443 research outputs found

    The effects of localized damping on structural response

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    The effect of localized structural damping on the excitability of higher order normal modes of the large space telescope was investigated. A preprocessor computer program was developed to incorporate Voigt structural joint damping models in a NASTRAN finite-element dynamic model. A postprocessor computer program was developed to select critical modes for low-frequency attitude control problems and for higher frequency fine-stabilization problems. The mode selection is accomplished by ranking the flexible modes based on coefficients for rate gyro, position gyro, and optical sensors, and on image-plane motions due to sinusoidal or random power spectral density force and torque inputs

    Probabilistic computer model of optimal runway turnoffs

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    Landing delays are currently a problem at major air carrier airports and many forecasters agree that airport congestion will get worse by the end of the century. It is anticipated that some types of delays can be reduced by an efficient optimal runway exist system allowing increased approach volumes necessary at congested airports. A computerized Probabilistic Runway Turnoff Model which locates exits and defines path geometry for a selected maximum occupancy time appropriate for each TERPS aircraft category is defined. The model includes an algorithm for lateral ride comfort limits

    Calibración de sensores de humedad capacitivos usando redes neuronales

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    X Jornadas de Investigación de la Zona no Saturada del Suelo, Salamanca (España), 2011El estudio de la variabilidad espacial de la humedad del suelo a escala de parcela o cuenca agrícola requiere el uso de redes de sensores de humedad de bajo coste, que suelen mostrar una fiabilidad limitada y requieren de calibraciones específicas, especialmente en suelos con elevados contenidos en arcilla. El presente trabajo pretende plantear una calibración más fiable de sondas de humedad mediante un análisis mixto campo-laboratorio. Para la calibración de campo se dispone de datos gravimétricos; para la calibración en laboratorio se han usado columnas de suelo inalterado que tras ser saturadas fueron desecadas en un entorno controlado mientras se monitorizaba la evolución de su peso y la de su humedad volumétrica, medida con diferentes sondas capacitivas Decagon. Tras obtener curvas de secado y la relación entre la humedad gravimétrica y la volumétrica es posible realizar una calibración mejorada específica para cada tipo de suelo. Las redes neuronales son particularmente útiles para el modelado de procesos físicos y el ajuste de modelos. En este trabajo se propone el empleo de dichas herramientas para obtener calibraciones para las sondas analizadas en el tipo de suelo objeto de estudio. Los resultados muestran que dichas calibraciones permiten mejorar la precisión de las mediciones de humedad realizadas.The study of the spatial variability of soil water content at agricultural plot or catchment scales requires the use of low-cost soil water content sensor networks, which usually show a limited reliability and require specific calibrations, specially for soils with a high clay content. This work proposes a more reliable calibration of soil water content probes with a laboratory analysis. Minimally disturbed soil columns were saturated with water and dried in a controlled environment while monitorizing the evolution of their volumetric soil water content (with different capacitive Decagon Probes) and weights. After obtaining the drying curves and the relation between the volumetric and the measured gravimetric soil water contents it is possible to achieve an improved calibration specific for different kinds of soil. Neural networks are especially interesting for the modeling of physical processes and model adjustment. In this work, these tools were used in order to obtain improved calibrations for the analyzed probes in the studied soil type. Results show that this calibration improves the accuracy and pMinisterio de Ciencia e Innovación AGL2009 C03-03Junta de Andalucía AGR-478

    Measurement Properties of ID-PALL, A New Instrument for the Identification of Patients With General and Specialized Palliative Care Needs.

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    To improve access to palliative care, identification of patients in need of general or specialized palliative care is necessary. To our knowledge, no available identification instrument makes this distinction. ID-PALL is a screening instrument developed to differentiate between these patient groups. To assess the structural and criterion validity and the inter-rater agreement of ID-PALL. In this multicenter, prospective, cross-sectional study, nurses and physicians assessed medical patients hospitalized for 2 to 5 days in two tertiary hospitals in Switzerland using ID-PALL. For the criterion validity, these assessments were compared to a clinical gold standard evaluation performed by palliative care specialists. Structural validity, internal consistency and inter-rater agreement were assessed. 2232 patients were assessed between January and December 2018, 97% by nurses and 50% by physicians. The variances for ID-PALL G and S are explained by two factors, the first one explaining most of the variance in both cases. For ID-PALL G, sensitivity ranged between 0.80 and 0.87 and specificity between 0.56 and 0.59. ID-PALL S sensitivity ranged between 0.82 and 0.94, and specificity between 0.35 and 0.64. A cut-off value of 1 delivered the optimal values for patient identification. Cronbach's alpha was 0.78 for ID-PALL G and 0.67 for ID-PALL S. The agreement rate between nurses and physicians was 71.5% for ID-PALL G and 64.6% for ID-PALL S. ID-PALL is a promising screening instrument allowing the early identification of patients in need of general or specialized palliative care. It can be used by nurses and physicians without a specialized palliative care training. Further testing of the finalized clinical version appears warranted

    Some problems of the determination of best management practices to maintain the quality of agricultural soils

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    Póster presentado en la Conferencia ELS 2014, 22-25 Septiembre 2014, Bari, ItaliaIn spite of the great effort of scientific research exploring the influence of agricultural practices on soil quality, many aspects remain unclear, possibly precluding a more general adoption of the best management systems by farmers and land use planners. Among other causes of this knowledge gap, the wide variety of agricultural practices due to different climates, landforms, soils, and crop types make hard to find either a general best management system or at least common rules of larger applicability. Nevertheless the more important problem is that we usually consider soil as an invariant entity which does not change, or if it does, its changes are controlled. The purpose of this report is the discussion of the results of a meta-analysis of the effects of agricultural management practices on physical aspects of soil quality, throughout the published research data of countries of the central and western part of the European continent. Soil physical quality was evaluated through several indicators which were evaluated in the research reports found. The indicators were: bulk density, resistance to penetration, stability of aggregates, permeability and water and sediment yield. The results indicate that there are agricultural practices which could be classified as convenient, although their possible advantages are not always evident, as, for instance, direct drilling as compared to conventional tillage, where the farm operations induce a certain compaction not always alleviated in absence of tillage. To further explore some of the results, the evolution of some properties of a clay soil subject to a long term experiment in dry farming conditions in southern Spain is considered. The evolution of the soil properties must be taken into account, for a more precise evaluation of the efficiency of management practices

    Mechanism of polyubiquitination by human anaphase-promoting complex: RING repurposing for ubiquitin chain assembly.

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    Polyubiquitination by E2 and E3 enzymes is a predominant mechanism regulating protein function. Some RINGE3s, including anaphase-promoting complex/cyclosome (APC), catalyze polyubiquitination by sequential reactions with two different E2s. An initiating E2 ligates ubiquitin to an E3-bound substrate. Another E2 grows a polyubiquitin chain on the ubiquitin-primed substrate through poorly defined mechanisms. Here we show that human APC's RING domain is repurposed for dual functions in polyubiquitination. The canonical RING surface activates an initiating E2-ubiquitin intermediate for substrate modification. However, APC engages and activates its specialized ubiquitin chain-elongating E2 UBE2S in ways that differ from current paradigms. During chain assembly, a distinct APC11 RING surface helps deliver a substrate-linked ubiquitin to accept another ubiquitin from UBE2S. Our data define mechanisms of APC/UBE2S-mediated polyubiquitination, reveal diverse functions of RING E3s and E2s, and provide a framework for understanding distinctive RING E3 features specifying ubiquitin chain elongation

    Tests at 2K of the beta 0.35 spoke cryomodule prototype with the MTCA.4-based Low Level RF system prototype for the MYRRHA R&D

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    Within the framework of the first phase of MYRRHA (Multi-purpose hYbrid Research Reactor for High-tech Applications) project, called MINERVA, IJCLab was in charge of a fully equipped Spoke cryomodule prototype development, tested at 2K. It integrates two superconducting single spoke cavities, the RF power couplers and the Cold Tuning Systems associated. On the control side, a MTCA.4-based Low Level Radio Frequency (LLRF) system prototype and the Software/EPICS developments has been realized by IJCLab and the SCK CEN in collaboration with the company IOxOS Technologies. The final version of the global system and the results of the tests at 2K will show with some perspectives.Comment: Poster pr\'esent\'e au LLRF Workshop 2023 (LLRF2023, arXiv : 2310.03199
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