5,520 research outputs found

    An investigation of the feasibility of improving oculometer data analysis through application of advanced statistical techniques

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    The data reduction capabilities of the current data reduction programs were assessed and a search for a more comprehensive system with higher data analytic capabilities was made. Results of the investigation are presented

    Magnetic avalanche-like behavior in disordered manganite (Eu0.4La0.1)(Sr0.4Ca0.1)MnO3

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    The half-doped manganite, (Eu0.4La0.1)(Sr0.4Ca0.1)MnO3, has been found to exhibit sharp step-like metamagnetic transitions below 5 K. The number of magnetic steps increases with decreasing temperature and this number suddenly rises from 3 at 2 K to ~50 at 1.7 K. The self-similar character of the multiple magnetic steps at reduced temperature identifies these steps as avalanche-like transitions. The occurrence of a multitude of magnetic steps at low temperatures, the decreasing effect of magnetic field sweep rate on the step-like metamagnetism, and the decreasing irreversibility of transition in the specific heat suggest that reduced spin-lattice coupling facilitates the transformation of antiferromagnetic to ferromagnetic state via an avalanche-like behavior.Comment: 13 pages, 5 Figure

    Direct correlation between 1/f magnetonoise and magnetoresistance in La<SUB>0.7</SUB>Sr<SUB>0.3</SUB>MnO<SUB>3</SUB> and (La<SUB>0.5</SUB>Pr<SUB>0.2</SUB>)Ba<SUB>0.3</SUB>MnO<SUB>3</SUB> manganites

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    Temperature- and magnetic-field-dependent electrical noise and electrical resistivity measurements were carried out on epitaxial thin films of a large bandwidth La0.7Sr0.3MnO3 and a disordered intermediate bandwidth (La0.5Pr0.2)Ba0.3MnO3 manganite system. The power spectral density was dominated by 1/f noise. This 1/f noise was observed to follow the overall temperature dependence of the resistivity. Moreover, in these compounds the magnetonoise effect was found to be of nearly the same magnitude as the magnetoresistance. This direct correlation between magnetonoise and magnetoresistance suggests that the enhanced 1/f noise has its origin in intrinsic charge-carrier density fluctuations

    Study of Dissipative Collisions of 20^{20}Ne (∼\sim7-11 MeV/nucleon) + 27^{27}Al

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    The inclusive energy distributions of complex fragments (3 ≤\leqZ ≤\leq 9) emitted in the reactions 20^{20}Ne (145, 158, 200, 218 MeV) + 27^{27}Al have been measured in the angular range 10o^{o} - 50o^{o}. The fusion-fission and the deep-inelastic components of the fragment yield have been extracted using multiple Gaussian functions from the experimental fragment energy spectra. The elemental yields of the fusion-fission component have been found to be fairly well exlained in the framework of standard statistical model. It is found that there is strong competition between the fusion-fission and the deep-inelastic processes at these energies. The time scale of the deep-inelastic process was estimated to be typically in the range of ∼\sim 10−21^{-21} - 10−22^{-22} sec., and it was found to decrease with increasing fragment mass. The angular momentum dissipations in fully energy damped deep-inelastic process have been estimated from the average energies of the deep-inelastic components of the fragment energy spectra. It has been found that, the estimated angular momentum dissipations, for lighter fragments in particular, are more than those predicted by the empirical sticking limit.Comment: 16 pages, 9 figure

    Power Grid Frequency Forecasting from μPMU Data using Hybrid Vector-Output LSTM network

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    The instantaneous balance of electrical supply and demand on the power grid is indicated by the power grid frequency, making it a pivotal variable for power system controls. Accurate frequency forecasting could enable new faster means of frequency management that enhance power system stability. A hybrid vector-output Long Short-Term Memory (LSTM) neural network has been studied using microsynchrophasor data to predict trajectories. The objective of this research is to evaluate the effectiveness of very short time horizon frequency prediction using this method. The proposed model has been trained with over and under-frequency operational limit excursion events as well as normal condition state, with the goal of minimising prediction errors. Training and testing have been conducted using 390,000 datapoints covering 65 frequency events obtained from a distribution grid connected solar farm in England. The results demonstrate this method can provide useful grid frequency projections and shed light on underlying behaviour. Index Terms—Electrical grid frequency, power system stability, time series forecasting, long short term memor
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