1,780 research outputs found

    Identification of cognitive factors related to remote work performance using closed circuit TV displays

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    Operator perceptual cognitive styles as predictors of remote task performance were identified. Remote tasks which require the use of servo controlled master/slave manipulators and closed circuit television for teleoperator repair and maintenance of nuclear fuel recycling systems are examined. A useful procedure for identifying such perceptual styles is described

    Man/machine interface development for the REMOTEX concept

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    The development of a man/machine interface system that can be used to remotely control a system composed of a transporter base and a force-reflecting, survocontrolled manipulator is reported. The concept features the incorporation of totally remote operation. A simulator is build to optimize man/machine interface requirements

    Generalization of the Kolmogorov-Sinai entropy: Logistic- and periodic-like maps at the chaos threshold

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    We numerically calculate, at the edge of chaos, the time evolution of the nonextensive entropic form Sq[1i=1Wpiq]/[q1]S_q \equiv [1-\sum_{i=1}^W p_i^q]/[q-1] (with S1=i=1WpilnpiS_1=-\sum_{i=1}^Wp_i \ln p_i) for two families of one-dimensional dissipative maps, namely a logistic- and a periodic-like with arbitrary inflexion zz at their maximum. At t=0t=0 we choose NN initial conditions inside one of the WW small windows in which the accessible phase space is partitioned; to neutralize large fluctuations we conveniently average over a large amount of initial windows. We verify that one and only one value q<1q^*<1 exists such that the limtlimWlimNSq(t)/t\lim_{t\to\infty} \lim_{W\to\infty} \lim_{N\to\infty} S_q(t)/t is {\it finite}, {\it thus generalizing the (ensemble version of) Kolmogorov-Sinai entropy} (which corresponds to q=1q^*=1 in the present formalism). This special, zz-dependent, value qq^* numerically coincides, {\it for both families of maps and all zz}, with the one previously found through two other independent procedures (sensitivity to the initial conditions and multifractal f(α)f(\alpha) function).Comment: 6 pages and 6 fig

    Use of fractal dimensions to quantify coral shape

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    A morphometrical method to quantify and characterize coral corallites using Richardson Plots and Kaye's notion of fractal dimensions is presented. A Jurassic coral species (Aplosmilia spinosa) and five Recent coral species were compared using the Box-Counting Method. This method enables the characterization of their morphologies at calicular and septal levels by their fractal dimensions (structural and textural). Moreover, it is possible to determine differences between species of Montastraea and to tackle the high phenotypic plasticity of Montastraea annularis. The use of fractal dimensions versus conventional methods (e.g., measurements of linear dimensions with a calliper, landmarks, Fourier analyses) to explore a rugged boundary object is discussed. It appears that fractal methods have the potential to considerably simplify the morphometrical and statistical approaches, and be a valuable addition to methods based on Euclidian geometr

    Ensemble averages and nonextensivity at the edge of chaos of one-dimensional maps

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    Ensemble averages of the sensitivity to initial conditions ξ(t)\xi(t) and the entropy production per unit time of a {\it new} family of one-dimensional dissipative maps, xt+1=1ae1/xtz(z>0)x_{t+1}=1-ae^{-1/|x_t|^z}(z>0), and of the known logistic-like maps, xt+1=1axtz(z>1)x_{t+1}=1-a|x_t|^z(z>1), are numerically studied, both for {\it strong} (Lyapunov exponent λ1>0\lambda_1>0) and {\it weak} (chaos threshold, i.e., λ1=0\lambda_1=0) chaotic cases. In all cases we verify that (i) both [lnqx(x1q1)/(1q);ln1x=lnx] [\ln_q x \equiv (x^{1-q}-1)/(1-q); \ln_1 x=\ln x] and <Sq>[Sq(1ipiq)/(q1);S1=ipilnpi]<S_q > [S_q \equiv (1-\sum_i p_i^q)/(q-1); S_1=-\sum_i p_i \ln p_i] {\it linearly} increase with time for (and only for) a special value of qq, qsenavq_{sen}^{av}, and (ii) the {\it slope} of andthatof and that of {\it coincide}, thus interestingly extending the well known Pesin theorem. For strong chaos, qsenav=1q_{sen}^{av}=1, whereas at the edge of chaos, qsenav(z)<1q_{sen}^{av}(z)<1.Comment: 5 pages, 5 figure

    Composición y calidad de la dieta del ciervo (Cervus elaphus L.) en el norte de la península ibérica

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    Plant composition and quality of the red deer (Cervus elaphus L.) diet in the northern Iberian peninsula The feeding pattern of red deer varies greatly among the different European populations. The aim of our study was to elucidate the plant composition and the quality of the red deer diet in the Pyrenees (Northern Iberian peninsula). Over a one-year period, the red deer fed mainly on browse, pines being the main food. However, unlike other populations on the Iberian peninsula, consumption of herbaceous plants was higher than browse in the spring-summer period. Nevertheless, the diet of Pyrenean red deer shared some features with the Mediterranean populations such as browsing on woody legumes. Fecal nitrogen content, as an index of diet quality, showed low annual values with a marked decrease in winter. The overall feeding pattern was similar to that of other Central European populations. The large size of the surveyed population probably affected its high level of browse consumption and poor quality diet

    Composición vegetal y calidad de la dieta del ciervo (Cervus elaphus L. ) en el norte de la península Ibérica

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    The feeding pattern of red deer varies greatly among the different European populations. The aim of our study was to elucidate the plant composition and the quality of the red deer diet in the Pyrenees (Northern Iberian peninsula). Over a one–year period, the red deer fed mainly on browse, pines being the main food. However, unlike other populations on the Iberian peninsula, consumption of herbaceous plants was higher than browse in the spring–summer period. Nevertheless, the diet of Pyrenean red deer shared some features with the Mediterranean populations such as browsing on woody legumes. Fecal nitrogen content, as an index of diet quality, showed low annual values with a marked decrease in winter. The overall feeding pattern was similar to that of other Central European populations. The large size of the surveyed population probably affected its high level of browse consumption and poor quality diet.El patrón de alimentación del ciervo es muy variable entre las diferentes poblaciones europeas. El objetivo de nuestro estudio fue determinar la composición vegetal y la calidad de la dieta del ciervo en los Pirineos (norte de la península Ibérica). Durante un periodo de un año, el ciervo se alimentó principalmente de plantas leñosas, siendo los pinos su principal alimento. Sin embargo a diferencia de otras poblaciones de la península Ibérica, el consumo de plantas herbáceas fue superior al de leñosas en primavera y verano. No obstante, la dieta del ciervo del Pirineo comparte algunas características con la de las poblaciones mediterráneas, como el consumo de plantas leguminosas leñosas. El contenido en nitrógeno fecal, como índice de calidad de la dieta, presenta valores anuales bajos con una marcada disminución en invierno. El patrón de alimentación global fue similar al de otras poblaciones centroeuropeas. El gran tamaño de la población estudiada influye probablemente en el alto nivel de consumo de leñosas y la baja calidad de su dieta
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