9,417 research outputs found

    Inclusion of explicit thermal requirements in optimum structural design

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    A finite-element based procedure is described for obtaining minimum mass designs of structures subjected to combined thermal and mechanical loading and both strength and thermal constraints. The procedure is based on a mathematical programming method using the Sequence of Unconstrained Minimizations Technique (SUMT) in which design requirements are incorporated by an exterior penalty function. The procedure is limited to steady-state temperatures which are controlled by structural sizing only. The optimization procedure is demonstrated by the design of a structural wing box with both mechanical loading and external heating, subject to design constraints on stress, minimum gage, and temperature. The final design for these conditions is compared with a corresponding design in which temperature constraints are omitted

    Numerical procedure to determine geometric view factors for surfaces occluded by cylinders

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    A numerical procedure was developed to determine geometric view factors between connected infinite strips occluded by any number of infinite circular cylinders. The procedure requires a two-dimensional cross-sectional model of the configuration of interest. The two-dimensional model consists of a convex polygon enclosing any number of circles. Each side of the polygon represents one strip, and each circle represents a circular cylinder. A description and listing of a computer program based on this procedure are included in this report. The program calculates geometric view factors between individual strips and between individual strips and the collection of occluding cylinders

    Many-Body Corrections to Charged-Current Neutrino Absorption Rates in Nuclear Matter

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    Including nucleon--nucleon correlations due to both Fermi statistics and nuclear forces, we have developed a general formalism for calculating the charged--current neutrino--nucleon absorption rates in nuclear matter. We find that at one half nuclear density many--body effects alone suppress the rates by a factor of two and that the suppression factors increase to ∼\sim5 at 4×10144\times10^{14} g cm−3^{-3}. The associated increase in the neutrino--matter mean--free--paths parallels that found for neutral--current interactions and opens up interesting possibilities in the context of the delayed supernova mechanism and protoneutron star cooling.Comment: 11 pages, APS REVTeX format, 1 PostScript figure, uuencoded compressed, and tarred, submitted to Physical Review Letter

    A Framework to Manage the Complex Organisation of Collaborating: Its Application to Autonomous Systems

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    In this paper we present an analysis of the complexities of large group collaboration and its application to develop detailed requirements for collaboration schema for Autonomous Systems (AS). These requirements flow from our development of a framework for collaboration that provides a basis for designing, supporting and managing complex collaborative systems that can be applied and tested in various real world settings. We present the concepts of "collaborative flow" and "working as one" as descriptive expressions of what good collaborative teamwork can be in such scenarios. The paper considers the application of the framework within different scenarios and discuses the utility of the framework in modelling and supporting collaboration in complex organisational structures

    The discovery of optical emission from the SNR G 126.2 + 1.6

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    Interference filter photographs were used to identify an arc of nebulosity that is coincident with the radio contours of the galactic supernova remnant G 126.2 + 1.6. Spectrophotometry of the filament shows that the emission line spectrum matches the spectra of other galactic supernova remnants. In particular, the arc shows the usual strong SII, and NII emission lines seen in other remnants and unusually strong OII emission as seen in a few remnants. The spectrum can be adequately matched by a shock of velocity near 100 km/s in an interstellar cloud of density 3. If the SNR is at a distance of 4.5 kpc as indicated by the radio signal-D relation, then the observed pressure in the filament requires an initial energy near 4 x 10 to the 51st power (d/4.5 kpc) to the 3rd power ergs

    On a scalable nonparametric denoising of time series signals

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    Denoising and filtering of time series signals is a problem emerging in many areas of computational science. Here we demonstrate how the nonparametric computational methodology of the finite element method of time series analysis with H1 regularization can be extended for denoising of very long and noisy time series signals. The main computational bottleneck is the inner quadratic programming problem. Analyzing the solvability and utilizing the problem structure, we suggest an adapted version of the spectral projected gradient method (SPG-QP) to resolve the problem. This approach increases the granularity of parallelization, making the proposed methodology highly suitable for graphics processing unit (GPU) computing. We demonstrate the scalability of our open-source implementation based on PETSc for the Piz Daint supercomputer of the Swiss Supercomputing Centre (CSCS) by solving large-scale data denoising problems and comparing their computational scaling and performance to the performance of the standard denoising methods

    Phosphorus indexing for cropland: Overview and basic concepts of the Iowa phosphorus index

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    Excessive phosphorus (P) loss from soils impairs surface water resources. An assessment tool or index has been proposed to identify fields with high potential risk of P delivery. The P index integrates P source and transport factors into a decision making process that may lead to changes in current P management and soil conservation practices. The index recognizes that a single soil P threshold alone is not an appropriate evaluation factor because of the varying conditions across fields. Although most indices being developed in the United States include similar factors, source and transport characteristics are considered in various ways to best address the variable conditions across regions. The Iowa P index reflects conditions that predominate under grain-crop production systems, considers source factors in a multiplicative manner within three main transport mechanisms, and approximates loads of P likely to enter and become available to aquatic ecosystems. An erosional component considers sheet and rill erosion, P enrichment, total soil P, buffers, sediment delivery, distance to a stream, and the long term biotic availability of particulate P in lake ecosystems. A runoff component considers water runoff based on a modification of the runoff curve number (RCN), soil-test P (STP), rate, time, and method of P application. An internal drainage component considers the presence of tiles, water flow to tile lines, subsurface recharge from subsurface flow, and soil-test P. When the erosion risk is high, the index weighs particulate P loss heavily compared with dissolved P loss, and emphasizes long-term processes comparatively more than short-term processes. This P assessment tool helps identify alternative P and soil conservation management options for reducing total P delivery from fields to surface water resources

    Social networks, social capital and end-of-life care for people with dementia: a realist review

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    OBJECTIVES (1) To develop an understanding of how social capital may be conceptualised within the context of endof-life care and how it can influence outcomes for people with dementia and their families with specific reference to the context and mechanisms that explain observed outcomes. (2) To produce guidance for healthcare systems and researchers to better structure and design a public health approach to end-of-life care for people with dementia. DESIGN A realist review. Data sources MEDLINE, EMBASE, CINAHL and grey literature. ANALYSIS We conceptualised social capital as a complex intervention and, in order to understand how change is generated, used realist evaluation methods to create different configurations of context, mechanism and outcomes. We conducted an iterative search focusing on social capital, social networks and end-of-life care in dementia. All study designs and outcomes were screened and analysed to elicit explanations for a range of outcomes identified. Explanations were consolidated into an overarching programme theory that drew on substantive theory from the social sciences and a public health approach to palliative care. RESULTS We identified 118 articles from 16 countries ranging from 1992 to 2018. A total of 40 contextmechanism-outcome configurations help explain how social capital may influence end-of-life care for people with dementia. Such influence was identified within five key areas. These included: (1) socially orientating a person with dementia following diagnosis; (2) transitions in the physical environment of care; (3) how the caregiving experience is viewed by those directly involved with it; (4) transition of a person with dementia into the fourth age; (5) the decision making processes underpinning such processes. CONCLUSION This review contributes to the dispassionate understanding of how complex systems such as community and social capital might be viewed as a tool to improve end-of-life care for people with dementia. PROSPERO REGISTRATION NUMBER CRD42018084524

    Health Risk Screening and Counselling of Adolescents in Primary Care: a Cluster Randomised Controlled Trial

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    The research reported in this paper is a project of the Australian Primary Health Care Research Institute which is supported by a grant from the Australian Government Department of Health and Ageing under the Primary Health Care Research Evaluation and Development Strategy
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