INANOE Repositorio (Inst- Nacional de Astrofísica, Óptica y Electrónica
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CanHiS: very high resolution capability for the OAGH
Get PDFIn this work we present the characterization and coupling process of the Cananea
High-Resolution Spectrograph (CanHiS) of the Observatorio Astrofísico Guillermo Haro
(OAGH), at Cananea, Sonora, from the acquisition of the instrument at the University
of Arizona (UA), until its commissioning at the OAGH and the observation of the first
spectra of stellar objects, aimed at determining the abundances of individual chemical
species.
We first carried out a complete characterization of the opto-mechanical CanHiS
properties and optical performance analysis, culminating with a comprehensive optomechanical
simulation of the spectrograph, and we showed the advantages offered by
CanHiS. Its principal feature is the adjustable quasi-Littrow mounting, that, combined
with the use of medium-band interference filters, makes CanHiS an instrument with
very high spectral resolution capabilities and efficiency (R ≈ 85000 − 190000, and
∼ 36%, respectively). Since the original opto-mechanical specifications were incomplete
and not precise, we carried out a complete and detailed characterization of the whole
instrument. Finally, we conducted an analytical study of the expected performance and
we compared it with the results of a commisioning observing run, showing an excellent
match.
Once CanHiS became fully operational at the OAGH, it was used to conduct, as
part of its first scientific program, observations of the 6707.7 Å lithium line in a small
set of 12 solar-type stars —spectral type between G0-G3, and luminosity class V—,
bright enough to allow sensitive observations at high spectral resolution with CanHiS.
We also performed a theoretical study of spectroscopic indices as tools for the determination
of the leading atmospheric parameters of Sun-like stars, and we demonstrated
the capabilities of diagnostic diagrams of theoretical indices in the determination of effective
temperature and surface gravity. The diagrams were constructed after analyzing
all possible index-index combinations of a variety of spectral features in the wavelength
region 3800−4700 Å, observed at a moderate spectral resolution (FWHM 2.5 Å). Aimed
at validating the proposed technique, we applied a set of diagnostic diagrams to a selected
sample of 40 stars of M 67 and found that, under the assumption of solar chemical
composition (perfectly compatible with the metallicity of M 67), we obtain a set of atmospheric parameters consistent with those determined from high resolution studies.Se presenta el proceso de actualización y caracterización del espectrógrafo CanHiS
(Cananea High-Resolution Spectrograph), actualmente en operación en el Observatorio
Astrofísico Guillermo Haro (OAGH). El proceso incluye desde que se adquirió el
instrumento (donado por la Universidad de Arizona), hasta su entrada en operación y
primer campaña observacional en el OAGH, dedicado a la determinación de abundancias
químicas en estrellas de tipo solar.
Lo primero que se realizó fue una re-caracterización opto-mecánica completa del
espectrógrafo y el análisis de su desempeño óptico, que culminó con una simulación
integral (óptica y mecánica) del instrumento, mostrando las ventajas de su singular
configuración óptica, la montura Quasi-Littrow, que combinada con el uso de filtros de
paso de banda, en vez de un dispersor cruzado, generan una muy alta resolución espectral
(R ≈ 85000 − 190000) con una eficiencia muy elevada (∼ 36%). Posteriormente
se realizó un estudio analítico del desempeño esperado del espectrógrafo (adaptado al
telescopio de 2.1-m del OAGH), incluyendo una simulación óptica, y se comparó con el
desempeño real del instrumento, mostrándose el excelente desempeño óptico de CanHiS,
muy parecido a los resultados esperados.
Una vez que el instrumento entró en operaciones en el OAGH, como parte de sus
primer programa científico observacional, se enfocó en el análisis en la línea de Litio
a 6707.7 Å (algunas veces muy débil y por lo tanto difícil del observar, como en el
caso del Sol), en una pequeña muestra de 12 estrellas de tipos solar, lo suficientemente
brillantes para poder ser observadas a alta resolución con CanHiS.
Se realizó además un estudio teórico sobre índices espectroscópicos como herramientas
en la determinación de los parámetros atmosféricos principales de estrellas de tipo
solar, y se mostró el potencial de diagramas de diagnóstico formados por estos índices
teóricos en la determinación de la temperatura efectiva y la gravedad. Los diagramas
se construyeron luego de analizar todas las posibles combinaciones de índices de una
variedad de líneas espectrales en una región de longitud de onda entre 3800−4700 Å,
observadas a una resolución espectral intermedia de 2.5 Å. Para probar la validez de
esta técnica, se aplicaron dichos diagramas de diagnóstico a una muestra de 40 estrellas
del cúmulo abierto M 67, cerca del turn-off de este cúmulo, y se encontró que, bajo
la consideración de poseer metalicidad sola
Collinear acousto-optical filters controlled by acoustic waves of finite amplitude
Get PDFNew physical aspects of collinear acousto-optical interaction, occurred by acoustic waves of finite amplitude, are revealed and analyzed in crystalline materials exhibiting moderate linear acoustic losses. The analysis is performed in the regime of continuous traveling waves allowing specific mechanism of the acousto-optic nonlinearity. Our consideration has shown that such nonlinearity together with linear acoustic losses is able to affect the transmission function inherent in collinear interaction. In particular, the mere presence of linear acoustic losses by themselves leads to broadening the width of transmission function beginning already from very low levels of the applied acoustic power. Moreover, the transmission function exhibits a marked and quasi-periodical dependence on the applied acoustic power density; and that periodicity is governed by the linear acoustic losses. As a result, the transmission function can be significantly narrowed near isolated points at the cost of decreasing the interaction efficiency. These novelties related to collinear acousto-optical interaction accompanied by moderate linear acoustic losses have been studied and confirmed experimentally with two advanced acousto-optical cells based on calcium molybdate (CaMoO4) single crystal and lithium niobate (LiNbO3), which are controlled by acoustic waves of finite amplitude. For the lithium niobate cell we examine the phenomena affecting the filter transmission efficiency and its spectral resolution, namely, the light-induced absorption and photorefraction. The highest available spectral resolution attains δλ = 0.15 Å at λ = 370 nm (the resolving power R ~ 25000), with an efficiency of 11%, or δλ = 0.18 Å at λ = 532 nm (R ~ 30000), with an efficiency of 33%
Diseño de filtros adaptativos basados en modelos LTV
No full textLa presente tesis trata acerca del diseño de filtros adaptativos que usan como estructura
filtros con parámetros variantes en el tiempo. Estos filtros están caracterizados por tener
una respuesta transitoria de duración reducida comparada con la respuesta de filtros que
no varían sus parámetros.
Un aspecto importante del desempeño dinámico de los filtros con parámetros variantes
en el tiempo son sus propiedades de estabilidad. Estos filtros no solamente deben ser
estables en la ausencia de una señal de entrada, pero además deben generar una respuesta
acotada a una entrada acotada. Esta propiedad los hace buenos candidatos para
servir como estructura en esquemas de filtrado adaptativo
EEG/ECoG-based BCI systems: a NeuroFuzzy approach using recurrent neural networks and adaptive filters
Get PDFA brain computer interface (BCI) is a system aimed to provide the brain with
an additional channel of communication and control, which does not depend
on the normal output pathways. This dissertation is focused on the study of
signal processing techniques to address two issues of current BCI methodologies.
These issues are related to spatial filtering techniques and approaches
for capturing temporal behavior of electrical brain signals recorded through two
different modalities: Electroencephalography (EEG) and electrocorticography
(ECoG). Concerning to spatial filtering, a non-supervised algorithm based on
the steepest descent method to adapt spatial filter’s coefficients for preprocessing
ECoG signals is proposed
Strategic interactions against non-stationary agents
Get PDFDesigning an agent that is capable of interacting with another agent is an open problem. An
interaction happen when two or more agents perform an action in an environment and they obtain
an utility based on the performed joint action.Current multiagent learning techniques do not fare
well with agents that change their behavior during a repeated interaction. This happens because
they usually do not model the other agents’ behavior and instead make some assumptions that for
real scenarios are too restrictive. Furthermore, considering that many applications demand different
types of agents to work together this should be an important problem to solve. It does not matter if
the domain is cooperative (where agents have a common goal) or competitive (where objectives are
different), there is one common aspect: agents must learn how their counterpart is acting and react
quickly to changes in behavior
Propuesta para el cálculo de ganancia de RF como figura de mérito de un enlace fotónico
Get PDFEste trabajo de tesis está ubicado en el área de las comunicaciones ópticas,
específicamente en la disciplina llamada fotónica de microondas. Se analiza un enlace
fotónico particular con el propósito de modelar y proponer una expresión matemática para
el cálculo de ganancia de radiofrecuencia, a fin de que sea utilizada como una figura de
mérito de un sistema de comunicación basado en el filtro fotónico. Desde el punto de vista
de la fotónica de microondas, un filtro fotónico se define como un subsistema que permite
realizar tareas similares a las de un filtro eléctrico, mediante la utilización de dispositivos
electro-ópticos. La respuesta en frecuencia del filtro fotónico se caracteriza por una serie de
ventanas pasabanda que pueden utilizarse como sub-portadoras de información eléctrica
Measurement of blood flow and assessment of breast health by using non-invasive optical techniques
Get PDFLaser Speckle Imaging (LSI) is an optical technique used to generate blood flow maps
with high spatial and temporal resolution. A modified laser speckle imaging (mLSI) enables
computation of blood flow maps with relatively high spatial resolution. Although
it is known that the sensitivity and noise in LSI measurements depend on image exposure
time, a fundamental disadvantage of mLSI is that it does not take into account this
parameter. In this thesis, the exposure time into the mLSI method was integrated and
provides experimental support for this approach with measurements from an in vitro
flow phantom. In the other hand it is well known that in LSI, the speckle size must
exceed the Nyquist criterion to maximize the speckle’s pattern contrast. The effect of
speckle-pixel size ratio not only in dynamic speckle contrast, but also on the calculation
of the relative flow speed for temporal and spatial analysis was studied as well.
Data suggest that the temporal LSCI algorithm is more accurate at assessing the relative
changes in flow speed than the spatial algorithm. Quantify the probabilities for women
to develop breast cancer in the future or harbour breast cancer, via their bulk optical
tissue properties is the objective of the clinical research in the Ontario Cancer Institute,
Canada. As a part of this research, based on measurements of trans-illumination
spectroscopy breast tissue from participants of the clinical research, hemoglobin, oxygenated
hemoglobin, collagen, lipids and water concentration and the scattering value
were obtained by using the equation diffusion in this thesis work
Generación de chorros de agua mediante termocavitación en tubos capilares
Get PDFLa cavitación es un fenómeno que su estudiado fue motivado por el daño provocado en hélices de los barcos por la onda de choque generada por el colapso de las burbujas. Por tal motivo fue un fenómeno no deseado, que ahora se le han encontrado aplicaciones útiles. En el presente trabajo se estudia la cavitación para producir chorros de agua a alta velocidad para ser usados en aplicaciones médicas como es la inyección de medicamentos sin aguja.
La palabra cavitación derivada del latín “cavus” que significa hueco o vacío. Puede definirse como el estudio de la formación, crecimiento y colapso de una burbuja compuesta por gases o vapores en un fluido. En el momento del colapso de la burbuja, se produce una onda de choque con una presión muy grande. La onda de choque lleva una gran cantidad de energía mecánica que puede causar un daño enorme en superficies cercanas como por ejemplo en las propelas de los barcos o en tuberías donde circula líquido a gran velocidad. Gracias al efecto destructivo producido se comenzó a estudiar la cavitación
Study of intrinsic properties of HII galaxies at high redshift
Get PDFI have selected a sample of 504 HII like-starburst galaxies according to the equivalent
widths in their emission lines in a range of redshift of 0.1 < z < 3.4 from the literature,
in order to assess the validity of the L(HB) - g relation at high redshift and its use
as an accurate distance estimator. The physical parameters for the sample at high
redshift, within the uncertainties, are consistent with the ones for the HIIGx at low
redshift. This suggests that the physical properties for HIIGx at low and high redshift
are similar.
By combining our sample at high redshift with the local sample of HIIGx from Chávez
et al. (2014), I find an evident flattening that starts at approximately log(g) = 1:8 km
s-1 in the L(HB) - g relation. This flattening has an interesting application since it
leads to a kind of standard candle for those HIIGx with log(g) > 1:8 km s-1. This
flattening or the existence of an upper limit in the luminosity of HIIGx has not been
reported before. Applying this new HIIGx standard candle method to the high redshift
sample we obtain good restrictions on the cosmological parameters solution space.
The combination of our sample at high redshift with the local sample of 156 (HIIGx
and GEHRs) dramatically improves the constraints on the plane (nm, w0), which are
consistent with the results from SNeIa.
These results are surprisingly good considering the high uncertainties in the data at
high redshift, therefore we expect better constraints on the plane (nm, w0) using high
quality data from high resolution spectrographs at 8 m class telescopes
Inversor ingenuo y concurrencia para un sistema qutrit entrelazado
Get PDFSe caracteriza el entrelazamiento cuántico en un sistema bipartita de qutrits usando la
medida de concurrencia. Para ello, pretendemos construir un inversor ingenuo que gira el
espín del qutrit, con ayuda de las matrices de Gell-Mann. Sin embargo, se presentan problemas
en la caracterización de cierto tipo de estados. Por lo tanto, proponemos una mejor
forma de obtener la matriz de densidad del espín girado bajo la acción de súper operadores
definidos a partir de las mismas matrices.
Comparamos los resultados para obtener la concurrencia, mostrando que el inversor ingenuo
entrega información equivalente al inversor exacto sólo en algunos casos