Search

Robotic wearable orthosis faces many challenges. A list, but not exhaustive, can include biomechanical coupling, wearability, intention detecting, functional coupling, energy autonomy, trajectory, and torque anticipation. Notably, from a rehabilitative perspective emerges the necessity to define the more proficient rule of interaction to induce learning processes or to support the function when the recovery limit is reached. This study aims to select the optimal solution among the available technologies. We developed an orthosis with a controller that follows the equilibrium-point hypothesis. Three experimental protocols test the transparency and the gait pattern implicit modification during the orthosis use.

These results of an experimental test on a beam built in two phases are described. The beam is made of two concretes, cast at different times and with different strengths. The aim of the experimentation is to study the effect of the construction phases on the stress/strain state and on the ultimate beam capacity. In particular, the flexural behaviour under long-term service loadings has been deeply investigated. The beam has been monitored for about two months under service loads and finally loaded up to failure. A loading history characteristic of that followed during the construction phases has been prescribed. The results are given in terms of strains, deflection and curvature evolutions with time. The experimental behaviour of the beam has been compared with numerical results obtained from simplified and sectional fibre models, and the effect of the construction phases has been investigated. KEYWORDS: concrete, creep, precast beam, experimental test, flexural strength.

In this paper, experimental long-term tests on pultruded GFRP specimens are presented. Both plain composite specimens and specimens stiffened with carbon fiber sheets have been subject to testing. The specimens have been tested under tension and shear for about a 760 days duration, with the load kept constant in time. The specimens under traction loadings have been cut from plates and from the flanges of a wide flange GFRP pultruded beam; the specimens under shear loadings have been extracted from the web of the same beam. Moreover, some specimens have been strengthened by gluing CFRP sheets to both sides, in order to study how their addiction may reduce the specimen deformability under long term loading. The tests have been performed under controlled temperature (20° C) and humidity (60% RH) in a climatic room. The results are given in terms of strains or creep coefficients evolution in time.

Experimental investigations of thermophoretic forces acting upon aerosol particles in the atmosphere are being carried out in cooperation between the Institute of Atmospheric Sciences and Climate (ISAC) of the National Research Council (CNR) of Italy, the Department of Physics of the University of Ferrara, Italy, and the Microgravity Research Centre of the Universite Libre de Bruxelles, Belgium. This experimental task, aiming at understanding the behaviour and distribution of aerosol particles in the atmosphere, is paralleled by the development of a computer program simulating the thermophoretic forces with the Direct Simulation Monte Carlo (DSMC) method of molecular dynamics. Purpose of the computational effort is a better understanding of the experimental data and analysis of thermophoretic forces in regimes, like intermediate Knudsen numbers, where experimental data are not available. The articles explains the details of the application of the DSMC method to the simulation of thermophoretic forces and of the calculation of the temperature distribution in the simulated aerosol particle, which is essential to compute the energy exchanged between particle and colliding air molecules. Preliminary computational data are compared with experiments, providing information about the suitability of the computational approach followed. Order of magnitude of computed thermophoretic velocities agree fairly with experimental data. To reduce statistical scattering of computed results it would be necessary to simulate a larger number of sample molecules and perform three-dimensional simulations with massive parallel computers.

International audience; no abstract

International audience; Coupling between creep and damage is studied in order to properly describe tertiary creep of concrete. Evolution of damage is governed by a strain tensor through an energy norm, obtained by weighting total and elastic strain tensor by means of a constant parameter. In fact, previous analyses show that, if coupling between creep and damage rely upon total strains, tertiary creep occurs too early. In this study, damage model with bilinear constitutive law and Benboudjema's creep model are employed. Numerical simulations provide the structural response after the introduction of the coefficient.

Napoli

Muscular fatigue is a biological situation which is very difficult to quantify. The Authors studied through a computer analysis the power spectrum of electromyogram, recorded from abductor digiti minimi muscle during maximal and minimal contraction effort before and after fatigue and after muscle prolonged relaxation in 8 normal subjects. No significant spectrum differences were found between maximal and minimal effort in each trial, and between the spectra obtained before fatigue and after muscle prolonged relaxation. On the contrary significant differences were found between the spectra obtained after fatigue and the other conditions. The power spectrum analysis appears, also, to be a reliable neurophysiological parameter for the study of biological aspects of muscular fatigue.

The Authors have studied the behaviour of checkerboard pattern visual evoked potential (VEP) latencies by using different spatial frequency stimuli and different stimulating visual fields in order to demonstrate whether spatial frequency might constitute a parameter capable of exciting different retinal regions like different stimulus fields. According to the recent literature low spatial frequency stimuli generate VEP with latencies which are significantly shorter than high spatial frequency stimuli, making this method more reliable for the differentiation of macular and peripheral retinal fields.