4,461 research outputs found

    Tiltrotor CFD part II: aerodynamic optimisation of tiltrotor blades

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    This paper presents aerodynamic optimisation of tiltrotor blades with high-fidelity computational fluid dynamics. The employed optimisation framework is based on a quasi-Newton method, and the required high-fidelity flow gradients were computed using a discrete adjoint solver. Single-point optimisations were first performed, to highlight the contrasting requirements of the helicopter and aeroplane flight regimes. It is then shown how a trade-off blade design can be obtained using a multi-point optimisation strategy. The parametrisation of the blade shape allowed to modify the twist and chord distributions, and to introduce a swept tip. The work shows how these main blade shape parameters influence the optimal performance of the tiltrotor in helicopter and aeroplane modes, and how a compromise blade shape can increase the overall tiltrotor performance. Moreover, in all the presented cases, the accuracy of the adjoint gradients resulted in a small number of flow evaluations for finding the optimal solution, thus indicating gradient-based optimisation as a viable tool for modern tiltrotor design

    Provider Insight on Surmounting Specialty Practice Challenges to Improve Tdap Immunization Rates among Pregnant Women

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    Background Pertussis, or “whooping cough,” is an acute, contagious pulmonary disease that, despite being vaccine-preventable, has become an increasingly widespread problem in the United States. As a result, the Advisory Committee on Immunization Practices and American College of Obstetricians and Gynecologists updated recommendations stating clinicians should give a Tdap dose during every pregnancy, preferably at 27–36 weeks. Despite this recommendation, reported Tdap vaccine receipt rates during pregnancy vary from 16–61%, and previous studies have shown that clinician recommendation and vaccine administration are strongly associated with vaccine uptake among pregnant women. Methods Our aim was to inform new strategies to increase uptake of the Tdap vaccine among pregnant women and, ultimately, reduce pertussis-related morbidityand mortality in infants. We conducted interviewswith a sample of 24 ob-gyns. We subsequently performed grounded theory analyses of transcripts using deductive and inductive coding strategies followed by intercoder reliability assessment. Results All physicians interviewed were familiar with the most recent recommendation of giving the Tdap vaccine during the third trimester of every pregnancy, and the majority of physicians stated that they felt that the vaccine was important and effective due to the transfer of pertussis antibodies from the mother to the fetus. Most physicians indicated that they recommended the vaccine to patients during pregnancy, but not all reported administering it on site because it was not stocked at their practice. Implementation challenges for physicians included insurance reimbursement and other challenges (i.e., patient refusal). Tdap vaccinationduring pregnancy was a lower clinical priority for some physicians. Physicians recognized the benefits associated with Tdap vaccination during pregnancy. Conclusions Findings indicate while most ob-gyns recognize the benefits of Tdap and recommend vaccination during pregnancy, barriers such as insurance reimbursement and financial concerns for the practice can outweigh the perceived benefits. This resulted in some ob-gyns reporting choosing not to stock and administer the vaccine in their practice. Recommendations to address these concerns include 1) structural support for Tdap vaccine administration in ob-gyns practices; 2) Continuing medical education-equivalent educational interventions that address management techniques, vaccine coding, and other relevant information; and 3) interventions to assist physicians in communicating the importance of Tdap vaccination during pregnancy

    The integration of 'omic' disciplines and systems biology in cattle breeding

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    Enormous progress has been made in the selection of animals, including cattle, for specific traits using traditional quantitative genetics approaches. Nevertheless, considerable variation in phenotypes remains unexplained, and therefore represents potential additional gain for animal production. In addition, the paradigm shift in new disciplines now being applied to animal breeding represents a powerful opportunity to prise open the 'black box' underlying the response to selection and fully understand the genetic architecture controlling the traits of interest. A move away from traditional approaches of animal breeding toward systems approaches using integrative analysis of data from the 'omic' disciplines represents a multitude of exciting opportunities for animal breeding going forward as well as providing alternatives for overcoming some of the limitations of traditional approaches such as the expressed phenotype being an imperfect predictor of the individual's true genetic merit, or the phenotype being only expressed in one gender or late in the lifetime of an animal. This review aims to discuss these opportunities from the perspective of their potential application and contribution to cattle breeding. Harnessing the potential of this paradigm shift also poses some new challenges for animal scientists - and they will also be discussed

    Large-eddy simulation of the lid-driven cubic cavity flow by the spectral element method

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    This paper presents the large-eddy simulation of the lid-driven cubic cavity flow by the spectral element method (SEM) using the dynamic model. Two spectral filtering techniques suitable for these simulations have been implemented. Numerical results for Reynolds number Re=12000\text{Re}=12'000 are showing very good agreement with other experimental and DNS results found in the literature
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