Browsing by Subject "Shape"

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    Calculation of the friction, diffusion and sedimentation coefficients of nanoplatelets of arbitrary shape
    (Elsevier, 2022-12-02) Hernández Cifre, José G.; Rodríguez Schmidt, Ricardo; Almagro Gómez, Carmen M.; García de la Torre, José; Química Física
    We have developed a computational scheme for the calculation of the hydrodynamic properties of nanoplatelets – or flat sheets – of arbitrary shape based on the bead-modeling methodology. The procedure has been implemented in computer codes that interface with the public-domain HYDRO++ program. When the friction coefficient calculated for the model is normalized to the value of an infinitely thin disk having the same surface area, its dependence on thickness normalized to a characteristic length of the platelet surface is very weak and depends just on the shape of the particle and not on its size. This allows for a simplified, general treatment of the dependence on thickness. In addition to examples with various peculiar shapes, we have calculated the friction coefficient of elliptical particles as well as some regular polygons. The results are presented in the form of simple equations relating the friction coefficient to the particle dimensions. The results for the friction coefficient are applied to the formulation of the experimentally measurable diffusion and sedimentation coefficients. The diffusion coefficient has a very weak dependence on thickness so that it can be employed to analyze the geometry of the surface even if the thickness is not precisely determined. However, the sedimentation coefficient depends appreciably on thickness and can be used for its precise determination. A joint analysis of diffusion and sedimentation can provide a complete determination of the nanoplatelet shape, dimensions and mass.
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    SeCoMan: a semantic-aware policy framework for developing privacy-preserving and context-aware smart applications
    (Institute of Electrical and Electronics Engineers, 2014-01-21) García Clemente, Félix Jesús; Gil Pérez, Manuel; Martínez Pérez, Gregorio; Huertas Celdrán, Alberto; Ingeniería de la Información y las Comunicaciones; Facultad de Informática
    This paper is intended to provide a solution for developing context-aware smart applications preserving the users' privacy in the Internet of Things (IoT). In this sense, we present a framework called Semantic Web-based Context Management (SeCoMan) aimed at offering a set of predefined queries to provide applications with information about indoor location of users and objects, as well as context-aware services. SeCoMan uses a semantic-oriented IoT vision where semantic technologies play a key role. In fact, SeCoMan uses Semantic Web for modeling description of things, reasoning over data to infer new knowledge, and defining context-aware policies. SeCoMan also defines a layered architecture, including functions related to the management of the users' privacy in a manner that accommodate IoT requirements, in addition to not affecting system performance nor introducing excessive overheads. A thorough discussion on other related works, together with some experiments to measure the throughput and scalability, confirm that SeCoMan is a solution that improves the most relevant proposals existing so far.