Made available in DSpace on 2014-10-09T12:48:30Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:48Z (GMT). No. of bitstreams: 1 09062.pdf: 5495950 bytes, checksum: 05fcc5eac43b40ff1c16ad82e5319158 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

During the economic crisis in the years 2008 - 2009, the management of the company TRW Dačice laid the requirement to increase efficiency and profitability of the production of radius rods. Master thesis deals with the analysis and a proposal of costs-saving actions.

The structure of turbulence in the subchannels of a large-scale 60 degree section of a CANDU 37-rod bundle was studied at Reynolds numbers equal to 50,000, 100,000 and 130,000. Measurements were conducted at roughly 33.81 rod diameters from the inlet of the rod bundle using single-point, two-component hot-wire anemometry. Analysis of the axial velocity signal indicated a weak effect of Reynolds number on the axial velocity distribution and a bulging of axial velocity contours toward the narrow gaps. The normalised normal Reynolds stresses and the normalised turbulent kinetic energy were found to decrease as the Reynolds number increased. The radial Reynolds shear stress varied linearly with radial distance from the rod, crossing zero at the location of local maximum of the axial velocity. This stress was symmetric about the central rod whereas the azimuthal Reynolds shear stress was anti-symmetric. The Reynolds number effect was weak but measurable on the integral length scales of the axial and radial velocity fluctuations but negligible on the integral length scale of the azimuthal velocity fluctuations, especially in the gap regions. The Taylor and Kolmogorov microscales increased from the wall toward the centre of the subchannel and decreased as the Reynolds number increased. The wall shear stress stress distribution around the central rod indicated no effect of Reynolds number, when normalized by the corresponding average. The wall shear stress reached local minima at rod-wall and rod-rod gaps and local maxima in the open flow regions. Vortex streets were generated within the subchannels very close to the inlet of the rod bundle. The convection speed and frequency of the vortex street were found to increase proportionately to Reynolds number, whereas the vortex spacing was not affected by the Reynolds number.

Rod bundle is a typical constitutive element of a very wide range of nuclear reactor designs. This thesis describes the investigation of such geometry with wall-resolved Large Eddy Simulation (LES). In order to alleviate the mesh constraint, imposed by the near wall resolution, the usage of embedded refinements and polyhedral meshes is analysed firstly with a inviscid laminar case (Taylor Green vortices) and secondly with a fully turbulent case (channel flow only with embedded refinement). The inviscid test case shows that the addition of embedded refinements decreases the conservation properties of the code. Indeed the accuracy decreases from second order in a structured conformal mesh, to something in between first and second order depending on the quality of the unstructured mesh. Better results are obtained when the interface between refined and coarse areas presents a more regular and structured pattern, reducing the generation of skewed and stretched cells. The channel flow simulation shows that the Reynolds stresses, of some embedded refined meshes, are affected by spurious oscillations. Surprisingly this effect is present in the unstructured meshes with the best orthogonal properties. Indeed analysis of Reynolds stress budgets shows that terms, where the gradient in the wall normal direction is dominant, have a largely oscillatory behaviour. The cause of the problem is attributed to the convective term and in particular in the method used for the gradient reconstruction. As a consequence of these contradictory signs between the inviscid and the fully turbulent cases, the rod bundle test case is analysed using a conventional body fitted multiblock mesh. Two different Reynolds numbers are investigated reporting Reynolds stresses and budgets. The flow is characterised by an energetic and almost periodic azimuthal flow pulsation in the gap region between adjacent sub-channels, which makes turbulent quantities largely different from those in plane channel and pipes and enhances mixing. Experiments found that a constant Strouhal number, with the variation of the Reynolds number, characterises the phenomenon. The frequency analysis finds that present simulations are distinguished by three dominant frequencies, the first in agreement with the experimental value and two higher ones, which might be due to the correlation of the azimuthal velocity in the streamwise direction. Several passive temperature fields are added at the simulations in order to study the effects of the variation of the Prandtl number and the change in boundary conditions (Neumann and Dirichlet). A simplified case where an imbalance of the scalar between adjacent sub-channels is also investigated in order to evaluate the variation of the heat fluxes with respect to the homogeneous case. An alternative solution, to reduce the mesh constraint imposed by the wall, is to hybridize LES with RANS. The main achievement of this work is to integrate the heat transfer modelling to the already existing model for the dynamic part. Further investigations of the blending function, used to merge the two velocity fields, are carried out in conjunction with a study of the model dependency on the mesh resolution. The validation is performed on a fully developed channel flow at different Reynolds numbers and with constant wall heat flux. On coarse meshes the model shows an improvement of the results for both thermal and hydraulic parts with respect to a standard LES. On refined meshes, suitable for wall-resolved LES, the model suffers from a problem of double counting of modelled Reynolds stresses and heat fluxes because the RANS contribution does not naturally disappear as the mesh resolution increases.

The aim of my thesis is to create a procedure for the calculation of con rod stress in MBS Software. The thesis contains several parts, i.e. a short research of contemporary con rods, con rod modelling with the use of Pro/E, methodics of the finite-element con rod model preparation and model analysis in ANSYS Software, creating of virtual combustion engine template with flexible con rod and carrying out a strain hardening analysis in ADAM/Engine software. The theme of my thesis is quite demanding in the combination and the use of several computer software programmes. The thesis offers a survey of possibilities, procedures and methodics of con rod stress solutions that help to clarify the matter.

Submitted diploma thesis deals with laboratory diagnostics of filamentous micromycetes (moulds) genus Fusarium in the laboratories of medical mycology. In the first part of the diploma thesis is dedicated space for general familiarization with filamentous microscopic fungi. Next separate chapter describes the genus Fusarium, especially in relation to human medicine. The final part of the diploma thesis summarizes current possibilities of laboratory diagnostics of filamentous micromycetes, focusing on the genus Fusarium. Invasive infections caused by filamentous fungi are increasingly common complication, especially in immunocompromised patients. In most cases they affect the patients with hematologic malignity and patients after hematopoietic stem cell transplantation or solid organ transplantation. The most common etiological agent of such infections is unambiguously the Aspergillus genus. However, in recent years, increasingly cases of infections due to less common filamentous fungi, including Fusarium spp. are described. Invasion fungal infections are associated with very high mortality. The basic requirement thus becomes the speed and accuracy of diagnosis. The most important methods for the laboratory diagnostics of invasive infections caused by filamentous fungi are conventional methods -...

4. Abstrakt Liechtenstein patron churches in south Moravia in the second half of 19th century This dissertation is concerned with the theme of Lichtensteiners supported churches,which was newly built or radicaly rebuilt in Moravia during the second half of 19th century. The dissertation asks the questions why these buildings were built and under what conditions. Asks How was the construction secured and who were the architects who designed these buildings. Whether on resulting style form participated only patron or projected also ideas of municipalities,clergymen and parishioners. At the same time is this dissertation devoted to a brief genealogy of the Lichtensteins mainly the personality of John II. of Lichtenstein. It maps all of the patronage churches of Lichtensteins on Moravia. Last but not least deals with competences and extent of activity of the courtyard office and of course with activity of courtyard building office.

Yes / Purpose: To demonstrate that silent substitution stimuli can be used to generate electroretinograms (ERGs) that effectively isolate rod photoreceptor function in humans without the need for dark adaptation, and that this approach constitutes a viable alternative to current clinical standard testing protocols. Methods: Rod-isolating and non-isolating sinusoidal flicker stimuli were generated on a 4 primary light-emitting diode (LED) Ganzfeld stimulator to elicit ERGs from participants with normal and compromised rod function who had not undergone dark-adaptation. Responses were subjected to Fourier analysis, and the amplitude and phase of the fundamental were used to examine temporal frequency and retinal illuminance response characteristics. Results: Electroretinograms elicited by rod-isolating silent substitution stimuli exhibit low-pass temporal frequency response characteristics with an upper response limit of 30 Hz. Responses are optimal between 5 and 8 Hz and between 10 and 100 photopic trolands (Td). There is a significant correlation between the response amplitudes obtained with the silent substitution method and current standard clinical protocols. Analysis of signal-to-noise ratios reveals significant differences between subjects with normal and compromised rod function. Conclusions: Silent substitution provides an effective method for the isolation of human rod photoreceptor function in subjects with normal as well as compromised rod function when stimuli are used within appropriate parameter ranges. Translational Relevance: This method of generating rod-mediated ERGs can be achieved without time-consuming periods of dark adaptation, provides improved isolation of rod- from cone-based activity, and will lead to the development of faster clinical electrophysiologic testing protocols with improved selectivity.

Page iii was not included in the thesis. / Abstract Not Provided. / Thesis / Master of Engineering (MEngr)

In this dissertation, experimental data was used to investigate the influence of a nearby mast structure on the striking distance to a lightning rod. The results of this research helped identify and understand the impact of different factors such as stroke polarity, lightning rod height, striking distance to the ground, lateral distance from the lightning stroke to an adjacent mast, and height of the adjacent mast on the striking distance of a lightning rod. Moreover, a system identification methodology was employed for the development and validation of striking distance models from experimental work performed at the Mississippi State University High Voltage Laboratory. Striking distance models were obtained to represent the striking distance to the ground, striking distance to an isolated lightning rod, and striking distance to a lightning rod in the presence of an adjacent mast. In the case of the striking distance to the ground the system identification approach was used for the extraction of the parameters of the black-box model proposed. From the results the relationship between the striking distance to ground and the leader voltage were obtained for both polarities of the lightning stroke. The system identification approach was then expanded to obtain the models for the striking distance to the lightning rod. The system identification approach was used to evaluate different mathematical models based on the ones found in the literature. The models were trained on experimental data, their quality evaluated, and the best model was selected for both positive and negative polarity. Furthermore, the model for negative polarity was evaluated against data from real lightning conditions in order to corroborate the model extrapolation capability. Building on the success obtained on the cases of the striking distance to the ground and to an isolated lightning rod the focus was turned to expanding the models to incorporate the influence of an adjacent mast. Models for positive and negative polarity were obtained and the quality of the equations was evaluated.