Smear correction of highly-variable, frame-transfer-CCD images with application to polarimetry

Image smear, produced by the shutter-less operation of frame transfer CCD detectors, can be detrimental for many imaging applications. Existing algorithms used to numerically remove smear, do not contemplate cases where intensity levels change considerably between consecutive frame exposures. In this report we reformulate the smearing model to include specific variations of the sensor illumination. The corresponding desmearing expression and its noise properties are also presented and demonstrated in the context of fast imaging polarimetry.Comment: Article accepted for publication in Applied Optics on 08 Jun 201

Application of a Mamdani-type fuzzy rule-based system to segment periventricular cerebral veins in susceptibility-weighted images

This paper presents an algorithm designed to segment veins in the periventricular region of the brain in susceptibility-weighted magnetic resonance images. The proposed algorithm is based on a Mamdani-type fuzzy rule-based system that enables enhancement of veins within periventricular regions of interest as the first step. Segmentation is achieved after determining the cut-off value providing the best trade-off between sensitivity and specificity to establish the suitability of each pixel to belong to a cerebral vein. Performance of the algorithm in susceptibility-weighted images acquired in healthy volunteers showed very good segmentation, with a small number of false positives. The results were not affected by small changes in the size and location of the regions of interest. The algorithm also enabled detection of differences in the visibility of periventricular veins between healthy subjects and multiple sclerosis patients. © Springer International Publishing Switzerland 2016.Postprint (author's final draft

Development of a 1-D solver for a supersonic ejector

Els primers ejectors van ser inventats a prinicipi del segle XX, i molta recerca s'ha fet fins al dia d'avui. El departament de mecànica de fluids de la UPC ha desenvolupat un ejector supersònic i han fet recerca per obtenir la geometria més òptima. Els investigadors Roberto Castilla López i Llorenç Macià han desenvolupat també una simulació en CFD usant el programa OpenFOAM per poder analitzar les diferents geometries i analitzar el fluxe dintre de l'ejector. Han vist que es necessita un programa (solver) per solucionar el fluxe en el cas unidimensional i estacionari, per a que pugui interactuar amb el model ja creat que és més complexe i incorpora el fluxe transitori. El model unidimensional serà empleat per proporcionar d'una manera molt ràpida resultats aproximats utilitzant una geometria ja coneguda i uns coeficients de pèrduda que seràn proporcionats per el CFD per acabar d'ajustar el rendiment. Aquest fet permetrà estudiar d'una manera molt més ràpida si distintes geometries seràn candidates a aconseguir un millor rendiment. És necessari aquest programa unidimensional perquè el CFD és un procés molt més lent, i no permet provar una quantitat molt gran de geometries diferents, fet que provoca que no és pugui dur a terme un procés d'optimització de la geometria. Per tant, s'ha desenvolupat un programa unidimensional utilitzant el llenguatge Python. El model és capaç de calcular el rendiment de un ejector donada la seva geometria i és capaç de predir la quantitat de vuit aconseguida de una manera molt aproximada.Los primeros eyectores fueron inventados a principios del siglo XX, y desde entonces mucha investigación se ha realizado. El departamento de mecánica de fluidos de la UPC ha desarrollado un eyector supersónico y han llevado a cabo estudios con el objetivo de conseguir la geometria más óptima. Los investigadores Roberto Castilla López y Lorenzo Macià también han desarrollado una simulación en CFD usando el programa OpenFOAM para poder analizar diferentes geometrías y analizar el flujo dentro del eyector. Han visto que se necesita un programa (solver) para solucionar el flujo en el caso unidimensional y estacionario, y que pueda interactuar con el modelo de CFD ya creado que es más complejo e incorpora el flujo transitorio. El modelo unidimensional será utilizado para proporcionar de una manera muy rápida resultados aproximados utilizando una geometría ya conocida y unos coeficientes de pérdida que serán proporcionados por el CFD para acabar de ajustar el rendimiento. Desarrollar este programa unidimensional permitirá estudiar de una manera mucho más rápida distintas geometrías y seleccionar cuáles serán candidatas a conseguir un mejor rendimiento. Es necesario este programa unidimensional para interactuar con el CFD, que es un proceso mucho más lento y que no permite probar una cantidad muy grande de geometrías diferentes. Estos últimos inconvenientes provocan que no se pueda llevar a cabo un proceso de optimización de la geometría únicamente con el CFD. Por lo tanto, se ha desarrollado un programa unidimensional utilizando el lenguaje Python. El modelo es capaz de calcular el rendimiento de un eyector dada su geometría y es capaz de predecir la cantidad de vacío conseguida de una manera muy aproximada.The first ejectors were invented in the 1900s, and a lot of research has been done since that time. The fluid mechanics department of the UPC has been searching for an optimal geometry in order to implement it to a supersonic ejector. Researchers Roberto Castilla López and Llorenç Macià have developed a numerical simulator using OpenFOAM in order to analyze the flow inside a supersonic ejector. They have found that a one dimensional solver (1D model) of the steady flow is needed to interact with the larger and more complex transient solver that is already done. This OpenFOAM CFD solver will allow to find coefficients to adjust the performance of the one dimensional solver. Then, the 1D solver will be used for the optimization process, as it will allow to make a higher number of simulations. The problem with the CFD solver is that, due to its complexity, every simulation takes too much time, making it impossible to carry out an optimization process. Therefore, the development of a one dimensional solver has been done using Python. The model is capable to compute the performance for a given ejector geometry and to approximate the vacuum level that can be reached

Sympathetic Arousal During Approach-Avoidance Decision- Making

Title from PDF of title page, viewed on August 12, 2015Thesis advisor: Robin AupperleVitaIncludes bibliographic references (pages 43-47)Thesis (M.A.)--Department of Psychology. University of Missouri--Kansas City, 2015In response to emotional stimuli, individuals exhibit increased sympathetic nervous firings, which stimulate eccrine gland activation. This eccrine activity changes the electrical properties of the skin, or electrodermal activity (EDA). EDA has been used widely to assess autonomic arousal during various paradigms. Research has demonstrated how autonomic arousal (1) occurs during the processing or anticipation of emotional stimuli and (2) may inform the decision-making process. Our research focused on investigation of sympathetic arousal during decisions involving conflicting emotional outcomes, using an approachavoidance processing paradigm. In these situations, individuals are faced with two emotionally valenced outcomes, typically one positive and one negative. However, if the negative outcome is chosen, the individual is given a reward; by this the individual experiences emotional conflict – they can approach the conflict, and receive a reward while experiencing a negative emotion, or they can avoid the conflict by choosing the positive outcome, which is not associated with a reward. Results suggest that sympathetic arousal during these decisions is influenced by potential reward, degree of choice certainty, and an individuals aversion to negative experiences. Sympathetic arousal increased with larger potential reward, and individuals who expressed more uncertainty in their desired outcome exhibited larger emotional responses when making decisions.Introduction -- Review of literature -- Methods -- Results -- Discussio

Phase Shifter for Millimeter-Wave Frequency Range Based on Glide Symmetric Structures

The use of glide symmetry in radiofrequency devices to introduce dispersive effects has been recently proposed and demonstrated. One of these effects is to control the propagation constant of the structure. Here, we propose a mm-wave phase shifter whose elements have a glide-symmetric configuration to achieve a greater phase shift in the same waveguide space than the non-glide-symmetric case. The glide-symmetric phase shifter is implemented in waveguide technology and is formed by rows of metallic pins that produce the desired phase shift. To assess the better performance of the glide-symmetric phase shifter, it is compared to its non-glide-symmetric version whose metallic pins are located only in one of the broad sides of the waveguide. The operating frequency range of the phase shifter is 67 to 75 GHz. Results show a 180 degree phase shift in regard to the reference waveguide without pins, and 50 degrees more than the non-glide-symmetric version.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Instrumentation for solar spectropolarimetry: state of the art and prospects

Given its unchallenged capabilities in terms of sensitivity and spatial resolution, the combination of imaging spectropolarimetry and numeric Stokes inversion represents the dominant technique currently used to remotely sense the physical properties of the solar atmosphere and, in particular, its important driving magnetic field. Solar magnetism manifests itself in a wide range of spatial, temporal, and energetic scales. The ubiquitous but relatively small and weak fields of the so-called quiet Sun are believed today to be crucial for answering many open questions in solar physics, some of which have substantial practical relevance due to the strong Sun?Earth connection. However, such fields are very challenging to detect because they require spectropolarimetric measurements with high spatial (sub-arcsec), spectral (<100  mÅ), and temporal (<10  s) resolution along with high polarimetric sensitivity (<0.1  %   of the intensity). We collect and discuss both well-established and upcoming instrumental solutions developed during the last decades to push solar observations toward the above-mentioned parameter regime. This typically involves design trade-offs due to the high dimensionality of the data and signal-to-noise-ratio considerations, among others. We focus on the main three components that form a spectropolarimeter, namely, wavelength discriminators, the devices employed to encode the incoming polarization state into intensity images (polarization modulators), and the sensor technologies used to register them. We consider the instrumental solutions introduced to perform this kind of measurements at different optical wavelengths and from various observing locations, i.e., ground-based, from the stratosphere or near space.Fil: Iglesias, Francisco Andres. Universidad Tecnológica Nacional. Facultad Regional de Mendoza; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaFil: Feller, Alex. Max Planck Institut Fur Sonnensystemforschung; Alemani

Measuring iron deposits within focal lesions in patients presenting clinically isolated syndrome

Postprint (author's final draft