The use of the probabilistic analysis called Stress-Strength Interference Method (SSIM) applied to the endurance limit approach is being analyzed. Mean stress effect is often included to modify this ...fatigue limit. Plus, through the use of K factors, the fatigue limit is usually modified to account for the influence of loading mode, temperature, component size, corrosion, roughness... A necessary assumption of the SSIM is that stress and strength are independent. In this study, the independence of stress and strength is discussed. It appears that those variables may be in fact dependent. This error may lead to unconservative reliability predictions.
Copilot Pro® is a method for the initial and regular machine-tools setup, developed by the Symme laboratory of the Savoy University and by the Technical Center of Industries of Screw-machining ...(Ctdec) in France. Its first step is the organization of the different machining operations, in setup steps, themselves subdivided into measuring steps. The second step consists in determining the manufacturing dimensions to measure at the end of each measuring step. Finally, the third step consists in linking the manufacturing dimensions to both the correctors and the tool-dimensions, in the aim of calculating the corrections that have to be done in function of the deviations measured on the manufacturing dimensions. With this method, the steering of an industrial workpiece is performed with two steering parts instead of ten before.
During the last years many test-beam sessions were carried out on each ATLAS subdetector in order to assess the performances in standalone mode. During these tests, different monitoring programs were ...developed to ease the setup of correct running conditions and the assessment of data quality. The experience has converged into a common effort to develop a monitoring program, which aims to be exploitable by various subdetector groups. The requirements which drove the design of the program as well as its architecture are discussed in this paper. Characteristic features of the application are a modular software based on a Finite State Machine core to implement the synchronization with the data acquisition system and exploiting the ROOT Tree as transient data store. The first version of this monitoring program was used for the 2004 ATLAS Combined Test Beam.
ATLAS is one of the four experiments under construction along the Large Hadron Collider (LHC) ring at CERN. The LHC will produce interactions at a center-of-mass energy equal to radics = 14 TeV with ...a frequency of 40 MHz. The detector consists of more than 140 million electronic channels. The challenging experimental environment and the extreme detector complexity impose the necessity of a common, scalable, distributed monitoring framework, which can be tuned for optimal use by different ATLAS sub-detectors at the various levels of the ATLAS data flow. This paper presents the architecture of this monitoring software framework and describes its current implementation, which has already been used at the ATLAS beam test activity in 2004. Preliminary performance results, obtained on a computer cluster consisting of 700 nodes, will also be presented, showing that the performance of the current implementation is within the range of the final ATLAS requirements.
A PMT-Block test bench Adragna, P.; Antonaki, A.; Boudagov, I. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2006, Letnik:
564, Številka:
1
Journal Article
Recenzirano
The front-end electronics of the ATLAS hadronic calorimeter (Tile Cal) is housed in a unit, called
PMT-Block. The PMT-Block is a compact instrument comprising a light mixer, a PMT together with its ...divider and a
3-in-1 card, which provides shaping, amplification and integration for the signals. This instrument needs to be qualified before being assembled on the detector. A PMT-Block test bench has been developed for this purpose. This test bench is a system which allows fast, albeit accurate enough, measurements of the main properties of a complete PMT-Block. The system, both hardware and software, and the protocol used for the PMT-Blocks characterization are described in detail in this report. The results obtained in the test of about 10
000 PMT-Blocks needed for the instrumentation of the ATLAS (LHC-CERN) hadronic Tile Calorimeter are also reported.
The Online Histogram Presenter (OHP) is the ATLAS tool to display histograms produced by the online monitoring system. In spite of the name, the Online Histogram Presenter is much more than just a ...histogram display. To cope with the large amount of data, the application has been designed to minimise the network traffic; sophisticated caching, hashing and filtering algorithms reduce memory and CPU usage. The system uses Qt and ROOT for histogram visualisation and manipulation. In addition, histogram visualisation can be extensively customised through configuration files. Finally, its very modular architecture features a lightweight plug-in system, allowing extensions to accommodate specific user needs. After an architectural overview of the application, the paper is going to present in detail the solutions adopted to increase the performance and a description of the plug-in system.
A search for long-lived particles is performed using a data sample of 4.7 fb-1 from protonaproton collisions at a centre-of-mass energy s = 7 TeV collected by the ATLAS detector at the LHC. No excess ...is observed above the estimated background and lower limits, at 95% confidence level, are set on the mass of the long-lived particles in different scenarios, based on their possible interactions in the inner detector, the calorimeters and the muon spectrometer. Long-lived staus in gauge-mediated SUSY-breaking models are excluded up to a mass of 300 GeV for tan beta = 5 a 20 . Directly produced long-lived sleptons are excluded up to a mass of 278 GeV. R-hadrons, composites of gluino (stop, sbottom) and light quarks, are excluded up to a mass of 985 GeV (683 GeV, 612 GeV) when using a generic interaction model. Additionally two sets of limits on R-hadrons are obtained that are less sensitive to the interaction model for R-hadrons. One set of limits is obtained using only the inner detector and calorimeter observables, and a second set of limits is obtained based on the inner detector alone.
The results of a search for pair production of light top squarks are presented, using 4.7 fb-1 of s = 7 TeV protonaproton collisions collected with the ATLAS detector at the Large Hadron Collider. ...This search targets top squarks with masses similar to, or lighter than, the top quark mass. Final states containing exclusively one or two leptons (e , mu ), large missing transverse momentum, light-flavour jets and b-jets are used to reconstruct the top squark pair system. Event-based mass scale variables are used to separate the signal from a large t t A= background. No excess over the Standard Model expectations is found. The results are interpreted in the framework of the Minimal Supersymmetric Standard Model, assuming the top squark decays exclusively to a chargino and a b-quark, while requiring different mass relationships between the Supersymmetric particles in the decay chain. Light top squarks with masses between 123a167 GeV are excluded for neutralino masses around 55 GeV.
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