5,674 research outputs found

    Learning guide for the terminal configured vehicle advanced guidance and control system mode select panel

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    This learning guide is designed to assist pilots in taking the PLATO presimulator training course on the advanced guidance and control system mode select panel. The learning guide is divided into five sections. The first section, the introduction, presents the course goals, prerequisites, definition of PLATO activities, and a suggested approach to completing the course. The remaining four sections present the purpose, learning activities and summary of each lesson of the AGCS PLATO course, which consists of (1) AGCS introduction; (2) lower order modes; (3) higher order modes; and (4) an arrival route exercise

    Solar Cell Light Trapping beyond the Ray Optic Limit

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    In 1982, Yablonovitch proposed a thermodynamic limit on light trapping within homogeneous semiconductor slabs, which implied a minimum thickness needed to fully absorb the solar spectrum. However, this limit is valid for geometrical optics but not for a new generation of subwavelength solar absorbers such as ultrathin or inhomogeneously structured cells, wire-based cells, photonic crystal-based cells, and plasmonic cells. Here we show that the key to exceeding the conventional ray optic or so-called ergodic light trapping limit is in designing an elevated local density of optical states (LDOS) for the absorber. Moreover, for any semiconductor we show that it is always possible to exceed the ray optic light trapping limit and use these principles to design a number of new solar absorbers with the key feature of having an elevated LDOS within the absorbing region of the device, opening new avenues for solar cell design and cost reduction

    Light trapping beyond the 4n^2 limit in thin waveguides

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    We describe a method for determining the maximum absorption enhancement in thin film waveguides based on optical dispersion relations. For thin film structures that support one, well-confined guided mode, we find that the absorption enhancement can surpass the traditional limit of 4n^2 when the propagation constant is large and/or the modal group velocity is small compared to the bulk value. We use this relationship as a guide to predicting structures that can exceed the 4n^2 light trapping limit, such as plasmonic and slot waveguides. Finally, we calculate the overall absorption for both single and multimode waveguides, and show examples of absorption enhancements in excess of 4n^2 for both cases

    Simulations of solar cell absorption enhancement using resonant modes of a nanosphere array

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    We propose an approach for enhancing the absorption of thin-film amorphous silicon solar cells using periodic arrangements of resonant dielectric nanospheres deposited as a continuous film on top of a thin planar cell. We numerically demonstrate this enhancement using 3D full field finite difference time domain simulations and 3D finite element device physics simulations of a nanosphere array above a thin-film amorphous silicon solar cell structure featuring back reflector and anti-reflection coating. In addition, we use the full field finite difference time domain results as input to finite element device physics simulations to demonstrate that the enhanced absorption contributes to the current extracted from the device. We study the influence of a multi-sized array of spheres, compare spheres and domes and propose an analytical model based on the temporal coupled mode theory

    Community detection and role identification in directed networks: understanding the Twitter network of the care.data debate

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    With the rise of social media as an important channel for the debate and discussion of public affairs, online social networks such as Twitter have become important platforms for public information and engagement by policy makers. To communicate effectively through Twitter, policy makers need to understand how influence and interest propagate within its network of users. In this chapter we use graph-theoretic methods to analyse the Twitter debate surrounding NHS Englands controversial care.data scheme. Directionality is a crucial feature of the Twitter social graph - information flows from the followed to the followers - but is often ignored in social network analyses; our methods are based on the behaviour of dynamic processes on the network and can be applied naturally to directed networks. We uncover robust communities of users and show that these communities reflect how information flows through the Twitter network. We are also able to classify users by their differing roles in directing the flow of information through the network. Our methods and results will be useful to policy makers who would like to use Twitter effectively as a communication medium

    Silicon Solar Cell Light-Trapping Using Defect Mode Photonic Crystals

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    Nanostructured active or absorbing layers of solar cells, including photonic crystals and wire arrays, have been increasingly explored as potential options to enhance performance of thin film solar cells because of their unique ability to control light. We show that 2D photonic crystals can improve light trapping by an enhanced density of optical states and improved incoupling, and demonstrate, using FDTD simulation, absorption enhancements in 200nm thick crystalline silicon solar cells of up to 205% from λ = 300nm to 1100nm compared to a planar cell with an optimized two-layer antireflection coating. We report here a method to further enhance absorption by introducing a lattice of coupled defect modes into the photonic crystal, which modify the available optical states in the absorber. Our results show that 2D photonic crystals are a viable and rich research option for light trapping in thin film photovoltaics

    Predictive Factors of Literacy Achievement in Young Gifted Children in Rural Schools

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    The present study investigated predictive factors of literacy achievement in third-grade students identified as gifted in rural schools. The sample consisted of 180 identified students in a total of eight districts, three of which were randomly assigned to the treatment condition and five of which were randomly assigned to the control condition. Students in the treatment condition received instruction with a place-based folklore unit of the Challenge Leading to Engagement, Achievement, and Results (CLEAR) curriculum, a language arts based curriculum designed to challenge gifted learners, in addition to an intervention promoting an incremental mind-set. Results of the present study indicated that prior achievement, mind-set, and gender were all statistically and practically significant predictors of literacy achievement for students identified as gifted in rural areas. A stronger incremental mind-set was associated with lower literacy achievement scores. Practical implications and recommendations, as well as limitations and directions for further research, were discussed

    Solid state television camera system Patent

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    Solid state television camera system consisting of monolithic semiconductor mosaic sensor and molecular digital readout system
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