Numerical simulations are ubiquitous in science and engineering. Machine learning for science investigates how artificial neural architectures can learn from these simulations to speed up scientific discovery and engineering processes. Most of these architectures are trained in a supervised manner. They require tremendous amounts of data from simulations that are slow to generate and memory greedy. In this article, we present our ongoing work to design a training framework that alleviates those bottlenecks. It generates data in parallel with the training process. Such simultaneity induces a bias in the data available during the training. We present a strategy to mitigate this bias with a memory buffer. We test our framework on the multi-parametric Lorenz's attractor. We show the benefit of our framework compared to offline training and the success of our data bias mitigation strategy to capture the complex chaotic dynamics of the system.

这本数字本书包含在物理模拟的背景下与深度学习相关的一切实际和全面的一切。尽可能多，所有主题都带有Jupyter笔记本的形式的动手代码示例，以便快速入门。除了标准的受监督学习的数据中，我们将看看物理丢失约束，更紧密耦合的学习算法，具有可微分的模拟，以及加强学习和不确定性建模。我们生活在令人兴奋的时期：这些方法具有从根本上改变计算机模拟可以实现的巨大潜力。

深度强化学习（RL）导致了许多最近和开创性的进步。但是，这些进步通常以培训的基础体系结构的规模增加以及用于训练它们的RL算法的复杂性提高，而均以增加规模的成本。这些增长反过来又使研究人员更难迅速原型新想法或复制已发表的RL算法。为了解决这些问题，这项工作描述了ACME，这是一个用于构建新型RL算法的框架，这些框架是专门设计的，用于启用使用简单的模块化组件构建的代理，这些组件可以在各种执行范围内使用。尽管ACME的主要目标是为算法开发提供一个框架，但第二个目标是提供重要或最先进算法的简单参考实现。这些实现既是对我们的设计决策的验证，也是对RL研究中可重复性的重要贡献。在这项工作中，我们描述了ACME内部做出的主要设计决策，并提供了有关如何使用其组件来实施各种算法的进一步详细信息。我们的实验为许多常见和最先进的算法提供了基准，并显示了如何为更大且更复杂的环境扩展这些算法。这突出了ACME的主要优点之一，即它可用于实现大型，分布式的RL算法，这些算法可以以较大的尺度运行，同时仍保持该实现的固有可读性。这项工作提出了第二篇文章的版本，恰好与模块化的增加相吻合，对离线，模仿和从演示算法学习以及作为ACME的一部分实现的各种新代理。

科学机器学习的进步改善了现代计算科学和工程应用。数据驱动的方法（例如动态模式分解（DMD））可以从动态系统生成的时空数据中提取相干结构，并推断上述系统的不同方案。时空数据作为快照，每次瞬间包含空间信息。在现代工程应用中，高维快照的产生可能是时间和/或资源要求。在本研究中，我们考虑了在大型数值模拟中增强DMD工作流程的两种策略：（i）快照压缩以减轻磁盘压力； （ii）使用原位可视化图像在运行时重建动力学（或部分）。我们通过两个3D流体动力学模拟评估我们的方法，并考虑DMD重建解决方案。结果表明，快照压缩大大减少了所需的磁盘空间。我们已经观察到，损耗的压缩将存储降低了几乎$ 50 \％$，而信号重建和其他关注数量的相对错误则较低。我们还使用原位可视化工具将分析扩展到了直接生成的数据，在运行时生成状态向量的图像文件。在大型模拟中，快照的产生可能足够慢，可以使用批处理算法进行推理。流DMD利用增量SVD算法，并随着每个新快照的到来更新模式。我们使用流式DMD来重建原位生成的图像的动力学。我们证明此过程是有效的，并且重建的动力学是准确的。

This chapter sheds light on the synaptic organization of the brain from the perspective of computational neuroscience. It provides an introductory overview on how to account for empirical data in mathematical models, implement them in software, and perform simulations reflecting experiments. This path is demonstrated with respect to four key aspects of synaptic signaling: the connectivity of brain networks, synaptic transmission, synaptic plasticity, and the heterogeneity across synapses. Each step and aspect of the modeling and simulation workflow comes with its own challenges and pitfalls, which are highlighted and addressed in detail.

物理世界中的液体的难以解释需要准确地模拟其许多科学和工程应用的动态。传统上，建立得很好但资源密集的CFD溶解器提供了这种模拟。近年来已经看到了深入学习的替代模型，取代了这些求解器来缓解模拟过程。构建数据驱动代理的一些方法模拟了求解器迭代过程。他们推断出前一个液体的下一个状态。其他人直接从时间输入中推断出来。方法在其对空间信息的管理方面也有所不同。图形神经网络（GNN）可以解决CFD仿真中常用的不规则网格的特异性。在本文中，我们展示了我们正在进行的工作来设计一种用于不规则网格的新型直接时间GNN架构。它包括随着样条卷绕卷积连接的尺寸的连续。我们在von k {\'a} rm {\'a} n的vortex街基准测试中测试我们的架构。它实现了小的泛化误差，同时减轻了轨迹的误差累积。

Concept drift primarily refers to an online supervised learning scenario when the relation between the input data and the target variable changes over time. Assuming a general knowledge of supervised learning in this paper we characterize adaptive learning process, categorize existing strategies for handling concept drift, overview the most representative, distinct and popular techniques and algorithms, discuss evaluation methodology of adaptive algorithms, and present a set of illustrative applications. The survey covers the different facets of concept drift in an integrated way to reflect on the existing scattered state-of-the-art. Thus, it aims at providing a comprehensive introduction to the concept drift adaptation for researchers, industry analysts and practitioners.

机器学习的最新进展，加上低成本计算，廉价流传感器，数据存储和云技术的可用性导致了广泛的多学科研究活动，具有商业利益攸关方的重大兴趣和投资。基于物理方程式的机械模型，纯粹的数据驱动统计方法代表建模光谱的两端。新的混合动力车，以数据为中心的工程方法，利用世界各国和整合模拟和数据，都是一种强大的工具，具有对物理学科的变革影响。我们在集成模拟，机器学习和统计数据中审查了新兴领域的关键研究趋势和应用场景。我们突出了这种综合愿景可以解锁和概述阻止其实现的关键挑战的机会。我们还讨论了该领域的翻译方面的瓶颈以及现有劳动力和未来大学毕业生的长期上升要求。

The literature on machine learning in the context of data streams is vast and growing. However, many of the defining assumptions regarding data-stream learning tasks are too strong to hold in practice, or are even contradictory such that they cannot be met in the contexts of supervised learning. Algorithms are chosen and designed based on criteria which are often not clearly stated, for problem settings not clearly defined, tested in unrealistic settings, and/or in isolation from related approaches in the wider literature. This puts into question the potential for real-world impact of many approaches conceived in such contexts, and risks propagating a misguided research focus. We propose to tackle these issues by reformulating the fundamental definitions and settings of supervised data-stream learning with regard to contemporary considerations of concept drift and temporal dependence; and we take a fresh look at what constitutes a supervised data-stream learning task, and a reconsideration of algorithms that may be applied to tackle such tasks. Through and in reflection of this formulation and overview, helped by an informal survey of industrial players dealing with real-world data streams, we provide recommendations. Our main emphasis is that learning from data streams does not impose a single-pass or online-learning approach, or any particular learning regime; and any constraints on memory and time are not specific to streaming. Meanwhile, there exist established techniques for dealing with temporal dependence and concept drift, in other areas of the literature. For the data streams community, we thus encourage a shift in research focus, from dealing with often-artificial constraints and assumptions on the learning mode, to issues such as robustness, privacy, and interpretability which are increasingly relevant to learning in data streams in academic and industrial settings.

动态系统参见在物理，生物学，化学等自然科学中广泛使用，以及电路分析，计算流体动力学和控制等工程学科。对于简单的系统，可以通过应用基本物理法来导出管理动态的微分方程。然而，对于更复杂的系统，这种方法变得非常困难。数据驱动建模是一种替代范式，可以使用真实系统的观察来了解系统的动态的近似值。近年来，对数据驱动的建模技术的兴趣增加，特别是神经网络已被证明提供了解决广泛任务的有效框架。本文提供了使用神经网络构建动态系统模型的不同方式的调查。除了基础概述外，我们还审查了相关的文献，概述了这些建模范式必须克服的数值模拟中最重要的挑战。根据审查的文献和确定的挑战，我们提供了关于有前途的研究领域的讨论。

Machine learning-based modeling of physical systems has experienced increased interest in recent years. Despite some impressive progress, there is still a lack of benchmarks for Scientific ML that are easy to use but still challenging and representative of a wide range of problems. We introduce PDEBench, a benchmark suite of time-dependent simulation tasks based on Partial Differential Equations (PDEs). PDEBench comprises both code and data to benchmark the performance of novel machine learning models against both classical numerical simulations and machine learning baselines. Our proposed set of benchmark problems contribute the following unique features: (1) A much wider range of PDEs compared to existing benchmarks, ranging from relatively common examples to more realistic and difficult problems; (2) much larger ready-to-use datasets compared to prior work, comprising multiple simulation runs across a larger number of initial and boundary conditions and PDE parameters; (3) more extensible source codes with user-friendly APIs for data generation and baseline results with popular machine learning models (FNO, U-Net, PINN, Gradient-Based Inverse Method). PDEBench allows researchers to extend the benchmark freely for their own purposes using a standardized API and to compare the performance of new models to existing baseline methods. We also propose new evaluation metrics with the aim to provide a more holistic understanding of learning methods in the context of Scientific ML. With those metrics we identify tasks which are challenging for recent ML methods and propose these tasks as future challenges for the community. The code is available at https://github.com/pdebench/PDEBench.

机器人的形态和行为的互相适应变得与快速的3D-制造方法和高效的深强化学习算法的出现越来越重要。对于互相适应的方法应用到真实世界的一个主要挑战是由于模型和仿真不准确的模拟到现实的差距。然而，以前的工作主要集中在形态开发的分析模型，并用大量的用户群（微）模拟器的进化适应的研究，忽视的模拟到现实差距的存在和在现实世界中制造周期的成本。本文提出了一种新的办法，结合经典的高频率计算昂贵的图形神经网络的代理数据高效互相适应深层神经网络具有不同度的自由度数。在仿真结果表明，新方法可以通过有效的设计优化与离线强化学习相结合共同适应的生产周期这样一个有限的数量中的代理程序，它允许在今后的工作中直接应用到真实世界的互相适应任务评估

物理信息的神经网络（PINN）是神经网络（NNS），它们作为神经网络本身的组成部分编码模型方程，例如部分微分方程（PDE）。如今，PINN是用于求解PDE，分数方程，积分分化方程和随机PDE的。这种新颖的方法已成为一个多任务学习框架，在该框架中，NN必须在减少PDE残差的同时拟合观察到的数据。本文对PINNS的文献进行了全面的综述：虽然该研究的主要目标是表征这些网络及其相关的优势和缺点。该综述还试图将出版物纳入更广泛的基于搭配的物理知识的神经网络，这些神经网络构成了香草·皮恩（Vanilla Pinn）以及许多其他变体，例如物理受限的神经网络（PCNN），各种HP-VPINN，变量HP-VPINN，VPINN，VPINN，变体。和保守的Pinn（CPINN）。该研究表明，大多数研究都集中在通过不同的激活功能，梯度优化技术，神经网络结构和损耗功能结构来定制PINN。尽管使用PINN的应用范围广泛，但通过证明其在某些情况下比有限元方法（FEM）等经典数值技术更可行的能力，但仍有可能的进步，最著名的是尚未解决的理论问题。

Continual Learning (CL) is a field dedicated to devise algorithms able to achieve lifelong learning. Overcoming the knowledge disruption of previously acquired concepts, a drawback affecting deep learning models and that goes by the name of catastrophic forgetting, is a hard challenge. Currently, deep learning methods can attain impressive results when the data modeled does not undergo a considerable distributional shift in subsequent learning sessions, but whenever we expose such systems to this incremental setting, performance drop very quickly. Overcoming this limitation is fundamental as it would allow us to build truly intelligent systems showing stability and plasticity. Secondly, it would allow us to overcome the onerous limitation of retraining these architectures from scratch with the new updated data. In this thesis, we tackle the problem from multiple directions. In a first study, we show that in rehearsal-based techniques (systems that use memory buffer), the quantity of data stored in the rehearsal buffer is a more important factor over the quality of the data. Secondly, we propose one of the early works of incremental learning on ViTs architectures, comparing functional, weight and attention regularization approaches and propose effective novel a novel asymmetric loss. At the end we conclude with a study on pretraining and how it affects the performance in Continual Learning, raising some questions about the effective progression of the field. We then conclude with some future directions and closing remarks.

在整个计算科学中，越来越需要利用原始计算马力的持续改进，通过对蛮力的尺度锻炼的尺度增加，以增加网状元素数量的增加。例如，如果不考虑分子水平的相互作用，就不可能对纳米多孔介质的转运进行定量预测，即从紧密的页岩地层提取至关重要的碳氢化合物。同样，惯性限制融合模拟依赖于数值扩散来模拟分子效应，例如非本地转运和混合，而无需真正考虑分子相互作用。考虑到这两个不同的应用程序，我们开发了一种新颖的功能，该功能使用主动学习方法来优化局部细尺度模拟的使用来告知粗尺度流体动力学。我们的方法解决了三个挑战：预测连续性粗尺度轨迹，以推测执行新的精细分子动力学计算，动态地更新细度计算中的粗尺度，并量化神经网络模型中的不确定性。

基于合奏的大规模模拟动态系统对于广泛的科学和工程问题至关重要。模拟中使用的常规数值求解器受到时间整合的步长显着限制，这会阻碍效率和可行性，尤其是在需要高精度的情况下。为了克服这一限制，我们提出了一种数据驱动的校正方法，该方法允许使用大型步骤，同时补偿了积分误差以提高精度。该校正器以矢量值函数的形式表示，并通过神经网络建模以回归相空间中的误差。因此，我们将校正神经矢量（Neurvec）命名。我们表明，Neurvec可以达到与传统求解器具有更大步骤尺寸的传统求解器相同的准确性。我们从经验上证明，Neurvec可以显着加速各种数值求解器，并克服这些求解器的稳定性限制。我们关于基准问题的结果，从高维问题到混乱系统，表明Neurvec能够捕获主要的误差项并保持整体预测的统计数据。

在线持续学习是一个充满挑战的学习方案，模型必须从非平稳的数据流中学习，其中每个样本只能看到一次。主要的挑战是在避免灾难性遗忘的同时逐步学习，即在从新数据中学习时忘记先前获得的知识的问题。在这种情况下，一种流行的解决方案是使用较小的内存来保留旧数据并随着时间的推移进行排练。不幸的是，由于内存尺寸有限，随着时间的推移，内存的质量会恶化。在本文中，我们提出了OLCGM，这是一种基于新型重放的持续学习策略，该策略使用知识冷凝技术连续压缩记忆并更好地利用其有限的尺寸。样品冷凝步骤压缩了旧样品，而不是像其他重播策略那样将其删除。结果，实验表明，每当与数据的复杂性相比，每当记忆预算受到限制，OLCGM都会提高与最先进的重播策略相比的最终准确性。

Interacting with a complex world involves continual learning, in which tasks and data distributions change over time. A continual learning system should demonstrate both plasticity (acquisition of new knowledge) and stability (preservation of old knowledge). Catastrophic forgetting is the failure of stability, in which new experience overwrites previous experience. In the brain, replay of past experience is widely believed to reduce forgetting, yet it has been largely overlooked as a solution to forgetting in deep reinforcement learning. Here, we introduce CLEAR, a replay-based method that greatly reduces catastrophic forgetting in multi-task reinforcement learning. CLEAR leverages off-policy learning and behavioral cloning from replay to enhance stability, as well as on-policy learning to preserve plasticity. We show that CLEAR performs better than state-of-the-art deep learning techniques for mitigating forgetting, despite being significantly less complicated and not requiring any knowledge of the individual tasks being learned.

Lack of performance when it comes to continual learning over non-stationary distributions of data remains a major challenge in scaling neural network learning to more human realistic settings. In this work we propose a new conceptualization of the continual learning problem in terms of a temporally symmetric trade-off between transfer and interference that can be optimized by enforcing gradient alignment across examples. We then propose a new algorithm, Meta-Experience Replay (MER), that directly exploits this view by combining experience replay with optimization based meta-learning. This method learns parameters that make interference based on future gradients less likely and transfer based on future gradients more likely. 1 We conduct experiments across continual lifelong supervised learning benchmarks and non-stationary reinforcement learning environments demonstrating that our approach consistently outperforms recently proposed baselines for continual learning. Our experiments show that the gap between the performance of MER and baseline algorithms grows both as the environment gets more non-stationary and as the fraction of the total experiences stored gets smaller.

蒙特卡洛树搜索（MCT）是设计游戏机器人或解决顺序决策问题的强大方法。该方法依赖于平衡探索和开发的智能树搜索。MCT以模拟的形式进行随机抽样，并存储动作的统计数据，以在每个随后的迭代中做出更有教育的选择。然而，该方法已成为组合游戏的最新技术，但是，在更复杂的游戏（例如那些具有较高的分支因素或实时系列的游戏）以及各种实用领域（例如，运输，日程安排或安全性）有效的MCT应用程序通常需要其与问题有关的修改或与其他技术集成。这种特定领域的修改和混合方法是本调查的主要重点。最后一项主要的MCT调查已于2012年发布。自发布以来出现的贡献特别感兴趣。