Publications (19)
Hybrid Reinforcement Learning and Model Predictive Control for Adaptive Control of Hydrogen-Diesel Dual-Fuel Combustion
Julian Bedei, Murray McBain, Alexander Winkler +3
Reinforcement Learning (RL) and Machine Learning Integrated Model Predictive Control (ML-MPC) are promising approaches for optimizing hydrogen-diesel dual-fuel engine control, as t…
Robust 1-norm periodograms for analysis of noisy non-Gaussian time series with irregular cadences: Application to VLBI astrometry of quasars
Valeri V. Makarov, Sébastien Lambert, Phil Cigan +2
Astronomical time series often have non-uniform sampling in time, or irregular cadences, with long gaps separating clusters of observations. Some of these data sets are also explic…
The K-band (24 GHz) Celestial Reference Frame determined from Very Long Baseline Interferometry sessions conducted over the past 20 years
Hana Krasna, David Gordon, Aletha de Witt +1
The third realization of the International Celestial Reference Frame (ICRF3) was adopted in August 2018 and includes positions of extragalactic objects at three frequencies: 8.4 GH…
AKIBoards: A Structure-Following Multiagent System for Predicting Acute Kidney Injury
David Gordon, Panayiotis Petousis, Susanne B. Nicholas +1
Diagnostic reasoning entails a physician's local (mental) model based on an assumed or known shared perspective (global model) to explain patient observations with evidence assigne…
Automated Dynamic Bayesian Networks for Predicting Acute Kidney Injury Before Onset
David Gordon, Panayiotis Petousis, Anders O. Garlid +4
Several algorithms for learning the structure of dynamic Bayesian networks (DBNs) require an a priori ordering of variables, which influences the determined graph topology. However…
Precise geodesy with the Very Long Baseline Array
Leonid Petrov, David Gordon, John Gipson +5
We report on a program of geodetic measurements between 1994 and 2007 which used the Very Long Baseline Array and up to 10 globally distributed antennas. One of the goals of this p…
Partial Alignment of Astrometric Position Excursions of International Celestial Reference Frame Quasars with Radio Jet Structures
Valeri V. Makarov, Phil Cigan, David Gordon +3
Published analyses of very long baseline interferometry (VLBI) data for the sources included in the third International Celestial Reference Frame (ICRF3) catalog have revealed obje…
The Celestial Reference Frame at K Band: The CRF-K-2025 Catalog
David Gordon, Aletha de Witt, Christopher S. Jacobs +10
We present an updated K band (24 GHz) celestial reference frame (CRF) constructed from 3.5 million Very Long Baseline Interferometry (VLBI) observations collected during 211 observ…
Testing Causal Explanations: A Case Study for Understanding the Effect of Interventions on Chronic Kidney Disease
Panayiotis Petousis, David Gordon, Susanne B. Nicholas +1
Randomized controlled trials (RCTs) are the standard for evaluating the effectiveness of clinical interventions. To address the limitations of RCTs on real-world populations, we de…
Safe Reinforcement Learning-based Control for Hydrogen Diesel Dual-Fuel Engines
Vasu Sharma, Alexander Winkler, Armin Norouzi +3
The urgent energy transition requirements towards a sustainable future stretch across various industries and are a significant challenge facing humanity. Hydrogen promises a clean,…
On More than Two Decades of Celestial Reference Frame VLBI Observations in the Deep South: IVS-CRDS (1995-2021)
S. Weston, A. de Witt, Hana Krasna +13
The International VLBI Service for Geodesy & Astrometry (IVS) regularly provides high-quality data to produce Earth Orientation Parameters (EOP), and for the maintenance and realiz…
Deep Learning based Model Predictive Control for Compression Ignition Engines
Armin Norouzi, Saeid Shahpouri, David Gordon +6
Machine learning (ML) and a nonlinear model predictive controller (NMPC) are used in this paper to minimize the emissions and fuel consumption of a compression ignition engine. In…
Imaging Sources in the Third Realization of the International Celestial Reference Frame
Lucas R. Hunt, Megan C. Johnson, Phillip J. Cigan +2
The third iteration of the International Celestial Reference Frame (ICRF3) is made up of 4536 quasars observed at S/X bands using Very Long baseline Interferometry (VLBI). These so…
The Next Generation Celestial Reference Frame
Megan Johnson, Frank Schinzel, Jeremy Darling +10
Astrometry, the measurement of positions and motions of the stars, is one of the oldest disciplines in Astronomy, extending back at least as far as Hipparchus' discovery of the pre…
Machine Learning Integrated with Model Predictive Control for Imitative Optimal Control of Compression Ignition Engines
Armin Norouzi, Saeid Shahpouri, David Gordon +6
The high thermal efficiency and reliability of the compression-ignition engine makes it the first choice for many applications. For this to continue, a reduction of the pollutant e…
The Myths of Our Time: Fake News
VÃt RůžiÄka, Eunsu Kang, David Gordon +3
While the purpose of most fake news is misinformation and political propaganda, our team sees it as a new type of myth that is created by people in the age of internet identities a…
Incorporating a Deep Neural Network into Moving Horizon Estimation for Embedded Thermal Torque Derating of an Electric Machine
Alexander Winkler, Pranav Shah, Katrin Baumgärtner +3
This study presents a novel state estimation approach integrating Deep Neural Networks (DNNs) into Moving Horizon Estimation (MHE). This is a shift from using traditional physics-b…
Position and Proper Motion of Sagittarius A* in the ICRF3 Frame from VLBI Absolute Astrometry
David Gordon, Aletha de Witt, Christopher S. Jacobs
Sagittarius A* (Sgr A*) is a strong, compact radio source believed to be powered by a super-massive black hole at the galactic center. Extinction by dust and gas in the galactic pl…
Metrics of Astrometric Variability in the International Celestial Reference Frame: I. Statistical analysis and selection of the most variable sources
Phil Cigan, Valeri Makarov, Nathan Secrest +3
Using very long baseline interferometry data for the sources that comprise the third International Celestial Reference Frame (ICRF3), we examine the quality of the formal source po…