Doctor of Philosophy, Case Western Reserve University, 2022, EECS - Electrical Engineering

This thesis shows that permanent magnets and electromechanical control systems can enable power-efficient, high-sensitivity, low-noise modalities for spectroscopy and wireless communication. Specifically I present two examples. The first is a radio frequency (RF) spectrometer which uses a detector cooled to 77 K to maximize measurement sensitivity, coupled with a minimally-intrusive network of active duplexers and mechanical contact switches to realize a reconfigurable series/parallel resonant network. I present a receiver which combines the highly sensitive analog frontend instrumentation with a mixed signal embedded system to monitor and control secondary processes. The cryogenic system increases the measurement signal to noise ratio (SNR) by a factor of 10×. The second example is an extremely low frequency (ELF) communication system which uses a mechanically-rotated dipole instead of an electrical antenna to generate the oscillating field of the transmitter. I show how a synchronous digital controller can maintain stable control over the dynamic process while a complementary embedded system modulates the set-point and monitors the channel. My transmitter achieves a power efficiency 7.6× greater than an equivalent electrical antenna in a device small enough to be moved by one person. I carry the transmitter into a cave and demonstrate cave-to-surface message transmission through 15 m of rock and frozen soil in a real-world field test. I present each solution in the context of scientific and human motivation, and explore tradeoffs required to achieve design goals. Emphasis is also placed on whether there exists a position of harmony and balance, where one may reasonably proclaim the optimum implementation has been achieved. The receiver is relatively more complex than the transmitter in the case of RF spectroscopy. In the case of ELF communication it is the reverse.

Committee: Soumyajit Mandal (Advisor); Wyatt Newman (Committee Member); Robert Brown (Committee Member); Kenneth Loparo (Committee Member) Subjects: Electrical Engineering; Electromagnetics; Electromagnetism; Engineering; Mechanical Engineering; Mechanics; Nuclear Physics

Master of Science in Electrical Engineering (MSEE), Wright State University, 2024, Electrical Engineering

This research illustrates a high-security wireless communication method using a joint radar/communication waveform, addressing the vulnerability of traditional low probability of detection (LPD) waveforms to hostile receiver detection via cyclostationary processing (CSP). To mitigate this risk, RF steganography is used, concealing communication signals within linear frequency modulation (LFM) radar signals. The method integrates reduced phase-shift keying (RPSK) modulation and variable symbol duration, ensuring secure transmission while evading detection. Implementation is validated through software-defined radios (SDRs), demonstrating effectiveness in covert communication scenarios. Results include analysis of message reception and cyclostationary features, highlighting the method's ability to conceal messages from hostile receivers. Challenges encountered are discussed, with suggestions for future enhancements to improve real-world applicability.

Committee: Zhiqiang Wu Ph.D. (Advisor); Xiaodong Zhang Ph.D. (Committee Member); Bin Wang Ph.D. (Committee Member) Subjects: Electrical Engineering

Doctor of Philosophy, Case Western Reserve University, 2020, Organizational Behavior

Firms are challenged to achieve organizational goals in an environment of increasingly decentralized information. Cross-functional project teams are employed widely as a strategy to facilitate better coordination, yet projects still fail at a rate of 31% per year. Communication is a leading cause of failure. While inter-team communication has been studied extensively, less is understood about the intra-team communication of a cross-functional project team. The main finding of our study is that the success of a cross-functional team is dependent on the team's ability to inquire across multiple knowledge boundaries in a way that develops an awareness of each other's functional identity. Functional identity is defined as the norms and practices of a functional team which represent how they think about and prioritize their work. Whether or not this functional-identity knowledge-sharing process occurs determines whether a cross-functional team is able to construct a shared reality with respect to the projects' goals and priorities. Achieving a shared reality is what enables a team to perform successfully. We call the understanding of another's functional identity, constructed through a process of inquiry by the project team's members, their achievement of interpretive symmetry. Our findings are from an integrated mixed-methods study. Qualitative results from Study 1 began with the consideration that cross-functional team members live in two social worlds, that of the project team and that of their own functional team. Boundaries on a project exist both from a knowledge and a social membership perspective. Therefore, team members must engage in a process of inquiry across these boundaries. We found that successful teams have a receptive awareness that the project team does not “know” and needs to learn. This receptivity supported the team members in their open inquiry with one another and the sharing of not only functional knowledge but functional identity. Exposing t (open full item for complete abstract)

Committee: Richard Boland (Committee Chair); Phil Cola (Advisor); David Aron (Advisor); Yunmei Wang (Advisor) Subjects: Behavioral Psychology; Behavioral Sciences; Business Administration; Business Community; Cognitive Psychology; Communication; Information Technology; Management; Organization Theory; Organizational Behavior; Philosophy of Science; Social Psychology; Social Research; Social Structure; Sociology; Sustainability; Technology

MS, University of Cincinnati, 2002, Engineering : Electrical Engineering

In this thesis, the performance of a decorrelating-based multiuser detector for frequency-selective channels is discussed. The users transmit data at two different rates are instead of one single rate. According to their transmission rates, the users are classified into two groups, a group of high rate users and a group of low rate users. It is assumed that over the time interval [0, T o ], the low rate users transmit one bit, while the high rate users transmit M bits of information. At the receiving end, two types of decorrelators are examined to decode the signals: a low rate decorrelator (LRD) and a high rate decorrelator (HRD). The LRD makes a decoding decision for every T o seconds and views one high rate user as M effective low rate users. The HRD makes a decision for every T 1 = T o / M seconds and detects a bit from a low rate user M times during the time interval[0, T o ]. The signals from the two groups are transmitted over frequency-selective multipath Rayleigh fading channels. The maximal ratio combining (MRC) technique is used in two parts of the receivers. First, the multipath diversity and MRC diversity reception method are utilized in the receivers to combat against the multipath fading. Secondly, in HRD, MRC is employed to implement a soft decoding rule for the low rate users.The error probability and asymptotic multiuser efficiency for both types of decorrelators will be evaluated and the simulation results given. It can be seen in the simulation results that the LRD is superior to the HRD in the performance for both low rate and high rate users.

Committee: Dr. James Caffery, Jr. (Advisor) Subjects:

Doctor of Philosophy, The Ohio State University, 2019, Electrical and Computer Engineering

This dissertation presents a new technology for batteryless and wireless neurorecording system which can be applied clinically. Two clinical issues of this type of neural implant are the 1) multichannel operation and 2) high impedance and DC voltage offset from the brain electrode impedance. To resolve these two problems, one wireless multichannel system and one brain electrode interface impedance-matching system are proposed respectively. To achieve multichannel operation, one photo-activated multiplexer is employed in the implant circuit. The interrogator additionally sends an infrared control signal for channel selection. Experimental results show that the proposed neuropotential recorder exhibits 20 uVpp sensitivity at all eight channels. The system is also in compliance with the strictest Federal Communications Commission standards for patient safety. Notably, the proposed approach is scalable to a much higher number of channels. On the other hand, to mitigate the high impedance and DC voltage offset of the brain-electrode interface, one self-biasing PNP Bipolar Junction Transistor (BJT) is adopted in the brain circuits. This self-biasing PNP BJT increases the overall system's impedance and maintains the system sensitivity while the high impedance is present. Measurement results demonstrate that emulated neuropotentials as low as 200 uVpp can be detected at a 33 kOhms electrode impedance. Together, these proposed techniques would lead the wireless neuro recorders to be applicable in real, in-vivo clinical applications.

Committee: John L. Volakis (Advisor); Asimina Kiourti (Advisor); Liang Guo (Committee Member); Daniel Rivers (Committee Member) Subjects: Biomedical Engineering; Electrical Engineering; Electromagnetics

Doctor of Philosophy (PhD), Ohio University, 2015, Electrical Engineering & Computer Science (Engineering and Technology)

Today's nanochips contain billions of transistors on a single die that integrates whole electronic systems as opposed to sub-system parts. Together with ever higher frequency performances resulting from transistor scaling and material improvements, it thus become possible to include on the same silicon chip analog functionalities and wireless communication circuitry that was once reserved to only an elite class of compound III-V semiconductors. It appears that the last stretch of Moore's scaling down to 5 nm range, these systems will only become more capable and faster, due to novel types of transistor geometries and functionalities as well as better integration of passive elements, antennas and novel isolation approaches. Accordingly, this dissertation is an example to how RF-CMOS integration may benefit from the use of a novel multi-gate transistors called FinFETs or Double Gate Metal Oxide Semiconductor Field Effect Transistors (DGMOSFETs). More specifically, this research is to validate how the performance of the radio frequency wireless communication integrated circuits can be improved by the use of this novel transistor architecture. To this end, in this dissertation, a wide range of radio frequency integrated circuits have been investigated in DG-MOSFETs which include Oscillators, On Off Keying (OOK) Modulator, Power Amplifier, Low Noise Amplifier, Envelope Detector, RF Mixer and Charge Pump Phase Frequency Detector. In all cases, the use of DG-MOSFET devices lead to reduction of transistor count and circuit complexity, while also resulting in tunable circuits owing to local back-gate control available in this device structure. Hence this work provides a unique insight as to how modest geometry changes and 3D device engineering may result in significant gains in analog/RF circuit engineering in the last stretch of Moore's scaling.

Committee: Savas Kaya (Advisor) Subjects: Electrical Engineering

Master of Science in Electrical Engineering, Cleveland State University, 2013, Fenn College of Engineering

VDL Mode 2 is the principal data communication technology for aeronautical communications implemented in the NextGen project for the National Airspace System (NAS), with potentially worldwide service. Aeronautical communications have strict transmission delay standards for safety considerations. Meeting the strict standards significantly drops the capacity of the number of aircraft that can communicate using the Very High Frequency (VHF) Data Radio (VDR). In this thesis, three methods of increasing the capacity while maintaining the strict standards are evaluated: transmit power control, load regulation and ground station placement. A simulation model using OPNET software is used for testing. Load regulation shows some improvement, while transmit power control is not beneficial. The best results are obtained from optimal ground station placement, with over 300 percent capacity improvement in certain scenarios.

Committee: Vijaya Konangi Ph.D. (Committee Chair); Fuqin Xiong Ph.D. (Committee Member); Nigamanth Sridhar Ph.D. (Committee Member) Subjects: Aerospace Engineering; Electrical Engineering; Engineering; Technical Communication

Master of Science (MS), Bowling Green State University, 2008, Communication Disorders/Speech-Language Pathology

Purpose: The goal of this project was to categorize the fundamental frequency and durational patterns of chinchilla (laniger) vocal productions relative to typical interaction situations. Methods: This project focused on 4 distinct call types: Exploratory, Contact, Bark, and Alarm from three sources: doctoral dissertation supplements, pet owner posts, and newly collected samples from a single chinchilla. Praat was used to extract the fundamental frequency (F0) contour from the recordings. Results: Primary characteristics of the Exploratory utterances were: token Fo contours had a rapid decrease in frequency (136 ST/s), (2) token durations and token periods overlapped to a large extent across animals, 77% of all tokens contained a final Fo up-sweep tag, and utterances contained an average of 9 tokens. The Contact utterances contained 2-4 Exploratory-like tokens preceding a few transitional tokens, segueing into a sequence of the Contact tokens, Fo contours were complex, variable, and low pitched (300-800 Hz), there is a typical brief low Fo dip of less than an octave from the preceding and following Fo, and the utterances contained an average of approximately 7. Bark utterances were characterized by a brief tonal segment followed by a distinctive noise interval, an abrupt intensity onset followed by a more gradual intensity offset, an increase in token period duration across the utterance, an intensity decrease across the tokens, with a variant of the Bark category including an inspiratory tone preceding or following the token, and the utterances contained an average of 6 tokens. The Alarm utterance token was a high intensity call that included a large, very rapid frequency jump, and maintained a high intensity throughout.

Committee: Ronald Scherer PhD (Advisor); Laura Dilley PhD (Committee Member); Donald Cooper PhD (Committee Member) Subjects: Acoustics; Communication