210 research outputs found
Ultrasonic roll bite measurements in cold rolling – Roll stress and deformation
In cold rolling of thin metal strip, contact conditions between the work rolls and the strip are of great importance: roll deformations and their effect on strip thickness variation may lead to strip flatness defects and thickness inhomogeneity. To control the process, several online measurements are usually carried out such as the rolling load, forward slip and strip tensions at each stand. Shape defects of the strip are usually evaluated after the last stand of a rolling mill thanks to a flatness measuring roll. However, none of these measurements is made within the roll bite itself due to the harsh conditions taking place in that area.
This paper presents a sensor capable of monitoring roll deformations as well as roll radial stresses in situ and in real time. The sensor emits ultrasonic pulses that reflect from the roll surface. The time-of-flight (ToF) of the pulses is recorded during the testing.
The sensor system was incorporated into a work roll and tested on a pilot rolling mill. Measurements were taken as steel strips were rolled under different strip elongation. Roll deformation and radial stresses obtained from the experimental data are in good agreement with numerical results computed with a cold rolling model developed in non-linear Finite Element software
Search for composite and exotic fermions at LEP 2
A search for unstable heavy fermions with the DELPHI detector at LEP is
reported. Sequential and non-canonical leptons, as well as excited leptons and
quarks, are considered. The data analysed correspond to an integrated
luminosity of about 48 pb^{-1} at an e^+e^- centre-of-mass energy of 183 GeV
and about 20 pb^{-1} equally shared between the centre-of-mass energies of 172
GeV and 161 GeV. The search for pair-produced new leptons establishes 95%
confidence level mass limits in the region between 70 GeV/c^2 and 90 GeV/c^2,
depending on the channel. The search for singly produced excited leptons and
quarks establishes upper limits on the ratio of the coupling of the excited
fermio
Search for lightest neutralino and stau pair production in light gravitino scenarios with stau NLSP
Promptly decaying lightest neutralinos and long-lived staus are searched for
in the context of light gravitino scenarios. It is assumed that the stau is the
next to lightest supersymmetric particle (NLSP) and that the lightest
neutralino is the next to NLSP (NNLSP). Data collected with the Delphi detector
at centre-of-mass energies from 161 to 183 \GeV are analysed. No evidence of
the production of these particles is found. Hence, lower mass limits for both
kinds of particles are set at 95% C.L.. The mass of gaugino-like neutralinos is
found to be greater than 71.5 GeV/c^2. In the search for long-lived stau,
masses less than 70.0 to 77.5 \GeVcc are excluded for gravitino masses from 10
to 150 \eVcc . Combining this search with the searches for stable heavy leptons
and Minimal Supersymmetric Standard Model staus a lower limit of 68.5 \GeVcc
may be set for the stau mas
The ANTARES Optical Module
The ANTARES collaboration is building a deep sea neutrino telescope in the
Mediterranean Sea. This detector will cover a sensitive area of typically 0.1
km-squared and will be equipped with about 1000 optical modules. Each of these
optical modules consists of a large area photomultiplier and its associated
electronics housed in a pressure resistant glass sphere. The design of the
ANTARES optical module, which is a key element of the detector, has been
finalized following extensive R & D studies and is reviewed here in detail.Comment: 26 pages, 15 figures, to be published in NI
Updated precision measurement of the average lifetime of B hadrons
The measurement of the average lifetime of B hadrons using inclusively reconstructed secondary vertices has been updated using both an improved processing of previous data and additional statistics from new data. This has reduced the statistical and systematic uncertainties and gives \tau_{\mathrm{B}} = 1.582 \pm 0.011\ \mathrm{(stat.)} \pm 0.027\ \mathrm{(syst.)}\ \mathrm{ps.} Combining this result with the previous result based on charged particle impact parameter distributions yields \tau_{\mathrm{B}} = 1.575 \pm 0.010\ \mathrm{(stat.)} \pm 0.026\ \mathrm{(syst.)}\ \mathrm{ps.
Invariant mass dependence of particle correlations in hadronic final states from the decay of the Z
LBIC QUANTITATIVE MAPPING
La méthode EBIC, qui consiste à générer des porteurs excédentaires dans le matériau par un faisceau d'électrons et à exploiter les informations contenues dans le courant induit, peut être transposée en utilisant un faisceau de lumière ce qui conduit aux méthodes LBIC. Dans ce papier on donne une revue des paramètres physiques qui peuvent ainsi être étudiés. Comme en microscopie électronique à balayage, des images peuvent être réalisées permettant de mettre en évidence des défauts électriquement actifs dans les dispositifs électroniques. Pour une analyse et une imagerie quantitatives des défauts, les principaux modèles théoriques sont présentés et discutés. On décrit les différentes réalisations en analysant les limitations de la méthode. Des exemples d'applications sont donnés pour des cellules solaires et des transistors de puissance. On examine aussi les moyens d'études des matériaux sans structure de collecte.The method of electron beam induced current (EBIC) characterization has been widely used. However, many of experiments possible with the EBIC mode can be performed using a light-beam as an excitation source. The aim of this paper is to give a review of the physical parameters that may be obtained using the light-beam induced current (LBIC) method. Theoretical models involved for quantitative interpretation of LBIC signal and some typical applications are reviewed. The conditions to obtain quantitative mapping are discussed. Some examples including Schottky barriers, solar cells and bipolar transistor are given
Systeme d'enregistrement multiparametrique destine a l'etude d'une reaction a trois corps par la methode des coincidences
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