3,500 research outputs found

    Energy harvesting from earthquake for vibration-powered wireless sensors

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    Wireless sensor networks can facilitate the acquisition of useful data for the assessment and retrofitting of existing structures and infrastructures. In this perspective, recent studies have presented numerical and experimental results about self-powered wireless nodes for structural monitoring applications in the event of earthquake, wherein the energy is scavenged from seismic accelerations. A general computational approach for the analysis and design of energy harvesters under seismic loading, however, has not yet been presented. Therefore, this paper proposes a rational method that relies on the random vibrations theory for the electromechanical analysis of piezoelectric energy harvesters under seismic ground motion. In doing so, the ground acceleration is simulated by means of the Clough-Penzien filter. The considered piezoelectric harvester is a cantilever bimorph modeled as Euler-Bernoulli beam with concentrated mass at the free-end, and its global behavior is approximated by the dynamic response of the fundamental vibration mode only (which is tuned with the dominant frequency of the site soil). Once the Lyapunov equation of the coupled electromechanical problem has been formulated, mean and standard deviation of the generated electric energy are calculated. Numerical results for a cantilever bimorph which piezoelectric layers made of electrospun PVDF nanofibers are discussed in order to understand issues and perspectives about the use of wireless sensor nodes powered by earthquakes. A smart monitoring strategy for the experimental assessment of structures in areas struck by seismic events is finally illustrated

    Confirmations That Were Not Meant to Be: Religion, Violence and the Female Body in Un poison violent (2010), Corpo celeste (2011), and Kreuzweg (2014)

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    This article considers the representation of the adolescent female body and the relevance of corporeality in Catholicism in three Western European films, which have at their centre the religious confirmation. These are: Un poison violent (Love Like Poison, 2010, Katell Quilléveré), Corpo celeste (Heavenly Body, 2011, Alice Rohrwacher), and Kreuzweg (Stations of the Cross, 2014, Dietrich Brüggemann). The sacrament of confirmation as portrayed in the three films becomes the axis around which the dynamics of adolescence (i.e., changing body, blossoming sexuality, family conflicts) unfold, opening up a space for the analysis of the interplay between female subjectivities and Catholicism’s regulatory role. We look at the often-subtle violence exerted by Catholicism in an attempt to tame the female body and the ways female adolescents (re)negotiate their identity against the backdrop of religious authority. Our contention is that, in the films, the female protagonists’ subtraction from the confirmation becomes a way to distance themselves from the Catholic obedient body and reaffirm their individual, embodied subjectivity. To this end, we engage with the complex relationship between Catholicism, women, and women’s bodies, exploring the dichotomy between the Catholic ideal, unchangeable body and the continually-changing, desiring female bodies

    Optimization of force-limiting seismic devices connecting structural subsystems

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    This paper is focused on the optimum design of an original force-limiting floor anchorage system for the seismic protection of reinforced concrete (RC) dual wall-frame buildings. This protection strategy is based on the interposition of elasto-plastic links between two structural subsystems, namely the lateral force resisting system (LFRS) and the gravity load resisting system (GLRS). The most efficient configuration accounting for the optimal position and mechanical characteristics of the nonlinear devices is obtained numerically by means of a modified constrained differential evolution algorithm. A 12-storey prototype RC dual wall-frame building is considered to demonstrate the effectiveness of the seismic protection strategy

    Epithelial integrin alpha 6 beta 4: complete primary structure of alpha 6 and variant forms of beta 4.

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    The integrin alpha 6 beta 4 is a heterodimer predominantly expressed by epithelia. While no definite receptor function has yet been assigned to it, this integrin may mediate adhesive and/or migratory functions of epithelial cells. We have determined the complete primary structure of both the alpha 6 and beta 4 subunits from cDNA clones isolated from pancreatic carcinoma cell line libraries. The deduced amino acid sequence of alpha 6 is homologous to other integrin alpha chains (18-26% identity). Antibodies to an alpha 6 carboxy terminus peptide immunoprecipitated alpha 6 beta 4 complexes from carcinoma cells and alpha 6 beta 1 complexes from platelets, providing further evidence for the association of alpha 6 with more than one beta subunit. The deduced amino acid sequence of beta 4 predicts an extracellular portion homologous to other integrin beta chains, and a unique cytoplasmic domain comprised of greater than 1,000 residues. This agrees with the structures of the beta 4 cDNAs from normal epithelial cells (Suzuki, S., and Y. Naitoh. 1990. EMBO [Eur. Mol. Biol. Organ.] J. 9:757-763; Hogervost, F., I. Kuikman, A. E. G. Kr. von dem Borne, and A. Sonnenberg. 1990. EMBO [Eur. Mol. Biol. Organ.] J. 9:765-770). Compared to these structures, however, the beta 4 cDNAs that we have cloned from carcinoma cells contain extra sequences. One of these is located in the 5'-untranslated region, and may encode regulatory sequences. Another specifies a segment of 70 amino acids in the cytoplasmic tail. Amplification by reverse transcription-polymerase chain reaction of mRNA indicated that multiple forms of beta 4 may exist, possibly due to cell-type specific alternative splicing. The unique structure of beta 4 suggests its involvement in novel cytoskeletal interactions. Consistent with this possibility, alpha 6 beta 4 is mostly concentrated on the basal surface of epithelial cells, but does not colocalize with components of adhesion plaques

    Energy harvesting from electrospun piezoelectric nanowires for structural health monitoring of a cable-stayed bridge

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    Wireless monitoring could greatly impact the fields of structural health assessment and infrastructure asset management, but some technological challenges pose unsolved issues toward its reliable use in continuous large-scale applications. Among the others, it is worth highlighting that power supply by means of batteries is usually implemented within wireless sensor networks, even though it causes practical concerns that heavily prevent the development of efficient monitoring systems for large structures and infrastructures. Conversely, scavenging ambient energy can alleviate or eventually eliminate the problem of electrical supply by batteries, a strategy that has emerged in recent years as a promising technological solution for bridges. Within this framework, the present work proposes to harvest ambient-induced vibrations of bridge structures using a new class of piezoelectric textiles. The considered case study is an existing cable-stayed bridge located in Italy along the high-speed road that connects Rome and Naples, for which a recent monitoring campaign has allowed to record the dynamic responses of deck and cables. In order to enhance the electric energy that can be converted from wind- and traffic-induced bridge vibrations, the energy harvester exploits a piezoelectric nanogenerator built using arrays of piezoelectric electrospun nanofibers. Particularly, several fiber arrangements are studied at the nano/micro-scale leading to different macro constitutive laws and different electric energy output. A computational study is performed to demonstrate that such nanogenerator is able to provide higher energy levels from recorded dynamic loading time histories than a standard piezoelectric energy harvester. The feasibility of this piezoelectric nanogenerator for bridge monitoring applications is finally discussed

    Calidad de aire en la ciudad de Rafaela

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    Dentro del ambiente urbano la calidad del aire es afectada fundamentalmente por presencia de sustancias que provienen de los procesos de combustión producidos en los vehículos de transporte público y privado. Los contaminantes primarios más importantes son CO, NOx, SO2, HC, y material particulado. En el presente trabajo se estudia la calidad del aire en zona céntrica de la ciudad de Rafaela, provincia de Santa Fe, Argentina. La ciudad de Rafaela se encuentra en la zona centrooeste de la provincia de Santa Fe. Su población es de 82.530 habitantes y cuenta con un parque automotor de alrededor de 59.679 vehículos. (Datos de INDEC Censo 2001 y RNRPA 2007)

    Validation of an Emission Model for a Marine Diesel Engine with Data from Sea Operations

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    In this study, a model is developed to simulate the dynamics of an internal combustion engine, and it is calibrated and validated against reliable experimental data, making it a tool that can effectively be adopted to conduct emission predictions. In this work, the Ricardo WAVE software is applied to the simulation of a particular marine diesel engine, a four-stroke engine used in the maritime field. Results from the bench tests are used for the calibration of the model. Finally, the calibration of the model and its validation with full-scale data measured at sea are presented. The prediction includes not only the classic engine operating parameters for a comparison with surveys but also an estimate of nitrogen oxide emissions, which are compared with similar results obtained with emission factors. The calibration of the model made it possible to obtain an overlap between the simulation results and real data with an average error of approximately 7% on power, torque, and consumption. The model provides encouraging results, suggesting further applications, such as in the study on transient conditions, coupling of the engine model with the ship model for a complete simulation of the operating conditions, and optimization studies on consumption and emissions. The availability of the emission data during the sea trial and validated simulation results are the strengths and novelties of this work
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