Results 1 - 10 of 3,012

Flexible camera calibration by viewing a plane from unknown orientations

by Zhengyou Zhang , 1999
"... We propose a flexible new technique to easily calibrate a camera. It only requires the camera to observe a planar pattern shown at a few (at least two) different orientations. Either the camera or the planar pattern can be freely moved. The motion need not be known. Radial lens distortion is modeled ..."
Abstract - Cited by 511 (7 self) - Add to MetaCart
is modeled. The proposed procedure consists of a closed-form solution, followed by a nonlinear refinement based on the maximum likelihood criterion. Both computer simulation and real data have been used to test the proposed technique, and very good results have been obtained. Compared with classical

On the time course of perceptual choice: the leaky competing accumulator model

by Marius Usher, James L. McClelland - PSYCHOLOGICAL REVIEW , 2001
"... The time course of perceptual choice is discussed in a model based on gradual and stochastic accumulation of information in non-linear decision units with leakage (or decay of activation) and competition through lateral inhibition. In special cases, the model becomes equivalent to a classical diffus ..."
Abstract - Cited by 480 (19 self) - Add to MetaCart
The time course of perceptual choice is discussed in a model based on gradual and stochastic accumulation of information in non-linear decision units with leakage (or decay of activation) and competition through lateral inhibition. In special cases, the model becomes equivalent to a classical

A neural mass model for MEG/EEG: coupling and neuronal dynamics

by Olivier David, Karl J. Friston - NeuroImage , 2003
"... Although MEG/EEG signals are highly variable, systematic changes in distinct frequency bands are commonly encountered. These frequency-specific changes represent robust neural correlates of cognitive or perceptual processes (for example, alpha rhythms emerge on closing the eyes). However, their func ..."
Abstract - Cited by 81 (21 self) - Add to MetaCart
the frequency of oscillations. In this work we extended the classical nonlinear lumped-parameter model of alpha rhythms, initially developed by Lopes da Silva and colleagues [Kybernetik 15 (1974) 27], to generate more complex dynamics. We show that the whole spectrum of MEG/EEG signals can be reproduced within

Controllability of Lumped Parameter Chemical Reactors

by Rafael Maya-yescas , 2005
"... A methodology for the evaluation of control strategies and for the preliminary assessment of con-trollability of nonlinear control affine systems was proposed. Due to the fact that the full nonlinear model of the process is used, the methodology is applicable to any steady state that is chosen as th ..."
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and pairing of control and manipulate variables in lumped parameter chemical reactors, usu-ally Continuous Stirred Tank Reactors (CSTR), is not an easy task because of the lack of methodologies for a systematic evaluation of control schemes in nonlin-ear systems. Furthermore, intrinsic nonlinearities

ASSESSING UNCERTAINTY IN FUTURE PRESSURE CHANGES PREDICTED BY LUMPED-PARAMETER MODELS: A FIELD APPLICATION

by Omer Inanc Tureyen, Hulya Sarak, Mustafa Onur
"... Lumped parameter models provide an attractive alternative to numerical modeling of geothermal reservoirs with the distinct advantage of having to deal with fewer modeling parameters. Hence when such models are used, the aim of the modeling work is then to determine the parameters that best describe ..."
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, one can analyze various possible outcomes of the future predictions. In this work, we first introduce briefly two methods that can be used for predicting the uncertainty in future flow behavior predicted by lumped-parameter models; The Randomized Maximum Likelihood (RML) and the Ensemble Kalman Filter

Opinion dynamics and bounded confidence: Models, analysis and simulation

by Rainer Hegselmann, Ulrich Krause - Journal of Artificial Societies and Social Simulation , 2002
"... Abstract When does opinion formation within an interacting group lead to consensus, polarization or fragmentation? The article investigates various models for the dynamics of continuous opinions by analytical methods as well as by computer simulations. Section 2 develops within a unified framework t ..."
Abstract - Cited by 236 (4 self) - Add to MetaCart
the classical model of consensus formation, the variant of this model due to Friedkin and Johnsen, a time-dependent version and a nonlinear version with bounded confidence of the agents. Section 3 presents for all these models major analytical results. Section 4 gives an extensive exploration of the nonlinear

Particle Filters for Positioning, Navigation and Tracking

by Fredrik Gustafsson, Fredrik Gunnarsson, Niclas Bergman, Urban Forssell, Jonas Jansson, Rickard Karlsson, Per-Johan Nordlund , 2002
"... A framework for positioning, navigation and tracking problems using particle filters (sequential Monte Carlo methods) is developed. It consists of a class of motion models and a general non-linear measurement equation in position. A general algorithm is presented, which is parsimonious with the part ..."
Abstract - Cited by 219 (23 self) - Add to MetaCart
the advantage over classical Kalman filter based algorithms. Here the use of non-linear models and non-Gaussian noise is the main explanation for the improvement in accuracy. More specifically, we describe how the technique of map matching is used to match an aircraft's elevation profile to a digital

The Digital TV Filter and Nonlinear Denoising

by Tony F. Chan, Stanley Osher, Jianhong Shen - IEEE Trans. Image Process , 2001
"... Motivated by the classical TV (total variation) restoration model, we propose a new nonlinear filter---the digital TV filter for denoising and enhancing digital images, or more generally, data living on graphs. The digital TV filter is a data dependent lowpass filter, capable of denoising data witho ..."
Abstract - Cited by 154 (14 self) - Add to MetaCart
Motivated by the classical TV (total variation) restoration model, we propose a new nonlinear filter---the digital TV filter for denoising and enhancing digital images, or more generally, data living on graphs. The digital TV filter is a data dependent lowpass filter, capable of denoising data

Sensitivity analysis of nonlinear lumped parameter models of HIV infection dynamics

by D. M. Bortz, P. W. Nelson - Bull. Math. Biol , 2004
"... A formal sensitivity analysis is performed on a delay differential equation model for the viral dynamics of an in vivo HIV infection during protease inhibitor therapy. We present results of both a differential analysis as well as a principle component based analysis and provide evidence that suggest ..."
Abstract - Cited by 11 (2 self) - Add to MetaCart
A formal sensitivity analysis is performed on a delay differential equation model for the viral dynamics of an in vivo HIV infection during protease inhibitor therapy. We present results of both a differential analysis as well as a principle component based analysis and provide evidence

Estimation and identification of parameters in a lumped cerebrovascular model

by Scott R. Pope, Laura M. Ellwein, Cheryl L. Zapata, Vera Novak, C. T. Kelley, Mette S. Olufsen - Math Biosci Eng , 2009
"... (Communicated by James F. Selgrade) Abstract. This study shows how sensitivity analysis and subset selection can be employed in a cardiovascular model to estimate total systemic resistance, cerebrovascular resistance, arterial compliance, and time for peak systolic ventricular pressure for healthy y ..."
Abstract - Cited by 6 (3 self) - Add to MetaCart
young and elderly subjects. These quantities are parameters in a simple lumped parameter model that predicts pressure and flow in the systemic circulation. The model is combined with experimental measurements of blood flow velocity from the middle cerebral artery and arterial finger blood pressure
Results 1 - 10 of 3,012