Abstract
Active learning (AL) is a Machine Learning (ML) strategy that offers a promising solution to challenges posed by the data-intensive tasks by selectively querying the most informative data, reducing the need for extensive labeled datasets. This approach is particularly valuable for fields like cardiac research and scientific simulations, where data labeling becomes expensive and often impractical. Deep Active Learning (DAL) extends this concept to deep learning models, which are typically data hungry, where the focus is more to optimize data selection in discrete search spaces. Conversely, Explorative Active Learning (EAL), is tailored for exploration of continuous search spaces, employing machine learning techniques like Gaussian Processes. A recurring challenge in domain of DAL is difficulty to consistently reproduce the effectiveness of acquisition strategy in diverse experimental settings, a problem often linked to hyperparameters and experimental settings such as data augmentation. However, an often overlooked source of inconsistency is the choice of underlying model. Similarly, despite developments EAL, its applications to critical regions -- such as boundaries or areas of sharp functional change -- remains limited and often requires complex modifications to the existing acquisition strategies. In addition, reusability of trained model in new tasks is limited with strategies that assume that new task would fall under same distribution as the learned task or inclusion of complex techniques as reinforcement learning. Addressing these gaps, this dissertation outlines following key initiatives to try to solve them: (1) a comprehensive investigation of DAL on diverse dataset, network architectures and acquisition strategies to demonstrate the importance of architecture optimization and its impact on effectiveness in DAL. We further extend this to an application on DAL-based surrogate model development in scientific application. (2) The introduction of a novel acquisition strategy that emphasize data acquisition in regions of sharp functional value changes while maintaining minimal change to existing approaches. Additionally, we present a novel active learning framework that bridges DAL and EAL paradigm by combining a neural network-based surrogate model with EAL acquisition strategy, resulting in a reusable model applicable to unseen tasks.
Library of Congress Subject Headings
Deep learning (Machine learning); Computer architecture--Design and construction; Mathematical optimization
Publication Date
2025
Document Type
Dissertation
Student Type
Graduate
Degree Name
Computing and Information Sciences (Ph.D.)
Department, Program, or Center
Computing and Information Sciences Ph.D, Department of
College
Golisano College of Computing and Information Sciences
Advisor
Linwei Wang
Advisor/Committee Member
Richard D. Lange
Advisor/Committee Member
Rui Li
Recommended Citation
Bajracharya, Pradeep, "Active Learning Methodologies and Applications" (2025). Thesis. Rochester Institute of Technology. Accessed from
https://repository.rit.edu/theses/12330
Campus
RIT – Main Campus
Plan Codes
COMPIS-PHD
