Search results for "Sensor"

A fully-automated procedure for measuring the electrical parameters of an induction motor drive with rotor at standstill

2003

The paper presents an automatic procedure to measure at standstill the electrical parameters of an induction motor fed by a PWM voltage source inverter. The proposed procedure executes automatically three tests using only the available PWM inverter control technique to obtain the required motor supply voltages. It allows the measurement of all the T-form circuit electrical parameters starting from the nameplate data as data-entry. It uses only a current sensor and no voltage sensor and process on line the collected data samples with a fast and easy to implement recursive least squares algorithm. Effectiveness of the automated procedure has been proved both by simulation and experimental tes…

Sensorless Control of Induction-Motor Drive Based on Robust Kalman Filter and Adaptive Speed Estimation

2014

This paper deals with robust estimation of rotor flux and speed for sensorless control of motion control systems with an induction motor. Instead of using sixth-order extended Kalman filters (EKFs), rotor flux is estimated by means of a fourth-order descriptor-type robust KF, which explicitly takes into account motor parameter uncertainties, whereas the speed is estimated using a recursive least squares algorithm starting from the knowledge of the rotor flux itself. It is shown that the descriptor-type structure allows for a direct translation of parameter uncertainties into variations of the coefficients appearing in the model, and this improves the degree of robustness of the estimates. E…

Reduction of rating scale data by means of signal detection theory

1979

A d’-index computed from ratings of psychological stimuli does not necessarily represent the unbiased psychological distance between these stimuli. Such ratings may not be considered as discrimination tasks in the signal detection sense, because the rater has to discriminate between the psychological impact of the stimuli on some internal continuum rather than between the stimuli as such. The rater therefore can use stimulus-specific criteria for his decisions. As a result, the d’-index computed from the rating data will be biased.

2017

The present study is a first attempt to experimentally test the impact of two specific social factors, namely social conformity pressure and a sense of being watched, on participants' judgments of the artistic quality of aesthetic objects. We manipulated conformity pressure with a test form in which a photograph of each stimulus was presented together with unanimously low (downward pressure) or high quality ratings (upward pressure) of three would-be previous raters. Participants' sense of being watched was manipulated by testing each of them in two settings, one of which contained an eyespots stimulus. Both social factors significantly affected the participants' judgments-unexpectedly, how…

Assessment of Classifiers and Remote Sensing Features of Hyperspectral Imagery and Stereo-Photogrammetric Point Clouds for Recognition of Tree Specie…

2018

Recognition of tree species and geospatial information on tree species composition is essential for forest management. In this study, tree species recognition was examined using hyperspectral imagery from visible to near-infrared (VNIR) and short-wave infrared (SWIR) camera sensors in combination with a 3D photogrammetric canopy surface model based on RGB camera stereo-imagery. An arboretum with a diverse selection of 26 tree species from 14 genera was used as a test area. Aerial hyperspectral imagery and high spatial resolution photogrammetric color imagery were acquired from the test area using unmanned aerial vehicle (UAV) borne sensors. Hyperspectral imagery was processed to calibrated …

Genetic variants linked to myopic macular degeneration in persons with high myopia: CREAM Consortium.

2019

Purpose: To evaluate the roles of known myopia-associated genetic variants for development of myopic macular degeneration (MMD) in individuals with high myopia (HM), using case-control studies from the Consortium of Refractive Error and Myopia (CREAM). Methods: A candidate gene approach tested 50 myopia-associated loci for association with HM and MMD, using meta-analyses of case-control studies comprising subjects of European and Asian ancestry aged 30 to 80 years from 10 studies. Fifty loci with the strongest associations with myopia were chosen from a previous published GWAS study. Highly myopic (spherical equivalent [SE] ≤ -5.0 diopters [D]) cases with MMD (N = 348), and two sets of cont…

The effect of fractal contact lenses on peripheral refraction in myopic model eyes.

2014

Purpose: To test multizone contact lenses in model eyes: Fractal Contact Lenses (FCLs), designed to induce myopic peripheral refractive error (PRE). Methods: Zemax ray-tracing software was employed to simulate myopic and accommodation-dependent model eyes fitted with FCLs. PRE, defined in terms of mean sphere M and 90–180 astigmatism J180, was computed at different peripheral positions, ranging from 0 to 35 in steps of 5, and for different pupil diameters (PDs). Simulated visual performance and changes in the PRE were also analyzed for contact lens decentration and model eye accommodation. For comparison purposes, the same simulations were performed with another commercially available conta…

The stenopaeic slit: an analytical expression to quantify its optical effects in front of an astigmatic eye.

2001

The stenopaeic slit is a trial case accessory used in subjective refraction, especially when high astigmatism is present. In spite of its simplicity, the effect of the slit when it is not oriented along one of the principal meridians of the examined eye is difficult to predict, even in terms of classical geometrical optics. In this paper, the optical principles of the slit are considered with full details in the theoretical framework of the dioptric power space. An analytical expression to obtain the residual refractive error when a stenopaeic slit is placed in front of an astigmatic eye at any orientation is deduced. In the light of these results, some aspects of the clinical procedure are…

Contrast sensitivity after refractive lens exchange with diffractive multifocal intraocular lens implantation in hyperopic eyes

2008

Contrast Test chart at distance and near under 3 luminance levels (85.0 cd/m 2 , 5.0 cd/m 2 , and 2.5 cd/m 2 ) before and after RLE with bilateral AcrySof ReSTOR IOL implantation in 30 hyperopic eyes with presbyopia and low astigmatism (%1.0 diopter). Results after surgery were compared with those before surgery. RESULTS: Six months postoperatively, the mean residual spherical equivalent refractive error was 0.21 diopter G 0.19 (SD). The best corrected distance and near visual acuities were comparable to those before surgery. For distance vision, the safety index was 1.02 and the efficacy index was 0.91. For near vision, the values were 1.04 and 1.02, respectively. There were no statistical…

Android lietotne ceļu locītavu rehabilitācijai

2016

Kvalifikācijas darbā ir izstrādāta Android lietotne ceļa locītavu rehabilitācijai. Tā sastāv no divām daļām, kas katra paredzēta savai lietotāju grupai. Pirmā daļa ir paredzēta pacientam, kurš veic rehabilitācijas procesu. Tā komunicē ar iegulto ierīci, kas tiek stiprināta pie pacienta locītavas un ar sensoru palīdzību raida informāciju uz Android ierīci. Tā nodrošina iespēja sekot līdzi vingrinājumu pildīšanas kvalitātei reāllaikā, papildus sūtot datus ārstam. Savukārt otrā daļa ir paredzēta ārstam. Tajā būs iespēja sekot līdzi savu pacientu veselības stāvoklim atveseļošanās laikā, ērti un uzskatāmi pārraugot rehabilitācijas procesu. Izstrādāto lietotņu sistēmas mērķis ir atvieglot rehabil…