Publications
Information Aware max-norm Dirichlet networks for predictive uncertainty estimation
Summary
Summary
Precise estimation of uncertainty in predictions for AI systems is a critical factor in ensuring trust and safety. Deep neural networks trained with a conventional method are prone to over-confident predictions. In contrast to Bayesian neural networks that learn approximate distributions on weights to infer prediction confidence, we propose a...
Ablation analysis to select wearable sensors for classifying standing, walking, and running
Summary
Summary
The field of human activity recognition (HAR) often utilizes wearable sensors and machine learning techniques in order to identify the actions of the subject. This paper considers the activity recognition of walking and running while using a support vector machine (SVM) that was trained on principal components derived from wearable...
NASA Airspace Integration Detect and Avoid Phase 2: Safety Risk Management Simulation Plan
Summary
Summary
RTCA has been developing Minimum Operational Performance Standards (MOPS) for Detect and Avoid (DAA) and Command and Control (C2) systems as part of Special Committee – 228 (SC-228). The Phase 1 MOPS were published in 2017 and a Phase 2 effort to revise and extend the Phase 1 MOPS is...
Operation of an optical atomic clock with a Brillouin laser subsystem
Summary
Summary
Microwave atomic clocks have traditionally served as the 'gold standard' for precision measurements of time and frequency. However, over the past decade, optical atomic clocks have surpassed the precision of their microwave counterparts by two orders of magnitude or more. Extant optical clocks occupy volumes of more than one cubic...
Adaptive stress testing: finding likely failure events with reinforcement learning
Summary
Summary
Finding the most likely path to a set of failure states is important to the analysis of safety critical systems that operate over a sequence of time steps, such as aircraft collision avoidance systems and autonomous cars. In many applications such as autonomous driving, failures cannot be completely eliminated due...
Ultrasound diagnosis of COVID-19: robustness and explainability
Summary
Summary
Diagnosis of COVID-19 at point of care is vital to the containment of the global pandemic. Point of care ultrasound (POCUS) provides rapid imagery of lungs to detect COVID-19 in patients in a repeatable and cost effective way. Previous work has used public datasets of POCUS videos to train an...
Ankle torque estimation during locomotion from surface electromyography and accelerometry
Summary
Summary
Estimations of human joint torques can provide quantitative, clinically valuable information to inform patient care, plan therapy, and assess the design of wearable robotic devices. Standard methods for estimating joint torques are limited to laboratory or clinical settings since they require expensive equipment to measure joint kinematics and ground reaction...
Ultrasound and artificial intelligence
Summary
Summary
Compared to other major medical imaging modalities such as X-ray, computed tomography (CT), and magnetic resonance imaging, medical ultrasound (US) has unique attributes that make it the preferred modality for many clinical applications. In particular, US is nonionizing, portable, and provides real-time imaging, with adequate spatial and depth resolution to...
A quantitatively derived NMAC analog for smaller unmanned aircraft systems based on unmitigated collision risk
Summary
Summary
The capability to avoid other air traffic is a fundamental component of the layered conflict management system to ensure safe and efficient operations in the National Airspace System. The evaluation of systems designed to mitigate the risk of midair collisions of manned aircraft are based on large-scale modeling and simulation...
High quality of service in future electrical energy systems: a new time-domain approach
Summary
Summary
In this paper we study dynamical distortion problems in future electrical energy systems with high renewable penetration. We introduce a new time-domain modeling of electrical energy systems comprising inverter-controlled distributed energy resources (DERs). This modeling is first used to quantify the relations between distortions and real/reactive power dynamics. Next, to...