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  • NRN147 - Stage-dependent DSP Operation Range Clipping-induced Bit Resolution Reductions of Full Parallel 64-point FFTs Incorporated in FPGA-based Optical OFDM Receivers

    IEEE Xplore

    • Sensors and Devices, 
    • Modelling

    The fast Fourier transform (FFT) is the fundamental algorithm at the heart of an optical OFDM (OOFDM) transceiver. The high digital signal processing (DSP) complexity has become one of the most significant obstacles to experimentally demonstrating real-time high-capacity OOFDM transceivers. In this paper, stage-dependent clipping of FFT DSP operation dynamic range is proposed and extensively explored, for the first time, based on which an improved stage-dependent minimum bit resolution map is numerically identified by taking into account the DSP operation dynamic range-clipping and precision of FFT DSP operations.

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  • NRN119 - A constrained optimization solution for Caughey damping coefficients in seismic analysis,

    Engineering Computations

    • Modelling

    Extended from the classic Rayleigh damping model in structural dynamics, the Caughey damping model allows the damping ratios to be specified in multiple modes while satisfying the orthogonality conditions. Despite these desirable properties, Caughey damping suffers from a few major drawbacks: depending on the frequency distribution of the significant modes, it can be difficult to choose the reference frequencies that ensure reasonable values for all damping ratios corresponding to the significant modes; it cannot ensure all damping ratios are positive. This paper aims to present a constrained quadratic programming approach to address these issues.

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  • NRN026 From Dark to Bright: First-Order Perturbation Theory with Analytical Mode Normalization for Plasmonic Nanoantenna Arrays Applied to Refractive Index Sensing

    Physical Review Letters

    • Sensors and Devices, 
    • Modelling

    We present a first-order perturbation theory to calculate the frequency shift and linewidth change of photonic resonances in one- and two-dimensional periodic structures under modifications of the surrounding refractive index.

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  • NRN140 - An Alternative Route to Pentavalent Postperovskite

    Inorganic Chemistry

    • Materials

    The second-known pentavalent oxide postperovskite has been synthesized and its formation studied using in situ synchrotron data. The synthesis of postperovskite NaOsO3, from a KSbO3-like assemblage, occurs without any perovskite intermediate at almost one-third of the pressure required by the direct perovskite route. This work indicates that postperovskites can be more common, even occurring in systems where no perovskite is yet known, and could be more efficiently obtained if prior perovskite synthesis is avoided.

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  • NRN142 - Analytical solution for the lubrification force between 2 spheres in the bi-viscous fluid

    Physics of Fluids

    • Modelling

    An analytical solution for the calculation of the normal lubrication force acting between two moving spheres embedded in a shear-thinning fluid represented by a bi-viscous model is provided. The resulting force between the suspended spheres exhibits a consistent transition between the Newtonian constant-viscosity limits and it reduces to the well-known standard Newtonian lubrication theory for viscosity-ratio approaching one.

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