Cross frames and diaphragms are essential to the stability of straight steel girder bridge systems as they help to resist lateral torsional buckling during construction and horizontal loading conditions. In skewed bridge systems, cross frames are often oriented parallel to the supports and hence, at an angle to the girder. To facilitate construction fit-up, plates, bent to match the skew angle, form the cross frame to stiffener connection. While the bent plate connection is a simple solution, it could introduce undesirable flexibility into the system, potentially compromising the effective brace stiffness. A proposed detail utilizing half pipe stiffeners may provide enhanced structural performance, while possibly reducing overall fabrication costs. Field and laboratory tests to determine the stiffness of both connection types are presented in the thesis. / text

Lateral bracing systems consisting of cross frames and their connections play a significant role in the elastic buckling strength of steel girder bridges. By providing lateral and torsional stability, they prevent lateral torsional buckling of the girder during bridge construction prior to the concrete bridge deck curing. To perform this function, the bracing system must possess adequate strength and stiffness. And since each component of the bracing system acts in series, the overall stiffness of the system is less than the least stiff component. In skewed bridges, cross frames at the ends of the girders are installed parallel to the bridge skew angle, and their connection to the girder requires that the cross frames be at an angle that prohibits welding a stiffener from the cross frame directly to the girder web. To make this connection, many states use a bent plate to span the angle between the web stiffener and cross frame. While this bent plate connection is now being widely used, it has never been rationally designed to account for its strength or stiffness in the bracing system. Results from field studies show that the bent plate connection may be limiting the cross frame stiffness thereby hampering its ability to provide stability to the girder during construction. The result is significant girder end rotations. The purpose of this research is to classify the impact of the bent plate connection on the end cross frame stiffness in skewed straight steel girder bridges and propose methods to improve the end cross frame’s structural efficiency. This research uses laboratory testing, finite element modeling, and parametric studies to recommend design guidance and construction practices related to the end cross frames of skewed steel girder bridges. In addition to recommending methods to stiffen the existing bent plate connection, an alternative pipe stiffener connection is evaluated. The pipe stiffener not only offers the possibility of a stiffer connection, but can also provide warping restraint to the end of the girder which may significantly increase the girder elastic buckling capacity. / text

This thesis presents an analytical and experimental investigation into the capillary wicking limitation of an array of pillars. Commercial and nanopillar wicks are examined experimentally to assess the effects of micro and nanoscale capillary forces. By exerting a progressively higher heat flux on the wick, a maximum achievable mass flow was observed at the capillary limit. Through the balance of capillary and viscous forces, an ab initio analytical model is also presented to support the experimental data. Comparison of the capillary limit predicted by the analytical model and actual limit observed in experimental results are presented for three baseline wicks and two nanowicks. / text

This is an applied ethnographic study of Southern Paiute cultural resources and how these are related to the natural ecosystems that surround and incorporate Zion National Park in southern Utah and Pipe Spring National Monument in northern Arizona. Southern Paiute people perceive Zion National Park and Pipe Spring National Monument as places whose significance derives from larger cultural and ecological landscapes. Southern Paiute people view both parks as being parts of riverine ecosystems. Zion National Park is a place along the Virgin River, and Pipe Spring National Monument part of the greater Kanab Creek Hydrological System. The current boundaries of both parks are largely irrelevant for understanding the lives of birds that fly along the river, of deer who seasonally migrate up and down the river, and of fish who swim in the river. Paiute people, whose ancestors lived along these riverine ecosystems for a thousand years or more, recognize that the plants they gathered, the animals they hunted, and the lives they lived are unrelated to the current boundaries of these two parks. As a result, the National Park Service and the Southern Paiutes arrived at the same conclusion: that is, to understand the cultural and natural significance of these parks requires knowledge of their relationships with other places. Thus it is both administratively and culturally appropriate for this applied ethnographic study to follow an ecosystem approach. This study was unique in two major ways. Unlike many other American Indian cultural resources studies conducted within National Parks at this period of time, this study moved beyond the formal boundaries of these NPS units in an effort to understand them as components of a broader natural ecosystem. As such, this study built upon the scientific and social framework for ecologically based stewardship of Federal lands and waters. This report provides both the ethnographic information relating to Pipe Spring National Monument and Zion National Park. This information was then incorporated in the parks’ resource management plans

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This thesis presents a method for optimizing cable configuration inside a large magnetic cylindrical steel casing, from the total ampacity point of view. The method is comprised of two main parts, namely: 1) analytically calculating the electromagnetic losses in the steel casing and sheathed cables, for an arbitrary cables configuration, and 2) implementing an algorithm for determining the optimal cables configuration to obtain the best total ampacity. The first part involves approximating the eddy current and hysteresis losses in the casing and cables. The calculation is based on the theory of images, which this thesis expands to apply to casings having both high magnetic permeability and high electric conductivity at the same time. The method of images, in combination with approximating the cable conductors and sheaths as multiple physical filaments, is used to compute the final current distributions in the cables and pipe and thus the associated losses. The accuracy of this computation is assessed against numerical solutions obtained using the Maxwell finite element program by Ansoft. Next, the optimal cable configuration is determined by applying a proposed two-level optimization algorithm. At the outer level, a combinatorial optimization based on a genetic algorithm explores the different possible configurations. The performance of every configuration is evaluated according to its total ampacity, which is calculated using a convex optimization algorithm. The convex optimization algorithm, which forms the inner level of the overall optimization procedure, is based on the barrier method. This proposed optimization procedure is tested for a duct bank installation containing twelve cables and fifteen ducts, comprising two circuits and two cables per phase, and compared with a brute force method of considering all possible configurations. The optimization process is also applied to an installation consisting of a single circuit inside a large magnetic steel casing.

The goal of this thesis is to develop more effective quantitative procedures to evaluate the stability of deteriorated metal culverts and a better understanding of the deteriorated culverts' behaviour through non-destructive testing, full scale experiments and numerical analyses. First, three design cases were examined using numerical analysis to study the effects of corrosion, burial depth and staged construction on the capacity of deteriorated steel culverts. Then, a method to measure the remaining wall thickness of two 1.8 m diameter corroded metal culverts using ultrasonic device was developed. Both culverts were then buried in the test pit at Queen's University and tested under nominal and working vehicle loads at 0.9m cover and 0.6m cover. The more heavily corroded structure (CSP1) was tested up to its ultimate limit state, inducing local bending across the crown, as well as local buckling of the remnants of the corrugated steel wall between perforations at the haunches. The results suggest that the single axle pads interact to influence the culvert's behaviour despite the shallow cover used in these experiments. CSP1 was able to carry the working load and did not fail until reaching 340 kN, which was equal to 90% of the fully factored load. The experiment suggests that less deteriorated metal culverts (as compared to CSP1) may have the required capacity. Two finite element packages, CANDE and ABAQUS, were used to perform the numerical investigation and the AASHTO and CHBDC approaches were then used to calculate the thrust force in the culverts. Although the numerical analysis produced conservative values for the thrust forces, it failed to capture the non-linear behaviour of both specimens in the experiments. Both the AASHTO and the CHBDC approaches produced unconservative thrust forces compared to experimental results while numerical analysis using Moore's spreading factor produced the most conservative results in terms of thrust. The analysis suggests that CANDE could be used to predict thrust forces in less deteriorated metal culverts. A procedure to assess the stability of deteriorated corrugated metal culverts based on quantitative data was developed using the numerical analysis and experimental results. / Thesis (Master, Civil Engineering) -- Queen's University, 2013-01-30 12:56:17.945

For the qualification and validation of two-phase CFD-models for medium and large-scale industrial applications dedicated experiments providing data with high temporal and spatial resolution are required. Fluid dynamic parameter like gas volume fraction, bubble size distribution, velocity or turbulent kinetic energy should be measured locally. Considering the fact, that the used measurement techniques should not affect the flow characteristics, radiation based tomographic methods are the favourite candidate for such measurements. Here the recently developed ultrafast X-ray tomography, is applied to measure the local and temporal gas volume fraction distribution in a vertical pipe. To obtain the required frame rate a rotating X-ray source by a massless electron beam and a static detector ring are used. Experiments on a vertical pipe are well suited for development and validation of closure models for two-phase flows. While vertical pipe flows are axially symmetrically, the boundary conditions are well defined. The evolution of the flow along the pipe can be investigated as well. This report documents the experiments done for co-current upwards and downwards air-water and steam-water flows as well as for counter-current air-water flows. The details of the setup, measuring technique and data evaluation are given. The report also includes a discussion on selected results obtained and on uncertainties.

Recurrent events are very common in a wide range of scientific disciplines. The majority of statistical models developed to characterise recurrent events are derived from either reliability theory or survival analysis. This thesis concentrates on applications that arise from reliability, which in general involve the study about components or devices where the recurring event is failure. Specifically, interest lies in repairable components that experience a number of failures during their lifetime. The goal is to develop statistical models in order to gain a good understanding about the driving force behind the failures. A particular counting process is adopted, the non-homogenous Poisson process (NHPP), where the rate of occurrence (failure rate) depends on time. The primary application considered in the thesis is the prediction of underground water pipe bursts although the methods described have more general scope. First, a Bayesian mixed effects NHPP model is developed and applied to a network of water pipes using MCMC. The model is then extended to a mixture of NHPPs. Further, a special mixture case, the zero-inflated NHPP model is developed to cope with data involving a large number of pipes that have never failed. The zero-inflated model is applied to the same pipe network. Quite often, data involving recurrent failures over time, are aggregated where for instance the times of failures are unknown and only the total number of failures are available. Aggregated versions of the NHPP model and its zero-inflated version are developed to accommodate aggregated data and these are applied to the aggregated version of the earlier data set. Complex devices in random environments often exhibit what may be termed as state changes in their behaviour. These state changes may be caused by unobserved and possibly non-stationary processes such as severe weather changes. A hidden semi-Markov NHPP model is formulated, which is a NHPP process modulated by an unobserved semi-Markov process. An algorithm is developed to evaluate the likelihood of this model and a Metropolis-Hastings sampler is constructed for parameter estimation. Simulation studies are performed to test implementation and finally an illustrative application of the model is presented. The thesis concludes with a general discussion and a list of possible generalisations and extensions as well as possible applications other than the ones considered.

After the development of additive manufacturing technology in the 1980s, it has found use in many applications like aerospace, automotive, marine, machinery, consumer and electronic applications. In recent time, few researchers have worked on the applications of additive manufacturing for heat transfer and fluidic devices. As the world has seen a drastic increase in population in last decades which have put stress on already scarce energy resources, optimization of energy devices which include energy storing devices, heat transfer devices, energy capturing devices etc. is need for the hour. Design of energy devices is often constrained by manufacturing constraints thus current design of energy devices is not an optimized one. In this research we want to conceptualize, design and manufacture optimized heat transfer and fluidic devices by exploiting the advantages provided by additive manufacturing. We want to benefit from the fact that very intricate geometry and desired surface finish can be obtained by using additive manufacturing. Additionally, we want to compare the efficacy of our designed device with conventional devices. Work on usage of Additive manufacturing for increasing efficiency of heat transfer devices can be found in the literature. We want to extend this approach to other heat transfer devices especially tubes with internal flow. By optimizing the design of energy systems we hope to solve current energy shortage and help conserve energy for future generation.We will also extend the application of additive manufacturing technology to fabricate "device for uniform flow distribution".