用物理约束神经网络模拟斯匹次卑尔根岛污染扩散,揭示逆温层如何加剧雾霾。
Collocation-based Robust Physics Informed Neural Networks for time-dependent simulations of pollution propagation under thermal inversion conditions on Spitsbergen
- 基于变分框架构建鲁棒损失函数,直接关联真实逼近误差。
- 在逆温条件下模拟显示颗粒物浓度显著升高,恶化空气质量。
- 采用采样点策略加速训练,适用于非线性问题的高效求解。
本文提出一种用于动态污染传播模拟的物理信息神经网络框架,针对移动排放源引起的时变污染扩散问题。建立了时变对流-扩散问题的鲁棒变分框架,并证明了离散弱形式的有界性和inf-sup稳定性。基于此数学基础,构造了一个与真实逼近误差(神经网络近似与未知精确解之差)直接相关的鲁棒损失函数。同时引入基于采样点的策略以加速神经网络训练,并将模型扩展至非线性Burgers型方程。以斯匹次卑尔根岛朗伊尔城雪地摩托交通导致的污染为案例研究,结合现场传感器实测数据,分析逆温层对污染物累积的影响。结果表明,逆温层会困住近地面密集潮湿空气,显著提升颗粒物(PM)浓度,严重恶化局部空气质量。与使用等几何分析的线性显式动力学求解器相比,本方法求解非线性非定常问题仅慢四倍,使其在保持类似线性计算成本下研究非线性扩展具有重要意义。
原文摘要 · Abstract (English)
In this paper, we propose a Physics-Informed Neural Network framework for time-dependent simulations of pollution propagation originating from moving emission sources. We formulate a robust variational framework for the time-dependent advection-diffusion problem and establish the boundedness and inf-sup stability of the corresponding discrete weak formulation. Based on this mathematical foundation, we construct a robust loss function that is directly related to the true approximation error, defined as the difference between the neural network approximation and the (unknown) exact solution. Additionally, a collocation-based strategy is introduced to speed up neural network training. We also extend our model to the non-linear Burgers-type equations. As a case study, we investigate pollution propagation caused by snowmobile traffic in Longyearbyen, Spitsbergen, supported by detailed in-field measurements collected using dedicated sensors. The proposed framework is applied to analyze the effects of thermal inversion on pollutant accumulation. Our results demonstrate that thermal inversion traps dense and humid air masses near the ground, significantly enhancing particulate matter (PM) concentration and worsening local air quality. We compare our method to linear computational cost explicit dynamics solver using isogeometric analysis. We show that our method can solve non-linear non-stationary problem four times slower than IGA solver can solve the linear problem. It makes it particularly interesting to investigate the non-linear extensions with similar computational cost as the linear formulation.
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