Doctor of Philosophy (PhD), Wright State University, 2013, Engineering PhD

Many integrated circuits are connected to their packaging pins through bondwires. Due to the low cost of bondwires, there is interest in extending operating frequencies or negating their effects in order to keep the price of packaged integrated circuits as low as possible. Bondwires function as lumped circuits consisting of inductors, capacitors, and resistors which can be modeled based on wire geometry. Knowing this, models can be created which approximate the effects of bondwires. With the knowledge of these models, compensation techniques can be implemented which will match the bondwire impedance to the signal line impedance. The effects of these elements on circuit operation is apparent on both signal and power lines to devices. This dissertation is going to present 1. A bondwire model based on physical characteristics of interconnections including neighboring wires. The model is tested against data from fabricated test fixtures, and results compared to those produced by current software. 2. A compensation method for performance degradation caused by bondwires at radio frequencies. Test fixtures implementing these methods are fabricated and checked with results compared to predictions. 3. A method of component stacking which can be used to attach passive components directly to IC die. -Use of above method to improve power distribution network (PDN) performance. Theoretical results are compared to measured test fixture results. -Use of above method to improve performance of off device filters through Q-factor improvement. Improvement verified through test and analysis of a physical test fixture.

Committee: Saiyu Ren Ph.D. (Advisor); Raymond Siferd Ph.D. (Committee Member); Marty Emmert Ph.D. (Committee Member); Marian Kazimierczuk Ph.D. (Committee Member); Ronald Coutu Ph.D. (Committee Member) Subjects: Electrical Engineering; Engineering

Master of Science, The Ohio State University, 2024, Civil Engineering

Extreme weather events continually challenge the integrity of transmission lines, necessitating robust predictive models for grid resilience. This thesis presents two comprehensive data-driven approaches to assess and predict wind-induced transmission line interruptions, leveraging advanced machine learning techniques and innovative data sampling methods. In the first phase, predictive models that establish reliable associations between weather, environmental factors, and line characteristics to forecast interruptions are developed. A novel event-based sampling approach is introduced to address the challenges of unbalanced datasets, improving model accuracy by identifying input subspaces that are most challenging for classification. Among various machine learning models tested, XGBoost demonstrated the highest predictive accuracy of 93.5\%. Sensitivity analyses using Shapley values underscored the importance of wind gust, line length, and mean sea pressure in interruption events. These models offer valuable insights for real-time outage mitigation and long-term planning for line reinforcement and resource allocation during extreme weather events. The second phase enhances the best-performing model from the first phase by addressing class imbalance through novel GAN model created by combining advanced synthetic data generation using Conditional Tabular GAN (CTGAN) augmented with InfoGAN methodologies. Additionally, to make use of the large synthetic data created generated by the model, an adapted Query by Committee (QBC) active learning framework is proposed. The method strategically selects the most informative data points from the large pool of real and synthetic data points, optimizing model performance. When compaing our developed model with a model trained using conventional methods, our model showed a substantial increase of 5\% in testing accuracy for typical testing datasets and an even bigger increase of 17\% when presented with a more challenging test (open full item for complete abstract)

Committee: Abdollah Shafieezadeh (Advisor); Jieun Hur (Committee Member); Chen Chen (Committee Member) Subjects: Civil Engineering; Computer Science

Doctor of Philosophy, The Ohio State University, 2019, Materials Science and Engineering

Metal-rich primers have been used for corrosion protection on metals for over 40 years. Recently, researchers started to investigate the use of metal-rich primers on aluminum alloys as an alternative to hexavalent-chromate systems because of their good corrosion-protective properties. The active aluminum-rich primer (AlRP) was invented and developed at NAVAIR (Patuxent River, MD) to protect aluminum alloys and steels. The Al alloy (Al-Zn-In) pigments in AlRP were fabricated from a sacrificial anode alloy, which has a lower open circuit potential (OCP) than common aluminum alloys. However, initial results indicated that the pigment particles in AlRP tended to undergo severe self-corrosion. Therefore, the Al pigments are pretreated in a trivalent chromium passivation (TCP) bath to reduce the self-corrosion rate. The objectives of this study are to understand the corrosion protection properties of AlRP on aluminum alloy 2024-T3 substrate and to evaluate the effect of TCP treatment on the Al pigment particles. The polarization curves of AA2024-T3 and the active aluminum alloy (Al-Zn-In) show that TCP-treated active aluminum alloy has a lower corrosion potential than AA2024-T3 and thus would cathodically protect it. AlRP-coated samples were exposed in accelerated exposure tests, GMW14872 and B117. Exposed samples were then examined using scanning electron microscopy and energy dispersive X-ray spectroscopy to understand the coating degradation process. In addition, samples were immersed in 0.1M NaCl solution for an extended time and were monitored using electrochemical impedance spectroscopy. The AlRP with TCP-treated pigments out performs the coating with untreated pigments. The TCP treatment on the Al-Zn-In pigments was evaluated. The chemistry and morphology of Al pigment particles treated in a TCP bath for three different immersion times were characterized using X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and ener (open full item for complete abstract)

Committee: Gerald Frankel (Advisor); Jenifer Locke (Committee Member); Narasi Sridhar (Committee Member) Subjects: Materials Science

Doctor of Philosophy, The Ohio State University, 2018, Electrical and Computer Engineering

A well-planned electric transmission network is essential for attaining an effective electricity market and the reliable operation of the associated power system. In this dissertation, we address the transmission expansion planning (TEP) problem. The goal of the thesis work is to develop models and algorithms to help system planners to identify optimal investments in the transmission network. First, we propose a candidate-line selection algorithm based on a set of systematic rules to generate an appropriate candidate-line set for TEP studies. The expertise of system planners and the characteristics of a network are both considered for candidate-line selection. Second, we develop an adaptive robust stochastic optimization model for TEP problems that specifically differentiates long- and short-term uncertainties. The long-term uncertainty pertains to year-to-year changes including the peak demand and available generating capacity of the system during the planning target year. Then, within the target year, the short-term uncertainty pertains to the production of weather-dependent renewable capacity and the load. Next, we expand the adaptive robust stochastic optimization model to consider the coordinated investment in transmission and storage facilities. Such model provides an effective tool to identify the best trade-off between these two types of facilities. Finally, we conclude by providing conclusions, contributions and suggestions for future work.

Committee: Antonio Conejo (Advisor); Ramteen Sioshansi (Committee Member); Mahesh Illindala (Committee Member) Subjects: Electrical Engineering

Master of Science, University of Akron, 2014, Chemical Engineering

Aluminum 2024-T3 and 7075-T6 are commonly used in aviation industry. The coating application on the aluminum surface is consider as one of the most effective method to ease the corrosion problem. Hex-chrome free coating which has less environmental issues was developed in recent years. In this work, we studied the degradation process of hex-chrome free coating/ aluminum system under the constant immersion environment with the help of a proposed damage evolution concept. This damage evolution concept includes four steps: 1. Initial water uptake process within coating layer, 2. Activation of electrochemical reaction in the coating and metal interface 3. Propagation of corrosion products below coating layer, coating delamination or degradation. 4. Coating totally fails, metal experiences severe metal loss. Three experimental variables were investigated in this project, they were: pH of electrolyte, top coat thickness, and metal effect. Impedance measurements of samples immersed in 3.5 wt% NaCl electrolyte were continually carried out for 160 days to study the impact of those experimental variables. A two dimensional transmission line model was developed in this work. This 2D-TLM was firstly verified via comparing the simulated EIS data with experimental results. A further application of this model gave us a local impedance distribution of hex-chrome free coating/aluminum profile. Via interpreting the local impedance distribution, a detailed degradation mechanism of sample in early immersion period was revealed.

Committee: Homero Castaneda-Lopez Dr. (Advisor); Scott Lillard Dr. (Committee Member); Hongbo Cong Dr. (Committee Member) Subjects: Chemical Engineering

Master of Science in Engineering, University of Akron, 2014, Chemical Engineering

The susceptibility of pipeline to soil corrosion is always minimized by imposing an insulating barrier or coating at the pipe surface, and protection is enhanced by cathodic protection (CP) using either a sacrificial anode bed or an impressed current in case there are some defects or holidays on the coating surface. However, disbonding and/or delamination of the coating can still result in serious localized corrosion, because the cathodic current cannot penetrate under a delaminated coating and the uncovered sites become susceptible to localized corrosion. This work aims to identify and characterize the damage evolution of pipeline with intact and defect coal tar coating under cathodic protection in soil or NS4 solution, measured by electrochemical impedance spectroscopy (EIS). The transmission line model (TLM) was used to simulate the EIS results and to verify the proposed damage evolution. The results demonstrated that in soil, for the pipeline with intact coal tar coating, the assumed process, corresponding to three stages, would be adsorption of water and soil particles to the surface of the coating and water and ions to the interior coating, diffusion of water and ions to the interface of coating and steel, and relatively saturated electrolyte in the interface before the steel suffers corrosion. In soil, for pipe with defect coating, corrosion products were initially formed at the coating holiday. After long term exposure the mass transfer mechanism became the dominant process, as opposed to diffusion, due to the corrosion product covering the holiday surface that increased the impedance. For intact coating in homogeneous NS4 solution, the first two stages were detected: there was water uptake within the coating layer and the impedance decreased with time due to the damage evolution of each element forming the electrochemical cell. For defect coating in NS4 solution, impedance decreased over time until corrosion products covered the holiday surface, (open full item for complete abstract)

Committee: Homero Castaneda-Lopez Dr. (Advisor); Scott Lillard Dr. (Committee Member); Hongbo Cong Dr. (Committee Member) Subjects: Chemical Engineering

MS, University of Cincinnati, 2005, Engineering : Computer Engineering

Accurate simulation of lossy transmission lines with skin effects has always been difficult or at least inefficient. Although modeling lossy transmission lines without skin effects can be carried out efficiently and accurately, including accurate skin effect model either affect accuracy or efficiency. Skin effect is accurately approximated using the simple form A+B√s at high frequencies, i.e. when s is large. However, this form is not passive. Passivity guarantees stability. Since a transmission line is a passive device, its model should also be passive such that the simulation depending on it is stable. If skin effect is approximated by A+B√s and directly incorporated into a model, the simulation based on that model may become unstable. In this thesis, a method to generate a passive, accurate and compact model for a lossy transmission line with skin effect is introduced. The method is developed on a RLC lumped equivalent circuit of a transmission line. By applying a passive model order reduction algorithm and exploring the properties of the transmission line equivalent circuit, we found out a novel way to map the model reduction process into solving integrals. By matching moments implicitly, a passive and accurate model for a lossy transmission line with skin effect can be generated rapidly.

Committee: Dr. Harold Carter (Advisor) Subjects:

Doctor of Philosophy, The Ohio State University, 2011, Electrical and Computer Engineering

Emerging broadband applications are pushing for the need to build high data rate wireless transceivers at 60GHz for high volume low cost mobile devices. Central to the success of implementing such transceivers is the robust design of 60GHz CMOS RF front ends, especially the low noise amplifiers (LNAs). In the future, CMOS technology is expected to enable low-cost mm-wave applications such as high data-rate communication links, passive and active imaging and sensor systems, and instrumentation and measurements equipment. Building highly integrated inexpensive mm-wave CMOS devices requires high quality factor lumped and distributed passives with accurate and scalable transistor and passives models. My research work focuses on demonstrating a methodology for generating a scalable compact model for on-chip transmission lines and interconnects on lossy silicon substrate. The model is demonstrated over 20-60 GHz frequency band using two types of transmission lines built in TSMC's 0.18 µm CMOS technology. Several CPWs and Microstrip lines are designed with different lengths to verify the accuracy and scalability of the extracted model. The compact model shows an excellent agreement with measured data with maximum deviation in S11 magnitude and phase of 9.2% and 5.6%, respectively, and maximum deviation in S21 magnitude and phase of 10.1% and 6.6%, respectively. Compared to existing model extraction methodologies, the required time for generating the compact model and simulating transmission lines is reduced significantly. The generated models are fully compatible with all commercial circuit simulators. This work presents key design techniques for different CMOS mm-wave LNA topologies. The proposed LNA topologies are, the three-stage cascode RF NMOS configuration and four-stage Common Gate followed by Common Source configuration. Simulation results for 60GHz LNAs show that the first topology can achieve a peak gain of 16.67 dB with a 3-dB bandwidth of 7 GHz, and a noise fig (open full item for complete abstract)

Committee: Mohammed El-Naggar PhD (Advisor); Waleed Khalil PhD (Advisor); Patrick Roblin PhD (Committee Member); Donald Houser PhD (Committee Member) Subjects: Electrical Engineering

Doctor of Philosophy, The Ohio State University, 2010, Electrical and Computer Engineering

Recent interest in new materials, including metamaterials and magneto-dielectrics, for RF applications provided strong impetus for measurement techniques to characterize associated permittivity, permeability, and loss factors. Traditional measurement techniques are not readily available to characterize these engineered composites. For example, conventional resonant cavity methods are known to be narrowband and require careful sample preparation. For metamaterials and magneto-dielectrics, broadband characterization is particularly necessary to observe their dispersive properties. Also, a challenge with new materials, such as layered composites, is the restriction in measurable shape, size and thickness. Often, small and irregularly shaped samples are available, making their characterization challenging. With these issues in mind, this dissertation is aimed at developing new characterization techniques for novel engineered composites. Specifically, four techniques are presented to characterize textured metamaterial volumetric structures, magneto-dielectric mixtures and films, and highly conductive metallo-dielectric films. One of the presented techniques is based on a Gaussian beam illumination. In this method, the Gaussian beam is used to illuminate the center of layered material samples to avoid diffraction from sample edges. In contrast to generating the Gaussian beam using bandwidth-limited lenses, the beam was reconstructed by scanning a probe over a virtual aperture much like the synthetic aperture radar process. This approach was successfully employed at X-band (8 to 12 GHz) for the characterization of slow-wave propagation in a layered metamaterial slab. However, the Gaussian beam method is not feasible at low frequencies as it requires a large sample aperture (> 1-wavelength in size). The second characterization method was, therefore, developed to measure smaller samples (< 0.25-wavelength) in lower frequencies (100 MHz to 4.8 GHz). More specifically, a str (open full item for complete abstract)

Committee: John L. Volakis (Committee Chair); Kubilay Sertel (Committee Co-Chair); Joel T. Johnson (Committee Member); Ronald M. Reano (Committee Member) Subjects: Electrical Engineering; Electromagnetism

Master of Science, The Ohio State University, 2010, Mechanical Engineering

This study presents an improved gear noise source model with surface undulation or roughness as the main excitation while taking into account the sliding frictional contacts between meshing teeth. This model extends the prior linear time-varying model that predicted the surface roughness-induced air-borne noise source. The structure-borne noise source is examined in this study by employing a six degree of freedom linear time-varying model. Gear contact mechanics is used to determine the mesh stiffness variation and also to relate the surface undulation to an equivalent static transmission error over a range of torques. Four alternate dynamic sliding friction models are also compared. Sound pressure radiated by the casing via structure-borne noise path is predicted using experimental partial pressure to acceleration transfer functions given pinion and gear accelerations in the line of action and the off-line of action direction. Linear time-invariant models are also developed by assuming that the mesh stiffness, moment arm and coefficient of friction do not vary with time. Sinusoidal, periodic and random tooth surface undulations are examined and sound pressures at gear mesh harmonics are predicted; the random undulation also generates off gear mesh frequency components. Both linear time-varying and linear time-invariant models are utilized to quantify the structure-borne noise sources and to understand the role of mesh stiffness, moment arm and coefficient of friction variations. The effects of torque, surface undulation amplitude, coefficient of friction and speed are also examined by using the linear-time varying model. Noise predictions (especially the trends) are compared with prior literature and some plausible explanations regarding the dominant sources are provided.

Committee: Dr. RAJENDRA SINGH (Advisor); Dr. AHMET KAHRAMAN (Committee Member) Subjects: Acoustics; Engineering; Mechanical Engineering

Master of Science (MS), Ohio University, 1989, Electrical Engineering & Computer Science (Engineering and Technology)

Magnetic fields of an underground coaxial cable caused by return currents in the earth

Committee: H. HIll (Advisor) Subjects:

Master of Science, Miami University, 2011, Physics

We present experimental research on magneto-transport at Copper and GaMnAs interface. We report the values of specific contact resistance (ARc) between GaMnAs/Cu interfaces using Circular Transmission Line Method (CTLM) for a wide range of temperature (15K to 290K) above and below Curie temperature (Tc) which is at 145K. Our values of specific contact resistance are very low and close to the order of ~10-8 Ωcm2 which agrees with literature and changes abruptly to close to double of the value at Curie temperature when GaMnAs has phase transition between nonmagnetic to ferromagnetic. We suggest that this arises due to suppression of one of the two spin conduction channels when the phase transition of GaMnAs takes place. We also found the Specific contact resistance has a peak shifted towards lower temperature which suggests the magnetization in the GaMnAs film is suppressed near the Copper interface.

Committee: Khalid Eid PhD (Advisor); Michael Pechan PhD (Committee Member); Jan Yarrison-Rice PhD (Other); Herbert Jaeger PhD (Other) Subjects: Physics