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Identification of partial differential equations from noisy data with integrated knowledge discovery and embedding using evolutionary neural networks
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作者 Hanyu Zhou Haochen Li yaomin zhao 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2024年第2期90-97,共8页
Identification of underlying partial differential equations(PDEs)for complex systems remains a formidable challenge.In the present study,a robust PDE identification method is proposed,demonstrating the ability to extr... Identification of underlying partial differential equations(PDEs)for complex systems remains a formidable challenge.In the present study,a robust PDE identification method is proposed,demonstrating the ability to extract accurate governing equations under noisy conditions without prior knowledge.Specifically,the proposed method combines gene expression programming,one type of evolutionary algorithm capable of generating unseen terms based solely on basic operators and functional terms,with symbolic regression neural networks.These networks are designed to represent explicit functional expressions and optimize them with data gradients.In particular,the specifically designed neural networks can be easily transformed to physical constraints for the training data,embedding the discovered PDEs to further optimize the metadata used for iterative PDE identification.The proposed method has been tested in four canonical PDE cases,validating its effectiveness without preliminary information and confirming its suitability for practical applications across various noise levels. 展开更多
关键词 PDE discovery Gene Expression Programming Deep Learning Knowledge embedding
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数据驱动框架下基于基因表达编程的非线性K-L湍流混合模型
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作者 谢寒松 赵耀民 张又升 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2023年第2期147-164,共18页
由Rayleigh-Taylor(RT)、Richtmyer-Meshkov(RM)、Kelvin-Helmholtz(KH)等流体力学界面不稳定性诱导的湍流混合现象广泛存在于自然界和工程问题中,准确预测其演化具有十分重要的意义.考虑到实际问题的高雷诺数及复杂性,在可预见的未来,... 由Rayleigh-Taylor(RT)、Richtmyer-Meshkov(RM)、Kelvin-Helmholtz(KH)等流体力学界面不稳定性诱导的湍流混合现象广泛存在于自然界和工程问题中,准确预测其演化具有十分重要的意义.考虑到实际问题的高雷诺数及复杂性,在可预见的未来,雷诺平均(RANS)方法仍将是工程实践中最具可实现性的选择.一般而言,传统RANS混合模型中至关重要的雷诺应力项是基于经典的Boussinesq线性涡粘假设封闭的.然而,这种线性模型无法充分描述在实际工程流动中发挥着重要作用的湍流各向异性特征.相比之下,非线性模型在这方面具有显著优势.本研究首次将基因表达编程(GEP)方法应用于湍流混合问题,发展了数据驱动的非线性K-L湍流混合模型.与常见的“黑箱”型机器学习模型不同,GEP模型显式给出模型方程,从而具有更强的物理可解释性.具体地,本研究基于二阶截断的广义Cayley-Hamilton非线性本构关系,利用GEP方法中的符号回归功能,形式化地给出了待封闭的模型系数与伽利略不变量之间的函数关系.此外,为了保证训练模型的物理性,我们将可实现性原则引入到了惩罚函数中.模型泛化性测试的结果表明:尽管新模型仅利用倾斜RT混合问题训练得到,但对于几个典型的混合问题均具有良好的鲁棒性.与标准的K-L模型相比,新模型不但具有更高的预测精度,而且能够更好地捕捉湍流的物理特性.此外,通过分析显式的封闭模型,本文进一步给出了新模型的预测效果得以提升的原因. 展开更多
关键词 Turbulent mixing GEP method Nonlinear model Machine learning Interpretable model
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