1,867 research outputs found

    Design of hydraulic output Stirling engine

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    A hydraulic output system for the RE-1000 free piston stirling engine (FPSE) was designed. The hydraulic output system can be readily integrated with the existing hot section of RE-1000 FPSE. The system has two simply supported diaphragms which separate the engine gas from the hydraulic fluid, a dynamic balance mechanism, and a novel, null center band hydraulic pump. The diaphragms are designed to endure more than 10 billion cycles, and to withstand the differential pressure load as high as 14 MPa. The projected thermodynamic performance of the hydraulic output version of RE-1000 FPSE is 1.87 kW at 29/7 percent brake efficiency

    Production of doubly charged vector bilepton pairs at γγ\gamma \gamma colliders

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    The production of pairs of doubly charged vector bileptons is studied at future γγ\gamma \gamma colliders. The unpolarized cross--section for the γγYY++\gamma \gamma \to Y^{--}Y^{++} subprocess is analytically calculated and convoluted to predict the number of events in the complete e+eγγYY++e^+e^-\to \gamma \gamma \to Y^{--}Y^{++} process. The gauge or non--gauge character of the vector bilepton Y±±Y^{\pm \pm} is discussed. It is found that as a consequence of its spectacular signature, as it decays dominantly into two identical charged leptons, and also due to its charge contents, which significantly enhance the cross--section, the detection of this class of particles with mass in the sub--TeV region can be at the reach of these colliders. The model--independent nature of our results is stressed.Comment: 9 pages, 7 figures, submitted to physical review

    Summary of Payload Integration Plan (PIP) for Starlab-1 flight experiment, enclosure 3

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    The objectives of the Autogenic Feedback Training (AFT) are to: determine if preflight AFT is an effective treatment for space adaptation syndrome (SAS); determine if preflight improvements in motion sickness tolerance can be used to predict crewmembers' success in controlling symptoms in flight; and identify differences and similarities between the physiological data from preflight motion sickness tests and data collected during symptom episodes in space. The goal is to test the AFT on 8 trained and 8 control subjects. At present 2 trained and 2 contol subjects were tested. The testing will continue until the experimental goal of testing 16 individual is reached

    Sub-Planck phase-space structures and Heisenberg-limited measurements

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    We show how sub-Planck phase-space structures in the Wigner function can be used to achieve Heisenberg-limited sensitivity in weak force measurements. Nonclassical states of harmonic oscillators, consisting of superpositions of coherent states, are shown to be useful for the measurement of weak forces that cause translations or rotations in phase space, which is done by entangling the quantum oscillator with a two-level system. Implementations of this strategy in cavity QED and ion traps are described.Comment: 7 pages, 2 figure

    Nanoplasmonics beyond Ohm's law

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    In tiny metallic nanostructures, quantum confinement and nonlocal response change the collective plasmonic behavior with important consequences for e.g. field-enhancement and extinction cross sections. We report on our most recent developments of a real-space formulation of an equation-of-motion that goes beyond the common local-response approximation and use of Ohm's law as the central constitutive equation. The electron gas is treated within a semi-classical hydrodynamic model with the emergence of a new intrinsic length scale. We briefly review the new governing wave equations and give examples of applying the nonlocal framework to calculation of extinction cross sections and field enhancement in isolated particles, dimers, and corrugated surfaces.Comment: Invited paper for TaCoNa-Photonics 2012 (www.tacona-photonics.org), to appear in AIP Conf. Pro

    Medical Data Architecture Platform and Recommended Requirements for a Medical Data System for Exploration Missions

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    The Medical Data Architecture (MDA) project supports the Exploration Medical Capability (ExMC) risk to minimize or reduce the risk of adverse health outcomes and decrements in performance due to in-flight medical capabilities on human exploration missions. To mitigate this risk, the ExMC MDA project addresses the technical limitations identified in ExMC Gap Med 07: We do not have the capability to comprehensively process medically- relevant information to support medical operations during exploration missions. This gap identifies that the current in-flight medical data management includes a combination of data collection and distribution methods that are minimally integrated with on-board medical devices and systems. Furthermore, there are a variety of data sources and methods of data collection. For an exploration mission, the seamless management of such data will enable a more medically autonomous crew than the current paradigm of medical data management on the International Space Station. ExMC has recognized that in order to make informed decisions about a medical data architecture framework, current methods for medical data management must not only be understood, but an architecture must also be identified that provides the crew with actionable insight to medical conditions. This medical data architecture will provide the necessary functionality to address the challenges of executing a self-contained medical system that approaches crew health care delivery without assistance from ground support. Hence, the products derived from the third MDA prototype development will directly inform exploration medical system requirements for Level of Care IV in Gateway missions. In fiscal year 2019, the MDA project developed Test Bed 3, the third iteration in a series of prototypes, that featured integrations with cognition tool data, ultrasound image analytics and core Flight Software (cFS). Maintaining a layered architecture design, the framework implemented a plug-in, modular approach in the integration of these external data sources. An early version of MDA Test Bed 3 software was deployed and operated in a simulated analog environment that was part of the Next Space Technologies for Exploration Partnerships (NextSTEP) Gateway tests of multiple habitat prototypes. In addition, the MDA team participated in the Gateway Test and Verification Demonstration, where the MDA cFS applications was integrated with Gateway-in-a-Box software to send and receive medically relevant data over a simulated vehicle network. This software demonstration was given to ExMC and Gateway Program stakeholders at the NASA Johnson Space Center Integrated Power, Avionics and Software (iPAS) facility. Also, the integrated prototypes served as a vehicle to provide Level 5 requirements for the Crew Health and Performance Habitat Data System for Gateway Missions (Medical Level of Care IV). In the upcoming fiscal year, the MDA project will continue to provide systems engineering and vertical prototypes to refine requirements for medical Level of Care IV and inform requirements for Level of Care V

    Quantum to classical transition in a system with a mixed classical dynamics

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    We study how decoherence rules the quantum-classical transition of the Kicked Harmonic Oscillator (KHO). When the amplitude of the kick is changed the system presents a classical dynamics that range from regular to a strong chaotic behavior. We show that for regular and mixed classical dynamics, and in the presence of noise, the distance between the classical and the quantum phase space distributions is proportional to a single parameter χKeff2/4D3/2\chi\equiv K\hbar_{\rm eff}^2/4D^{3/2} which relates the effective Planck constant eff\hbar_{\rm eff}, the kick amplitude KK and the diffusion constant DD. This is valid when χ<1\chi < 1, a case that is always attainable in the semiclassical regime independently of the value of the strength of noise given by DD. Our results extend a recent study performed in the chaotic regime.Comment: 10 pages, 7 figure

    Decoherence and the quantum-classical limit in the presence of chaos

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    We investigate how decoherence affects the short-time separation between quantum and classical dynamics for classically chaotic systems, within the framework of a specific model. For a wide range of parameters, the distance between the corresponding phase-space distributions depends on a single parameter χ\chi that relates an effective Planck constant eff\hbar_{\rm eff}, the Lyapunov coeffficient, and the diffusion constant. This distance peaks at a time that depends logarithmically on eff\hbar_{\rm eff}, in agreement with previous estimations of the separation time for Hamiltonian systems. However, for χ1\chi\lesssim 1, the separation remains small, going down with eff2\hbar_{\rm eff}^2, so the concept of separation time loses its meaning.Comment: 5 pages, 4 figures (in 6 postscript files) two of them are color figure
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