91 research outputs found

    Taxonomy Induction using Hypernym Subsequences

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    We propose a novel, semi-supervised approach towards domain taxonomy induction from an input vocabulary of seed terms. Unlike all previous approaches, which typically extract direct hypernym edges for terms, our approach utilizes a novel probabilistic framework to extract hypernym subsequences. Taxonomy induction from extracted subsequences is cast as an instance of the minimumcost flow problem on a carefully designed directed graph. Through experiments, we demonstrate that our approach outperforms stateof- the-art taxonomy induction approaches across four languages. Importantly, we also show that our approach is robust to the presence of noise in the input vocabulary. To the best of our knowledge, no previous approaches have been empirically proven to manifest noise-robustness in the input vocabulary

    A design fuzzy logic controller for a permanent magnet wind generator to enhance the dynamic stability of wind farms

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    In this paper, a design fuzzy logic controller for a variable speed permanent magnet wind generator connected to a grid system through a LC-filter is proposed. A new current control method of grid side conversion is developed by integrating the fuzzy controller, in which both active and reactive power, delivered to a power grid system, is controlled effectively. The fuzzy logic controller is designed to adjust the gain parameters of the PI controllers under any operating conditions, so that the dynamic stability is enhanced. A new simple method, based on frequency response of the bode diagram, is proposed in the design of the fuzzy logic controller. To evaluate the controller system capabilities, simulation analyses are performed on a small wind farm model system including an induction wind generator connected to an infinite bus. The simulations have been performed using PSCAD/EMTDC. Simulation results show that the proposed control scheme is more effective for enhancing the stability of wind farms during temporary and permanent network disturbances and randomly fluctuating wind speed, compared with that of a conventional PI controller

    Safeguarding human–wildlife cooperation

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    Human–wildlife cooperation occurs when humans and free-living wild animals actively coordinate their behavior to achieve a mutually beneficial outcome. These interactions provide important benefits to both the human and wildlife communities involved, have wider impacts on the local ecosystem, and represent a unique intersection of human and animal cultures. The remaining active forms are human–honeyguide and human–dolphin cooperation, but these are at risk of joining several inactive forms (including human–wolf and human–orca cooperation). Human–wildlife cooperation faces a unique set of conservation challenges, as it requires multiple components—a motivated human and wildlife partner, a suitable environment, and compatible interspecies knowledge—which face threats from ecological and cultural changes. To safeguard human–wildlife cooperation, we recommend: (i) establishing ethically sound conservation strategies together with the participating human communities; (ii) conserving opportunities for human and wildlife participation; (iii) protecting suitable environments; (iv) facilitating cultural transmission of traditional knowledge; (v) accessibly archiving Indigenous and scientific knowledge; and (vi) conducting long-term empirical studies to better understand these interactions and identify threats. Tailored safeguarding plans are therefore necessary to protect these diverse and irreplaceable interactions. Broadly, our review highlights that efforts to conserve biological and cultural diversity should carefully consider interactions between human and animal cultures. Please see AfricanHoneyguides.com/abstract-translations for Kiswahili and Portuguese translations of the abstract

    Effects of larval growth condition and water availability on desiccation resistance and its physiological basis in adult Anopheles gambiae sensu stricto

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    <p>Abstract</p> <p>Background</p> <p>Natural populations of the malaria mosquito <it>Anopheles gambiae </it>s.s. are exposed to large seasonal and daily fluctuations in relative humidity and temperature, which makes coping with drought a crucial aspect of their ecology.</p> <p>Methods</p> <p>To better understand natural variation in desiccation resistance in this species, the effects of variation in larval food availability and access to water as an adult on subsequent phenotypic quality and desiccation resistance of adult females of the Mopti chromosomal form were tested experimentally.</p> <p>Results</p> <p>It was found that, under normal conditions, larval food availability and adult access to water had only small direct effects on female wet mass, dry mass, and water, glycogen and body lipid contents corrected for body size. In contrast, when females subsequently faced a strong desiccation challenge, larval food availability and adult access to water had strong carry-over effects on most measured physiological and metabolic parameters, and affected female survival. Glycogen and water content were the most used physiological reserves in relative terms, but their usage significantly depended on female phenotypic quality. Adult access to water significantly influenced the use of water and body lipid reserves, which subsequently affected desiccation resistance.</p> <p>Conclusions</p> <p>These results demonstrate the importance of growth conditions and water availability on adult physiological status and subsequent resistance to desiccation.</p

    A Model of Oxidative Stress Management: Moderation of Carbohydrate Metabolizing Enzymes in SOD1-Null Drosophila melanogaster

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    The response to oxidative stress involves numerous genes and mutations in these genes often manifest in pleiotropic ways that presumably reflect perturbations in ROS-mediated physiology. The Drosophila melanogaster SOD1-null allele (cSODn108) is proposed to result in oxidative stress by preventing superoxide breakdown. In SOD1-null flies, oxidative stress management is thought to be reliant on the glutathione-dependent antioxidants that utilize NADPH to cycle between reduced and oxidized form. Previous studies suggest that SOD1-null Drosophila rely on lipid catabolism for energy rather than carbohydrate metabolism. We tested these connections by comparing the activity of carbohydrate metabolizing enzymes, lipid and triglyceride concentration, and steady state NADPH:NADP+ in SOD1-null and control transgenic rescue flies. We find a negative shift in the activity of carbohydrate metabolizing enzymes in SOD1-nulls and the NADP+-reducing enzymes were found to have significantly lower activity than the other enzymes assayed. Little evidence for the catabolism of lipids as preferential energy source was found, as the concentration of lipids and triglycerides were not significantly lower in SOD1-nulls compared with controls. Using a starvation assay to impact lipids and triglycerides, we found that lipids were indeed depleted in both genotypes when under starvation stress, suggesting that oxidative damage was not preventing the catabolism of lipids in SOD1-null flies. Remarkably, SOD1-nulls were also found to be relatively resistant to starvation. Age profiles of enzyme activity, triglyceride and lipid concentration indicates that the trends observed are consistent over the average lifespan of the SOD1-nulls. Based on our results, we propose a model of physiological response in which organisms under oxidative stress limit the production of ROS through the down-regulation of carbohydrate metabolism in order to moderate the products exiting the electron transport chain

    Safeguarding human–wildlife cooperation

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    Human–wildlife cooperation occurs when humans and free-living wild animals actively coordinate their behavior to achieve a mutually beneficial outcome. These interactions provide important benefits to both the human and wildlife communities involved, have wider impacts on the local ecosystem, and represent a unique intersection of human and animal cultures. The remaining active forms are human–honeyguide and human–dolphin cooperation, but these are at risk of joining several inactive forms (including human–wolf and human–orca cooperation). Human–wildlife cooperation faces a unique set of conservation challenges, as it requires multiple components—a motivated human and wildlife partner, a suitable environment, and compatible interspecies knowledge—which face threats from ecological and cultural changes. To safeguard human–wildlife cooperation, we recommend: (i) establishing ethically sound conservation strategies together with the participating human communities; (ii) conserving opportunities for human and wildlife participation; (iii) protecting suitable environments; (iv) facilitating cultural transmission of traditional knowledge; (v) accessibly archiving Indigenous and scientific knowledge; and (vi) conducting long-term empirical studies to better understand these interactions and identify threats. Tailored safeguarding plans are therefore necessary to protect these diverse and irreplaceable interactions. Broadly, our review highlights that efforts to conserve biological and cultural diversity should carefully consider interactions between human and animal cultures

    Influence of process pressure on local facesheet instability for ultralight sandwich structures

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    The skin wrinkling phenomenon was investigated in case of ultralight sandwich structures with honeycomb core manufactured by one shot vacuum bag processing. A relation between process pressure and compressive strength of the skin was established

    Engineering and Informatics,

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    Abstract: This paper presents an effective and simple solution to the problem of Layer 3 (L3) handover in IEEE 802.11 wireless LANs (WLANs), so as to extend the IP mobility area of 802.11 wireless Stations (STAs). The IEEE 802.11f Inter-Access Point Protocol (IAPP), handles the Layer 2 (L2) mobility of STAs during L2 (intra-network) handovers, and offers IP connectivity via L2 specific methods. Instead of using a different protocol for the L3 mobility management of STAs, such as Mobile IP (MIP) [4] or a MIP-variant, the IAPP protocol is extended so as to also support the inter-network (L3) movements of 802.11 STAs. The proposed IAPP-based mechanism supports host mobility and offers substantial uninterrupted wireless IPconnectivity, even after L3 movements. The cornerstones of this mechanism are the zero-delay IP movement detection and the zero over-the-air IP signaling during IP handover establishment, which lead to seamless (very fast) and smooth IP handoffs. This fast IP-handoff method is especially suitable to 802.11 systems, as it has better performance than traditional MIP-based methods (shorter handover delays, near zero packet loss), while makes IP roaming transparent to the mobile STAs

    Damping of blade-shaft torsional oscillations of wind turbine generator system

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    In this article, the blade and shaft torsional oscillations of wind turbine generator system (WTGS) when a network disturbance occurs in the power system are analyzed. Several reports are available in the literature, where the damping of shaft torsional oscillations of steam turbine generator system is discussed. Though a huge number of wind generators are going to be connected with the existing network, the damping of blade-shaft torsional oscillations of WTGS has so far not been reported. In this work, for the damping of blade-shaft torsional oscillations of WTGS, the voltage source converter (VSC) based three-level STATCOM is proposed. The six-mass drive train model of WTGS is used for the sake of precise analysis. Moreover, the damping of blade-shaft torsional oscillations of WTGS by using pitch controller is analyzed also, since a pitch controller is attached with most of the recent wind turbines. Both symmetrical and unsymmetrical faults are considered as the network disturbances. Simulation results clearly show that the pitch controller can somewhat, and the STATCOM can significantly, decrease the blade and shaft torsional oscillations of WTGS, where the simulations have been done by PSCAD/EMTDC. Copyright © Taylor & Francis Group, LLC
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