6,767 research outputs found

    Investigation of advanced counterrotation blade configuration concepts for high speed turboprop systems. Task 4: Advanced fan section aerodynamic analysis

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    The purpose of this study is the development of a three-dimensional Euler/Navier-Stokes flow analysis for fan section/engine geometries containing multiple blade rows and multiple spanwise flow splitters. An existing procedure developed by Dr. J. J. Adamczyk and associates and the NASA Lewis Research Center was modified to accept multiple spanwise splitter geometries and simulate engine core conditions. The procedure was also modified to allow coarse parallelization of the solution algorithm. This document is a final report outlining the development and techniques used in the procedure. The numerical solution is based upon a finite volume technique with a four stage Runge-Kutta time marching procedure. Numerical dissipation is used to gain solution stability but is reduced in viscous dominated flow regions. Local time stepping and implicit residual smoothing are used to increase the rate of convergence. Multiple blade row solutions are based upon the average-passage system of equations. The numerical solutions are performed on an H-type grid system, with meshes being generated by the system (TIGG3D) developed earlier under this contract. The grid generation scheme meets the average-passage requirement of maintaining a common axisymmetric mesh for each blade row grid. The analysis was run on several geometry configurations ranging from one to five blade rows and from one to four radial flow splitters. Pure internal flow solutions were obtained as well as solutions with flow about the cowl/nacelle and various engine core flow conditions. The efficiency of the solution procedure was shown to be the same as the original analysis

    Macroscale multimodal imaging reveals ancient painting production technology and the vogue in Greco-Roman Egypt.

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    Macroscale multimodal chemical imaging combining hyperspectral diffuse reflectance (400-2500 nm), luminescence (400-1000 nm), and X-ray fluorescence (XRF, 2 to 25 keV) data, is uniquely equipped for noninvasive characterization of heterogeneous complex systems such as paintings. Here we present the first application of multimodal chemical imaging to analyze the production technology of an 1,800-year-old painting and one of the oldest surviving encaustic ("burned in") paintings in the world. Co-registration of the data cubes from these three hyperspectral imaging modalities enabled the comparison of reflectance, luminescence, and XRF spectra at each pixel in the image for the entire painting. By comparing the molecular and elemental spectral signatures at each pixel, this fusion of the data allowed for a more thorough identification and mapping of the painting's constituent organic and inorganic materials, revealing key information on the selection of raw materials, production sequence and the fashion aesthetics and chemical arts practiced in Egypt in the second century AD

    Federal stimulus funds under the ARRA did not protect state student financial aid, further eroding higher education affordability

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    Recent years have seen large increases in the cost of a college degree, with higher education institutions becoming more reliant on tuition fees rather than state funding. Part of 2009’s American Recovery and Reinvestment Act had the aim of incentivizing states to spend more on higher education and to improve college affordability. Using a dataset spanning nine years and 50 states, Jennifer A. Delaney takes a close look at the policy’s effects. She finds that while states did not cut their appropriations for higher education, they do appear to have reduced student aid — a category of spending not specified in the legislation. She argues that if college is to remain affordable, future federal matching fund programs need to consider all types of state spending on higher education

    The importance of the electronic contribution to linear magnetoelectricity

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    We demonstrate that the electronic contribution to the linear magnetoelectric response, usually omitted in first-principles studies, can be comparable in magnitude to that mediated by lattice distortions, even for materials in which responses are strong. Using a self-consistent Zeeman response to an applied magnetic field for noncollinear electron spins, we show how electric polarization emerges in linear magnetoelectrics through both electronic- and lattice-mediated components -- in analogy with the high- and low-frequency dielectric response to an electric field. The approach we use is conceptually and computationally simple, and can be applied to study both linear and non-linear responses to magnetic fields.Comment: 5 pages, 3 figure

    Investigation of advanced counterrotation blade configuration concepts for high speed turboprop systems, task 1: Ducted propfan analysis

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    The time-dependent three-dimensional Euler equations of gas dynamics were solved numerically to study the steady compressible transonic flow about ducted propfan propulsion systems. Aerodynamic calculations were based on a four-stage Runge-Kutta time-marching finite volume solution technique with added numerical dissipation. An implicit residual smoothing operator was used to aid convergence. Two calculation grids were employed in this study. The first grid utilized an H-type mesh network with a branch cut opening to represent the axisymmetric cowl. The second grid utilized a multiple-block mesh system with a C-type grid about the cowl. The individual blocks were numerically coupled in the Euler solver. Grid systems were generated by a combined algebraic/elliptic algortihm developed specifically for ducted propfans. Numerical calculations were initially performed for unducted propfans to verify the accuracy of the three-dimensional Euler formulation. The Euler analyses were then applied for the calculation of ducted propfan flows, and predicted results were compared with experimental data for two cases. The three-dimensional Euler analyses displayed exceptional accuracy, although certain parameters were observed to be very sensitive to geometric deflections. Both solution schemes were found to be very robust and demonstrated nearly equal efficiency and accuracy, although it was observed that the multi-block C-grid formulation provided somewhat better resolution of the cowl leading edge region

    Identifying Collegiate Athlete\u27s Motivation to Continue Training in Quarantine Compared Between Sexes

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    Purpose: To identify the type of motivation that was most common among NCAA Division I athletes to continue training during a period of quarantine and how this differs between sexes. Methods: Male and female student-athletes from a university in the southern United States were recruited for the study. 47 participants (males = 13, females = 34) completed the Sport Motivation Scale-II (SMS-II) and Basic Needs Satisfaction in Sport Sale (BNSSS) questionnaire to determine their motivation and basic needs satisfaction during the period of imposed quarantine. Data Analysis: A Mann-Whitney-U test was calculated to determine the differences of composite intrinsic motivation and composite extrinsic motivation and subscales of BNSSS between sex. This was also used to examine the within-sex differences in composite motivation scores. Results: A total of 47 athletes completed the study. Both males and females reported statistically significant higher intrinsic motivation scores than extrinsic motivation scores on the SMS-II [(M: Intrinsic: 39.9 ± 18.0, Extrinsic: 22.2 ± 11.7; p = .003; d = 1.16) (F: Intrinsic: 42.2 ± 13.2, Extrinsic: 28.1 ± 11.7; p \u3c .001; d = 1.12)]. No other statistically significant differences were observed (P \u3e .05). Relatedness scored the highest for both males and females on the BNSSS. Conclusion: Collegiate athletes, regardless of sex, reported higher levels of intrinsic motivation than extrinsic, and scored satisfaction of relatedness the highest when reflecting on maintaining their sport training during quarantine
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