论文标题

校准,模拟,样品

Calibrate, Emulate, Sample

论文作者

Cleary, Emmet, Garbuno-Inigo, Alfredo, Lan, Shiwei, Schneider, Tapio, Stuart, Andrew M

论文摘要

在应用中产生的许多参数估计问题是贝叶斯倒置框架中最好的。这不仅允许对参数进行估计,还允许量化估计值中的不确定性。通常,在此类问题中,参数到数据图的评估非常昂贵,并且地图的计算衍生物或衍生品接合可能是不可行的。此外,在许多应用中,只有对地图的嘈杂评估才能可用。我们在这种设置中提出了一种贝叶斯反演的方法,该方法基于集合卡尔曼反转方法的无衍生优化功能。总体方法是首先使用集合卡尔曼采样(EKS)来校准未知参数以适合数据。其次,使用EK的输出模拟参数到数据映射;第三,要从近似贝叶斯后分布进行样品,其中参数到数据图被其模拟器取代。这导致了一种近似贝叶斯推论的原则方法,该方法仅需要对参数到数据映射的(可能是嘈杂的近似近似值)进行少量评估。它不需要此地图的衍生物,而是利用了集合卡尔曼方法的记录的能力。此外,EK具有理想的特性,即它将参数集合进展到大部分参数后质量所在区域,从而在方法论的仿真阶段很好地定位了它们。从本质上讲,EKS方法为设计问题提供了一种廉价的解决方案,即在何处将点数放置在参数空间中,以有效地训练参数与数据图的模拟器,以实现贝叶斯反转的目的。

Many parameter estimation problems arising in applications are best cast in the framework of Bayesian inversion. This allows not only for an estimate of the parameters, but also for the quantification of uncertainties in the estimates. Often in such problems the parameter-to-data map is very expensive to evaluate, and computing derivatives of the map, or derivative-adjoints, may not be feasible. Additionally, in many applications only noisy evaluations of the map may be available. We propose an approach to Bayesian inversion in such settings that builds on the derivative-free optimization capabilities of ensemble Kalman inversion methods. The overarching approach is to first use ensemble Kalman sampling (EKS) to calibrate the unknown parameters to fit the data; second, to use the output of the EKS to emulate the parameter-to-data map; third, to sample from an approximate Bayesian posterior distribution in which the parameter-to-data map is replaced by its emulator. This results in a principled approach to approximate Bayesian inference that requires only a small number of evaluations of the (possibly noisy approximation of the) parameter-to-data map. It does not require derivatives of this map, but instead leverages the documented power of ensemble Kalman methods. Furthermore, the EKS has the desirable property that it evolves the parameter ensembles towards the regions in which the bulk of the parameter posterior mass is located, thereby locating them well for the emulation phase of the methodology. In essence, the EKS methodology provides a cheap solution to the design problem of where to place points in parameter space to efficiently train an emulator of the parameter-to-data map for the purposes of Bayesian inversion.

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