Digital Commons Network^™

A Hybrid Model-Based Data-Driven Framework For The Electromagnetic Near-Field Scanning, Yanming Zhang, Lijun Jiang

Electrical and Computer Engineering Faculty Research & Creative Works

This article presents a novel hybrid approach for electromagnetic near-field scanning, combining model-based, i.e., Gaussian processes regression, and data-driven, i.e., dynamic mode decomposition, techniques. We first leverage the Latin hypercube sampling technique to achieve spatially sparse measurements. Subsequently, dynamic mode decomposition is applied to analyze the resulting spatiotemporal data with sparse spatial sampling, enabling the extraction of both frequency information and sparse dynamic modes. Finally, the Gaussian processes regression, also known as the Kriging method, is adopted for the full-state reconstruction. The proposed hybrid approach is benchmarked by an example of the crossed dipole antennas. The obtained results demonstrate that …

Empowering Urban Traffic Management: Elevated 3d Lidar For Data Collection And Advanced Object Detection Analysis, Nawfal Guefrachi, Hakim Ghazzai, Ahmad Alsharoa

Electrical and Computer Engineering Faculty Research & Creative Works

The 3D object detection capabilities in urban environments have been enormously improved by recent developments in Light Detection and Range (LiDAR) technology. This paper presents a novel framework that transforms the detection and analysis of 3D objects in traffic scenarios by utilizing the power of elevated LiDAR sensors. We are presenting our methodology's remarkable capacity to collect complex 3D point cloud data, which allows us to accurately and in detail capture the dynamics of urban traffic. Due to the limitation in obtaining real-world traffic datasets, we utilize the simulator to generate 3D point cloud for specific scenarios. To support our …

Lifelong Learning-Based Optimal Trajectory Tracking Control Of Constrained Nonlinear Affine Systems Using Deep Neural Networks, Irfan Ganie, Sarangapani Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

This article presents a novel lifelong integral reinforcement learning (LIRL)-based optimal trajectory tracking scheme using the multilayer (MNN) or deep neural network (Deep NN) for the uncertain nonlinear continuous-time (CT) affine systems subject to state constraints. A critic MNN, which approximates the value function, and a second NN identifier are together used to generate the optimal control policies. The weights of the critic MNN are tuned online using a novel singular value decomposition (SVD)-based method, which can be extended to MNN with the N-hidden layers. Moreover, an online lifelong learning (LL) scheme is incorporated with the critic MNN to mitigate …

Impact Of Ai On The Hri Dynamic In Search And Rescue Operations Using Uav Swarms, Jordan Morrow, Maciej Jan Zawodniok, Anhar Sami Mohammed

Electrical and Computer Engineering Faculty Research & Creative Works

Artificial intelligence (AI) offers significant benefits in search and rescue applications by enhancing the efficiency and effectiveness of the search. However, an over-reliance on AI can hinder the operation due to biases embedded in the underlying algorithms. This partiality, if left un-monitored, can pose a risk to the safety of those in need of disaster relief. Typically manifests into inaccuracies in the decision-making processes and if not carefully monitored can cause larger issues. This paper extends the knowledge presented in a previous work, which presents the design and modeling of search and rescue operations using unmanned aerial vehicle (UAV) swarms. …

Deep Learning For Uav Detection And Classification Via Radio Frequency Signal Analysis, Prajoy Podder, Maciej Zawodniok, Sanjay Madria

Electrical and Computer Engineering Faculty Research & Creative Works

Unmanned Aerial Vehicles (UAVs) are advertised as great tool that benefits society and humanity. However, UAVs also pose significant security threats ranging from privacy invasions, to interfering with commercial aircraft landing and takeoff, to accidently crashing into vehicles or people, to military or terrorist attacks. Consequently, there is a pressing need to detect and identify UAVs to mitigate such potential risks. While image-based methods are crucial for UAV detection, radio frequency (RF) emissions offer additional valuable insights. Analyzing RF signals, such as those used in UAV-ground station communications, can provide information about UAV types based on distinct frequency usage or …

Frequency Division Multiplexing And Random Phasing For Improved Uniformity In Microwave Heating Applications, Logan M. Wilcox, Ali Mirala, Mohammad Tayeb Al Qaseer, Kristen M. Donnell

Electrical and Computer Engineering Faculty Research & Creative Works

Microwave heating has been recently used as an active thermal excitation method in thermography. Within the nondestructive testing and evaluation (NDT&E) realm, this method is referred to as active microwave thermography, or AMT. In AMT, unlike other thermal excitation methods utilized in thermography, microwave heating inherently provides a nonuniform heating pattern. This is a direct result of the radiating antenna used to deliver the energy. This nonuniform pattern may result in defect detection errors (i.e., false positives and/or negatives). To reduce this potential for detection error and improve the overall robustness of the technique, a new electromagnetic system, consisting of …

Additively Manufactured Aperture-Based Fss, Alexander Hook, Doyle T. Motes, Cody Morrow, Kristen M. Donnell

Electrical and Computer Engineering Faculty Research & Creative Works

Frequency selective surfaces (FSSs) are arrays of patch- or aperture-based elements with specific high frequency reflective and/or transmissive properties. The specific FSS response of a given design is dictated by the element dimensions and spacing relative to adjacent elements (collectively referred to as the unit cell), along with the substrate (and superstrate if applicable) properties. As it relates to sensing, the FSS response may be affected by environmental (e.g., temperature) or structural (e.g., strain) changes. To this end, FSS-based sensors have been considered in recent years for a myriad of sensing applications including structural health monitoring (SHM). Concurrent to this, …

Angle-Dependent Photoinduced Changes Of Near-Infrared Transmission In Amorphous Selenium Films, Kaitlin Hellier, Emily Enlow, Seyedehnajmeh Montazeri, Mina Esmaeelpour, Shiva Abbaszadeh

Electrical and Computer Engineering Faculty Research & Creative Works

Amorphous selenium (a-Se) is a promising semiconductor for a variety of photoconductive applications, predominantly in X-ray detection. In addition, material properties introduce several other potential applications in nonlinear optics. Photodarkening (PD) presents an interesting area of study; when exposed to band-region light, metastable structural changes induce a shift in the band edge and increase tail absorption. In this work, we investigate these effects utilizing a near-infrared (NIR) probe to avoid generating any darkening during beam transmission. We observe an unexpected result; here, we present the effects of band region exposure in NIR transmission (1570 nm). We observe a shift from …

High-Sensitivity Fabry-Perot Interferometric Sensor Based On Microwave Photonics With Phase Demodulation, Ruimin Jie, Hongkun Zheng, Osamah Alsalman, Jie Huang, Chen Zhu

Electrical and Computer Engineering Faculty Research & Creative Works

Optical fiber sensors have emerged as vital tools in various applications. Among them, Fabry-Perot interferometers (FPIs), have gained prominence due to their compactness and versatility in sensor design. Microwave photonics (MWP) techniques offer enhanced performance and flexibility for developing optical sensor interrogation methods. This paper proposes and experimentally demonstrates a novel MWP interrogation technique based on phase measurement for short-cavity FPI sensors. The technique utilizes the phase response of the FPI sensor within an MWP-assisted single radio frequency bandpass filter, providing improved sensitivity and dynamic sensing capabilities compared to traditional methods. Simulation and experimental results validate the effectiveness of the …

Online Continual Safe Reinforcement Learning-Based Optimal Control Of Mobile Robot Formations, Irfan Ganie, S. Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

In this work, a leader-follower tracking and formation control strategy for mobile robots (MRs) with uncertain dynamics is proposed. This strategy utilizes a continual lifelong safe reinforcement learning (CLSRL) framework based on multilayer neural networks (MNNs). The proposed design employs actor-critic MNNs, incorporating a barrier function. This function is derived from the Bellman optimality principle. It addresses the state constraints throughout the control design process. A novel online continual lifelong learning (CLL) method is introduced for MR formation. This method leverages the Bellman residual error for weight significance in MNNs. It addresses catastrophic forgetting and interlayer dependence through layer-specific regularizers. …

Reinforcement Learning-Based Constrained Optimal Control Of Strict-Feedback Nonlinear Systems: Application To Autonomous Underwater Vehicles, Behzad Farzanegan, S. Jagannathan

Electrical and Computer Engineering Faculty Research & Creative Works

This paper addresses a constrained neural network (NN)-based optimal tracking scheme for a class of uncertain nonlinear discrete-time systems in strict-feedback form by using a control barrier function (CBF). First, a modified barrier-type cost function is introduced for each subsystem, guiding the actual system trajectory toward the safe set or desired trajectory while avoiding unwanted sets. To address the tracking problem, an augmented system is employed to convert the time-varying optimal tracking to a time-invariant optimal regulation. Then, an actor-critic framework is employed with the backstepping technique to obtain both virtual and actual optimal control policies for each subsystem to …

Highly Sensitive Liquid-Level Sensing Based On Microwave Frequency Domain Reflectometry And Interferometry, Chen Zhu, Osamah Alsalman, Jie Huang

Electrical and Computer Engineering Faculty Research & Creative Works

Frequency domain reflectometry (FDR) and interferometry are two widely used investigative techniques that have been instrumented using optical and microwave devices for a diverse array of sensing applications. In this paper, we present a highly sensitive liquid-level sensor using a custom hollow coaxial cable transmission line. Measurements of liquid levels with high sensitivity and resolution can be achieved by both FDR and interferometry-based measurements using the same sensor device. We show that FDR-based measurements are more straightforward for liquid-level sensing and are suitable for both small and large variations of liquid level, while interferometry-based measurements provide slightly higher measurement resolution …

Learning From The Past: Using Peer Data To Improve Course Recommendations In Personalized Education, Colton Walker, Sahra Sedigh Sarvestani, Ali R. Hurson

Electrical and Computer Engineering Faculty Research & Creative Works

This research introduces a recommendation system designed to enhance student success by intelligently personalizing the semester schedules and graduation path based on the student's performance, interests, and background; and inspired by the academic journeys of similar students who have successfully graduated in the past. The proposed recommender system leverages a combination of Markov decision processes, Q-Learning, and collaborative filtering techniques to identify graduation paths with a higher likelihood of success for the student. The proposed model is versatile and generic and can be adapted to various disciplines if sufficient past historical data is available. The proposed model has been prototyped …

Lidar From The Sky: Uav Integration And Fusion Techniques For Advanced Traffic Monitoring, Baya Cherif, Hakim Ghazzai, Ahmad Alsharoa

Electrical and Computer Engineering Faculty Research & Creative Works

Light detection and ranging (LiDAR) technology's expansion within the autonomous vehicles industry has rapidly motivated its application in numerous growing areas, such as smart cities, agriculture, and renewable energy. In this article, we propose an innovative approach for enhancing aerial traffic monitoring solutions through the application of LiDAR technology. The objective is to achieve precise and real-time object detection and tracking from aerial perspectives by integrating unmanned aerial vehicles with LiDAR sensors, thereby creating a potent Aerial LiDAR (A-LiD) solution for traffic monitoring. First, we develop a novel deep learning algorithm based on pointvoxel-region-based convolutional neural network (RCNN) to conduct …

Survey Of Hidden Markov Models (Hmms) For Sign Language Recognition (Slr), Iwan Sandjaja, Ahmad Alsharoa, Donald Wunsch, Jian Liu

Electrical and Computer Engineering Faculty Research & Creative Works

This paper surveyed several significant papers on specific topics applying the Hidden Markov Models (HMMs) for Sign Language Recognition (SLR), divided into five main episodes: Classical HMMs, Extended HMMs, HMMs and Machine Learning, HMMs and Sensor Fusion, and HMMs and Big Data. This stringent survey would contribute significantly to advanced research on unification brain models such as neural networks, adaptive resonance theory, and confabulation theory. First, the HMM was introduced as one of the popular methods of performing SLR, and each episode of its development was expounded. In each episode, a main paper and several supporting papers were summarized. Next, …

Effect Of Signal Modulation On Active Microwave Thermography, Logan M. Wilcox, Mathias Bonmarin, Kristen M. Donnell

Electrical and Computer Engineering Faculty Research & Creative Works

Active microwave thermography (AMT) is a coupled electromagnetic and thermographic nondestructive testing and evaluation (NDT&E) technique. AMT utilizes an active electromagnetic source to induce heat on or within a specimen under test (SUT) with subsequential infrared measurements via an infrared camera. AMT has been successfully employed in multiple fields, including aerospace, space, and infrastructure, among others. Generally, for AMT, the excitation (electromagnetic source) is applied over a specified period of time (referred to as the heating time). If inspection continues for additional time after the excitation is removed (turned off), this period is referred to as the cooling time. This …

Tightening Qc Relaxations Of Ac Optimal Power Flow Through Improved Linear Convex Envelopes, Mohammad Rasoul Narimani, Daniel K. Molzahn, Katherine R. Davis, Mariesa L. Crow

Electrical and Computer Engineering Faculty Research & Creative Works

AC optimal power flow (AC OPF) is a fundamental problem in power system operations. Accurately modeling the network physics via the AC power flow equations makes AC OPF a challenging nonconvex problem. To search for global optima, recent research has developed various convex relaxations that bound the optimal objective values of AC OPF problems. The QC relaxation convexifies the AC OPF problem by enclosing the non-convex terms within convex envelopes. The QC relaxation's accuracy strongly depends on the tightness of these envelopes. This paper proposes two improvements for tightening QC relaxations of OPF problems. We first consider a particular nonlinear …

Visualization Of Noise Coupling Paths Based On The Reciprocity Theorem, Seungtaek Jeong, Jong Hwa Kwon, Deepak Pai, Jagan Rajagopalan, Chulsoon Hwang

Electrical and Computer Engineering Faculty Research & Creative Works

In this article, visualization of noise coupling paths is proposed and verified. The coupling coefficient (CC) is derived based on the Reciprocity theorem and time-average coupled power, which represents the contribution of each spatial point to the coupled power. The physical meaning of CC is demonstrated by relating the integrations of CC in a volume space occupied by absorbers to the coupled power being suppressed by the absorbers. The proposed method is applied to a practical device and the identified dominant coupling paths are experimentally verified.

Tilted Fiber Bragg Grating Sensors Based On Time-Domain Measurements With Microwave Photonics, Shiyu Li, Ruimin Jie, Osamah Alsalman, Jie Huang, Chen Zhu

Electrical and Computer Engineering Faculty Research & Creative Works

Tilted fiber Bragg gratings (TFBGs) have garnered substantial research attention and have found widespread applications for sensing a diverse array of physical, chemical, and biological parameters based on optical spectrum measurements. The interrogation of a TFBG sensor typically requires a high-resolution bulky optical spectrum analyzer (OSA) due to the extremely narrow dips caused by the resonance of cladding modes. However, high-resolution OSAs can be costly and have limitations on measuring speed, limiting their practicality. In this paper, a new approach to interrogating TFBG sensors is proposed and experimentally demonstrated based on a microwave photonics technique. Instead of measuring the optical …

Simultaneous Frequency Regulation And Active Power Sharing In Islanded Microgrid Using Deep Reinforcement Learning, Oroghene Oboreh-Snapps, Sophia A. Strathman, Jonathan Saelens, Arnold Fernandes, Lauryn Morris, Praneeth Uddarraju, Jonathan W. Kimball

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents a novel approach that integrates deep reinforcement learning (DRL) with the conventional virtual synchronous generator (VSG) to address dual objectives of microgrid (MG) control, frequency regulation and precise active power sharing. MGs typically consist of multiple Inverter-Based-Distributed-Generators (IBDGs) connected in parallel through different line impedances. The conventional active power loop (APL) of the VSG encounters significant steady-state frequency errors as load increases/decreases during islanded operation. To mitigate this issue, secondary-level controllers like proportional-integral (PI) control are added to the APL to regulate the frequency of IBDGs. However, PI control compromises power-sharing capabilities when the impedance values of …

Quantifying Wild Pig Disturbance In Pastures And Wetlands Using Unmanned Aerial Vehicle-Derived Imagery, Wesley M. Anderson, Bethany Wight, Raoul K. Boughton

Human–Wildlife Interactions

The use of unmanned aerial vehicles (UAVs) for agricultural and environmental research has increased markedly in recent years, and a key application has been to conduct damage assessments. Invasive wild pigs (Sus scrofa) cause both agricultural and environmental damage, and past studies have utilized UAVs to quantify this damage. Each methodology has advantages, but they also have drawbacks such as high rates of damage omission or reliance upon a near-infrared camera, which may be prohibitively expensive for some land managers and scientists. Our objective was to develop a methodology that could be easily implemented to conduct wild pig …

Flashtags: Evaluating A Novel Deterrent To Reduce Livestock Depredation, C. Aaron Bott, Stewart W. Breck, Tom W. Murphy, Brad A. Freking, Carlos A. López González, David Prause, Corey Peavey, Albert Sommers, Coke Landers, Julie K. Young

Human–Wildlife Interactions

Social tolerance of carnivores can be improved by preventing conflicts through nonlethal predator deterrents (e.g., livestock protection dogs [Canis lupus familiaris] and human presence) that have been used for centuries. However, many livestock producers feel the existing preventative methods are inadequate for extensive production systems where livestock can be spread widely and have less human supervision. To address this issue, we developed and tested a new nonlethal tool called FlashTags to reduce livestock predation. FlashTags are ear tags worn by livestock that flash a random-light pattern at night when motion-triggered. In the first year, we tested the devices …

Waterbird-Perceived Damage, Control Measures, And Economic Implications For Rice Production In The Brazilian Cerrado, Demetrio Luis Guadagnin, Alexandre Afonso Meyer, João Augusto Rossi Borges, Fernanda Maia Justo

Human–Wildlife Interactions

Waterbirds have the potential to inflict economic damage to crops. However, is rice (Oryza sativa) production in the Brazilian Cerrado significantly affected by waterbirds? This study aimed to assess the extent of waterbird damage on irrigated rice production in Central Brazil. We conducted surveys of waterbird populations in rice agroecosystem habitats throughout the cultivation cycle and analyzed the expenses associated with waterbird-induced yield losses and the control measures employed by farmers. The 2 most prevalent waterbird species observed were Dendrocygna viduatta and D. autumnalis, comprising 68.6% of all recorded waterbirds. These species were more frequently encountered and …

Spatial Analysis Of Socioeconomic Factors At Found Locations Of Orphaned Mammals In Champaign County, Illinois, Usa, Colleen Elzinga, Stephanie Heniff, William Sander, William Marshall Brown, Csaba Varga, Samantha Sander

Human–Wildlife Interactions

Young mammals make up a significant portion of animals brought into wildlife rehabilitation centers. Unfortunately, some of these presumed orphaned individuals are inappropriately removed from their native habitat. As such, there is a need for educational community outreach centered on the proper identification of orphaned wildlife that benefit from human intervention, while maximizing limited resources of rehabilitation facilities. This study evaluated found locations of common mammalian orphans presenting from Champaign County to the University of Illinois Wildlife Medical Clinic, Illinois, USA, between 2015 and 2020. The found locations of the orphans (99 Virginia opossums [Didelphis virginiana], 80 common …

The Lawlessness Of Sackett V. Epa, William W. Buzbee

Georgetown Law Faculty Publications and Other Works

When the Supreme Court speaks on a disputed statutory interpretation question, its words and edicts undoubtedly are the final judicial word, binding lower courts and the executive branch. Its majority opinions are the law. But the Court’s opinions can nonetheless be assessed for how well they hew to fundamental elements of respect for the rule of law. In particular, law-respecting versus law-neglecting or lawless judicial work by the Court can be assessed in the statutory interpretation, regulatory, and separation of power realms against the following key criteria, which in turn are based on some basic rule of law tenets: analysis …

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 …

Cultural Property: “Progressive Property In Action”, J. Peter Byrne

Georgetown Law Faculty Publications and Other Works

Cultural property law fulfills many of the normative and jurisprudential goals of progressive property theory. Cultural property limits the normal prerogatives of owners in order to give legal substance to the interests of the public or of specially protected non-owners. It recognizes that preservation of and access to heritage resources advance public values such as cultural enrichment and community identity. The proliferation of cultural property laws and their acceptance by courts has occurred despite a resurgent property fundamentalism embraced by the Supreme Court. Thus, this Article seeks to explicate the category of cultural property, its fulfillment of progressive theory, and …

Large Constellations Of Small Satellites: The Good, The Bad, The Ugly, And The Illegal, David A. Koplow

Georgetown Law Faculty Publications and Other Works

The most exciting and far-reaching contemporary developments regarding human activities in outer space arise from the recent drastic reductions in the costs of building, launching, and operating satellites, and from the concomitant sudden emergence of large constellations of small, inexpensive, privately-owned spacecraft. These satellites--devoted to highly remunerative functions such as communications (bringing high-speed, affordable internet to underserved constituencies), remote sensing (facilitating land use planning, weather forecasting, and emergency search and rescue), and support for military operations (in Ukraine and elsewhere)--already number in the thousands and will soon reach the tens of thousands.

But in addition to generating billions of …

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 …

Computational And Experimental Modeling Of Particle Transport Inside Respiratory Pathways And Indoor Environments, Abir Malakar

Electronic Theses and Dissertations

This thesis aims to explore efficient drug delivery to clinical target sites along the human upper airway that strongly depends on variables associated with the delivery device and the drug formulation, e.g., the device plume angle, particle sizes of drug solution, drug delivery speed of the device, viscosity of the drug solution, delivery axis orientation, and the formulation density. In our investigation, we prioritize the nasopharynx, the primary site of initial viral infection, as the ideal target zone for drug delivery. We have used Large Eddy Simulation and Lagrangian techniques to replicate breathing at 15 L/min and quantify regional drug …