Vehicle suspension systems have been extensively explored in the past decades, contributing to ride comfort, handling and safety improvements. The new generation of powertrain and propulsion systems, as a new trend in modern vehicles, poses significant challenges to suspension system design. Consequently, novel suspension concepts are required, not only to improve the vehicle’s dynamic performance, but also to enhance the fuel economy by utilizing regeneration functions. However, the development of new-generation suspension systems necessitates advanced suspension components, such as springs and dampers. This Ph.D. thesis, on the development of hybrid electromagnetic dampers is an Ontario Centres of Excellence (OCE) collaborative project sponsored by Mechworks Systems Inc. The ultimate goal of this project is to conduct feasibility study of the development of electromagnetic dampers for automotive suspension system applications. With new improvements in power electronics and magnetic materials, electromagnetic dampers are forging the way as a new technology in vibration isolation systems such as vehicle suspension systems. The use of electromagnetic dampers in active vehicle suspension systems has drawn considerable attention in the recent years, attributed to the fact that active suspension systems have superior performance in terms of ride comfort and road-handling performances compared to their passive and semi-active counterparts in automotive applications. As a response to the expanding demand for superior vehicle suspension systems, this thesis describes the design and development of a new electromagnetic damper as a customized linear permanent magnet actuator to be used in active suspension systems. The proposed electromagnetic damper has energy harvesting capability. Unlike commercial passive/semi-active dampers that convert the vibration kinetic energy into heat, the dissipated energy in electromagnetic dampers can be regenerated as useful electrical energy. Electromagnetic dampers are used in active suspension systems, where the damping coefficient is controlled rapidly and reliably through electrical manipulations. Although demonstrating superb performance, active suspensions still have some issues that must be overcome. They have high energy consumption, weight, and cost, and are not fail-safe in case of a power break-down. Since the introduction of the electromagnetic dampers, the challenge was to address these drawbacks. Hybrid electromagnetic dampers, which are proposed in this Ph.D. thesis, are potential solutions to high weight, high cost, and fail-safety issues of an active suspension system. The hybrid electromagnetic damper utilizes the high performance of an active electromagnetic damper with the reliability of passive dampers in a single package, offering a fail-safe damper while decreasing weight and cost. Two hybrid damper designs are proposed in this thesis. The first one operates based on hydraulic damping as a source of passive damping, while the second design employs the eddy current damping effect to provide the passive damping part of the system. It is demonstrated that the introduction of the passive damping can reduce power consumption and weight in an active automotive suspension system. The ultimate objective of this thesis is to employ existing suspension system and damper design knowledge together with new ideas from electromagnetic theories to develop new electromagnetic dampers. At the same time, the development of eddy current dampers, as a potential source for passive damping element in the final hybrid design, is considered and thoroughly studied. For the very first time, the eddy current damping effect is introduced for the automotive suspension applications. The eddy current passive damper, as a stand-alone unit, is designed, modeled, fabricated and successfully tested. The feasibility of using passive eddy current dampers for automotive suspension applications is also studied. The structure of new passive eddy current dampers is straightforward, requiring no external power supply or any other electronic devices. Proposed novel eddy current dampers are oil-free and non-contact, offering high reliability and durability with their simplified design. To achieve the defined goals, analytical modeling, numerical simulations, and lab-based experiments are conducted. A number of experimental test-beds are prepared for various experimental analyses on the fabricated prototypes as well as off-the-shelf dampers. Various prototypes, such as eddy current and electromagnetic dampers, are manufactured, and tested in frequency/time domains for verification of the derived analytical and numerical models, and for proof of concept. In addition, fluid and heat transfer analyses are done during the process of the feasibility study to ensure the durability and practical viability of the proposed hybrid electromagnetic dampers. The presented study is only a small portion of the growing research in this area, and it is hoped that the results obtained here will lead to the realization of a safer and more superior automotive suspension system.

Vehicle suspension systems have been extensively explored in the past decades, contributing to ride comfort, handling and safety improvements. The new generation of powertrain and propulsion systems, as a new trend in modern vehicles, poses significant challenges to suspension system design. Consequently, novel suspension concepts are required, not only to improve the vehicle’s dynamic performance, but also to enhance the fuel economy by utilizing regeneration functions. However, the development of new-generation suspension systems necessitates advanced suspension components, such as springs and dampers. This Ph.D. thesis, on the development of hybrid electromagnetic dampers is an Ontario Centres of Excellence (OCE) collaborative project sponsored by Mechworks Systems Inc. The ultimate goal of this project is to conduct feasibility study of the development of electromagnetic dampers for automotive suspension system applications. With new improvements in power electronics and magnetic materials, electromagnetic dampers are forging the way as a new technology in vibration isolation systems such as vehicle suspension systems. The use of electromagnetic dampers in active vehicle suspension systems has drawn considerable attention in the recent years, attributed to the fact that active suspension systems have superior performance in terms of ride comfort and road-handling performances compared to their passive and semi-active counterparts in automotive applications. As a response to the expanding demand for superior vehicle suspension systems, this thesis describes the design and development of a new electromagnetic damper as a customized linear permanent magnet actuator to be used in active suspension systems. The proposed electromagnetic damper has energy harvesting capability. Unlike commercial passive/semi-active dampers that convert the vibration kinetic energy into heat, the dissipated energy in electromagnetic dampers can be regenerated as useful electrical energy. Electromagnetic dampers are used in active suspension systems, where the damping coefficient is controlled rapidly and reliably through electrical manipulations. Although demonstrating superb performance, active suspensions still have some issues that must be overcome. They have high energy consumption, weight, and cost, and are not fail-safe in case of a power break-down. Since the introduction of the electromagnetic dampers, the challenge was to address these drawbacks. Hybrid electromagnetic dampers, which are proposed in this Ph.D. thesis, are potential solutions to high weight, high cost, and fail-safety issues of an active suspension system. The hybrid electromagnetic damper utilizes the high performance of an active electromagnetic damper with the reliability of passive dampers in a single package, offering a fail-safe damper while decreasing weight and cost. Two hybrid damper designs are proposed in this thesis. The first one operates based on hydraulic damping as a source of passive damping, while the second design employs the eddy current damping effect to provide the passive damping part of the system. It is demonstrated that the introduction of the passive damping can reduce power consumption and weight in an active automotive suspension system. The ultimate objective of this thesis is to employ existing suspension system and damper design knowledge together with new ideas from electromagnetic theories to develop new electromagnetic dampers. At the same time, the development of eddy current dampers, as a potential source for passive damping element in the final hybrid design, is considered and thoroughly studied. For the very first time, the eddy current damping effect is introduced for the automotive suspension applications. The eddy current passive damper, as a stand-alone unit, is designed, modeled, fabricated and successfully tested. The feasibility of using passive eddy current dampers for automotive suspension applications is also studied. The structure of new passive eddy current dampers is straightforward, requiring no external power supply or any other electronic devices. Proposed novel eddy current dampers are oil-free and non-contact, offering high reliability and durability with their simplified design. To achieve the defined goals, analytical modeling, numerical simulations, and lab-based experiments are conducted. A number of experimental test-beds are prepared for various experimental analyses on the fabricated prototypes as well as off-the-shelf dampers. Various prototypes, such as eddy current and electromagnetic dampers, are manufactured, and tested in frequency/time domains for verification of the derived analytical and numerical models, and for proof of concept. In addition, fluid and heat transfer analyses are done during the process of the feasibility study to ensure the durability and practical viability of the proposed hybrid electromagnetic dampers. The presented study is only a small portion of the growing research in this area, and it is hoped that the results obtained here will lead to the realization of a safer and more superior automotive suspension system.

A novel computational approach, Two Level Simulation (TLS), was developed based on the explicit reconstruction of the small-scale velocity by solving the small-scale governing equations on the domain with reduced dimension representing a collection of one-dimensional lines embedded in the three-dimensional flow domain. A coupled system of equations, that is not based on an eddy-viscosity hypothesis, was derived based on the decomposition of flow variables into the large-scale and the small-scale components without introducing the concept of filtering. Simplified treatment of the small-scale equations was proposed based on modeling of the small-scale advective derivatives and the small-scale dissipative terms in the directions orthogonal to the lines. TLS approach was tested to simulate benchmark cases of turbulent flows, including forced isotropic turbulence, mixing layers and well-developed channel flow, and demonstrated good capabilities to capture turbulent flow features using relatively coarse grids.

Phased array coils are composed of several surface coils receiving individual element signals simultaneously. Each individual surface coil provides the equivalent of the coil diameter range, and higher SNR. Therefore, combining these non-interactive phased array coils, can achieve a wide range of scan areas, uniform sensitivity and better SNR. Therefore our experiment was performed with two different coils of quadrature coil and phased array coil. Phased array MRS data were compared using various combination approaches. Data acquired by quadrature coil was regarded as a standard to verify the reliability and accuracy of metabolite concentration. The aim of our study is to do eddy current correction before and after the combination of each element coil data with LCModel analysis for quantitative comparison of metabolite concentrations. Our result shows that doing eddy current correction for each phased array coil before signal combination can achieve higher reliability and accuracy of SNR and quantitative concentrations of MR spectra in vivo.

Satellite-tracked surface drifter data from 1986 to 2008 acquired from NOAA/AOML and the sea-level anomaly (SLA) data of AVISO from 1992-2008 were used in this study to investigate the mesoscale anticyclonic eddies in the northern South China Sea (SCS) and Luzon Strait. A comparison of the concurrent drifter trajectories and SLA for two eddy events (2003/12~2004/02 and 2004/11~2005/01) indicates good agreement between the two datasets. From historical SLA data (1992-2008) it is found that 78 anticyclonic eddies can be identified in the studied region. The number of occurrence is highest in 1994, 1996, 2001 and 2004, and is lowest in 1998. This result is likely due to the ENSO event and the associated wind lessening in the SCS. Most eddies were generated off southwestern Taiwan coast, northern SCS and west of Luzon Strait. During northeastern monsoon the average life time of eddies is 66.88 days, and the average sea level height difference is 10-20 cm, occasionally reached a maximum value of over 30 cm. During southwestern monsoon eddies have an average lifetime of 51.43 days, and the average sea level height difference is mostly less than 15 cm. In particular, eddies off the southwestern Taiwan coast have the characteristics of lower sea level height difference and translational speed. Location of eddy generation has a marked seasonal variation. During northeastern monsoon, most eddies were concentrated in northern Luzon Strait, propagating longer distance toward the west along the continental shelf, even reaching 112¢XE. On the other hand, eddies generated during the southwestern monsoon can only reach 118¢XE. Statistical results indicate a linear relationship exists between the sea level height difference and the life time for eddies, implying that stronger eddies are more long-lived. Finally, from drifter tracks it can be found that as Kuroshio penetrates through the Luzon Strait and forms a loop current off the southwestern Taiwan coast. Subsequently, eddies could often be identified from the SLA data. Therefore, it can be conjectured that in the northern SCS anticyclone are often shed from the Luzon Strait by Kuroshio penetration.

This study investigates the turbulent mixing characteristics of Peng-hu Channel, South China Sea along 21¢XN and the Kuroshio region by using CTD/LADCP and MicroRider. Dissipation rate of turbulent kinetic energy or thermal variances is estimated primarily by the Thorpe overturn method, and is compared with the microstructure turbulence from direct measurement as well as those estimated from the parameterization method based on shear and strain spectra. Our results indicate that there are different turbulent characteristics and dynamic mechanisms at these three regions. Because of its funnel-shaped topography and strong semi-diurnal tides in the Peng-hu Channel, the turbulent mixing and eddy diffusivity reach a maximum value at the narrowest part of Peng-hu Channel near its sea bottom and show a clear tidal variation. In the main stream of Kuroshio where the current speed is faster than 0.8 m/s, turbulent mixing is not particularly stronger than non-main stream zone. In the Kuroshio frontal zone between the Kuroshio and the coastal waters off east Taiwan coast, strong turbulent mixing in the surface layer can be detected. Island wake which is formed when Kuroshio runs into the Lan-yu Island is a transient feature. Strong mixing in the upper 100 m accompanied with upwelling and vortices were observed during one event. The topography along the latitude of 21¢XN is rugged and rough in the Luzon Strait which consists of several ridges and seamounts. Due to its complicated topography and generation of strong semi-diurnal internal tides, eddy diffusivity as high as 10^(-2)m^2/s was measured in the bottom layer of the Luzon Strait.

Road and rail vehicles and aircraft rely mainly or solely on friction brakes. These brakes pose several problems, especially in hybrid vehicles: significant wear, fading, complex and slow actuation, lack of fail-safe features, increased fuel consumption due to power assistance, and requirement for anti-lock controls. To solve these problems, a contactless magnetic brake has been developed. This concept includes a novel flux-shunting structure to control the excitation flux generated by permanent magnets. This brake is wear-free, less-sensitive to temperature than friction brakes, has fast and simple actuation, and has a reduced sensitivity to wheel-lock. The present dissertation includes an introduction to friction braking, a theory of eddy-current braking, analytical and numerical models of the eddy-current brake, its excitation and power generation, record of experimental validation, investigation and simulation of the integration of the brake in conventional and hybrid vehicles.

Eddy current testing is a non-destructive testing method that has usually used for examination of carbon steel tubes. By using a high frequency electromagnetic field on the exciting probe, it is easy to figure out the impedance variation of the coil on impedance plane, and estimate the crack depth by measuring the angle of curve. However, different kind of tubes and electromagnetic properties resulted in different testing. The purpose of this study is to create the two dimensional axial symmetry model of eddy current testing by finite element software package FEMLAB. And it is easy to estimate the crack depth by figuring the impedance plane and evaluation curves by MATLAB. Furthermore, the research analyzed the variation of curves and angles on an impedance plane and tried to reduce testing errors. Over all, the analysis of some influence factors of eddy current testing in the present study not only provides a standard of estimating crack depth more accurately, but also reduces the evaluation errors.

A numerical study of the flow field generated by injection through diamondshaped orifices into a high-speed flow is presented in this document. Jet interaction flows have a wide range of applications in the field of engineering. These applications include the use of jets for fuel injection in scramjets, for reaction control of high-speed aerodynamic bodies and as cooling jets for skins of high-speed vehicles. A necessary requirement in the use of transverse jets for these and other applications is a thorough understanding of the physics of the interaction between the jet and freestream. This interaction generates numerous flow structures that include multiple shocks, vortices, recirculation regions and shear layers. This study involves diamond-shaped orifices that have the advantage of generating weaker or attached interaction shocks as compared to circular injectors. These injectors also negate the effects due to the recirculation region that is formed upstream of the injector. This study was undertaken in order to gain further understanding of the flow features generated by diamond-shaped injectors in a high-speed flow. Numerical simulations were performed using two different levels of turbulence models. Reynolds™ Averaged Navier-Stokes (RANS) simulations were performed using the GASP flow solver while Detached-Eddy Simulation (DES) runs were performed using the Cobalt flow solver. A total of fifteen diamond injector simulations were performed using the RANS model for a 15 half-angle diamond injector. The fifteen simulations spanned over five different injection angles and three jet total pressures. In addition to these, two circular injector simulations were also performed. In addition, low pressure normal injection through diamond and circular orifices simulations were performed using DES. Results obtained from CFD were compared to available experimental data. The resulting flow structure and the turbulent properties of the flow were examined in detail. The normal injection case through the diamond-shaped orifice at the lowest jet total pressure was defined as the baseline case and is presented in detail. In order to study the effect of different components of the vorticity transport equation, an in-house code was used post-process the results from the RANS runs.

Eddy current testing is a widely-used examination of the nondestructive testing method. According to the theory of electromagnetic induction, the coil impendence varies with the interaction between the coil magnetic field and the eddy current magnetic field. By observing the variations of the phase angle and the impendence plane diagram, the influence of different defects and factors are evidently presented. The purpose of this study is to analyze the three-dimensional defects of eddy current testing by means of the finite element method. To begin with, a complete 3-D electromagnetic model in eddy current testing by finite element software package COMSOL Multiphysic was created. Then the impendence plane diagram and evaluation curves are drawn by the mathematics software package MATLAB to show the variations of the impendence and the phase angle. Moreover, the results show the effect of reducing testing errors. The simulation of 3-D defect model can provide more comparable data for experimentalists. So that the problem of inappropriate judgement can be prevented, and then the accuracy in eddy current testing can be enhanced.