8,332 research outputs found

    Wireless sensors and IoT platform for intelligent HVAC control

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    Energy consumption of buildings (residential and non-residential) represents approximately 40% of total world electricity consumption, with half of this energy consumed by HVAC systems. Model-Based Predictive Control (MBPC) is perhaps the technique most often proposed for HVAC control, since it offers an enormous potential for energy savings. Despite the large number of papers on this topic during the last few years, there are only a few reported applications of the use of MBPC for existing buildings, under normal occupancy conditions and, to the best of our knowledge, no commercial solution yet. A marketable solution has been recently presented by the authors, coined the IMBPC HVAC system. This paper describes the design, prototyping and validation of two components of this integrated system, the Self-Powered Wireless Sensors and the IOT platform developed. Results for the use of IMBPC in a real building under normal occupation demonstrate savings in the electricity bill while maintaining thermal comfort during the whole occupation schedule.QREN SIDT [38798]; Portuguese Foundation for Science & Technology, through IDMEC, under LAETA [ID/EMS/50022/2013

    Gender Matters! Analyzing Global Cultural Gender Preferences for Venues Using Social Sensing

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    Gender differences is a phenomenon around the world actively researched by social scientists. Traditionally, the data used to support such studies is manually obtained, often through surveys with volunteers. However, due to their inherent high costs because of manual steps, such traditional methods do not quickly scale to large-size studies. We here investigate a particular aspect of gender differences: preferences for venues. To that end we explore the use of check-in data collected from Foursquare to estimate cultural gender preferences for venues in the physical world. For that, we first demonstrate that by analyzing the check-in data in various regions of the world we can find significant differences in preferences for specific venues between gender groups. Some of these significant differences reflect well-known cultural patterns. Moreover, we also gathered evidence that our methodology offers useful information about gender preference for venues in a given region in the real world. This suggests that gender and venue preferences observed may not be independent. Our results suggests that our proposed methodology could be a promising tool to support studies on gender preferences for venues at different spatial granularities around the world, being faster and cheaper than traditional methods, besides quickly capturing changes in the real world

    A new species of Honduran \u3ci\u3eStrongylaspis\u3c/i\u3e (Coleoptera: Cerambycidae: Prioninae)

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    Strongylaspis antonkozlovi Galileo and Santos-Silva sp. nov. (Coleoptera: Cerambycidae: Prioninae) is described from Cusuco National Park in Honduras, becoming the second species of the genus known in that country. The new species is compared to S. bullata Bates, 1872, the most similar species

    Integration of solar thermal energy in a conventionaf power plant: The Colon solar project

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    This paper reports on the first phase of the Colón Solar Project, originally conceived as the hybrid repowering of an existing thermal power plant, with the addition of a gas turbine in a topping configuration integrating thermal energy (steam) produced by a solar system. However, the project developed in a changing economic environment, in which a new legal structure, still incomplete, as of January, 1998 has liberalized the electricity generation market. This forced the original configuration to be modified, resulting in an all-new combined cycle with solar energy integrated into a Heat Recovery Boiler. Basic plant engineering placed special emphasis on the most important solar components (heliostat and receiver), and an economic analysis showed that the plant is profitable under the assumptions of the analysis. Nevertheless, the relatively low IRR, as well as the uncertainty of realization of some of those assumptions, made the utility postpone its decision to build the plant

    Temperature-independent torsion sensor based on “figure-of-eight” fiber loop mirror

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    An interrogation sensor system combining the “figure-of-eight” fiber loop mirror using a single directional 3×3 fiber optic coupler was proposed. One fiber loop mirror was formed by inserting a length of high birefringent optical fiber at the input ports of the 3×3 coupler. Splicing the output ports of the 3×3 coupler between them created the other fiber loop mirror. The introduction of this second loop gave rise to two polarization states of light with the same frequency but different optical phase. The mechanical torsion sensing head was located at the second loop and was exhibited an average modulus torsion sensitivity of 7.9×10−4 degree/dB. The performance of the sensor was not affected by environmental temperature variations.info:eu-repo/semantics/publishedVersio

    Foliations by spacelike hypersurfaces on Lorentz manifolds

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    In this work we study the geometric properties of spacelike foliations by hypersurfaces on a Lorentz manifold. We find an equation that relates the foliation with the ambient manifold and apply it to investigate conditions for the leaves being totally umbilical or geodesic. Using the Maximum principle with the mentioned equation we obtain an obstruction for the existence of totally geodesic spacelike foliations in a spacetime with positive Ricci curvature on the direction N
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