32,034 research outputs found

    A guideline for heavy ion radiation testing for Single Event Upset (SEU)

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    A guideline for heavy ion radiation testing for single event upset was prepared to assist new experimenters in preparing and directing tests. How to estimate parts vulnerability and select an irradiation facility is described. A broad brush description of JPL equipment is given, certain necessary pre-test procedures are outlined and the roles and testing guidelines for on-site test personnel are indicated. Detailed descriptions of equipment needed to interface with JPL test crew and equipment are not provided, nor does it meet the more generalized and broader requirements of a MIL-STD document. A detailed equipment description is available upon request, and a MIL-STD document is in the early stages of preparation

    Multi-agent collaborative search : an agent-based memetic multi-objective optimization algorithm applied to space trajectory design

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    This article presents an algorithm for multi-objective optimization that blends together a number of heuristics. A population of agents combines heuristics that aim at exploring the search space both globally and in a neighbourhood of each agent. These heuristics are complemented with a combination of a local and global archive. The novel agent-based algorithm is tested at first on a set of standard problems and then on three specific problems in space trajectory design. Its performance is compared against a number of state-of-the-art multi-objective optimization algorithms that use the Pareto dominance as selection criterion: non-dominated sorting genetic algorithm (NSGA-II), Pareto archived evolution strategy (PAES), multiple objective particle swarm optimization (MOPSO), and multiple trajectory search (MTS). The results demonstrate that the agent-based search can identify parts of the Pareto set that the other algorithms were not able to capture. Furthermore, convergence is statistically better although the variance of the results is in some cases higher

    Giant Fluctuations of Coulomb Drag in a Bilayer System

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    We have observed reproducible fluctuations of the Coulomb drag, both as a function of magnetic field and electron concentration, which are a manifestation of quantum interference of electrons in the layers. At low temperatures the fluctuations exceed the average drag, giving rise to random changes of the sign of the drag. The fluctuations are found to be much larger than previously expected, and we propose a model which explains their enhancement by considering fluctuations of local electron properties.Comment: 10 pages, 4 figure

    Artifacts at 4.5 and 8.0 um in Short Wavelength Spectra from the Infrared Space Observatory

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    Spectra from the Short Wavelength Spectrometer (SWS) on ISO exhibit artifacts at 4.5 and 8 um. These artifacts appear in spectra from a recent data release, OLP 10.0, as spurious broad emission features in the spectra of stars earlier than ~F0, such as alpha CMa. Comparison of absolutely calibrated spectra of standard stars to corresponding spectra from the SWS reveals that these artifacts result from an underestimation of the strength of the CO and SiO molecular bands in the spectra of sources used as calibrators by the SWS. Although OLP 10.0 was intended to be the final data release, these findings have led to an additional release addressing this issue, OLP 10.1, which corrects the artifacts.Comment: 14 pages, AASTex, including 5 figures. Accepted by ApJ Letter

    A BIOMECHANICAL AND PHYSIOLOGICAL ANALYSIS OF EFFICIENCY AT DIFFERENT RUNNING PACES

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    The purpose of this study was to investigate the differences between several biomechanical and physiological variables associated with two different paces in treadmill running. The treadmill speed was adjusted to simulate an easy warm-up pace and a race pace for a 5000 m run. Another purpose was to study the contribution of both biomechanical and physiological variables toward total efficiency. The biomechanical variables included: (a) stride frequency, (b) stride length, (c) time of stride, and (d) percent of support. The physiological variables included: (a) heart rate, (b) R value, (c) V02, (d) percent of V02max, and (e) blood lactate. Nine intercollegiate distance runners from the north Texas area were filmed twice (5 min and 15 min) .from a sagittal view with a 16 mm high speed camera operating at 100 fps during two running paces. Joint segment markers were attached to the runners and one complete stride was digitized. The X/Y coordinates were used to determine the work per stride. Since physiological data were being collected simultaneously during the treadmill protocol, these were matched to the 5 min and 15 min film data intervals to determine total efficiency. A one-way repeated measures ANOVA was utilized with two paces and two times to investigate the biomechanical, physiological, and efficiency variables. Maximum experimentwise error control for Type I errors was necessary since ten dependent variables were utilized and the correlation matrix indicated that the data were nonorthogonal. A Bonferroni inequality test was also used and produced a modified alpha level of .005. No significant interactions for time by pace were found for any of the dependent variables. However, a trend does exist for several of the variables

    ARIA 2016 : Care pathways implementing emerging technologies for predictive medicine in rhinitis and asthma across the life cycle

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    European Innovation Partnership on Active and Healthy Ageing Reference Site MACVIA-France, EU Structural and Development Fund Languedoc-Roussillon, ARIA.Peer reviewedPublisher PD

    Life, Death and Preferential Attachment

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    Scientific communities are characterized by strong stratification. The highly skewed frequency distribution of citations of published scientific papers suggests a relatively small number of active, cited papers embedded in a sea of inactive and uncited papers. We propose an analytically soluble model which allows for the death of nodes. This model provides an excellent description of the citation distributions for live and dead papers in the SPIRES database. Further, this model suggests a novel and general mechanism for the generation of power law distributions in networks whenever the fraction of active nodes is small.Comment: 5 pages, 2 figure
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