数字双胞胎是代表个人的计算机模型,例如组件,患者或过程。在许多情况下,我们希望从其数据中获取有关个人的知识,同时纳入不完美的物理知识,并从其他人那里学习。在本文中,我们介绍并演示了一种完全贝叶斯的方法,用于在每个人的物理参数中吸引人的物理参数的环境中学习数字双胞胎。对于每个人,该方法基于模型差异的贝叶斯校准。通过以高斯过程为模型的差异,不完美的低预后物理模型被解释了。利用贝叶斯分层模型的想法,通过在层次结构中的新级别连接数字双胞胎的联合概率模型。对于物理参数,可以将方法视为使用单个模型中的先验分布,该分布是关节模型中相应超参数的后部。为了学习个人之间的不完善物理,引入了两种方法,一种假设所有个人都具有相同的差异,并且可以看作是使用所有个人从所有个人那里学到的先前对代表差异的高斯过程参数的知识。基于与物理知识的先验,汉密尔顿蒙特卡洛方法相关的最新进展,并将其用于反问题,我们设置了一种推理方法,该方法允许我们的方法适用于基于部分微分方程和不在的单个数据的物理模型的计算可行性对齐。该方法在两个合成案例研究中得到了证明,这是文献中以前使用的玩具示例,该示例扩展到更多个体,并基于与高血压治疗相关的心血管微分方程模型。
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我们引入了一个计算有效的数据驱动框架,适合量化物理参数中的不确定性和计算机模型的模型公式,以微分方程为代表。我们构建了物理知识的先验,它们是多输出的GP先验,它们在协方差函数中编码模型的结构。我们将其扩展到一个完全贝叶斯的框架中,该框架量化了物理参数和模型预测的不确定性。由于物理模型通常是对实际过程的不完美描述,因此我们允许该模型通过考虑差异函数来偏离观察到的数据。为了获得后验分布,我们使用汉密尔顿蒙特卡洛采样。我们在使用血液动力学模型的仿真研究中证明了我们的方法,这些模型是时间依赖的微分方程。与我们的建模选择更复杂的模型模拟数据,目的是根据已知的数学连接学习物理参数。为了证明我们的方法的灵活性(使用热方程式的示例),还包括一个时空依赖的微分方程,其中还包括我们考虑偏见的数据收购过程的情况。最后,我们使用医学试验中获得的实际数据符合血液动力学模型。
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Machine learning model development and optimisation can be a rather cumbersome and resource-intensive process. Custom models are often more difficult to build and deploy, and they require infrastructure and expertise which are often costly to acquire and maintain. Machine learning product development lifecycle must take into account the need to navigate the difficulties of developing and deploying machine learning models. evoML is an AI-powered tool that provides automated functionalities in machine learning model development, optimisation, and model code optimisation. Core functionalities of evoML include data cleaning, exploratory analysis, feature analysis and generation, model optimisation, model evaluation, model code optimisation, and model deployment. Additionally, a key feature of evoML is that it embeds code and model optimisation into the model development process, and includes multi-objective optimisation capabilities.
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Vulnerability to adversarial attacks is a well-known weakness of Deep Neural Networks. While most of the studies focus on natural images with standardized benchmarks like ImageNet and CIFAR, little research has considered real world applications, in particular in the medical domain. Our research shows that, contrary to previous claims, robustness of chest x-ray classification is much harder to evaluate and leads to very different assessments based on the dataset, the architecture and robustness metric. We argue that previous studies did not take into account the peculiarity of medical diagnosis, like the co-occurrence of diseases, the disagreement of labellers (domain experts), the threat model of the attacks and the risk implications for each successful attack. In this paper, we discuss the methodological foundations, review the pitfalls and best practices, and suggest new methodological considerations for evaluating the robustness of chest xray classification models. Our evaluation on 3 datasets, 7 models, and 18 diseases is the largest evaluation of robustness of chest x-ray classification models.
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3D gaze estimation is most often tackled as learning a direct mapping between input images and the gaze vector or its spherical coordinates. Recently, it has been shown that pose estimation of the face, body and hands benefits from revising the learning target from few pose parameters to dense 3D coordinates. In this work, we leverage this observation and propose to tackle 3D gaze estimation as regression of 3D eye meshes. We overcome the absence of compatible ground truth by fitting a rigid 3D eyeball template on existing gaze datasets and propose to improve generalization by making use of widely available in-the-wild face images. To this end, we propose an automatic pipeline to retrieve robust gaze pseudo-labels from arbitrary face images and design a multi-view supervision framework to balance their effect during training. In our experiments, our method achieves improvement of 30% compared to state-of-the-art in cross-dataset gaze estimation, when no ground truth data are available for training, and 7% when they are. We make our project publicly available at https://github.com/Vagver/dense3Deyes.
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In recent years, graph neural networks (GNNs) have emerged as a promising tool for solving machine learning problems on graphs. Most GNNs are members of the family of message passing neural networks (MPNNs). There is a close connection between these models and the Weisfeiler-Leman (WL) test of isomorphism, an algorithm that can successfully test isomorphism for a broad class of graphs. Recently, much research has focused on measuring the expressive power of GNNs. For instance, it has been shown that standard MPNNs are at most as powerful as WL in terms of distinguishing non-isomorphic graphs. However, these studies have largely ignored the distances between the representations of nodes/graphs which are of paramount importance for learning tasks. In this paper, we define a distance function between nodes which is based on the hierarchy produced by the WL algorithm, and propose a model that learns representations which preserve those distances between nodes. Since the emerging hierarchy corresponds to a tree, to learn these representations, we capitalize on recent advances in the field of hyperbolic neural networks. We empirically evaluate the proposed model on standard node and graph classification datasets where it achieves competitive performance with state-of-the-art models.
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Climate change is expected to aggravate wildfire activity through the exacerbation of fire weather. Improving our capabilities to anticipate wildfires on a global scale is of uttermost importance for mitigating their negative effects. In this work, we create a global fire dataset and demonstrate a prototype for predicting the presence of global burned areas on a sub-seasonal scale with the use of segmentation deep learning models. Particularly, we present an open-access global analysis-ready datacube, which contains a variety of variables related to the seasonal and sub-seasonal fire drivers (climate, vegetation, oceanic indices, human-related variables), as well as the historical burned areas and wildfire emissions for 2001-2021. We train a deep learning model, which treats global wildfire forecasting as an image segmentation task and skillfully predicts the presence of burned areas 8, 16, 32 and 64 days ahead of time. Our work motivates the use of deep learning for global burned area forecasting and paves the way towards improved anticipation of global wildfire patterns.
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流媒体数据中对异常的实时检测正在受到越来越多的关注,因为它使我们能够提高警报,预测故障并检测到整个行业的入侵或威胁。然而,很少有人注意比较流媒体数据(即在线算法)的异常检测器的有效性和效率。在本文中,我们介绍了来自不同算法家族(即基于距离,密度,树木或投影)的主要在线检测器的定性合成概述,并突出了其构建,更新和测试检测模型的主要思想。然后,我们对在线检测算法的定量实验评估以及其离线对应物进行了彻底的分析。检测器的行为与不同数据集(即元功能)的特征相关,从而提供了对其性能的元级分析。我们的研究介绍了文献中几个缺失的见解,例如(a)检测器对随机分类器的可靠性以及什么数据集特性使它们随机执行; (b)在线探测器在何种程度上近似离线同行的性能; (c)哪种绘制检测器的策略和更新原始图最适合检测仅在数据集的功能子空间中可见的异常; (d)属于不同算法家族的探测器的有效性与效率之间的权衡是什么; (e)数据集的哪些特定特征产生在线算法以胜过所有其他特征。
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加强学习(RL)通常需要将问题分解为子任务,并在这些任务上构成学习的行为。 RL中的组成性有可能创建与其他系统功能接口的模块化子任务单元。但是,生成的组成模型需要表征成分特征鲁棒性的最小假设。我们使用分类观点为RL的\ emph {组成理论}开发了一个框架。鉴于组成性的分类表示,我们研究了足够的条件,在这些条件下,逐行学习与总体学习相同的最佳政策。特别是,我们的方法引入了类别$ \ mathsf {MDP} $,其对象是马尔可夫决策过程(MDPS),用作任务模型。我们表明$ \ Mathsf {MDP} $接收天然的构图操作,例如某些纤维产品和求职。这些操作在RL中具有明确的组成现象,并统一了现有的结构,例如在复合MDP中刺破危险状态并结合了状态行动对称性。我们还通过引入Zig-Zag图的语言来建模顺序任务完成,该图是在$ \ Mathsf {MDP} $中立即应用曲调操作的立即应用。
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最近,已经努力将信号阶段和时机(SPAT)消息标准化。这些消息包含所有信号交叉方法的信号相时机。因此,这些信息可用于有效的运动计划,从而导致更多均匀的交通流量和均匀的速度轮廓。尽管努力为半活化的信号控制系统提供了可靠的预测,但预测完全驱动控制的信号相时仍具有挑战性。本文提出了使用聚合的流量信号和循环检测器数据的时间序列预测框架。我们利用最先进的机器学习模型来预测未来信号阶段的持续时间。线性回归(LR),随机森林(RF)和长期内存(LSTM)神经网络的性能是针对天真基线模型进行评估的。结果基于瑞士苏黎世的全面信号控制系统的经验数据集表明,机器学习模型的表现优于常规预测方法。此外,基于树木的决策模型(例如RF)的表现最佳,其准确性满足实用应用要求。
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