This thesis presents the results of a study that uses Incremental Dynamic Analysis to assess the seismic performance of steel moment-resisting frames with fluid viscous dampers subjected to earthquake ground motions. The study systematically investigated the effects of linear and nonlinear dampers on the response of steel moment-resisting frames to earthquakes that varied in intensity and type. Both near-field and far-field motions were considered. Two different types of nonlinear dampers were investigated; one had a hardening and the other had a softening force-velocity relationship. The nonlinear dampers were calibrated to the linear dampers so that there was a basis of comparison. Maximum damper displacement is one of the parameters of the calibration, and it was varied to investigate its effect on structural response. Several nonlinear inelastic time history analyses were performed to obtain responses, such as peak base shear, peak interstory drift, or residual displacement index, which were plotted versus earthquake intensity to create individual IDA curves. Sets of related IDA curves provide a useful summary of the structural behavior for a wide range of variables. IDA curves for the tests with different damping types are presented. The results show that for both near-field and far-field ground motions the nonlinear dampers with a hardening force-velocity relationship are best suited to reduce undesirable drifts and residual displacements; however, these reductions come at the cost of high base shear forces. / Master of Science

With the advent of wide bandgap (WBG) semiconductor devices, the electromagnetic interference (EMI) emissions are more pronounced due to high slew rates in the form of high dv/dt and high di/dt at higher switching frequencies compared to the traditional silicon technology. To comply with the stringent conducted emission requirements, EMI filters are adopted to attenuate the high frequency common mode (CM) and differential mode (DM) noise through the propagation path. However, self and mutual parasitic components are known to degrade the EMI filter performance. While parasitic cancellation techniques have been discussed at length in prior literature, most of them have focused mainly on single phase applications. As such this work focuses on extending the preexisting concepts to three-phase systems. Novel component placement, winding strategy as well as shielding and grounding techniques were developed to desensitize the influence of the parasitic effects on a three-phase multi-stage filter. The effectiveness of the three-phase filter structure employing the proposed methodologies has been validated via noise measurements at the line impedance stabilization network (LISN) in a 15kW rated motor drive system. Consequently, general design guidelines have been formulated for filter topologies with different inductor and capacitor form-factors. / Master of Science / The adoption of wide bandgap (WBG) semiconductor devices, such as Silicon Carbide (SiC) or Gallium Nitride (GaN) transistors, improves the power density with higher slew rates and switching frequencies compared to the traditional Silicon technology. However, the high switching speeds and high frequencies have generated higher electromagnetic interference (EMI) noise in the surroundings. To comply with the conducted emission requirements at the grid terminal, EMI filter is mandatory to attenuate the high frequency EMI noise that flows into grid. However, near field and the effect of parasitic components are known to degrade the filter performance at the higher end of frequency spectrum where the limit lines are typically stringent. While parasitic cancellation techniques have been discussed at length in prior literature, most of them has focused mainly on single phase applications. Therefore, this thesis aims to extend the pre-existing concepts to compensate the mutual and self-parasitic coupling components in a three-phase multi-stage filter. In this regard, novel component placement, winding strategy as well as shielding and grounding techniques were developed to compensate for the parasitic effects in a three- phase multi-stage filter. The effectiveness of the three-phase filter structure employing the proposed methodologies has been validated in a 15kW rated motor drive system. Consequently, general design guidelines have been formulated for filter design with minimal parasitic effects.

The propagation symmetry of electromagnetic fields is affected by encounters with material systems. The effects of such interactions, for example, modifications of intensity, phase, polarization, angular spectrum, frequency, etc. can be used to obtain information about the material system. However, the propagation of electromagnetic waves imposes a fundamental limit to the length scales over which the material properties can be observed. In the realm of near-field optics, this limitation is overcome only through a secondary interaction that couples the high-spatial-frequency (but non-propagating) field components to propagating waves that can be detected. The available information depends intrinsically on this secondary interaction, which constitutes the topic of this study. Quantitative measurements of material properties can be performed only by controlling the subtle characteristics of these processes. This dissertation discusses situations where the effects of near-field interactions can be (i) neglected in certain passive testing techniques, (ii) exploited for active probing of static or dynamic systems, or (iii) statistically isolated when considering optically inhomogeneous materials. This dissertation presents novel theoretical developments, experimental measurements, and numerical results that elucidate the vectorial aspects of the interaction between light and nano-structured material for use in sensing applications.

No description available.

No description available.

No description available.

Yes / The potentially broad application area in engineering design using Genetic Al- gorithm (GA) has been widely adopted by many researchers due to its high consistency and accuracy. Presented here is the initial design of a wideband non-dispersive wire bow-tie antenna using GA for breast cancer detection applications. The ultimate goal of this design is to achieve minimal late-time ringing but at higher frequencies such as that located from 4 to 8 GHz, in which is desire to penetrate human tissue for near field imaging. Resistively loading method to reduce minimal ringing caused by the antenna internal reflections is implemented and discussed when the antenna is located in free space and surrounded by lossy medium. Results with optimised antenna geometry and di®erent number of resistive loads are presented and compared with and without existence of scatterers.

Research presented herein involved the use of a smart skin treatment used for the attenuation of turbulent boundary layer induced interior noise. The treatment consisted of several Smart Foam actuators each having a reference and error sensor along with a feed forward, filtered-x controller. Studies were performed to determine if the use of multiple instances of single input, single output (SISO) control systems could be implemented with success given the difficulty of actively suppressing turbulent boundary layer induced interior noise. Further, this research will lead to the development of an integrated Smart Foam element consisting of a Smart Foam actuator, reference sensor, error sensor and SISO controller in one complete, stand--alone unit. Several topics were studied during this effort: reference sensing, error sensing, actuator design, controller causality, correlation of turbulent flow and resulting plate vibration, and coherence between plate vibration and the interior noise field. Each study was performed with the goal of improving the performance of active attenuation of turbulent boundary layer induced interior noise. Depending on the configuration of the control system, control was performed using either experiments or simulations based on experimental data. Within the desired control band of 400--800~Hz, attenuation of up to -3.1~dB$_A$ was achieved at the error sensors and up to -1.4~dB$_A$ within the observer plane relative to the uncontrolled case. However, over a band of greater coherence from 480--750~Hz, attenuation of up to -4.8~dB$_A$ was achieved at the error sensors and up to -2.6~dB$_A$ within the observer plane. Further, peak attenuation of up to -12~dB$_A$ was achieved within the observer plane. Studies were also conducted to increase the low frequency performance of the Smart Foam treatment. These experiments used tuning masses placed on the tops of the integrated Smart Foam elements to tune them to the fundamental mode of the vibrating plate. This treatment was used to reactively attenuate plate vibration such that the radiated acoustic field would be minimized. These experiments resulted in -6~dB$_A$ global attenuation at the plate fundamental resonance. Further, it was shown that the reactive treatment did not inhibit active control. / Ph. D.

As ubiquitous wireless communication becomes part of life, the demand on antenna miniaturization and interference reduction becomes more extreme. However, antenna size and performance are limited by radiation physics, not technology. In order to understand antenna radiation and energy storage mechanisms, classical and alternative viewpoints of radiation are discussed. Unlike the common sense of classical antenna radiation, it is shown that the entire antenna fields contribute to both radiation and energy storage with varying total energy velocity during the radiation process. These observations were obtained through investigating impedance, power, the Poynting vector, and energy velocity of a radiating antenna. Antenna transfer functions were investigated to understand the real-world challenges in antenna design and overall performance. An extended model, using both the singularity expansion method and spherical mode decomposition, is introduced to analyze the characteristics of various antenna types including resonant, frequency-independent, and ultra-wideband antennas. It is shown that the extended model is useful to understand real-world antennas. Observations from antenna radiation physics and transfer function modeling lead to both corrections and extension of the classical fundamental-limit theory on antenna size. Both field and circuit viewpoints of the corrected limit theory are presented. The corrected theory is extended for multi-mode excitation cases and also for ultra-wideband and frequency-independent antennas. Further investigation on the fundamental-limit theory provides new innovations, including a low-Q antenna design approach that reduces antenna interference issues and a generalized approach for designing an antenna close to the theoretical-size limit. Design examples applying these new approaches with simulations and measurements are presented. The extended limit theory and developed antenna design approaches will find many applications to optimize compact antenna solutions with reduced near-field interactions. / Ph. D.

The objective of the present study was to acquire a better understanding of parameters controlling the species generation and transport from compartment fires. The experiments were performed in a half-scale ISO 9705 compartment and a 6.1 m long hallway connected in a head-on configuration. The buoyancy driven propane fire was provided by a burner and a continuous gaseous fuel supply system. All the measurements were obtained during the steady state of the fire. The ventilation conditions were fixed and three different fire source elevations were studied for heat release rates ranging from 20 kW to 150kW. The species yields were obtained from performing detailed mapping measurements at the compartment and hallway exit planes. The measurements included local specie mole fractions of oxygen, carbon dioxide, carbon monoxide and unburned hydrocarbons. The local temperature and the local pressure (for local gas velocity calculations) were also measured. In addition, visual observations of the flow dynamic were performed through a window and the vents to give useful insights and lead to a better understanding of the combustion process. The data obtained from the species generation study was analyzed using previously developed methods. The method based on equivalence ratio was presented and determined inappropriate for the present study where the global equivalence ratio was not equal to the plume equivalence ratio due to the complexity of the fire dynamic taking place. The method consisting of correlating the species yields based on the combustion within the compartment as a function of a non dimensional heat release rate allowed qualitative conclusions to be made. The non-dimensional heat release rate was based on the fuel load and the geometric parameters of the compartment. This methodology revealed similarities in the species production between the three fire source elevations investigated. A correlation of the data was obtained based on experimental data. The transport of species to remote locations was studied for the three fire source elevations and fixed ventilation conditions. Species mole fractions and yields were obtained at the compartment exit plane (compartment/hallway interface) and at the hallway exit plane. The results were compared for various heat release rates and showed differences for some scenarios attributed to mixing along the hallway and oxidation reactions outside the compartment. / Master of Science