261 research outputs found

    Study of Sanmenxia Dam Effects on Backwater and Human Activities in Middle Yellow River, China

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    The study aimed to investigate Sanmenxia Dam effects on backwater and human activities in middle Yellow River through proposed models combined with statistical model, Backward Propagation Artificial Neural Network (BP-ANN) model, and hydrodynamic model

    On a metric view of the polynomial shift locus

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    We relate generic points in the shift locus SD\mathcal{S}_D of degree D2D\ge 2 polynomials to metric graphs. Using thermodynamic metrics on the space of metric graphs, we obtain a distance function ρD\rho_D on SD\mathcal{S}_D. We study the (in)completeness of the metric space (SD,ρD)(\mathcal{S}_D, \rho_D). We prove that when D3D \ge 3, the space (SD,ρD)(\mathcal{S}_D, \rho_D) is incomplete and its metric completion contains a subset homeomorphic to the space PSTD\mathbb{P}\mathcal{ST}_D^* introduced by DeMarco and Pilgrim. This provides a new way to understand the space PSTD\mathbb{P}\mathcal{ST}_D^*.Comment: 26 page

    Plasmonic nano-resonator enhanced one-photon luminescence from single gold nanorods

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    Strong Stokes and anti-Stokes one-photon luminescence from single gold nanorods is measured in experiments. It is found that the intensity and polarization of the Stokes and anti-Stokes emissions are in strong correlation. Our experimental observation discovered a coherent process in light emission from single gold nanorods. We present a theoretical mode, based on the concept of cavity resonance, for consistently understanding both Stokes and anti-Stokes photoluminescence. Our theory is in good agreement of all our measurements.Comment: 14 pages, 7 figures, 2 table

    Model-based multiobjective evolutionary algorithm optimization for HCCI engines

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    Modern engines feature a considerable number of adjustable control parameters. With this increasing number of degrees of freedom (DoFs) for engines and the consequent considerable calibration effort required to optimize engine performance, traditional manual engine calibration or optimization methods are reaching their limits. An automated and efficient engine optimization approach is desired. In this paper, interdisciplinary research on a multiobjective evolutionary algorithm (MOEA)-based global optimization approach is developed for a homogeneous charge compression ignition (HCCI) engine. The performance of the HCCI engine optimizer is demonstrated by the cosimulation between an HCCI engine Simulink model and a Strength Pareto Evolutionary Algorithm 2 (SPEA2)-based multiobjective optimizer Java code. The HCCI engine model is developed by Simulink and validated with different engine speeds (1500-2250 r/min) and indicated mean effective pressures (IMEPs) (3-4.5 bar). The model can simulate the HCCI engine's indicated specific fuel consumption (ISFC) and indicated specific hydrocarbon (ISHC) emissions with good accuracy. The introduced MOEA optimization is an approach to efficiently optimize the engine ISFC and ISHC simultaneously by adjusting the settings of the engine's actuators automatically through the SPEA2. In this paper, the settings of the HCCI engine's actuators are intake valve opening (IVO) timing, exhaust valve closing (EVC) timing, and relative air-to-fuel ratio lambdalambda. The cosimulation study and experimental validation results show that the MOEA engine optimizer can find the optimal HCCI engine actuators' settings with satisfactory accuracy and a much lower time consumption than usual
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