Liquid vapor phase transitions : modeling, Riemann solvers and computation

The numerical approximation of liquid vapor flows within the compressible regime is a challenging task because complex physical effects at the phase interfaces govern the global flow behavior. We develop a sharp interface approach which treats the phase boundary like a shock wave discontinuity and takes capillarity effects into account. The approach relies on the solution of Riemann problems across the interface that separates the liquid and the vapor phase. The Riemann solution accounts for the relevant physics by enforcing appropriate jump conditions at the phase boundary. A wide variety of interface effects can be handled in a thermodynamically consistent way. This includes surface tension, as well as, mass and energy transfer by phase transition. Moreover, the local normal speed of the interface, which is needed to calculate the time evolution of the phase boundary, is given by the Riemann solution. The focus of this work is the development of isothermal and non-isothermal two-phase Riemann solvers for the sharp interface approach. To verify the solvers with respect to numerical and thermodynamic requirements, one-dimensional and radially symmetric problems are studied. Furthermore, the Riemann solvers and the sharp interface approach are successfully validated against shock tube experiments of real fluids (alkanes).Die numerische Approximation von Zweiphasenströmungen (flüssig/Dampf) in kompressiblen Medien ist eine Herausforderung, da komplexe physikalische Effekte an der Phasengrenze das globale Strömungsverhalten bestimmen. Wir entwickeln einen Sharp-Interface Ansatz, der Phasengrenzen als Schockwellen-Unstetigkeiten behandelt und Kapillareffekte berücksichtigt. Der Ansatz beruht auf der Lösung von Riemann-Problemen an der Grenzfläche zwischen Flüssigkeit und Dampf. Die Riemann-Lösung berücksichtigt relevante physikalische Effekte, indem Sprungbedingungen an der Phasengrenze vorgegeben werden. Dadurch kann eine Vielzahl an Grenzeffekten, wie Oberflächenspannung, Massen- und Energieaustausch durch Phasenübergänge, thermodynamisch konsistent gehandhabt werden. Darüber hinaus ist die lokale Geschwindigkeit in Normalenrichtung, die für die Berechnung der zeitlichen Entwicklung der Phasengrenze benötigt wird, durch die Riemann-Lösungen bestimmt. Der Schwerpunkt dieser Arbeit liegt auf der Entwicklung von isothermen und nicht-isothermen Zweiphasen-Riemannlösern für den Sharp-Interface Ansatz. Zur Verifizierung der Löser bezüglich numerischer und thermodynamischer Anforderungen werden eindimensionale und radial symmetrische Probleme untersucht. Darüber hinaus werden die Riemannlöser und der Sharp-Interface Ansatz erfolgreich durch den Vergleich mit Stoßrohr-Experimenten mit echten Fluiden (Alkane) validiert

Therapeutic drug monitoring in adolescents with anorexia nervosa for safe treatment with adjunct olanzapine

Objective: Medication is commonly used in anorexia nervosa (AN) despite largely missing high grade evidence. Olanzapine (OLZ) is the best-evidenced substance used off-label in this group, with conflicting outcome regarding BMI, clinical and safety parameters. Therefore, it is important to strictly assure quality of treatment with OLZ in AN by using 'Therapeutic Drug Monitoring' according to AGNP-guidelines, including serum levels and adverse drug reactions (ADRs) to support safety for adolescents with AN and attempt to generate an initial age- and disorder-specific therapeutic reference range. Method: Sixty-five adolescents with AN (aged 10-18) treated with OLZ (98% female; 97.5% AN-restricting-type) were prospectively observed, ADRs reported, and correlations between dosage and serum levels measured at trough level were calculated, a preliminary therapeutic range defined. Results: Mean dosage of OLZ was 8.15 (SD: 2.91) mg and 0.19 (SD: 0.07) mg/kg respectively, average concentration was 26.57 (SD: 13.46) ng/mL. Correlation between daily dosage/dosage per kg and serum level was 0.72 (**p < 0.001)/0.65 (**p < 0.001), respectively. ADRs with impairment were rare (6.3%). 75% improved clinically (CGI). BMI increased significantly by 1.5 kg/m2 (t = 10.6, p < 0.001). A preliminary therapeutic reference range is 11.9 and 39.9 ng/mL. Conclusions: OLZ in the hands of specialists is a well-tolerated and safe treatment adjunct for adolescents with AN

Deep Unsupervised Multi-View Detection of Video Game Stream Highlights

We consider the problem of automatic highlight-detection in video game streams. Currently, the vast majority of highlight-detection systems for games are triggered by the occurrence of hard-coded game events (e.g., score change, end-game), while most advanced tools and techniques are based on detection of highlights via visual analysis of game footage. We argue that in the context of game streaming, events that may constitute highlights are not only dependent on game footage, but also on social signals that are conveyed by the streamer during the play session (e.g., when interacting with viewers, or when commenting and reacting to the game). In this light, we present a multi-view unsupervised deep learning methodology for novelty-based highlight detection. The method jointly analyses both game footage and social signals such as the players facial expressions and speech, and shows promising results for generating highlights on streams of popular games such as Player Unknown's Battlegrounds

Behaviorally Efficient Remedies An Experiment

Under common law, the standard remedy for breach of contract is expectation damages. Under continental law, the standard is specific performance. The common law solution is ex post efficient. But is it also ex ante efficient? We use experimental methods to test whether knowing that non-fulfilment will only lead to damages deters mutually beneficial trade. The design excludes aversion against others willfully breaking their promises. We find that there is indeed less trade if specific performance is not guaranteed, provided the preference for the traded commodity is sufficiently pronounced

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A multiscale method for compressible liquid-vapor flow with surface tension*

Discontinuous Galerkin methods have become a powerful tool for approximating the solution of compressible flow problems. Their direct use for two-phase flow problems with phase transformation is not straightforward because this type of flows requires a detailed tracking of the phase front. We consider the fronts in this contribution as sharp interfaces and propose a novel multiscale approach. It combines an efficient high-order Discontinuous Galerkin solver for the computation in the bulk phases on the macro-scale with the use of a generalized Riemann solver on the micro-scale. The Riemann solver takes into account the effects of moderate surface tension via the curvature of the sharp interface as well as phase transformation. First numerical experiments in three space dimensions underline the overall performance of the method