A predictive safety filter for learning-based racing control

The growing need for high-performance controllers in safety-critical applications like autonomous driving has been motivating the development of formal safety verification techniques. In this paper, we design and implement a predictive safety filter that is able to maintain vehicle safety with respect to track boundaries when paired alongside any potentially unsafe control signal, such as those found in learning-based methods. A model predictive control (MPC) framework is used to create a minimally invasive algorithm that certifies whether a desired control input is safe and can be applied to the vehicle, or that provides an alternate input to keep the vehicle in bounds. To this end, we provide a principled procedure to compute a safe and invariant set for nonlinear dynamic bicycle models using efficient convex approximation techniques. To fully support an aggressive racing performance without conservative safety interventions, the safe set is extended in real-time through predictive control backup trajectories. Applications for assisted manual driving and deep imitation learning on a miniature remote-controlled vehicle demonstrate the safety filter's ability to ensure vehicle safety during aggressive maneuvers

Überinfusion von Verbrennungsopfern: häufig und schädlich

Zusammenfassung: Hintergrund: Schwerbrandverletzte (mehr als 20% verbrannter Körperoberfläche bei Erwachsenen) weisen in der ersten Phase (8-48h) einen durch das massive Kapillarleck bedingten Verbrennungsschock auf, der einer Infusionstherapie bedarf, um die Hämodynamik wieder herzustellen. Bis in die 80erJahre stellte eine unzureichende Flüssigkeitstherapie (Unterinfusion) die Haupttodesursache von Verbrennungspatienten dar. Seither ist die übermäßige Flüssigkeitstherapie (Überinfusion) zu einer beachtenswerten Quelle von Komplikationen geworden: abdominales Kompartmentsyndrom, Entlastungsschnitte (Escharotomie), Verschlechterung des Gasaustauschs, Verlängerung der künstlichen Beatmung und des Spitalaufenthalts. Die Überinfusion hat Ende der 90erJahre begonnen, wo innerhalb der ersten 24h Flüssigkeitsmengen zugeführt wurden, die weit über den 4ml/kg/%BSA ("burn surface area") der Parkland-Formel lagen. Ziel: Dieser Beitrag analysiert die Faktoren, welche zu einer Überinfusion führen können und zeigt Möglichkeiten, dem durch eine strikte Kontrolle der präklinischen Infusionstherapie sowie durch eine permissive Hypovolämie vorzubeuge

Weighted norm inequalities, off-diagonal estimates and elliptic operators. Part IV: Riesz transforms on manifolds and weights

This is the fourth article of our series. Here, we study weighted norm inequalities for the Riesz transform of the Laplace-Beltrami operator on Riemannian manifolds and of subelliptic sum of squares on Lie groups, under the doubling volume property and Gaussian upper bounds.Comment: 12 pages. Fourth of 4 papers. Important revision: improvement of main result by eliminating use of Poincar\'e inequalities replaced by the weaker Gaussian keat kernel bound

Lp-cohomology of negatively curved manifolds

We compute the $L^p$-cohomology spaces of some negatively curved manifolds. We deal with two cases: manifolds with finite volume and sufficiently pinched negative curvature, and conformally compact manifolds

Propagation of gamma rays and production of free electrons in air

A new concept of remote detection of concealed radioactive materials has been recently proposed \cite{Gr.Nusin.2010}-\cite{NusinSprangle}. It is based on the breakdown in air at the focal point of a high-power beam of electromagnetic waves produced by a THz gyrotron. To initiate the avalanche breakdown, seed free electrons should be present in this focal region during the electromagnetic pulse. This paper is devoted to the analysis of production of free electrons by gamma rays leaking from radioactive materials. Within a hundred meters from the radiation source, the fluctuating free electrons appear with the rate that may exceed significantly the natural background ionization rate. During the gyrotron pulse of about 10 microsecond length, such electrons may seed the electric breakdown and create sufficiently dense plasma at the focal region to be detected as an unambiguous effect of the concealed radioactive material.Comment: 27 pages, 10 figure

Dynamics of light propagation in spatiotemporal dielectric structures

Propagation, transmission and reflection properties of linearly polarized plane waves and arbitrarily short electromagnetic pulses in one-dimensional dispersionless dielectric media possessing an arbitrary space-time dependence of the refractive index are studied by using a two-component, highly symmetric version of Maxwell's equations. The use of any slow varying amplitude approximation is avoided. Transfer matrices of sharp nonstationary interfaces are calculated explicitly, together with the amplitudes of all secondary waves produced in the scattering. Time-varying multilayer structures and spatiotemporal lenses in various configurations are investigated analytically and numerically in a unified approach. Several new effects are reported, such as pulse compression, broadening and spectral manipulation of pulses by a spatiotemporal lens, and the closure of the forbidden frequency gaps with the subsequent opening of wavenumber bandgaps in a generalized Bragg reflector

Culture change in elite sport performance teams: Examining and advancing effectiveness in the new era

Reflecting the importance of optimizing culture for elite teams, Fletcher and Arnold (2011) recently suggested the need for expertise in culture change. Acknowledging the dearth of literature on the specific process, however, the potential effectiveness of practitioners in this area is unknown. The present paper examines the activity's precise demands and the validity of understanding in sport psychology and organizational research to support its delivery. Recognizing that sport psychologists are being increasingly utilized by elite team management, initial evidence-based guidelines are presented. Finally, to stimulate the development of ecologically valid, practically meaningful knowledge, the paper identifies a number of future research directions