649 research outputs found

    Exact Refined Buckling Solutions for Laminated Plates Under Uniaxial and Biaxial Loads

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    This paper presents a unified LĂ©vy-type solution procedure for the buckling analysis of both thin and thick composite plates under biaxial loads. The plates are simply-supported at two opposite edges, while the two remaining sides are subjected to any combination of simply-supported, clamped and free conditions. The problem is formulated in the context of a variable-kinematic approach, offering the advantage of automatically handling theories of various order. Both layerwise and equivalent single layer theories are considered. The governing equilibrium equations are derived analytically from the Principle of Virtual Displacements (PVD), and are solved exactly referring to the LĂ©vy-type procedure. The accuracy of the predictions is demonstrated by comparison with results available in literature, including exact 3D solutions. A comprehensive set of benchmark results is provided for plates subjected to different loading and boundary conditions and characterized by various width-to-thickness ratios

    Prediction of Natural Frequencies of Laminated Curved Panels Using Refined 2-D Theories in the Spectral Collocation Method

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    This paper presents a versatile and efficientmodeling and solution framework for free vibration analysis of composite laminated cylindrical and spherical panels modeled according to two-dimensional equivalent singlelayer and layerwise theories of variable order.Aunified formulation of the equations of motion is adopted which can be used for both thin and thick structures. The discretization procedure is based on the spectral collocation method and is presented in a compact matrix form which can be directly and easily implemented. The convergence and accuracy of the proposed approach is evaluated for panels having different boundary conditions, thickness and shallowness ratios, and lamination layups

    The Ritz – Sublaminate Generalized Unified Formulation approach for piezoelectric composite plates

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    This paper extends to composite plates including piezoelectric plies the variable kinematics plate modeling approach called Sublaminate Generalized Unified Formulation (SGUF). Two-dimensional plate equations are obtained upon defining a priori the through-thickness distribution of the displacement field and electric potential. According to SGUF, independent approximations can be adopted for the four components of these generalized displacements: an Equivalent Single Layer (ESL) or Layer-Wise (LW) description over an arbitrary group of plies constituting the composite plate (the sublaminate) and the polynomial order employed in each sublaminate. The solution of the two-dimensional equations is sought in weak form by means of a Ritz method. In this work, boundary functions are used in conjunction with the domain approximation expressed by an orthogonal basis spanned by Legendre polynomials. The proposed computational tool is capable to represent electroded surfaces with equipotentiality conditions. Free-vibration problems as well as static problems involving actuator and sensor configurations are addressed. Two case studies are presented, which demonstrate the high accuracy of the proposed Ritz-SGUF approach. A model assessment is proposed for showcasing to which extent the SGUF approach allows a reduction of the number of unknowns with a controlled impact on the accuracy of the result

    Il Cairo: luoghi semi-ufficiali e personaggi eccentrici nei romanzi di Shalabī e Abū Julayyil

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    Cairo is a constantly expanding and changing megalopolis, whose residents negotiate the binary oppositions of centre/periphery, development/poverty, and local/global. This paper investigates the literary representation of the Egyptian capital in four novels by Shalabi and Abu Julayyil published between 1981 and 2008. Firstly, it overviews recent scholarship about the literary geography of Cairo. Then, it examines the narrative techniques employed by Shalabi and Abu Julayyil to portray semi-official spaces, such as historical palaces now in decline, hash dens, shantytowns, and buildings on the verge of collapse. I argue that these spaces interact with the rest of the city, while developing a highly local culture, embodied by eccentric humorous characters

    Design of a sensor network for the quantitative analysis of sport climbing

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    We describe the design of a modular sensorized climbing wall for motion analysis in a naturalistic environment. The wall is equipped with force sensors to measure interaction forces between the athlete and the wall, which can be used by experienced instructors, athletes, or therapists, to gain insights into the quality of motion. A specifically designed triaxial load cell is integrated into each hold placement, invisible to the climber, and compatible with standard climbing holds. Data collected through the sensors is sent to an app running on a portable device. The wall can be adapted to different uses. To validate our design, we recorded a repeated climbing activity of eleven climbers with varying degrees of expertise. Analysis of the interaction forces during the exercise demonstrates that the sensor network design can provide valuable information to track and analyze exercise performance changes over time. Here we report the design process as well as the validation and testing of the sensorized climbing wall

    Countertransference in Trauma Clinic: A Transitional Breach in the Therapists’ Identity

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    In line with the theoretical elaboration of countertransference in the trauma clinic, this article addresses the therapist’s relationship to the strangeness of the trauma, as well as his/her interaction with the cultural difference of the other, who is in this case, the traumatized patient. Thirty-one therapists were interviewed about their subjective experiences, using the methodology of interpretative phenomenological analysis. This article shows interesting subtleties in countertransference reactions to trauma narratives and sheds light on processes indicative of trauma transmission. Therapists interviewed could express experiencing moments of strangeness and inner disquiet; resonance in the defense mechanisms deployed by therapists and by patients at certain moments of the therapy; resorting to disregarding cultural interpretations/generalizations to make sense of an utterly painful situation and put a protective distance with the patients’ culture of origin

    Building an ecologically valid facial expression database – Behind the scenes

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    Artificial Intelligence (AI) algorithms, together with a general increased computational performance, allow nowadays exploring the use of Facial Expression Recognition (FER) as a method of recognizing human emotion through the use of neural networks. The interest in facial emotion and expression recognition in real-life situations is one of the current cutting-edge research challenges. In this context, the creation of an ecologically valid facial expression database is crucial. To this aim, a controlled experiment has been designed, in which thirty-five subjects aged 18–35 were asked to react spontaneously to a set of 48 validated images from two affective databases, IAPS and GAPED. According to the Self-Assessment Manikin, participants were asked to rate images on a 9-points visual scale on valence and arousal. Furthermore, they were asked to select one of the six Ekman’s basic emotions. During the experiment, an RGB-D camera was also used to record spontaneous facial expressions aroused in participants storing both the color and the depth frames to feed a Convolutional Neural Network (CNN) to perform FER. In every case, the prevalent emotion pointed out in the questionnaires matched with the expected emotion. CNN obtained a recognition rate of 75.02%, computed comparing the neural network results with the evaluations given by a human observer. These preliminary results have confirmed that this experimental setting is an effective starting point for building an ecologically valid database

    NPY1R (neuropeptide Y receptor Y1)

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    Review on NPY1R (neuropeptide Y receptor Y1), with data on DNA, on the protein encoded, and where the gene is implicated

    Natural zeolites chabazite/phillipsite/analcime increase blood levels of antioxidant enzymes

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    Imbalance between reactive oxygen species generation and antioxidant capacity induces a condition known as oxidative stress which is implicated in numerous pathological processes. In this study we evaluated whether natural zeolites chabazite/phillipsite/analcime may affect the levels of different antioxidant enzymes (gluthatione peroxidase, superoxide dismutase, gluthatione reductase), total antioxidant status and oxidative stress in 25 clinically healthy men, both non-smokers and smokers. Measurements were performed on whole blood or on plasma samples before (T0) and after 4-weeks zeolites intake (T1). At T1, gluthatione peroxidase, superoxide dismutase and gluthatione reductase increased compared to T0 levels, both considering all subjects as joint and after subdivision in non-smokers and smokers. Differently, a reduction in total antioxidant status was observed at T1. Anyway, total antioxidant status resulted higher than the reference values in both groups at each time point. A decrease in lipid peroxidation, a major indicator of oxidative stress assessed by monitoring thiobarbituric acid reactive substances, was also observed in all subjects at T1. Our results suggested that chabazite/phillipsite/analcime may help to counteract oxidative stress in apparently healthy subjects exposed to different oxidative stress risk factors, such as smoking, thus representing a particular kind of food with potential antioxidant properties
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