ORCID Profile
0000-0001-8971-674X
Current Organisations
CNRS
,
Northeastern University
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Publisher: Trans Tech Publications, Ltd.
Date: 09-2013
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.423-426.1548
Abstract: Steel truss bridge is an important part of transportation hub and lifeline engineering, it recently has attracted more attention on dynamic performance of steel truss bridge. In this paper, the ANSYS software is used to perform the modal analysis of steel truss bridge, and we find that the main bridge are more sensitive to the vertical earthquake (i.e., Y direction). In the earthquake response spectrum analysis on Y direction, we find that the maximum deformation is at mid-span of steel truss bridge. In the transient analysis of seismic waves, under the action of horizontal and vertical earthquake accelerations, the structure displacement dynamic diagram and time-history displacement curve are obtained and some conclusions are drawn.
Publisher: Hindawi Limited
Date: 2015
DOI: 10.1155/2015/678573
Abstract: By using numerical code RFP A 2 D (dynamic version), numerical model is built to investigate the failure process of rock particle under impact loading, and the influence of different impact loading on crushing effect and consumed energy of rock particle s le is analyzed. Numerical results indicate that crushing effect is good when the stress wave litude is close to the dynamic strength of rock it is difficult for rock particle to be broken under too low stress wave litude on the other hand, when stress wave litude is too high, excessive fine particle is produced, and crushing effect is not very good on the whole, and more crushing energy is consumed. Secondly, in order to obtain good crushing effect, it should be avoided that wavelength of impact load be too short. Therefore, it is inappropriate to choose impact rusher with too high power and too fast impact frequency for ore particle.
Publisher: Springer Science and Business Media LLC
Date: 07-2021
DOI: 10.1038/S41567-021-01225-Z
Abstract: Leptons with essentially the same properties apart from their mass are grouped into three families (or flavours). The number of leptons of each flavour is conserved in interactions, but this is not imposed by fundamental principles. Since the formulation of the standard model of particle physics, the observation of flavour oscillations among neutrinos has shown that lepton flavour is not conserved in neutrino weak interactions. So far, there has been no experimental evidence that this also occurs in interactions between charged leptons. Such an observation would be a sign of undiscovered particles or a yet unknown type of interaction. Here the ATLAS experiment at the Large Hadron Collider at CERN reports a constraint on lepton-flavour-violating effects in weak interactions, searching for Z -boson decays into a τ lepton and another lepton of different flavour with opposite electric charge. The branching fractions for these decays are measured to be less than 8.1 × 10 −6 ( e τ ) and 9.5 × 10 −6 ( μ τ ) at the 95% confidence level using 139 fb −1 of proton–proton collision data at a centre-of-mass energy of $$\\sqrt{s}=13\\,{\\rm{TeV}}$$ s = 13 TeV and 20.3 fb −1 at $$\\sqrt{s}=8\\,{\\rm{TeV}}.$$ s = 8 TeV . These results supersede the limits from the Large Electron–Positron Collider experiments conducted more than two decades ago.
Publisher: Springer Science and Business Media LLC
Date: 05-2017
Publisher: American Physical Society (APS)
Date: 26-03-2021
Publisher: Springer Science and Business Media LLC
Date: 12-07-2016
Publisher: Springer Science and Business Media LLC
Date: 29-11-2014
Publisher: Elsevier BV
Date: 04-2015
Publisher: Springer Science and Business Media LLC
Date: 06-2021
Abstract: Fiducial and differential cross-section measurements of W + W − production in association with at least one hadronic jet are presented. These measurements are sensitive to the properties of electroweak-boson self-interactions and provide a test of perturbative quantum chromodynamics and the electroweak theory. The analysis is performed using proton-proton collision data collected at $$ \sqrt{s} $$ s = 13 TeV with the ATLAS experiment, corresponding to an integrated luminosity of 139 fb − 1 . Events are selected with exactly one oppositely charged electron-muon pair and at least one hadronic jet with a transverse momentum of p T 30 GeV and a pseudorapidity of | η | 4 . 5. After subtracting the background contributions and correcting for detector effects, the jet-inclusive W + W − + ≥ 1 jet fiducial cross-section and W + W − + jets differential cross-sections with respect to several kinematic variables are measured. These measurements include leptonic quantities, such as the lepton transverse momenta and the transverse mass of the W + W − system, as well as jet-related observables such as the leading jet transverse momentum and the jet multiplicity. Limits on anomalous triple-gauge-boson couplings are obtained in a phase space where interference between the Standard Model litude and the anomalous litude is enhanced.
Publisher: Springer Science and Business Media LLC
Date: 15-01-2015
Publisher: Trans Tech Publications, Ltd.
Date: 2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.501-504.603
Abstract: Numerical simulations the different rock s le in the uniaxial compression have been conducted using Rock Failure Process Analysis program (RFPA 2D ) to evaluate the effects of joint trace lengths on the overall mechanical behaviour of jointed rock masses in this paper. Numerically simulated stress-strain curve, peak stress, peak strain and failure patterns were compared with the corresponding experimental results. We found that for a series of partially-spanning joint geometries with the same joint orientation, the projected area will be proportional to the square of the trace length. Thus, the relationship between compressive strength and partially-spanning joint geometry for the tests carried out to explore the influence of joint trace length may be expressed as a linear correlation between compressive strength and projected area.Numerical simulations agree well with experimental results.
Publisher: Springer Science and Business Media LLC
Date: 03-2018
Publisher: Elsevier BV
Date: 08-2018
Publisher: Elsevier BV
Date: 2021
Publisher: Trans Tech Publications, Ltd.
Date: 09-2007
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.353-358.993
Abstract: Fracture formation on surfaces of bi-layered materials is studied numerically. A simplified two-layered materials model like growing tree trunk is present. This work is focused on patterns of fractures and fracture saturation. We consider the formation of crack pattern in bark as an ex le of pattern formation due to expansion of one material layer with respect to another. As a result of this expansion, the bark stretches until it reaches its limit of deformation and cracks. A novel numerical code, 3D Realistic Failure Process Analysis code (abbreviated as RFPA3D) is used to obtain numerical solutions. In this numerical code, the heterogeneity of materials is taken into account by assigning different properties to the in idual elements according to statistical distribution function. Elastic-brittle constitutive relation with residual strength for elements and a Mohr-Coulomb criterion with a tensile cut-off are adopted so that the elements may fail either in shear or in tension. The discontinuity feature of the initiated crack is automatically induced by using degraded stiffness approach when the tensile strain of the failed elements reaching a certain value. The different patterns are obtained by varying simulation parameters, the thickness of the material layer. Numerical simulation clearly demonstrates that the stress state transition precludes further infilling of fractures and the fracture spacing reaches constant state,i.e. the socalled fracture saturation. It also indicates that RFPA code is a viable tool for modeling fracture formation and studying fracture patterns.
Publisher: Springer Science and Business Media LLC
Date: 19-04-2021
Abstract: A search for new phenomena with top quark pairs in final states with one isolated electron or muon, multiple jets, and large missing transverse momentum is performed. Signal regions are designed to search for two-, three-, and four-body decays of the directly pair-produced supersymmetric partner of the top quark (stop). Additional signal regions are designed specifically to search for spin-0 mediators that are produced in association with a pair of top quarks and decay into a pair of dark-matter particles. The search is performed using the Large Hadron Collider proton-proton collision dataset at a centre-of-mass energy of $$ \\sqrt{s} $$ s = 13 TeV recorded by the ATLAS detector from 2015 to 2018, corresponding to an integrated luminosity of 139 fb − 1 . No significant excess above the Standard Model background is observed, and limits at 95% confidence level are set in the stop-neutralino mass plane and as a function of the mediator mass or the dark-matter particle mass. Stops are excluded up to 1200 GeV (710 GeV) in the two-body (three-body) decay scenario. In the four-body scenario stops up to 640 GeV are excluded for a stop-neutralino mass difference of 60 GeV. Scalar and pseudoscalar dark-matter mediators are excluded up to 200 GeV when the coupling strengths of the mediator to Standard Model and dark-matter particles are both equal to one and when the mass of the dark-matter particle is 1 GeV.
Publisher: American Physical Society (APS)
Date: 19-02-2021
Publisher: Elsevier BV
Date: 04-2004
Publisher: Springer Science and Business Media LLC
Date: 21-10-2022
Publisher: Springer Science and Business Media LLC
Date: 15-09-2022
Publisher: Springer Science and Business Media LLC
Date: 02-2021
Abstract: A search for the supersymmetric partners of quarks and gluons (squarks and gluinos) in final states containing jets and missing transverse momentum, but no electrons or muons, is presented. The data used in this search were recorded by the ATLAS experiment in proton-proton collisions at a centre-of-mass energy of $$ \\sqrt{s} $$ s = 13 TeV during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb − 1 . The results are interpreted in the context of various R -parity-conserving models where squarks and gluinos are produced in pairs or in association and a neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 2.30 TeV for a simplified model containing only a gluino and the lightest neutralino, assuming the latter is massless. For a simplified model involving the strong production of mass-degenerate first- and second-generation squarks, squark masses below 1.85 TeV are excluded if the lightest neutralino is massless. These limits extend substantially beyond the region of supersymmetric parameter space excluded previously by similar searches with the ATLAS detector.
Publisher: Springer Science and Business Media LLC
Date: 06-2020
Publisher: American Physical Society (APS)
Date: 05-08-2020
Publisher: American Physical Society (APS)
Date: 25-11-2020
Publisher: IOP Publishing
Date: 14-09-2020
Publisher: Springer Science and Business Media LLC
Date: 08-2020
Abstract: The factor of four increase in the LHC luminosity, from 0 . 5 × 10 34 cm − 2 s − 1 to 2 . 0 × 10 34 cm − 2 s − 1 , and the corresponding increase in pile-up collisions during the 2015–2018 data-taking period, presented a challenge for the ATLAS trigger, particularly for those algorithms that select events with missing transverse momentum. The output data rate at fixed threshold typically increases exponentially with the number of pile-up collisions, so the legacy algorithms from previous LHC data-taking periods had to be tuned and new approaches developed to maintain the high trigger efficiency achieved in earlier operations. A study of the trigger performance and comparisons with simulations show that these changes resulted in event selection efficiencies of 98% for this period, meeting and in some cases exceeding the performance of similar triggers in earlier run periods, while at the same time keeping the necessary bandwidth within acceptable limits.
Publisher: Trans Tech Publications, Ltd.
Date: 2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.501-504.399
Abstract: Stability analysis of steep rock bedding slope with weak structure planes using strength reduction method was simulated in this paper. The post processing function can display the development condition of the plastic zone, which is the criterion for instability of the slope. Analysis with working conditions of natural circumstance, after excavation, and the slope reinforced by anchor shank after excavation were put forward. Failure modes and safety coefficients of the slope proved that weak plane is the main factor controlling slope failure. Simulation results shown that strength reduction method is appropriate in predict the shape and position of the potential failure surface of steep rock bedding slope.
Publisher: Springer Science and Business Media LLC
Date: 29-01-2014
Publisher: Springer Science and Business Media LLC
Date: 11-2020
DOI: 10.1140/EPJC/S10052-020-08509-3
Abstract: A search is presented for four-top-quark production using an integrated luminosity of 139 fb $$^{-1}$$ - 1 of proton–proton collision data at a centre-of-mass energy of $$13~\\text {TeV}$$ 13 TeV collected by the ATLAS detector at the LHC. Events are selected if they contain a same-sign lepton pair or at least three leptons (electrons or muons). Jet multiplicity, jet flavour and event kinematics are used to separate signal from the background through a multivariate discriminant, and dedicated control regions are used to constrain the dominant backgrounds. The four-top-quark production cross section is measured to be $$24^{+7}_{-6}$$ 24 - 6 + 7 fb. This corresponds to an observed (expected) significance with respect to the background-only hypothesis of 4.3 (2.4) standard deviations and provides evidence for this process.
Publisher: IOP Publishing
Date: 07-2021
DOI: 10.1088/1748-0221/16/07/P07029
Abstract: The ATLAS experiment at the Large Hadron Collider (LHC) employs a trigger system consisting of a first-level hardware trigger (L1) and a software-based high-level trigger. The L1 muon trigger system selects muon candidates, assigns them to the correct LHC bunch crossing and classifies them into one of six transverse-momentum threshold classes. The L1 muon trigger system uses resistive-plate chambers (RPCs) to generate the muon-induced trigger signals in the central (barrel) region of the ATLAS detector. The ATLAS RPCs are arranged in six concentric layers and operate in a toroidal magnetic field with a bending power of 1.5 to 5.5 Tm. The RPC detector consists of about 3700 gas volumes with a total surface area of more than 4000 m 2 . This paper reports on the performance of the RPC detector and L1 muon barrel trigger using 60.8 fb -1 of proton-proton collision data recorded by the ATLAS experiment in 2018 at a centre-of-mass energy of 13 TeV. Detector and trigger performance are studied using Z boson decays into a muon pair. Measurements of the RPC detector response, efficiency, and time resolution are reported. Measurements of the L1 muon barrel trigger efficiencies and rates are presented, along with measurements of the properties of the selected s le of muon candidates. Measurements of the RPC currents, counting rates and mean avalanche charge are performed using zero-bias collisions. Finally, RPC detector response and efficiency are studied at different high voltage and front-end discriminator threshold settings in order to extrapolate detector response to the higher luminosity expected for the High Luminosity LHC.
Publisher: Springer Science and Business Media LLC
Date: 07-2020
Abstract: A search for Higgs boson pair production via vector-boson fusion (VBF) in the $$ b\\overline{b}b\\overline{b} $$ b b ¯ b b ¯ final state is carried out with the ATLAS experiment using 126 fb − 1 of proton- proton collision data delivered at $$ \\sqrt{s} $$ s = 13 TeV by the Large Hadron Collider. This search is sensitive to VBF production of additional heavy bosons that may decay into Higgs boson pairs, and in a non-resonant topology it can constrain the quartic coupling between the Higgs bosons and vector bosons. No significant excess relative to the Standard Model expectation is observed, and limits on the production cross-section are set at the 95% confidence level for a heavy scalar resonance in the context of an extended Higgs sector, and for non-resonant Higgs boson pair production. Interpretation in terms of the coupling between a Higgs boson pair and two vector bosons is also provided: coupling values normalised to the Standard Model expectation of κ 2 V − 0 . 76 and κ 2 V 2 . 90 are excluded at the 95% confidence level in data.
Publisher: Elsevier BV
Date: 08-2021
Publisher: Springer Science and Business Media LLC
Date: 14-11-2014
Publisher: Springer Science and Business Media LLC
Date: 10-2020
Publisher: American Physical Society (APS)
Date: 13-08-2020
Publisher: Trans Tech Publications, Ltd.
Date: 03-2008
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.33-37.631
Abstract: Rock is a typical non-homogeneous material. The behavior of a rock block under compression and the process of micro-fracture in that block are phenomena of considerable interest in understanding the strength characterization of brittle rock. In this study, the effect of the non-homogeneity on limit bearing capacity of rock block based on Rock Elasto-Plastic Failure Process Analysis code (REPFPA) are simulated and investigated. Numerical simulations find out that there exists a functional relation between the heterogeneity coefficient and the limit bearing capacity of rock block. For specimens with the same heterogeneity, however, the numerical simulations show that the failure modes depend greatly on the crack initiation location, which is found to be sensitive to the local disorder features within the specimen. In addition, the characteristics of acoustic emissions with the changing of heterogeneity coefficient were also found. These identifications are crucial for better understanding and interpreting the experimental results and consequently, improve our concepts in design or analysis of rock engineering structures.
Publisher: Springer Science and Business Media LLC
Date: 14-08-2017
DOI: 10.1038/NPHYS4208
Publisher: Springer Science and Business Media LLC
Date: 04-2021
Abstract: The results of a search for direct pair production of top squarks and for dark matter in events with two opposite-charge leptons (electrons or muons), jets and missing transverse momentum are reported, using 139 fb − 1 of integrated luminosity from proton-proton collisions at $$ \\sqrt{s} $$ s = 13 TeV, collected by the ATLAS detector at the Large Hadron Collider during Run 2 (2015–2018). This search considers the pair production of top squarks and is sensitive across a wide range of mass differences between the top squark and the lightest neutralino. Additionally, spin-0 mediator dark-matter models are considered, in which the mediator is produced in association with a pair of top quarks. The mediator subsequently decays to a pair of dark-matter particles. No significant excess of events is observed above the Standard Model background, and limits are set at 95% confidence level. The results exclude top squark masses up to about 1 TeV, and masses of the lightest neutralino up to about 500 GeV. Limits on dark-matter production are set for scalar (pseudoscalar) mediator masses up to about 250 (300) GeV.
Publisher: Springer Science and Business Media LLC
Date: 06-2021
DOI: 10.1140/EPJC/S10052-021-09192-8
Abstract: The paper presents a measurement of the Standard Model Higgs Boson decaying to b -quark pairs in the vector boson fusion (VBF) production mode. A s le corresponding to 126 $$\\hbox {fb}^{-1}$$ fb - 1 of $$\\sqrt{s} = 13\\,\\text {TeV}$$ s = 13 TeV proton–proton collision data, collected with the ATLAS experiment at the Large Hadron Collider, is analyzed utilizing an adversarial neural network for event classification. The signal strength, defined as the ratio of the measured signal yield to that predicted by the Standard Model for VBF Higgs production, is measured to be $$0.95^{+0.38}_{-0.36}$$ 0 . 95 - 0.36 + 0.38 , corresponding to an observed (expected) significance of 2.6 (2.8) standard deviations from the background only hypothesis. The results are additionally combined with an analysis of Higgs bosons decaying to b -quarks, produced via VBF in association with a photon.
Publisher: Trans Tech Publications, Ltd.
Date: 12-2013
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.477-478.531
Abstract: Based on the fluid-solid coupling theory, we describe the fractured rock mass as a continuous porous medium and consider the rock mass permeability coefficient a function of the stress and strain. By using the multi-physics coupling analysis software COMSOL, we achieved the dynamic change of permeability coefficient, and found that serious damage due to micro cracking occurred in the excavated damage zone of rock mass due to the yield and failure of rock mass. Corrodingly, permeability will remarkably increase, which is basically consistent with the experimental results. The simulations indicated the "indirect coupling" effect of seepage and stress. Therefore, the coupled analysis of the seepage and stress in fractured rock masses is important for the practical rock mechanics and rock engineering.
Publisher: Springer Science and Business Media LLC
Date: 05-2021
Abstract: The results of a search for new phenomena in final states with b -jets and missing transverse momentum using 139 fb − 1 of proton-proton data collected at a centre-of-mass energy $$ \\sqrt{s} $$ s = 13 TeV by the ATLAS detector at the LHC are reported. The analysis targets final states produced by the decay of a pair-produced supersymmetric bottom squark into a bottom quark and a stable neutralino. The analysis also seeks evidence for models of pair production of dark matter particles produced through the decay of a generic scalar or pseudoscalar mediator state in association with a pair of bottom quarks, and models of pair production of scalar third-generation down-type leptoquarks. No significant excess of events over the Standard Model background expectation is observed in any of the signal regions considered by the analysis. Bottom squark masses below 1270 GeV are excluded at 95% confidence level if the neutralino is massless. In the case of nearly mass-degenerate bottom squarks and neutralinos, the use of dedicated secondary-vertex identification techniques permits the exclusion of bottom squarks with masses up to 660 GeV for mass splittings between the squark and the neutralino of 10 GeV. These limits extend substantially beyond the regions of parameter space excluded by similar ATLAS searches performed previously.
Publisher: Elsevier BV
Date: 02-2023
Publisher: American Physical Society (APS)
Date: 17-12-2020
Publisher: Springer Science and Business Media LLC
Date: 21-11-2019
Publisher: Elsevier BV
Date: 06-2016
Publisher: Trans Tech Publications, Ltd.
Date: 07-2011
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.268-270.857
Abstract: In this paper, the bond length effect of FRP plate on bonding performance and the distribution patterns of the stress in FRP plate was investigated using 3D Realistic Failure Process Analysis (RFPA 3D ) code to study the debonding mechanism of the FRP plate bonded to concrete block. Numerical simulations show that the progressive debonding of FRP plate bonded to concrete occurs in the concrete on the condition of different bond lengths can be ided into four stages: elastic-deformation stage, elastic-softening stage, elastic-softening-debonding stage and softening-debonding stage. It is also show that the interfacial bond strength and the global slip of FRP-to-concrete increase with the increase of the bond length.
Publisher: American Physical Society (APS)
Date: 14-08-2020
Publisher: Trans Tech Publications, Ltd.
Date: 03-2008
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.33-37.609
Abstract: Rock permeability is important in civil and geo-hydraulic engineering, the mining and petroleum industries, and in environmental and engineering geology. In this paper, considering the mutual hydro-mechanical response between stress-induced permeability and damage, a coupled mathematical model for solid deformation and gas flow in the coal or rock was established and an attempt is made to investigate the rock permeability evolution, fracture patterns, and flow vectors in rock s les at the scale of usual laboratory s les as well as the relation between permeability and stress induced damage in connection with the complete strain-stress process of loaded rocks. Numerical simulations show that the permeability of rock was not constant, closely related to the state of stress, but varied with the stress and strain states in the rocks. Microcracking, resulting from the concentration of stress on relatively weak rock elements, triggers successive crack initiation and propagation that in turn leads to permeability enhancement. Prior to the peak strength, the permeability decreases with increasing load. A dramatic increase in permeability occurs in the post-peak stress-strain region due to the catastrophic collapse of microstructure in rock. Moreover, the permeability of rock in post-peak stress-strain region is much higher that that of in pre-peak region. Such intensive studies of gas flow in stressed heterogeneous rocks are useful as initial approaches to many engineering problems in mining and petroleum industries.
Publisher: Elsevier BV
Date: 11-2017
Publisher: Springer Science and Business Media LLC
Date: 06-12-2014
Publisher: Elsevier BV
Date: 06-2018
Publisher: American Physical Society (APS)
Date: 18-12-2020
Publisher: Springer Science and Business Media LLC
Date: 06-2021
Abstract: A search for charged Higgs bosons decaying into W ± W ± or W ± Z bosons is performed, involving experimental signatures with two leptons of the same charge, or three or four leptons with a variety of charge combinations, missing transverse momentum and jets. A data s le of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider between 2015 and 2018 is used. The data correspond to a total integrated luminosity of 139 fb − 1 . The search is guided by a type-II seesaw model that extends the scalar sector of the Standard Model with a scalar triplet, leading to a phenomenology that includes doubly and singly charged Higgs bosons. Two scenarios are explored, corresponding to the pair production of doubly charged H ±± bosons, or the associated production of a doubly charged H ±± boson and a singly charged H ± boson. No significant deviations from the Standard Model predictions are observed. H ±± bosons are excluded at 95% confidence level up to 350 GeV and 230 GeV for the pair and associated production modes, respectively.
Publisher: Springer Science and Business Media LLC
Date: 06-2021
Abstract: A search for charged Higgs bosons decaying into a top quark and a bottom quark is presented. The data analysed correspond to 139 fb − 1 of proton-proton collisions at $$ \\sqrt{s} $$ s = 13 TeV, recorded with the ATLAS detector at the LHC. The production of a heavy charged Higgs boson in association with a top quark and a bottom quark, pp → tbH + → tbtb , is explored in the H + mass range from 200 to 2000 GeV using final states with jets and one electron or muon. Events are categorised according to the multiplicity of jets and b -tagged jets, and multivariate analysis techniques are used to discriminate between signal and background events. No significant excess above the background-only hypothesis is observed and exclusion limits are derived for the production cross-section times branching ratio of a charged Higgs boson as a function of its mass they range from 3.6 pb at 200 GeV to 0.036 pb at 2000 GeV at 95% confidence level. The results are interpreted in the hMSSM and $$ {M}_h^{125} $$ M h 125 scenarios.
Publisher: Elsevier BV
Date: 04-2015
Publisher: Elsevier BV
Date: 09-2018
Publisher: Trans Tech Publications, Ltd.
Date: 04-2008
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.575-578.1246
Abstract: On the basis of suitable arrangement for the special stress surrounding and parameters selection, Realistic Failure Process Analysis 2-D (RFPA2D) numerical simulation of extra-thick coal seams’ displacement and failure is carried out. It’s proved that the numerical simulation results are consistent with the in-sit measurement results of top coal’s advance supporting stress and deep-hole displacement. So application of RFPA2D in sub-level caving mining extra-thick coal seams is reliable. It’s also proved that application of RFPA2D in sub-level caving mining can do great help to study the nature of top coal’s displacement, fragmentation and failure process of extra-thick coal seams. As the top coal’s displacement and failure situation under certain circumstance can be forecasted by RFPA2D numerical simulation, the most suitable top coal thickness under certain circumstance can be predicted by RFPA2D numerical simulation test, which can do great benefit to extra-thick coal seams’ safe and high efficient mining.
Publisher: Springer Science and Business Media LLC
Date: 2021
Abstract: Differential cross-sections are measured for top-quark pair production in the all-hadronic decay mode, using proton-proton collision events collected by the ATLAS experiment in which all six decay jets are separately resolved. Absolute and normalised single- and double-differential cross-sections are measured at particle and parton level as a function of various kinematic variables. Emphasis is placed on well-measured observables in fully reconstructed final states, as well as on the study of correlations between the top-quark pair system and additional jet radiation identified in the event. The study is performed using data from proton-proton collisions at $$ \\sqrt{s} $$ s = 13 TeV collected by the ATLAS detector at CERN’s Large Hadron Collider in 2015 and 2016, corresponding to an integrated luminosity of 36.1 fb − 1 . The rapidities of the in idual top quarks and of the top-quark pair are well modelled by several independent event generators. Significant mismodelling is observed in the transverse momenta of the leading three jet emissions, while the leading top-quark transverse momentum and top-quark pair transverse momentum are both found to be incompatible with several theoretical predictions.
Publisher: Springer Science and Business Media LLC
Date: 11-2020
Abstract: In this paper, a new technique for reconstructing and identifying hadronically decaying τ + τ − pairs with a large Lorentz boost, referred to as the di- τ tagger, is developed and used for the first time in the ATLAS experiment at the Large Hadron Collider. A benchmark di- τ tagging selection is employed in the search for resonant Higgs boson pair production, where one Higgs boson decays into a boosted $$ b\\overline{b} $$ b b ¯ pair and the other into a boosted τ + τ − pair, with two hadronically decaying τ -leptons in the final state. Using 139 fb − 1 of proton-proton collision data recorded at a centre-of-mass energy of 13 TeV, the efficiency of the di- τ tagger is determined and the background with quark- or gluon-initiated jets misidentified as di- τ objects is estimated. The search for a heavy, narrow, scalar resonance produced via gluon-gluon fusion and decaying into two Higgs bosons is carried out in the mass range 1–3 TeV using the same dataset. No deviations from the Standard Model predictions are observed, and 95% confidence-level exclusion limits are set on this model.
Publisher: Elsevier BV
Date: 11-2020
Publisher: Springer Science and Business Media LLC
Date: 28-06-2021
Publisher: American Physical Society (APS)
Date: 22-05-2006
Publisher: Elsevier BV
Date: 08-2015
Publisher: Trans Tech Publications, Ltd.
Date: 04-2008
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.575-578.886
Abstract: A coupled thermo-mechanical model is employed to analyze the thermo-mechanical behavior of a widely used laminated composite subject to temperature decrease at service conditions. Three sets of governing equations, i.e. heat transfer, thermo-mechanical deformation and damage evolution are respectively described in the model. These equations are then assembled into a coupled matrix equation using finite element formulation and then solved simultaneously at each time interval. A numerical model of two layered composites with some preexisting equal-spacing cracks along the interface in the lower layer is set up to investigate the thermal induced crack propagation due to temperature decrease. Results are presented in the form of crack propagation process in stress profiles and discussed. Numerical simulations show that the crack propagation behavior of the composites is closely dependent on the physico-mechanical properties of two layers and preexisting cracks. It is found that thermal induced cracks penetrate into the upper layer and grow in the upper layer due to the low strength of the upper layer when the model is subject to uniform temperature decrease.
Publisher: Elsevier BV
Date: 09-2021
Publisher: Springer Science and Business Media LLC
Date: 07-2020
Abstract: This paper presents a measurement of the production cross-section of a Z boson in association with b -jets, in proton-proton collisions at $$ \sqrt{s} $$ s = 13 TeV with the ATLAS experiment at the Large Hadron Collider using data corresponding to an integrated luminosity of 35.6 fb − 1 . Inclusive and differential cross-sections are measured for events containing a Z boson decaying into electrons or muons and produced in association with at least one or at least two b -jets with transverse momentum p T 20 GeV and rapidity |y| 2 . 5. Predictions from several Monte Carlo generators based on leading-order (LO) or next-to-leading-order (NLO) matrix elements interfaced with a parton-shower simulation and testing different flavour schemes for the choice of initial-state partons are compared with measured cross-sections. The 5-flavour number scheme predictions at NLO accuracy agree better with data than 4-flavour number scheme ones. The 4-flavour number scheme predictions underestimate data in events with at least one b-jet.
Publisher: Springer Science and Business Media LLC
Date: 30-08-2023
Publisher: Informa UK Limited
Date: 2020
Publisher: Springer Science and Business Media LLC
Date: 10-2020
Abstract: This paper presents a search for new heavy particles decaying into a pair of top quarks using 139 fb − 1 of proton-proton collision data recorded at a centre-of-mass energy of $$ \\sqrt{s} $$ s = 13 TeV with the ATLAS detector at the Large Hadron Collider. The search is performed using events consistent with pair production of high-transverse-momentum top quarks and their subsequent decays into the fully hadronic final states. The analysis is optimized for resonances decaying into a $$ t\\overline{t} $$ t t ¯ pair with mass above 1.4 TeV, exploiting a dedicated multivariate technique with jet substructure to identify hadronically decaying top quarks using large-radius jets and evaluating the background expectation from data. No significant deviation from the background prediction is observed. Limits are set on the production cross-section times branching fraction for the new Z ′ boson in a topcolor-assisted-technicolor model. The Z ′ boson masses below 3.9 and 4.7 TeV are excluded at 95% confidence level for the decay widths of 1% and 3%, respectively.
Publisher: Springer Science and Business Media LLC
Date: 03-2021
DOI: 10.1140/EPJC/S10052-021-08929-9
Abstract: A search for the pair production of heavy leptons as predicted by the type-III seesaw mechanism is presented. The search uses proton–proton collision data at a centre-of-mass energy of 13 TeV, corresponding to $$ 139\\,{\\text {fb}}^{-1} $$ 139 fb - 1 of integrated luminosity recorded by the ATLAS detector during Run 2 of the Large Hadron Collider. The analysis focuses on the final state with two light leptons (electrons or muons) of different flavour and charge combinations, with at least two jets and large missing transverse momentum. No significant excess over the Standard Model expectation is observed. The results are translated into exclusion limits on heavy-lepton masses, and the observed lower limit on the mass of the type-III seesaw heavy leptons is 790 GeV at 95% confidence level.
Publisher: Springer Science and Business Media LLC
Date: 26-05-2013
Publisher: Trans Tech Publications, Ltd.
Date: 09-2013
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.405-408.402
Abstract: Based on the fluid-solid coupling theory, we study the stability of surrounding rock mass around underground oil storage in Huangdao, Shandong province, analyze the stress of the surrounding rock mass around three chambers and the displacement change of several key monitoring points after excavation and evaluate the stability of surrounding rock mass using COMSOL Multiphysics software. Research results show that the stress at both sides of the straight wall of cavern increases, especially obvious stress concentration forms at the corners of the cavern, and the surrounding rock mass moves towards the cavern after excavation. The stress and displacement of the surrounding rock mass will increase accordingly after setting the water curtains, but the change does not have a substantive impact on the stability of surrounding rock mass.
Publisher: Elsevier BV
Date: 05-2004
Publisher: Springer Science and Business Media LLC
Date: 08-2020
DOI: 10.1140/EPJC/S10052-020-8181-6
Abstract: A measurement of observables sensitive to spin correlations in $$t\\bar{t}$$ t t ¯ production is presented, using 36.1 $$\\hbox {fb}^{-1}$$ fb - 1 of pp collision data at $$\\sqrt{s} = 13$$ s = 13 TeV recorded with the ATLAS detector at the Large Hadron Collider. Differential cross-sections are measured in events with exactly one electron and one muon with opposite-sign electric charge as a function of the azimuthal opening angle and the absolute difference in pseudorapidity between the electron and muon candidates in the laboratory frame. The azimuthal opening angle is also measured as a function of the invariant mass of the $$t\\bar{t}$$ t t ¯ system. The measured differential cross-sections are compared to predictions by several NLO Monte Carlo generators and fixed-order calculations. The observed degree of spin correlation is somewhat higher than predicted by the generators used. The data are consistent with the prediction of one of the fixed-order calculations at NLO, but agree less well with higher-order predictions. Using these leptonic observables, a search is performed for pair production of supersymmetric top squarks decaying into Standard Model top quarks and light neutralinos. Top squark masses between 170 and 230 GeV are largely excluded at the 95% confidence level for kinematically allowed values of the neutralino mass.
Publisher: Springer Science and Business Media LLC
Date: 07-2021
Abstract: Measurements of four-lepton differential and integrated fiducial cross-sections in events with two same-flavour, opposite-charge electron or muon pairs are presented. The data correspond to 139 fb − 1 of $$ \\sqrt{s} $$ s = 13 TeV proton-proton collisions, collected by the ATLAS detector during Run 2 of the Large Hadron Collider (2015–2018). The final state has contributions from a number of interesting Standard Model processes that dominate in different four-lepton invariant mass regions, including single Z boson production, Higgs boson production and on-shell ZZ production, with a complex mix of interference terms, and possible contributions from physics beyond the Standard Model. The differential cross-sections include the four-lepton invariant mass inclusively, in slices of other kinematic variables, and in different lepton flavour categories. Also measured are dilepton invariant masses, transverse momenta, and angular correlation variables, in four regions of four-lepton invariant mass, each dominated by different processes. The measurements are corrected for detector effects and are compared with state-of-the-art Standard Model calculations, which are found to be consistent with the data. The Z → 4 ℓ branching fraction is extracted, giving a value of (4 . 41 ± 0 . 30) × 10 − 6 . Constraints on effective field theory parameters and a model based on a spontaneously broken B − L gauge symmetry are also evaluated. Further reinterpretations can be performed with the provided information.
Publisher: Springer Science and Business Media LLC
Date: 12-2020
DOI: 10.1140/EPJC/S10052-020-08554-Y
Abstract: This paper reports on a search for heavy resonances decaying into WW , ZZ or WZ using proton–proton collision data at a centre-of-mass energy of $$\\sqrt{s}=13$$ s = 13 TeV. The data, corresponding to an integrated luminosity of 139 $$\\mathrm{fb}^{1}$$ fb 1 , were recorded with the ATLAS detector from 2015 to 2018 at the Large Hadron Collider. The search is performed for final states in which one W or Z boson decays leptonically, and the other W boson or Z boson decays hadronically. The data are found to be described well by expected backgrounds. Upper bounds on the production cross sections of heavy scalar, vector or tensor resonances are derived in the mass range 300–5000 GeV within the context of Standard Model extensions with warped extra dimensions or including a heavy vector triplet. Production through gluon–gluon fusion, Drell–Yan or vector-boson fusion are considered, depending on the assumed model.
Publisher: MDPI AG
Date: 09-09-2021
Abstract: When graduates of Australian social work courses embark on a career in mental health, the systems they enter are complex, fragmented and evolving. Emerging practitioners will commonly be confronted by the loneliness, social exclusion, poverty and prejudice experienced by people living with mental distress however, social work practice may not be focused on these factors. Instead, in accordance with the dominant biomedical perspective, symptom and risk management may predominate. Frustration with the limitations evident in this approach has seen the United Nations call for the transformation of mental health service delivery. Recognising paradigmatic influences on mental health social work may lead to a more considered enactment of person centred, recovery and rights-based approaches. This paper compares and contrasts influences of neo-liberalism, critical theory, human rights and post-structuralism on mental health social work practice. In preparing social work practitioners to recognise the influence of, and work more creatively with, intersecting paradigms, social work educators strive to foster a transformative approach to mental health practice that straddles discourses.
Publisher: Trans Tech Publications, Ltd.
Date: 12-2010
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.163-167.1819
Abstract: The dynamic compressive experiments of cubic concrete specimens under various biaxial equal proportion loading were preformed. The biaxial equal proportion stress in the tests were kept constant at 1:0, 1:0.5 and 1:1, respectively, and the tested strain rate ranged from 10−5/s to 10−2/s. Based on the experimental results, the influence of the strain rates on compressive characteristics of concrete under various biaxial stress ratios were researched. The unified strength criterion in terms of principal stress space considering the influence of strain rates and biaxial stress ratio is proposed. The fitting curves by the present strength criterion agree well with experimental data.
Publisher: Trans Tech Publications, Ltd.
Date: 04-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.919-921.747
Abstract: In this paper, the stress and strain distribution in coal seam and fault edge under various fault dips is numerically simulated to study the stability of the barrier pillar and determine the reasonable length of coal seam mining using COMSOL Multiphysics package. Numerical simulations show that remarkable increase in stress around fault edge when coal seam is about 250 m away from the fault with a smaller fault angle and the stability of fault is seriously affected by the mining excavation. While the obvious increase in stress around fault edge can be observed until coal seam is about 200 m or 150 m away from the fault with a larger fault angle and the stability of fault is seriously affected by mining excavation. Numerical results indicate that the larger the fault dip is, the larger the reasonable mining length in coal seam where a fault near coal seam exists. Moreover, the fault with smaller dip is more easily activated to induce the failure of the fault and the occurrence of water inrush in coal mining. To prevent the occurrence of fault failure accident, we need to study the reasonable mining length of coal seam, to ensure the safety production and increase the recovery ratio of coal.
Publisher: Elsevier BV
Date: 04-2004
Publisher: Trans Tech Publications, Ltd.
Date: 11-2006
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.324-325.931
Abstract: Ductile tearing of brittle solid with initial crack is studied numerically. This work is focused on the simulation and analysis of crack path deviation for the respective configuration and the study of relation between crack length and the fracture resistance, and that the configuration of fracture surface is also observed. The simulating tool is a novel numerical code, 3D Realistic Failure Process Analysis code (abbreviated as RFPA3D). The simulating investigation has shown that the fracture resistance decreases with the increase of the angle between the crack ends and horizontal direction. Due to heterogeneity of materials distribution, crack path deviation towards the softer zone or elements is observed. The topography of the non-planar fracture surface has plotted. Concluding the simulation made in the present study, the problem of crack extension in the brittle solid can be handled by RFPA3D. Fracture resistance can be predicted and the crack path deviation be simulated, if the model parameters have been carefully identified and the mesh design is adequate. So this work is beneficial to choose safe load-spots and predicate the direction of the crack path deviation.
Publisher: Springer Science and Business Media LLC
Date: 19-05-2016
Publisher: Springer Science and Business Media LLC
Date: 12-2020
DOI: 10.1140/EPJC/S10052-020-08477-8
Abstract: The jet energy scale, jet energy resolution, and their systematic uncertainties are measured for jets reconstructed with the ATLAS detector in 2012 using proton–proton data produced at a centre-of-mass energy of 8 TeV with an integrated luminosity of $$20 \\, \\hbox {fb}^{-1}$$ 20 fb - 1 . Jets are reconstructed from clusters of energy depositions in the ATLAS calorimeters using the anti- $$k_t$$ k t algorithm. A jet calibration scheme is applied in multiple steps, each addressing specific effects including mitigation of contributions from additional proton–proton collisions, loss of energy in dead material, calorimeter non-compensation, angular biases and other global jet effects. The final calibration step uses several in situ techniques and corrects for residual effects not captured by the initial calibration. These analyses measure both the jet energy scale and resolution by exploiting the transverse momentum balance in $$\\gamma $$ γ + jet, Z + jet, dijet, and multijet events. A statistical combination of these measurements is performed. In the central detector region, the derived calibration has a precision better than 1% for jets with transverse momentum $$150 \\, \\hbox {GeV} p_{{\\mathrm {T}}} $$ 150 GeV p T 1500 GeV, and the relative energy resolution is $$(8.4\\pm 0.6)\\%$$ ( 8.4 ± 0.6 ) % for $$p_{{\\mathrm {T}}}= 100 \\, \\hbox {GeV}$$ p T = 100 GeV and $$(23\\pm 2)\\%$$ ( 23 ± 2 ) % for $$p_{{\\mathrm {T}}}= 20 \\, \\hbox {GeV}$$ p T = 20 GeV . The calibration scheme for jets with radius parameter $$R=1.0$$ R = 1.0 , for which jets receive a dedicated calibration of the jet mass, is also discussed.
Publisher: Elsevier BV
Date: 06-2011
Publisher: Hindawi Limited
Date: 15-11-2018
DOI: 10.1155/2018/6863925
Abstract: Sudden inelastic deformations in rock are associated with acoustic emission (AE). Therefore, AE monitoring technique can be used to study the fracture processes of rock. In this paper, AE tests were conducted on the granitic gneiss specimens under the uniaxial compressive loading conditions. The temporal changes in AE hit parameters and spatial-temporal evolution of AE events during the failure process of the granitic gneiss specimens were studied, and several characteristic AE phenomena (i.e., dramatic increase in dominant frequency, AE energy, and hit rate, the AE event with a high energy level, and the through-going distribution of the AE events with intermediate energy levels) were statistically analyzed before the failure occurred. It was found that the chronological order of the characteristic AE phenomena was relatively certain and correspondingly had a close relationship with the crack development stage. Because of the difference of the stress level at each crack development stage, the stability at different crack development stages is different. Therefore, a rock stability assessment approach was established based on the chronological order of the characteristic AE phenomena, and then the rock stability was assessed using the proposed approach.
Publisher: Springer Science and Business Media LLC
Date: 08-2020
DOI: 10.1140/EPJC/S10052-020-8050-3
Abstract: The results of a search for electroweakino pair production $$pp \\rightarrow \\tilde{\\chi }^\\pm _1 \\tilde{\\chi }^0_2$$ p p → χ ~ 1 ± χ ~ 2 0 in which the chargino ( $$\\tilde{\\chi }^\\pm _1$$ χ ~ 1 ± ) decays into a W boson and the lightest neutralino ( $$\\tilde{\\chi }^0_1$$ χ ~ 1 0 ), while the heavier neutralino ( $$\\tilde{\\chi }^0_2$$ χ ~ 2 0 ) decays into the Standard Model 125 GeV Higgs boson and a second $$\\tilde{\\chi }^0_1$$ χ ~ 1 0 are presented. The signal selection requires a pair of b -tagged jets consistent with those from a Higgs boson decay, and either an electron or a muon from the W boson decay, together with missing transverse momentum from the corresponding neutrino and the stable neutralinos. The analysis is based on data corresponding to 139 $$\\mathrm {fb}^{-1}$$ fb - 1 of $$\\sqrt{s}=13$$ s = 13 TeV pp collisions provided by the Large Hadron Collider and recorded by the ATLAS detector. No statistically significant evidence of an excess of events above the Standard Model expectation is found. Limits are set on the direct production of the electroweakinos in simplified models, assuming pure wino cross-sections. Masses of $$\\tilde{\\chi }^{\\pm }_{1}/\\tilde{\\chi }^{0}_{2}$$ χ ~ 1 ± / χ ~ 2 0 up to 740 GeV are excluded at 95% confidence level for a massless $$\\tilde{\\chi }^{0}_{1}$$ χ ~ 1 0 .
Publisher: Springer Science and Business Media LLC
Date: 10-2020
DOI: 10.1140/EPJC/S10052-020-8223-0
Abstract: Inclusive and differential fiducial cross sections of the Higgs boson are measured in the $$H \\rightarrow ZZ^{*} \\rightarrow 4\\ell $$ H → Z Z ∗ → 4 ℓ ( $$\\ell = e,\\mu $$ ℓ = e , μ ) decay channel. The results are based on proton-proton collision data produced at the Large Hadron Collider at a centre-of-mass energy of 13 TeV and recorded by the ATLAS detector from 2015 to 2018, equivalent to an integrated luminosity of 139 $$\\hbox {fb}^{-1}$$ fb - 1 . The inclusive fiducial cross section for the $$H \\rightarrow ZZ^{*} \\rightarrow 4\\ell $$ H → Z Z ∗ → 4 ℓ process is measured to be $$\\sigma _\\mathrm {fid} = 3.28 \\,{\\pm }\\, 0.32$$ σ fid = 3.28 ± 0.32 fb, in agreement with the Standard Model prediction of $$\\sigma _\\mathrm {fid, SM} = 3.41 \\pm 0.18 $$ σ fid , SM = 3.41 ± 0.18 fb. Differential fiducial cross sections are measured for a variety of observables which are sensitive to the production and decay of the Higgs boson. All measurements are in agreement with the Standard Model predictions. The results are used to constrain anomalous Higgs boson interactions with Standard Model particles.
Publisher: Springer Science and Business Media LLC
Date: 02-2018
Publisher: MDPI AG
Date: 29-05-2018
DOI: 10.3390/MIN8060231
Publisher: American Physical Society (APS)
Date: 24-03-2021
Publisher: Elsevier BV
Date: 09-2006
Publisher: Springer Science and Business Media LLC
Date: 07-2020
DOI: 10.1140/EPJC/S10052-020-8001-Z
Abstract: This paper describes precision measurements of the transverse momentum $$p_\\mathrm {T}^{\\ell \\ell }$$ p T ℓ ℓ ( $$\\ell =e,\\mu $$ ℓ = e , μ ) and of the angular variable $$\\phi ^{*}_{\\eta }$$ ϕ η ∗ distributions of Drell–Yan lepton pairs in a mass range of 66–116 GeV. The analysis uses data from 36.1 fb $$^{-1}$$ - 1 of proton–proton collisions at a centre-of-mass energy of $$\\sqrt{s}=13\\,$$ s = 13 TeV collected by the ATLAS experiment at the LHC in 2015 and 2016. Measurements in electron-pair and muon-pair final states are performed in the same fiducial volumes, corrected for detector effects, and combined. Compared to previous measurements in proton–proton collisions at $$\\sqrt{s}=7$$ s = 7 and $$8\\,$$ 8 TeV, these new measurements probe perturbative QCD at a higher centre-of-mass energy with a different composition of initial states. They reach a precision of 0.2 $$\\%$$ % for the normalized spectra at low values of $$p_\\mathrm {T}^{\\ell \\ell }$$ p T ℓ ℓ . The data are compared with different QCD predictions, where it is found that predictions based on resummation approaches can describe the full spectrum within uncertainties.
Publisher: Springer Science and Business Media LLC
Date: 10-2020
DOI: 10.1140/EPJC/S10052-020-8227-9
Abstract: Higgs boson properties are studied in the four-lepton decay channel (where lepton = e , $$\\mu $$ μ ) using 139 $$\\hbox {fb}^{-1}$$ fb - 1 of proton–proton collision data recorded at $$\\sqrt{s}=$$ s = 13 TeV by the ATLAS experiment at the Large Hadron Collider. The inclusive cross-section times branching ratio for $$H\\rightarrow ZZ^*$$ H → Z Z ∗ decay is measured to be $$1.34 \\pm 0.12$$ 1.34 ± 0.12 pb for a Higgs boson with absolute rapidity below 2.5, in good agreement with the Standard Model prediction of $$1.33 \\pm 0.08$$ 1.33 ± 0.08 pb. Cross-sections times branching ratio are measured for the main Higgs boson production modes in several exclusive phase-space regions. The measurements are interpreted in terms of coupling modifiers and of the tensor structure of Higgs boson interactions using an effective field theory approach. Exclusion limits are set on the CP-even and CP-odd ‘beyond the Standard Model’ couplings of the Higgs boson to vector bosons, gluons and top quarks.
Publisher: Elsevier BV
Date: 10-2016
Publisher: Trans Tech Publications, Ltd.
Date: 11-2006
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.324-325.51
Abstract: The phenomenon creep fracture is well-known for concrete. In the present paper, the Material Failure Process Analysis (MFPA2D) model for concrete in the failure process is coupled in series with the time-dependence of the concrete damage and deformation. Further, the progressive creep failure of concrete specimens under constant tensile loading was numerically simulated and the typical time-dependent deformations: the transient creep, the steady-state creep and the accelerating creep were also represented. The numerical simulations indicate that the macroscopic creep failure is induced by clusters of micro-fractures on a mesocopic scale. The above numerical results offer us some theoretical indications and instructions to further investigate the instability failure mechanisms of engineering concrete structures in civil and hydraulic engineering.
Publisher: American Physical Society (APS)
Date: 21-09-2020
Publisher: Elsevier BV
Date: 09-2023
Publisher: Elsevier BV
Date: 10-2015
Publisher: Springer Science and Business Media LLC
Date: 30-08-2014
Publisher: Trans Tech Publications, Ltd.
Date: 02-2011
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.50-51.929
Abstract: Spallation of concrete under dynamic loading has been the hot issue of concern about civil engineering structures and protective engineering. In the present paper, the principle of propagation of stress wave and the induced spallation process along a one-dimensional bar and the RFPA-Dynamics code which considers the heterogeneity of the concrete materials are briefly introduced. In order to numerically investigate the effect of mesh size of numerical model on the computational results, the failure process of concrete with three mesh sizes under dynamic loads was numerically simulated using RFPA-Dynamics code. Numerical simulations show that the failure patterns of concrete with different mesh sizes under dynamic stress waves are different. It is found that for the numerical models with the same mechanical parameters, the smaller mesh size of the numerical model is, the longer propagation of stress wave delay, the smaller the compressive stress is, thus the greater the tensile stress is, and the number of cracks is increasing, in general, rupture is more serious. The accuracy of mesh is little to improve when the number of the grid increases to a certain value.
Publisher: American Physical Society (APS)
Date: 27-07-2021
Publisher: Springer Science and Business Media LLC
Date: 08-2020
DOI: 10.1140/EPJC/S10052-020-8102-8
Abstract: A search for direct pair production of scalar partners of the top quark (top squarks or scalar third-generation up-type leptoquarks) in the all-hadronic $$t{\\bar{t}}$$ t t ¯ plus missing transverse momentum final state is presented. The analysis of 139 $$\\hbox {fb}^{-1}$$ fb - 1 of $${\\sqrt{s}=13}$$ s = 13 TeV proton–proton collision data collected using the ATLAS detector at the LHC yields no significant excess over the Standard Model background expectation. To interpret the results, a supersymmetric model is used where the top squark decays via $${\\tilde{t}} \\rightarrow t^{(*)} {\\tilde{\\chi }}^0_1$$ t ~ → t ( ∗ ) χ ~ 1 0 , with $$t^{(*)}$$ t ( ∗ ) denoting an on-shell (off-shell) top quark and $${\\tilde{\\chi }}^0_1$$ χ ~ 1 0 the lightest neutralino. Three specific event selections are optimised for the following scenarios. In the scenario where $$m_{{\\tilde{t}}} m_t+m_{{\\tilde{\\chi }}^0_1}$$ m t ~ m t + m χ ~ 1 0 , top squark masses are excluded in the range 400–1250 GeV for $${\\tilde{\\chi }}^0_1$$ χ ~ 1 0 masses below 200 GeV at 95% confidence level. In the situation where $$m_{{\\tilde{t}}}\\sim m_t+m_{{\\tilde{\\chi }}^0_1}$$ m t ~ ∼ m t + m χ ~ 1 0 , top squark masses in the range 300–630 GeV are excluded, while in the case where $$m_{{\\tilde{t}}} m_W+m_b+m_{{\\tilde{\\chi }}^0_1}$$ m t ~ m W + m b + m χ ~ 1 0 (with $$m_{{\\tilde{t}}}-m_{{\\tilde{\\chi }}^0_1}\\ge 5$$ m t ~ - m χ ~ 1 0 ≥ 5 GeV), considered for the first time in an ATLAS all-hadronic search, top squark masses in the range 300–660 GeV are excluded. Limits are also set for scalar third-generation up-type leptoquarks, excluding leptoquarks with masses below 1240 GeV when considering only leptoquark decays into a top quark and a neutrino.
Publisher: Springer Science and Business Media LLC
Date: 18-02-2014
Publisher: Springer Science and Business Media LLC
Date: 10-2020
Abstract: A search for a chargino-neutralino pair decaying via the 125 GeV Higgs boson into photons is presented. The study is based on the data collected between 2015 and 2018 with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 139 fb − 1 of pp collisions at a centre-of-mass energy of 13 TeV. No significant excess over the expected background is observed. Upper limits at 95% confidence level for a massless $$ {\\tilde{\\chi}}_1^0 $$ χ ˜ 1 0 are set on several electroweakino production cross-sections and the visible cross-section for beyond the Standard Model processes. In the context of simplified supersymmetric models, 95% confidence-level limits of up to 310 GeV in $$ m\\left({\\tilde{\\chi}}_1^{\\pm }/{\\tilde{\\chi}}_2^0\\right) $$ m χ ˜ 1 ± / χ ˜ 2 0 , where $$ m\\left({\\tilde{\\chi}}_1^0\\right) $$ m χ ˜ 1 0 = 0 . 5 GeV, are set. Limits at 95% confidence level are also set on the $$ {\\tilde{\\chi}}_1^{\\pm }{\\tilde{\\chi}}_2^0 $$ χ ˜ 1 ± χ ˜ 2 0 cross-section in the mass plane of $$ m\\left({\\tilde{\\chi}}_1^{\\pm }/{\\tilde{\\chi}}_2^0\\right) $$ m χ ˜ 1 ± / χ ˜ 2 0 and $$ m\\left({\\tilde{\\chi}}_1^0\\right) $$ m χ ˜ 1 0 , and on scenarios with gravitino as the lightest supersymmetric particle. Upper limits at the 95% confidence-level are set on the higgsino production cross-section. Higgsino masses below 380 GeV are excluded for the case of the higgsino fully decaying into a Higgs boson and a gravitino.
Publisher: American Physical Society (APS)
Date: 27-07-2020
Publisher: Trans Tech Publications, Ltd.
Date: 11-2005
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.297-300.2617
Abstract: The purpose of this paper is to investigate shear strength and failure pattern of rock containing two parallel open joints with different horizontal separations using RFPA2D (rock failure process analysis) code. Specimens are placed in a direct shear box. The upper is invariably loaded with normal stress 0.15MPa, the left is controlled by a constant increasing horizontal displacement 0.002mm/step. The whole shear failure process is visually represented and the failure pattern in reasonable accordance with previous experimental results is obtained. In general, only mixed mode (tensile and shear) is observed for the failure pattern in the numerical tests. Tensile cracks initiate from the tips of pre-existing joints respectively with an initiation angle of about 45°, then propagate towards another joint in a single stria Shear cracks occur in the further process and the main direction of shear failure surface is roughly parallel to shear loading. The failure pattern of bridged rock is mainly controlled by the joint separation and the roughness of wavy shear failure surface is different, which is mostly influenced by the joint separation in the same way. The peak shear load, related to the failure patterns, decreases with the increase of joint separation, but the shear strength of intact rock is invariable.
Publisher: American Society of Civil Engineers (ASCE)
Date: 02-2016
Publisher: Trans Tech Publications, Ltd.
Date: 11-2005
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.297-300.2612
Abstract: Rock failure analysis is an important research in investigating the behavior of rocks, especially its failure process. And a rock s le, which contains pre-existing cracks, is a typical s le to investigate the rock failure behavior which under tension or compression, because almost all the natural materials exist micro-flaws more or less. This mode is closed to the natural material character. By using Rock Failure Process Analysis code, RFPA2D, we present a numerical simulation and similar materials experiment on rock s les with two pre-existing cracks in uniaxial compression were conducted to investigate the initiation, propagation, coalescence of cracks and failure mechanism of rock. Numerical simulations visually reproduce the process of crack initiation, propagation and coalescence in rock, which are well tallied with experiments in laboratory.
Publisher: Springer Science and Business Media LLC
Date: 30-10-2021
Abstract: A search for pair production of third-generation scalar leptoquarks decaying into a top quark and a τ -lepton is presented. The search is based on a dataset of pp collisions at $$ \\sqrt{s} $$ s = 13 TeV recorded with the ATLAS detector during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb − 1 . Events are selected if they have one light lepton (electron or muon) and at least one hadronically decaying τ -lepton, or at least two light leptons. In addition, two or more jets, at least one of which must be identified as containing b -hadrons, are required. Six final states, defined by the multiplicity and flavour of lepton candidates, are considered in the analysis. Each of them is split into multiple event categories to simultaneously search for the signal and constrain several leading backgrounds. The signal-rich event categories require at least one hadronically decaying τ -lepton candidate and exploit the presence of energetic final-state objects, which is characteristic of signal events. No significant excess above the Standard Model expectation is observed in any of the considered event categories, and 95% CL upper limits are set on the production cross section as a function of the leptoquark mass, for different assumptions about the branching fractions into tτ and bν . Scalar leptoquarks decaying exclusively into tτ are excluded up to masses of 1 . 43 TeV while, for a branching fraction of 50% into tτ , the lower mass limit is 1 . 22 TeV.
Publisher: Springer Science and Business Media LLC
Date: 07-2021
Abstract: This article presents a new set of proton parton distribution functions, ATLASepWZVjet20, produced in an analysis at next-to-next-to-leading order in QCD. The new data sets considered are the measurements of W + and W − boson and Z boson production in association with jets in pp collisions at $$ \\sqrt{s} $$ s = 8 TeV performed by the ATLAS experiment at the LHC with integrated luminosities of 20 . 2 fb − 1 and 19 . 9 fb − 1 , respectively. The analysis also considers the ATLAS measurements of differential W ± and Z boson production at $$ \\sqrt{s} $$ s = 7 TeV with an integrated luminosity of 4 . 6 fb − 1 and deep-inelastic-scattering data from e ± p collisions at the HERA accelerator. An improved determination of the sea-quark densities at high Bjorken x is shown, while confirming a strange-quark density similar in size to the up- and down-sea-quark densities in the range x ≲ 0 . 02 found by previous ATLAS analyses.
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-7101
Abstract: Fractures in rock are ubiquitous from cold dry planetary bodies to the hottest, wettest climates on Earth, and from km-scale tectonic fractures deep in Earth& #8217 s crust to microcracks in surficial rocks. Yet, many of these fractures propagate progressively over geologic timescales, making their development complex and enigmatic. Therefore, to measure how fractures have developed in rocks exposed at Earth& #8217 s surface over millennia, and how this consequently changes rock physical properties, we collected ten ~25 cm diameter granitic boulders from two sites in the Eastern Sierra, California, USA. The boulders were deposited on the surface of alluvial terraces and fans during geologically instantaneous glacial and alluvial events at different times since about 148ka BP, then the depositional surfaces were subsequently abandoned. The chronosequences of geomorphic surfaces provide a natural laboratory in which rocks of consistent lithology have been exposed to similar environmental conditions for different lengths of time, allowing us to compare rock property evolution on the order of 0 to 105 years of environmental exposure an approach that allows us to better understand and characterize mechanical weathering processes, especially long-term changes in rock fracturing. Note that fresh (time-zero) rocks in this study are represented by boulders found within active channels, and that the measured changes in rocks with longer exposure times are interpreted by comparison with the fresh rocks. Focusing only on similarly sized boulders removes any ambiguities in tectonic and exhumation history that might arise in outcrop s les, thus ensuring that rocks from each site have experienced similar stress conditions namely those restricted to the environment.We performed laboratory measurements on 10 granitic boulders (four from Lundy Canyon, with exposure ages of ~0 to ~148 ka six from Shepherd Creek, with exposure ages of ~0 to ~117 ka) to quantify how rock physical properties changed as a function of environmental exposure age. We measured key parameters commonly used as proxies for crack damage, including porosity, compressional wave velocity (Vp), and shear wave velocity (Vs). We hypothesize that changes in crack damage are likely to affect rock mechanical properties, so we also measured tensile strength, uniaxial compressive strength (UCS), and Young& #8217 s modulus (E). We find that all measured parameters evolve as a function of exposure age, with systematic increases in porosity, and systematic decreases in Vp, Vs, tensile strength, UCS, and E. For ex le, porosity increases from 0.5 & #8211 1.0 % in the fresh rock to 2.6 & #8211 3.2 % in the oldest rocks. We interpret these changes as reflecting progressive subcritical crack growth that arises due to ubiquitous, but relatively low magnitude, environmental stresses continuously acting on the boulders, as opposed to differences inherited before their erosion from bedrock.Apart from demonstrating the importance of environmentally driven cracking in rock weathering, these observations of progressive crack damage accumulation also have significant implications for the interpretation of any measurements made on rocks exposed at Earth& #8217 s surface, even if the age of exposure is relatively short compared to the age of the geologic deposit itself.
Publisher: Springer Science and Business Media LLC
Date: 2021
Abstract: A measurement of event-shape variables in proton-proton collisions at large momentum transfer is presented using data collected at $$ \\sqrt{s} $$ s = 13 TeV with the ATLAS detector at the Large Hadron Collider. Six event-shape variables calculated using hadronic jets are studied in inclusive multijet events using data corresponding to an integrated luminosity of 139 fb − 1 . Measurements are performed in bins of jet multiplicity and in different ranges of the scalar sum of the transverse momenta of the two leading jets, reaching scales beyond 2 TeV. These measurements are compared with predictions from Monte Carlo event generators containing leading-order or next-to-leading order matrix elements matched to parton showers simulated to leading-logarithm accuracy. At low jet multiplicities, shape discrepancies between the measurements and the Monte Carlo predictions are observed. At high jet multiplicities, the shapes are better described but discrepancies in the normalisation are observed.
Publisher: Springer Science and Business Media LLC
Date: 02-06-2023
Publisher: Springer Science and Business Media LLC
Date: 13-08-2020
Publisher: Trans Tech Publications, Ltd.
Date: 12-2013
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.477-478.577
Abstract: The mechanical properties of rock experiencing the variation of joint orientation under uniaxial compression condition were simulated in this paper. Numerical simulations on rock s le in uniaxial compression have been conducted to evaluate the effects of joint orientation on the overall mechanical behaviour of jointed rock masses. It was done using the Rock Failure Process Analysis program RFPA 2D . Numerically simulated stress-strain curve, peak stress, peak strain and failure patterns were compared with the corresponding physical tests. Numerical simulations agree well with physical results, it is shown that RFPA 2D is suitable for the analysis of joint orientation effect on rock fracture.
Publisher: Springer Science and Business Media LLC
Date: 22-10-2021
Publisher: Springer Science and Business Media LLC
Date: 09-2020
Abstract: Inclusive and differential cross-sections for the production of top quarks in association with a photon are measured with proton-proton collision data corresponding to an integrated luminosity of 139 fb − 1 . The data were collected by the ATLAS detector at the LHC during Run 2 between 2015 and 2018 at a centre-of-mass energy of 13 TeV. The measurements are performed in a fiducial volume defined at parton level. Events with exactly one photon, one electron and one muon of opposite sign, and at least two jets, of which at least one is b -tagged, are selected. The fiducial cross-section is measured to be $$ {39.6}_{-2.3}^{+2.7} $$ 39.6 − 2.3 + 2.7 fb. Differential cross-sections as functions of several observables are compared with state-of-the-art Monte Carlo simulations and next-to-leading-order theoretical calculations. These include cross-sections as functions of photon kinematic variables, angular variables related to the photon and the leptons, and angular separations between the two leptons in the event. All measurements are in agreement with the predictions from the Standard Model.
Publisher: Elsevier BV
Date: 09-0009
Publisher: Springer Science and Business Media LLC
Date: 17-03-2022
Publisher: Trans Tech Publications, Ltd.
Date: 11-2005
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.297-300.1113
Abstract: A newly developed numerical code MFPA3D is applied to simulate the progressive damage and failure process of laminated cylindrical composite shell. Heterogeneities in meso-scale are taken into account by randomly distributing the material properties throughout the model by following a Weibull statistical distribution. The cylindrical composite shell is discretized into 3-D block elements with the fixed size and is subjected to a lateral compressive loading, applied with a constant displacement control manner. The numerical simulation results show that not only the process of crack initiation, propagation and coalescence but also the failure process can be numerically obtained in three dimensional. The MFPA3D modeling demonstrates that the code can simulate non-linear behavior of brittle materials with a simple mesoscopic constitutive law with a strength and elastic modulus reduction of the weaken elements.
Publisher: American Physical Society (APS)
Date: 10-06-2021
Publisher: Trans Tech Publications, Ltd.
Date: 05-2013
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.690-693.1737
Abstract: The mechanical properties of granite experiencing high temperatures under uniaxial compression condition were simulated in this paper. Numerically simulated stress-strain curve, peak stress, peak strain and the tangent elastic modulus were compared with the corresponding physical tests. Simulated results agree well with physical tests results, it is shown that Abaqus is suitable for the analysis of the temperature effect on rock fracture.
Publisher: American Physical Society (APS)
Date: 04-06-2020
Publisher: Springer Science and Business Media LLC
Date: 02-2021
DOI: 10.1140/EPJC/S10052-020-08734-W
Abstract: Differential cross-section measurements are presented for the electroweak production of two jets in association with a Z boson. These measurements are sensitive to the vector-boson fusion production mechanism and provide a fundamental test of the gauge structure of the Standard Model. The analysis is performed using proton–proton collision data collected by ATLAS at $$\\sqrt{s}=13\\ \\hbox {TeV}$$ s = 13 TeV and with an integrated luminosity of $$139\\ \\hbox {fb}^{-1}$$ 139 fb - 1 . The differential cross-sections are measured in the $$Z\\rightarrow \\ell ^+\\ell ^-$$ Z → ℓ + ℓ - decay channel ( $$\\ell =e,\\mu $$ ℓ = e , μ ) as a function of four observables: the dijet invariant mass, the rapidity interval spanned by the two jets, the signed azimuthal angle between the two jets, and the transverse momentum of the dilepton pair. The data are corrected for the effects of detector inefficiency and resolution and are sufficiently precise to distinguish between different state-of-the-art theoretical predictions calculated using Powheg+Pythia8 , Herwig7+Vbfnlo and Sherpa 2.2. The differential cross-sections are used to search for anomalous weak-boson self-interactions using a dimension-six effective field theory. The measurement of the signed azimuthal angle between the two jets is found to be particularly sensitive to the interference between the Standard Model and dimension-six scattering litudes and provides a direct test of charge-conjugation and parity invariance in the weak-boson self-interactions.
Publisher: Elsevier BV
Date: 10-2021
Publisher: Springer Science and Business Media LLC
Date: 11-2017
Publisher: Trans Tech Publications, Ltd.
Date: 11-2005
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.297-300.1196
Abstract: This paper introduces a newly developed three-dimensional Material Failure Process Analysis code, MFPA3D to model the failure processes of brittle materials, such as concrete, ceramics, fibrous materials, and rocks. This numerical code, based on a stress analysis method (finite element method) and a material failure constitutive law, can be taken as a tool in numerical modeling analysis to enhance our understanding of the failure mechanisms of brittle materials. Properties of material heterogeneity are taken into account. The material is discretized into numerous small elements with fixed size. Fracture behavior can be modeled by reducing the material stiffness and strength after the peak strength of the material has been reached. The evolution of the cracking process down to full fracture implies strain softening, which describes the post-peak gradual decline of stress at increasing strain. In the present study, a Mohr-Coulomb criterion envelop with a tension cut-off is used so that the element may fail either in shear or in tension. Simulated fracture or crack patterns of two ex les are found quite realistic, and the results strongly depend on the heterogeneity level.
Publisher: American Physical Society (APS)
Date: 07-06-2021
Publisher: Springer Science and Business Media LLC
Date: 08-2021
DOI: 10.1140/EPJC/S10052-021-09402-3
Abstract: Jet energy scale and resolution measurements with their associated uncertainties are reported for jets using 36–81 fb $$^{-1}$$ - 1 of proton–proton collision data with a centre-of-mass energy of $$\sqrt{s}=13$$ s = 13 $${\text {Te}}{\text {V}}$$ TeV collected by the ATLAS detector at the LHC. Jets are reconstructed using two different input types: topo-clusters formed from energy deposits in calorimeter cells, as well as an algorithmic combination of charged-particle tracks with those topo-clusters, referred to as the ATLAS particle-flow reconstruction method. The anti- $$k_t$$ k t jet algorithm with radius parameter $$R=0.4$$ R = 0.4 is the primary jet definition used for both jet types. This result presents new jet energy scale and resolution measurements in the high pile-up conditions of late LHC Run 2 as well as a full calibration of particle-flow jets in ATLAS. Jets are initially calibrated using a sequence of simulation-based corrections. Next, several in situ techniques are employed to correct for differences between data and simulation and to measure the resolution of jets. The systematic uncertainties in the jet energy scale for central jets ( $$|\eta | .2$$ | η | 1.2 ) vary from 1% for a wide range of high- $$p_{{\text {T}}}$$ p T jets ( $$250 _{{\text {T}}} ~{\text {Ge}}{\text {V}}$$ 250 p T 2000 GeV ), to 5% at very low $$p_{{\text {T}}}$$ p T ( $$20~{\text {Ge}}{\text {V}}$$ 20 GeV ) and 3.5% at very high $$p_{{\text {T}}}$$ p T ( $$ .5~{\text {Te}}{\text {V}}$$ 2.5 TeV ). The relative jet energy resolution is measured and ranges from ( $$24 \pm 1.5$$ 24 ± 1.5 )% at 20 $${\text {Ge}}{\text {V}}$$ GeV to ( $$6 \pm 0.5$$ 6 ± 0.5 )% at 300 $${\text {Ge}}{\text {V}}$$ GeV .
Publisher: Springer Science and Business Media LLC
Date: 08-2020
Abstract: The combination of measurements of the W boson polarization in top quark decays performed by the ATLAS and CMS collaborations is presented. The measurements are based on proton-proton collision data produced at the LHC at a centre-of-mass energy of 8 TeV, and corresponding to an integrated luminosity of about 20 fb − 1 for each experiment. The measurements used events containing one lepton and having different jet multiplicities in the final state. The results are quoted as fractions of W bosons with longitudinal ( F 0 ), left-handed ( F L ), or right-handed ( F R ) polarizations. The resulting combined measurements of the polarization fractions are F 0 = 0 . 693 ± 0 . 014 and F L = 0 . 315 ± 0 . 011. The fraction F R is calculated from the unitarity constraint to be F R = − 0 . 008 ± 0 . 007. These results are in agreement with the standard model predictions at next-to-next-to-leading order in perturbative quantum chromodynamics and represent an improvement in precision of 25 (29)% for F 0 ( F L ) with respect to the most precise single measurement. A limit on anomalous right-handed vector ( V R ), and left- and right-handed tensor ( g L , g R ) tWb couplings is set while fixing all others to their standard model values. The allowed regions are [ − 0 . 11 , 0 . 16] for V R , [ − 0 . 08 , 0 . 05] for g L , and [ − 0 . 04 , 0 . 02] for g R , at 95% confidence level. Limits on the corresponding Wilson coefficients are also derived.
Publisher: Elsevier BV
Date: 04-2018
Publisher: Trans Tech Publications, Ltd.
Date: 11-2005
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.297-300.2567
Abstract: Using a newly-developed Material Failure Process Analysis code (MFPA3D), the micro-fracturing process and the avalanche behavior characterization of brittle disordered materials such as rock or concrete is numerically studied under uniaxial compression and tension. It is found that, due to the heterogeneity of the disordered material, there is an avalanche behavior in the microcrack coalescence process. Meanwhile, a hierarchy of avalanche events also numerically observed though a study of numerically obtained acoustic emissions or seismic events. Numerical simulations indicate that macro-crack nucleation starts well before the peak stress is reached and the crack propagation and coalescence can be traced, which can be taken as a precursory to predict the macro-fracture of the brittle disordered materials. In addition, the numerically obtained results also reveal the presence of residual strength in the post-peak region and the resemblance in the stress-strain curves between uniaxial compression and tension.
Publisher: American Physical Society (APS)
Date: 30-08-2023
Publisher: Elsevier BV
Date: 08-2015
Publisher: Trans Tech Publications, Ltd.
Date: 11-2006
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.324-325.201
Abstract: Many stiff clays forming part of natural slopes and earth dams exist in the fissured state. When these cracks are subjected to gravity induced normal and shear stresses they may propagate. The present discussion presents a numerical method to study the propagation direction of cracks under stress fields similar to those found in the field. Not only did the results on one crack propagation direction obtained from the numerical method and the analytical results agree well, but numerical results have been used to investigate the mechanisms of the whole process of two horizontal cracks initiation and propagation and coalescence in stiff soils.
Publisher: Elsevier BV
Date: 08-2020
Publisher: Springer Science and Business Media LLC
Date: 05-2014
Publisher: Elsevier BV
Date: 08-2017
Publisher: Trans Tech Publications, Ltd.
Date: 04-2004
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.261-263.1529
Abstract: In this paper, theoretical constitutive model, numerical tool, viz., RFPA code and servo-type testing machine, viz., RMT-150B rock testing systems were briefly described, respectively. Then, based on theoretical analysis, numerical simulation and experimental tests for rock specimens in uniaxial compression, the relations and differences between theoretical, numerical and experimental results, especially the complete stress-strain curves, were contrastively analyzed and investigated. The reason for these relations and differences among results was also proposed in this paper.
Publisher: Copernicus GmbH
Date: 27-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-992
Abstract: & & The tensile strength of volcanic rock exerts control over several key volcanic processes, including fragmentation, magma chamber rupture, and dyke propagation. However, and despite this importance, values of tensile strength for volcanic rocks are relatively rare. It is also unclear how their tensile strength is modified by rock physical properties such as porosity, pore size, and pore shape and ongoing processes such as hydrothermal alteration. We present here the results of systematic laboratory and numerical experiments designed to better understand the influence of porosity, microstructural parameters (pore size, shape, and orientation), and hydrothermal alteration on the tensile strength of volcanic rocks. Our data show that tensile strength is reduced by up to an order of magnitude as porosity is increased from 0.01 to above 0.3, highlighting that porosity exerts a first-order control on the tensile strength of volcanic rocks. Our data also show that pore diameter, pore aspect ratio, and pore orientation can also influence tensile strength. Finally, our data show that hydrothermal alteration can decrease tensile strength if associated with mineral dissolution and weak secondary minerals, or increase tensile strength if associated with pore- and crack-filling mineral precipitation. We present a series of theoretical and semi-empirical constitutive models that can be used to estimate the tensile strength of volcanic rocks as a function of porosity or alteration intensity. To outline the implications of our data, we show how tensile strength estimations can influence predictions of magma overpressures and assessments of the volume and radius of a magma chamber, and we explore the influence of alteration using discrete element method modelling in which we model the amount and distribution of damage within variably-altered host-rock surrounding a pressurised dyke. It is our hope that the experiments, models, and understanding provided by our study prove useful for modellers that require the tensile strength of volcanic rocks for their models.& &
Publisher: American Physical Society (APS)
Date: 12-07-2021
Publisher: American Physical Society (APS)
Date: 23-12-2020
Publisher: Springer Science and Business Media LLC
Date: 11-2020
Abstract: A search for new physics with non-resonant signals in dielectron and dimuon final states in the mass range above 2 TeV is presented. This is the first search for non-resonant signals in dilepton final states at the LHC to use a background estimate from the data. The data, corresponding to an integrated luminosity of 139 fb − 1 , were recorded by the ATLAS experiment in proton-proton collisions at a center-of-mass energy of $$ \\sqrt{s} $$ s = 13 TeV during Run 2 of the Large Hadron Collider. The benchmark signal signature is a two-quark and two-lepton contact interaction, which would enhance the dilepton event rate at the TeV mass scale. To model the contribution from background processes a functional form is fit to the dilepton invariant-mass spectra in data in a mass region below the region of interest. It is then extrapolated to a high-mass signal region to obtain the expected background there. No significant deviation from the expected background is observed in the data. Upper limits at 95% CL on the number of events and the visible cross-section times branching fraction for processes involving new physics are provided. Observed (expected) 95% CL lower limits on the contact interaction energy scale reach 35.8 (37.6) TeV.
Publisher: Springer Science and Business Media LLC
Date: 02-2021
DOI: 10.1140/EPJC/S10052-020-08677-2
Abstract: Measurements of the Standard Model Higgs boson decaying into a $$b\\bar{b}$$ b b ¯ pair and produced in association with a W or Z boson decaying into leptons, using proton–proton collision data collected between 2015 and 2018 by the ATLAS detector, are presented. The measurements use collisions produced by the Large Hadron Collider at a centre-of-mass energy of $$\\sqrt{s} = 13\\,\\text {Te}\\text {V}$$ s = 13 Te , corresponding to an integrated luminosity of $$139\\,\\mathrm {fb}^{-1}$$ 139 fb - 1 . The production of a Higgs boson in association with a W or Z boson is established with observed (expected) significances of 4.0 (4.1) and 5.3 (5.1) standard deviations, respectively. Cross-sections of associated production of a Higgs boson decaying into bottom quark pairs with an electroweak gauge boson, W or Z , decaying into leptons are measured as a function of the gauge boson transverse momentum in kinematic fiducial volumes. The cross-section measurements are all consistent with the Standard Model expectations, and the total uncertainties vary from 30% in the high gauge boson transverse momentum regions to 85% in the low regions. Limits are subsequently set on the parameters of an effective Lagrangian sensitive to modifications of the WH and ZH processes as well as the Higgs boson decay into $$b\\bar{b}$$ b b ¯ .
Publisher: Springer Science and Business Media LLC
Date: 03-05-2018
Publisher: Springer Science and Business Media LLC
Date: 07-2020
Abstract: Single top-quark production in association with a Z boson, where the Z boson decays to a pair of charged leptons, is measured in the trilepton channel. The proton-proton collision data collected by the ATLAS experiment from 2015 to 2018 at a centre-of-mass energy of 13 TeV are used, corresponding to an integrated luminosity of 139 fb − 1 . Events containing three isolated charged leptons (electrons or muons) and two or three jets, one of which is identified as containing a b -hadron, are selected. The main backgrounds are from $$ t\\overline{t}Z $$ t t ¯ Z and diboson production. Neural networks are used to improve the background rejection and extract the signal. The measured cross-section for t ℓ + ℓ − q production, including non-resonant dilepton pairs with $$ {m}_{{\\mathrm{\\ell}}^{+}{\\mathrm{\\ell}}^{-}} $$ m ℓ + ℓ − 30 GeV, is 97 ± 13 (stat.) ± 7 (syst.) fb, consistent with the Standard Model prediction.
Publisher: Trans Tech Publications, Ltd.
Date: 09-2007
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.353-358.1045
Abstract: In this paper, some numerical tests on the fracture process zone (FPZ) in concrete tension specimen were carried out with Material Failure Process Analysis code (MFPA2D) to investigate the behavior of the FPZ and the effect of the meso-scale heterogeneity of concrete on fracture process. The numerical results provide a clear indicator of the FPZ of concrete. The numerical results show that the FPZ accompanied by AE events gradually develops ahead of the notch tip with the increase of the loading in the concrete tension specimen. Moreover, many of the AE events bring about very small energy at the beginning of loading stage. Zones of higher energy events demonstrate a localization zone around the notch tip. The zones of AE events progresses forward gradually, and much densely distributed AE events can be observed in the FPZ. Moreover, the numerical simulations about AE events agreed well with those of the microcracks obtained by laboratory findings.
Publisher: Springer Science and Business Media LLC
Date: 03-2018
Publisher: Elsevier BV
Date: 10-2020
Publisher: Springer Science and Business Media LLC
Date: 07-2021
DOI: 10.1038/S41567-021-01236-W
Abstract: The standard model of particle physics encapsulates our best current understanding of physics at the smallest scales. A fundamental axiom of this theory is the universality of the couplings of the different generations of leptons to the electroweak gauge bosons. The measurement of the ratio of the decay rate of W bosons to τ leptons and muons, R ( τ / μ ), constitutes an important test of this axiom. Using 139 fb −1 of proton–proton collisions recorded with the ATLAS detector at a centre-of-mass energy of 13 TeV, we report a measurement of this quantity from di-leptonic $$t\\overline{t}$$ t t ¯ events where the top quarks decay into a W boson and a bottom quark. We can distinguish muons originating from W bosons and those originating from an intermediate τ lepton through the muon transverse impact parameter and differences in the muon transverse momentum spectra. The measured value of R ( τ / μ ) is 0.992 ± 0.013 [± 0.007(stat) ± 0.011(syst)] and is in agreement with the hypothesis of universal lepton couplings as postulated in the standard model. This is the only such measurement from the Large Hadron Collider, so far, and obtains twice the precision of previous measurements.
Publisher: American Society of Civil Engineers (ASCE)
Date: 08-2012
Publisher: Springer Science and Business Media LLC
Date: 07-2021
Abstract: A search for long-lived particles, which have come to rest within the ATLAS detector, is presented. The subsequent decays of these particles can produce high-momentum jets, resulting in large out-of-time energy deposits in the ATLAS calorimeters. These de- cays are detected using data collected during periods in the LHC bunch structure when collisions are absent. The analysed dataset is composed of events from proton-proton collisions produced by the Large Hadron Collider at a centre-of-mass energy of $$ \\sqrt{s} $$ s = 13 TeV and recorded by the ATLAS experiment during 2017 and 2018. The dataset used for this search corresponds to a total live time of 579 hours. The results of this search are used to derive lower limits on the mass of gluino R -hadrons, assuming a branching fraction $$ \\mathcal{B}\\left(\\overset{\\sim }{g}\\to q\\overline{q}{\\chi}_1^0\\right) $$ B g ~ → q q ¯ χ 1 0 = 100%, with masses of up to 1 . 4 TeV excluded for gluino lifetimes of 10 − 5 to 10 3 s.
Publisher: Springer Science and Business Media LLC
Date: 04-02-2016
Publisher: Elsevier BV
Date: 2015
Publisher: Springer Science and Business Media LLC
Date: 07-2021
Abstract: A search for supersymmetry in events with four or more charged leptons (electrons, muons and τ -leptons) is presented. The analysis uses a data s le corresponding to 139 fb − 1 of proton-proton collisions delivered by the Large Hadron Collider at $$ \\sqrt{s} $$ s = 13 TeV and recorded by the ATLAS detector. Four-lepton signal regions with up to two hadronically decaying τ -leptons are designed to target several supersymmetric models, while a general five-lepton signal region targets any new physics phenomena leading to a final state with five charged leptons. Data yields are consistent with Standard Model expectations and results are used to set upper limits on contributions from processes beyond the Standard Model. Exclusion limits are set at the 95% confidence level in simplified models of general gauge-mediated supersymmetry, excluding higgsino masses up to 540 GeV. In R -parity-violating simplified models with decays of the lightest supersymmetric particle to charged leptons, lower limits of 1 . 6 TeV, 1 . 2 TeV, and 2 . 5 TeV are placed on wino, slepton and gluino masses, respectively.
Publisher: Trans Tech Publications, Ltd.
Date: 03-2007
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.334-335.237
Abstract: In this paper, a coupled thermal-mechanical-damage model, Material Failure Process Analysis for Thermo code (abbreviated as MFPA-thermo), was applied to investigate the formation, extension and coalescence of cracks in FRCs, caused by the thermal mismatch of the matrix and the particles under uniform temperature variations. The effects of the thermal mismatch between the matrix and fibers on the stress distribution and crack development were also numerically studied. The influences of the material heterogeneity, the failure patterns of FRCs at varied temperatures are simulated and compared with the experimental results in the present paper. The results show that the mechanisms of thermal damage and fracture of the composite remarkedably depend on the difference between the coefficients of thermal expansion of the fibers and the matrix on a meso-scale. Meanwhile, the simulations indicate that the thermal cracking of the FRCs at uniform varied temperatures is an evolution process from diffused damage, nucleation, and finally linkage of cracks.
Publisher: Elsevier BV
Date: 05-2004
Publisher: Springer Science and Business Media LLC
Date: 11-2017
Publisher: Trans Tech Publications, Ltd.
Date: 05-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMM.166-169.2995
Abstract: The principle of the structure of displacement function, the establishment of governing equations, level set method were briefly outlined in this paper. Numerical simulations on three dimensional single edge notched specimens with different crack length in tension were performed using Abaqus software based on extended finite element method (XFEM), the stress intensity factor at static crack front was analyzed and the simulated results were in good agreement with analytical solutions. Numerical simulations in the present paper indicated that the extended finite element method is very suitable to deal with nonlinear fracture problems.
Publisher: American Journal of Science (AJS)
Date: 2008
DOI: 10.2475/01.2008.02
Publisher: Springer Science and Business Media LLC
Date: 11-2020
DOI: 10.1140/EPJC/S10052-020-08469-8
Abstract: This paper presents a search for direct top squark pair production in events with missing transverse momentum plus either a pair of jets consistent with Standard Model Higgs boson decay into b -quarks or a same-flavour opposite-sign dilepton pair with an invariant mass consistent with a Z boson. The analysis is performed using the proton–proton collision data at $$\\sqrt{s}=13$$ s = 13 TeV collected with the ATLAS detector during the LHC Run-2, corresponding to an integrated luminosity of 139 fb $$^{-1}$$ - 1 . No excess is observed in the data above the Standard Model predictions. The results are interpreted in simplified models featuring direct production of pairs of either the lighter top squark ( $$\\tilde{t}_1$$ t ~ 1 ) or the heavier top squark ( $$\\tilde{t}_2$$ t ~ 2 ), excluding at 95% confidence level $$\\tilde{t}_1$$ t ~ 1 and $$\\tilde{t}_2$$ t ~ 2 masses up to about 1220 and 875 GeV, respectively.
Publisher: Springer Science and Business Media LLC
Date: 09-2015
Publisher: IOP Publishing
Date: 10-11-2020
Publisher: Trans Tech Publications, Ltd.
Date: 09-2007
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.353-358.921
Abstract: The Brazilian splitting tests have been commonly and widely used as a standardized test method on disc or cylinder specimens to measure the indirect tensile strength of rocks in mining engineering and other rock engineering. In this paper, a novel numerical code, 3D Rock Failure Process Analysis code, was applied to implement the splitting tensile failure tests on rock discs. The influences of the heterogeneity on stress distribution in rock are also discussed and the splitting failure patterns of specimens subjected to Brazilian tests are simulated. The simulated splitting results of rock discs were found quite realistic, which indicate that the rock failure analysis method is applicable and practical for the study of rock disc splitting failure.
No related grants have been discovered for Tao Xu.