Metallic components such as plasmonic gratings and plasmonic lenses are routinely used to convert free-space beams into propagating surface plasmon polaritons and vice versa. This generation of couplers handles relatively simple light beams, such as plane waves or Gaussian beams. Here we present a powerful generalization of this strategy to more complex wave-fronts, such as vortex beams that ca...

An initial startupmethod for a spacecraft actuated by a pyramidal arrangement of variable-speed controlmoment gyroscopes is developed. The method provides closed-loop internal momentum tracking control to enable the flywheels to start from rest and reach desired wheel speeds. The proposed controller functioning as a variable-speed control moment gyroscope steering law is developed in terms of t...

The present talks deals with a uniform approach to the discretization in time of rigid body dynamics, nonlinear structural mechanics and flexible multibody systems. In particular, it is shown that a uniform set of differential-algebraic equations (DAEs) with constant mass matrix governs the motion of rigid bodies and semi-discrete formulations of structural components (such as geometrically exa...

this study intended to develop a model describing speaking strategies for efl learners by taking into account the effects of learners’ gender and proficiency on the application of strategies. accordingly, this study was planned to have two main analyses, namely qualitative and quantitative. in this respect, 30 efl learners' viewpoints were sought, and then, based on the elicited responses, a 21...

The Covariance matrix adaptation evolution strategy (CMA-ES) evolves a multivariate Gaussian distribution for continuous optimization. The evolution path, which accumulates historical search direction in successive generations, plays a crucial role in the adaptation of covariance matrix. In this paper, we investigate what the evolution path approximates in the optimization procedure. We show th...

Relying on a comprehensive data set of news releases, we construct monthly firm-level news sentiment scores during the 2000–2014 period and document a news momentum phenomenon that stocks with more positive news in the past generate more positive news in the future. We propose two hypotheses to explain this phenomenon and find that news momentum is driven by the persistence of firms’ fundamenta...

In the framework of a reduced form asset pricing model featuring linear-in-z betas and risk premiums with lagged macro instruments, I propose a clean measure of mispricing that is free from the omitted-variable bias due to either missing priced factors or missing instruments. Applying the model to U.S. stock returns for 1927-2005, I find that momentum and contrarian strategies are related to th...

New equations governing the scale transformation behaviors of a QFT with underlying structures is derived and they are valid for all QFTs (with whatever renormalizability). These equations, with their several equivalent versions, can yield some new and significant insights and results that are difficult to see in the conventional renormalization programs. Among the several equivalent versions, ...

We explain excess volatility, short-term momentum and long-term reversal of asset prices by a repeated game version of Keynes’ beauty contest. In every period the players can either place a buy or sell order on the asset market. The actual price movement is determined by average market orders and noise. It is common knowledge that the noise process is an exogenous random walk. Our model explain...