672 research outputs found

    Thermoelastic micromechanical analysis of CFRP with voids

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    The work investigates the effect of dispersed air gaps – voids – within the matrix on the local stress and strain fields and the influence on the thermoelastic properties of carbon fiber reinforced plastic polymers (CFRPs). The micromechanics framework is based on the use of 1D higher-order structural theories obtained via the Carrera Unified Formulation (CUF) and periodic boundary conditions (PBC), including plasticity over the matrix. Voids are randomly generated within the matrix, considering different volume fractions. Moreover, several distributions at the same void volume fraction permit to perform statistical analyses of the results. Based on numerical results, increasing void fractions leads to higher stress and strain values. Regarding the thermoelastic properties, the results show a good agreement with the benchmarks, thus confirming that voids have a remarkable effect on thermoelastic properties

    A series elastic composite actuator for soft arm exosuits

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    Crossmodal perception in virtual reality

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    With the proliferation of low-cost, consumer level, head-mounted displays (HMDs) we are witnessing a reappearance of virtual reality. However, there are still important stumbling blocks that hinder the achievable visual quality of the results. Knowledge of human perception in virtual environments can help overcome these limitations. In this work, within the much-studied area of perception in virtual environments, we look into the less explored area of crossmodal perception, that is, the interaction of different senses when perceiving the environment. In particular, we look at the influence of sound on visual perception in a virtual reality scenario. First, we assert the existence of a crossmodal visuo-auditory effect in a VR scenario through two experiments, and find that, similar to what has been reported in conventional displays, our visual perception is affected by auditory stimuli in a VR setup. The crossmodal effect in VR is, however, lower than that present in a conventional display counterpart. Having asserted the effect, a third experiment looks at visuo-auditory crossmodality in the context of material appearance perception. We test different rendering qualities, together with the presence of sound, for a series of materials. The goal of the third experiment is twofold: testing whether known interactions in traditional displays hold in VR, and finding insights that can have practical applications in VR content generation (e.g., by reducing rendering costs)

    An Application of IoT in a Drone Inspection Service for Environmental Control

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    This paper presents an exploratory activity with a drone inspection service for environmental control. The aim of the service is to provide technical support to decision-makers in environmental risk management. The proposed service uses IoT for the interaction between a mobile application, a Smart City platform, and an Unmanned Aircraft System (UAS). The mobile application allows the users to report risky situations, such as fire ignition, spills of pollutants in water, or illegal dumping; the user has only to specify the class of the event, while the geographical coordinates are automatically taken from device-integrated GPS. The message sent from the mobile application arrives to a Smart City platform, which shows all the received alerts on a 3D satellite map, to support decision-makers in choosing where a drone inspection is required. From the Smart City platform, the message is sent to the drone service operator; a CSV file defining the itinerary of the drone is automatically built and shown through the platform; the drone starts the mission providing a video, which is used by the decision-makers to understand whether the situation calls for immediate action. An experimental activity in an open field was carried out to validate the whole chain, from the alert to the drone mission, enriched by a Smart City platform to enable a decision-maker to better manage the situation

    ROBOT-MEDIATED AND CLINICAL SCALES EVALUATION AFTER UPPER LIMB BOTULINUM TOXIN TYPE A INJECTION IN CHILDREN WITH HEMIPLEGIA

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    Objective: The aim of this pilot study was to examine changes in different aspects of impairment, including spasticity in the upper limbs, of hemiplegic children following botulinum toxin type A intervention. Progress was assessed using standard clinical measurements and a robotic device. Design: Pre-post multiple baseline. Subjects: Six children with hemiplegia. Methods: Botulinium toxin type A injections were administered into the affected upper limb muscles. Outcomes were evaluated before and one month after the injection. Outcome assessments included: Melbourne Scale, Modified Ashworth Scale (MAS) and Passive Range of Motion. Furthermore, a robotic device was employed as an evaluation tool. Results: Patients treated with botulinum toxin type A had significantly greater reduction in spasticity (MAS, p < 0.01), which explains an improvement in upper limb function and quality movement measured with the Melbourne Scale (p < 0.01). These improvements are consistent with robot-based evaluation results that showed statistically significant changes (p < 0.01) following botulinum toxin type A injections. Conclusion: The upper limb performs a wide variety of movements. The multi-joint nature of the task during the robotmediated evaluation required active control of joint interaction forces. There was good correlation between clinical scales and robotic evaluation. Hence the robot-mediated assessment may be used as an additional tool to quantify the degree of motor improvement after botulinum toxin type A injections

    Evidence of Hepatitis E Virus (HEV) infection in human and pigs in Sardinia, Italy

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    Introduction. The aim of this study was to determine the seroprevalence of anti-HEV antibodies in humans sera and to study HEV prevalence in swine from different Sardinian farms, testing viral HEV-RNA in bile samples. Methods. In the first six months of 2008, 532 subjects of whom 402 blood donors and 130 workers at zoonotic risk, were enrolled. Anti-HEV were determined with an enzyme linked immunosorbent assay (ELISA). In positive subjects, RNA was extracted and tested by RT-Nested-PCR. From July 2006 to March 2007, 95 bile samples were collected from randomly selected pigs. RNA was extracted from 250 ?l of bile and tested by RT-Nested-PCR. Results. The overall prevalence of anti-HEV antibodies was 4.3%; 5.0% among blood donors and 2.3% among workers at zoonotic risk, with no statistically significant differences between sex, age classes and occupation. The search for HEV-RNA in the subjects positive for antibodies, gave negative results. HEV genome was detected in 6 of the 95 swine bile samples tested. Sequences were clustered within the genotype 3 and are edited on GenBank under accession number: from FJ850960 to FJ850962 and from FJ883000 to FJ883002. Discussion. The overall prevalence of anti-HEV shows that the virus circulates without giving origin to cases of acute hepatitis. The low prevalence value found in workers at zoonotic risk do not apparently support the hypothesis of professional risk. In this study, HEV-RNA was isolated from pigs in Sardinia for the first time confirming the role of swine as HEV reservoir and the possibility of virus transmission to humans
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