351 research outputs found

    Computer analysis of wing design for general aviation aircraft

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    The calculation of the two dimensional viscous incompressible flow about single and multielement aerofoil sections is considered. A panel method, based on vorticity and source distributions is used for the calculation of the potential flow. Once the velocity distribution is known, integral boundary layer methods are employed to predict the viscous effects. A wake model has also been developed for the calculation of the wake behind the aerofoil system. The solution is iterative. At the end of each iteration the velocities on the aerofoil are corrected for viscosity and wake effects; the wake position is also relaxed, before the next iteration starts. The mathematical model of the flow, together with the computer program written to test the model are described here in detail. The numerical results obtained using the computer program are found to be in good agreement with both experimental data and exact solutions

    Collection Efficiency and Ice Accretion Characteristics of Two Full Scale and One 1/4 Scale Business Jet Horizontal Tails

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    Collection efficiency and ice accretion calculations have been made for a series of business jet horizontal tail configurations using a three-dimensional panel code, an adaptive grid code, and the NASA Glenn LEWICE3D grid based ice accretion code. The horizontal tail models included two full scale wing tips and a 25 percent scale model. Flow solutions for the horizontal tails were generated using the PMARC panel code. Grids used in the ice accretion calculations were generated using the adaptive grid code ICEGRID. The LEWICE3D grid based ice accretion program was used to calculate impingement efficiency and ice shapes. Ice shapes typifying rime and mixed icing conditions were generated for a 30 minute hold condition. All calculations were performed on an SGI Octane computer. The results have been compared to experimental flow and impingement data. In general, the calculated flow and collection efficiencies compared well with experiment, and the ice shapes appeared representative of the rime and mixed icing conditions for which they were calculated

    Development of a combined surface plasmon resonance/surface acoustic wave device for the characterization of biomolecules

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    It is known that acoustic sensor devices, if operated in liquid phase, are sensitive not just to the mass of the analyte but also to various other parameters, such as size, shape, charge and elastic constants of the analyte as well as bound and viscously entrained water. This can be used to extract valuable information about a biomolecule, particularly if the acoustic device is combined with another sensor element which is sensitive to the mass or amount of analyte only. The latter is true in good approximation for various optical sensor techniques. This work reports on the development of a combined surface plasmon resonance/surface acoustic wave sensor system which is designed for the investigation of biomolecules such as proteins or DNA. Results for the deposition of neutravidin and DNA are reported

    GOES-R Algorithms: A Common Science and Engineering Design and Development Approach for Delivering Next Generation Environmental Data Products

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    GOES-R, the next generation of the National Oceanic and Atmospheric Administration’s (NOAA) Geostationary Operational Environmental Satellite (GOES) System, represents a new technological era in operational geostationary environmental satellite systems. GOES-R will provide advanced products that describe the state of the atmosphere, land, oceans, and solar/ space environments over the western hemisphere. The Harris GOES-R Ground Segment team will provide the software, based on government-supplied algorithms, and engineering infrastructures designed to produce and distribute these next-generation data products. The Harris GOES-R Team has adopted an integrated applied science and engineering approach that combines rigorous system engineering methods, with modern software design elements to facilitate the transition of algorithms for Level 1 and 2+ products to operational software. The Harris Team GOES-R GS algorithm framework, which includes a common data model interface, provides general design principles and standardized methods for developing general algorithm services, interfacing to external data, generating intermediate and L1b and L2 products and implementing common algorithm features such as metadata generation and error handling. This work presents the suite of GOES-R products, their properties and the process by which the related requirements are maintained during the complete design/development life-cycle. It also describes the algorithm architecture/engineering approach that will be used to deploy these algorithms, and provides a preliminary implementation road map for the development of the GOES-R GS software infrastructure, and a view into the integration of the framework and data model into the final design

    Reality Check of Laboratory Service Effectiveness during Pandemic (H1N1) 2009, Victoria, Australia

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    TOC summary: The greatest challenges were insufficient staff and test reagents

    Identifying Misinformation on YouTube through Transcript Contextual Analysis with Transformer Models

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    Misinformation on YouTube is a significant concern, necessitating robust detection strategies. In this paper, we introduce a novel methodology for video classification, focusing on the veracity of the content. We convert the conventional video classification task into a text classification task by leveraging the textual content derived from the video transcripts. We employ advanced machine learning techniques like transfer learning to solve the classification challenge. Our approach incorporates two forms of transfer learning: (a) fine-tuning base transformer models such as BERT, RoBERTa, and ELECTRA, and (b) few-shot learning using sentence-transformers MPNet and RoBERTa-large. We apply the trained models to three datasets: (a) YouTube Vaccine-misinformation related videos, (b) YouTube Pseudoscience videos, and (c) Fake-News dataset (a collection of articles). Including the Fake-News dataset extended the evaluation of our approach beyond YouTube videos. Using these datasets, we evaluated the models distinguishing valid information from misinformation. The fine-tuned models yielded Matthews Correlation Coefficient>0.81, accuracy>0.90, and F1 score>0.90 in two of three datasets. Interestingly, the few-shot models outperformed the fine-tuned ones by 20% in both Accuracy and F1 score for the YouTube Pseudoscience dataset, highlighting the potential utility of this approach -- especially in the context of limited training data

    Pathophysiology and Biomechanics of the Aging Spine

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    Aging of the spine is characterized by two parallel but independent processes: the reduction of bone mineral density and the development of degenerative changes. The combination of degeneration and bone mass reduction contribute, to a different degree, to the development of a variety of lesions. This results in a number of painful and often debilitating disorders. The present review constitutes a synopsis of the pathophysiological processes that take place in the aging spine as well as of the consequences these changes have on the biomechanics of the spine. The authors hope to present a thorough yet brief overview of the process of aging of the human spine

    Serous labyrinthitis as a manifestation of cat scratch disease: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Cat scratch disease is an infectious disease transmitted by young cats, in which the principal causative factor is <it>Bartonella henselae</it>. The typical course of cat scratch disease is usually benign and self-limited and requires only supportive therapy. However, cases lasting up to 2 years have been reported, and more serious complications may occur. Many manifestations of the disease have been reported by different medical disciplines.</p> <p>Case presentation</p> <p>A case of cat scratch disease in a 71-year-old Greek woman with an unusual clinical course is presented here. Serous otitis media was combined with rotational vertigo due to labyrinthitis. The invaded ear was ipsilateral to the inoculation site.</p> <p>Conclusion</p> <p>Cervicofacial lymphadenopathy has been demonstrated as the most common otolaryngologic manifestation of cat scratch disease. Manifestation in the middle and inner ear has, to the best of our knowledge, not been reported before. Our report presents a patient with cat scratch disease with clinical signs and symptoms in the middle and inner ear.</p

    Design rules for active control of narrowband thermal emission using phase-change materials

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    We propose an analytical framework to design actively tunable narrowband thermal emitters at infrared frequencies. We exemplify the proposed design rules using phase-change materials (PCM), considering dielectric-to-dielectric PCMs (e.g. GSST) and dielectric-to-metal PCMs (e.g. VO2\mathrm{VO_2}). Based on these, we numerically illustrate near-unity ON-OFF switching and arbitrarily large spectral shifting between two emission wavelengths, respectively. The proposed systems are lithography-free and consist of one or several thin emitter layers, a spacer layer which includes the PCM, and a back reflector. Our model applies to normal incidence, though we show that the behavior is essentially angle-independent. The presented formalism is general and can be extended to \textit{any} mechanism that modifies the optical properties of a material, such as electrostatic gating or thermo-optical modulation.Comment: 9 pages, 6 figure

    Hypertrophic cardiomyopathy and ultra-endurance running - two incompatible entities?

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    Regular and prolonged exercise is associated with increased left ventricular wall thickness that can overlap with hypertrophic cardiomyopathy (HCM). Differentiating physiological from pathological hypertrophy has important implications, since HCM is the commonest cause of exercise-related sudden cardiac death in young individuals. Most deaths have been reported in intermittent 'start-stop' sports such as football (soccer) and basketball. The theory is that individuals with HCM are unable to augment stroke volume sufficiently to meet the demands of endurance sports and are accordingly 'selected-out' of participation in such events. We report the case of an ultra-endurance athlete with 25 years of > 50 km competitive running experience, with genetically confirmed HCM; thereby demonstrating that these can be two compatible entities
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