2,706 research outputs found

    An IoT Platform Based on Microservices and Serverless Paradigms for Smart Farming Purposes

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    Nowadays, the concept of “Everything is connected to Everything” has spread to reach increasingly diverse scenarios, due to the benefits of constantly being able to know, in real-time, the status of your factory, your city, your health or your smallholding. This wide variety of scenarios creates different challenges such as the heterogeneity of IoT devices, support for large numbers of connected devices, reliable and safe systems, energy efficiency and the possibility of using this system by third-parties in other scenarios. A transversal middleware in all IoT solutions is called an IoT platform. the IoT platform is a piece of software that works like a kind of “glue” to combine platforms and orchestrate capabilities that connect devices, users and applications/services in a “cyber-physical” world. In this way, the IoT platform can help solve the challenges listed above. This paper proposes an IoT agnostic architecture, highlighting the role of the IoT platform, within a broader ecosystem of interconnected tools, aiming at increasing scalability, stability, interoperability and reusability. For that purpose, different paradigms of computing will be used, such as microservices architecture and serverless computing. Additionally, a technological proposal of the architecture, called SEnviro Connect, is presented. This proposal is validated in the IoT scenario of smart farming, where five IoT devices (SEnviro nodes) have been deployed to improve wine production. A comprehensive performance evaluation is carried out to guarantee a scalable and stable platform

    Convertidor resonante con enclave de tensión como amplificador de potencia modulado en fase

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    En esta tesis se analizan y desarrollan los convertidores resonantes con enclave de tensión (CMRC) bajo condiciones de carga variable, con configuraciones de carga serie y paralelo. Estos convertidores son generalmente empleados en aplicaciones industriales tales como balastos electrónicos, conversión continua a continua, etc. También se presenta aquí una aplicación novedosa como amplificador de potencia de radio frecuencia (RF) modulado en fase, para la transmisión de errores en un sistema de posicionamiento global diferencial (DGPS), en la banda de radio faros marítimos (285KHz-325KHz). El CMRC presenta diferentes modos de operación de sus cuatro llaves, entre ellos, el que enciende todas las llaves con cero de tensión (ZVS). Este modo de operación permite reducir las pérdidas de conmutación del convertidor y reduce el número de componentes empleados en las llaves. Mediante modelización por tramos lineales se halla el límite de operación entre conmutación con cuatro llaves en ZVS y el resto de los posibles modos de conmutación. Se obtiene este límite en función de las características del circuito resonante del convertidor para un circuito serie y para un circuito paralelo y de la frecuencia de conmutación. Los resultados se muestran en gráficos empleados para facilitar el diseño de convertidores de uso general. Asimismo se desarrolla un método de modulación por desplazamiento de fase binaria escalonada para ser aplicada al CMRC a fin de que éste mantenga la condición de operación de ZVS en sus cuatro llaves. La modulación escalonada produce desplazamientos de fase distribuidos en varios ciclos de portadora, lo que produce cambios de fase graduales con el propósito de concentrar el espectro ocupado en el canal de transmisión. Para aplicar al amplificador de RF modulado, se modela al filtro T como un circuito equivalente paralelo y se diseña el convertidor para permanecer operando con las llaves en ZVS. Esta condición de operación es garantizada aún con desadaptación entre la impedancia de salida del filtro y la impedancia de la antena, dando robustez al diseño frente a cambios en módulo y fase de la carga (antena, línea de transmisón y acoplador). Se implementó un prototipo siguiendo los pasos de diseño establecidos y se demuestra con resultados experimentales, la validez del análisis teórico. Para aplicar al amplificador de RF modulado, modelizamos al filtro T como un circuito equivalente paralelo y diseñamos el convertidor para permanecer operando con las llaves en ZVS. Esta condición de operación es garantizada aún con desadaptación entre la impedancia de salida del filtro y la impedancia de la antena, dando robustez al diseño frente a cambios en módulo y fase de la carga (antena, línea de transmisón y acoplador). Se implementó un prototipo siguiendo los pasos de diseño establecidos y mostramos con resultados experimentales, la validez del análisis teórico. Implementamos el modulador sobre un dispositivo FPGA que actúa directamente sobre las excitaciones de las llaves del convertidor. Mostramos mediciones efectuadas sobre el conjunto amplificador de potencia - modulador, bajo diferentes escalonamientos de fase.Facultad de Ingenierí

    Personal Anonycloud

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    Personal AnonyCloud es un proyecto que soluciona varios de los principales problemas en redes hoy en día. Por una parte, actualmente las herramientas VPN solo permiten conexiones punto a punto, es decir, cliente a servidor. Con PA podremos conseguir una red VPN compuesta por varios terminales de repetición y por otro lado aumentar la seguridad, debido a que los terminales son propios. Estas máquinas serán creadas bajo demanda en servicios cloud públicos generales, siendo reemplazadas en caso de cualquier tipo de intrusión. Además, PA ofrece una interfaz intuitiva y simple, permitiendo el uso de la herramienta a cualquier persona, sea cual sea su nivel de conocimiento sobre servicios VP

    Fatigue in Continuous Fibre Reinforced Thermoplastic Composites

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    International audienceAdditive manufacturing (AM) technologies have been applied with success in many applications, being fused deposition modelling (FDM) the most widely used AM technique for fabricating thermoplastic pieces. The thermoplastic parts made by FDM present lack of strength and low stiffness, as required for fully functional and load-bearing parts. Due to this restriction, a new technology to reinforce with fibres the thermoplastic filaments was developed in the last years. Continuous fibre reinforced thermoplastic composites (CFRTPC) printers are taking this technology to a whole new level in terms of efficient production and mechanical properties. Static mechanical properties, as well as fatigue behaviour, were studied since in these types of loads a wide range of engineering dynamic applications can be envisaged. Tensile tests were performed to characterise the static mechanical properties. Fatigue tests were done to analyse the durability behaviour of the FDM composite materials, and the fracture surface was analysed by SEM microscopy. The results showed that carbon fibre isotropic layers had the higher ultimate tensile stress, with 165 MPa. From fatigue tests, stress vs. number of cycles curves (S vs Nf) in the temporary life zone were obtained. It is observed from the results that specimens with nylon matrix, triangular filling pattern and matrix density of 20%, reinforced with carbon fibre at 0-degrees, showed bette

    Predictive direct torque control using a cascade asymmetric multilevel converter

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    A Direct Torque Control scheme which regulates the flux and the electromagnetictorque of an induction motor (IM) is presented in this paper. A Cascade Asymmetric Multilevel Converter (CAMC) drives the IM in 7-level mode using a new voltage value for the flying capacitors. An integrated control scheme based on the Finite-Control- Set Model Predictive Control (FCS-MPC) approach undertakes the solution as a unique multi-objective control problem. The algorithm directly selects theswitching states according to a rule of optimization and avoiding the use of modulators and nested controllers.Instituto de Investigaciones en Electrónica, Control y Procesamiento de SeñalesConsejo Nacional de Investigaciones Científicas y Técnica

    Albendazole Solid Dispersions: Influence of Dissolution Medium Composition on In Vitro Drug Release

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    The rate-limiting step to drug absorption is often dissolution from the dosage form, especially for poorly soluble com-pounds. Two possibilities for improving the dissolution of these drugs are to increase the available surface area and to im-prove their apparent solubilities under physiologically relevant conditions with surfactants as wetting agents. Albendazole (ABZ), one of the most effective broad-spectrum antihelminthic agents, has a very low aqueous solubility, which leads to an erratic availability. Solid dispersions (SD) with different amounts of carriers (P188 and PEG6000) were formulated to improve the ABZ dissolution rate. When the dissolution test is used to infer biopharmaceutical properties of the dosage form, it is es-sential that the method simulates the gastrointestinal conditions. The objective of this study was to examine the applicabil-ity of different dissolution media to the evaluation of ABZ and ABZ-SD dissolution rates. Dissolution profiles were performed by the official method (0.1 N HCl) and Simulated Gastric Fluid modified with a surfactant. Wetting was evaluated through the determination of surface tension and contact angle of the solutions. The dissolution rate of ABZ was clearly affected by the variables assessed in this study. These results have implications in the design of physiologically based dissolution media.Fil: González Vidal, Noelia Luján. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Cátedra de Control de Calidad de Medicamentos; ArgentinaFil: Castro, Silvina Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Unidad de Investigación y Desarrollo en Tecnología Farmacéutica. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Unidad de Investigación y Desarrollo en Tecnología Farmacéutica; ArgentinaFil: Sanchez Bruni, Sergio Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de Fisiopatología. Laboratorio de Farmacología; ArgentinaFil: Allemandi, Daniel Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Unidad de Investigación y Desarrollo en Tecnología Farmacéutica. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Unidad de Investigación y Desarrollo en Tecnología Farmacéutica; ArgentinaFil: Palma, Santiago Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Unidad de Investigación y Desarrollo en Tecnología Farmacéutica. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Unidad de Investigación y Desarrollo en Tecnología Farmacéutica; Argentin

    Environmentally Assisted Cracking Behavior of S420 and X80 Steels Containing U-notches at Two DifferentCathodic Polarization Levels: An Approach from the Theory of Critical Distances

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    This paper analyzes, using the theory of critical distances, the environmentally assisted cracking behavior of two steels (S420 and API X80) subjected to two different aggressive environments. The propagation threshold for environmentally assisted cracking (i.e., the stress intensity factor above which crack propagation initiates) in cracked and notched specimens (KIEAC and KN IEAC) has been experimentally obtained under di erent environmental conditions. Cathodic polarization has been employed to generate the aggressive environments, at 1 and 5 mA/cm2, causing hydrogen embrittlement on the steels. The point method and the line method, both belonging to the theory of critical distances, have been applied to verify their capacity to predict the initiation of crack propagation. The results demonstrate the capacity of the theory of critical distances to predict the crack propagation onset under the di erent combinations of material and aggressive environments.The authors of this work would like to express their gratitude to the Spanish Ministry of Science and Innovation for the financial support of the projects MAT2014-58738-C3-3-R and MAT2014-58443-P developed by the University of Cantabria

    Nonlinear dimensionality reduction for parametric problems: a kernel proper orthogonal decomposition

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    This is the peer reviewed version of the following article: Diez, P. [et al.]. Nonlinear dimensionality reduction for parametric problems: a kernel proper orthogonal decomposition. "International journal for numerical methods in engineering", 30 Desembre 2021, vol. 122, núm. 24, p. 7306-7327, which has been published in final form at DOI: 10.1002/nme.6831. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Reduced-order models are essential tools to deal with parametric problems in the context of optimization, uncertainty quantification, or control and inverse problems. The set of parametric solutions lies in a low-dimensional manifold (with dimension equal to the number of independent parameters) embedded in a large-dimensional space (dimension equal to the number of degrees of freedom of the full-order discrete model). A posteriori model reduction is based on constructing a basis from a family of snapshots (solutions of the full-order model computed offline), and then use this new basis to solve the subsequent instances online. Proper orthogonal decomposition (POD) reduces the problem into a linear subspace of lower dimension, eliminating redundancies in the family of snapshots. The strategy proposed here is to use a nonlinear dimensionality reduction technique, namely, the kernel principal component analysis (kPCA), in order to find a nonlinear manifold, with an expected much lower dimension, and to solve the problem in this low-dimensional manifold. Guided by this paradigm, the methodology devised here introduces different novel ideas, namely, 1) characterizing the nonlinear manifold using local tangent spaces, where the reduced-order problem is linear and based on the neighboring snapshots, 2) the approximation space is enriched with the cross-products of the snapshots, introducing a quadratic description, 3) the kernel for kPCA is defined ad hoc, based on physical considerations, and 4) the iterations in the reduced-dimensional space are performed using an algorithm based on a Delaunay tessellation of the cloud of snapshots in the reduced space. The resulting computational strategy is performing outstandingly in the numerical tests, alleviating many of the problems associated with POD and improving the numerical accuracy.Generalitat de Catalunya, 2017-SGR-1278; Ministerio de Ciencia e Innovación, CEX2018-000797-S; PID2020-113463RB-C32; PID2020-113463RB-C33Peer ReviewedPostprint (published version
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