用不确定性引导在线集成,提升聚变数据流中模型的适应能力。
Uncertainty Guided Online Ensemble for Non-stationary Data Streams in Fusion Science
- 基于历史数据不同时间窗口的集成学习,结合不确定性评估动态调整权重。
- 相比静态模型误差降低80%,比传统在线学习再降6%~10%。
- 适合需要持续高精度预测的聚变实验场景,尤其适用于无实时标签的情况。
机器学习在下一代聚变装置的研发与运行中具有关键作用。聚变数据呈现非平稳特性,因实验演化与设备老化导致分布漂移。传统机器学习假设数据分布稳定,面对此类数据流时性能下降。尽管在线学习已在其他领域应用,但在聚变研究中仍较少探索。本文将在线学习应用于DIII-D托卡马克装置中环向场(TF)线圈偏移的预测任务。结果表明,在线学习对维持模型性能至关重要,相比静态模型可使误差降低80%。然而,传统在线学习因缺乏预测前的真实标签,常出现短期性能下降。为此,我们提出一种不确定性引导的在线集成方法:利用深度高斯过程近似(DGPA)进行校准的不确定性估计,并以该不确定性指导元算法,融合多个在不同历史窗口训练的学习器进行预测。同时,DGPA提供预测伴随的不确定性,供决策者参考。所提方法相较标准单模型在线学习,进一步降低预测误差约6%和10%。
原文摘要 · Abstract (English)
Machine Learning (ML) is poised to play a pivotal role in the development and operation of next-generation fusion devices. Fusion data shows non-stationary behavior with distribution drifts, resulted by both experimental evolution and machine wear-and-tear. ML models assume stationary distribution and fail to maintain performance when encountered with such non-stationary data streams. Online learning techniques have been leveraged in other domains, however it has been largely unexplored for fusion applications. In this paper, we present an application of online learning to continuously adapt to drifting data stream for prediction of Toroidal Field (TF) coils deflection at the DIII-D fusion facility. The results demonstrate that online learning is critical to maintain ML model performance and reduces error by 80% compared to a static model. Moreover, traditional online learning can suffer from short-term performance degradation as ground truth is not available before making the predictions. As such, we propose an uncertainty guided online ensemble method to further improve the performance. The Deep Gaussian Process Approximation (DGPA) technique is leveraged for calibrated uncertainty estimation and the uncertainty values are then used to guide a meta-algorithm that produces predictions based on an ensemble of learners trained on different horizon of historical data. The DGPA also provides uncertainty estimation along with the predictions for decision makers. The online ensemble and the proposed uncertainty guided online ensemble reduces predictions error by about 6%, and 10% respectively over standard single model based online learning.
Thank you to arXiv for use of its open access interoperability. PaperDance 不是 arXiv 官方产品;中文卡片由大模型生成,请以原文为准。