Master of Science in Computer Science, Miami University, 2025, Computational Science and Engineering

Wireless ad hoc networks (WANETs) are an essential development in providing high-speed data transfer in areas with little to no infrastructure. The conjunction of this technology with free space optical (FSO) transceivers has not only increased the speed of communication but has also greatly decreased the cost of implementation. Because FSO transceivers are highly directional, the problem of neighbor discovery in such systems has posed challenges in accuracy and runtime. In this thesis, we produce a novel neighbor discovery protocol using a supplementary omnidirectional channel and integrate an attack-detection method against several common network-layer attacks. We present an innovative approach that utilizes a low-bitrate, long-range (LoRa) omnidirectional communication channel to assist in coordinating the neighbor discovery process, allowing for the synchronization and establishment of directional FSO links among nodes. Secondly, provide a solution that utilizes the inherent properties of directional transceivers in order to implement attack detection in the neighbor discovery process.

Committee: Suman Bhunia (Advisor); Honglu Jiang (Committee Member); Khodakhast Bibak (Committee Member) Subjects: Computer Science

Master of Science, Miami University, 2024, Physics

Quantum entanglement – a strange correlation that can exist between quantum particles (irrespective of distance) where the measurement of the state of one particle instantaneously decides the state(s) of the other particle(s) has remained a central topic in the foundations of quantum mechanics since several decades. This phenomenon, which has no classical counterpart, has gained a renewed interest in recent decades when it was shown that entanglement can be used as an information resource in many quantum-enabled information technologies. This thesis focuses on studying the evolution of entanglement among quantum bits or qubits (building blocks in quantum information theory). In particular, under realistic conditions, we examine how different open quantum system models impact the dynamics and generation of entanglement when these qubits interact with their environment. To this end, using the machinery of quantum Langevin equations, input-output formalism, and master equations, we present a thorough analysis of free-space entanglement among qubits with vacuum-, Fock-, and thermal-state environments. Both entanglement dynamics and generation have been explored using a combination of analytic and numerical techniques.

Committee: Imran Mirza (Advisor); Edward Samson (Committee Member); Samir Bali (Committee Member); Caleb Eckhardt (Committee Member) Subjects: Physics

PHD, Kent State University, 2024, College of Education, Health and Human Services / School of Foundations, Leadership and Administration

This qualitative study used an interpretative phenomenological analysis framework (Smith et al., 2012) to explore the ways in which U.S. public university chancellors and presidents experience campus free speech and safe space. Six public university leaders with campus free speech and safe space experience participated in semi-structured interviews in 2022. The resulting analyses included exploration of participants' perceptions and sensemaking, in addition to the double hermeneutic relative to researcher sensemaking (Smith et al., 2012). The findings indicated that participants viewed free speech as foundational to civilized society. Participants emphasized the academy's role in protecting and promoting free speech, while fostering safe spaces for learning and intentional dialogue. The impact of sociopolitical, geographic, and historical contexts on participants' free speech and safe space experiences, perceptions, and sensemaking was highlighted, in addition to the impact of university stakeholders. Additionally, participants demonstrated similarities in their sensemaking relative to campus free speech and safe space, often engaging characteristics of balancing, collaborating, leading, learning, mentoring, and responding. The findings suggest several implications for university leadership. The development of deep and diverse stakeholder relationships, in addition to support systems with others experienced in the presidential role, would be useful for informing leaders' free speech and safe space sensemaking and decision making. Additionally, the need for leadership training on issues related to balancing campus free speech and safe space considerations was also identified.

Committee: Stephen Thomas (Committee Chair); Tricia Niesz (Committee Member); Tara Hudson (Committee Member) Subjects: Higher Education

Master of Science (M.S.), University of Dayton, 2023, Electro-Optics

Free space optical (FSO) communication has gained interest for a long time due to its ability to have secure transmission and high data rates. Interest has increased in using beams carrying orbital angular momentum (OAM) for FSO communication, due to their (theoretically) infinite number of orthogonal modes and potential high resistance to atmospheric turbulence. Theory of OAM beams and atmospheric turbulence are discussed in detail in this study. In this experimental study, Laguerre-Gaussian (LG) beams are used as OAM beams and LG beams of different order are generated using a spatial light modulator (SLM). Moreover, the method used to generate a LG beam is also included. Besides, a wave-optics simulation method is used to generate phase screens containing simulated atmospheric turbulence, which in turn are used on two SLMs to generate atmospheric turbulence in our experimental set up. In this study, beams with different order of OAM are propagated through (simulated) atmospheric turbulence, using seven different strengths. The distorted beam is recorded using a CCD camera and the images are processed to determine their beam size, intensity, and on-axis scintillation. The least square method which is the mathematical analysis to determine the beam size and scintillation are explained in this thesis. The effect of the strength of atmospheric turbulence on different orders of LG beams and the behavior of different OAM mode in same atmospheric turbulence has been analyzed using these beam parameters. In addition, experimental results are compared with simulation results, which were obtained using a split-step method. Results have shown that in different strengths of atmospheric turbulence, the beam size shows similar behavior, and that a low OAM mode, due to its smaller beam size, is hardly detectable in stronger atmospheric turbulence. However, larger order OAM modes tend to be more resistant to atmospheric turbulence due to a larger beam size, it gives relatively lo (open full item for complete abstract)

Committee: Miranda van Iersel (Advisor); Partha Banerjee (Committee Member); Thomas Weyrauch (Committee Member) Subjects: Optics

Master of Science (MS), Wright State University, 2023, Biological Sciences

Invasive species threaten ecosystems and economies. Globally, biological invasions are estimated to have cost over $2.1 trillion since 1970. In Eastern North American woodlands, invasive plants are rapidly displacing natives. This is concerning, because invasive plants may not support the diverse and abundant arthropod communities essential to ecosystem function. Despite the conceptual understanding of invasive shrubs' potential to transform forest communities, scant research has focused on the effect of invasive plants on higher trophic levels here in Ohio. To address this gap, I examined the diversity and abundance of arthropod communities, caterpillar performance, and caterpillar predation on two invasive shrubs, Amur honeysuckle (Lonicera maackii) and border privet (Ligustrum obtusifolium), relative to native counterparts. Lo. maackii supported a depauperate community; however, Li. obtusifolium hosted a surprisingly robust community. Nevertheless, both invasives proved poor hosts for caterpillars and were less preferred by foraging insectivores.

Committee: John O. Stireman III, Ph.D. (Advisor); Don Cipollini Jr., Ph.D. (Committee Member); Volker Bahn Ph.D. (Committee Member) Subjects: Biology; Ecology; Entomology; Environmental Science; Plant Sciences; Zoology

Doctor of Philosophy (PhD), Ohio University, 2022, Electrical Engineering & Computer Science (Engineering and Technology)

Integrating highly directional optical radios into next generation wireless systems is increasingly gaining traction due to the potential benefits to be derived from the several terahertz (THz) of spatially reusable spectrum available. In this dissertation, we explore three main research problems within the domain of laser-based free space optical networks and which fall under the broader areas of optimal multicast, neighbor discovery and link quality indication. For the optimal multicast problem, we show that the static version of this problem is an abstraction of the minimum weight set cover problem which is known to be NP-hard. A computationally cheap greedy local optimum heuristic is then proposed which has a time complexity of O(N) compared to the O(N^2) time complexity of the well known O(log N) approximation algorithm to the set cover problem. We then proceed to the version of the optimal multicast problem in mobile scenarios, and show that it is an abstraction of the time dependent prize collecting traveling salesman problem which is NP-hard. In formulating our problem, we develop a novel prize assignment strategy that guarantees the selection of mutually disjoint multicast sets. Due to the problem being NP-hard, we provide several potential heuristics for multicast in mobile scenarios. We evaluate the performance of these multicast algorithms in delay tolerant networking conditions, and in a typical 5G backhaul network. For the multicast problem, we assumed that nodes knew the transceiver orientations of recipients via the dissemination of coordinates obtained via the global positioning system (GPS) over a low rate omnidirectional radio frequency (RF) channel. However, in delay averse and high throughput self configuring networks, nodes might not possess GPS capabilities. In addition, they might not have a control channel. Agile neighbor discovery in such situations is then of critical importance. Given an optical wireless network with MicroElectroMechan (open full item for complete abstract)

Committee: Harsha Chenji (Advisor) Subjects: Computer Engineering; Computer Science; Electrical Engineering

Master of Science (M.S.), University of Dayton, 2021, Electro-Optics

This research project compares the performance of a Monolithic Optical Receiver and a Multi Aperture Receiver, in order to reduce optical power fluctuations induced by a Gaussian beam traveling through atmospheric turbulence. In this this work a mathematical model to describe the effects of focal spot wander and aperture averaging is provided, in order to explain the reduction of scintillation by increasing the area of an optical receiver. In particular, the Churnside model is used due to its simplicity to describe the effect of aperture averaging as a function of the collection diameter for receiving optical systems. In other hand, the steps for the alignment of Multi Aperture Receiver systems are shown. In this section, interferometric tests are used to align each aperture of this optical receiver system, and thereby achieve a correct multimode fiber optic coupling of the Gaussian beam received after propagating through atmospheric turbulence. At the same time, a finder scope is attached, which aims to align the multi aperture receiver system with the optical axis of the Gaussian beam propagated through an atmospheric channel. iv This work proposes a set of five experiments which use the normalized variance of the received power as a figure of merit, to compare the fluctuations of power received with both optical collectors in different conditions of atmospheric turbulence. The atmospheric channel used in practice is described in detail, and consists of a 7km optical path in the city of Dayton Ohio, which is subjected to tests in different conditions of atmospheric turbulence, that changes depending on the time of day in which measurements are done. In the case of the Multi Aperture Receiver system, it has been possible to define an effective diameter to compare the increase in sub-apertures with the increase in the total diameter of a monolithic system. With this, it has been possible to introduce a new concept called "sub-apertures averaging", referring to t (open full item for complete abstract)

Committee: Mikhail Vorontsov PhD (Advisor); Marija Strojnik PhD (Committee Chair); Thomas Weyrauch PhD (Advisor) Subjects: Atmosphere; Atmospheric Sciences; Optics

Master of Science (M.S.), University of Dayton, 2020, Electro-Optics

In this work, simulations of propagation of helical Ince-Gauss beams, elliptical solutions of the paraxial wave equation that carry orbital angular momentum, were performed in order to see how the nature of these modes affects their performance as information carrying beams in free space optical communication systems. Special attention was put in to the effects that the order "p", degree "m" and ellipticity "ε" parameters, and their evolution, have on the robustness of the beam, finding that for a given mode, the chose of basis in which it is projected (ellipticity value) does not heavily affect the light spatial mode performance as information carrier and is instead more heavily affected by the combination of "p", "m" and their difference p−m for the chosen helical Ince-Gauss mode. These results were obtained by varying propagation parameters such as the refractive index structure parameter or propagation distances and using different beam structure parameters as the mentioned "p", "m" and "ε". From the simulations, both intensity and phase transverse profiles were recovered as well as propagation measurements such as the fidelity of the modes, and specially defined scintillation index and strehl ratio. Additionally, the generation of these vortex beams using spatial light modulators was demonstrated, showing the evolution of the modes with the ellipticity "ε" parameter and proposing the detection of these modes using their near-field intensity profile, as it shows more clearly the distribution of the intensity optical vortexes of the modes.

Committee: Qiwen Zhan PhD. (Advisor); Roberto Ramírez Alarcón PhD. (Advisor); William Plick PhD. (Committee Member); Imad Agha PhD. (Committee Member) Subjects: Atmosphere; Optics; Physics; Quantum Physics

PHD, Kent State University, 2017, College of Arts and Sciences / Department of Mathematical Sciences

In this dissertation we study discrete versions of several classical problems in convex geometry. First among these is a natural extension of Alexander Koldobsky's slicing inequality, which is an equivalent question to the isomorphic version of the Busemann-Petty problem for arbitrary measures. For our study we take the discrete measure of the cardinality of the lattice points inside a body. Our results give an asymptotic bound depending only on the dimension, and that the bound must be such in the case of unconditional bodies. We also investigate questions related to the volume product of convex bodies. In particular, we explore what the maximal volume product is for polytopes with a fixed number of vertices. It turns out that the body which yields the maximal volume product must be a simplex. Finally, we explore a more discrete version of the volume product that comes from associating the space of Lipschitz functions over a metric space to a symmetric polytope with conditions on its vertices, called the unit ball of the Lipschitz-free space. We then relate the maximal and minimal balls of such spaces to special graphs associated to the metric space.

Committee: Artem Zvavitch (Advisor); Matthieu Fradelizi (Advisor); Dmitry Ryabogin (Committee Member); Fedor Nazarov (Committee Member); Feodor Dragan (Committee Member); Jonathan Maletic (Committee Member) Subjects: Mathematics

Master of Science in Engineering (MSEgr), Wright State University, 2015, Mechanical Engineering

The ability to design vehicles capable of reaching hypersonic speeds has become a necessity to satisfy industry requirements, hence requiring the need for better understanding of creep behavior of materials. Although the steady state creep of metals has been analyzed rigorously, there is little known about transient creep of many metals. Understanding transient creep behavior of metals is crucial in analysis and design of short term hypersonic flight applications. Hence, a transient creep analysis of 304SS, Al7075-T6, Al2024-T6, Inconel 625, Inconel 718, and Rene N4 is carried out focusing on the microstructural behavior of these metals undergoing high temperature operating conditions. In doing so, the material properties that were unknown in literature were determined by parameter fitting techniques using existing steady state experimental data and also previous parametric studies determining critical parameters affecting strain values. A transient creep deformation map for each metal is produced including the required design space of the application.

Committee: Mitch Wolff Ph.D. (Committee Chair); Anthony Palazotto Ph.D. (Advisor); Amir Farajian Ph.D. (Committee Member) Subjects: Aerospace Engineering; Aerospace Materials; Engineering; Materials Science; Mechanical Engineering

Master of Science (MS), Wright State University, 2015, Biological Sciences

Despite the clear advantages of generalist feeding, many insect herbivores feed on a relatively small number of available host plants with in phylogenetically restricted groups. To better understand patterns of host plant use I used the sister species Altinote stratonice and Altinote dicaeus and their overlapping but distinct host plant range. I measured physiological effects of plants by using development time, pupal mass, and survival. To determine the importance of enemies I quantified rates of parasitism and rates of predation. Finally I measured host plant frequency, and host plant abundance. I found that survival of A. dicaeus and A. stratonice was reduced on low quality host plants. Additionally host plant use by A. stratonice was correlated with host plant abundance and host plant use by A. dicaeus was correlated host plant size. Overall patterns of host plant use appeared to be driven by bottom up forces even when enemies present a clear threat.

Committee: John Stireman III Ph.D. (Advisor); Thomas Rooney Ph.D. (Committee Member); Don Cipollini Ph.D. (Committee Member) Subjects: Biology; Ecology; Entomology

MS, University of Cincinnati, 2009, Engineering : Computer Engineering

Data Tagging Systems are prevalent in all spheres of activity. Most of these systems are implemented using the RFID technique. In this thesis, we present an alternative approach to the problem of target identification/verification, namely the Optical Identification (OPID). The OPID system is a wireless identification system whereby communication takes place between the target and the interrogator through optical signals. The system consists of an optical data tag, which is the target, and an optical reader module which interrogates the tag and identifies it. This thesis is concerned with the design and development of the optical reader module.The design of the optical reader module is carried out with the objective of keeping the system compact and cost-effective. The range of operation is also flexible, with the maximum read distance of the prototype going up to 4 meters. The optical reader module can be classified into three important sub-modules. The first one is the photodetector coupled with the amplifier circuitry to convert the optical signal to electrical signal, the second is the analog to digital converter and the last one being the digital signal processing module. The decisions taken and the trade-offs at each stage of the design process are presented with the requisite validation. A working prototype of the optical receiver module is developed using discrete components and is laid out on a 3.8” X 2.5” printed circuit board and its performance is analyzed. The protocol for communication between the data tag and the optical reader is then explained in detail. This system provides an additional layer of security by implementing Bi-Phase Manchester encoding technique for data encryption. The data rate achieved using this technique is reasonable.

Committee: Dr. Fred R. Beyette Jr. PhD (Committee Chair); Dr. Philip A. Wilsey PhD (Committee Member); Dr. Jason C. Heikenfeld PhD (Committee Member) Subjects: Design; Electrical Engineering; Engineering; Optics

MS, University of Cincinnati, 2006, Engineering : Computer Engineering

Currently radio frequencies are employed in wireless internet and cellular telephones. Radio frequencies, however, are partially regulated and can interfere with surrounding devices. In contrast, optical communication offers a non-regulated/cost-effective interface that can be implemented with human safe light sources such as LEDs. Furthermore, the combination of imaging with optical communication makes communication with multiple optical data sources within a scene possible. This thesis explores the design of data communicating imaging sensors that store video and data information from a scene within an array of light sensitive pixels. Applications of these sensors include: security monitoring, optical-based asset tracking, or vehicle-to-vehicle communication. Four data communicating sensor designs are explored, concluding with two key designs: Beta and Gamma. The Beta sensor stores video and data within each pixel. The Gamma sensor stores video in every pixel but distributes data storage among a cluster of pixels.

Committee: Dr. Philip Wilsey (Advisor) Subjects:

Doctor of Philosophy, The Ohio State University, 2008, Electrical and Computer Engineering

This dissertation addresses two important research topics related to wideband beam-steering arrays with optical true time delay (TTD). The first topic presents the feasibility of using large-mode-area (LMA) photonic crystal fibers (PCF) as delay elements in White cell (WC) TTD to produce long-delays (0.2-20ns). The measured coupling loss from free-space into LMA-PCF is -2.15dB. However, it is shown in simulation that the loss decreases to -0.5dB by using additional field lenses. The measured and simulated data also show that LMA-PCF is not that sensitive to misalignments. Therefore, LMA-PCF is the most efficient delay element for a WC-TTD engine in terms of loss and volume minimization. The second topic is the demonstration of beam-steering in a wideband array with WC produced delays. A Quadratic WC was designed and simulated to produce four simultaneous delays (with Δt=25ps) for a four-sub-array system (for frequencies 2-18GHz) where each sub-array consists of two Vivaldi antennas. Simulation results show that aberrations in the long-delays generated with a lens-train suffer from a 3.2dB higher loss than that produced in free-space. Therefore, a Quartic cell is proposed with commercially available optics which does not use any glass blocks (for short-delays) or lens-trains (for long-delays) as delay elements. A proof-of-concept MEMS-based Quadratic cell was designed and aligned with optics available at ESL for Δt=500ps. The measured aberrated beams incident on the MEMS were 37.5μm, which is larger than the expected beamsize of 25μm. This caused a -10.6dB cross-talk between the null and the short-delay arms. A parametric study conducted of an ideal four-sub-array system formed by isotropic radiators showed that it can scan ±50° with Δt=25ps and 4° error in the beam-direction. Next, a four-sub-arrayed Vivaldi-array was built, the measured scattering matrix of it shows severe mutual coupling at low frequencies (2-5GHz). However, the array performs as expected in the r (open full item for complete abstract)

Committee: Roberto Rojas Prof (Advisor); Mohammed Ismail Prof (Committee Member); Fernando Teixeira Prof (Committee Member) Subjects: Electrical Engineering; Optics

Master of Arts (MA), Ohio University, 2008, Geography (Arts and Sciences)

Public space issues have long been discussed in the context of urban settings by geographers. As emancipatory spaces, places like plazas and squares have traditionally served as (potential) stages for the people's voice. Missing from this discussion is treatment of the US college campus and its potential as a space for transformation and politics. The College Green at Ohio University has a long tradition as a social/political forum for the university community, but yet in recent years has been circumscribed by the administration's speech zoning policies. This thesis examines the history of College Green as a contested space and as a place for politics and outlines the different changes in University policy affecting the Green as a stage for social and political interactions from the early 1960s to the post-Kent State era to the present. It is therefore a good case study for the examination of public space/forum on the college campus and a window into discussions about the role of the university in US society.

Committee: Harold A. Perkins PhD (Advisor); Risa Whitson PhD (Committee Member); Brad Jokisch PhD (Committee Member) Subjects: Geography

Master of Science (MS), Ohio University, 1995, Mechanical Engineering (Engineering)

A comparative study of the workspace and kinematics analysis for free-floating robots

Committee: S. Agrawal (Advisor) Subjects: Engineering, Mechanical

Doctor of Engineering, Cleveland State University, 2011, Fenn College of Engineering

This research demonstrates the feasibility of utilizing high intensity laser power beaming (HILPB) systems as a conduit for robust free-space optical communications over large distances and in challenging atmospheric conditions. The uniqueness of vertical multi-junction (VMJ) photovoltaic cells used in HILPB systems in their ability to receive and to convert at high efficiency, very high intensity laser light of over 200 W/cm2, presents a unique opportunity for the development of the robust free space optical communication system by modulating information signals onto the transmitted high intensity photonic energy. Experiments were conducted to investigate and validate several optical communications concepts. A laser modulator was implemented to exhibit the excellent transient response of the VMJ technology at very high illumination intensities, and thus show its applicability to optical communications. In addition, beam polarization optic stages were employed to demonstrate a secure multi-channel communications scheme. The off-axis response of the receiver and the beam profile were characterized in order to evaluate the feasibility of developing acceptable pointing and tracking geometries. Finally, the impact of signal modulation on the total converted energy was evaluated and shown to have minimal effect on the overall power transmission efficiency. Other aspects of the proposed communication system are studied including: quantifying beamwidth and directivity, signal-to-noise-ratio, information bandwidth, privacy, modulation and detection schemes, transmission channel attenuation and disturbances (atmospheric turbulence, scintillation from index of refraction fluctuations, absorption and scattering from thermal and moisture variation) and beam acquisition tracking and pointing influence on the performance metrics of optical transmission technologies. The result of this research demonstrates the feasibility of, and serves as a comprehensive design guide for the i (open full item for complete abstract)

Committee: Taysir Nayfeh PhD (Advisor); Nigamanth Sridhar PhD (Committee Member); Petru Fodor PhD (Committee Member); John Turner PhD (Committee Member); Ana Stankovic PhD (Committee Member); Joseph Svestka PhD (Other) Subjects: Communication; Electrical Engineering; Engineering; Experiments; Optics

Master of Science (MS), Ohio University, 2013, Athletic Training (Health Sciences and Professions)

Introduction: The World Health Organization's International Classification of Functioning, Disability, and Health (WHO ICF) defines function as the interaction between body function and activity within the social environment. Current outcome measures fail to assess physical activity within free-living environments. Measuring physical activity within free-living environments may be a more accurate measure of function. The Movement and Activity in Physical Space (MAPS) System has been developed and validated as an objective functional outcome measure that combines physical activity data with free-living environmental interactions.3 An accelerometer records acceleration and steps and global positioning system (GPS) device measures environmental interactions.1-3 These data are then combined to produce raw scores that represent function using the MAPS formula. Purpose: The primary purpose of this study was to further develop and validate the MAPS system as an objective functional outcome measure following anterior cruciate ligament (ACL) reconstruction surgery. The secondary purpose of this study was to determine if MAPS scores are sensitive to change throughout the recovery process. Methods: An observational and longitudinal study was designed. A total of 8 participants completed 4 data collection sessions following ACL surgery (n = 8, mean ± SD; age, 19.71 ± 1.98y; height, 177.44 ± 6.12cm; weight, 83.12 ± 12.44kg). Physical activity data (accelerometer) and geospatial locations (GPS) were analyzed for each day of data collection. Results: Person product correlation showed little to no correlation between the KOOS and PROMIS assessments when compared to MAPS scores. MAPSAC and MAPSS scores observed a 445% and 513% percent change from SI + 1-10 and SI + 36-40, respectively. Dependent t-test comparing SI + 1-10 to SI + 36-40 showed that the MAPS scores were statistically different over time. Conclusion: The MAPS System has been developed to measure physical activity withi (open full item for complete abstract)

Committee: Brian Ragan PhD (Advisor); Chad Starkey PhD (Committee Member); Cheryl Howe PhD (Committee Member); Shannon David MS (Committee Member) Subjects: Physical Therapy; Sports Medicine