532 research outputs found
Energy harvesting from earthquake for vibration-powered wireless sensors
Wireless sensor networks can facilitate the acquisition of useful data for the assessment and retrofitting of existing structures and infrastructures. In this perspective, recent studies have presented numerical and experimental results about self-powered wireless nodes for structural monitoring applications in the event of earthquake, wherein the energy is scavenged from seismic accelerations. A general computational approach for the analysis and design of energy harvesters under seismic loading, however, has not yet been presented. Therefore, this paper proposes a rational method that relies on the random vibrations theory for the electromechanical analysis of piezoelectric energy harvesters under seismic ground motion. In doing so, the ground acceleration is simulated by means of the Clough-Penzien filter. The considered piezoelectric harvester is a cantilever bimorph modeled as Euler-Bernoulli beam with concentrated mass at the free-end, and its global behavior is approximated by the dynamic response of the fundamental vibration mode only (which is tuned with the dominant frequency of the site soil). Once the Lyapunov equation of the coupled electromechanical problem has been formulated, mean and standard deviation of the generated electric energy are calculated. Numerical results for a cantilever bimorph which piezoelectric layers made of electrospun PVDF nanofibers are discussed in order to understand issues and perspectives about the use of wireless sensor nodes powered by earthquakes. A smart monitoring strategy for the experimental assessment of structures in areas struck by seismic events is finally illustrated
Searches for Clean Anomalous Gauge Couplings effects at present and future colliders
We consider the virtual effects of a general type of Anomalous (triple) Gauge
Couplings on various experimental observables in the process of
electron-positron annihilation into a final fermion-antifermion state. We show
that the use of a recently proposed "-peak subtracted" theoretical
description of the process allows to reduce substantially the number of
relevant parameters of the model, so that a calculation of observability limits
can be performed in a rather simple way. As an illustration of our approach, we
discuss the cases of future measurements at LEP2 and at a new 500 GeV linear
collider.Comment: 23 pages incl. 5 figures (e-mail [email protected]
Invisible Events with Radiative Photons at LEP
A study of the radiative neutrino counting reaction at LEP1 and LEP2 energies is presented. An approximate expression
for the spectrum of the observed photon is derived within the framework of the
-dependent structure function approach. This is compared with an exact
expression and found in agreement within the foreseen experimental accuracy.
This model describing single-photon radiation can be applied to the more
general case of initial-state single-photon emission accompanying invisible
final-state events. Higher-order QED corrections due to undetected
initial-state radiation are also included. The implementation in a Monte Carlo
event generator is briefly described.Comment: 10 pages, LaTeX, 7 figures available via anonymous ftp at:
ftp://cobra1.pv.infn.it/pub/phot/, files fig#n.ps with #=1,...,
Optimal Design of Elastic Circular Plane Arches
Arches represent a structural system adopted in construction practice for thousand years, and they are still widely adopted if large spans have to be covered. The structural efficiency of arches principally depends on the minimization of the eccentricity of the pressure curve, which allow us to reduce their structural weight. Despite the millenarian use and a very abundant literature, there is still scope for design optimization of arches. This study is framed within this context and is focused on plane circular arches under uniformly distributed vertical load and self-weight. The arches are elastically clamped at both end sections. A semianalytical approach is developed to minimize the volume, with the aim of determining the fundamental mechanical parameters governing the optimal design. Finally, the results are charted to allow their use in a design process
Event Generators for Bhabha Scattering
The results obtained by the "Event Generators for Bhabha Scattering" working
group during the CERN Workshop "Physics at LEP2" (1994/1995) are presented.Comment: 70 pages, PostScript file. To appear in the Report of the Workshop on
Physics at LEP2, G. Altarelli T. Sjostrand and F. Zwirner ed
Leptonic - and -decays: mass effects, polarization effects and radiative corrections
We calculate the radiative corrections to the unpolarized and the four
polarized spectrum and rate functions in the leptonic decay of a polarized into a polarized electron. The new feature of our calculation is that we
keep the mass of the final state electron finite which is mandatory if one
wants to investigate the threshold region of the decay. Analytical results are
given for the energy spectrum and the polar angle distribution of the final
state electron whose longitudinal and transverse polarization is calculated. We
also provide analytical results on the integrated spectrum functions. We
analyze the limit of our general results and investigate the
quality of the approximation. In the case we
discuss in some detail the role of the anomalous helicity flip
contribution of the final electron which survives the limit. The
results presented in this 0203048 also apply to the leptonic decays of
polarized -leptons for which we provide numerical results.Comment: 39 pages, 11 postscript figures added. Updated version. Four
references added. A few text improvements. Final version to appear in
Phys.Rev.
Diffractive Photoproduction in the Framework of Fracture Functions
Recent data on diffractive photoproduction of dijets are analyzed within the
framework of fracture functions and paying special attention to the
consequences of the use of different rapidity gap definitions in order to
identify diffractive events. Although these effects are found to be
significant, it is shown that once they are properly taken into account, a very
precise agreement between diffractive DIS and diffractive dijet photoproduction
emerges without any significant hint of hard factorization breaking.Comment: 13 pages, 4 figures. To appear in Phys.Rev.
Hard scattering factorization and light cone hamiltonian approach to diffractive processes
We describe diffractive deeply inelastic scattering in terms of diffractive
parton distributions. We investigate these distributions in a hamiltonian
formulation that emphasizes the spacetime picture of diffraction scattering.
For hadronic systems with small transverse size, diffraction occurs
predominantly at short distances and the diffractive parton distributions can
be studied by perturbative methods. For realistic, large-size systems we
discuss the possibility that diffractive parton distributions are controlled
essentially by semihard physics at a scale of nonperturbative origin of the
order of a GeV. We find that this possibility accounts for two important
qualitative aspects of the diffractive data from HERA: the flat behavior in
beta and the delay in the fall-off with Q^2.Comment: 51 pages, 16 figure
Gas Analysis and Monitoring Systems for the RPC Detector of CMS at LHC
The Resistive Plate Chambers (RPC) detector of the CMS experiment at the LHC
proton collider (CERN, Switzerland) will employ an online gas analysis and
monitoring system of the freon-based gas mixture used. We give an overview of
the CMS RPC gas system, describe the project parameters and first results on
gas-chromatograph analysis. Finally, we report on preliminary results for a set
of monitor RPC.Comment: 9 pages, 8 figures. Presented by Stefano Bianco (Laboratori Nazionali
di Frascati dell'INFN) at the IEEE NSS, San Diego (USA), October 200
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