Cryogenic fluid flow instabilities in heat exchangers

Analytical and experimental investigation determines the nature of oscillations and instabilities that occur in the flow of two-phase cryogenic fluids at both subcritical and supercritical pressures in heat exchangers. Test results with varying system parameters suggest certain design approaches with regard to heat exchanger geometry

The solar dynamic radiator with a historical perspective

A historical perspective on pumped-fluid loop space radiators provides a basis for the design of the Space Station Solar Dynamic (SD) power module radiator. SD power modules, capable of generating 25 kW (electrical) each, are planned for growth in Station power requirements. The Brayton cycle SD module configuration incorporates a pumped-fluid loop radiator that must reject up to 99 kW (thermal). The thermal/hydraulic design conditions in combination with required radiator orientation and packaging envelope form a unique set of constraints as compared to previous pumped-fluid loop radiator systems. Nevertheless, past program successes have demonstrated a technology base that can be applied to the SD radiator development program to ensure a low risk, low cost system

Thermal-neutron cross section for 10(n,t)2_ via 3-4He mass spectrometry

The thermal cross section for the reaction 10He is determined to be 4.47±0.15 mb by neutron irradiation of H3BO3 followed by measurement of 3He (from decay of 3H) and 4He in a static mass spectrometer. Some samples contained boron of normal isotopic composition and some were enriched in 10B, and irradiations were carried out in a highly thermalized neutron flux and in the core of a light-water-moderated reactorPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86120/1/PhysRevC.39.1633.pd

Imaging analysis of LDEF craters

Two small craters in Al from the Long Duration Exposure Facility (LDEF) experiment tray A11E00F (no. 74, 119 micron diameter and no. 31, 158 micron diameter) were analyzed using Auger electron spectroscopy (AES), time-of-flight secondary ion mass spectroscopy (TOF-SIMS), low voltage scanning electron microscopy (LVSEM), and SEM energy dispersive spectroscopy (EDS). High resolution images and sensitive elemental and molecular analysis were obtained with this combined approach. The result of these analyses are presented

Path integrals and symmetry breaking for optimal control theory

This paper considers linear-quadratic control of a non-linear dynamical system subject to arbitrary cost. I show that for this class of stochastic control problems the non-linear Hamilton-Jacobi-Bellman equation can be transformed into a linear equation. The transformation is similar to the transformation used to relate the classical Hamilton-Jacobi equation to the Schr\"odinger equation. As a result of the linearity, the usual backward computation can be replaced by a forward diffusion process, that can be computed by stochastic integration or by the evaluation of a path integral. It is shown, how in the deterministic limit the PMP formalism is recovered. The significance of the path integral approach is that it forms the basis for a number of efficient computational methods, such as MC sampling, the Laplace approximation and the variational approximation. We show the effectiveness of the first two methods in number of examples. Examples are given that show the qualitative difference between stochastic and deterministic control and the occurrence of symmetry breaking as a function of the noise.Comment: 21 pages, 6 figures, submitted to JSTA

Are 3D virtual environments better than 2D interfaces in serious games performance? An explorative study for the assessment of executive functions

This is an Accepted Manuscript of an article published by Taylor & Francis in Applied Neuropsychology: Adult on 05/09/2019, available online: http://www.tandfonline.com/10.1080/23279095.2019.1607735[EN] Executive functions refer to higher-order cognitive processes that supervise and guide goaldirected and adaptive behaviors in response to everyday situations. The traditional measures used to assess executive functions include paper-and-pencil tests and/or computerized tests that have been found to have a moderate level of ecological validity in predicting real-world performance. Serious games (SG) represent a novel methodological approach, allowing investigating subjects¿ performance in real-simulated situations. Serious games are computer games whose primary purposes include investigating human behaviors and changes. Furthermore, SG can also vary according to the technology used and the interaction. Indeed, a SG can be rendered via a nonimmersive screen-based (2D) or via an immersive virtual reality game (3D). Starting from these premises, we compared a narrativecontextualized SG in 2D and 3D, correlating them with traditional tests. Findings showed different condition correlations with the traditional tasks and the comparison between the two systems have revealed that 3D is able to generate lower reaction times, higher correct answers, and lower perseverative responses in attentional abilities, inhibition control, and cognitive shifting than 2D condition. The present study yielded evidence on the use of more ecological tools to identify the functional cognitive status in real-simulated contexts along with traditional evaluation.This work was supported by the Spanish Ministry of Economy, Industry, and Competitiveness funded project Advanced Therapeutically Tools for Mental Health (DPI2016-77396-R).Chicchi-Giglioli, IA.; Juan-Ripoll, CD.; Parra Vargas, E.; Alcañiz Raya, ML. 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Outbreak of acute hepatitis C following the use of anti-hepatitis C virus--screened intravenous immunoglobulin therapy

BACKGROUND and AIMS: Hepatitis C virus (HCV) infection has been associated with intravenous (IV) immunoglobulin (Ig), and plasma donations used to prepare IV Ig are now screened to prevent transmission. Thirty-six patients from the United Kingdom received infusions from a batch of anti-HCV antibody-screened intravenous Ig (Gammagard; Baxter Healthcare Ltd., Thetford, Norfolk, England) that was associated with reports of acute hepatitis C outbreak in Europe. The aim of this study was to document the epidemiology of this outbreak. METHODS: Forty-six patients from the United Kingdom treated with Gammagard (34 exposed and 12 unexposed to the batch) returned epidemiological questionnaires. RESULTS: Eighty-two percent of the exposed patients (28 of 34) became positive for HCV RNA. Eighteen percent of the patients (6 of 34) who had infusions with this batch tested negative for HCV RNA, but 2 of the patients had abnormal liver function and subsequently seroconverted to anti-HCV antibody positive. Twenty-seven percent of the patients (9 of 34) developed jaundice, and 79% (27 of 34) had abnormal liver transferase levels. Virus isolates (n=21), including an isolate from the implicated batch, were genotype 1a and virtually identical by sequence analysis of the NS5 region, consistent with transmission from a single source. CONCLUSIONS: Hepatitis C infection can be transmitted by anti-HCV-screened IV Ig. Careful documentation of IV Ig batch numbers and regular biochemical monitoring is recommended for all IV Ig recipients

Economic Feasibility of Impermeable Lagoon Covers

Environmental Economics and Policy,