7,383 research outputs found

    Input variable selection for forecasting models

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    2002 IFAC15th Triennial World Congress, Barcelona, SpainThe selection of input variables plays a crucial role when modelling time series. For nonlinear models there are not well developed techniques such as AIC and other criteria that work with linear models. In the case of Short Term Load Forecasting (STLF) generalization is greatly influenced by such selection. In this paper two approaches are compared using real data from a Spanish utility company. The models used are neural networks although the algorithms can be used with other nonlinear models. The experiments show that that input variable selection affects the performance of forecasting models and thus should be treated as a generalization problem

    A new concept of invariance for saturated systems

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    In this paper, a new concept of invariance for saturated linear systems is presented. This new notion of invariance, denoted SNS-invariance, has a number of geometrical properties that makes its use suitable for the estimation of the domain of attraction of saturated systems. The notion of SNS-domain of attraction, that serves as an estimation of the domain of attraction of a saturated system, is introduced. It is shown that, in case of single input saturated systems, any contractive set is contained in the SNS-domain of attraction. A simple algorithm that converges to the SNS-domain of attraction is presented. Some illustrative examples are given

    Effects of Participation in Inquiry Science Workshops and Follow-Up Activities on Middle School Science Teachers\u27 Content Knowledge, Teacher-Held Misconceptions, and Classroom Practices

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    An important aspect of developing science literacy for all students is developing science-literate teachers. With the implementation of the No Child Left Behind Act, many middle school teachers found themselves in a position where they were no longer qualified to teach middle school science. This study was designed to help science teachers increase their science content knowledge, identify and resolve misconceptions/errors they may have, and assist them in their teaching by providing strategies for inquiry-based teaching, science laboratory exercises, and science equipment. Teachers enrolled in biology courses offered by the Rocky Mountain Middle School Math and Science Partnership participated in this study. They were required to take pre-, post-, and follow-up assessments over course concepts, complete a survey over their background and teaching pedagogy, and be observed teaching in their classrooms for three class periods followed by an interview after each observation. The results included key findings: 1) These assessments indicated that science teachers can increase their science content knowledge by attending high-quality professional development courses designed to help increase basic science content knowledge on science content. 2) Teachers held numerous misconceptions as shown by the assessments and classroom observations. Some were resolved, some that appeared to be resolved at the time of the post test reappeared again on the follow-up test, and some were not resolved. 3) Teacher observations showed that they did use science equipment provided by the course instructors and they taught the content from the Biology course where appropriate. Teachers teaching classes other than biology demonstrated their ability to teach inquiry science by employing inquiry activities and teaching with a scientific method approach

    Invariants sets for a class of discrete-time lur'e Systems

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    16th IFAC World Congress. 03/07/2005. Praga (República Checa)We present a method to estimate the domain of attraction of a class of discrete-time Lur'e systems. A new notion of LNL-invariance, stronger than the traditional invariance concept, is introduced. An algorithm to determinate the largest LNL-invariant set for this class of systems is proposed. Moreover, it is proven that the LNL-invariant sets provided by this algorithm are polyhedral convex sets and constitute an estimation of the domain of attraction of the non-linear system

    Gestión e implementación de una pasarela HTTP-OPC aplicado a una planta solar

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    XXVI Jornadas de Automática, Alicante-Elche, 2005El propósito de este artículo es detallar cómo conseguir un acceso eficiente a datos provenientes de un dispositivo genérico o planta industrial situada dentro de una red local. Dicho dispositivo debe estar conectado a un servidor OPC que permita acceder a las distintas variables. La situación que se intenta resolver es aquella en la que solamente es posible acceder a las variables de un dispositivo cualquiera desde un equipo que esté necesariamente situado dentro de la misma red local. La solución abordada en este artículo se basa en la elaboración de una aplicación web que permita proporcionar el acceso a distintos usuarios tanto desde dentro como desde fuera de la red a la que pertenezca la planta. Esta solución permite también el control remoto ya sea de una planta industrial o cualquier otro tipo de dispositivo haciendo uso de OPC. En concreto, se mostrar´a una Planta Solar sobre la que se explicar´an los aspectos de implementación

    Evaluation of various tests for the diagnosis of soil contamination by 2,4,5 trichlorophenol (2,4,5-TCP).

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    The response of different types of soils to contamination with 2,4,5-triclorophenol was studied to test the validity of the concept of generic reference levels (GRL), the main criterion used to define soil contamination. Soil samples were artificially contaminated with doses of between 0 and 5000 mg kg-1of 2,4,5-triclorophenol, and analysed by various tests. Where possible, the response of soils to the contaminant was modelled by a sigmoidal dose-response curve in order to estimate the ED50 values. The tests provided different responses, but only microbial biomass-C and dehydrogenase and urease activities demonstrated soil deterioration in response to contamination. The results suggest that the diagnosis of soil contamination has been greatly simplified in the legislation by the provision of a single figure for each compound, and that the GRL concept could perhaps be substituted by measurement of ED50 values, which better reflect the alteration of a soil due to the presence of a xenobiotic substance.Peer reviewe

    Caracteres preimaginales y aspectos bionómicos de Gyriosomus luczotii Laporte, 1840 (Coleoptera, Tenebrionidae)

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    Se describe la morfología y microestructura coriónica del huevo y la morfología del primer estadio larvario de Gyriosomus luczotii Laporte, 1840 (Coleoptera, Tenebrionidae, Nycteliini). También se exponen antecedentes bionómicos y distribucionales de la especie. Para la obtención de huevos y larvas, se recolectaron parejas en el terreno que fueron mantenidas en cajas de cria hasta la ovoposición y posterior eclosión. La estructura y ornamentación del exocorion del huevo y características morfológicas externas de la larva fueron analizadas mediante microscopía electrónica de barrido. Los resultados muestran que los huevos de G. luczotii presentan un micropilo redondeado y exocorion liso, con células hexagonales sin aeropilos. Las larvas de G. luczotii presentan características morfológicas adaptativas para la vida edáfica del tipo Pedobionta: cápsula cefálica con gran cantidad de sensillas, patas protorácicas de función cavadora, y pigopodio bien desarrollado. Se analiza la importancia de algunos caracteres morfológicos de la larva de primer estadio como criterio de diagnóstico específico y se establece que las diferencias interespecíficas referidas a las sensillas frontales, la forma del clípeo y el margen anterior del labro tienen valor taxonómico y probablemente filogenético. Palabras clave: Tenebrionidae, Gyriosomus, Morfología, Estadios preimaginales, Desierto costero, Chile.Preimaginal characters and bionomical aspects of Gyriosomus luczotii Laporte, 1840 (Coleoptera, Tenebrionidae) We describe the morphology and microstructure of the egg chorion, and the morphology of the first instar larva of Gyriosomus luczotii Laporte, 1840 (Coleoptera, Tenebrionidae, Nycteliini). Bionomical and distributional data on this species are also provided. To obtain eggs and larvae, couples were collected in the field and kept in rearing cages until oviposture and ecclosion. The structure and adornment of the egg exochorion, and the exterior morphological features of larvae were examined with electron scanning microscopy. The eggs of G. luczotii showed a rounded micropyle and a smooth exochorion, composed of hexagonal cells without aeropyles. The larvae of G. luczotii showed morphological characteristics suited for an edaphic life similar to that of Pedobionta: digging prothoracic legs, cephalic capsule with abundant sensilla, and well–developed pygopodium. We analysed the importance of larval morphology as an element for specific diagnosis and found that interspecific differences regarding frontal sensilla, clypeus shape, and anterior part of labrum, had a taxonomic value and possibly a phylogenetic value. Key words: Tenebrionidae, Gyriosomus, Morphology, Preimaginal stages, Coastal desert, Chile.Se describe la morfología y microestructura coriónica del huevo y la morfología del primer estadio larvario de Gyriosomus luczotii Laporte, 1840 (Coleoptera, Tenebrionidae, Nycteliini). También se exponen antecedentes bionómicos y distribucionales de la especie. Para la obtención de huevos y larvas, se recolectaron parejas en el terreno que fueron mantenidas en cajas de cria hasta la ovoposición y posterior eclosión. La estructura y ornamentación del exocorion del huevo y características morfológicas externas de la larva fueron analizadas mediante microscopía electrónica de barrido. Los resultados muestran que los huevos de G. luczotii presentan un micropilo redondeado y exocorion liso, con células hexagonales sin aeropilos. Las larvas de G. luczotii presentan características morfológicas adaptativas para la vida edáfica del tipo Pedobionta: cápsula cefálica con gran cantidad de sensillas, patas protorácicas de función cavadora, y pigopodio bien desarrollado. Se analiza la importancia de algunos caracteres morfológicos de la larva de primer estadio como criterio de diagnóstico específico y se establece que las diferencias interespecíficas referidas a las sensillas frontales, la forma del clípeo y el margen anterior del labro tienen valor taxonómico y probablemente filogenético. Palabras clave: Tenebrionidae, Gyriosomus, Morfología, Estadios preimaginales, Desierto costero, Chile

    Is the Banana Ripe? Andean Bear–Human Conflict in a Protected Area of Colombia

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    The Andean bear (Tremarctos ornatus; bear) is endemic to the tropical Andes Mountains of South America. Previous assessments predict that bear populations will decline by \u3e30% in the next 30 years. The species may face the greatest threats within its historical distribution in Colombia where rapid agricultural expansion into natural habitats is increasing human–bear conflicts. Between April 2017 and March 2018, we studied bear feeding behavior on plantain (Musa sapientum) and banana (M. paradisiaca) crops within the Barbas-Bremen protected area in the central mountain range of Colombia to describe the magnitude of crop damage, economic losses, and spatial distribution of feeding sites where human–bear conflicts would most likely occur. We also identified all affected farmers and used structured interviews to determine their attitudes toward the bears and their conservation. We recorded 237 damaged plants and identified 57 bear feeding area locations on 9 farms. Bear damage consisted of bites to the trunk of each plant and consumption of the centers. The damage polygon covered 198 ha, and it was located in the northwestern portion of the protected area. Although we estimated that the magnitude of crop consumption by bears and social and economic dimensions of damage caused by the species in Colombia. Our research also provides insights on how human–bear conflicts may be mitigated in the study area

    Q fever mimicking herpetic encephalitis

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    We describe a patient with temporal lobe encephalitis associated with primary Coxiella burnetii infection who lsresented with CT and MRI findings suggestive of herpes simplex encephaktis and an initial improvement during treatment with acyclovir. Q fever should be considered in the differential diagnosis of patients whose manifestations suggest herpes encephalitis

    Ameliorative effects of salt resistance on physiological parameters in the halophyte Salicornia bigelovii torr. with plant growth-promoting rhizobacteria

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    Salicornia bigelovii is a promising resource to cultivate under extreme climatic conditions of arid-desert regions. However, the production of Salicornia depends on the appropriate supplementation of nitrogen rich synthetic fertilizers. Application of specific halotolerant nitrogen-fixing bacteria associated with S. bigelovii could be an important practice for crop production in salt-affected regions. Seedlings of S. bigelovii were inoculated and developed with plant growth promoting rhizobacteria (Klebsiella pnseumoniae) at different salinities (0 and 0.25 M NaCl) grown under in vitro conditions. The inoculation increased growth and physiological activity at a high salinity. The major benefits of inoculation were observed on total seedlings biomass (320 and 175 g at 0 and 0.25 M NaCl, respectively) and adjacent branches of stem biomass (150 and 85 g at 0 and 0.25 M NaCl, respectively). The inoculation with Klebsiella pneumoniae also significantly improved seedlings salinity tolerance compared to the noninoculated controls. In non-salinity conditions, the inoculated seedlings enhanced the CO2 fixation and O2 evolution. The non-inoculated controls were more sensitive to salinity than inoculated seedlings exposed to salinity, as indicated by several measured parameters. Moreover, inoculated seedlings had significantly increase on proline, phenolics content, but not significant in starch compared to noninoculated controls. In conclusion, K. pneumoniae inoculation mitigates the salinity effects and promotes the Salicornia growth.Keywords: Salicornia bigelovii, Klebsiella pneumoniae, halophyte, ecotype, stress salinity. African Journal of Biotechnology Vol. 12(34), pp. 5278-528
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