3,696 research outputs found

    An Intelligent Fuse-box for use with Renewable Energy Sources integrated within a Domestic Environment

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    This paper outlines a proposal for an intelligent fuse-box that can replace existing fuse-boxes in a domestic context such that a number of renewable energy sources can easily be integrated into the domestic power supply network, without the necessity for complex islanding and network protection. The approach allows intelligent control of both the generation of power and its supply to single or groups of electrical appliances. Energy storage can be implemented in such a scheme to even out the power supplied and simplify the control scheme required, and environmental monitoring and load analysis can help in automatically controlling the supply and demand profiles for optimum electrical and economic efficiency. Simulations of typical scenarios are carried out to illustrate the concept in operation

    A new species of Mayfly, Maccaffertium annae sp. n. (Ephemeroptera: Heptageniidae) from Mexican Amber (Miocene)

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    Maccaffertium annae sp. n. is described in the Mexican amber of early Miocene age. It constitutes the first species of mayfly (Ephemeroptera), the first record of the family Heptageniidae to be described from this amber, and also the first fossil record of the genus Maccaffertium. The species is represented by male and female imagos in one piece of amber

    Plant population dynamics under varying fire regimes

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    1987 Clinic Yearbook

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    The Clinic is the yearbook of the Sidney Kimmel Medical College (formerly Jefferson Medical College) at Thomas Jefferson University

    Embedding, quoting, or paraphrasing? Investigating the effects of political leaders' tweets in online news articles:The case of Donald Trump

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    Journalists frequently turn to Twitter for quotes from elite and non-elite sources to include within their online news articles. While recent research has found that including posts from ordinary people can influence news consumers' issue perceptions, there is limited research on the impact of including politicians' posts. We conduct two similar survey experiments, with Republican and Democrat respondents, to test the relative impact of including Donald Trump's tweets in a news article either in embedded format, quoted in plain text, or quoted in paraphrased format. Among Republicans, embedded tweets were unique in eliciting positive emotions which mediated higher ratings of Donald Trump's warmth and competence. Among Democrats, no significant differences were elicited by tweet format on perceptions of Trump. However, Democrats rated articles containing verbatim Trump tweets as significantly lower in journalistic quality. Results are discussed in relevance to journalist-politician power relations and perceptions of journalistic quality

    Efficient table-top dual-wavelength beamline for ultrafast transient absorption spectroscopy in the soft X-ray region.

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    We present a table-top beamline providing a soft X-ray supercontinuum extending up to 370 eV from high-order harmonic generation with sub-13 fs 1300 nm driving pulses and simultaneous production of sub-5 fs pulses centered at 800 nm. Optimization of high harmonic generation in a long and dense gas medium yields a photon flux of  ~ 1.4 Ă— 106 photons/s/1% bandwidth at 300 eV. The temporal resolution of X-ray transient absorption experiments with this beamline is measured to be 11 fs for 800 nm excitation. This dual-wavelength approach, combined with high flux and high spectral and temporal resolution soft X-ray absorption spectroscopy, is a new route to the study of ultrafast electronic dynamics in carbon-containing molecules and materials at the carbon K-edge

    Studies Towards the Synthesis of Popolohuanone E

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    The marine natural product Popolohuanone E has been the target for total synthesis. This C42 marine sponge metabolite, which contains two identical cis-decalin moieties, was first approached by a route starting from 3,4-dimethylcyclohex-2-enone via two stereospecific cuprate addition reactions. The known decalin (+/-)-3,4,4abeta,5,6,7,8,8a-octahydro-1beta-hydroxymethyl-5,6,8abeta-trimethyl-5beta-vinyl-2(1H)-naphthalenone was synthesised by this route and subsequent elaboration carried out. After deoxygenation of the carbonyl group and further manipulation, the novel aldehyde, (+/-)-1,2,3,4,4abeta,5,6,7,8,8a-decahydro-1beta-tert-butyldimethylsilyloxymethyl-5,6,8abeta-trimethyl-5beta-formyl naphthalene, was obtained. Further elaboration of the aldehyde to the pseudo-monomeric carbon skeleton of popolohuanone E was not possible. Secondly a new route to the cis-decalin moiety was attempted. This involved synthesis of 1-iodo-3,4-dimethyl-6-trimethylsilylhex-4-ene from tiglic aldehyde by a route involving an Eschenmoser-Claisen rearrangement. Unfortunately due to time constraints the coupling of this iodide with the ketal of 2-bromo-l-cyclohex-2-enone and the subsequent intramolecular Hosomi-Sakurai cyclization were not accomplished. Finally attention was turned to developing a reliable route to the pseudo-monomer utilising a benzylic cuprate addition. Even after extensive experimentation with various enones, the desired adducts proved to be elusive

    Optimizing the Jiles-Atherton Model of Hysteresis by a genetic algorithm

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    Modeling magnetic components for simulation in electric circuits requires an accurate model of the hysteresis loop of the core material used. It is important that the parameters extracted for the hysteresis model be optimized across the range of operating conditions that may occur in circuit simulation. This paper shows how to extract optimal parameters for the Jiles-Atherton model of hysteresis by the genetic algorithm approach. It compares performance with the well-known simulated annealing method and demonstrates that improved results may be obtained with the genetic algorithm. It also shows that a combination of the genetic algorithm and the simulated annealing method can provide an even more accurate solution that either method on its own. A statistical analysis shows that the optimization obtained by the genetic algorithm is better on average, not just on a one-off test basis. The paper introduces and applies the concept of simultaneous optimization for major and minor hysteresis loops to ensure accurate model optimization over a wide variety of operating conditions. It proposes a modification to the Jiles-Atherton model to allow improved accuracy in the modeling of the major loop
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