31,034 research outputs found

    Flap-lag-torsion aeroelastic stability of a circulation control rotor in forward flight

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    The aeroelastic stability of a circulation control rotor blade undergoing three degrees of motion (flap, lag, and torsion) is investigated in forward flight. Quasi-steady strip theory is used to evaluate the aerodynamics forces; and the airfoil characteristics are from data tables. The propulsive and the auxiliary power trims are calculated from vehicle and rotor equilibrium equations through the numerical integration of element forces in azimuth as well as in radial directions. The nonlinear time dependent periodic blade response is calculated using an iterative procedure based on Floquet theory. The periodic perturbation equations are solved for stability using Floquet transition matrix theory. The effects of several parameters on blade stability are examined, including advance ratio, collective pitch, thrust level, shaft tilt, structural stiffnesses variation, and propulsive and auxiliary power trims

    A Note on Testing ¡°Tax-and-Spend, Spend-and-Tax or Fiscal Synchronization¡±: The Case of China

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    The hypothesis of tax-and-spend, spend-and-tax, or fiscal synchronization was tested using annual time series data for China over the period 1977 to 1999. We include GDP as a control variable into the model like Baghestani and Mcnown (1994), Koren and Stiassny (1998), and Chang et al. (2002). The results from Granger causality test based on the corresponding multivariate error-correction models (MVECM) suggest feedback between government revenues and government expenditures, supporting the fiscal synchronization hypothesis for China.

    Exchange Rate Determination from Monetary Fundamentals: an Aggregation Theoretic Approach

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    We incorporate aggregation and index number theory into monetary models of exchange rate determination in a manner that is internally consistent with money market equilibrium. Divisia monetary aggregates and user-cost concepts are used for money supply and opportunity-cost variables in the monetary models. We estimate a flexible price monetary model, a sticky price monetary model, and the Hooper and Morton (1982) model for the US dollar/UK pound exchange rate. We compare forecast results using mean square error, direction of change, and Diebold-Mariano statistics. We find that models with Divisia indexes are better than the random walk assumption in explaining the exchange rate fluctuations. Our results are consistent with the relevant theory and the 'Barnett critique.'Exchange rate, forecasts, vector error correction, aggregation theory, index number theory, Divisia index number

    URNet : User-Resizable Residual Networks with Conditional Gating Module

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    Convolutional Neural Networks are widely used to process spatial scenes, but their computational cost is fixed and depends on the structure of the network used. There are methods to reduce the cost by compressing networks or varying its computational path dynamically according to the input image. However, since a user can not control the size of the learned model, it is difficult to respond dynamically if the amount of service requests suddenly increases. We propose User-Resizable Residual Networks (URNet), which allows users to adjust the scale of the network as needed during evaluation. URNet includes Conditional Gating Module (CGM) that determines the use of each residual block according to the input image and the desired scale. CGM is trained in a supervised manner using the newly proposed scale loss and its corresponding training methods. URNet can control the amount of computation according to user's demand without degrading the accuracy significantly. It can also be used as a general compression method by fixing the scale size during training. In the experiments on ImageNet, URNet based on ResNet-101 maintains the accuracy of the baseline even when resizing it to approximately 80% of the original network, and demonstrates only about 1% accuracy degradation when using about 65% of the computation.Comment: 12 page
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