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Theoretical Analysis Of Charge Conduction And Rectification In Self-Assembled-Monolayers In Molecular Junctions, Francis Adoah Aug 2023

Theoretical Analysis Of Charge Conduction And Rectification In Self-Assembled-Monolayers In Molecular Junctions, Francis Adoah

Electronic Theses and Dissertations, 2020-

As electrical devices shrink to the atomic scale, it is expected that Moore's law will soon be obsolete for semiconductor devices. In 1974, Avriam and Ratner predicted that organic devices could replace semiconductor technology, leading to extensive research on molecular-based organic devices. This dissertation delves into the theoretical frameworks used to examine the transport in molecular junctions and aims to enhance our comprehension of charge transport and conduction properties. The studies presented in this thesis illustrates that a molecule's alteration by just a single atom can change it from an insulator to a conductor, and also that, by fine-tuning the …


Distributed Optimization With Limited Communication In Networks With Adversaries, Iyanuoluwa Emiola Aug 2023

Distributed Optimization With Limited Communication In Networks With Adversaries, Iyanuoluwa Emiola

Electronic Theses and Dissertations, 2020-

We all hope for the best but sometimes, one must plan for ways of dealing with the worst-case scenarios, especially in a network with adversaries. This dissertation illustrates a detailed description of distributed optimization algorithms over a network of agents, in which some agents are adversarial. The model considered is such that adversarial agents act to subvert the objective of the network. The algorithms presented in this dissertation are solved via gradient-based distributed optimization algorithm and the effects of the adversarial agents on the convergence of the algorithm to the optimal solution are characterized. The analyses presented establish conditions under …


Towards Explainable Ai Using Attribution Methods And Image Segmentation, Garrett J. Rocks Jan 2023

Towards Explainable Ai Using Attribution Methods And Image Segmentation, Garrett J. Rocks

Honors Undergraduate Theses

With artificial intelligence (AI) becoming ubiquitous in a broad range of application domains, the opacity of deep learning models remains an obstacle to adaptation within safety-critical systems. Explainable AI (XAI) aims to build trust in AI systems by revealing important inner mechanisms of what has been treated as a black box by human users. This thesis specifically aims to improve the transparency and trustworthiness of deep learning algorithms by combining attribution methods with image segmentation methods. This thesis has the potential to improve the trust and acceptance of AI systems, leading to more responsible and ethical AI applications. An exploratory …


Examining Direct Load Control Within Demand Response Programs, Maria Bonina Zimath Jan 2023

Examining Direct Load Control Within Demand Response Programs, Maria Bonina Zimath

Honors Undergraduate Theses

The power system is a complex entity with unique plant designs, control systems, and market strategies. For many years, engineers have developed advanced technology to keep the grid efficient and balanced. With the rise of renewable sources, some new technology and programs must be developed to keep the quality of the power system. Unlike traditional power plants, renewable energy is highly dependent on environmental factors, such as sunlight and wind, meaning the generation depends on an unpredictable source of fuel. As the grid moves to more sustainable sources, the power market faces a growing challenge of less control over the …


Process Optimization And Characterization Of P-Type Copper Indium Oxide And Copper Chromium Oxide Transparent Conducting Thin Films And Its Applications, Fnu Sreeram Sundaresh Jan 2023

Process Optimization And Characterization Of P-Type Copper Indium Oxide And Copper Chromium Oxide Transparent Conducting Thin Films And Its Applications, Fnu Sreeram Sundaresh

Electronic Theses and Dissertations, 2020-

Transparent conducting oxides (TCO) are a unique class of compounds that combine the properties of being optically transparent but at the same time are electrically conductive. TCOs are used in a variety of applications such as transparent contacts for solar cells, electrochromic windows, low-e windows, optoelectronic devices, light-emitting diodes, optical displays, UV sensors, defrosting windows, etc. By controlling doping and by adjusting the donor/acceptor levels, the conductivity of TCOs can be tuned from insulating via semiconducting to conducting. Various properties of TCOs such as optical transparency, bandgap, and electrical conductivity can be controlled using the aforementioned process. This concept paved …


Ocean Vector Wind Measurement Potential From The Global Precipitation Measurement Mission Using A Combined Active And Passive Algorithm, Alamgir Hossan Jan 2023

Ocean Vector Wind Measurement Potential From The Global Precipitation Measurement Mission Using A Combined Active And Passive Algorithm, Alamgir Hossan

Electronic Theses and Dissertations, 2020-

Ocean surface vector wind (OVW) is an essential parameter for understanding the physics and dynamics of the ocean-atmosphere system, thereby improving weather forecasting and climate studies. Satellite scatterometers, synthetic aperture radars, and polarimetric microwave radiometers have provided almost global coverage of ocean surface vector wind for the last four decades. Nonetheless, a consistent and uninterrupted long-time data record with the capability of resolving sub-diurnal variability has remained a critical challenge over the years. The Global Precipitation Measurement Mission (GPM) is a satellite mission designed to provide space-based precipitation information on a global scale with complete diurnal sampling. This dissertation presents …


Adversarial Attacks, Coarse Robustness, And Dataless Neural Networks: Novel Techniques For Improved Classification And Combinatorial Optimization, Ismail Alkhouri Jan 2023

Adversarial Attacks, Coarse Robustness, And Dataless Neural Networks: Novel Techniques For Improved Classification And Combinatorial Optimization, Ismail Alkhouri

Electronic Theses and Dissertations, 2020-

Neural networks (NN) have become a central component in most machine learning systems. However, studies have shown that these models are not robust against adversarial attacks. As such, in this dissertation, we explore four directions. In the first direction, we investigate adversarial attacks on two hierarchical classification (HC) models: the Flat HC (FHC), and the Top-Down HC (TDHC). In particular, we formulate attacks against these models by using convex programming. Through experimental results, it is shown that FHCs are more robust than TDHCs. Second, we formalize a new notion of coarse robustness that is defined with respect to a specified …


Coalition Formation And Beamsteering Optimization For Directional Software-Defined Radios, Sayanta Seth Jan 2023

Coalition Formation And Beamsteering Optimization For Directional Software-Defined Radios, Sayanta Seth

Graduate Thesis and Dissertation 2023-2024

Dynamic Spectrum Access (DSA), also known as Dynamic Spectrum Management, is the method of utilizing a set of spectrum techniques in real time to provide the ability to share wireless channels between Primary (or licensed) users (PUs) and Secondary (or unlicensed) users (SUs). The system is so designed that under normal circumstances, the PUs always get priority, but DSA enables the SUs to use the licensed bands as long as they do not create any interference on the PUs. Hence, the goal of utilizing the spectrum more efficiently can be achieved. Though DSA has been researched extensively as a new …


Structural Transformations In Photo-Thermo-Refractive Glass For Hologram Recording, Roberto Alejandro Alvarez Aguirre Jan 2023

Structural Transformations In Photo-Thermo-Refractive Glass For Hologram Recording, Roberto Alejandro Alvarez Aguirre

Electronic Theses and Dissertations, 2020-

This dissertation focuses on the structural transformations in photo-thermo-refractive (PTR) glass that enable recording phase holograms for efficient transformation of optical beams and high resolution spectroscopy. PTR glass is a multicomponent silicate matrix doped with Ce, Ag, Sn and Sb. It is a holographic phase medium with the ability of permanent refractive index change after UV exposure and thermal development above 500°C due to the precipitation of a NaF crystalline phase. Electronic processes are studied by analyzing the structure of absorption and luminescence bands of PTR glass matrix and its dopants. We analyze the structural transformations in PTR glass from …


Active Photonic Integrated Devices And Circuits On Thin-Film Lithium Niobate Platform, Ehsan Ordouie Jan 2023

Active Photonic Integrated Devices And Circuits On Thin-Film Lithium Niobate Platform, Ehsan Ordouie

Electronic Theses and Dissertations, 2020-

This thesis delves into innovative active photonic integrated devices and circuits on the thin-film lithium niobate (TFLN) platform, focusing on their applications and potential future advancements. We introduce a new family of electrooptic modulators (EOMs), the Four-Phase Electrooptic Modulators (FEOMs), which are fabricated using the TFLN platform. These devices effectively mitigate bandwidth and dynamic-range constraints in optical communication systems by reducing dispersion penalties and common-mode noises. Their functionality is demonstrated in a photonic time-stretch system. A dual-polarization variant further exemplifies the mitigation of both dispersion penalties and common-mode noises in long-haul communication links, marking significant strides towards the practical implementation …


High-Efficieny Ultrafast Mid-Infrared Source For Strong Field Science, Fangjie Zhou Jan 2023

High-Efficieny Ultrafast Mid-Infrared Source For Strong Field Science, Fangjie Zhou

Electronic Theses and Dissertations, 2020-

The potential of high-energy sources within the mid-infrared region (3-8 μm) has garnered significant attention for diverse research and industrial applications. Millijoule pulses extending beyond 3 μm can facilitate the production of x-rays with photon energies in the keV range through high harmonic generation (HHG). These high-energy x-ray pulses enable the characterization of electron dynamics within molecules and condensed matter materials. Additionally, the atmospheric transmission window between 3-5 μm allows lasers within this spectral range to deliver energy efficiently to distant targets via optical filaments without divergence, highlighting promising prospects for defense applications. In contrast to laser amplifiers, which are …


Distributed Detection In Energy Harvesting Wireless Sensor Networks, Ghazaleh Ardeshiri Dec 2022

Distributed Detection In Energy Harvesting Wireless Sensor Networks, Ghazaleh Ardeshiri

Electronic Theses and Dissertations, 2020-

A conventional wireless sensor networks (WSN), consisting of sensors powered by nonrechargeable batteries, has a strictly limited lifetime. Energy harvesting (EH) from the environment is a promising solution to address the energy constraint problem in conventional WSNs, and to render these networks to self-sustainable networks with perpetual lifetimes. In EH-powered WSNs, where sensors are capable of harvesting and storing energy, power control is necessary to balance the rates of energy harvesting and energy consumption for data transmission. In addition, wireless communication channels change randomly in time due to fading. These together prompt the need for developing new power control strategies …


Data-Driven Power System Stability Analysis And Control, Jian Xie Dec 2022

Data-Driven Power System Stability Analysis And Control, Jian Xie

Electronic Theses and Dissertations, 2020-

In recent years, with the expansion of power system size, the increase of interconnection and the use of large-scale renewable energy, power system stability and safe operations have become more prominent, causing challenges to the normal operation of power grid. Traditional analysis rely on detailed models of the system. But for real power systems, the operating state of the system is variable, and the model-based analysis methods may not accurately reflect the real operating state of the system. Therefore, this dissertation is focused on data-driven stability analysis and control. First, a method for locating the oscillation source of multi-machine systems …


Development Of A Dual-Mode Cmos Microelectrode Array For The Simultaneous Study Of Electrochemical And Electrophysiological Activities Of The Brain, Geoffrey Mulberry Jan 2022

Development Of A Dual-Mode Cmos Microelectrode Array For The Simultaneous Study Of Electrochemical And Electrophysiological Activities Of The Brain, Geoffrey Mulberry

Electronic Theses and Dissertations, 2020-

Medical diagnostic devices are in high demand due to increasing cases of neurodegenerative diseases in the aging population and pandemic outbreaks in our increasingly connected global community. Devices capable of detecting the presence of a disease in its early stages can have dramatic impacts on how it can be treated or eliminated. High cost and limited accessibility to diagnostic tools are the main barriers preventing potential patients from receiving a timely disease diagnosis. This dissertation presents several devices that are aimed at providing higher quality medical diagnostics at a low cost. Brain function is commonly studied with systems detecting the …


Grid-Interactive Buildings: Modeling, Operations, And Security, Guanyu Tian Jan 2022

Grid-Interactive Buildings: Modeling, Operations, And Security, Guanyu Tian

Electronic Theses and Dissertations, 2020-

Smart grids and smart buildings are two highly interdependent energy infrastructure systems. Buildings rely on the grid to provide reliable power while their flexibility can also be utilized to enhance the reliability and efficiency of power system operations. The quantification of heating, ventilation, and air condition (HVAC) system flexibility is critical to the operations of both the grid and buildings in demand response (DR) programs. However, the flexibility quantification is challenging due to the non-linearity and non-convexity of thermal dynamics associated with HVAC components. This dissertation proposes a novel HVAC flexibility quantification method based on a semidefinite programming (SDP) formulation. …


Light Trapping Transparent Electrodes, Mengdi Sun Jan 2022

Light Trapping Transparent Electrodes, Mengdi Sun

Electronic Theses and Dissertations, 2020-

Transparent electrodes represent a critical component in a wide range of optoelectronic devices such as high-speed photodetectors and solar cells. Fundamentally, the presence of any conductive structures in the optical path leads to dissipation and reflection, which adversely affects device performance. Many different approaches have been attempted to minimize such shadowing losses, including the use of transparent conductive oxides (TCOs), metallic nanowire mesh grids, graphene-based contacts, and high-aspect ratio metallic wire arrays. In this dissertation I discuss a conceptually different approach to achieve transparent electrodes, which involves recapturing photons initially reflected by highly conductive electrode lines. To achieve this, light-redirecting …


The Proof Of Concept Of The Hurricane Imaging Radiometer: Hurricane Wind Speed And Rain Rate Retrievals, Jonathan Coto Jan 2022

The Proof Of Concept Of The Hurricane Imaging Radiometer: Hurricane Wind Speed And Rain Rate Retrievals, Jonathan Coto

Electronic Theses and Dissertations, 2020-

This dissertation presents the proof of concept for the Hurricane Imaging Radiometer (HIRAD), where remote sensing retrievals of the 2-dimensional wind and rain fields for several hurricanes are validated with independent measurements. A significant contribution of this dissertation is the development of a novel statistical calibration technique, whereby the HIRAD instrument is radiometrically calibrated, using modeled brightness temperatures (Tb) generated using a priori hurricane wind and rain fields that are statistically representative of the actual hurricane conditions at the time of the HIRAD brightness temperature measurements. For this calibration technique, the probability distribution function of the measured HIRAD Tb's is …


Mos2 Based Memristive Synapses For Neuromorphic Computing, Adithi Pandrahal Krishnaprasad Sharada Jan 2022

Mos2 Based Memristive Synapses For Neuromorphic Computing, Adithi Pandrahal Krishnaprasad Sharada

Electronic Theses and Dissertations, 2020-

Brain inspired computing enabled by memristors have gained prominence over the years due to its nano-scale footprint, reduced complexity for implementing synapses and neurons. Several demonstrations show two-dimensional (2D) materials as a promising platform for realization of robust and energy-efficient memristive synapses. Ideally, a synapse should exhibit low cycle-to-cycle (C-C) and device-to-device (D-D) variability along with high maximum /minimum conductance (Gmax/Gmin) ratio, linearity and symmetry in weight update for obtaining high learning accuracy in neural networks (NNs). However, the demonstration of neuromorphic circuits using conventional materials systems has been limited by high C-C and D-D variability and non-linearity in the …


Search Space Reduction Techniques For Solution Of Combinatorial Optimization Problems In Power System., Ranadhir Sarkar Jan 2022

Search Space Reduction Techniques For Solution Of Combinatorial Optimization Problems In Power System., Ranadhir Sarkar

Electronic Theses and Dissertations, 2020-

Power system is vulnerable to disastrous climate events due to sequential or successive equipment failure. In this dissertation, the problem of identifying the critical k-transmission lines that fail one after another in quick succession, and the distribution system restoration problem using tie-lines/sectionalizing switches formulated as a mixed-integer non-linear programming problem (MINLP) that determines load shed under various k-line removal scenarios are solved. These problems are combinatorial that have huge search space, and solution through enumeration is intractable for large power systems. For reduction of search space, the following mathematical tools are derived, (i) two power flow methods due to k-transmission …


Space-Time Photonics, Abbas Shiri Jan 2022

Space-Time Photonics, Abbas Shiri

Electronic Theses and Dissertations, 2020-

Many of the features of photonic devices, including some of the most ubiquitous components such as resonators and waveguides, are usually thought to be intrinsically dependent on their geometry and constitutive materials. As such, the behaviour of an optical field interacting with such devices is dictated by the boundary conditions imposed upon the field. For instance, the resonant wavelengths and linewidths of a planar cavity are expected to be set by the mirrors' reflectivity, cavity length, and refractive index. Henceforth, satisfying a longitudinal phase-matching condition allows for incident light to resonate with the cavity. As another example, consider the planar …


Reconfigurable Load-Modulated Power Amplifier For Energy- And Spectrum-Efficient Wireless Communications, Haifeng Lyu Jan 2022

Reconfigurable Load-Modulated Power Amplifier For Energy- And Spectrum-Efficient Wireless Communications, Haifeng Lyu

Electronic Theses and Dissertations, 2020-

With the increasing demand for faster date rates and extensive user connectivities, the complex modulation schemes and large-scaled arrays have been widely researched and employed in the modern wireless links e.g., 5G and beyond-5G systems. These pose major challenges to design the power amplifiers (PAs) to accommodate the system level evolution. As the critical part, the power amplifiers (PAs) dominate the output power, efficiency, linearity and reliability of the radio frequency (RF) transmitter. Consequently, the PA's capability of maintaining an efficient, linear and reliable signal amplification operation is essential to the communication systems. On the other hand, due to the …


4.74 Ghz Harmonically Operated Saw Device For Sensing Applications And Interrogation System, Michael Morales Otero Jan 2022

4.74 Ghz Harmonically Operated Saw Device For Sensing Applications And Interrogation System, Michael Morales Otero

Electronic Theses and Dissertations, 2020-

Surface acoustic wave (SAW) devices have provided solutions to many sensor applications. With the increasing use of the electromagnetic spectrum, the adoption of higher frequencies for new developments is becoming a necessity. SAW devices represent a solution for advancing many emerging sensor's needs given their inherent advantages such as: wireless operation, low cost, and ease of fabrication. However, the SAW technology has been typically limited to frequencies under 3 GHz due to size limitations, increased SAW losses, and the need of an interrogation system suitable for reading SAW sensors at higher frequencies. This dissertation presents the work done to push …


A Measurement System For Detection Of Intestinal Motility In Neonates By Monitoring Slow Wave Activity, Garett Goodale Jan 2022

A Measurement System For Detection Of Intestinal Motility In Neonates By Monitoring Slow Wave Activity, Garett Goodale

Electronic Theses and Dissertations, 2020-

Similar to how electrocardiographic waves are the pace making signals of the heart, slow waves are the pace making signals of the intestines. Slow waves are electrical signals in the intestines that determine the speed at which food can move through the intestine ensuring proper digestion and uptake of nutrients. It has been shown that slow waves can be measured in adults using non-invasive, surface electrodes. However, no study has investigated the measurements of slow waves in neonates, specifically pre-term neonates. Around 7% of pre-term neonates suffer from necrotizing enterocolitis (NEC) which is a condition that causes damage to the …


Development Of Holographic Phase Masks For Wavefront Shaping, Nafiseh Mohammadian Jan 2022

Development Of Holographic Phase Masks For Wavefront Shaping, Nafiseh Mohammadian

Electronic Theses and Dissertations, 2020-

This dissertation explores a new method for creating holographic phase masks (HPMs), which are phase transforming optical elements holographically recorded in photosensitive glass. This novel hologram recording method allows for the fast production of HPMs of any complexity, as opposed to the traditional multistep process, which includes the design and fabrication of a master phase mask operating in the UV region before the holographic recording step. We holographically recorded transmissive HPMs that are physically robust (they are recorded in a silicate glass volume), can handle tens of kilowatts of continuous wave (CW) laser power, are un-erasable, user defined, require no …


Light Guiding And Concentrating Using Self-Collimating Spatially-Variant Photonic Crystals, Chun Xia Jan 2022

Light Guiding And Concentrating Using Self-Collimating Spatially-Variant Photonic Crystals, Chun Xia

Electronic Theses and Dissertations, 2020-

Advances in integrated photonic devices require low loss, easy-to-integrate solutions for chip-to-chip and chip-to-fiber interfacing. Among the most common solutions are traditional lenses. However, circular lenses require additional mounting mechanisms to ensure proper alignment. Additionally, the beam routing functionality cannot be added to the traditional lenses unless they are combined with mirrors and operate in the reflection mode. In this dissertation, we investigate lens-embedded photonic crystals (LEPCs) as a solution to flat and multifunctional lenses. The concept is demonstrated by creating self-collimating lattices containing a gradient refractive index lens (GRIN-LEPC), a binary-shaped lens (B-LEPC), and a Fresnel-type binary-shaped lens (F-B-LEPC). …


Direct Laser Writing Below The Diffraction Limit By Exploring Multi-Pulse-Induced Physics, Boyang Zhou Jan 2022

Direct Laser Writing Below The Diffraction Limit By Exploring Multi-Pulse-Induced Physics, Boyang Zhou

Electronic Theses and Dissertations, 2020-

Ultrafast laser ablation has enabled high-precision processing of a wide range of materials including metals, semiconductors, dielectrics, and polymers. Several laser nanostructuring methods exist, including those based on optical near-fields, special material properties, surface plasmons, and multiphoton absorption (MPA). Among these methods, the MPA method has the potential for nanoscale direct laser writing by using a simple experimental setup. However, the understanding of the fundamental mechanism involved in the laser ablation process is still incomplete, and it remains challenging to obtain a feature size much smaller than the diffraction-limited spot size. The goal of this research is to understand how …


Integrated Electro-Optic, Microwave, And Nonlinear Photonic Devices On Thin-Film Lithium Niobate, Milad Gholipour Vazimali Jan 2022

Integrated Electro-Optic, Microwave, And Nonlinear Photonic Devices On Thin-Film Lithium Niobate, Milad Gholipour Vazimali

Electronic Theses and Dissertations, 2020-

Lithium niobate has numerous extraordinary features that make it useful for a wide range of applications, particularly in optics. The material's strong electro-optic effect and second-order nonlinearities are two prime examples with applications in optical modulation and wavelength conversion, respectively. The thin-film lithium niobate platform has revitalized the conventional applications of lithium niobate during the last decade. The platform is now one of the most actively investigated subdisciplines in integrated photonics. The waveguides on this innovative platform are high index contrast, resulting in a size reduction of more than 20 times and a bending radius decrease of about two orders …


Biomimetic Design, Modeling, And Adaptive Control Of Robotic Gripper For Optimal Grasping, Mushtaq Al-Mohammed Jan 2022

Biomimetic Design, Modeling, And Adaptive Control Of Robotic Gripper For Optimal Grasping, Mushtaq Al-Mohammed

Electronic Theses and Dissertations, 2020-

Grasping is an essential skill for almost every assistive robot. Variations in shape and/or weight of different objects involved in Activities of Daily Living (ADL) lead to complications, especially, when the robot is trying to grip novel objects for which it has no prior information –too much force will deform or crush the object while too little force will lead to slipping and possibly dropped objects. Thus, successful grasping requires the gripper to immobilize an object with the minimal force. In Chapter 2, we present the design, analysis, and experimental implementation of an adaptive control to facilitate 1-click grasping of …


Multi-Element Mobile Optical Wireless Communication Networks, Pooya Nabavi Jan 2022

Multi-Element Mobile Optical Wireless Communication Networks, Pooya Nabavi

Electronic Theses and Dissertations, 2020-

The capacity of traditional wireless radio-frequency (RF) networks such as wireless fidelity (Wi-Fi) is insufficient to meet ever-increasing demand for bandwidth stemming from growth in smart, connected devices. The omni-directional nature of RF signals does not allow easy solutions that involve adding more access points to support more devices and capacity because they start to interfere with each other. Optical wireless communications (OWC) have already extended the superb bandwidth capacity of wired optical datalinks to sites that cannot be connected by traditional optical fibers, such as satellites and disaster recovery areas. Development of OWC technologies for dense, multi-user environments promises …


Synthesis And Characterization Of P-Type Transparent Conducting Copper Gallium Oxide Thin Films, Ashwin Kumar Saikumar Jan 2022

Synthesis And Characterization Of P-Type Transparent Conducting Copper Gallium Oxide Thin Films, Ashwin Kumar Saikumar

Electronic Theses and Dissertations, 2020-

Transparent conducting oxides (TCO) are a special class of materials that possess both the properties of optical transparency and electrical conductivity. They find use in various applications such as flat panel displays, light-emitting diodes, solar cells, touch screens, smart windows, etc. Some of the most well-known and widely used TCOs are ZnO doped with Al, In2O3 doped with Sn, and SnO2 doped with F. All these TCOs are n-type in nature and show n-type conductivity. On the contrary, p-type TCOs are not very common, and due to their inherent low mobility, it is very challenging to synthesize highly conductive p-type …