Search results for "Filters"
showing 10 items of 92 documents
Sintonika un presbiopija
2017
Pēdējos gados sintonika kā metode ir kļuvusi pieejamāka un pielietojamāka redzes uztveres optometristu vidū. Metodi pielieto, lai sabalansētu simpātisko un parasimpātisko nervu sistēmu saskaņotu darbību, pielietojot dažādu krāsu filtrus. Darba mērķis bija novērtēt sintonikā pielietoto filtru iespējas sākotnējas presbiopijas ārstēšanai. Darbā tiek analizēti pacientu dati par sintonikas iedarbības efektivitāti sākotnējās presbiopijas gadījumos. Redzes asums, bet novērtējot to bez tuvuma aditīva, akomodācijas amplitūda un zīlītes α-ω mērījumi uzrāda statistiski nozīmīgi atšķirīgus rezultātus pirms un pēc sintonikas pielietošanas. Ietekme ir arī uz formas redzes funkcionālo lauku, kā arī uz fun…
Iterative altitude-aiding algorithm for improved GNSS positioning
2011
The system proposed in this study relies on a WAVE P2P network, which is a proper standard to fit the vehicular environment wireless communications requests. Starting from the chance to exchange information given by this infrastructure, the possibility to improve the performance of a global navigation satellite system (GNSS) receiver based on a Kalman filter is considered. This improvement is obtained exploiting the external altitude measurements provided by other peers in the network, equipped with GNSS receivers. The topic of an altitude-aided system has been described in a previous work, that highlighted the need for a parameter that points out the effectiveness and the consistency of th…
Clustering techniques for personal photo album management
2009
In this work we propose a novel approach for the automatic representation of pictures achieving at more effective organization of personal photo albums. Images are analyzed and described in multiple representation spaces, namely, faces, background and time of capture. Faces are automatically detected, rectified and represented projecting the face itself in a common low-dimensional eigenspace. Backgrounds are represented with low-level visual features based on RGB histogram and Gabor filter bank. Faces, time and background information of each image in the collection is automatically organized using a mean-shift clustering technique. Given the particular domain of personal photo libraries, wh…
Dead-time impact on the harmonic distortion and conversion efficiency in a three-phase five-level Cascaded H-Bridge inverter: mathematical formulatio…
2023
To avoid leg short-circuit in inverters, dead time must be introduced on leg gate signals. Dead time affects the inverter output voltage fundamental harmonic amplitude, voltage harmonic distortion and inverter efficiency by introducing additional voltage drops. In this regard, dead time effects have been widely investigated for traditional two-level three-phase voltage source inverters in the literature but not extensively for multilevel topology structures. This paper provides a detailed analysis of dead time impact on the harmonic distortion and efficiency of Cascaded H-Bridges Multilevel Inverters (CHBMIs). For this purpose, a general mathematical formulation to determine voltage drop du…
Depth Enhancement by Fusion for Passive and Active Sensing
2012
This paper presents a general refinement procedure that enhances any given depth map obtained by passive or active sensing. Given a depth map, either estimated by triangulation methods or directly provided by the sensing system, and its corresponding 2-D image, we correct the depth values by separately treating regions with undesired effects such as empty holes, texture copying or edge blurring due to homogeneous regions, occlusions, and shadowing. In this work, we use recent depth enhancement filters intended for Time-of-Flight cameras, and adapt them to alternative depth sensing modalities, both active using an RGB-D camera and passive using a dense stereo camera. To that end, we propose …
Acs aberāciju un gaismas izkliedes ietekme uz redzes kvalitāti.
2020
Darbs ir uzrakstīts angļu valodā 66 lapām. Tā satur 33 attēlus, 3 tabulas, 8 grafiki un 121 atsauces uz literatūras avotiem. Mērķis. Izpētīt saistību starp cilvēka redzi un acs iekšējo gaismas izkliedi un mēģināt saprast, vai intraokulārā gaismas izkliede ietekmē acs aberācijas. Izpētīta Strehl koeficientu normalitāte. Metodes. Redzes asumu un jutīgumu pret kontrastu novērtē parastā stāvoklī un ar 3 dažādiem izkliedes filtriem 10 jaunu un veselīgu acu grupai. Pašizveidota modeļa acs viļņu frontes kļūdas tiek izmeklētas ar izkliedes filtriem un bez tiem. Rezultāti. Redzes asums un jutība pret kontrastu ir sliktāka, ja izkliedēšanas filtri tiek novietoti subjekta acu priekšā (p <.05). VA iete…
KALMAN FILTERS FOR GNSS APPLICATIONS
2011
Advanced Analysis of Propagation Losses in Rectangular Waveguide Structures Using Perturbation of Boundary Conditions
2011
In this paper, propagation losses effects present in rectangular waveguide structures are rigorously considered. For this purpose, a new formulation based on the perturbation of the boundary conditions on the metallic walls of the waveguides combined with an Integral-Equation (IE) analysis technique is proposed. Following this advanced technique, the drawbacks of the classical power-loss method are overcome and a complex modal propagation constant is computed. To validate this theory, we have successfully compared our results with numerical data of lossy hollow waveguides. Next, a Computed-Aided-Design (CAD) software package based on such a novel modal analysis tool has been used to predict…
Pulmonary embolism: risk assessment and management.
2012
Acute pulmonary embolism (PE) poses a significant burden on health and survival. Its severity ranges from asymptomatic, incidentally discovered subsegmental thrombi to massive, pressor-dependent PE complicated by cardiogenic shock and multisystem organ failure. Rapid and accurate risk stratification is therefore of paramount importance to ensure the highest quality of care. This article critically reviews currently available and emerging tools for risk-stratifying acute PE, and particularly for distinguishing between elevated (intermediate) and low risk among normotensive patients. We focus on the potential value of risk assessment strategies for optimizing severity-adjusted management. Apa…
Effect of sport-tinted contact lenses for contrast enhancement on retinal straylight measurements
2008
PURPOSE: To investigate the effect of two tinted contact lenses (CL) designed for outdoor sports activity on the psychometric determination of retinal straylight using the compensation comparison method. METHODS: Thirteen emmetropic subjects were randomly fitted with two different tinted Nike Maxsight (Bausch & Lomb, Rochester, NY, USA) CL in one eye, while the contralateral eye was fitted with a clear lens made of the same material (Optima 38, Bausch & Lomb). Three valid straylight measurements were taken on each eye before and a few minutes after lens insertion, when lens stabilization had occurred. RESULTS: The subjects' mean straylight values were 0.90 +/- 0.09 at baseline and 0.95 +/- …