2,168 research outputs found
Pounding Effects in Simply Supported Bridges Accounting for Spatial Variability of Ground Motion: A Case Study
This study carries out a parametrical analysis of the seismic response to asynchronous earthquake ground motion of a long multispan rc bridge, the Fener bridge, located on a high seismicity area in the north-east of Italy. A parametrical analysis has been performed investigating the influence of the seismic input correlation level on the structural response: a series of nonlinear time history analyses have been executed, in which the variation of the frequency content in the accelerograms at the pier bases has been described by considering the power spectral density function (PSD) and the coherency function (CF). In order to include the effects due to the main nonlinear behaviours of the bridge components, a 3D finite element model has been developed, in which the pounding of decks at cap-beams, the friction of beams at bearings, and the hysteretic behaviour of piers have been accounted for. The sensitivity analysis has shown that the asynchronism of ground motion greatly influences pounding forces and deck-pier differential displacements, and these effects have to be accurately taken into account for the design and the vulnerability assessment of long multispan simply supported bridges
"Hollow cathode" gun optics
The generation of an electron beam by a hollow cathode gun in a cusp magnetic field is discussed. Such a gun is proposed for an electron cooling device without toroids. In a section with a homogeneous magnetic field, this beam experiences a disturbance region near the axis where the electron temperature becomes higher. The main purpose of the article is to define conditions for generating the beam so as to restrict the extent of this region as much as possible. It is shown that a state with a virtual cathode in the vicinity of the zero magnetic field point is the most suitable for this aim. The experimental and essential analytical results are presented
Characterisation of an urban bridge portfolio and multi-risk prioritisation accounting for deterioration and seismic vulnerability
This contribution proposes a procedure to prioritise retrofit interventions on stocks of bridges according to their seismic vulnerability. The procedure also combines a previously presented approach to evaluate deterioration effects on bridges at a territorial scale. Thereby, the combi-nation of the two approaches provides a multi-risk classification method for bridge stocks. This method also allows refined prioritisation within each class, based on the proposed quantitative indices and on multicriteria decision-making methods. The method was applied to the bridge stock managed by the municipality of Padova, in North-East Italy. First, an extensive charac-terisation of the analysed stock is provided, according to typological, geometric, and structural parameters. Then, the application of the combined approach is presented, highlighting which bridge types resulted more vulnerable to either seismic actions or deterioration effects
A neurally-interfaced hand prosthesis tuned inter-hemispheric communication
Purpose: This work investigates how a direct bidirectional connection between brain and hand prosthesis modifies the bi-hemispheric sensorimotor system devoted to the movement control of the lost limb. Hand prostheses are often unable to satisfy users' expectations, mostly due to the poor performance of their interfacing system. Neural Interfaces implanted inside nerves of the stump offer the advantage of using the bidirectional neural pathways 'naturally' dispatching signals to control proper hand actions and feed-back sensations. Learning to control a neurally-interfaced hand prosthesis and decode sensory information was previously observed to reduce the inter-hemispheric asymmetry of cortical motor maps and the clinical symptoms of phantom limb syndrome. Methods: Electroencephalographic (EEG) data was analysed using Functional Source Separation (FSS), a semi-blind method that incorporates prior knowledge about the signal of interest into data decomposition to give access to cortical patch activities. Results: Bi-hemispheric cortices showed normalization of their activity (topographical and spectral patterns) and of functional connectivity between homologous hand controlling areas, during the delivery of the motor command to the cybernetic prosthesis. Conclusions: The re-establishment of central-peripheral communication with the lost limb induced by a neurally-interfaced hand prosthesis produces beneficial plastic reorganization, not only restructuring contralateral directly-connected control areas, but also their functional balance within the bi-hemispheric system necessary for motor control
Forward-backward asymmetry of top quark in unparticle physics
The updated CDF measurement of the forward-backward asymmetry (FBA) in the
top quark production p{bar p} -> t{bar t} at Tevatron (with the CMS energy 1.96
TeV) shows a deviation of 2*sigma from the value predicted by the Standard QCD
Model. We present calculation of this quantity in the scenario where colored
unparticle physics contributes to the s-channel of the process, and obtain the
regions in the plane of the unparticle parameters lambda and dU which give the
values of the FBA and of the total t{bar t} production cross section compatible
with the present measurements.Comment: 15 pages, 5 figures; various typos corrected, fig.3 has higher
resolution, Ref.[16](2nd entry) is new; version to appear in Phys.Lett.
Indução da brotação de videira da cultivar niágara rosada com o uso de ERGER® associado a nitrato de cálcio em Botucatu, SP.
A utilização de indutores de brotação em fruteiras de origem de clima temperado é uma prática consolidada em todas regiões do Brasil e do mundo. Em videiras, assim como em outras frutíferas temperadas, o Dormex® é o produto mais utilizado devido sua alta eficiência. Pelo fato de não existir outros promotores de brotação com sua eficácia, seu valor financeiro e elevado nível toxicológico são barreiras que os produtores encaram para manter a produção vitícola. Resultados promissores na literatura indicam que o Erger® associado ao nitrato de cálcio apresentam influencia na brotação de frutíferas de clima temperado
Charge breeding of radioactive ions in an electron cyclotron resonance ion source (ECRIS) at ISOLDE
Long-lived neutral-kaon flux measurement for the KOTO experiment
The KOTO ( at Tokai) experiment aims to observe the CP-violating rare
decay by using a long-lived neutral-kaon
beam produced by the 30 GeV proton beam at the Japan Proton Accelerator
Research Complex. The flux is an essential parameter for the measurement
of the branching fraction. Three neutral decay modes, , , and were used to
measure the flux in the beam line in the 2013 KOTO engineering run. A
Monte Carlo simulation was used to estimate the detector acceptance for these
decays. Agreement was found between the simulation model and the experimental
data, and the remaining systematic uncertainty was estimated at the 1.4\%
level. The flux was measured as per protons on a
66-mm-long Au target.Comment: 27 pages, 16 figures. To be appeared in Progress of Theoretical and
Experimental Physic
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