2,357 research outputs found

    Analysis of regenerated single-shaft ceramic gas-turbine engines and resulting fuel economy in a compact car

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    Ranges in design and off-design operating conditions of an advanced gas turbine and their effects on fuel economy were analyzed. The assumed engine incorporated a single stage radial flow turbine and compressor with fixed geometry. Fuel economies were calculated over the composite driving cycle with gasoline as the fuel. At a constant turbine-inlet temperature, with a regenerator sized for a full power effectiveness the best fuel economies ranged from 11.1 to 10.2 km/liter (26.2 to 22.5 mpg) for full power turbine tip speeds of 770 to 488m/sec (2530 to 1600ft/sec), respectively

    On the theory of complex rays

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    The article surveys the application of complex-ray theory to the scalar Helmholtz equation in two dimensions. The first objective is to motivate a framework within which complex rays may be used to make predictions about wavefields in a wide variety of geometrical configurations. A crucial ingredient in this framework is the role played by Sp{} in determining the regions of existence of complex rays. The identification of the Stokes surfaces emerges as a key step in the approximation procedure, and this leads to the consideration of the many characterizations of Stokes surfaces, including the adaptation and application of recent developments in exponential asymptotics to the complex Wentzel--Kramers--Brilbuin expansion of these wavefields

    Representation in Children’s Literature: An Analysis of Disability in Picturebooks

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    In my project I will be analyzing how physical disabilities are portrayed in children’s literature. Specifically, I will be doing a content analysis of four picture-books that have won the Schneider Family award, which is given to books that embody the disability experience for child or adult audiences. Using the guided questions from the article “Beyond the Medal: Representations of Disability in Caldecott Winners,” I am going to determine if the characters with disabilities are portrayed in an ableist way. Appropriate representation is important for marginalized people, including people who have disabilities. Providing picturebooks that embrace disability rather than marginalize it has a positive impact on all children in a classroom. The goal of my project is to create an understanding of the importance of non-ableist representation of characters with disabilities in picturebooks. After using the article to analyze the picturebooks, I will use the picturebooks that represent disabilities in an appropriate way as the basis of lesson plans to use in an elementary school classroom. The lesson plans will be centered around the importance of inclusion and lead to a discussion with students about why it is important to learn about people that might be different from them. I hope that my lesson plans will be useful in my own future classrooms, and potentially the classrooms of other educators too

    Pedagogy of Teaching History: Comparing the Chronologic and Thematic Approaches

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    In Ferris Bueller’s Day Off, a monotone history teacher lectures in a room full of adolescents who show no interest at all in the topic. Unfortunately this is not an isolated instance of teaching history. History teachers are plagued with the stereotype of being dry and boring. While other contents adjust to accommodate students, the majority history tends to be taught in the typical fashion (Laufenberg, 2011, p. 1). A teacher lectures and students absorb information by taking notes. If students are really “lucky” there will be a break from lectures and instead will be able to enjoy a lengthy historical documentary. What can be done to change the ways that history can be taught? Perhaps the approach the teacher takes to teaching can impact the way students respond to the content. Classes typically taught with this lecture style tend to teach history as a timeline (Olson-Raymer, 2011). Teachers start with one event or date and move forward throughout history. An alternative approach further examined in this paper is a thematic approach where a teacher instead selects meaningful themes for students to explore in great detail. While other methods exist outside of these two approaches, the traditional chronological approach is contrasted to the thematic approach to determine if there are ways to alleviate the disinterest students have in history. Advantages, disadvantages and sample lesson plans are used to dissect these approaches to determine their effectiveness for use in the history classroom

    Comparison of laser speckle contrast imaging with laser Doppler for assessing microvascular function

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    Objective: To compare the inter-day reproducibility of post-occlusive reactive hyperaemia (PORH) and sympathetic vasomotor reflexes assessed by single-point laser Doppler flowmetry (SP-LDF), integrating-probe LDF (IP-LDF) and laser speckle contrast imaging (LSCI), and the spatial variability of PORH assessed by IP-LDF and LSCI. We also evaluated the relationship between IP-LDF and LSCI perfusion values across a broad range of skin blood flows. Methods: Eighteen healthy adults (50% male, age 27 ± 4 years) participated in this study. Using SP-LDF, IP-LDF and LSCI, an index of skin blood flow was measured on the forearm during PORH (1-, 5- and 10-min occlusions) and on the finger pad during inspiratory gasp and cold pressor tests. These tests were repeated 3-7 days later. Data were converted to cutaneous vascular conductance (CVC; laser Doppler flow/mean arterial pressure) and expressed as absolute and relative changes from pre-stimulus CVC (ΔCVCABS and ΔCVCREL, respectively), as well as normalised to peak CVC for the PORH tests. Reproducibility was expressed as within-subjects coefficients of variation (CV, in %) and intraclass correlation coefficients. Results: The reproducibility of PORH on the forearm was poorer when assessed with SP-LDF and IP-LDF compared to LSCI (e.g., CV for 5-min PORH ΔCVCABS = 35, 27 and 19%, respectively), with no superior method of data expression. In contrast, the reproducibility of the inspiratory gasp and cold pressor test responses on the finger pad were better with SP-LDF and IP-LDF compared to LSCI (e.g., CV for inspiratory gasp ΔCVCREL = 13, 7 and 19%, respectively). The spatial variability of PORH responses was poorer with IP-LDF compared to LSCI (e.g., CV ranging 11-35% versus 3-16%, respectively). The association between simultaneous LSCI and IP-LDF perfusion values was non-linear. Conclusion: The reproducibility of cutaneous PORH was better when assessed with LSCI compared to SP-LDF and IP-LDF; probably due to measuring larger skin areas (lower inter-site variability). However, when measuring sympathetic vasomotor reflexes on the finger pad, reproducibility was better with SP-LDF and IP-LDF, perhaps due to the high sensitivity of LSCI to changes in skin blood flow at low levels

    Downsizing assessment of automotive Stirling engines

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    A 67 kW (90 hp) Stirling engine design, sized for use in a 1984 1440 kg (3170 lb) automobile was the focal point for developing automotive Stirling engine technology. Since recent trends are towards lighter vehicles, an assessment was made of the applicability of the Stirling technology being developed for smaller, lower power engines. Using both the Philips scaling laws and a Lewis Research Center (Lewis) Stirling engine performance code, dimensional and performance characteristics were determined for a 26 kW (35 hp) and a 37 kW (50 hp) engine for use in a nominal 907 kg (2000 lb) vehicle. Key engine elements were sized and stressed and mechanical layouts were made to ensure mechanical fit and integrity of the engines. Fuel economy estimates indicated that the Stirling engine would maintain a 30 to 45 percent fuel economy advantage comparable spark ignition and diesel powered vehicles in the 1984 period

    Explicitly correlated plane waves: Accelerating convergence in periodic wavefunction expansions

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    We present an investigation into the use of an explicitly correlated plane wave basis for periodic wavefunction expansions at the level of second-order M{\o}ller-Plesset perturbation theory (MP2). The convergence of the electronic correlation energy with respect to the one-electron basis set is investigated and compared to conventional MP2 theory in a finite homogeneous electron gas model. In addition to the widely used Slater-type geminal correlation factor, we also derive and investigate a novel correlation factor that we term Yukawa-Coulomb. The Yukawa-Coulomb correlation factor is motivated by analytic results for two electrons in a box and allows for a further improved convergence of the correlation energies with respect to the employed basis set. We find the combination of the infinitely delocalized plane waves and local short-ranged geminals provides a complementary, and rapidly convergent basis for the description of periodic wavefunctions. We hope that this approach will expand the scope of discrete wavefunction expansions in periodic systems.Comment: 15 pages, 13 figure

    Conceptual design study for Infrared Limb Experiment (IRLE)

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    The phase A engineering design study for the Infrared Limb Experiment (IRLE) instrument, the infrared portion of the Mesosphere-Lower Thermosphere Explorer (MELTER) satellite payload is given. The IRLE instrument is a satellite instrument, based on the heritage of the Limb Infrared Monitor of the Stratosphere (LIMS) program, that will make global measurements of O3, CO2, NO, NO2, H2O, and OH from earth limb emissions. These measurements will be used to provide improved understanding of the photochemistry, radiation, dynamics, energetics, and transport phenomena in the lower thermosphere, mesosphere, and stratosphere. The IRLE instrument is the infrared portion of the MELTER satellite payload. MELTER is being proposed to NASA Goddard by a consortium consisting of the University of Michigan, University of Colorado and NASA Langley. It is proposed that the Space Dynamics Laboratory at Utah State University (SDL/USU) build the IRLE instrument for NASA Langley. MELTER is scheduled for launch in November 1994 into a sun-synchronous, 650-km circular orbit with an inclination angle of 97.8 deg and an ascending node at 3:00 p.m. local time
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