10,441 research outputs found

    Laminar boundary-layer heat transfer from a partially-ionized monatomic gas by the similarity approach

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    Laminar boundary layer heat transfer from ionized monatomic gas to wind tunnel wal

    Equine digital tendons show breed‐specific differences in their mechanical properties that may relate to athletic ability and predisposition to injury

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    Background Throughout the ages, human subjects have selected horse breeds for their locomotor capacities. Concurrently, tissue properties may have diversified because of specific requirements of different disciplines. Objectives The aim of this study was to compare the biomechanical properties of tendons with different functions between equine breeds traditionally selected for racing or sport. Study design This study used ex vivo tendons and compared the mechanical properties of the common digital extensor tendon (CDET) and superficial digital flexor tendon (SDFT) between racehorses (Thoroughbred [TB]) and sports horses (Friesian Horse [FH], Warmblood [WB]). Methods The SDFT and CDET of FH (n = 12), WBs (n = 12) and TBs (n = 8) aged 3-12 years were harvested. The cross sectional area (cm(2)), maximal load (N), ultimate strain (%), ultimate stress (MPa) and elastic modulus (MPa) were determined and tested for significant differences between the breeds (P<0.05). Results The SDFT from WB horses had a significantly lower elastic modulus than TB horses and failed at a higher strain and load than both FHs and TBs. The mechanical properties of the CDET did not differ between breeds. In agreement with previous studies, the CDET failed at a higher stress and had a higher elastic modulus than the SDFT and, for the WB group of horses only, failed at a significantly lower strain. Interestingly, the mode of failure differed between breeds, particularly with respect to the FHs. Main limitations The exercise history of horses used in this study was unknown and the age-range was relatively large; both these factors may have influenced the absolute properties reported in this study. Conclusions This study shows for the first time that mechanical properties of the SDFT differ between breeds. These properties are likely to be related to selection for high-speed vs. an extravagant elastic gait and may be an important indicator of performance ability. The is available in Spanish - see Supporting Informatio

    Convective heat transfer in a convergent- divergent nozzle

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    Turbulent flow convective heat transfer in convergent-divergent nozzle

    Explosive propulsion applications

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    The feasibility and application of an explosive propulsion concept capable of supporting future unmanned missions in the post-1980 era were examined and recommendations made for advanced technology development tasks. The Venus large lander mission was selected as the first in which the explosive propulsion concept can find application. A conceptual design was generated and its performance, weight, costs, and interaction effects determined. Comparisons were made with conventional propulsion alternatives. The feasibility of the explosive propulsion system was verified for planetology experiments within the dense atmosphere of Venus as well as the outer planets. Additionally, it was determined that the Venus large lander mission could be augmented ballistically with a significant delivery margin

    Fundamental study of flow field generated by rotorcraft blades using wide-field shadowgraph

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    The vortex trajectory and vortex wake generated by helicopter rotors are visualized using a wide-field shadowgraph technique. Use of a retro-reflective Scotchlite screen makes it possible to investigate the flow field generated by full-scale rotors. Tip vortex trajectories are visible in shadowgraphs for a range of tip Mach number of 0.38 to 0.60. The effect of the angle of attack is substantial. At an angle of attack greater than 8 degrees, the visibility of the vortex core is significant even at relatively low tip Mach numbers. The theoretical analysis of the sensitivity is carried out for a rotating blade. This analysis demonstrates that the sensitivity decreases with increasing dimensionless core radius and increases with increasing tip Mach number. The threshold value of the sensitivity is found to be 0.0015, below which the vortex core is not visible and above which it is visible. The effect of the optical path length is also discussed. Based on this investigation, it is concluded that the application of this wide-field shadowgraph technique to a large wind tunnel test should be feasible. In addition, two simultaneous shadowgraph views would allow three-dimensional reconstruction of vortex trajectories

    High pTp_{T} Inclusive Charged Hadron Spectra from Au+Au Collisions at sNN\sqrt{s_{NN}} = 200 GeV

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    The STAR Collaboration presents new measurements of inclusive charged hadron distributions for pT<p_{T} < 12 GeV/c from Au+Au collisions at sNN\sqrt{s_{NN}} = 200 GeV. Charged hadron suppression at high pTp_{T} is similar in shape and magnitude at all centralities to that observed previously at sNN\sqrt{s_{NN}} = 130 GeV for pT<p_{T} < 6 GeV/c. The ratio of spectra from central and peripheral Au+Au collisions shows that hadron suppression is approximately constant within 6 <pT<< p_{T} < 12 GeV/c. The ratios of charged hadron spectra at the two beam energies show a 15-20% increase in yield at low pTp_{T}. At high pTp_{T}, the ratios show a larger increase that agrees well with pQCD calculations of the sNN\sqrt{s_{NN}} dependence of particle production in Au+Au collisions.Comment: 4 pages, 4 figures, Quark Matter 2002 Proceeding

    Field Work Reflections: Journeys in Knowing and Not-Knowing

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    In this paper, I retrace my interest in narrative forms of inquiry. I begin by revisiting a series of research projects that I conducted early in my career, describing some of my own dissatisfactions with the methods I used at the time. I move on to a detailed reexamination of my first piece of narrative research, completed during my PhD. In that project I used a narrative pointed psychosocial method in an attempt to develop new knowledge in the field of drugs, ‘race’ and ethnicity. In the final section, I consider what I have learned from this approach in terms of knowing and not-knowing and how I have used this experience to explore different approaches to narrative inquiry. I finish by drawing out some lessons I have learned from these different studies, which I hope might be of relevance to other social work researchers
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