Spatial variation of soil moisture content under a sub-surface drip irrigated field was studied. Conventional statistics and geostatistical methods were used to analyze the relation between four soil variables: % sand, % silt, % clay, and soil moisture content. The soil moisture content was measured before, during, and after irrigation using tensiometers. The samples were collected from 63 sites on a 180 by 244 meters (4.45-hectare) cotton field. The pre- and post-irrigation soil moisture content shared the same spatial structure, differing only by the magnitude of their variances. After any irrigation the soil wetter points remained wetter and the drier points remained drier. It was found that the spatial patterns of soil moisture content appear to be stable over time. The ranges obtained from the variograms before and after an irrigation had the same magnitude of influence. The coefficient of uniformity obtained using the gravimetric method was 92.4 %, however, using tensiometers values ranged from 84.4 to 87.3%.

In the incineration of liquid hazardous wastes there exist "rogue" droplets (>300 μm diameter) which penetrate past the flame zone and burn as isolated droplets in the postflame gasses. Detailed knowledge of the droplet burnout points are essential to keeping the destruction removal efficiency in excess of the 99.99% required. The spread in trajectory endpoints of individual evaporating droplet streams injected into a turbulent combustor was investigated numerically. Results are in good agreement with the measurements. Correlation between the spread in the burnout points and initial droplet size, initial droplet velocity, interdroplet spacing, and droplet injection angle were investigated. The numerical investigation utilizes the novel One Dimensional Turbulence (ODT) {Kerstein (1999)} for the time developing fluid velocity and temperature fields with a new two phase flow model for predicting particle trajectories. The droplet heating/burning model used by Mulholland et al. (1991) is modified for application to this thesis.

Kleinauskas M. Research of static strenght and rigidity for wheel of bicycle: Master there is of mechanical engineer/ research advisor S.Rimovskis; Šiauliai University, Technology Faculty, Mechanical Engineering Department. – 2006. – 37p. In the countries of world bicycle is not only a widely used commodity, means of transport, but an index of mode of life. This work analyses a very important part of bicycle construction – a wheel. Strength and rigidity analysis are made using analytical and numerical solving methods. The main purposes of solving are elastic stress distribution in the wheel and the maximum value of the residual deflection. The condition and magnitude of load were estimated according to standard DIN 97100. Received results show if the wheel exploitation reliability is good ant its parameters meet the requirements of standards. The aim of the research: to prepare the methods of bicycle wheel strength and rigidity analysis for researches. Using the programme package ANSYS, to make wheel construction FEM model and perform strength and rigidity numerical solving, estimating of elastic plastic loading conditions.

This thesis describes the creation of a dynamics model of an autonomous underwater vehicle. Motion equations are integrated to obtain the position and velocity of the vehicle. External forces acting on the vehicle, such as hull and control plane hydrodynamic forces, are predicted for the full 360° angle of attack range. This enables the simulation of high angle of attack situations. An accurate through-body thruster model is also incorporated into the simulation. The vehicle model is validated using experimental turning diameters of the ARCS vehicle.

For decades the prime role of metallurgists has been to optimize material microstructure for performance by designing and applying appropriate thermo-mechanical processing steps. Until recently the study of the relationships between processing and microstructure has largely remained within the purview of experimental metallurgists because the mechanisms that contribute to the microstructural changes are very complex, and the changes occur either simultaneously or successively to varying degrees, depending on location within the material. The development of computational models for predicting the overall response of materials to such a complex microstructural changes is extremely difficult. However, recent advances in high-performance computing have led to considerable progress in addressing this challenge. This study addresses this question by focusing on the textural point of view which in this work is represented by the crystallographic texture (also called Orientation Distribution Function or ODF). The textural representation of the material is expanded in terms of spherical harmonics. Developing such approach is a crucial to advances in material-by-design. This model is based on a conservation principle in the orientation space. It links any desired final microstructure of a polycrystalline material to a given initial state. To investigate a typical processing example of deformation in tension, compression and rolling for isotropic copper, an FCC material, a microstructure is numerically simulated using a Taylor type model. Taylor models are known to correctly fit the deformation of cubic microstructures. A first goal is to determine the number of texture coefficients and their values for different expansions of the Fourier series. The second to use the texture coefficients in a processing path model to predict the microstructure evolution. The difference between the experimental and the predicted texture coefficients will be evaluated using the root mean square deviation for various expansions of the Fourier series. Also it is necessary to know how small a step size one needs to use in the numerical discretization of the deformation process. To increase accuracy we introduce Richardson extrapolation. This method allows us to increase the size of the discretization step and result in a small error. For hexagonal close-packed materials, the Taylor model is not applicable. Therefore to verify the processing path model for the example of commercially pure titanium, the texture evolution matrix is modeled using experimental data obtained for cold and warm rolling. The model appears to be of good accuracy. To examine how much of the possible microstructural material properties are achievable using typical deformation processes, the microstructural evolution is visualized within the microstructure hull. The results suggest that vast amounts of possible microstructural configurations are unexplored by those classical deformation methods. / A Dissertation submitted to the Department of Mechanical Engineering in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Summer Semester, 2006. / June 19, 2006. / Processing Path, Texture Evolution, Spherical Harmonics, Material by Design / Includes bibliographical references. / Hamid Garmestani, Professor Co-Directing Dissertation; Justin Schwartz, Professor Co-Directing Dissertation; Young Park, Outside Committee Member; Leon Van Dommelen, Committee Member.

<p>Bellows expansion joints are used in piping systems to absorb significant axial and/or transverse motions. Unfortunately, their flexibility also makes them susceptible to vibration. This thesis presents a detailed analysis of the transverse vibrations of single and double bellows expansion joints, including the effects of internal fluid.</p> <p>A differential equation of motion is developed which treats transverse bellows vibrations including the effects of fluid added mass, rotary inertia and internal pressure. The added mass is determined from potential flow theory and provided in the form of a mode dependent added mass coefficient. The equation of motion is solved for the first four transverse modes and comparison with experiments shows excellent agreement. The neglect of rotary inertia and the effect of convolution distortion on fluid added mass in the EJMA Standard makes the latter's predictions for natural frequency significantly higher than those measures, especially for transverse modes above the fundemental.</p> <p>The equation of motion is also solved approximately to provide an analytical expression for transverse natural frequncies. The results are presented in a form which makes hand calculations possible for the first four modes of single and double bellows expansion joints. Experiments in still fluid as well as flow-induced motion show excellent agreement with predicted frequncies.</p> / Thesis / Doctor of Philosophy (PhD)

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