This thesis focused on developing a new wavelet for use with the continuous wavelet transform, a new detection method and two de-noising algorithms for rolling element bearing fault signals. The work is based on the continuous wavelet transform and implements a unique Fourier Series estimation algorithm that allows for least squares estimation of arbitrary frequency components of a signal. The final results of the research also included use of the developed detection algorithm for a novel method of estimating the center frequency and bandwidth for use with the industry standard detection algorithm, envelope demodulation, based on actual fault data. Finally, the algorithms and wavelets developed in this paper were tested against seven other wavelet based de-noising algorithms and shown to be superior for the de-noising and detection of inner and outer rolling element race faults.

Gas turbine engines are extensively used in the aviation and power generation industries. They are used as topping cycles in combined cycle power plants, or as stand alone power generation units. Gains in thermodynamic efficiency can be realized by increasing the turbine inlet temperatures. Since modern turbine inlet temperatures exceed the melting point of the constituent superalloys, it is necessary to provide an aggressive cooling system. Relatively cool air, ducted from the compressor of the engine is used to remove heat from the hot turbine blade. This air flows through passages in the hollow blade (internal cooling), and is also ejected onto the surface of the blade to form an insulating film (film cooling). Modern land-based gas turbine engines use high Reynolds number internal flow to cool their internal passages. The first part of this study focuses on experiments pertaining to passages with Reynolds numbers of up to 400,000. Common turbulator designs (45degree parallel sharp-edged and round-edged) ribs are studied. Older correlations are found to require corrections in order to be valid in the high Reynolds number parameter space. The effect of rotation on heat transfer in a typical three-pass serpentine channel is studied using a computational model with near-wall refinement. Results from this computational study indicate that the hub experiences abnormally high heat transfer under rotation. An experimental study is conducted at Buoyancy numbers similar to an actual engine on a wedge shaped model trailing edge, roughened with pin-fins and equipped with slot ejection. Results show an asymmetery between the leading and trailing surfaces due to rotation - a difference which is subdued due to the provision of pin-fins. Film cooling effectiveness is measured by the PSP mass transfer analogy technique in two different configurations: a flat plate and a typical high pressure turbine blade. Parameters studied include a step immediately upstream of a row of holes; the Strouhal number (quantifying rotor-stator interaction) and coolant to mainstream density ratio. Results show a deterioration in film cooling effectiveness with on increasing the Strouhal number. Using a coolant with a higher density results in higher film cooling effectiveness.

In this work, the effect of rotation on the oscillation frequencies of some radially and nonradially oscillating Delta-Scuti stars have been explored. Rotation has been considered as a perturbation and treated up to the second order. Series of evolutionary models have been calculated for the oscillating stars in question and compared with the observational parameters. Three stars are considered: V350 Peg with no rotation, CC And with a rotational velocity Vsini=20 km/s, and BS Tuc with Vsini=130 km/s. We find that splitting in the oscillation frequencies are conspicuous especially in fast rotating stars, with a considerable contribution from the related terms due to second order effect.

In this study we investigate the properties of trapped atoms subjected to rapid rotations. The study is divided into two distinct parts, one for fermions, another for bosons. In the case of the degenerate Fermi gas we explore the density structure of non-interacting cold atoms when they are rotated rapidly. On the other hand, for rapidly rotating two component Bose condensate, we search for new lattice structures in the presence of contact and dipolar interactions. First, the density structure of Fermi gases in a rotating trap is investigated. We focus on the anisotropic trap case, in which two distinct regimes, two and one dimensional regimes, depending on rotation frequency and anisotropy are observed. Two regimes can be illustrated by a simple description of maximum number of states between two Landau levels, which is strongly related to the dimensionality of the system. The regimes are separated from each other by a minimum point in this description. For small anisotropy values the density profiles show a step structure where each step is demonstrated by an elliptical plateau. Each plateau represents a Landau level with a constant density. The local density approximation describes the two dimensional regime with a perfect similarity in the structure of fermion density. The case for one dimensional regime is a little different from the two dimensional case. For large anisotropy values the Friedel oscillation is the dominant aspect of the density profiles. The density profiles show gaussian structure along the direction of strong trapping, and a semicircular form with prominent oscillations along the weak confining direction. Again, the system is nicely described by local density approximation in this regime. A smooth crossover between two regimes is observed, with a switching from a step structure profile to a soft edge transition with Friedel oscillations. At finite temperatures, the step structures are smeared out in two dimension. In one dimensional regime the Friedel oscillations are cleaned as soon as the temperature is turned on. The second part of the study is devoted to the investigation of different lattice structures in two component Bose condensates subjected to very fast rotation, this time in the presence of interactions. We explore the existence of new vortex lattice structures for dipolar two component condensates scanning a wide range of interaction strengths. We introduce a phase diagram as a function of intra and inter-component interactions showing different type of vortex lattice structures. New types of lattice structures, overlapped square and overlapped rectangular, emerge as a result of dipolar interactions and s-wave interaction for a two component condensate. The region where the attractive inter-component interactions dominate the repulsive interactions, the overlapped lattices are formed. The intra-component interactions, which defines the behavior of each component inside, result in different type of lattices by changing the strength of interactions. Two different limits of phase diagram reproduce the results of ordinary two component and dipolar one component Bose condensates. The results of calculation are in agreement with the results of previous studies for two regimes.

No description available.

This thesis numerically studied mass transfer during fully confined liquid jet impingement on a rotating target disk of finite thickness and radius. The study involved laminar flow with jet Reynolds numbers from 650 to 1500. The nozzle to plate distance ratio was in the range of 0.5 to 2.0, the Schmidt number ranged from 1720 to 2513, and rotational speed was up to 325 rpm. In addition, the jet impingement to a stationary disk was also simulated for the purpose of comparison. The electrochemical fluid used was an electrolyte containing 0.005moles per liter potassium ferricyanide (K3(Fe(CN6)), 0.02moles per liter ferrocyanide (FeCN6?4), and 0.5moles per liter potassium carbonate (K2CO3). The rate of mass transfer of this electrolyte was compared to Sodium Hydroxide (NaOH) and Hydrochloric acid (HCl) electrochemical solutions. The material of the rotating disk was made of 99.98% nickel and 0.02% of chromium, cobalt and aluminum. The rate of mass transfer was also examined for different geometrical shapes of conical, convex, and concave confinement plates over a spinning disk. The results obtained are found to be in agreement with previous experimental and numerical studies. The study of heat transfer involved a microchannel for a composite channel of trapezoidal cross-section fabricated by etching a silicon wafer and bonding it with a slab of gadolinium. Gadolinium is a magnetic material that exhibits high temperature rise during adiabatic magnetization around its transition temperature of 295K. Heat was generated in the substrate by the application of magnetic field. Water, ammonia, and FC-77 were studied as the possible working fluids. Thorough investigation for velocity and temperature distribution was performed by varying channel aspect ratio, Reynolds number, and the magnetic field. The thickness of gadolinium slab, spacing between channels in the heat exchanger, and fluid flow rate were varied. To check the validity of simulation, the results were compared with existing results for single material channels. Results showed that Nusselt number is larger near the inlet and decreases downstream. Also, an increase in Reynolds number increases the total Nusselt number of the system.

AEgIS is an experiment at CERN where the goal is to directly measure the gravitational force on antimatter by producing antihydrogen. The antihydrogen will be produced by a charge exchange reaction using laser excited positronium and cold antiprotons. Having a well-characterized positron plasma with at least 108 positrons and knowing how it can be controlled is essential for the positronium production. This thesis is based on the goals of AEgIS experiment and describes the positron plasma manipulations being used in AEgIS in order to achieve the required plasma properties for the experiment. The positron system is made up by a source, a Surko trap and a Penning-Malmberg trap. This system was first optimized to increase the number of positrons. The plasma was then moved to the main traps of the experiment where it was systematically characterized in terms of lifetime, cooling efficiency and compression. Positron plasma compression in time, trapping and cooling was tested for the first time in AEgIS using a buncher and Penning-Malmberg traps respectively. In this thesis, it is shown that a compression of more than 50 % in time of the positron cloud using a buncher can be achieved. It is also shown that trapping and cooling with an efficiency of nearly 100 % in the main traps using a “V” shaped potential trap was successful. On top of that, the lifetime inside this “V” shaped potential trap was observed to be longer than 30 minutes.

The effect of rotation on flow in a gas turbine blade cooling duct model is investigated experimentally. The present work consists of velocity measurements at different locations in a test section with a 180° bend with ribs on one wall. Three geometric rib parameters are considered; rib-rib spacing, rib orientation angle and rib blockage ratio. PIV is used for flow visualization and analysis. Along with the clean duct measurements, ribs with blockage ratios, b/h, of 0.25 and 0.125 were considered. The b/h = 0.25 cases have been comprehensively analyzed while the b/h = 0.125 cases have been studied at the post-bend region of the duct only. Reynolds number considered is in the range of approximately 5000-40,000 and the rotation speed is varied for a rotation number from 0 to 7. It is observed that rotation has a significant effect on secondary flows within the rotating duct. For blockage ratio, b/h = 0.25, at a constant Re and Ro, the RMS of fluctuations of velocity do not show large spatial variations with ribs or rib orientations. At higher Re, the value decreases in comparison to the low Re cases. The kinetic energy of fluctuations increases due to the presence of ribs, indicating better heat transfer for the ribbed duct, but do not show large variations with rib orientation angle. The fluctuations and kinetic energy show maximum values at the post-bend regions of the duct. The velocity fields and PDFs show a possible cause for e°cient heat transfer for the 45° rib arrangement as compared with the 90° rib cases. At high Ro, the absolute value of circulation has a large increase at the post-bend and thereafter there is a gradual decay at the exit for all cases. The ribs with blockage ratio of b/h = 0.125 showed no marked changes in circulation with changes in rib orientation angle, thus implying that the rib blockage plays a role in the generation of secondary flows, particularly in conjunction with rotation.

Acid treatments have predominantly been conducted using HCl for its availability, high rock dissolving power and soluble reaction products. At high temperatures, rapid spending of the acid with carbonates prevents deeper penetration distance into the formations. Alternative fluids such as acetic and formic acid have lent themselves to retarded reaction rates, low corrosivity and reduced tendency to form acid/oil sludge in asphaltene-rich crudes but for high reaction rate problems. Chelating agents, with the added advantage of complexing with alkali-earth metals in carbonates to form water-soluble products that are thermally stable at high temperature, have been introduced as stimulation fluids. Glutamic acid diacetic acid (GLDA) ethylenediaminetetraacetic acid (EDTA) and hydroxyethylenediaminetriacetic acid (HEDTA) are aminopolycarboxylic acids that were studied. To predict the spending of chelating agents relative to simple organic acids at temperatures between 150 and 250˚F, the chemical kinetics of dolomite dissolution in these acid solutions were investigated over different reaction conditions in a rotating disk apparatus. Samples of the reacted acids from the reactor were collected and then analyzed with inductively coupled plasma (ICP). Analyses of the experimental data were carried out to determine kinetic parameters of the heterogeneous reactions needed for matrix stimulation of dolomitic reservoirs. Experimental results indicated that dolomite dissolution rates increased in all the acid solutions as the disk rotational speeds increased at 150, 200, and 250˚F. The dissolution of dolomite in 0.886 M GLDA was found to be surface-reaction limited at lower temperatures and mass-transfer limited at highest temperature. GLDA with the lowest reaction rates and relative diffusion coefficient demonstrated retardation before spending with deeper penetration capability for productivity and injectivity improvement.

No description available.