The thesis presents a defocusing technique to extract bubble depth information. Typically, when a bubble is out of focus in an image, the bubble is ignored by applying a filter or thresholding. However, it is known that a bubble image becomes blurred as the bubble moves away from the focal plane. Then, this technique is applied to determine the bubble distance along the optical path based on the blurriness or intensity gradient information of the bubble. Using the image processing algorithm, images captured in three different experiments are analyzed to develop a correlation between the bubble distance and its intensity gradient. The suggested models to predict the bubble depth are also developed based on the measurement data and evaluated with the measured data. When the intensity gradient of the bubble is lower or when a bubble is located farther from the focal plane, the model can predict the distance more accurately. However, the models show larger absolute and relative error when the bubble is near the focal plane. To improve the prediction in that region, another model should be considered. Also, depth of field analysis is introduced in order to compare three experimental results with different imaging setups. The applicability of the approach is analyzed and evaluated. / Master of Science / Gas and liquid measurements of two-phase flow are very challenging, but it has become more important because of many industrial applications such as chemical, petroleum, and energy industries. Many two-phase flow measurement techniques have been developed and utilized for different flow conditions such as fiber optic probe, multi-sensor conductivity probe, wire-mesh sensor, as x-ray densitometry, particle image velocimetry (PIV), and optical imaging. With the development of the technology, the imaging technique can provide better spatial and temporal resolutions as well as image processing speed has improved greatly. In this study, the imaging and defocusing techniques are combined and used to extract bubble depth information. An image processing algorithm has been developed to process bubble images captured by high speed cameras. By measuring the blurriness or intensity gradient information of the bubble, the bubble distance along the optical path is determined. Based on the measurement data, mathematic models are developed to predict the bubble depth. In addition, depth of field analysis is suggested to compare three experimental results with different imaging setups. The applicability of the approach is analyzed and evaluated.

This dissertation is a philosophical contribution to the theories on trust and on risk communication. The importance of trust in risk communication has been argued for and empirically studied since the 80s. However, there is little agreement on the notion of trust and the precise function of trust. This thesis sets out to study both aspects from a philosophical point of view. The dissertation consists of five essays and an introduction. Essay I is a comment on risk perception theory and the psychometric model in particular. The essay argues that sometimes individuals take risks simply because they are in a vulnerable position and have no other choice. Four factors are identified as crucial in risks from vulnerability: poor outset conditions, lack of reasonable options, hope and liability to disinformation. Essay II addresses the democratic approach to risk communication and the ideal of risk communication as a dialogue between more or less equal stakeholders. The essay develops a typology of different risk communication practices and influence distributions and concludes that the form of risk communication most commonly referred to in the literature is of the most imbalanced kind where all three types of influence falls to the same party. Essay III argues that trust can be understood as comfortable defocusing. Trust as comfortable defocusing means that when a person trusts, he or she is comfortable with letting certain things be in the hands or in the control of the trusted other. Departing from this idea a definition of trust is proposed consisting of three elements: (i) the truster’s comfortable defocusing from the trusted person’s part of caring for X, based on a (ii) belief about the trusted person’s care for X, concerning (iii) something of concern to the truster. Essay IV explores the concept of trustworthiness and under which conditions trust can be betrayed in a morally justified way. It is argued that two aspects are essential for every reasonable notion of trustworthiness: reliability in terms of commitment to trust and predictability in terms of compliance with norms. In order to be untrustworthy in a morally justified way two major conditions need to be fulfilled: first, what is expected from the trustee needs to be either immoral or part of an ongoing immoral or unjust relationship between truster and trustee and, secondly, the trustee must not be in a position to explicitly reject trust. Essay V examines two of the most employed distinctions within the trust literature, that of trust/confidence and of trust/reliance. These distinctions are evaluated against a set of five criteria. It is argued that both these distinctions are employed to cover several distinguishing properties, thus adding to conceptual confusion. / QC 20100712

The general aim of this thesis was to investigate affective forecasting in the context of public transport. Paper I, Study 1 revealed that non-users of public transport were less satisfied with the services than users. It was hypothesised that non-users were biased in their satisfaction ratings, a claim that was subsequently investigated in Paper I, Study 2, where a field experiment revealed that car users suffer from an impact bias, due to being more satisfied with the services after a trial period than they predicted they would be. To address the question of whether a focusing illusion is the psychological mechanism responsible for this bias, two experiments containing critical incidents were conducted in Paper II. These experiments investigated whether car users exaggerate the impact that specific incidents have on their future satisfaction with public transport. A negative critical incident generated lower predicted satisfaction with public transport, both for car users with a stated intention to change their current travel mode (in Paper II, Study 1) and for car users with no stated intention to change their travel mode (in Paper II, Study 2), which support the hypothesis that the impact bias in car users’ predictions about future satisfaction with public transport is caused by a focusing illusion. Paper III showed that car users misremember their satisfaction with public transport as a result of their recollections of satisfaction with public transport being lower than their on-line experienced satisfaction. Additionally, the desire to repeat the public transport experience is explained only by remembered satisfaction, not by on-line experienced satisfaction. Paper IV investigated whether a defocusing technique would counteract the focusing illusion by introducing a broader context, thereby generating higher predicted satisfaction. A generic defocusing technique, conducted in Paper IV, Study 1, did not generate higher predicted satisfaction, whereas a self-relevant defocusing technique conducted in Paper IV, Study 2 generated higher predicted satisfaction with public transport. Additionally, it was found that car-use habit accounts for the level of predicted satisfaction regardless of defocusing; the stronger the car-use habit, the lower the predicted satisfaction. The conclusions from this thesis are that non-users of public transport rate the services lower than users do, and that car users become more satisfied when using the services than they predicted. These mispredictions are a result of over-focusing on a limited range of aspects in public transport (i.e., a focusing illusion). Car users’ desire to repeat the public transport experience is influenced by their inaccurate memories of the services and not by their actual experiences. However, defocusing techniques may help car users make more accurate predictions about future satisfaction with public transport; this could facilitate a mode switch from using the car to using public transport services more often. Switching to a more sustainable transport mode could be beneficial for the individual and for society.

Incomplete data, unknown source-receiver signatures and free-surface reflectivity represent challenges for a successful prediction and subsequent removal of multiples. In this paper, a new method will be represented that tackles these challenges by combining what we know about wavefield (de-)focussing, by weighted convolutions/correlations, and recently developed curvelet-based recovery by sparsity-promoting inversion (CRSI). With this combination, we are able to leverage recent insights from wave physics towards a nonlinear formulation for the multiple-prediction problem that works for incomplete data and without detailed knowledge on the surface effects.

The aim of this work is to design algorithm that will detect pupil from video. The theoretical knowledge necessary for proper pupil detection is also described in this master’s thesis. Detection is done on 24 videos that are converted to single images. The complete result the dependence of the pupil diameter on the used dioptre. The overall success rate of the algorithm is 88,13 %. The overall error is 11,87 %. For 17 out of 24 patients, it is confirmed that the greater the dioptre, the larger the pupil.

Fast deflection is one of the great advantages of an electron beam, making it possible to process a relatively large area at once and also to modify the distribution of the supplied energy. The dissertation deals with surface heat treatment with a focus on the effect of beam deflection on the process. Furthermore, the influence of processing speed and defocusing of the electron beam is studied. The principles of electron beam technology and the summary of surface heat treatment of various materials are presented in the literary part of the thesis. The experimental part is focused on the influence of process parameters on processing in the solid phase, carried out on steel 42CrMo4, and in in the liquid phase, carried out on alloy NiCrBSi. Especially changes in structure, hardness, shape of the processed area and wear resistance are evaluated on processed samples. The results are also evaluated from an energy perspective. Furthermore, an optimum combination of technological parameters is recommended for solid and liquid phase surface heat treatment.

Three-dimensional linear ray theory is used to investigate internal waves interacting with a Lamb-Chaplygin pancake vortex dipole. These interactions involve waves propagating in the same (co-propagating) and opposite (counter-propagating) horizontal directions as the dipole translation. Co-propagating internal waves in the vertical symmetry plane between the vortices of the dipole can approach critical levels where the wave energy is absorbed by the dipole or where the waves are overturned and possibly break. As wave breaking cannot be simulated with this linear model, changes in wave steepness are calculated to aid in estimating the onset of breaking. Counter-propagating internal waves in the vertical symmetry plane can experience horizontal and vertical reflections, including turning points similar to waves in two-dimensional steady shear. Wave capture is also a possible effect of either type of interaction, depending on initial wave properties and positioning relative to the vortex dipole. Away from the vertical symmetry plane, a spanwise converging (focusing) and diverging (defocusing) of wave energy is observed in co- and counter-propagating interactions as symmetric off-center rays interact with the dipole's individual vortices. Some off-center rays experience multiple horizontal refractions similar to wave trapping.

Abstract An optical lattice is a periodic array produced by the superposition of two or more counter-propagating laser beams which interfere and create a spatial periodic intensity pattern. An important difference between a solid state crystalline lattice and an optically induced lattice is that the latter have a longer coherence time which permits the observation of coherent phenomenon such as Bloch oscillations. Recently, an interesting effect has been reported in the literature, which is the analogue of Rabi oscillations in two level systems driven by an external optical field: an optical beam composed by pair of frequencies, resonants with the high symmetry points of the Brillouin zone, propagating through an optical lattice exhibits oscillations of the Fourier ways between the frequencies due to the coupling with the lattice. Therefore, in the optical case the field plays the role of the matter, while the lattice plays the role of the driving field which couples the frequencies. Based in this result, the objective of this paper is to investigate the influence of self-defocusing in the optical Rabi oscillation. We have shown, through numerical calculation of the wave nonlinear equation, that in the self-defocusing optical lattice, these oscillations go disappearingare. The result of the disappearance of the oscillations of Fourier can be understood considering that self-defocusing promotes an addition of phases in the ways that were resonant - kB and kB, in different way, form that the basic difference between kB and - kB will not be plus a vector of the reciprocal net, and as consequence the oscillations of optic Rabi disappear, therefore the coupling with the net requires this condition in the resonant frequencies. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Resumo Uma rede opticamente induzida é um arranjo periódico produzido pela superposição de dois ou mais feixes de laser que ao interferirem criam um padrão de intensidade periódico espacial. Uma importante diferença entre uma rede cristalina no estado sólido e uma rede produzida opticamente é que a última apresenta um tempo de coerência longo, permitindo a observação de fenômenos coerentes tal como as oscilações de Bloch. Recentemente, um efeito interessante análogo às oscilações de Rabi em um sistema atômico de dois níveis impulsionado por um campo externo, foi publicado na literatura: um feixe óptico composto de um par de freqüências, ressonantes com os pontos de alta simetria da zona de Brillouin, propagando - se através de uma rede óptica exibe oscilações dos modos de Fourier entre as freqüências adequadas para o acoplamento com a rede. Portanto, no caso óptico o campo representa a matéria, enquanto a rede representa a intensidade do campo aplicado que acopla as freqüências. Baseado neste resultado, o objetivo desta dissertação é investigar a influência da auto - desfocalização nas oscilações ópticas de Rabi. Demonstraremos, através de cálculos numéricos da equação de onda não linear, que em uma rede opticamente induzida na presença da auto - desfocalização, essas oscilações vão desaparecendo. O resultado do desaparecimento das oscilações de Fourier pode ser compreendidoconsiderando que a auto - desfocalização promove um adicionamento de fases nos modos que eram ressonantes -kB e kB, de maneira diferente, de forma que a diferença básica entre kB e -kB não será mais um vetor da rede recíproca, e como conseqüência as oscilações de Rabi óptica desaparecem, pois o acoplamento com a rede requer esta condição nas freqüências ressonantes.

The Terrestrial digital radio links are used for transmitting digital information between fixed stations on a line of sight of a radio path. Each digital radio link has many characteristics and parameters for transmission. We require technical parameters in the design of digital radio link such as data rates and capacities. In this design we should take into account most effects of the electromagnetic waves propagation, if we want to meet user technical requirements of the link and if that link may correctly transmit digital signals with minimum errors. Prediction methods for the design of terrestrial line of sight systems are still in progress. Some effects of electromagnetic waves propagation and methods of the digital radio link design depend on natural variability and climate. The goal of this diploma thesis is to investigate methods for the design of terrestrial line of sight links with taking into account of ITU recommendation. Make computer program which implement this investigate methods