In translational medicine, complementary functional and morphological imaging techniques are used extensively to observe physiological processes in vivo and to assess structural changes as a result of disease progression. The combination of magnetic resonance imaging (MRI) and positron emission tomography (PET) provides excellent soft tissue contrast from MRI with exceptional sensitivity and specificity from PET. This thesis explores the use of sequentially acquired PET and MR images to improve the quantification of small animal PET data. The primary focus was to improve image-based estimates of the arterial input function (AIF), which defines the amount of PET tracer within blood plasma over time. The AIF is required to produce physiological parameters quantifying key processes such as metabolism or perfusion from dynamic PET images. The gold standard for AIF measurement, however, requires serial blood sampling over the course of a PET scan, which is invasive in rat studies but prohibitive in mice due to small total blood volumes. To address this issue, the geometric transfer matrix (GTM) and recovery coefficient (RC) techniques were applied using anatomical MR images to enable the extraction of partial volume corrected image based AIFs from mouse PET images. A non-invasive AIF extraction method was also developed for rats, beginning with the optimization of an automated voxel selection algorithm to assist in extracting MR contrast agent signal time courses from dynamic susceptibility contrast (DSC) MRI data. This procedure was then combined with dynamic contrast enhanced (DCE) MRI to track a combined injection of Gadolinium-based contrast agent and PET tracer through the rat brain. By comparison with gold standard tracer blood sample data, it was found that normalized MRI-based AIFs could be successfully converted into PET tracer AIFs in the first pass phase when fitted with gamma variate functions. Finally, a MR image segmentation method used to provide PET attenuation correction in mice was validated using the Cambridge split magnet PET/MR scanner?s transmission scanning capabilities. This work recommends that contributions from MR hardware in the PET field of view must be accounted forto gain accurate estimates of tracer uptake and standard uptake values (SUVs). This thesis concludes that small animal MR data taken in the same imaging session can provide non-invasive methods to improve PET image quantification, giving added value to combined PET/MR studies over those conducted using PET alone.

L'objectif de cette thèse est de proposer et d'étudier une méthode de segmentation qui soit adaptée à l'imagerie échographique ultrasonore (US) et qui tienne compte de certaines contraintes rencontrées en milieu clinique. De ce fait, cette méthode se doit d'être robuste au bruit de speckle et à l'atténuation des ondes US dans le milieu, mais aussi rapide et ne nécessiter que peu, voire aucun paramètre à régler par l'opérateur. Dans ce cadre, les solutions fondées sur des contours actifs fondés sur la Minimisation de la Complexité Stochastique ont été étudiées. L'impact de différentes modélisations du speckle sur les résultats de ces techniques de segmentation a été caractérisé. Il a été montré qu'il est important de prendre en compte les variations de l'intensité moyenne du speckle induites par l'atténuation dans chaque région de l'image, à la fois pour la segmentation et pour l'analyse des propriétés du speckle. De plus, une stratégie hiérarchique de segmentation a été développée. Celle-ci permet notamment d'accroître la qualité des segmentations et de diminuer les temps de calcul.Les algorithmes de segmentation considérés étaient initialement conçus pour des formes polygonales peu adaptées à celles rencontrées dans le cadre d'applications médicales. Nous avons donc développé un nouveau modèle de contour fondé sur la théorie de l'information qui permet toujours une mise en oeuvre rapide des algorithmes et ne dépend d'aucun paramètre à régler par l'utilisateur. Testé sur des images synthétiques et réelles de fantômes échographiques, ce nouveau modèle permet de mieux décrire les formes régulières et arrondies des objets rencontrés en imagerie échographique. / The purpose of this PhD thesis is to propose and study a segmentation method adapted to echographic ultrasound imaging that could be clinically operational (i.e. fast and parameter-free) and robust to both the speckle noise and the attenuation of the ultrasonic signal in the medium. The solutions we studied rely on statistical active contour methods that are based on the Minimization of the Stochastic Complexity (MSC). The impact on the segmentation results of several speckle noise models that still lead to fast segmentation algorithms has been characterized. A key feature of these models, that appears to be crucial for both the segmentation and the speckle characterization, is the ability to take into account the spatial variation of the average intensity induced by the attenuation of the signal in the medium. In addition, we proposed a hierarchical optimization strategy that improves segmentation results and decreases the computation time.Finally, a novel contour model that is adapted to smooth boundaries that are met in medical imaging is also proposed for the considered MSC segmentation algorithms. The construction of this contour model relies on Information Theory concepts. It still allows one to get low computation times and does not contain any tuning parameter. Evaluations performed on synthetic images and real echographic phantom images indicate that this contour model provides better segmentation results for smooth inclusions that usually compose the echographic images.

Thesis deals with the analysis of the sliding contact in the ring mill. It focuses on the assessment of the effect of the current load on the sliding contact, the assessment of the signal transmission quality from the static to the rotara part of the ring contact slide contact.

The goal of this master’s thesis is creating a model of the attenuation of the fluid temperature fluctuations using methods described in the thesis. PCM is used to attenuation of fluctuations. This thesis is example of utilization PCM in technical practice. Numerical calculation of PCM phase change uses the method of effective heat capacity and enthalpy method. A part of this thesis also forms a theoretical basis for heat transfer described by differential equations. The final part of the thesis is dedicated to the optimization of the model and the description of the optimization methods.

The diploma thesis describes the elaboration of a program for the simulation of an optical transmission path. The work introduces the basic parameters of optical transmission, such as attenuation, dispersion and bandwidth. Furthermore, the techniques of line code and error detection are described in the work, especially a cyclic redundancy sum. The key parameter of this thesis is dispersion of the optical signal. The work includes the characteristics of the eye diagram and its analysis. The resulting program can also be used to measure the real transmission route and its parameters.

This Master’s thesis analizes technologies suitable for metropolitan area networks. In this thesis there are mentioned technologies used for wireless transfer with speeds above 1 Gbps. There are described basic features and parameters of microwave radio relay links in 70/80GHz range and free space optic links. These technologies are compared with classic optical networks. Practical part of thesis was focused on development of application which calculates signal attenuation caused by the passage of the atmosphere for both technologies. Results gained from this application are mentioned in this Master’s thesis.

The aim of this thesis is to study the methods of a free space optical link design and its application in the communication technologies. The thesis describes possible intrusive influences on the transmitted optical signal, which are the signal noise, atmospheric attenuation and atmospheric turbulences. The thesis is particulary focused on the influence of the atmospheric turbulences and atmospheric attenuation on the optical beam.

The thesis analyzes the optical laser range finders in real propagation environments. Itdescribes the various parts of optical laser range finders their properties and principles in relation to their performance balance. The paper presents the basic optical properties of lenses used in the transmitter and receiver. A separate chapter is devoted to the transit time method and factors influencing the measurement. The proportional directional reflectance analysisis a part of the thesis. In conclusion, the thesis contains the practical laboratory measurements of the relative directional reflectance of different materials and colors, and verification of the power level diagram.

This thesis is focused on a detailed analysis of the mechanisms of electromagnetic wave propagation in anechoic chambers. The analysis takes into account the influence of the measurement distance, setup of anechoic chamber and other parameters. Furthermore, the work deals with a validation of both types of anechoic chambers and examines the impact of selected parameters on the measurement results. Based on the theoretical analysis and practical measurement, the comparation between semi and fully anechoic chamber, or a three and ten meter measuring distance was made. This thesis also contains a detailed analysis of sources of the uncertainty.

The objective of this diploma thesis is a dynamic analysis of a cable-stayed walkway. The RFEM structural analysis software is used for the calculation. Design principles of the structure are explained and analysis of the construction phases is then performed. The eigenmodes of the structure are calculated for various material combinations. The thesis examines the effects of moving loads and earthquake effects using several different methods. A comparison of the various loading effects on the structure and also the calculation methods is presented at the conclusion.