Orientador: Inacio Maria Dal Fabbro / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-08T06:46:24Z (GMT). No. of bitstreams: 1 Vieira_MarcioAlexandrePinto_M.pdf: 3890763 bytes, checksum: ec176daee99c277e022ce62c1efe297e (MD5) Previous issue date: 2005 / Resumo: O fenômeno de vibração é de ocorrência comum na mecânica, geralmente associado à membros estruturais assim como elementos de maquinas. Particularmente, no campo da engenharia agrícola, vibração vem associada à ferimentos em vegetais nas operações de campo, que claramente inclui colheita, transporte e processamento. A escolha de membros estruturais simples, como as viga engastada, para validar o método, quando uma estrutura mais complexa for ser considerada. O nome moiré tem sua origem na língua francesa, referindo-se ao padrão de onda formado. O fenômeno é gerado quando telas são sobrepostas, produzindo padrões de ondas ou franjas, que se movem quando suas posições relativas são alteradas. O método selecionado é chamado método geométrico de moiré, que consiste em projetar uma grade sobre a superfície do objeto em estudo e superpor a foto original e a grade deformada. Software's especificos são empregados na análise de imagens. O objetivo do presente trabalho é determinar o deslocamento transversal da linha elástica na Teoria da viga engastada de Euler-Bernoulli, excitada por um excitador eletromagnético, utilizado em analise modal, utilizando a técnica de moiré descrita acima / Abstract: Vibration phenomena are of common occurrence in mechanics, generally associated to structural members as well as to machine elements. Particularly, in the field of agricultural engineering, vibration comes also associated to vegetable bruising during field operations, which clearly includes harvesting, transportation and processing. The selection of a simple structural member as a cantilever beam to support the utility of a moiré technique in studying vibration analysis is to validate the method when more complex structures are being considered. Vibration modes of a cantilever beam are easily determined by analytical methods. The name moiré has its origin in the French language, referring to wave like pattern. The phenomenon is generated when screens superposed, producing wave like patterns or fringes, which move when its relative positions are displaced. The selected method is named geometric moiré, which consists in projecting a grid onto the object in study and superposing both, the original and the deformed grid. Specific software's were employed in the image analysis. The objective of the present work is to determine the transversal displacement of the elastic line of Euler-Bernoulli cantilever beam being excited by an electromagnetic varying field using the moiré technique described above. Keywords: vibration, geometric moiré / Mestrado / Projetos, Desenvolvimento e Otimização de Maquinas Agricolas / Mestre em Engenharia Agrícola

Where the evaluation of the mechanical properties and behaviour of building materials is concerned, there is still not a universally accepted solution for making such measurements. Optical diagnostic techniques are particularly attractive for a non-destructive evaluation of a surface's state and the detection of incipient damage. Non-contact, high precision measurements and full-field of observation are features that can bring enormous advantages in experimental tests.

No description available.

In this thesis I discuss my work on the Arcminute Microkelvin Imager (AMI). I focus on the detection of Sunyaev-Zel'dovich (SZ) signatures at 14-18GHz. Once the background science and operation of the instrument are described I proceed to present my contribution to the calibration of AMI, including: primary beam measurements; refinements to the known antenna geometry and flagging geostationary satellite interference. This is followed by an outline of the software that I have developed to subtract sources from visibilities, concatenate data from multiple observations, simulate data, and perform jack-knife tests to evaluate the magnitude of systematic errors. The Bayesian analysis that I use to obtain parameter estimates and to quantify the significance of putative SZ detections is described. I perform realistic simulations of clusters and use these to characterisethe analysis. I then, for the first time, apply the analysis to data from the AMI blind cluster survey. I identify several previously unknownSZ decrements. Finally, I conduct pointed observations towards a high luminosity subsample of eight clusters from the Local Cluster Substructure Survey(LoCuSS). For each of these I provide probability distributions of parameters such as mass, radius, and temperature. I compare myresults to those in the literature and find an overall agreement.

Orientador: Max Henrique Machado Costa / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-24T13:29:51Z (GMT). No. of bitstreams: 1 Bins_LeonardoSant'Anna_D.pdf: 7799361 bytes, checksum: 9e2474fa080f4e6f30dd2971af9cd670 (MD5) Previous issue date: 2014 / Resumo: Dois problemas importantes na interferometria SAR (Synthetic Aperture Radar) são a estimação da fase absoluta e das linhas de base. O conhecimento preciso da fase absoluta e das linhas de base são fundamentais para a geração de modelos digitais de superfície ou terreno com alta precisão planimétrica e altimétrica. A estimação de fase absoluta consiste de duas etapas. A primeira etapa efetua o desdobramento da fase, o qual recupera a fase absoluta com os correspondentes múltiplos de 2?. A segunda etapa consiste na estimação do deslocamento de fase, causada pela combinação de erros de sincronização no sistema de aquisição de dados com erros de processamento da Interferometria SAR (InSAR). A estimação de linha de base consiste na determinação da posição da antena escrava relativa à posição da antena mestre (ou antena de referência). As contribuições desta tese consistem na concepção e na implementação de três métodos que se valem de múltiplas antenas (múltiplos interferogramas) para resolver esses dois problemas, como se segue. O primeiro método efetua o método de desdobramento de fase pontual, através do desdobramento de fase iterativo dos interferogramas, seguido da fusão dos mesmos, usando máxima verossimilhança. O segundo método refina a estimação de fase absoluta através da estimação do deslocamento de fase usando múltiplas antenas não colineares. O método se baseia na minimização da distorção geométrica (ou erro relativo) induzida pelo processamento com a presença de deslocamentos de fase com valores diferentes do verdadeiro. Uma das vantagens do método é que ele dispensa a instalação de refletores de canto na região imageada. Por último, um algoritmo do tipo Monte Carlo foi desenvolvido para a determinação das posições relativas das antenas escravas em relação à antena mestre. O método utiliza refletores de canto, cujas posições em campo são conhecidas, para reduzir o erro quadrático médio / Abstract: Two important issues in SAR interferometry (InSAR) are absolute phase and baseline estimation. The precise knowledge of these parameters is essential for the production of digital elevation models with high accuracy. The absolute phase estimation can be done in two steps. The first step performs the unwrapping of the phase, which retrieves the 2? multiples of the phase. The second step estimates the phase offset caused by a combination of errors in the acquisition system and in SAR interferometry (InSAR) processing. The baseline estimation determines the relative position of the slave antenna with respect to the master antenna (reference antenna). The contributions of this thesis consist in the design and implementation of three methods that use multiple antennas to address the above issues. The first method performs the unwrapping of the phase in a pixel based fashion, by iteratively unfolding the phase corresponding to each interferograma, followed by maximum likelihood fusion of the unwrapped phases. The second method refines the absolute phase estimation of the first step by incorporating a phase offset estimation based on multiple, noncollinear, antennas. This is achieved by minimizing the geometrical distortion (relative error) in the reconstructed digital elevation model induced by erroneous phase offsets in the interferograms. One advantage of this method is that it does not require the deployment of corner reflector in the area to be imaged. Lastly, the third method deals with baselines estimation. A baseline is determined by the relative positions of the slave and master antennas. The estimation is performed with a greedy stochastic algorithm of Monte Carlo type which uses corner reflectors with precisely known positions. A new position for the slave antenna is accepted when the mean square error of the corner reflector positions is reduced / Doutorado / Telecomunicações e Telemática / Doutor em Engenharia Elétrica

No description available.

The Large Binocular Telescope Interferometer uses a near-infrared camera to measure the optical path length variations between the two AO-corrected apertures and provide high-angular resolution observations for all its science channels (1.5-13 microns). There is however a wavelength dependent component to the atmospheric turbulence, which can introduce optical path length errors when observing at a wavelength different from that of the fringe sensing camera. Water vapor in particular is highly dispersive and its effect must be taken into account for high-precision infrared interferometric observations as described previously for VLTI/MIDI or the Keck Interferometer Nuller. In this paper, we describe the new sensing approach that has been developed at the LBT to measure and monitor the optical path length fluctuations due to dry air and water vapor separately. After reviewing the current performance of the system for dry air seeing compensation, we present simultaneous H-, K-, and N-band observations that illustrate the feasibility of our feedforward approach to stabilize the path length fluctuations seen by the LBTI nuller.

Art and optics are inseparable. Though seemingly opposite disciplines, the combination of art and optics has significantly impacted both culture and science as they are now known. As history has run its course, in the sciences, arts, and their fruitful combinations, optical aberrations have proved to be a problematic hindrance to progress. In an effort to eradicate aberrations the simple beauty of these aberrational forms has been labeled as undesirable and discarded. Here, rather than approach aberrations as erroneous, these beautiful forms are elevated to be the photographic subject in a new body of work, On the Bright Side. Though many recording methods could be utilized, this work was composed on classic, medium-format, photographic film using white-light, Michelson interferometry. The resulting images are both a representation of the true light rays that interacted on the distorted mirror surfaces (data) and the artist’s compositional eye for what parts of the interferogram are chosen and displayed. A detailed description of the captivating interdisciplinary procedure is documented and presented alongside the final artwork, CCD digital reference images, and deformable mirror contour maps. This alluring marriage between the arts and sciences opens up a heretofore minimally explored aspect of the inextricable art-optics connection. It additionally provides a fascinating new conversation on the importance of light and optics in photographic composition.

As astronomers and astrophysicists seek to view ever-increasingly distant celestial objects, the desired angular resolution of telescopes is constantly being increased. Classical optics, however, has shown a proportional relationship between the size of an optical telescope and the possible angular resolution. Experience has also shown that prohibitive cost accompanies large optical systems. With these limitations on classical optical systems and with the drastic increase in computational power over the past decade, intensity correlation interferometry (ICI) has seen renewed interest since the 1950’s and 60’s when it was initially conceived by Hanbury Brown and Twiss. Intensity correlation interferometry has the advantage of less stringent equipment precision and less equipment cost when compared to most other forms of interferometry. ICI is thus attractive as a solution to the desire for high angular resolution imaging especially in space based imaging systems. Optical interferometry works by gathering information about the Fourier transform of the geometry of an optical source. An ICI system, however, can only detect the magnitude of the Fourier components. The phase of the Fourier components must be recovered through some computational means and typically some a priori knowledge of the optical source. This thesis gives the physics and mathematical basis of the intensity correlation interferometer. Since the ICI system cannot detect the phase of an optical source's Fourier transform, some known methods for recovering the phase information are discussed. The primary method of interest here is the error-reduction algorithm by Gerchberg-Saxton which was adapted by Fienup to phase retrieval. This algorithm works by using known qualities of the image as constraints; however, sometimes it can be difficult to know what these constraints are supposed to be. A method of adaptively discovering these constraints is presented, and its performance is evaluated in the presence of noise. Additionally, an algorithm is presented to adapt to the presence of noise in the Fourier modulus data. Finally, the effects of the initial condition of the error-reduction algorithm are shown and a method of mitigating its effect by averaging several independent solutions together is shown.

published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy