Análise do desempenho de uma nova técnica de reforço ao corte para elementos estruturais de betão armado

A formação de fendas de corte em elementos estruturais reforçados à flexão com materiais compósitos (FRP) deve ser evitada, uma vez que antecipa a ruína do elemento, impossibilitando o total aproveitamento das propriedades oferecidas pelo reforço. Neste trabalho estudou-se o comportamento de provetes de betão armado, reforçados ao corte com varões embebidos em adesivo segundo a técnica de reforço designada por “Core Drilled Mounted” (CDM). Catorze provetes foram divididos em seis grupos, de maneira a estudar influência de alguns parâmetros no desempenho da técnica proposta, designadamente: classe de resistência do betão; tipo de varões; tipo de adesivo; diâmetro dos varões, percentagem de reforço ao corte e existência de pré-fissuração. Os resultados mais significativos obtidos na investigação efectuada são apresentados no presente trabalho

Search for charginos, neutralinos, and gravitinos at LEP

The hep-ex data base was decided not to be an appropriate place to make DELPHI notes public. Sorry for the inconvenience.Comment: the paper should not have been made publi

Exploring the possibilities of a new technique for the shear strengthening of RC elements

In the present work, the possibilities of a CFRP-based strengthening technique, herein designated Core Drilled Mounted (CDM) technique, to increase the shear resistance of reinforced concrete (RC) elements were explored. For this purpose, an exploratory experimental program of short beam shear specimens was carefully carried out with the purpose of capturing the main features of the CFRP bar contribution for the concrete shear resistance. The adopted monitoring system was able of establishing a relationship between crack opening, crack sliding and strains in the CFRP strengthening bar, for each applied load. From the obtained results it was observed that a CFRP reinforcement ratio of 0.2% contributed for a 26% increment in terms of specimen shear resistance. Furthermore, at a crack width of 0.3 mm the strain level in the CFRP was enough significant to show that this is a promising strengthening technique for the shear and punching resistance of RC structures. It was also observed that the contribution of the CFRP bars was more effective when concrete cohesive failure mode occurred, indicating that bar-adhesive debond failure mode should be avoided, which requires to select the most appropriate FRP-adhesive system

A machine learning approach to evaluate the influence of higher-order generalized variables on shell free vibrations

This work focuses on deriving guidelines for choosing structural theories for composite shells using Convolutional Neural Networks (CNN). The Axiomatic/Asymptotic Method (AAM) is used to evaluate higher-order structural theories’ accuracy and computational efficiency based on polynomial expansions. AAM exploits the Carrera Unified Formulation to derive the finite element matrices and obtain natural frequencies. The outcomes of AAM concerning the accuracy and computational cost are used to train CNN for various composite shell configurations. The trained network can then be used as a substitute for finite element models to estimate the accuracy of a given structural theory. The results are provided via Best Theory Diagrams (BTD), in which the set of generalized displacement variables to retain the best accuracy can be read for a given amount of nodal degrees of freedom. Verification is carried out using results from FEM. The results proved the computational efficiency of CNN and highlighted the influence of the shell thickness for the proper choice of the structural theory. Third-order terms and transverse stretching are often necessary to obtain acceptable accuracy

The high-intensity hyperon beam at CERN

A high-intensity hyperon beam was constructed at CERN to deliver Sigma- to experiment WA89 at the Omega facility and operated from 1989 to 1994. The setup allowed rapid changeover between hyperon and conventional hadron beam configurations. The beam provided a Sigma-flux of 1.4 x 10^5 per burst at mean momenta between 330 and 345 Gev/c, produced by about 3 x 10^10 protons of 450 GeV/c . At the experiment target the beam had a Sigma-/pi- ratio close to 0.4 and a size of 1.6 x 3.7 cm^2. The beam particle trajectories and their momenta were measured with a scintillating fibre hodoscope in the beam channel and a silicon microstrip detector at the exit of the channel. A fast transition radiation detector was used to identify the pion component of the beam.Comment: 20 pages, 13 figures. Submitted to Nucl. Instr. Meth.

Thermoelastic micromechanical analysis of CFRP with voids

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

Evaluation of synthetic substituted 1,2-dioxanes as novel agents against human leishmaniasis

The treatment of human leishmaniasis is currently based on few compounds that are highly toxic, expensive and have a high rate of treatment failure. A number of recent studies on new drugs focuses on natural or semi-synthetic compounds. Among them, the endoperoxide artemisinin, extracted from Artemisia annua, and some of its derivatives have shown leishmanicidal activity. In the present work, a series of structurally simple, fully synthetic 1,2-dioxanes were evaluated for in vitro antileishmanial activity against promastigotes of Leishmania donovani; the cytotoxicity for mammalian cells was also assessed. The six most promising compounds in terms of activity and selectivity were further investigated for their antileishmanial activity on the promastigote forms of L. tropica, L. major and L. infantum and against L. donovani amastigotes. The good performance in terms of potency and selectivity makes these six hits promising candidates for a preliminary lead optimization as antileishmanial agents

The Relationship between Knowing Sign Language and Quality of Life among Italian People Who Are Deaf: A Cross-Sectional Study

Deafness is a medical condition with important relational implications. This conditioncould affect well-being and self-esteem and cause social anxiety. Sign language is not only a simplemimic but can be considered as a different kind of communication that could be protective for thosewho have learned it. However, some people do not use sign language because they think it canbe marginalizing. The present study aimed to compare the quality of life (QoL) between peoplewho learned Italian sign language as their first language with those who had never learned it orlearned it later. This cross-sectional study involved 182 deaf Italian adults (70.3% females) who wererecruited from Ente Nazionale Sordi (ENS) and by the main online deafness groups. The presentresults suggest that the deaf condition does not seem to significantly affect the dimensions of QoLpertaining to satisfaction and self-esteem, while it could have an effect on preventing high levels of social anxiety and in particular, the group who learned Italian sign language showed significantlyless social anxiety than those who had never learned it

Scelte ottimizzate di trattamento termico nel rispetto di Sicurezza ed Ambiente

Il processo di fabbricazione di un componente forgiato, fuso o laminato in acciaio speciale vede come fasedeterminante, nel suo percorso tecnologico, necessario per l’ottenimento delle caratteristiche di impiegorichieste, il trattamento termico: infatti, per fare estrinsecare ad un acciaio le caratteristiche ottimali richieste, ènecessario effettuare un mirato trattamento termico, nel rispetto di parametri principali molto selettivi, definitidal progettista e produttore del componente stesso. Gli aspetti per il miglioramento continuo del prodotto e delprocesso di trattamento termico devono essere affrontate in sicurezza e nel rispetto dell’ambiente: è questo unaspetto culturale ed etico, che non deve restare un fatto teorico, ma deve trasformarsi in competenza eprevenzione sui rischi e sulle misure, da attuare sugli impianti e da comunicare e monitorare con continuità. Lamemoria propone una comparazione dei vantaggi e svantaggi nella gestione del processo di tempra, con utilizzodi differenti mezzi di spegnimento quali acqua, fluidi interi base olio e soluzioni sintetiche polimeriche, intermini qualitativi, ambientali e di sicurezza. Segue poi una sintesi delle esperienze condotte da Lucchini RSnell’applicazione di tecnologie di trattamento termico con soluzioni polimeriche Houghton (Aqua-Quench),“spray cooling” e “rim chilling”, affrontate in sicurezza e nel rispetto dell’ambiente