This diploma thesis deals with the comparative analysis of the physiological, degenerative and postoperative state of the lumbar spine. The problem was solved by computational modeling using the finite element method. For this solution, it was necessary to create appropriate computational models. The spine physiological state was compared with cases of the lumbar spine with different levels of spondylolisthesis, cases of the lumbar spine with different sacral angles, and cases of lumbar spine with applied fixators. Based on the performed analyses, it was found that spine degenerative state has a great influence on the distribution of stress in the vertebral discs and the vertebra itself. Compared to the physiological state, with increasing level of the spondylolisthesis the stress in the vertebral discs increases, while the stress in the vertebral section decreases. Furthermore, the spondylolisthesis affects the force flow. The higher the level of the spondylolisthesis, the more the force flow is shifted onto the posterior articular ligaments. The best results in terms of the spine physiological state were achieved with the applied fixator model.

The thesis describes the relaxation properties of bituminous binders determined in dynamic shear rheometer (DSR). Paving bitumen, polymer modified bitumen (PMB) and crumb rubber modified bitumen (CRmB) were chosen for comparison. In order to describe the effects of ageing on asphalt binders relaxation properties, the laboratory simulation of ageing using RTFOT and 3xRTFOT method was performed. For each binder were simultaneously conducted tests of needle penetration, softening point and elastic recovery. Selected bitumens were used for the production of asphalt mixtures. The low-temperature properties tests (TSRST) were performed for these mixtures, when the results were compared to the relaxation properties of binders determined in the DSR.

The thesis deals the assessment of the resistance of the existing boulder chute in the river Lomná. At km 1,9 Boulder chute is located in the village Jablunkov. Surface resistance of boulder chute is assessed newly on the basis of non-dimensional shear stress for particle on arbitrarily sloped bed. The calculation of 2D flow was computed by HEC-RAS. On the assessment of resistance was proposed reconstruction of boulder chute.

The aim of this master thesis is to explore the influence of frictional forces to the stress and strain on the straight crack tip loaded in shear modes. The first section summarizes the most important things from the field of fracture mechanics. Especially theoretical knowledge about fracture parameters (stress intensity factor, J – integral) and their determination in computational environment ANSYS Workbench. The second part deals with computational modeling. At the beginning, is created the model of material, the model of geometry, the model of loads, etc. Then it is possible to solve the direct problem outlined in the introduction. A result of this thesis is the assessment of how the friction influences the fracture parameters in shear modes II and III.

Flow rate measurements are a common topic for process monitoring in chemical engineering and food industry. To achieve the requested low uncertainties of 0:1% for flow rate measurements, a precise measurement of the shear layers of such flows is necessary. The Laser Doppler Velocimeter (LDV) is an established method for measuring local flow velocities. For exact estimation of the flow rate, the flow profile in the shear layer is of importance. For standard LDV the axial resolution and therefore the number of measurement points in the shear layer is defined by the length of the measurement volume. A decrease of this length is accompanied by a larger fringe distance variation along the measurement axis which results in a rise of the measurement uncertainty for the flow velocity (uncertainty relation between spatial resolution and velocity uncertainty). As a unique advantage, the laser Doppler profile sensor (LDV-PS) overcomes this problem by using two fan-like fringe systems to obtain the position of the measured particles along the measurement axis and therefore achieve a high spatial resolution while it still offers a low velocity uncertainty. With this technique, the flow rate can be estimated with one order of magnitude lower uncertainty, down to 0:05% statistical uncertainty.1 And flow profiles especially in film flows can be measured more accurately. The problem for this technique is, in contrast to laboratory setups where the system is quite stable, that for industrial applications the sensor needs a reliable and robust traceability to the SI units, meter and second. Small deviations in the calibration can, because of the highly position depending calibration function, cause large systematic errors in the measurement result. Therefore, a simple, stable and accurate tool is needed, that can easily be used in industrial surroundings to check or recalibrate the sensor. In this work, different calibration methods are presented and their in uences to the measurement uncertainty budget of the sensor is discussed. Finally, generated measurement results for the film flow of an impinging jet cleaning experiment are presented.

This diploma thesis investigates the design of concrete structures reinforced with non-metallic FRP reinforcement with a focus on solving the bearing capacity in extrusion. The work is divided into a theoretical and a practical part. The theoretical part begins with an introduction to FRP reinforcement and a description of shear stress. The following is an introduction to current approaches dealing with this issue. In the practical part, in connection with these regulations, parametric studies are developed to compare the influence of individual input parameters and selected regulations. The last part is dedicated to the design and nonlinear analysis performed in the ATENA software.

No description available.

多様化する樹脂材料の射出成形において，目的に応じた溶融状態を得るための高度な可塑化技術が求められている．本研究では，流動シミュレーションを用いて可塑化現象を定量化し，所望の溶融状態に対する影響因子を明らかにすることでスクリュ形状を最適化し，実験検証により検討の妥当性を確認した．また，スクリュ形状を3Dプリンタによりプロトタイピングし，疑似流体を用いた可視化モデル実験を提案し，新規スクリュの開発手法としての有効性を示した． / In injection molding of diversified resins, it has been required advancement of plasticizing technology in order to realize a melting condition according to purpose. This study investigated quantifying phenomena by flow simulation, and optimizing the screw design by clarifying the influence factors for the desired melting condition. The effects of optimized screw were confirmed the validity of results by experimental validations. Also, models experiments of visualizing test that utilized simulated fluid and prototyped screw by 3D printer were proposed, there were indicated efficacy for the development approach of new screw design. / 博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University

<div> <p> Aircraft engines require lightweight efficient thermal management devices to improve engine performance at high pressure ratios. Acoustic streaming can provide a viable, lightweight solution to improve the heat exchanger capacity with a reduced drag penalty within engine heat exchangers. This project develops a test section that will experimentally characterize the effect of acoustic streaming on the unsteady heat flux and shear stress within a narrow channel. This is accomplished by careful selection of measurement techniques to monitor the steady and unsteady properties of the flow and iteratively designing the test section with CFD support to converge to an optimal test model. Using CFD support to revise each iteration reduces the experimental cost of developing an effective geometry. </p> <p> Pressure taps and K-type thermocouples are used to monitor the total inlet pressure and temperature as well as the wall surface pressure and temperature. Optical shear stress sensors are selected to monitor the unsteady wall shear stress. A thin film sensor array is designed for high frequency wall temperature measurements which serve the boundary condition for a 1-D heat flux analysis to determine the unsteady heat flux through the wall. The test model consists of two hollow Teflon airfoils that create a narrow channel within a larger flow area. The airfoils create three flow paths within the wind tunnel test section and the area ratio between the measured flow and the bypass flow controls the Mach number of within the measured flow channel. The acoustic waves drive acoustic streaming and are generated by a Rossiter Cavity with L/D =2 which produces pressure oscillations with dominant frequency of 8 kHz in a Mach 0.8 flow. </p> <p> The test geometry successfully achieves <a>Mach 0.8 flow and the 8 kHz signal </a><a href="https://purdue0-my.sharepoint.com/personal/mbutzen_purdue_edu/Documents/MS Thesis/Thesis Living Document.docx#_msocom_1">[BMJW1]</a> from the Rossiter cavity. The successful commissioning sets the stage for future experiments to determine the potential of acoustic streaming as a low weight modification to improve compact heat exchangers. </p> </div> <div><div><div><br> </div> </div> </div>

In this thesis I investigate characteristics of turbulent flow in a channel where one of the walls has riblets, superhydrophobic microribs, or a hybrid surface with traditional riblets built on a superhydrophobic microrib surface. PIV measurements are used to find the velocity profile, the turbulent statistics, and shear stress profile in the rectangular channel with one wall having a structured test surface. Both riblets and superhydrophobic surfaces can each provide a reduction in the wall shear stress in a turbulent channel flow. Characterizing the features of the flow using particle image velocimetry (PIV) is the focus of this research. Superhydrophobicity results from the combination of a hydrophobic coating applied to a surface with microrib structures, resulting in a very low surface energy, such that the fluid does not penetrate in between the structures. The micro-rib structures are aligned in the streamwise flow direction. The riblets are larger than the micro-rib structure by an order of magnitude and protrude into the flow. All the test surfaces were produced on silicon wafers using photolithographic techniques. Pressure in the channel is maintained below the Laplace pressure for all testing, creating sustainable air pockets between the microribs. Velocity profiles, turbulent statistics, shear stress profiles, and friction factors are presented. Measurements were acquired for Reynolds numbers ranging from 4.5x10^3 to 2.0x10^4. Modest drag reductions were observed for the riblet surfaces. Substantial drag increase occurred over the superhydrophobic surfaces. The hybrid surfaces showed the greatest drag reduction. Turbulence production was strongly reduced during riblet and hybrid tests.