4,356 research outputs found

    2020 NASA Technology Taxonomy: 2015 Technology Areas to 2020 Taxonomy Areas Crosswalk

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    To help users of the 2020 Taxonomy navigate changes from the 2015 Technology Area Breakdown Structure (TABS), this companion document provides a crosswalk between the 2015 Technology Areas (TAs) and the updated 2020 Taxonomy areas (TXs)

    Developing Flexible Discrete Event Simulation Models in an Uncertain Policy Environment

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    On February 1st, 2010 U.S. President Barack Obama submitted to Congress his proposed budget request for Fiscal Year 2011. This budget included significant changes to the National Aeronautics and Space Administration (NASA), including the proposed cancellation of the Constellation Program. This change proved to be controversial and Congressional approval of the program's official cancellation would take many months to complete. During this same period an end-to-end discrete event simulation (DES) model of Constellation operations was being built through the joint efforts of Productivity Apex Inc. (PAl) and Science Applications International Corporation (SAIC) teams under the guidance of NASA. The uncertainty in regards to the Constellation program presented a major challenge to the DES team, as to: continue the development of this program-of-record simulation, while at the same time remain prepared for possible changes to the program. This required the team to rethink how it would develop it's model and make it flexible enough to support possible future vehicles while at the same time be specific enough to support the program-of-record. This challenge was compounded by the fact that this model was being developed through the traditional DES process-orientation which lacked the flexibility of object-oriented approaches. The team met this challenge through significant pre-planning that led to the "modularization" of the model's structure by identifying what was generic, finding natural logic break points, and the standardization of interlogic numbering system. The outcome of this work resulted in a model that not only was ready to be easily modified to support any future rocket programs, but also a model that was extremely structured and organized in a way that facilitated rapid verification. This paper discusses in detail the process the team followed to build this model and the many advantages this method provides builders of traditional process-oriented discrete event simulations

    Technical assessment report on solar thermal energy use in cork industry : António Almeida - Cortiças S.A.

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    ABSTRACT: Nowadays, current industrial applications seek, whenever possible, to meet thermal needs on sustainable technologies that are economically viable and environmentally friendly. Despite the high potential, a number of challenges still have to be overcame. Those include maximum attainable temperatures, seasonal and daily transience in solar heat supply and its integration in the industrial processes (among others). For that purpose, the implementation of solar thermal energy into industrial applications has been recognised and addressed by IEA Solar Heating & Cooling Programme (established in 1977), in a number of different research studies, including those ones found in Task 33 and Task 49 (IEA, 2015a; IEA, 2015b; and IEA, 2016) supported by the International Energy Agency (IEA) agenda. In this area, a task called Solar Heat for Industrial Processes (SHIP) emerges, which suggested that solar thermal systems have a significant potential in the sector, even though in an early stage of progress. This activity was led primary by the Commonwealth Science and Industrial Research Organization (Fuller, 2011). General motivations to implement solar systems in cork industry include: i) economics, with respect to worldwide increasing gas prices, and ii) environmental, with respect to the carbon-dioxide footprint associated to this specific industrial sector. The main objective of this report is to assess the technical assessment of solar thermal use in the cork industry, more specifically in the António Almeida - Cortiças S.A., located in the north of Portugal. For that purpose, a close collaboration was establish with this industry through several activities namely: i) energetic audit and ii) different actions of monitoring and implementation of the Energy Consumption Rationalization Agreement (ECRA).N/

    Repeated stressors in adulthood increase the rate of biological ageing

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    Background Individuals of the same age can differ substantially in the degree to which they have accumulated tissue damage, akin to bodily wear and tear, from past experiences. This accumulated tissue damage reflects the individual’s biological age and may better predict physiological and behavioural performance than the individual‘s chronological age. However, at present it remains unclear how to reliably assess biological age in individual wild vertebrates. Methods We exposed hand-raised adult Eurasian blackbirds (Turdus merula) to a combination of repeated immune and disturbance stressors for over one year to determine the effects of chronic stress on potential biomarkers of biological ageing including telomere shortening, oxidative stress load, and glucocorticoid hormones. We also assessed general measures of individual condition including body mass and locomotor activity. Results By the end of the experiment, stress-exposed birds showed greater decreases in telomere lengths. Stress-exposed birds also maintained higher circulating levels of oxidative damage compared with control birds. Other potential biomarkers such as concentrations of antioxidants and glucocorticoid hormone traits showed greater resilience and did not differ significantly between treatment groups. Conclusions The current data demonstrate that repeated exposure to experimental stressors affects the rate of biological ageing in adult Eurasian blackbirds. Both telomeres and oxidative damage were affected by repeated stress exposure and thus can serve as blood-derived biomarkers of biological ageing.</p

    Global Voices on Campus: Why the Symposium Matters

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    https://ecommons.udayton.edu/global_voices_2/1004/thumbnail.jp

    Application of satellite images to locate and inventory vineyards in the designation of origin "Bierzo" in Spain

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    P. 277-290With a view to contributing to the improvement of the current vineyard registers, this study presents a methodology for vineyard mapping based on satellite remote sensing systems. The procedure was validated for the Designation of origin "Bierzo" in Spain. Different supervised classifications were performed besed on two Landsat images acquired in the same year. The objetives of the present study were to determine which classification yielded the best results and to quantify the influence of different factors that affected the overall classification accuracy, such as the resampling method, the use of georeferenced mosaics, or the combination of the two imagesS

    Hopping and crawling DNA-coated colloids

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    Understanding the motion of particles with ligand-receptors is important for biomedical applications and material design. Yet, even among a single design, the prototypical DNA-coated colloids, seemingly similar micrometric particles hop or roll, depending on the study. We shed light on this problem by observing DNA-coated colloids diffusing near surfaces coated with complementary strands for a wide array of coating designs. We find colloids rapidly switch between 2 modes: they hop - with long and fast steps - and crawl - with short and slow steps. Both modes occur at all temperatures around the melting point and over a wide array of designs. The particles become increasingly subdiffusive as temperature decreases, in line with subsequent velocity steps becoming increasingly anti-correlated. Overall, crawling (or hopping) phases are more predominant at low (or high) temperatures; crawling is also more efficient at low temperatures than hopping to cover large distances. We rationalize this behavior within a simple model: at lower temperatures, the number of bound strands increases, and detachment of all bonds is unlikely, hence, hopping is prevented and crawling favored. We thus reveal the mechanism behind a common design rule relying on increased strand density for long-range self-assembly: dense strands on surfaces are required to enable crawling, possibly facilitating particle rearrangements
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