2,048 research outputs found

    On the prediction of critical flutter conditions from subcritical response data and some related wind-tunnel experience

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    Methods of interpreting response measurements which could be amenable to flight flutter testing procedures were studied analytically and in the wind tunnel. One suggested scheme, which requires evaluation, is an iterative technique in which derivatives obtained from subcritical response data are used to indicate the approach to flutter. A simplification of this procedure was considered by examining the manner in which a single characteristic of the subcritical response behaves in relation to variations of the density or dynamic pressure in the approach to flutter. The use of this single parameter scheme was examined for random excitation as well as for sinusoidal forcing. The feasibility of the method is illustrated by several examples and the relative merits of random and sinusoidal excitation are discussed

    Detailed requirements document for the integrated structural analysis system, phase B

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    The requirements are defined for a software system entitled integrated Structural Analysis System (ISAS) Phase B which is being developed to provide the user with a tool by which a complete and detailed analysis of a complex structural system can be performed. This software system will allow for automated interface with numerous structural analysis batch programs and for user interaction in the creation, selection, and validation of data. This system will include modifications to the 4 functions developed for ISAS, and the development of 25 new functions. The new functions are described

    Experimental and Analytical Investigation of the Transonic and Supersonic Divergence Characteristics of a Delta-Plan-Form All- Movable Control

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    The static aeroelastic divergence characteristics of a delta-planform model of the canard control surface of a proposed air-to-ground missile have been studied both analytically and experimentally in the Mach number range from 0.6 to 3.0. The experiments indicated that divergence occurred at a nearly constant value of dynamic pressure at Mach numbers up to 1.2. At higher Mach numbers somewhat higher values of dynamic pressure were required to produce divergence. The analysis and the experiment indicate that the camber stiffness of the control surface and the stiffness of the control actuator are both important in divergence of surfaces of this type

    Deep Learning Design for Social Innovation: Participatory Radio for Developing 21C Skills with Disenfranchised Learners

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    Deep Learning Design has been proposed as an approach to Technology Enhanced Learning (TEL) that foregrounds principles of learning and con-text over simply extrapolating the affordances of new technologies. An original application of this approach has been within contexts necessitating social innovation to promote the inclusion, non-formal learning and employability of disenfranchised learners across Europe – RadioActive101. This approach has actively developed, implemented and evaluated five radio hubs with at-risk young people and other disenfranchised groups to develop digital competencies and employability skills for the 21st Century. This Learning Design and associated competencies are mapped to a progression and accreditation model linking EU key competencies to RadioActive101 activities and performances that are recognised through open electronic 'badges'. Evaluation findings showed particularly positive results, and impact and value beyond the non-formal learning of technical and employability skills, such as improvements in confidence, self-esteem and general self-efficacy of individuals and organisational learning and development. We conclude this article by asking how and whether current approaches to learning design can accommodate such essential psychosocial dimensions of learning

    Defect Induced Ferromagnetism in Undoped ZnO Nanoparticles

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    Undoped ZnO nanoparticles (NPs) with size ∼12 nm were produced using forced hydrolysis methods using diethylene glycol (DEG) [called ZnO-I] or denatured ethanol [called ZnO-II] as the reaction solvent; both using Zn acetate dehydrate as precursor. Both samples showed weak ferromagnetic behavior at 300 K with saturation magnetization Ms = 0.077 ± 0.002 memu/g and 0.088 ± 0.013 memu/g for ZnO-I and ZnO-II samples, respectively. Fourier transform infrared(FTIR) spectra showed that ZnO-I nanocrystals had DEG fragments linked to their surface. Photoluminescence (PL) data showed a broad emission near 500 nm for ZnO-II which is absent in the ZnO-I samples, presumably due to the blocking of surface traps by the capping molecules. Intentional oxygen vacancies created in the ZnO-I NPs by annealing at 450 °C in flowing Ar gas gradually increased Ms up to 90 min and x-ray photoelectron spectra (XPS) suggested that oxygen vacancies may have a key role in the observed changes in Ms. Finally, PL spectra of ZnO showed the appearance of a blue/violet emission, attributed to Zn interstitials,whose intensity changes with annealing time, similar to the trend seen for Ms. The observed variation in the magnetization of ZnO NP with increasing Ar annealing time seems to depend on the changes in the number of Zn interstitials and oxygen vacancies

    The cell adhesion molecule Fasciclin2 regulates brush border length and organization in Drosophila renal tubules

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    Multicellular organisms rely on cell adhesion molecules to coordinate cell–cell interactions, and to provide navigational cues during tissue formation. In Drosophila, Fasciclin 2 (Fas2) has been intensively studied due to its role in nervous system development and maintenance; yet, Fas2 is most abundantly expressed in the adult renal (Malpighian) tubule rather than in neuronal tissues. The role Fas2 serves in this epithelium is unknown. Here we show that Fas2 is essential to brush border maintenance in renal tubules of Drosophila. Fas2 is dynamically expressed during tubule morphogenesis, localizing to the brush border whenever the tissue is transport competent. Genetic manipulations of Fas2 expression levels impact on both microvilli length and organization, which in turn dramatically affect stimulated rates of fluid secretion by the tissue. Consequently, we demonstrate a radically different role for this well-known cell adhesion molecule, and propose that Fas2-mediated intermicrovillar homophilic adhesion complexes help stabilize the brush border

    Arkansas Small-Grain Cultivar Performance tests 2008-2009

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    Small-grain cultivar performance tests are conducted each year in Arkansas by the Arkansas Agricultural Experiment Station, Department of Crop, Soil, and Environmental Sciences. The tests provide information to companies developing cultivars and/or marketing seed within the state and aid the Arkansas Cooperative Extension Service in formulating cultivar recommendations for smallgrain producers

    A fully integrated microfluidic device for point of care monitoring of antithrombotics

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    © 2016 The Royal Society of Chemistry. The simplicity and efficiency of point of care diagnostics have revolutionised patient care. Current methods for measuring hypercoagulability often require trained technicians, large blood volumes, and result in long turnaround times. Standard testing for hypercoagulable disorders is performed in the central laboratory using automated coagulation analysers. However the trend is moving towards the development and implementation of point of care testing, as a result of the ever increasing number of patients on antithrombotic therapy. We present a novel microfluidic device and assay for monitoring the effect of two anticoagulants, unfractionated heparin (UFH) and low molecular weight heparin (LMWH). The assay is based on the anti-Xa assay principle but uses fluorescence detection. Our device is a disposable laminate microfluidic strip, fabricated from the cyclic polyolefin (COP), Zeonor®, which is extremely suitable for application to fluorescent device platforms. We present data on the execution of the anti-Xa assay in this microfluidic format, demonstrating that the assay can be used to measure both UFH and LMWH in human plasma samples from 0 to 1 U mL-1, with a rapid result obtained within 30-60 seconds
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