Rupture by damage accumulation in rocks

The deformation of rocks is associated with microcracks nucleation and propagation, i.e. damage. The accumulation of damage and its spatial localization lead to the creation of a macroscale discontinuity, so-called "fault" in geological terms, and to the failure of the material, i.e. a dramatic decrease of the mechanical properties as strength and modulus. The damage process can be studied both statically by direct observation of thin sections and dynamically by recording acoustic waves emitted by crack propagation (acoustic emission). Here we first review such observations concerning geological objects over scales ranging from the laboratory sample scale (dm) to seismically active faults (km), including cliffs and rock masses (Dm, hm). These observations reveal complex patterns in both space (fractal properties of damage structures as roughness and gouge), time (clustering, particular trends when the failure approaches) and energy domains (power-law distributions of energy release bursts). We use a numerical model based on progressive damage within an elastic interaction framework which allows us to simulate these observations. This study shows that the failure in rocks can be the result of damage accumulation

Helsinki-Vantaan lentoaseman tilannekuvakeskus : Häiriö- ja poikkeamatilanteiden eteneminen lentoasemalla

Tämän opinnäytetyön tavoitteena oli selvittää, miten Finavian ylläpitämällä Helsinki-Vantaa lentoasemalla tapahtuvat häiriö- ja poikkeamatilanteet vaikuttavat lentoasemalla toimiviin Finavian omiin organisaatioihin sekä lentoasemalla toimiviin viranomaisiin. Häiriö- ja poikkeamatilanteella tarkoitetaan lentoaseman normaaliin toimintaan häiritsevästi vaikuttavaa tapahtumaa, esimerkiksi sähkökatkoa. Työ tehtiin Helsinki-Vantaa lentoaseman tilannekuvakeskuksen päällikön pyynnöstä. Tilannekuvakeskuksessa huomattiin, että vaikka häiriö- ja poikkeamatilanteessa toiminta eri tahojen kanssa on ollut kitkatonta ja sujuvaa, ei toisen organisaation sisällä tapahtuvasta toiminnasta ollut kuvaa. Työn avulla selvitettiin, onko häiriö- tai poikkeamatilanteella vaikutusta eri organisaatioiden ja viranomaisten toimintaan. Opinnäytetyö auttaa rakentamaan kokonaiskäsitystä poikkeamatilanteiden aiheuttamasta toiminnasta koko lentoaseman alueella. Tätä kautta voidaan myös lisätä ymmärrystä eri organisaatioiden ja viranomaisten välillä. Opinnäytetyö toteutettiin yhteistyössä Helsinki-Vantaa lentoaseman tilannekuvakeskuksen kanssa. Työn edetessä rakennetta muokattiin yhteistyössä tilaajan kanssa niin, että se palvelisi mahdollisimman tarkoituksenmukaisesti eri organisaatioita. Työ toteutettiin tekemällä laadullinen tutkimus, jonka runkona oli puolistrukturoitu haastattelu. Haastatteluita kertyi yhteensä 19 kappaletta ja haastateltavia 21. Haastateltavina olivat Finavian eri organisaatioiden johtajia tai päälliköitä ja lentoaseman toimintaan liittyvien viranomaisten lentoaseman toimipisteiden päälliköt. Työstä rajattiin pois kaupalliset yritykset, koska haastatteluiden määrä olisi kasvanut liian suureksi. Lentoaseman tilannekuvakeskus on luonut useita valmiita toimintamalleja erilaisiin häiriö- ja poikkeamatilanteisiin. Tilannekuvakeskuksen päällikkö valitsi näistä häiriö- ja poikkeamatilanteista ne, jotka ovat todennäköisiä tai merkittäviä ja vaikuttavat haitallisesti lentoaseman toimintaan. Erilaisia häiriö- ja poikkeamatilanteita valikoitui 17 kappaletta. Näiden tilanteiden vaikutuksia ja toimintamalleja käsiteltiin haastatteluissa. Haastatteluissa saatu informaatio liitettiin tilannekuvakeskuksen toimintamalleihin ja luotiin jokaiseen valittuun poikkeamatilanteeseen kronologinen kuvaus eri organisaatioiden toiminnasta. Opinnäytetyöstä on myöhemmin tarkoitus tehdä pelkistetympi käsikirja Finavian ja viranomaisten käyttöön.The aim of this study was to find out how to Finavia’s Helsinki-Vantaa airport take place in crisis and emergency situations and how they affecting operating at the airport Finavia's own organizations as well as authorities operating at the airport. The work was done at the request of the Head of the Helsinki-Vantaa airport operation center. The airport operation center noted that although the crisis and emergency situations operation with various parties has been smooth, but nobody didn’t have a picture how these crisis and emergency situations was handled in the another organizations. The work purpose was to find out whether the fault or deviation situation could affect the functioning of the various organizations and public authorities. The thesis helps to build the overall understanding of the actions caused by the deviation of situations throughout the airport. This period may also increase the understanding of the different organizations and authorities. The research was conducted in cooperation with the Helsinki-Vantaa airport operation center. As work progresses, the structure was modified in cooperation with the client so that it would serve as appropriately as possible the different organizations. The work was carried out by qualitative research, whose backbone was the semi-structured interview. Interviews were a total of 19 tracks and 21 interviewees were interviewed leaders or managers in different organizations and Finavia's airport activities related to airport authorities, heads of offices. Work were excluded trading companies, because the number of interviews had grown too large. The airport operation center has created a number of ready-made models for different crisis and emergency situations. Head of the Centre chose a snapshot of the crisis and emergency situations, those who are likely or significant and adversely affect the operation of the airport. 17 various types of crisis and emergency situations was selected. Effects and models of these situations addressed in the interviews. The information obtained in the interviews attached a airport operation center’s operational models and was created for each selected deviation situation chronological description of the activities of various organizations. The thesis is later to be made simpler manual for use by Finavia and the authorities

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO

X-ray emission from the Sombrero galaxy: discrete sources

We present a study of discrete X-ray sources in and around the bulge-dominated, massive Sa galaxy, Sombrero (M104), based on new and archival Chandra observations with a total exposure of ~200 ks. With a detection limit of L_X = 1E37 erg/s and a field of view covering a galactocentric radius of ~30 kpc (11.5 arcminute), 383 sources are detected. Cross-correlation with Spitler et al.'s catalogue of Sombrero globular clusters (GCs) identified from HST/ACS observations reveals 41 X-rays sources in GCs, presumably low-mass X-ray binaries (LMXBs). We quantify the differential luminosity functions (LFs) for both the detected GC and field LMXBs, whose power-low indices (~1.1 for the GC-LF and ~1.6 for field-LF) are consistent with previous studies for elliptical galaxies. With precise sky positions of the GCs without a detected X-ray source, we further quantify, through a fluctuation analysis, the GC LF at fainter luminosities down to 1E35 erg/s. The derived index rules out a faint-end slope flatter than 1.1 at a 2 sigma significance, contrary to recent findings in several elliptical galaxies and the bulge of M31. On the other hand, the 2-6 keV unresolved emission places a tight constraint on the field LF, implying a flattened index of ~1.0 below 1E37 erg/s. We also detect 101 sources in the halo of Sombrero. The presence of these sources cannot be interpreted as galactic LMXBs whose spatial distribution empirically follows the starlight. Their number is also higher than the expected number of cosmic AGNs (52+/-11 [1 sigma]) whose surface density is constrained by deep X-ray surveys. We suggest that either the cosmic X-ray background is unusually high in the direction of Sombrero, or a distinct population of X-ray sources is present in the halo of Sombrero.Comment: 11 figures, 5 tables, ApJ in pres

Azimuthal anisotropy of charged particles at high transverse momenta in PbPb collisions at sqrt(s[NN]) = 2.76 TeV

The azimuthal anisotropy of charged particles in PbPb collisions at nucleon-nucleon center-of-mass energy of 2.76 TeV is measured with the CMS detector at the LHC over an extended transverse momentum (pt) range up to approximately 60 GeV. The data cover both the low-pt region associated with hydrodynamic flow phenomena and the high-pt region where the anisotropies may reflect the path-length dependence of parton energy loss in the created medium. The anisotropy parameter (v2) of the particles is extracted by correlating charged tracks with respect to the event-plane reconstructed by using the energy deposited in forward-angle calorimeters. For the six bins of collision centrality studied, spanning the range of 0-60% most-central events, the observed v2 values are found to first increase with pt, reaching a maximum around pt = 3 GeV, and then to gradually decrease to almost zero, with the decline persisting up to at least pt = 40 GeV over the full centrality range measured.Comment: Replaced with published version. Added journal reference and DO

Search for new physics with same-sign isolated dilepton events with jets and missing transverse energy

A search for new physics is performed in events with two same-sign isolated leptons, hadronic jets, and missing transverse energy in the final state. The analysis is based on a data sample corresponding to an integrated luminosity of 4.98 inverse femtobarns produced in pp collisions at a center-of-mass energy of 7 TeV collected by the CMS experiment at the LHC. This constitutes a factor of 140 increase in integrated luminosity over previously published results. The observed yields agree with the standard model predictions and thus no evidence for new physics is found. The observations are used to set upper limits on possible new physics contributions and to constrain supersymmetric models. To facilitate the interpretation of the data in a broader range of new physics scenarios, information on the event selection, detector response, and efficiencies is provided.Comment: Published in Physical Review Letter

Compressed representation of a partially defined integer function over multiple arguments

In OLAP (OnLine Analitical Processing) data are analysed in an n-dimensional cube. The cube may be represented as a partially defined function over n arguments. Considering that often the function is not defined everywhere, we ask: is there a known way of representing the function or the points in which it is defined, in a more compact manner than the trivial one

Measurement of jet fragmentation into charged particles in pp and PbPb collisions at sqrt(s[NN]) = 2.76 TeV

Jet fragmentation in pp and PbPb collisions at a centre-of-mass energy of 2.76 TeV per nucleon pair was studied using data collected with the CMS detector at the LHC. Fragmentation functions are constructed using charged-particle tracks with transverse momenta pt > 4 GeV for dijet events with a leading jet of pt > 100 GeV. The fragmentation functions in PbPb events are compared to those in pp data as a function of collision centrality, as well as dijet-pt imbalance. Special emphasis is placed on the most central PbPb events including dijets with unbalanced momentum, indicative of energy loss of the hard scattered parent partons. The fragmentation patterns for both the leading and subleading jets in PbPb collisions agree with those seen in pp data at 2.76 TeV. The results provide evidence that, despite the large parton energy loss observed in PbPb collisions, the partition of the remaining momentum within the jet cone into high-pt particles is not strongly modified in comparison to that observed for jets in vacuum.Comment: Submitted to the Journal of High Energy Physic