3,281 research outputs found

    Impedance-based arc fault determination device (IADD) and method

    Get PDF
    Embodiments according to the present invention provide an Impedance-based Arc-Fault Determination Device (IADD) and method that, when attached to an electrical node on the power system and through observations on voltage, current and phase shift with a step load change, determine the effective Thevenin equivalent circuit or Norton equivalent circuit at the point of test. The device and method determine the expected bolted fault current at the test location of interest, which enables calculation of incident energy and the assignment of a flash-hazard risk category

    Exploring issues of resilience and technology use for older people - A scoping review protocol

    Get PDF
    The aim of this scoping review is to understand the extent of issues of resilience implied by the interactions of older people with financial, social, and health related technologies. Older people aged 60+, technology use or non-use, and issues of resilience studied over the last four years (2019-2022) demarcate the scope of this review. Key exclusion criteria are older adults living in long-term care facilities, nursing homes, care homes and hospital in-patients. It also excludes studies on the perspectives of older peoples’ clinicians. The review will be carried out according to the Joanna Briggs Institute (JBI) scoping review methodology. The key information sources are SCOPUS, Web of Science, CINAHL, PsychINFO, and MEDLINE databases. The forms of grey literature included are reports from government and non-government organizations, as well as studies from the ProQuest Dissertations & Theses - Global database. The search is limited to studies written in English. For the first step in the search strategy, keywords and index terms will be identified via SCOPUS, Web of Science, and MEDLINE databases. This is followed by a search via the above databases. Third, a search of the reference lists of all included articles will form part of the full-text screening process. Two researchers will independently screen the titles and abstracts of the literature and then read the full text of the included literature, applying the inclusion criteria and searching reference lists. All data will be presented in tables and charts to answer the review question

    Models for Metal Hydride Particle Shape, Packing, and Heat Transfer

    Full text link
    A multiphysics modeling approach for heat conduction in metal hydride powders is presented, including particle shape distribution, size distribution, granular packing structure, and effective thermal conductivity. A statistical geometric model is presented that replicates features of particle size and shape distributions observed experimentally that result from cyclic hydride decreptitation. The quasi-static dense packing of a sample set of these particles is simulated via energy-based structural optimization methods. These particles jam (i.e., solidify) at a density (solid volume fraction) of 0.665+/-0.015 - higher than prior experimental estimates. Effective thermal conductivity of the jammed system is simulated and found to follow the behavior predicted by granular effective medium theory. Finally, a theory is presented that links the properties of bi-porous cohesive powders to the present systems based on recent experimental observations of jammed packings of fine powder. This theory produces quantitative experimental agreement with metal hydride powders of various compositions.Comment: 12 pages, 12 figures, 2 table

    DNA barcoding and integrative taxonomy of the heterolepisma sclerophylla species complex (Zygentoma: Lepismatidae: Heterolepismatinae) and the description of two new species

    Get PDF
    We present one of the first studies of DNA barcodes (COI sequences) in the basal insect order Zygentoma, and compare the data with nuclear (28S) and mitochondrial (16S) rDNA sequences and morphology for an integrative taxonomic study of the Heterolepisma sclerophylla Smith species group. DNA sequence analyses identified deep divisions between Queensland and New South Wales populations, and among populations in each state. Detailed morphological and morphometric evaluation of the specimens failed, in most cases, to identify unambiguous morphological characters of diagnostic value for each population, possibly due to the interaction of morphological conservatism with high levels of variability resulting from their continued moulting after reaching sexual maturity. Several strong consistent characters were identified to support the description of a southern Queensland population as a new species (Heterolepisma cooloola sp. nov.). The combined molecular and morphological data support the view that the presence of lanceolate scales and the absence of macrochaetae from the anterior margin of the frons are more significant to phylogeny than the arrangement of styli and the shape of the thoracic sternites in Heterolepisma. Specimens from Glen Davis, NSW, while indistinguishable from H. sclerophylla in all other characters examined, were found to possess one fewer pair of abdominal styli in both sexes and are also described as a new species (Heterolepisma coorongooba sp. nov.). Five lineages are recognized within the remaining NSW material but as reliable (non-overlapping) morphological and morphometric differences could not be identified, they are not described here as new species. Heterolepisma sclerophylla sensu stricto is considered to be a complex of morphologically ill-defined species or perhaps subspecies

    An Untriggered Search for Optical Bursts

    Full text link
    We present an untriggered search for optical bursts with the ROTSE-I telephoto array. Observations were taken which monitor an effective 256 square degree field continuously over 125 hours to m_{ROTSE}=15.7. The uniquely large field, moderate limiting magnitude and fast cadence of ∼\sim10 minutes permits transient searches in a new region of sensitivity. Our search reveals no candidate events. To quantify this result, we simulate potential optical bursts with peak magnitude, m_{p}, at t=10 s, which fade as f=(\frac{t}{t_{0}}) ^{\alpha_{t}}, where \alpha_t < 0. Simple estimates based on observational evidence indicate that a search of this sensitivity begins to probe the possible region occupied by GRB orphan afterglows. Our observing protocol and image sensitivity result in a broad region of high detection efficiency for light curves to the bright and slowly varying side of a boundary running from [\alpha_{t},m_{p}]=[-2.0,6.0] to [-0.3,13.2]. Within this region, the integrated rate of brief optical bursts is less than 1.1\times 10^{-8} {\rm s}^{-1} {\rm deg}^{-2}. At ∼\sim22 times the observed GRB rate from BATSE, this suggests a limit on \frac{\theta_{opt}}{\theta_{\gamma}}\lesssim 5 where \theta_{opt} and \theta_{\gamma} are the optical and gamma-ray collimation angles, respectively. Several effects might explain the absence of optical bursts, and a search of the kind described here but more sensitive by about 4 magnitudes should offer a more definitive probe.Comment: 8 pages, 6 figures, 1 tabl
    • …
    corecore