Preconditioning for Allen-Cahn variational inequalities with non-local constraints

The solution of Allen-Cahn variational inequalities with mass constraints is of interest in many applications. This problem can be solved both in its scalar and vector-valued form as a PDE-constrained optimization problem by means of a primal-dual active set method. At the heart of this method lies the solution of linear systems in saddle point form. In this paper we propose the use of Krylov-subspace solvers and suitable preconditioners for the saddle point systems. Numerical results illustrate the competitiveness of this approach

Allen-Cahn and Cahn-Hilliard variational inequalities solved with Optimization Techniques

Parabolic variational inequalities of Allen-Cahn and Cahn- Hilliard type are solved using methods involving constrained optimization. Time discrete variants are formulated with the help of Lagrange multipliers for local and non-local equality and inequality constraints. Fully discrete problems resulting from finite element discretizations in space are solved with the help of a primal-dual active set approach. We show several numerical computations also involving systems of parabolic variational inequalities

Mapping the depleted area of silicon diodes using a micro-focused X-ray beam

For the Phase-II Upgrade of the ATLAS detector at CERN, the current ATLAS Inner Detector will be replaced with the ATLAS Inner Tracker. The ATLAS Inner Tracker will be an all-silicon detector, consisting of a pixel tracker and a strip tracker. Sensors for the ITk strip tracker are required to have a low leakage current up to bias voltages of -700 V to maintain a low noise and power dissipation. In order to minimise sensor leakage currents, particularly in the high-radiation environment inside the ATLAS detector, sensors are foreseen to be operated at low temperatures and to be manufactured from wafers with a high bulk resistivity of several k{\Omega} cm. Simulations showed the electric field inside sensors with high bulk resistivity to extend towards the sensor edge, which could lead to increased surface currents for narrow dicing edges. In order to map the electric field inside biased silicon sensors with high bulk resistivity, three diodes from ATLAS silicon strip sensor prototype wafers were studied with a monochromatic, micro-focused X-ray beam at the Diamond Light Source. For all devices under investigation, the electric field inside the diode was mapped and its dependence on the applied bias voltage was studied. The findings showed that the electric field in each diode under investigation extended beyond its bias ring and reached the dicing edge

Shrub expansion in tundra ecosystems: dynamics, impacts and research priorities

Part of Focus on Dynamics of Arctic and Sub-Arctic Vegetation Recent research using repeat photography, long-term ecological monitoring and dendrochronology has documented shrub expansion in arctic, high-latitude and alpine tundra ecosystems. Here, we (1) synthesize these findings, (2) present a conceptual framework that identifies mechanisms and constraints on shrub increase, (3) explore causes, feedbacks and implications of the increased shrub cover in tundra ecosystems, and (4) address potential lines of investigation for future research. Satellite observations from around the circumpolar Arctic, showing increased productivity, measured as changes in 'greenness', have coincided with a general rise in high-latitude air temperatures and have been partly attributed to increases in shrub cover. Studies indicate that warming temperatures, changes in snow cover, altered disturbance regimes as a result of permafrost thaw, tundra fires, and anthropogenic activities or changes in herbivory intensity are all contributing to observed changes in shrub abundance. A large-scale increase in shrub cover will change the structure of tundra ecosystems and alter energy fluxes, regional climate, soil–atmosphere exchange of water, carbon and nutrients, and ecological interactions between species. In order to project future rates of shrub expansion and understand the feedbacks to ecosystem and climate processes, future research should investigate the species or trait-specific responses of shrubs to climate change including: (1) the temperature sensitivity of shrub growth, (2) factors controlling the recruitment of new individuals, and (3) the relative influence of the positive and negative feedbacks involved in shrub expansion

Detection of batch activities from event logs

Organizations carry out a variety of business processes in order to serve their clients. Usually supported by information technology and systems, process execution data is logged in an event log. Process mining uses this event log to discover the process’ control-flow, its performance, information about the resources, etc. A common assumption is that the cases are executed independently of each other. However, batch work – the collective execution of cases for specific activities – is a common phenomenon in operational processes to save costs or time. Existing research has mainly focused on discovering individual batch tasks. However, beyond this narrow setting, batch processing may consist of the execution of several linked tasks. In this work, we present a novel algorithm which can also detect parallel, sequential and concurrent batching over several connected tasks, i.e., subprocesses. The proposed algorithm is evaluated on synthetic logs generated by a business process simulator, as well as on a real-world log obtained from a hospital’s digital whiteboard system. The evaluation shows that batch processing at the subprocess level can be reliably detected.Detection of batch activities from event logssubmittedVersio

Auswirkungen der Fröbelpädagogik auf das Umweltbewusstsein im Sachunterricht

Naturverbundenheit gilt als ein entscheidender Prädiktor für Umweltbewusstsein und somit für umweltfreundliches Verhalten1. Um der vorherrschenden ökologischen Krise entgegenzuwirken, ist eine erfolgreiche Rückbindung des Einzelnen an die Natur erforderlich. Auch Friedrich Fröbel sah in seinem Bildungs- und Erziehungsmodell die Einbeziehung der Natur als grundlegend an, sowohl für eine gesunde Entwicklung, als auch als entscheidend für die Ausbildung ethischen Verhaltens2. Diese Masterarbeit untersucht die Auswirkungen der Anwendung von Elementen der Pädagogik Friedrich Fröbels im Sachunterricht auf die Naturverbundenheit von Grundschulkindern. Anwendung findet hier ein quasiexperimentelles Forschungsdesign, welches in drei Phasen angelegt ist. Die geplanten Befragungen mittels standardisierter Fragebögen gehören zur ersten und dritten Phase und bilden den Pre- und Posttest. In diesen Phasen soll durch die Nutzung des Connection to Nature Index (CNI) nach Cheng/Monroe 2012 die Verbundenheit zur Natur erforscht werden3. Die Intervention in der zweiten Phase wurde innerhalb von drei Schulstunden zur Thematik Überwinterungsstrategien von Pflanzen und Bäumen im Sachunterricht durchgeführt. Kinder aus der Parallelklasse, die nicht an der Intervention teilnahmen, erhielten Klassenunterricht zu diesem Thema und dienten somit als Kontrollgruppe. Die Ergebnisse deuten darauf hin, dass die Anwendung fröbelpädagogischer Elemente im Sachunterricht eine stärkere Naturverbundenheit der Lernenden hervorruft, als signifikant erwies sich diese Aussage jedoch nicht (p = .129). ------------- 1 Vgl. Cervinka/Schmuck 2010, zitiert nach Cervinka, Renate/Schwab, Markus (2020): Naturverbundenheit – Ergebnisse der umweltpsychologischen Forschung für Agrar- und Umweltpädagogik und Green Care. In: Zeitschrift für Agrar- und Umweltpädagogische Forschung, Band 2, S. 10. 2 Vgl. Frey, Andreas/Gehrlein, Birgit/Wosnitza, Marold (2001): Fröbels ganzheitliche Pädagogik. Landau: Verlag Empirischer Pädagogik, S. 76f. 3 Vgl. Cheng, Judith Chen-Hsuan/Monroe, Martha C. (2012): Connection to nature: Children’s affective attitude toward nature. In: Environment and Behavior, 44, 1, S. 31

Measurements of neutrino oscillation in appearance and disappearance channels by the T2K experiment with 6.6 x 10(20) protons on target

111 pages, 45 figures, submitted to Physical Review D. Minor revisions to text following referee comments111 pages, 45 figures, submitted to Physical Review D. Minor revisions to text following referee comments111 pages, 45 figures, submitted to Physical Review D. Minor revisions to text following referee commentsWe thank the J-PARC staff for superb accelerator performance and the CERN NA61/SHINE Collaboration for providing valuable particle production data. We acknowledge the support of MEXT, Japan; NSERC, NRC, and CFI, Canada; CEA and CNRS/IN2P3, France; DFG, Germany; INFN, Italy; National Science Centre (NCN), Poland; RSF, RFBR and MES, Russia; MINECO and ERDF funds, Spain; SNSF and SER, Switzerland; STFC, UK; and the U. S. Deparment of Energy, USA. We also thank CERN for the UA1/NOMAD magnet, DESY for the HERA-B magnet mover system, NII for SINET4, the WestGrid and SciNet consortia in Compute Canada, GridPP, UK, and the Emerald High Performance Computing facility in the Centre for Innovation, UK. In addition, participation of individual researchers and institutions has been further supported by funds from ERC (FP7), EU; JSPS, Japan; Royal Society, UK; and DOE Early Career program, USA

Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb^-1. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results