.This paper presents a control system for reducing the hydrogen consumption for a Polymer Electrolyte Membrane fuel cell, also considering parametric uncertainties. The control system is based on a non-linear state space model of the fuel cell, a Kalman filter/estimator, a linear state feedback controller and a Maximum Power Point (MPP) tracking algorithm. The control objective is to supply the requested load power, avoiding oxygen starvation with minimum fuel consumption using a Perturb and Observe (P&O) algorithm. The performance of the control system was assessed under parametric uncertainties by simulating a performance degradation of the compressor due to aging. Thus, two cases were simulated: first, a mismatch between the system and the linear model in the (open-loop) air compressor gain; and second, a mismatch between the system and the linear model in the current compressor and losses. The simulation results showed that the Kalman filter/estimator overcome the uncertainties produced by the parametrical variations. Besides, the P&O algorithm accomplished to provide the suitable compressor voltage without identifying an optimal profile under ideal operating conditions and empirical data

    Photovoltaic System Regulation Based on a PID Fuzzy Controller to Ensure a Fixed Settling Time

    Get PDF
    El objetivo principal de controlar los sistemas fotovoltaicos (PV) es asegurar la máxima extracción de potencia disponible. Estos controladores usualmente combinan la acción de un algoritmo de seguimiento del punto de máxima potencia (MPPT) con un regulador de tensión, el cual tiene la función de rechazar las perturbaciones en los terminales del panel. Estos controladores se basan comúnmente en estructuras PI-PID que requieren modelos linealizados alrededor del punto de operación. Pero, debido a perturbaciones generadas por el ambiente y la carga, el punto de operación cambia drásticamente, lo que dificulta obtener el desempeño deseado. Este artículo propone regular el sistema PV utilizando un controlador Fuzzy-PID, el cual se adapta a los cambios de irradiancia solar y oscilaciones en la carga. Esta característica garantiza un tiempo de establecimiento constante, el cual se requiere para definir de forma precisa el periodo del algoritmo MPPT. En el caso de controladores lineales, el periodo del MPPT se fija en el peor caso (periodo más largo), lo cual genera pérdidas de potencia adicionales al disminuir la velocidad del seguimiento del punto de operación óptimo. La solución propuesta en este artículo mejora la eficiencia general del sistema. Finalmente, la solución se valida con simulaciones en Matlab®.The main objective of the controllers in photovoltaic systems (PV) is to ensure the maximum extraction of the available power. Those controllers usually combine the action of a maximum power point tracking algorithm (MPPT) with a voltage regulator, which has the function of rejecting disturbances at the panel terminals. Such controllers are commonly based on PI and PID structures, it requiring linearized models at an operating point. But, due to disturbances generated by the environment and the load, the operating point of the system changes drastically, which hinder to obtain the desired system performance. This paper proposes to regulate the PV system using a Fuzzy PID controller, which adapts to changes in solar irradiance and load oscillations. This characteristic guarantees a constant settling time, which is required to precisely define the period of the MPPT algorithm. In the case of classical linear controllers, the period of the MPPT algorithm is set to the worst case (longest period) which generates additional power losses by slowing down the tracking of the optimal operating point. Therefore, the solution proposed in this paper improves the overall system efficiency. Finally, such a solution is validated through simulations in Matlab®
    • …
    corecore