Single piles and pile groups are frequently subjected to high lateral forces. The safety and functionality of many structures depends on the ability of the supporting pile foundation to resist the resulting lateral forces. In the analysis and design of laterally loaded piles, two criterions usually govern. First, the deflection at the working load should not be so excessive as to impair the proper function of the supporting member. Second, the ultimate strength of the pile should be high enough to take the load imposed on it under the worst loading condition. Typically, pile length, pile section, soil type, and pile restraint dictate the analysis. This paper presents different methods, specifically Broms' method and the p-y method, for both the analysis and design of laterally loaded single piles. Both linear and nonlinear analyses are considered. The measured results of several full-scale field tests performed by Lymon Reese are compared to computed results using Broms' method of analysis and the p-y method of analysis. Observations are made as to the correlation between the results and recommendations are made as to the applicability of the accepted methods for the analysis and design of laterally loaded piles.

My ceramic sculptures are abstracted portraits of friends and family. They reveal no clues about the age, the gender, or the physical identity of the subjects. Instead, they are abstracted character traits rendered in clay with a biomorphic sensibility. I translate a particular personality trait of a friend or family member into a tangible object and arrange those pieces referencing botanical forms. I tend to choose the negative traits that cause friction in our relationship. My work is a way of acknowledging and dealing with the struggle these traits have caused. I structure my pieces as a floral arrangement to transfer an otherwise unfavorable experience into a positive one.

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This thesis contains an experimental investigation of the yielding behaviour of sand loaded in triaxial compression, extension and a combination of both (stress reversal). The testing programme was conducted on 102 x 205 mm medium dense samples of fine Leighton Buzzard sand. A considerable part of the work was directed towards improving the testing technique in order to obtain good quality data. For this purpose, an automated stress path system was constructed and programmed utilizing a microcomputer to take full control of the applied stresses so that any desired stress path could be closely followed in the conventional triaxial cell. Furthermore, new displacement measuring devices were developed and used throughout the testing programme for monitoring both axial and radial deformation locally on the middle third of the triaxial specimen. The results indicate that generally the behaviour of sand is highly anisotropic and that during non-reversal stress paths, the yield condition can be described by a set of curved yield loci in the p' - q stress space. Such yield loci have more curvature in extension than in compression. Stress reversal is found to cause a significant softening of the stress-strain behaviour. However, depending on the level of deviatoric prestress on the opposite side, the sand may become even softer than in the virgin stress-strain condition. The typical errors likely to occur during conventional deformation measurement are discussed, and it is concluded that the use of local measurement should replace both external axial and volumetric monitoring techniques.

Primarily because of its low cost and ease of implementation, analogue control has been the dominant control strategy in modern switch-mode power supply designs. The 'on/off' nature of power switches is essentially digital, which makes it tempting for power elec- tronics engineers to combine the emerging capability of digital technologies with existing switch-mode power supply designs. Whereas an analogue controller is usually cheaper to implement, it lacks the flexibility and capacity to implement the complex control func- tions which a digital controller can offer. The research presented in this thesis addresses the practical implementation of a digi- tal controller for a Series-Loaded Resonant Converter (SLR). The resonant frequency of the SLR converter is around 60 kHz, and the switching frequency varies up to around 80 kHz to regulate the 12V dc output voltage across a 100W, variable resistive load, from a variable 46.6V 60.2V input voltage. This provides a fair challenge for digital waveform generators as the digital processor needs to have a high clock rate to produce high speed, high resolution and linearly varying frequency square waves, to regulate the output volt- age with adequate resolution. Digital compensation algorithms also need to be efficient to minimise the phase lag caused by the instruction overhead. In order to completely understand the control needs of the SLR converter, an analogue controller was constructed using a UC3863N. The feedback compensation consists of an error amplifier in an integrator configuration. Digital control is accomplished with a TMS320F2812 Digital Signal Processor (DSP). Its high throughput of 150 MIPS provides sufficient resolution to digitally generate linearly varying frequency switching signals util- ising Direct Digital Synthesis (DDS). Time domain analysis of the switching signals, shows that the DDS generated square iv ABSTRACT waves display evidence of jitter to minute variations in pulse-widths caused by the digi- tisation process, while in the frequency domain, this jitter displays itself as additional sidebands that deteriorate the fundamental frequency of the switching signal. Overall, DDS generated square waves are shown experimentally to be adequate as control signals for the MOSFET power switches. Experiments with step load changes show the digi- tal controller is able to regulate the output voltage properly, with the drawback of the settling time being a little longer than the analogue counterpart, possibly caused by the unpredictable damping effects of switching signal jitter. Variations in input voltage shows that the digital controller excels at operating under noisier conditions, while the analogue controlled output has slightly greater noise as input voltage is increased. As the digital technology continues to improve its speed, size and capacity, as well as becoming more affordable, it will not be long before it becomes the leading form of control circuitry in power supplies.

In this research, extensive use has been made of limit equilibrium methods of analysis for studying the stability of slopes. For the determination of the factor of safety (FOS) of slopes, the usual two-step process has been adopted; (a) assuming a slip surface for the soil mass, and (b) using the appropriate limit equilibrium equation(s). Eight wellknown limit equilibrium methods have been programmed to calculate different FOS values. The comparative performance of the various analyses has been carried out successfully using case studies. The innovative use of Gauss quadrature to calculate the FOS values has been shown to reducet he iterative sequencesd ramatically with no loss of accuracy. A visco-plastic flow model has been proposed to estimate lateral forces on piles used for slope stabilisation. The present research data occupies an "in-between" position to the previously reported values, with the variation trend being confirmed satisfactorily in all cases. Slope stabilisation due to the presence of a row of piles has been investigated using two distinct lateral load estimations. These include theories of plastic deformation and the proposed visco-plastic flow which are modelled and implemented in a computer program. Eight well-known methods of slope stability analyses have been adopted and computer coded to re-calculate FOS values for a slope reinforced by a row of piles. A Finite Element computer program has been developed to evaluate the displacement, bending moment and shear force along the pile axis. The pile is analysed at two levels above and below the slip failure surface.

A full-bridge, parallel-loaded, resonant, zero current/zero voltage switching converter has been developed for DC-DC voltage transformation. The power supply was used to condition power sourced by a 28-V, 400-A Neihoff alternator installed in a HMMWV that delivered power to a 5-kW mobile radar. This design focuses on achieving maximum power density at reasonable efficiency (i.e. > 80%) by operating at the highest resonant and switching frequencies possible. A resonant frequency of 392-kHz was achieved while providing rated power. The high resonant frequency was facilitated by the development of an extremely low inductance layout (< 20 nH) capable of conducting the high resonant currents associated with this converter topology. A design methodology is presented for parallel-loaded, resonant voltage boost converters utilizing the development of a converter prototype as a basis. The experimental results are presented as validation of the methodology.

A numerical case study of a multistage compressor with relative supersonic rotors is presented. The purpose of the investigation was to determine the flow instability mechanism of the UEET compressor and its relation to the rotor shock structure in the relative velocity reference frame. The computational study was conducted with the NASA code ADPAC , utilizing the mixing-plane assumption for the boundary condition between adjacent, relatively-rotating blade rows. A steady, five-blade-row, numerical simulation using the Baldwin-Lomax turbulence model was performed, creating several constant speed lines. The results are presented, highlighting the role shock structure plays in the stability of the compressor. The shock structure in the downstream rotor isolates the upstream rotor from the exit conditions until the shock detaches from the leading edge. At this point the shock structure in the upstream rotor moves, changing the conditions for the downstream rotor. This continues with increasing pressure at the exit until the shock in the upstream rotor detaches from the leading edge. This event causes an instantaneous drop in the mass flow rate, initiating positive incident separation on the suction side of stator-two. / Master of Science

The goal of this study is to further advance the state of the art in developing self-sufficient methods to predict the performance of an aerosol filter. The simulation methods developed in this study are based on first principles and consequently, they do not rely on empirical correction factors. These simulation methods can be used to predict the instantaneous collection efficiency and pressure drop of a filter under dust-loading conditions. In the current study, 3-D micro- and macroscale CFD models are developed to simulate the service life of flat-sheet and pleated filters. These CFD micro- and macroscale models are also used to quantify the effects of a fiber’s cross-sectional shape on the performance of the resulting filter. As fiber manufacturing methods are rapidly advancing, these fibers are becoming more accessible. The filtration performance of trilobal fibers is compared with their circular counterparts under dust-loading conditions. Our results show that trilobal fibers do not outperform circular ones except in very limited conditions, revealing no advantage over circular fibers. In addition, a fast but approximate 2-D model is developed to predict the filtration performance of flat and circular pleated filters. The predictions of the model are compared with predictions from the more sophisticated CFD models, as well as with experimental work in the literature. Our 2-D model developed in this study is aimed at providing the aerosol filtration industry with a fast but fairly accurate method of designing pleated filters. With a CPU-time of practically zero, the developed model allows one to conduct a broad parameter study, altering the parameters that affect the filtration performance of pleated filters. Using this model, predictive correlations for dust-loaded pleated filters are presented. These correlations allow one to estimate the instantaneous pressure drop and collection efficiency of pleated filters effectively.

After being theorized by Veselago in 1967, recent developments in metamaterials over the last two decades have allowed scientists and researchers to physically demonstrate that artificial composite media can be engineered to exhibit exotic material properties, such as negative refractive index, by exploiting features in arrays of sub-wavelength unit inclusions. These unconventional electromagnetic properties are realized through the coupling of the microscopic unit inclusions, which govern the macroscopic properties of the structure. After demonstrating that a periodic array of capacitively-loaded loop (CLL) inclusions paired with continuous wire results in negative refraction, this study performs numerical simulations to characterize random metamaterial structures. These structures consist of CLLs that are randomized in both position and orientation. In addition, this thesis introduces an innovative antenna enhancing structure consisting of capacitively-loaded loop (CLL) metamaterial elements loaded radially around a standard dipole antenna at an electrically small distance. As a result of this innovative arrangement, the dipole antenna is easily transformed into a directive mechanically scanned antenna with high realized gain. The desired directivity and gain can be tuned based on the number of radial CLL fins placed around the dipole. Interactions between the antenna and metamaterial elements result in significant enhancement of the maximum radiated field amplitude and front-to-back ratio. This innovative CLL-loaded dipole antenna is compared to the conventional Yagi-Uda antenna. The structures presented in this thesis are modeled using full-wave simulation, and one antenna structure is experimentally verified as a proof-of-concept. / Master of Science