Accelerated Steady-State Torque Computation for Induction Machines using Parallel-In-Time Algorithms

This paper focuses on efficient steady-state computations of induction machines. In particular, the periodic Parareal algorithm with initial-value coarse problem (PP-IC) is considered for acceleration of classical time-stepping simulations via non-intrusive parallelization in time domain, i.e., existing implementations can be reused. Superiority of this parallel-in-time method is in its direct applicability to time-periodic problems, compared to, e.g, the standard Parareal method, which only solves an initial-value problem, starting from a prescribed initial value. PP-IC is exploited here to obtain the steady state of several operating points of an induction motor, developed by Robert Bosch GmbH. Numerical experiments show that acceleration up to several dozens of times can be obtained, depending on availability of parallel processing units. Comparison of PP-IC with existing time-periodic explicit error correction method highlights better robustness and efficiency of the considered time-parallel approach

Kantenelementbasierte BEM mit DeRham-Kollokation für Elektromagnetismus

In der vorliegenden Arbeit wurden Randintegralgleichungen für elektromagnetische Probleme betrachtet und in der Sprache der Differentialformen umformuliert. Dabei können die Integralkerne als Doppelformen aufgefasst werden. Kontinuierliche Differentialformen besitzen diskrete Entsprechungen, nämlich diskrete Differentialformen, so dass die entstandene Formulierung eine natürliche Diskretisierung ermöglicht. Eine neue Vorgehensweise mit Hilfe der DeRham-Abbildungen, die hier präsentiert wird, bietet eine Alternative zur bekannten Galerkin-Diskretisierung und verallgemeinert die klassische Punktkollokationsmethode. Die hier beschriebene Randelementmethode wurde zusätzlich in einer Kopplung mit der Finite-Elemente-Methode realisiert. Einige numerische Ergebnisse der Randelementmethode und der kantenelementbasierten BEM-FEM-Kopplung sind in der Arbeit präsentiert.In the present work some integral equations of electromagnetics are reformulated in terms of differential forms. The integral kernels can be treated as double forms. The results correspond closely to the usual treatment, but are clearer and more intuitive. Since differential forms possess discrete counterparts, the discrete differential forms, such schemes lend themselves naturally to discretization. The discretization scheme generalizes the point collocation technique by using DeRham maps. The boundary element method has been considered additionally in the framework of an edge based BE-FE-coupling. Some numerical results obtained by the boundary element method and the BE-FE-coupling are presented

The 2018 Lake Louise Acute Mountain Sickness Score.

Roach, Robert C., Peter H. Hackett, Oswald Oelz, Peter Bärtsch, Andrew M. Luks, Martin J. MacInnis, J. Kenneth Baillie, and The Lake Louise AMS Score Consensus Committee. The 2018 Lake Louise Acute Mountain Sickness Score. High Alt Med Biol 19:1-4, 2018.- The Lake Louise Acute Mountain Sickness (AMS) scoring system has been a useful research tool since first published in 1991. Recent studies have shown that disturbed sleep at altitude, one of the five symptoms scored for AMS, is more likely due to altitude hypoxia per se, and is not closely related to AMS. To address this issue, and also to evaluate the Lake Louise AMS score in light of decades of experience, experts in high altitude research undertook to revise the score. We here present an international consensus statement resulting from online discussions and meetings at the International Society of Mountain Medicine World Congress in Bolzano, Italy, in May 2014 and at the International Hypoxia Symposium in Lake Louise, Canada, in February 2015. The consensus group has revised the score to eliminate disturbed sleep as a questionnaire item, and has updated instructions for use of the score

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta