Search results for "Computer Vision and Pattern Recognition"
showing 10 items of 997 documents
Static output-feedback controller design for vehicle suspensions: an effective two-step computational approach
2014
In this study, a novel two-step methodology is applied in designing static output-feedback controllers for a class of vehicle suspension systems. Following this approach, an effective synthesis of static output-feedback controllers can be carried out by solving two consecutive linear matrix inequality optimisation problems. To illustrate the main features of the proposed design strategy, two different static output-feedback H 8 controllers are designed for a quarter-car suspension system. The first of those controllers uses the suspension deflection and the sprung mass velocity as feedback information, whereas the second one only requires the sprung mass velocity to compute the control acti…
A Note about Eigenvalues, SVD and PCA
2013
Notes on eigen-decomposition, PCA, SVD and connexions.
Combining Mendonça-Cipolla self-calibration and scene constraints
2011
International audience; In this paper, we propose a method that combines plane parallelism and the Mendonça/Cipolla self-calibration constraints. In our method each pair of images is treated independently and can therefore use a different pair of parallel planes not necessarily visible in the other views. While, for each pair of images, constraints on the singular values of the essential matrix provide two algebraic constraints on the intrinsic parameters, those we derive from plane parallelism have the advantage of providing two additional ones making the calibration of a no-skew camera possible from two images only.
Hereditariness of Aortic Tissue: In-Vitro Time-Dependent Failure of Human and Porcine Specimens
2018
This study aims to investigate the time dependent failure of aortic tissues for pathological and healthy samples by biomechanical testing. The experimental campaign has involved human pathological tissue and healthy swine tissue as preliminary study towards the development of novel failure criteria.
Hyperspectral terahertz microscopy via nonlinear ghost imaging
2020
Ghost imaging, based on single-pixel detection and multiple pattern illumination, is a crucial investigative tool in difficult-to-access wavelength regions. In the terahertz domain, where high-resolution imagers are mostly unavailable, ghost imaging is an optimal approach to embed the temporal dimension, creating a “hyperspectral” imager. In this framework, high resolution is mostly out of reach. Hence, it is particularly critical to developing practical approaches for microscopy. Here we experimentally demonstrate time-resolved nonlinear ghost imaging, a technique based on near-field, optical-to-terahertz nonlinear conversion and detection of illumination patterns. We show how space–time c…
Cost-Effective Treatment of Scalar Relativistic Effects for Multireference Systems: A CASSCF Implementation Based on the Spin-free Dirac-Coulomb Hami…
2016
We present an implementation of the complete active space-self-consistent field (CASSCF) method specifically designed to be used in four-component scalar relativistic calculations based on the spin-free Dirac-Coulomb (SFDC) Hamiltonian. Our implementation takes full advantage of the properties of the SFDC Hamiltonian that allow us to use real algebra and to exploit point-group and spin symmetry to their full extent while including in a rigorous way scalar relativistic effects in the treatment. The SFDC-CASSCF treatment is more expensive than its non-relativistic counterpart only in the orbital optimization step, while exhibiting the same computational cost for the rate-determining full conf…
Ambiguity function analysis of pulse train propagation: applications to temporal Lau filtering
2007
We use the periodic-signal ambiguity function for visualizing the intensity-spectrum evolution through propagation in a first-order dispersive medium. We show that the degree of temporal coherence of the optical source plays the role of a low-pass filter on the signal's ambiguity function. Based on this, we present a condition on the temporal Lau effect for filtering harmonics at fractions of the Talbot length. This result allows one to increase the repetition rate of a pulse train obtained from a sinusoidally phase-modulated CW signal.
Incoherent frequency-to-time mapping: application to incoherent pulse shaping
2007
After temporal amplitude modulation of a spectrally incoherent optical source the averaged intensity profile at the so-called temporal far-zone regime coalesces with a magnified replica of the spectral density function of the source. This has provided the basis for the generalization of the frequency-to-time mapping technique in the partially coherent case. Based on this fact, temporal intensity waveform generation is demonstrated by spectral filtering the incoherent source before the temporal modulation stage. We refer to this technique as full incoherent pulse shaping. Although only the average intensity of the output signal is properly shaped, intensity fluctuations between the different…
Angular shift of an electromagnetic beam reflected by a planar dielectric interface
1989
A mathematical procedure for obtaining theoretically an expression for the fields of a beam reflected by a planar interface separating two lossless, linear, isotropic, homogeneous media is presented. Comparison of this expression with that obtained when the beam undergoes reflection from a perfect conductor leads to the expression for the angular shift of the beam reflected by a planar dielectric interface. The cases of normal and parallel polarization of a microwave beam are considered. In the last case, a complete study for angles of incidence far and near the Brewster angle is made.
Spectral anomalies in focused waves of different Fresnel numbers
2004
Light propagation induces remarkable changes in the spectrum of focused diffracted beams. We show that spectral changes take place in the vicinity of phase singularities in the focal region of spatially coherent, polychromatic spherical waves of different Fresnel numbers. Instead of the Debye formulation, we use the Kirchhoff integral to evaluate the focal field accurately. We find that as a result of a decrease in the Fresnel number, some cylindrical spectral switches are geometrically transformed into conical spectral switches.