Search results for "Correlation"
showing 10 items of 2282 documents
On the statistical properties of the capacity of amplify-and-forward channels under LOS conditions
2008
Amplify-and-forward channels in cooperative networks provide a promising improvement in the network coverage and system throughput. Under line-of-sight (LOS) propagation conditions in such cooperative networks, the overall fading channel can be modeled by a double Rice process. In this article, we have studied the statistical properties of the capacity of double Rice fading channels. We have derived the analytical expressions for the probability density function (PDF), cumulative distribution function (CDF), level-crossing rate (LCR), and average duration of fades (ADF) of the channel capacity. The obtained results are studied for different values of the amplitudes of the LOS components in …
Optical implementation of the weighted sliced orthogonal nonlinear generalized correlation for nonuniform illumination conditions.
2002
Optical pattern recognition under variations of illumination is an important issue. The sliced orthogonal nonlinear generalized (SONG) correlation has been proposed as an optical pattern recognition tool to discriminate with high efficiency between objects. But, at the same time, the SONG correlation is very sensitive to gray-scale image variations. In a previous work, we expanded the definition of the SONG correlation to the Weighted SONG (WSONG) correlation to modify the discrimination capability in a controlled way. Here, we propose to use the WSONG when pattern recognition is obtained by means of optical correlation under nonuniform illumination. The calculation of the WSONG correlation…
Assessment of image quality of intracoronary ultrasound systems with tissue-equivalent vessel phantoms
2002
Imaging of vascular structures by intracoronary ultrasound (ICUS) is finding more and more applications in coronary diagnosis and in the assessment of interventional access. The authors describe a method for easy and quick production of tissue-equivalent vessel phantoms from a special hydrocolloid. The mechanical tolerance is less than 3/100 mm. With these phantoms the authors tested the calibration and measured the resolution properties of the SONOS intravascular ultrasonic system (Hewlett Packard). The measurements revealed a slight space related underestimation of diameters up to 280 /spl mu/m. Using cross correlation and auto correlation functions the authors analyzed digitized ultrason…
Multi-speckle autocorrelation spectroscopy — a new strategy to monitor ultraslow dynamics in dense and nonergodic media
2007
We present a modification of the conventional dynamic light scattering set-up which allows to monitor the intensity fluctuations of many independent spatial Fourier components of the density fluctuations, i.e. “speckles”, simultaneously by using a charge-coupled device (CCD) camera as area detector. By averaging over the intensity autocorrelation function the final 10–20% decay of the intermediate scattering function in very dense colloidal dispersions is obtained with much higher accuracy. At the same time this multi-speckle autocorrelation spectroscopy provides an alternative route for constructing ensemble-averaged intermediate scattering functions in nonergodic media by replacing the av…
Coupled retrieval of aerosol optical thickness, columnar water vapor and surface reflectance maps from ENVISAT/MERIS data over land
2008
An algorithm for the derivation of atmospheric parameters and surface reflectance data from MEdium Resolution Imaging Specrometer Instrument (MERIS) on board ENVIronmental SATellite (ENVISAT) images has been developed. Geo-rectified aerosol optical thickness (AOT), columnar water vapor (CWV) and spectral surface reflectance maps are generated from MERIS Level-1b data over land. The algorithm has been implemented so that AOT, CWV and reflectance products are provided on an operational manner, making no use of ancillary parameters apart from those attached to MERIS products. For this reason, it has been named Self-Contained Atmospheric Parameters Estimation from MERIS data (SCAPE-M). The fund…
Multispectral colour analysis for quantitative evaluation of pseudoisochromatic color deficiency tests
2010
Multispectral color analysis was used for spectral scanning of Ishihara and Rabkin color deficiency test book images. It was done using tunable liquid-crystal LC filters built in the Nuance II analyzer. Multispectral analysis keeps both, information on spatial content of tests and on spectral content. Images were taken in the range of 420-720nm with a 10nm step. We calculated retina neural activity charts taking into account cone sensitivity functions, and processed charts in order to find the visibility of latent symbols in color deficiency plates using cross-correlation technique. In such way the quantitative measure is found for each of diagnostics plate for three different color deficie…
Dynamic aphasia and the generation of language
2004
Severely reduced propositional speech in the context of intact nominal language skills (i.e., repetition, naming, comprehension, and reading) is the hallmark of dynamic aphasia (Luria, 1970). Recent evidence suggests there may be different types of dynamic aphasia as some patients do not produce any response on verbal generation tasks, whilst others are able to perform normally on verbal genera- tion tasks. For example, Robinson and colleagues (Robinson, Blair, & Cipolotti, 1998; Robinson, Shallice, & Cipolotti, 2004) reported two dynamic aphasics who failed to produce a verbal response when many verbal response options were activated by a stimulus, but not when a dominant response was avai…
Correlations of the distribution of spin states in spin crossover compounds
1999
Abstract Short range correlations of the distribution of high spin (HS) and low spin (LS) states show up in thermal spin transition curves, decay curves of the light induced metastable HS state (LIESST state), and in structural features during the spin transitions. Correlations are due to short range interactions between the spin crossover molecules. Short range interactions may compete with omnipresent long range interactions and give rise to interesting spin transition phenomena. In this paper, the effect of correlations on the thermal spin transition in the mixed crystal system [Fe x Zn 1− x (pic) 3 ]Cl 2 ·EtOH (pic=picolylamine) is discussed. In particular the step in the thermal transi…
Comparison of magnetic resonance imaging of inhaled SF6 with respiratory gas analysis
2008
Magnetic resonance imaging of inhaled fluorinated inert gases ((19)F-MRI) such as sulfur hexafluoride (SF(6)) allows for analysis of ventilated air spaces. In this study, the possibility of using this technique to image lung function was assessed. For this, (19)F-MRI of inhaled SF(6) was compared with respiratory gas analysis, which is a global but reliable measure of alveolar gas fraction. Five anesthetized pigs underwent multiple-breath wash-in procedures with a gas mixture of 70% SF(6) and 30% oxygen. Two-dimensional (19)F-MRI and end-expiratory gas fraction analysis were performed after 4 to 24 inhaled breaths. Signal intensity of (19)F-MRI and end-expiratory SF(6) fraction were evaluat…
Predictores cognitivos de la intención de práctica y la percepción de las relaciones en el deporte: análisis de la pasión como mediadora (Cognitive p…
2019
Este estudio analizó el papel de la inteligencia en el juego y la motivación como predictores de la intención de práctica deportiva y las relaciones sociales. Asimismo examina el papel de la motivación autodeterminada y la pasión (armoniosa y obsesiva) como mediadoras de esta relación, incorporando la percepción de conflicto. Participaron 180 jugadores adolescentes de fútbol, baloncesto y balonmano, de ambos géneros (124 chicos y 56 chicas) y de edades comprendidas entre 15 y 19 años (M= 15,9; S= 1,029). Se llevó a cabo un análisis correlacional y análisis SEM (Structural Equation Modeling) de dos modelos estructurales, uno con la pasión armoniosa y otro con la pasión obsesiva. El ajuste de…