The Experts below are selected from a list of 54 Experts worldwide ranked by ideXlab platform
Madhusudan Raghavan - One of the best experts on this subject based on the ideXlab platform.
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Analytical and Experimental Assessment of Some Novel Variable-Valve-Actuation Mechanisms
Journal of Mechanisms and Robotics, 2010Co-Authors: Burak A. Gecim, Madhusudan RaghavanAbstract:We describe our analytical and experimental works on three novel Variable valve actuation systems. These include a mechanical Variable-lift and duration concept, a hydraulic-lost-Motion Variable-lift system, and a valve-deactivation mechanism with unique features. These devices differ in their complexity and versatility but offer a spectrum of design solutions applicable to a range of products. The strengths and weaknesses of these different approaches are discussed and analyzed, and some test results are presented.
Burak A. Gecim - One of the best experts on this subject based on the ideXlab platform.
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Analytical and Experimental Assessment of Some Novel Variable-Valve-Actuation Mechanisms
Journal of Mechanisms and Robotics, 2010Co-Authors: Burak A. Gecim, Madhusudan RaghavanAbstract:We describe our analytical and experimental works on three novel Variable valve actuation systems. These include a mechanical Variable-lift and duration concept, a hydraulic-lost-Motion Variable-lift system, and a valve-deactivation mechanism with unique features. These devices differ in their complexity and versatility but offer a spectrum of design solutions applicable to a range of products. The strengths and weaknesses of these different approaches are discussed and analyzed, and some test results are presented.
Sun Hong - One of the best experts on this subject based on the ideXlab platform.
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Prism Material Dispersion Effects on the Total Dispersion of Prism Pair System
1997Co-Authors: Sun HongAbstract:The contribution of prism material dispersion to amount of prism pairs system dispersion is discussed. It is found that the second and third order dispersion depend on the distance between two prisms (l) and Motion Variable(Δ). As the optical path inside prism increases, the positive dispersion increases and the negative dispersion decreases for the prism pair.
Etienne Mémin - One of the best experts on this subject based on the ideXlab platform.
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Bayesian inference of models and hyper-parameters for robust optic-flow estimation
IEEE Transactions on Image Processing, 2012Co-Authors: Patrick Héas, Cédric Herzet, Etienne MéminAbstract:Selecting optimal models and hyper-parameters is crucial for accurate optic-flow estimation. This paper provides a solution to the problem in a generic Bayesian framework. The method is based on a conditional model linking the image intensity function, the unknown velocity field, hyper-parameters and the prior and likelihood Motion models. Inference is performed on each of the three-level of this so-defined hierarchical model by maximization of marginalized \textit{a posteriori} probability distribution functions. In particular, the first level is used to achieve Motion estimation in a classical a posteriori scheme. By marginalizing out the Motion Variable, the second level enables to infer regularization coefficients and hyper-parameters of non-Gaussian M-estimators commonly used in robust statistics. The last level of the hierarchy is used for selection of the likelihood and prior Motion models conditioned to the image data. The method is evaluated on image sequences of fluid flows and from the ''Middlebury" database. Experiments prove that applying the proposed inference strategy yields better results than manually tuning smoothing parameters or discontinuity preserving cost functions of the state-of-the-art methods.
Soo Jeon - One of the best experts on this subject based on the ideXlab platform.
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CDC - Self recovery phenomenon of mechanical systems with an unactuated cyclic Variable
2012 IEEE 51st IEEE Conference on Decision and Control (CDC), 2012Co-Authors: Dong Eui Chang, Soo JeonAbstract:Conservation laws in nature correspond to symmetries of related physical systems (Noether's theorem). Conservation of momentum, for instance, can be interpreted by the symmetric property of a certain Motion Variable known as the cyclic Variable. If a symmetry-breaking force such as a dissipative force or the gravitational force, is applied to the cyclic Variable, then the momentum is not conserved any longer in general. The main objective of this paper is to show that there exists a particular type of viscous damping-like force that breaks the symmetry but induces a new conserved quantity in place of the original momentum map. This new conserved quantity can be constructed by combining the time integral of a force linear in velocity and the original momentum map associated with the symmetry. In terms of stability theory of dynamical systems, it can be shown that the existence of the new conserved quantity implies that the corresponding Motion Variable possesses, as we define in this paper, the self recovery phenomenon. More specifically, the corresponding Motion Variable will be globally attractive to the initial condition of the Variable.We discover that what is fundamental in this self recovery phenomenon is not the positivity of the coefficient of the force linear in the velocity, but certain properties of the time integral of the coefficient function, which can encompass a wide range of viscous damping forces. The self recovery effect and theoretical discoveries are demonstrated by simulation results using two examples: Elroy's beanie, and the torque-controlled inverted pendulum on a passive cart. The results in this paper will be useful in designing and controlling mechanical systems with underactuation.