6,377 research outputs found

    On the trade-off between electrical power consumption and flight performance in fixed-wing UAV autopilots

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    This paper sets out a study of the autopilot design for fixed wing Unmanned Aerial Vehicles (UAVs) taking into account the aircraft stability, as well as the power consumption as a function of the selected control strategy. To provide some generality to the outcomes of this study, construction of a reference small-UAV model, based on averaging the main aircraft defining parameters, is proposed. Using such a reference model of small, fixed-wing UAVs, different control strategies are assessed, especially with a view towards enlarging the controllers' sampling time. A beneficial consequence of this sample time enlargement is that the clock rate of the UAV autopilots may be proportionally reduced. This reduction in turn leads directly to decreased electrical power consumption. Such energy saving becomes proportionally relevant as the size and power of the UAV decrease, with benefits of lengthening battery life and, therefore, the flight endurance. Additionally, through the averaged model, which is derived from both published data and computations made from actual data captured from real UAVs, it is shown that behavior predictions beyond that of any particular UAV model may be extrapolated.Peer ReviewedPostprint (author's final draft

    Distributional analyses in the picture-word interference paradigm: Exploring the semantic interference and the distractor frequency effects.

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    he present study explores the distributional features of two important effects within the picture-word interference paradigm: the semantic interference and the distractor frequency effects. These two effects display different and specific distributional profiles. Semantic interference appears greatly reduced in faster response times, while it reaches its full magnitude only in slower responses. This can be interpreted as a sign of fluctuant attentional efficiency in resolving response conflict. In contrast, the distractor frequency effect is mediated mainly by a distributional shift, with low frequency distractors uniformly shifting reaction times distribution towards a slower range of latencies. This finding fits with the idea that distractor frequency exerts its effect by modulating the point in time in which operations required to discard the distractor can start. Taken together, these results are congruent with current theoretical accounts of both the semantic interference and distractor frequency effects. Critically, distributional analyses highlight and further describe the different cognitive dynamics underlying these two effects, suggesting that this analytical tool is able to offer important insights about lexical access during speech productio

    The Manipulability Effect in Object Naming

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    Seeing objects triggers activation of motor areas. The implications of this motor activation in tasks that do not require object-use is still a matter of debate in cognitive sciences. Here we test whether motor activation percolates into the linguistic system by exploring the effect of object manipulability in a speech production task. Italian native speakers name the set of photographs provided by Gu\ue9rard, Lagac\ue8 and Brodeur (Beh Res Meth, 2015). Photographs varied on four motor dimensions concerning on how easily the represented objects can be grasped, moved, or pantomimed, and the number of actions that can be performed with them. The results show classical psycholinguistic phenomena such as the effect of age of acquisition and name agreement in naming latencies. Critically, linear mixed-effects models show an effect of three motor predictors over and above the psycholinguistic effects (replicating, in part, previous findings, Gu\ue9rard et al., 2015). Further research is needed to address how, and at which level, the manipulability effect emerges in the course of word production

    Local Government Actions to Prevent Childhood Obesity

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    Offers guidance on policy and programmatic actions local governments can take, with community input, to promote healthy eating and physical activity and to ensure equal opportunities for healthy living in low-income neighborhoods. Profiles best practices

    A Policy Switching Approach to Consolidating Load Shedding and Islanding Protection Schemes

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    In recent years there have been many improvements in the reliability of critical infrastructure systems. Despite these improvements, the power systems industry has seen relatively small advances in this regard. For instance, power quality deficiencies, a high number of localized contingencies, and large cascading outages are still too widespread. Though progress has been made in improving generation, transmission, and distribution infrastructure, remedial action schemes (RAS) remain non-standardized and are often not uniformly implemented across different utilities, ISOs, and RTOs. Traditionally, load shedding and islanding have been successful protection measures in restraining propagation of contingencies and large cascading outages. This paper proposes a novel, algorithmic approach to selecting RAS policies to optimize the operation of the power network during and after a contingency. Specifically, we use policy-switching to consolidate traditional load shedding and islanding schemes. In order to model and simulate the functionality of the proposed power systems protection algorithm, we conduct Monte-Carlo, time-domain simulations using Siemens PSS/E. The algorithm is tested via experiments on the IEEE-39 topology to demonstrate that the proposed approach achieves optimal power system performance during emergency situations, given a specific set of RAS policies.Comment: Full Paper Accepted to PSCC 2014 - IEEE Co-Sponsored Conference. 7 Pages, 2 Figures, 2 Table

    Working memory cross-modal binding and decoding ability in children in the first and second grades

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    The iconicity advantage in sign production: The case of bimodal bilinguals

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    Recent evidence demonstrates that pictures corresponding to iconic signs are named faster than pictures corresponding to non-iconic signs. The present study investigates the locus of the iconicity advantage in hearing bimodal bilinguals. A naming experiment with iconic and noniconic pictures in Italian Sign Language (LIS) was conducted. Bimodal bilinguals named the pictures either using a noun construction that involved the production of the sign corresponding to the picture or using a marked demonstrative pronoun construction replacing the picture sign. In this last condition, the pictures were colored and participants were instructed to name the pronoun together with the color. The iconicity advantage was reliable in the noun utterance but not in the marked demonstrative pronoun utterance. In a third condition, the colored pictures were presented as distractor stimuli and participants required to name the color. In this last condition, distractor pictures with iconic signs elicited faster naming latencies than non-iconic signs. The results suggest that the advantage of iconic signs in production arises at the level of semantic-tophonological links. In addition, we conclude that bimodal bilinguals and native signers do not differ in terms of the activation flow within the sign production system

    Nitrogen dynamics in field grown comice pears

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    Tesis para obtener el grado de Doctor of Philosophy (Ph.D.), de la Oregon State University, en mayo de 1990The dynamics of N was studied in field grown Comice/Provence quince BA29 pears in Medford, Oregon. Total tree biomass, N content, and ¹⁵N evaluations suggest that young pears require little N (48 kg N ha⁻¹ yr⁻¹). About 45% of total tree N present in dormant trees was remobilized into new growth the following season. Main storage organs were roots, frame and one-year wood. Before leaf fall, peripheral, medium and interior canopy leaves exported to storage tissues 71, 61 and 52% of their total N, respectively. The export of N was influenced more by leaf position in the canopy than the nutritional status of the tree. Shoot and fruit growth were dependent on newly absorbed N. A heavy crop load caused more stored N to be diverted into fruits at the expense of other tree components. Early spring application of N resulted in a buildup of tree reserves for developing buds, but produced excessive growth and resulted in fruits with undesirable high concentration of N. From harvest until leaf fall very little N was partitioned into the aerial portion of the tree. In order to increase sustantially N reserves in the aboveground structure of the tree, and avoid excessive shoot growth and high N fruits, N should be applied 3-6 weeks before harvest. When N was applied at or after harvest but before leaf fall, roots were primarily the site of N storage. At that time 5 or 10% postharvest urea spray was the only effective way to obtain labelled N in flower buds. Early spring growth normally depended on N reserves. However when temperature around bloom was warmer than the long term average newly absorbed N was translocated to the flowers. During the first 3-4 weeks after bloom newly absorbed N was partitioned to spur leaves while shoot leaves were more dependent on stored N. Once spur leaves reached full expansion N was diverted into shoot leaves and fruits. Fruits from the same tree varied considerable in N concentration especially when fertilizer N was applied after bloom. Trees with high N status discriminated in the allocation of N to fruit in different canopy positions but trees with low N status did not. Large number of fruits in any specific location lessened N concentrations. The location of the fruit in the canopy only partially explains N variability. Similar sized fruits only a few centimeters apart may have a two fold concentration range.EEA Alto ValleFil: Sanchez, Enrique Eduardo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Alto Valle; Argentin
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