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CHARA/MIRC Observations of Two M supergiants in Perseus OB1: Temperature, Bayesian Modeling, and Compressed Sensing ImagingBaron, F., Monnier, J. D., Kiss, L. L., Neilson, H. R., Zhao, M., Anderson, M., Aarnio, A., Pedretti, E., Thureau, N., Ten Brummelaar, T. A., Ridgway, S. T., McAlister, H. A., Sturmann, J., Sturmann, L., Turner, N. 10 April 2014 (has links)
Two red supergiants (RSGs) of the Per OB1 association, RS Per and T Per, have been observed in the H band using the Michigan Infra-Red Combiner (MIRC) instrument at the CHARA array. The data show clear evidence of a departure from circular symmetry. We present here new techniques specially developed to analyze such cases, based on state-of-the-art statistical frameworks. The stellar surfaces are first modeled as limb-darkened disks based on SATLAS models that fit both MIRC interferometric data and publicly available spectrophotometric data. Bayesian model selection is then used to determine the most probable number of spots. The effective surface temperatures are also determined and give further support to the recently derived hotter temperature scales of RSGs. The stellar surfaces are reconstructed by our model-independent imaging code SQUEEZE, making use of its novel regularizer based on Compressed Sensing theory. We find excellent agreement between the model-selection results and the reconstructions. Our results provide evidence for the presence of near-infrared spots representing about 3%-5% of the stellar flux.
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Evaporation Enhancement for Condensational Nanoparticle Growth in Hydrophobic Evaporation - Condensation TubeLiang, Huayan 13 October 2014 (has links)
No description available.
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An ALMA and MagAO Study of the Substellar Companion GQ Lup BWu, Ya-Lin, Sheehan, Patrick D., Males, Jared R., Close, Laird M., Morzinski, Katie M., Teske, Johanna K., Haug-Baltzell, Asher, Merchant, Nirav, Lyons, Eric 22 February 2017 (has links)
Multi-wavelength observations provide a complementary view of the formation of young, directly imaged planetmass companions. We report the ALMA 1.3 mm and Magellan adaptive optics H alpha, i', z', and YS observations of the GQ Lup system, a classical T Tauri star with a 10-40 M-Jup substellar companion at similar to 110 au projected separation. We estimate the accretion rates for both components from the observed Ha fluxes. In our similar to 0.'' 05 resolution ALMA map, we resolve GQ Lup A's disk in the. dust continuum, but no signal is found from the companion. The disk is compact, with a radius of similar to 22 au, a dust mass of similar to 6M(circle plus), an inclination angle of similar to 56 degrees, and a very flat surface density profile indicative of a radial variation in dust grain sizes. No gaps or inner cavity are found in the disk, so there is unlikely a massive inner companion to scatter GQ Lup B outward. Thus, GQ Lup B might have formed in situ via disk fragmentation or prestellar core collapse. We also show that GQ Lup A's disk is misaligned with its spin axis, and possibly with GQ Lup B's orbit. Our analysis on the tidal truncation radius of GQ Lup A's disk suggests that GQ Lup B's orbit might have a low eccentricity.
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[en] INTERFEROMETRIC LINEAR LASER MEASURING SYSTEM CALIBRATION BY COMPARATIVE METHOD / [pt] IMPLEMENTAÇÃO E VALIDAÇÃO DE MÉTODO COMPARATIVO DE CALIBRAÇÃO DE SISTEMA DE MEDIÇÃO LINEAR POR INTERFEROMETRIA LASERWELLINGTON SANTOS BARROS 24 June 2003 (has links)
[pt] O presente trabalho tem por objetivo implantar um método
para calibração de sistema de medição linear por
interferometria laser por meio de comparação a um outro
sistema laser de referência. O referido método é
considerado mais simples que a calibração por componentes
realizada atualmente e, conforme demonstrado no trabalho,
apresenta confiabilidade metrológica que atende a
exatidão necessária para as aplicações dos laseres em
metrologia dimensional, vindo suprir uma necessidade
metrológica dos laboratórios credenciados pelo Instituto
Nacional de Metrologia, Normalização e Qualidade Industrial
(Inmetro) e do parque industrial brasileiro, usuários
destes sistemas de medição. A implantação do sistema para
calibração de lasers de medição foi baseada em normas
internacionais de calibração e de cálculo da incerteza de
medição e utilizou um sistema laser de referência calibrado
no Inmetro, com rastreabilidade a padrões nacionais, com as
menores incertezas possíveis. O método de medição
implantado realiza a calibração de um sistema laser por
comparação a outro utilizando medições feitas a partir do
deslocamento da mesa onde é a apoiado o prisma óptico. O
que é de fato analisado é a diferença das medições dos dois
sistemas laser para um mesmo deslocamento. Foram
registradas as diferenças das indicações de 200 mm em 200
mm de deslocamento, em um total de 2000 mm, que variaram de
0,027 µm a 0,690 µm. Foram realizadas três medições para
cada deslocamento e quatro repetições completas do
procedimento em dias diferentes, com variação do desvio
padrão de 0,009 µm a 0,098 µm e incertezas expandidas
que variaram de 0,109 µm a 0,306 µm. São apresentadas a
metodologia de calibração, cálculos das correções, fontes
de erros e cálculos da incerteza de medição para a
comparação de sistemas laseres de medição linear. / [en] The present work aims at the implementation of a
calibration method for interferometric linear laser
measurement systems by comparison to another reference
system. The proposed method is considered simpler than the
calibration by components that is carried out today at
Inmetro (National Institute of Metrology, Standardization
and Industrial Quality) and, as demonstrated along
this work, presents the metrological reliability and
accuracy necessary for several applications of lasers in
dimensional metrology. This approach will supply the
metrological needs of several laboratories accredited by
Inmetro and of the Brazilian industry in general, users of
such measurement systems, regarding cost and time of
calibration. The method implemented was based on
international technical standards related to calibration
and uncertainty calculation and used a reference system
calibrated at Inmetro, with traceability to national
standards, with the lowest uncertainties that could be
achieved. The said method performs the calibration of a
laser system by comparison to another through measurements
of the displacement of the table where the optical prism
rests. What is indeed analyzed is the difference of the
measurements obtained by the two laser systems for the same
table displacement. The differences were recorded for each
displacement of 200 mm, in a total of 2,000 mm, their
variation being from 0.027 µm to 0.690 µm. The whole
procedure was repeated four times, in different days,
with three measurements for each displacement. Their
standard deviation varied from 0.009 µm to 0.098 µm while
their expanded uncertainties varied from 0.109
µm to 0.306 µm depending on the value of the displacement.
The calibration methodology, correction calculation, errors
sources and measurement uncertainty calculations for the
linear measurement laser systems comparison are presented in
this dissertation.
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Above-ground biomass estimation in boreal productive forests using Sentinel-1 dataRoc Roc, David January 2019 (has links)
Estimation of biomass has high importance for economic, ecologic and climatic reasons due to the multiple ecosystem services offered by forested landscapes. Measurements that are taken in the field incur personal and economic costs. Nevertheless, biomass surveying based on remote sensing techniques offer efficiency thanks to covering large areas. The European Space Agency (ESA) Sentinel-1 satellite offers promising capabilities for above-ground biomass (AGB) estimation through synthetic aperture radar (SAR) based microwave remote sensing. In this study, experimental AGB estimations based on Sentinel-1 C-band data were produced over the Remingstorp estate (Västergötland County, Sweden) to analyze its performance over boreal productive forests. The obtained measurements were compared against reference values obtained by combining photogrammetric, aerial laser scanning (ALS) and field measurements. Thus, a reference high-resolution canopy height model (CHM) was produced from the difference between photogrammetric digital surface model (DSM) values and ALS digital terrain model (DTM) values. The comparison of CHM observations against diameter at breast height (DBH) field measurements revealed the existence of a vegetation height - vegetation volume relationship for the study species (Pinus Sylvestris and Picea Abbies), which allowed bole volume estimation based on vegetation height values. SAR-based AGB estimates were produced by defining statistical relationships between backscatter intensity and interferometric coherence measurements against reference CHM values. Additionally, evaluation of biomass estimation through interferometric (InSAR) height was possible by comparing against reference photogrammetric DSM. Backscatter signal saturation of C-band at low biomass volumes prevented quantification of biomass but permitted differentiation between forested and non-forested surfaces. Estimation of AGB through interferometric coherence was possible through modeling volumetric decorrelation, which on the contrary prevented biomass retrieval from InSAR height. Due to the given frequency properties at C-band, HV cross-polarized channel was used in all cases for better detection of the canopy layer. Image acquisition under stable conditions was a priority to avoid noise derived from variable dielectric properties, acquisition geometry effects and temporal decorrelation. Hence, image acquisitions under stable hydrometeorological conditions (i. e. stable frozen or dry) and for the lowest repeat-pass interval (i. e. 6-days) were prioritized.
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Evolution of IR Absorber for Integration in an IR Sensitive CO2 DetectorAshraf, Shakeel January 2011 (has links)
The maximum sensitivity of a thermal IR sensor can be available either by means of the sensor material, having its own absorbing properties, or by the deposition of an additional absorber structure on the detector surface. In this thesis, the theory of two absorption structures is discussed. The first is called the interferometric absorber structure. The second structure under investigation uses a lead selenide layer for the IR absorption. In the interferometric structure, a new epoxy material SU8-2002 was used as a dielectric medium. This material has a very low thermal conductivity of 0.3 W/mK, which makes it suitable for thermal detectors. The interferometric structure is based on three layers, a 40–60 Å thick Ti layer, a SU8–2002 layer with a thickness of 2000 Å thick and a 2000Å Al layer. Using standard cleanroom processing an interferometric structure was fabricated. Transfer matrix theory was used in order to simulate the interferometric structure and the lead selenide was fabricated by means of an argon-plasma sputtering process. Both fabricated samples were characterized through Fourier transfer infrared (FTIR) spectroscopy together with a specular reflectance accessory. The thicknesses of the added layers were measured using Atomic force microscopy (AFM) for both the interferometric and lead selenide structure. It was determined that by changing the reflective index value of the SU8-2002 from the reported value of 1.575 to about 2.40 that this provided a better agreement with the experimental results. The absorption results for the interferometric structure were determined to be approximately 82–98% for the wavelength region of 2-20µm at 30 degree. The PbSe absorption spectra showed 30%–50% absorption for the wavelength region 2.5 – 6.67μm.
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Parametric Investigation Of Spray Characteristics Using Interferometric Particle Imaging TechniqueOcer, Nuri Erkin 01 December 2009 (has links) (PDF)
Spray is an efficient tool in the usage whose primary objectives are to obtain droplets with increased liquid surface area and more dispersed liquid over a larger volume. The determination of spray characteristics has been a topic of extensive research recently. In the present investigation, the flow structure of a spray issuing from an oil burner nozzle was determined in a parametrical manner. The main tool in the experimental research is the Interferometric Particle Imaging (IPI) configuration. This method exploits the interference between light reflected from and refracted through individual transparent spray droplets which are illuminated by a laser light sheet in a wide angle forward-scatter region. Based on a scattering theory, the droplet diameter of spray particles can be related to the light pattern scattered from that particle. In addition, using double-framed images also enables the calculation of velocities associated with these particles. In this way, as a representation of spray structure, the droplet size and velocity distributions were obtained prior to a change in the primary parameters of liquid flow e.g. surface tension, viscosity, density and the injection pressure. The evolution of spray characteristics in space were also examined by conducting
measurements in different radial and axial locations relative to spray centerline.
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Ground Deformation Related to Caldera Collapse and Ring-Fault ActivityLiu, Yuan-Kai 05 1900 (has links)
Volcanic subsidence, caused by partial emptying of magma in the subsurface reservoir has long been observed by spaceborne radar interferometry. Monitoring long-term crustal deformation at the most notable type of volcanic subsidence, caldera, gives us insights of the spatial and hazard-related information of subsurface reservoir. Several subsiding calderas, such as volcanoes on the Galapagos islands have shown a complex ground deformation pattern, which is often composed of a broad deflation signal affecting the entire edifice and a localized subsidence signal focused within the caldera floor. Although numerical or analytical models with multiple reservoirs are proposed as the interpretation, geologically and geophysically evidenced ring structures in the subsurface are often ignored. Therefore, it is still debatable how deep mechanisms relate to the observed deformation patterns near the surface. We aim to understand what kind of activities can lead to the complex deformation. Using two complementary approaches, we study the three-dimensional geometry and kinematics of deflation processes evolving from initial subsidence to later collapse of calderas. Firstly, the analog experiments analyzed by structure-from-motion photogrammetry (SfM) and particle image velocimetry (PIV) helps us to relate the surface deformation to the in-depth structures. Secondly, the numerical modeling using boundary element method (BEM) simulates the characteristic deformation patterns caused by a sill-like source and a ring-fault. Our results show that the volcano-wide broad deflation is primarily caused by the emptying of the deep magma reservoir, whereas the localized deformation on the caldera floor is related to ring-faulting at a shallower depth. The architecture of the ring-fault to a large extent determines the deformation localization on the surface. Since series evidence for ring-faulting at several volcanoes are provided, we highlight that it is vital to include ring-fault activity in numerical or analytical deformation source formulation. Ignoring the process of ring-faulting in models by using multiple point sources for various magma reservoirs will result in erroneous, thus meaningless estimates of depth and volume change of the magmatic reservoir(s).
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Fázové zobrazování pod difrakčním limitem / Phase imaging below the diffraction limitNečesal, Daniel January 2020 (has links)
Tato diplomová práce se zabývá konstrukcí interferenčních zařízení pro výzkum měření fáze světla na mikro-strukturách a fáze plazmonů na nano-strukturách. V první kapitole je vybudován teoretický základ pro optiku a nano-fotoniku používané v budoucích kapitolách. Následně je popsána interference vln a jejich praktické použití pro prolomení difrakčního limitu pomocí holografie plazmonů. Prvním experimentální sestavou je Machův-Zehnderův holografický mikroskop. Je popsán způsob, jak ho sestavit z běžně dostupných součástek a jak je navržen ovládací software k jeho používání. Následně jsou popsány výsledky naměřené pomocí tohoto zařízení. V poslední kapitole se zaměříme na sestavení holografického SNOM přístroje pro studování plazmonů a jejich interference. Nejdříve popíšeme základní princip a navržení softwaru pro automatizaci měření, pro zrychlení vědeckých postupů. Nakonec předložíme výsledky měření mikroskopu.
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Deep learning and quantum annealing methods in synthetic aperture radarKelany, Khaled 08 October 2021 (has links)
Mapping of earth resources, environmental monitoring, and many other systems require high-resolution wide-area imaging. Since images often have to be captured at night or in inclement weather conditions, a capability is provided by Synthetic Aperture Radar (SAR). SAR systems exploit radar signal's long-range propagation and utilize digital electronics to process complex information, all of which enables high-resolution imagery. This gives SAR systems advantages over optical imaging systems, since, unlike optical imaging, SAR is effective at any time of day and in any weather conditions. Moreover, advanced technology called Interferometric Synthetic Aperture Radar (InSAR), has the potential to apply phase information from SAR images and to measure ground surface deformation. However, given the current state of technology, the quality of InSAR data can be distorted by several factors, such as image co-registration, interferogram generation, phase unwrapping, and geocoding.
Image co-registration aligns two or more images so that the same pixel in each image corresponds to the same point of the target scene. Super-Resolution (SR), on the other hand, is the process of generating high-resolution (HR) images from a low-resolution (LR) one. SR influences the co-registration quality and therefore could potentially be used to enhance later stages of SAR image processing. Our research resulted in two major contributions towards the enhancement of SAR processing. The first one is a new learning-based SR model that can be applied with SAR, and similar applications. A second major contribution is utilizing the devised model for improving SAR co-registration and InSAR interferogram generation, together with methods for evaluating the quality of the resulting images.
In the case of phase unwrapping, the process of recovering unambiguous phase values from a two-dimensional array of phase values known only modulo $2\pi$ rad, our research produced a third major contribution. This third major contribution is the finding that quantum annealers can resolve problems associated with phase unwrapping. Even though other potential solutions to this problem do currently exist - based on network programming for example - network programming techniques do not scale well to larger images. We were able to formulate the phase unwrapping problem as a quadratic unconstrained binary optimization (QUBO) problem, which can be solved using a quantum annealer. Since quantum annealers are limited in the number of qubits they can process, currently available quantum annealers do not have the capacity to process large SAR images. To resolve this limitation, we developed a novel method of recursively partitioning the image, then recursively unwrapping each partition, until the whole image becomes unwrapped. We tested our new approach with various software-based QUBO solvers and various images, both synthetic and real. We also experimented with a D-Wave Systems quantum annealer, the first and only commercial supplier of quantum annealers, and we developed an embedding method to map the problem to the D-Wave 2000Q_6, which improved the result images significantly. With our method, we were able to achieve high-quality solutions, comparable to state-of-the-art phase-unwrapping solvers. / Graduate
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