Digital Commons Network^™

Adaptive Critic Optimal Control Of An Uncertain Robot Manipulator With Applications, Ravi Prakash, Laxmidhar Behera, Sarangapani Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

Realistic manipulation tasks involve a prolonged sequence of motor skills in varying control environments consisting of uncertain robot dynamic models and end-effector payloads. To address these challenges, this article proposes an adaptive critic (AC)-based basis function neural network (BFNN) optimal controller. Using a single neural network (NN) with a basis function, the proposed optimal controller simultaneously learns task-related optimal cost function, robot internal dynamics, and optimal control law. This is achieved through the development of a novel BFNN tuning law using closed-loop system stability. Therefore, the proposed optimal controller provides real-time, implementable, cost-effective control solutions for practical robotic tasks. The …

Towards Explainability Of Dimension Reduction Plots Of Unsupervised Learning Model Outcomes, Tony E.Astuhuaman Davila, Daniel B. Hier, Tayo Obafemi-Ajayi

Electrical and Computer Engineering Faculty Research & Creative Works

Dimension reduction methods are used to visualize the output of unsupervised learning models when applied to complex data. These techniques improve interpretability by transforming a high-dimension space to a lower-dimension space (usually 2D or 3D). The results are typically viewed as 2D scatter plots, and class centroids may be added to increase interpretability. Although useful, the relationship of these class centroids to the underlying feature space remains opaque. The innovative aspect of this work is to create a strong link between the dimension-reduced space and the underlying high-dimension feature space by adding selected feature centroids to the 2D scatter plots. …

Evaluation Of Transfer Learning Models On Traumatic Brain Injury Severity Classification, Ngoc Do, Daniel B. Hier, Tayo Obafemi-Ajayi

Electrical and Computer Engineering Faculty Research & Creative Works

After traumatic brain injury (TBI), clinicians use the Glasgow Coma Scale (GCS) to classify patients by severity and radiologists use the Rotterdam score and the Marshall score to classify CT scans by severity. This work investigates a viable efficient low-cost transfer learning model to use MRI images to predict GCS, Rotterdam, and Marshall severity class after TBI. The enhanced transfer learning model architecture integrates multiple fine-tuning steps in which a few layers of the pre-trained model is unfrozen in each iteration so that the neural network is able to learn layer by layer further aspects of the image for better …

Mechanisms For Unwanted Magnetic Field Coupling To A Shielded Magnetic Near-Field Probe, Xin Yan, Wei Zhang, Sajjad Sadeghi, Mehdi Gholizadeh, David J. Pommerenke, Daryl G. Beetner

Electrical and Computer Engineering Faculty Research & Creative Works

Unwanted field coupling is a major concern when using magnetic near-field probes for high-frequency scanning. The unwanted coupling of the tangential electric field to a tangential magnetic field probe has been studied extensively. This article shows a second unwanted coupling mechanism: coupling from a vertical magnetic field. The standing wave of a shorted pure TEM microstrip in air is utilized to separate the magnetic and electric field coupling. Simulations show that the eddy currents induced within the probe by the vertical magnetic field couple inductively to the pickup loop if the layer stack up is not symmetric. The unwanted magnetic …

Virtual Inertia Scheduling (Vis) For Microgrids With Static And Dynamic Security Constraints, Buxin She, Fangxing Li, Jinning Wang, Hantao Cui, Xiaofei Wang, Rui Bo

Electrical and Computer Engineering Faculty Research & Creative Works

Microgrids feature a high penetration of inverter-interfaced distributed energy resources (DERs). The low inertia characteristic and fast dynamics of DERs pose challenges to conventional decoupled static economic operation and dynamic control design within microgrids. Hence, this paper proposed virtual inertia scheduling (VIS) for microgrids, aiming to ensure both economy and security. First, a unified framework for device-level control and grid-level operation is introduced, with VIS serving as a key application to address low inertia issues. VIS actively harnesses the controllability and flexibility of DERs to effectively manage microgrid inertia. It updates the conventional economic operation framework by incorporating the virtual …

Coupling-Informed Data-Driven Scheme For Joint Angle And Frequency Estimation In Uniform Linear Array With Mutual Coupling Present, Yanming Zhang, Wenchao Xu, A. Long Jin, Min Li, Peifeng Ma, Lijun Jiang, Steven Gao

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes a novel coupling-informed data-driven algorithm tailored for the concurrent estimation of frequency and angle within a uniform linear array (ULA), while addressing the complicating influence of mutual coupling. Leveraging the hybrid dynamic mode decomposition (DMD) methodology, termed as averaged DMD, we incorporate moving average techniques to achieve effective denoising. The averaged DMD further decomposes the received signal into eigenvalues and corresponding eigenvectors. The frequency information is derived from the eigenvalues and the corresponding eigenvectors represent the steering vectors of sources. Subsequently, mutual coupling is informed into the calibration of the steering vector for each source. Specifically, the …

Design Of The Tm010 Mode Cylindrical Cavity Resonator For Pcb Dielectric Characterization, Reza Asadi, Chaofeng Li, Seyedmehdi Mousavi, Seyed Moastafa Mousavi, Reza Vahdani, Xiaoning Ye, Donghyun Kim

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents the study of the TM₀₁₀ mode cylindrical resonator, which can be used for printed circuit board (PCB) material properties extraction, e.g., the dielectric constant (Dk) and the loss tangent (Df) extraction. The theoretical formulas of the resonance frequency and Q-factor of the resonator are presented. In real measurement, the TM₀₁₀ mode cylindrical cavity resonator needs to be excited by the probe. The study emphasizes the impact of probe orientation, location, and field distribution on the accuracy of material property extraction. The relationship between cavity dimensions and resonance frequency is explored, highlighting the influence of cavity …

A Tensor-Based Data-Driven Approach For Multidimensional Harmonic Retrieval And Its Application For Mimo Channel Sounding., Yanming Zhang, Wenchao Xu, A. Long Jin, Min Li, Ping Yuan, Lijun Jiang, Steven Gao

Electrical and Computer Engineering Faculty Research & Creative Works

In wireless channel sounding, accurately estimating multiple parameters within a multipath signal, such as azimuth, elevation, Doppler shift, and delay, necessitates addressing the challenges posed by the multidimensional harmonic retrieval (MHR) problem. To overcome these complexities, we propose a framework based on high-order dynamic mode decomposition (HODMD) that designed for robustly estimating frequencies of interest from high-dimensional sinusoidal signals, particularly in additive white Gaussian noise conditions. The HODMD approach, a hybrid algorithm amalgamating high-order singular value decomposition (HOSVD) and dynamic mode decomposition (DMD), operates by initially decomposing observed tensorial data into a core tensor and R mode matrices through HOSVD. …

Modeling Of Power Distrubition Network (Pdn) Noise Coupling Induced Clock Phase Noise, Zhekun Peng, Junyong Park, Chaofeng Li, Joey Stecher, Srinivas Venkataraman, Xu Wang, Granthana Rangaswamy, Donghyun Kim

Electrical and Computer Engineering Faculty Research & Creative Works

Phase noise analysis is important to clock design. Noise sources of spurs shown on the phase noise result are challenging to find out due to the unknown source locations and coupling mechanisms. Noise from power distribution network (PDN) is one of the most troublesome sources. A behavioral modeling methodology is proposed to simulate the clock phase noise induced by PDN noise coupling for two different mechanisms: PDN-to-clock additive coupling and PDN-to-PDN up-conversion modulation. The thermal noise and 1/f flicker noise are simplified to provide a straightforward view of spur level. The model can be applied to both single-ended clock and …

Cascading Of 2d And 3d Simulations Of Asic Substrate Interconnect Up To 100 Ghz, Zhekun Peng, Junyong Park, Sathvika Bandi, Santosh Pappu, Srinivas Venkataraman, Xu Wang, Granthana Ranzaswamy, Donghyun Kim

Electrical and Computer Engineering Faculty Research & Creative Works

A method of cascading 3D models and 2D models to model the full channel of ASIC package substrate interconnects is proposed, showing good match to full-wave results in S-parameter and TDR up to 100 GHz.

Characterization Of The Kansas River Alluvial Aquifer Using Towed Transient Electromagnetic Geophysical Method, Jonathon Daniel Voss

Masters Theses

"Forecasted urban development areas west of Kansas City, Kansas in the coming decades has caused an increase of research into water resources (Butler et al. 2022). A location of investigation has been the Kansas River Alluvial Aquifer (KRAA) for shallow ground water resources. To investigate the KRAA structure and grain texture, the towed transient electromagnetic system (tTEM) in conjunction with direct push electrical conductivity logs and lithology wells were used to investigate four locations between Lawrence and Manhattan, Kansas. In total, 110 line-kilometers of tTEM data was collected. The tTEM data collected were high quality and through inversions of the …

A Binary Integer Linear Programming Model For Optimizing Underground Stope Layout, Theophilus Mensah

Masters Theses

"Underground mine planning engineers face significant challenges when determining what geometry provides the most profitable and safe stope for extraction. Several techniques and optimization algorithms have been developed in recent years, but most fail to find optimal solutions because they are heuristic or LP-based without efficient geometric constraints. This thesis work proposes a two-dimensional binary linear programming (BILP) model for determining the optimal combination of blocks in a stope that maximizes the economic value of the layout of stopes for a sublevel deposit. The work draws from Queyranne and Wolsey’s (2017 & 2018) formulations of tight constraints for bounded up/down …

Validation Of Athlet With Purdue University Multi-Dimensional Integral Test Assembly (Puma) Test, Emin Fatih Ozdem

Masters Theses

"Following the Three Mile Island Unit 2 (TMI-2) disaster, the development of a diagnostic system for emergency situations in a nuclear power plant was identified as an essential research area to strengthen the safety of nuclear power plants. A real-time estimation system of vital safety parameters on the main side of a PWR (Pressurized Water Reactor) facility was investigated since precise post-event scenario estimations are thought to be a crucial component of the diagnostic system. The alarm system of the plant can detect an SB-LOCA (Small Break Loss-Of-Coolant-Accident), but there were a couple of potential long-term transient occurrences. The accident …

The Deep Bsde Method, Daniel Kovach

Masters Theses

"The curse of dimensionality is the non-linear growth in computing time as the dimension of a problem increases. Using the Deep Backwards Stochastic Differential Equation (Deep BSDE) method developed in [HJE18], I approximate the solution at an initial time to a one-dimensional diffusion equation. Although we only approximate a one-dimensional equation, this method extends well to higher dimensions because it overcomes the curse of dimensionality by evaluating the given partial differential equation along "random characteristics''. In addition to the implementation, I also present most of the mathematical theory needed to understand this method"-- Abstract, p. iii

High Strain Rate Analysis Of 3d Printed Concrete As Compared To Conventionally Cast Concrete, Weston Mcleod Thomsen

Masters Theses

"3D Printed Concrete (3DPC) is a developing method of construction that has advantages over conventional methods, including formwork reduction, complex geometry, and expedited construction. This technology has potential benefits for the military when considering the austere environments that forward operating bases are built in. This study aims to assess 3DPC applications in protective structures that protect critical assets from explosive blasts. These protective structures experience a high-strain rate response during blast loading of the structure, and the effects of this have yet to be analyzed in the literature concerning 3DPC. With the lack of prior research, the focus here will …

Open-Ended Hollow Coaxial Cable Resonance Sensing Via Permittivity Fluctuations For Applications To Exhaled Breath Health Monitoring, Peter Henry Holtmann

Masters Theses

"We report a pre-diagnostics breath analyzer based on the open-ended hollow coaxial cable resonator (OE-HCCR) to achieve real-time differentiation of healthy and compromised lung function through electromagnetic analysis of exhaled breath matter. A two-phase amplification scheme of electromagnetic signatures metered via the S11 phase curve offers high sensitivity to permittivity fluctuations in exposed airflow. The mathematical model of the breath analyzer is explained, followed by experimental validation of numerical findings from previous work. The collection of breath transient signals is performed through monitoring the reflected power magnitude and phase of the scattering parameter (S11) at the resonance frequency. Material fluctuations …

Investigation Of The Relationships Between Hydraulic, Physical, And Biological Soil Parameters At A Vineyard In Saint James, Missouri, Lyndsey Bennett

Masters Theses

"Soil is a living, dynamic system that performs vital functions such as crop production, organic matter decomposition, and the flow and transport of water. Given the pressures of food and in some locales water security, climate change, and sustainability, farmers, scientists, and other related specialists and stakeholders must have access to understandable soil health indicators as well as the soil hydraulic function parameters to maximize crop growth while maintaining soil health. Although biological and physical soil parameters are different, we aim to evaluate their relationship at the field scale. Hydraulic conductivity in the vadose zone may be especially important, as …

The Geodetic Strain Rates From Gnss In The North American-Carribean-Cocos Triple Junction In Guatemala And Implications For Seismic Hazard, Tanaya Kashyap

Masters Theses

"Geodetic velocity data are pivotal for deciphering seismic risks, providing initial constraints for crustal surface strain rates. Gaining an understanding of the 2D surface strain tensor across an entire area necessitates knowledge of the surface velocity field, yet geodetic data such as measurements from the Global Navigation Satellite System (GNSS) are dispersed across the Earth’s surface. In the current scope of study, we have employed various methodologies to estimate strain rates in Guatemala, utilizing GNSS velocity data and leveraging the open-source Python tool Strain_2D. Strain_2D facilitates the computation of strain rates through diverse methods applied to the same dataset and …

Cryptographic Algorithms, Cryptocurrencies, And A Predictive Model Of Bitcoin Value By Pls Regression, Paul Kenneth O'Connor

Masters Theses

"With the invention of Bitcoin in 2009, as a seemingly timed response to the ongoing financial crisis, the popularity of the cryptocurrency has since continued to grow. Just this year, the Security Exchange Commission approved Bitcoin for exchange traded funds, allowing major investment firms to begin product trading. With this approval, and during this very moment of writing, Bitcoin has entered a bull market and reached a record value of over 72,000 USD. In addition, the Bitcoin halving event in April of 2024 is expected to increase demand even further. It has been anticipated that Bitcoin and other cryptocurrencies will …

Computational Fluid Dynamics Analysis Of Thermal-Hydraulic Phenomena In Nuclear Reactor Systems, Mehedi Hasan Tusar

Masters Theses

"A computational analysis of thermal-hydraulic processes in nuclear reactor systems is performed, leveraging Computational Fluid Dynamics (CFD) to advance the design and ensure the safety of nuclear reactors. Divided into two primary sections, the initial part examines thermal-hydraulic behavior in the Replacement Research Reactor (RRR) operating at 20 megawatts and evaluates potential enhancements for the Missouri University of Science and Technology Reactor (MSTR) to operate at an increased capacity of 2 megawatts from the existing 0.2 megawatts. Detailed simulations reveal insights into flow characteristics, temperature distributions, and pressure drops, highlighting the effective use of realistic and porous media modeling techniques …

Protein Turnover Rate And Life History As An Explanation Of The Extreme Difference In Cost Of Biosynthesis In Cockroach Nymphs And Painted Lady Butterfly Larva, Kyara Nicole Holloway

Masters Theses

The cost of biosynthesis in painted lady caterpillars is far lower than that of a red runner cockroach. A promising explanation for this phenomenon is the protein turnover rate for the animal during biosynthesis and tissue maintenance. Previous research has shown that, per gram of body weight, the painted lady butterfly can synthesize a biomass using up to 15x less energy and resources than the cockroach, even under similar conditions. The resulting ratios, especially in respect to growth rate, show a wide disparity between species in such a manner that does support a protein synthesis and degradation rates as a …

Theoretical Modeling And Experimental Investigation Of Phase Selection During Rapid Solidification Of Alloys, Azeez Aremu Akinbo

Masters Theses

"A novel model, rooted in time-dependent nucleation theory, has been created to explore how rapid solidification affects the extended solubility in metal alloys. This model was used to forecast solubility concerning undercooling in multiple binary aluminum (Al) alloys, and its predictions for both eutectic and peritectic systems closely match experimental data. It was demonstrated that this developed model surpasses the T0 line method, which does not consider the kinetic aspects of nucleation. Furthermore, the model can be extended to ternary and multicomponent phases by assuming that the scarcest element or the slowest diffusing component restricts nucleation. Al-Cu and Al-Cr, vital …

Creditor Courts, Alexander Billy, Neel U. Sukhatme

Georgetown Law Faculty Publications and Other Works

One of the largest institutional creditors in the United States is perhaps the most unexpected: the criminal court system. Each year, creditor courts collect more than $15 billion in revenues from criminal defendants. These fees are the lifeblood of the modern criminal legal system.

In this Article, we shed new light on the legal and economic framework under which myriad stakeholders operate in these creditor courts. By analyzing new survey data from clerks of court and 102 contracts with debt collection agencies in Florida, we provide general insights how creditor courts distort incentives and teem with conflicts of interest. These …

Mandatory Anti-Bias Cle: A Serious Problem Deserves More Meaningful Response, Rima Sirota

Georgetown Law Faculty Publications and Other Works

This essay addresses the problematic convergence of two recent trends: (1) the expansion of jurisdictions requiring anti-bias training (ABT) as part of mandatory continuing legal education (CLE), and (2) the growing recognition among social scientists that such training, at least as currently practiced, is of limited effectiveness.

Forty-six American states require continuing legal education (CLE), and eleven of these states now require lawyer ABT as one facet of CLE requirements. I have previously criticized the mandatory CLE system because so little evidence supports the conclusion that it results in more competent lawyers. The central question tackled by this essay is …

Fears, Faith, And Facts In Environmental Law, William W. Buzbee

Georgetown Law Faculty Publications and Other Works

Environmental law has long been shaped by both the particular nature of environmental harms and by the actors and institutions that cause such harms or can address them. This nation’s environmental statutes remain far from perfect, and a comprehensive law tailored to the challenges of climate change is still elusive. Nonetheless, America’s environmental laws provide lofty, express protective purposes and findings about reasons for their enactment. They also clearly state health and environmental goals, provide tailored criteria for action, and utilize procedures and diverse regulatory tools that reflect nuanced choices.

But the news is far from good. Despite the ambitious …

Blinded By The Light: Resolving The Conflict Between Satellite Megaconstellations And Astronomy, David A. Koplow

Georgetown Law Faculty Publications and Other Works

The sudden emergence of large constellations of small satellites in low altitude orbits represents one of the most dramatic contemporary innovations in outer space. Promising low-cost, low-latency global communications and spectacular capacities for remote sensing of the Earth, these satellites will soon number in the tens of thousands, sponsored by diverse corporations and countries around the world. But this proliferation of spacecraft comes at a steep cost in unavoidable interference with ground-based astronomy: as the satellites overfly the observatories, they block the views of remote objects and phenomena, leaving obliterating white streaks on the collected imagery, and obscuring access to …

The Crime Of Aggression: Its Nature, The Leadership Clause, And The Paradox Of Immunity, David Luban

Georgetown Law Faculty Publications and Other Works

The paper, written for a research handbook, critically surveys some fundamental philosophical, historical, and doctrinal issues in the crime of aggression. The two introductory sections set the theoretical issues in the context of Russia’s invasion of Ukraine, and explain the origins of criminalizing aggression under the heading of “crimes against peace.” Section 3 explores an ambiguity between aggression as first use of force and aggression as unprovoked use of force, while section 4 discusses the doctrinal distinction between acts of aggression and wars of aggression.

Sections 5 and 6 turn to the theory of aggression. Section 5 examines modern versus …

Towards An Effective Merger Review Policy: A Defence Of Rebuttable Structural Presumptions, Filippo Lancieri, Tommaso Valletti

Georgetown Law Faculty Publications and Other Works

We discuss the design of an effective merger review policy for the 21st century. We argue that the practice of the past decades is inadequate and propose a move towards much stronger rebuttable structural presumptions. These presumptions establish that all mergers above certain thresholds are illegal unless the merging parties can prove that merger-specific efficiencies will be shared with consumers and yield tangible welfare gains. These presumptions are grounded on solid economics and also acknowledge the real-world limitations in enforcement resources and information asymmetries between companies and regulators. We outline how to establish such presumptions in practice, defending the implementation …

Towards Fda–Uspto Cooperation, John R. Thomas

Georgetown Law Faculty Publications and Other Works

The Food and Drug Administration (“FDA”) and U.S. Patent and Trademark Office (“USPTO”) play complementary roles in driving pharmaceutical innovation. Yet, for the most part, the agencies conduct their affairs without regard for one another. Recent calls for a “whole of government” approach to reduce this departmentalism have led to only modest initiatives. Collectively, the FDA and USPTO have announced mandates that they have no intention of enforcing; conducted cross- training in topics that their employees will most likely never use; and resisted proposed legislation that would formalize their relationship.

Current agency intransigence represents a lost opportunity to further the …

Loper Bright In A Larger Interpretive Perspective: Is This Justice Scalia’S Court Anymore?, Victoria Frances Nourse

Georgetown Law Faculty Publications and Other Works

Loper Bright Enterprises v. Raimondo has left administrative lawyers agog: Could the Supreme Court really reverse the “goliath” known as Chevron deference? For those who study the Court’s interpretive landscape more broadly, however, Chevron reversal may not be as unexpected as administrative lawyers believe. This Article will look at Loper Bright by linking three notable interpretive developments: the major questions doctrine, Chevron skepticism, and strict constructions of statutory text. These developments share the same risk: the Court is imposing a new “clarity tax” on both Congress and administrative agencies. Having said this, others’ grave worries about changes in Chevron are …