arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2106.09780physics.flu-dyncs.LGnlin.CD
收藏

基于水库计算的混沌声学无约束优化

Gradient-free optimization of chaotic acoustics with reservoir computing

University of Cambridge(剑桥大学);Imperial College London(帝国理工学院);The Alan Turing Institute(艾伦·图灵研究所);TU Munich(慕尼黑工业大学)

Francisco Huhn, Luca Magri

摘要:

我们开发了一个通用的优化方法,找到的设计参数,最小化时间平均声学成本泛函。该方法是无梯度的,模型通知的,数据驱动的,基于回声状态网络的水库计算。首先,我们分析了回声状态网络在动态的短期和长期预测中的预测能力。我们发现,完全数据驱动和模型通知架构都可以学习混沌声学动力学,无论是时间准确性还是统计学。用具有一种声学模式的物理降阶模型来通知训练显著地提高了回声状态网络的准确性和鲁棒性,同时保持低计算成本。回声状态网络提供了对长时间动态的准确预测,否则通过集成控制方程来评估要优化的时间平均量将是昂贵的。其次,我们耦合回声状态网络与贝叶斯技术,探索设计热声参数空间。计算方法是最低限度的侵入。第三,我们找到了一组火焰参数,使混沌振荡的时间平均声能最小化,这是由正反馈与热源,如火焰在燃气轮机或火箭发动机。这些振荡被称为热声振荡。火焰参数的最佳设置被发现具有与蛮力网格搜索相同的精度,但是具有快一个数量级以上的收敛速度。这项工作开辟了新的可能性,非侵入式(“放手”)优化混沌系统,其中生成数据的成本,例如从高保真模拟和实验,是很高的。

英文摘要:

We develop a versatile optimization method, which finds the design parameters that minimize time-averaged acoustic cost functionals. The method is gradient-free, model-informed, and data-driven with reservoir computing based on echo state networks. First, we analyse the predictive capabilities of echo state networks both in the short- and long-time prediction of the dynamics. We find that both fully data-driven and model-informed architectures learn the chaotic acoustic dynamics, both time-accurately and statistically. Informing the training with a physical reduced-order model with one acoustic mode markedly improves the accuracy and robustness of the echo state networks, whilst keeping the computational cost low. Echo state networks offer accurate predictions of the long-time dynamics, which would be otherwise expensive by integrating the governing equations to evaluate the time-averaged quantity to optimize. Second, we couple echo state networks with a Bayesian technique to explore the design thermoacoustic parameter space. The computational method is minimally intrusive. Third, we find the set of flame parameters that minimize the time-averaged acoustic energy of chaotic oscillations, which are caused by the positive feedback with a heat source, such as a flame in gas turbines or rocket motors. These oscillations are known as thermoacoustic oscillations. The optimal set of flame parameters is found with the same accuracy as brute-force grid search, but with a convergence rate that is more than one order of magnitude faster. This work opens up new possibilities for non-intrusive ("hands-off") optimization of chaotic systems, in which the cost of generating data, for example from high-fidelity simulations and experiments, is high.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑