Krupa Prag

Ms. Krupa Prag

University of the Witwatersrand, Johannesburg, Gauteng, South Africa

Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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21 March 2022 in IEEE Access
Verified
Journal Article
Open access
KPKrupa Prag
Krupa Prag
MWMatthew Woolway
Matthew Woolway
Turgay CelikTurgay Celik
Turgay Celik
This literature review extends and contributes to research on the development of data-driven optimal control. Previous reviews have documented the development of model-based and data-driven control in isolation and have not critically reviewed reinforcement learning approaches for adaptive data-driven optimal control frameworks. The presented review discusses the development of model-based to model-free adaptive controllers, highlighting the use of data in control frameworks. In data-driven control frameworks, reinforcement learning methods may be used to derive the optimal policy for dynamical systems. Attractive characteristics of these methods include not requiring a mathematical model of complex systems, their inherent adaptive control capabilities, being an unsupervised learning technique and their decision-making abilities, which are both an advantage and motivation behind this approach. This review considers previous reviews on these topics, including recent work on data-driven control methods. In addition, this review shows the use of data to derive system dynamics, determine the control policy using feedback information, and tune fixed controllers. Furthermore, the review summarises various data-driven methods and their corresponding characteristics. Finally, the review provides a taxonomy, a timeline and a concise narrative of the development of model-based to model-free data-driven adaptive control and underlines the limitations of these techniques due to the lack of theoretical analysis. Areas of further work include theoretical analysis on stability and robustness for data-driven control systems, explainability of black-box policy learning techniques and an evaluation of the impact of the extension of system simulators to include digital twins.

19 July 2021 in IEEE Access
Verified
Journal Article
Open access
KPKrupa Prag
Krupa Prag
MWMatthew Woolway
Matthew Woolway
Turgay CelikTurgay Celik
Turgay Celik
The data-driven model predictive control (DDMPC) scheme is proposed to obtain fast convergence to a desired reference and to be utilised to mitigate the destabilising effects that a DC-to-DC buck-boost converter (BBC) with an active load experiences. The DDMPC strategy uses the observed state to derive an optimal control policy using a reinforcement learning (RL) algorithm. The employed Proximal Policy Optimisation (PPO) algorithm’s performance is benchmarked against the PI controller. From the simulated results obtained using the MATLAB Simulink solver, the most robust methods for short settling time and stability were the hybrid methods. These methods take advantage of the short settling time provided by the PPO algorithm and the stability provided by the PI controller or the filtering mechanism over the transient time. The source code for this study is available on GitHub to support reproducible research in industrial electronics society.

23 June 2022 in Neural Computing and Applications
Verified
Journal Article
Closed access
PDF file
MKMaxine T. Khumalo
Maxine T. Khumalo
HCHazel A. Chieza
Hazel A. Chieza
KPKrupa Prag
Krupa Prag
MWMatthew Woolway
Matthew Woolway

5 August 2026 in BMC Medical Informatics and Decision Making
Verified
Journal Article
Open access
PDF file
RBRohail Hershil Bhana
Rohail Hershil Bhana
CVCharl Verwey
Charl Verwey
KPKrupa Prag
Krupa Prag
AMAvnish Magan
Avnish Magan
This study presents a clinically-derived, real-world paediatric pulmonology dataset across underrepresented areas in South Africa and benchmarks machine le

22 April 2022 in arXiv
Verified
Preprint
Open access
PDF file
MKMaxine T. Khumalo
Maxine T. Khumalo
HCHazel A. Chieza
Hazel A. Chieza
KPKrupa Prag
Krupa Prag
MWMatthew Woolway
Matthew Woolway
The intractability of deterministic solutions in solving $\mathcal{NP}$-Hard Combinatorial Optimisation Problems (COP) is well reported in the literature. One mechanism for overcoming this difficulty has been the use of efficient COP non-deterministic approaches. However, with the advent of quantum technology, these modern devices' potential to overcome this tractability limitation requires exploration. This paper juxtaposes classical and quantum optimisation algorithms' performance to solve two common COP, the Travelling Salesman Problem (TSP) and the Quadratic Assignment Problem (QAP). Two accepted classical optimisation methods, Branch and Bound (BNB) and Simulated Annealing (SA), are compared to two quantum optimisation methods, Variational Quantum Eigensolver (VQE) algorithm and Quantum Approximate Optimisation Algorithm (QAOA). These algorithms are respectively executed on both classical devices and IBM's suite of Noisy Intermediate-Scale Quantum (NISQ) devices. We have encoded the COP problems for the respective technologies and algorithms and provided the computational encodings for the NISQ devices. Our experimental results show that current classical devices significantly outperform the presently available NISQ devices, which agrees and extends with findings in the literature. Further, we introduce additional performance metrics to better compare the two approaches concerning computational time, feasibility and solution quality. Our results show that the VQE performs better than QAOA for these metrics, and we infer that this is due to the increased number of operations required. Additionally, we investigate the impact of a new set of basis gates on the quantum optimisation techniques and show they yield no notable improvement in the results. Finally, we present the shortcomings of state-of-the-art NISQ IBM quantum devices and argue for potential future work and investigation.