818 research outputs found
IMPACT ENERGY DISSIPATOR WITH VARIABLE STIFFNESS AND DRY FRICTION LAYERS
No full textThis paper presents an experimental and numerical study that allows to evaluate the dissipation of impact energy, proposing a friction damper with the use of layers (LFD) for impact energy dissipation. The study is carried out on a macro scale of contact between the layers and friction elements. The effects of displacement and applied speed are experimentally analyzed. Numerically, the FEM analyses the effects of the preload and the material of the friction layers on the hysteretic behavior of the LFD. The energy dissipation in a cycle increases with respect to the applied displacement. The operating range of the LFD is variable, because the stiffness of the system increases with respect to the applied displacement. The preload applied to the damper varies with respect to the displacement applied. A theoretical approach is established to estimate the energy dissipation of the system with previously defined parameters or, to define the geometry and material of the damper elements for an estimated energy range
Variable structural stiffness in frictional energy dissipation with layer elements
No full textThis paper presents an experimental and numerical study that allows to evaluate the dissipation of impact energy, proposing a friction damper with the use of layers (LFD) for impact energy dissipation. The study is carried out on a macro scale of contact between the layers and friction elements. The effects of displacement and applied speed are experimentally analyzed. Numerically, the FEM analyses the effects of the preload and the material of the friction layers on the hysteretic behavior of the LFD. The energy dissipation in a cycle increases with respect to the applied displacement. The operating range of the LFD is variable, because the stiffness of the system increases with respect to the applied displacement. The preload applied to the damper varies with respect to the displacement applied. A theoretical approach is established to estimate the energy dissipation of the system with previously defined parameters or, to define the geometry and material of the damper elements for an estimated energy range
Canciones de las Americas / Luis Alberto del Parana y su Trio Los Paraguayos
No full textTitre uniforme : [La Cumparsita]Titre uniforme : [Le Chanteur de Mexico]. Extr.Comprend : Pimpollo / MARTINEZ GIL - Muchachita dorada / BARBOZA [i.e. Barbosa] et BASTOS - Mexico / LOPEZ - VINCY et del PARANA - Cancion a Julio Correa / MENDEZ et BASTOS - La cumparsita / RODRIGUEZ - CONTURAI [i.e. Contursi]et MARINO - Cancion de la Americas / AVERIGUAR - Bori bori / WEERSMA et del PARANA - Recuerdo de amor / WEERSMA et del PARANA - Farah Diba / WEERSMA et del PARANA - Choli / FLORES et BASTOS - Besame mucho / VELASQUEZ et S. SYLAR [i.e. Skylar] - Brisa suave / CHAMARRO et LARRAMENDIABnF-Partenariats, Collection sonore - BelieveContient une table des matière
Anodic oxidation of Tartaric acid at different electrode materials
No full textAim of the present communication is to show experimental results, and related conclusions, on the electrochemical oxidation
(EO) of tartaric acid (TA), which has been oxidized at Ti/PbO2, Ti/Pt, Pt and HBDD electrodes at different current densities in acidic media.
TA complete mineralization has been achieved only at HBDD and Ti/PbO2, being higher the faradaic efficiency at the latter electrode.
At Pt electrode, the electroxidation was found to be extremely slow, in acidic conditions. The experimental evidence has shown
that the main factor is the interaction of the organic substrate and hydroxyl radicals with the electrode surface, during TA oxidation. In the case of the EO of oxalic acid (OA) in acidic media that was previously studied, better results were obtained at the Pt electrode, supporting the idea that the interaction of organic substrate with the electrode surface, was the main determining parameter and based on the results here reported, this idea was confirmed for TA, more complex compound than OA
Control de velocidad del motor de CD alimentado por un panel solar con enfoque ADRC
Get PDFEn este trabajo se presenta el diseño e implementación de un sistema que controla la velocidad del motor de CD de la marca Baldor modelo CD3425 que tiene una potencia nominal de 1/4 HP, alimentado por un panel solar de la marca Eco Green Energy modelo EGE-260P-60 situado en el punto de máxima potencia. Para cumplir los objetivos, este sistema contempla la interconexión en cascada de un convertidor CD/CD tipo SEPIC con un convertidor CD/CD tipo reductor. Para situar al panel solar en el punto de máxima potencia se emplea el algoritmo Perturb and Observe, ya que el panel solar no es una fuente de alimentación que proporcione un voltaje y/o corriente constante, sino que su comportamiento es no lineal y depende principalmente del nivel de irradiancia incidente. Los resultados muestran que la energía suministrada por el panel solar situado en el punto de máxima potencia es entre siete y diez veces mayor que cuando no lo está, donde la máxima potencia obtenida experimentalmente fue de 233 con un nivel de irradiancia máximo de 1,263 • −2. Para regular la velocidad del motor de CD se utiliza el controlador por rechazo activo de perturbaciones basado en un observador GPI y en la propiedad de planitud diferencial. Los resultados indican que este controlador mantiene la velocidad deseada de 145 / cuando el motor opera hasta con un 83.1% de su potencia nominal, a pesar de que en el sistema no se mantienen las mismas condiciones ya que son consideradas como perturbaciones que se cancelan mediante su estimación. Debido a que ambos controladores trabajan de manera independiente, el software se implementa en la tarjeta de desarrollo Nexys 4 con un FPGA Artix–7 100T, ya que se utilizaron operaciones concurrentes, la principal ventaja de un FPGA frente a los demás dispositivos digitales. En el diseño e implementación del sistema se sigue la metodología para sistemas empotrados propuesta por A. S. Berger, ya que esta metodología es la que mejor se adapta al sistema porque considera aspectos de diseño, implementación e integración del hardware y software que componen este sistema de aplicación específica
IMS messaging gateway in the Cloud
No full textFor mobile messaging service providers to endure in a competitive and dynamic market, it is vital to be flexible, which involves keeping up to date to technological developments, and to be cost effective. In order for service providers to provide highly available service, the use of Cloud computing technology is a well-suited solution. Cloud computing allows resources to be provided as general utilities, which users can lease and release in an on-demand fashion through the Internet. In this thesis an HTTP based mobile messaging solution is designed, implemented and described and deployed in the Amazon Cloud, with the main goal of determining to what extent the availability of mobile messaging services improves when deployed in the Amazon Cloud. Three testing environments are proposed for deploying mobile messaging services, i.e. using a proprietary server, Auto Scaling service and the Elastic Load Balancing service provided by Amazon. The architectures for all three scenarios are described and illustrated, and a description is provided of their implementation. Based on performance tests executed in all three scenarios the improvement in availability is determined. Also stress tests are executed in all scenarios with the purpose to compare the performance, i.e. the average response time required to process a subscriber’s request for service, of each scenario with each other. A comparison of the test results provides insight into the availability of the tested messaging service, and the relationship that exists between each scenario’s performance.Information ArchitectureComputer ScienceElectrical Engineering, Mathematics and Computer Scienc
Fig_21e.fig
No full textFigure 21. PV system behavioral with 1,186 W/m2: (a) P&O algorithm and ADRC approach control signals, (b) PV cells, DC bus and DC motor terminals voltages, (c) DC motor angular speed (d) PV cells current (e) PV cells power. </p
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