连续时间过程随机控制中的一个根本假设是底层(扩散)过程的动态是已知的。然而,这通常在实践中显然没有实现。另一方面,在过去几十年中,已经开发出用于连续时间过程的漂移(和波动性)的非参数估计的丰富理论。本文的目的是将随机控制的技术与来自随机过程的统计方法一起带来的技术,以便在同一时间找到以合理的方式学习底层过程的动态。更确切地说,我们研究了长期平均脉冲控制问题,是古典福斯曼木材采伐问题的随机版本。立即出现的问题之一是探索 - 剥削困境,因为机器学习中的问题众所周知。我们建议通过以合适的方式结合勘探和剥削期间来处理这个问题。我们的主要发现是,这种结构可以基于估算器的收敛率,以实现不变的密度。使用此项,我们获得平均累积遗憾是统一的订单$ O({T ^ { - 1/3})$。
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Automatic Image Cropping is a challenging task with many practical downstream applications. The task is often divided into sub-problems - generating cropping candidates, finding the visually important regions, and determining aesthetics to select the most appealing candidate. Prior approaches model one or more of these sub-problems separately, and often combine them sequentially. We propose a novel convolutional neural network (CNN) based method to crop images directly, without explicitly modeling image aesthetics, evaluating multiple crop candidates, or detecting visually salient regions. Our model is trained on a large dataset of images cropped by experienced editors and can simultaneously predict bounding boxes for multiple fixed aspect ratios. We consider the aspect ratio of the cropped image to be a critical factor that influences aesthetics. Prior approaches for automatic image cropping, did not enforce the aspect ratio of the outputs, likely due to a lack of datasets for this task. We, therefore, benchmark our method on public datasets for two related tasks - first, aesthetic image cropping without regard to aspect ratio, and second, thumbnail generation that requires fixed aspect ratio outputs, but where aesthetics are not crucial. We show that our strategy is competitive with or performs better than existing methods in both these tasks. Furthermore, our one-stage model is easier to train and significantly faster than existing two-stage or end-to-end methods for inference. We present a qualitative evaluation study, and find that our model is able to generalize to diverse images from unseen datasets and often retains compositional properties of the original images after cropping. Our results demonstrate that explicitly modeling image aesthetics or visual attention regions is not necessarily required to build a competitive image cropping algorithm.
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Information extraction from scholarly articles is a challenging task due to the sizable document length and implicit information hidden in text, figures, and citations. Scholarly information extraction has various applications in exploration, archival, and curation services for digital libraries and knowledge management systems. We present MORTY, an information extraction technique that creates structured summaries of text from scholarly articles. Our approach condenses the article's full-text to property-value pairs as a segmented text snippet called structured summary. We also present a sizable scholarly dataset combining structured summaries retrieved from a scholarly knowledge graph and corresponding publicly available scientific articles, which we openly publish as a resource for the research community. Our results show that structured summarization is a suitable approach for targeted information extraction that complements other commonly used methods such as question answering and named entity recognition.
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Many scientific domains gather sufficient labels to train machine algorithms through human-in-the-loop techniques provided by the Zooniverse.org citizen science platform. As the range of projects, task types and data rates increase, acceleration of model training is of paramount concern to focus volunteer effort where most needed. The application of Transfer Learning (TL) between Zooniverse projects holds promise as a solution. However, understanding the effectiveness of TL approaches that pretrain on large-scale generic image sets vs. images with similar characteristics possibly from similar tasks is an open challenge. We apply a generative segmentation model on two Zooniverse project-based data sets: (1) to identify fat droplets in liver cells (FatChecker; FC) and (2) the identification of kelp beds in satellite images (Floating Forests; FF) through transfer learning from the first project. We compare and contrast its performance with a TL model based on the COCO image set, and subsequently with baseline counterparts. We find that both the FC and COCO TL models perform better than the baseline cases when using >75% of the original training sample size. The COCO-based TL model generally performs better than the FC-based one, likely due to its generalized features. Our investigations provide important insights into usage of TL approaches on multi-domain data hosted across different Zooniverse projects, enabling future projects to accelerate task completion.
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Natural laws are often described through differential equations yet finding a differential equation that describes the governing law underlying observed data is a challenging and still mostly manual task. In this paper we make a step towards the automation of this process: we propose a transformer-based sequence-to-sequence model that recovers scalar autonomous ordinary differential equations (ODEs) in symbolic form from time-series data of a single observed solution of the ODE. Our method is efficiently scalable: after one-time pretraining on a large set of ODEs, we can infer the governing laws of a new observed solution in a few forward passes of the model. Then we show that our model performs better or on par with existing methods in various test cases in terms of accurate symbolic recovery of the ODE, especially for more complex expressions.
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Recent 3D-based manipulation methods either directly predict the grasp pose using 3D neural networks, or solve the grasp pose using similar objects retrieved from shape databases. However, the former faces generalizability challenges when testing with new robot arms or unseen objects; and the latter assumes that similar objects exist in the databases. We hypothesize that recent 3D modeling methods provides a path towards building digital replica of the evaluation scene that affords physical simulation and supports robust manipulation algorithm learning. We propose to reconstruct high-quality meshes from real-world point clouds using state-of-the-art neural surface reconstruction method (the Real2Sim step). Because most simulators take meshes for fast simulation, the reconstructed meshes enable grasp pose labels generation without human efforts. The generated labels can train grasp network that performs robustly in the real evaluation scene (the Sim2Real step). In synthetic and real experiments, we show that the Real2Sim2Real pipeline performs better than baseline grasp networks trained with a large dataset and a grasp sampling method with retrieval-based reconstruction. The benefit of the Real2Sim2Real pipeline comes from 1) decoupling scene modeling and grasp sampling into sub-problems, and 2) both sub-problems can be solved with sufficiently high quality using recent 3D learning algorithms and mesh-based physical simulation techniques.
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医学图像分割模型的性能指标用于衡量参考注释和预测之间的一致性。在开发此类模型中,使用了一组通用指标,以使结果更具可比性。但是,公共数据集中的分布与临床实践中遇到的案例之间存在不匹配。许多常见的指标无法衡量这种不匹配的影响,尤其是对于包含不确定,小或空参考注释的临床数据集。因此,可能无法通过此类指标来验证模型在临床上有意义的一致性。评估临床价值的维度包括独立于参考注释量的大小,考虑参考注释的不确定性,体积计和/或位置一致性的奖励以及对空参考注释正确分类的奖励。与普通的公共数据集不同,我们的内部数据集更具代表性。它包含不确定的,小或空的参考注释。我们研究了有关深度学习框架的预测的公开度量指标,以确定哪些设置共同指标可提供有意义的结果。我们将公共基准数据集进行比较而没有不确定,小或空参考注释。该代码将发布。
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随着机器人越来越多地进入以人为本的环境,他们不仅必须能够在人类周围安全地浏览,还必须遵守复杂的社会规范。人类通常在围绕他人围绕他人(尤其是在密集占据的空间中)时,通常通过手势和面部表情依靠非语言交流。因此,机器人还需要能够将手势解释为解决社会导航任务的一部分。为此,我们提出了一种新型的社会导航方法,将基于图像的模仿学习与模型预测性控制结合在一起。手势是基于在图像流中运行的神经网络来解释的,而我们使用最先进的模型预测控制算法来求解点对点导航任务。我们将方法部署在真实的机器人上,并展示我们的方法对四个手势游动场景的有效性:左/右,跟随我,然后圈出一个圆圈。我们的实验表明,我们的方法能够成功地解释复杂的人类手势,并将其用作信号,以生成具有社会符合性的导航任务的轨迹。我们基于与机器人相互作用的参与者的原位等级验证了我们的方法。
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噪声的去除或取消对成像和声学具有广泛的应用。在日常生活中,Denoising甚至可能包括对地面真理不忠的生成方面。但是,对于科学应用,denoing必须准确地重现地面真相。在这里,我们展示了如何通过深层卷积神经网络来定位数据,从而以定量精度出现弱信号。特别是,我们研究了晶体材料的X射线衍射。我们证明,弱信号是由电荷排序引起的,在嘈杂的数据中微不足道的信号,在DeNo的数据中变得可见和准确。通过对深度神经网络的监督培训,具有成对的低噪声数据,可以通过监督培训来实现这一成功。这样,神经网络就可以了解噪声的统计特性。我们证明,使用人造噪声(例如泊松和高斯)不会产生这种定量准确的结果。因此,我们的方法说明了一种实用的噪声过滤策略,可以应用于具有挑战性的获取问题。
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隐私已成为机器学习的主要问题。实际上,联合学习是出于隐私问题而激发的,因为它不允许传输私人数据,而仅传输中间更新。但是,联邦学习并不总是保证隐私保护,因为中间更新也可能揭示敏感信息。在本文中,我们对高斯混合模型的联合期望最大化算法进行了明确的信息理论分析,并证明了中间更新可能导致严重的隐私泄漏。为了解决隐私问题,我们提出了一个完全分散的隐私解决方案,该解决方案能够安全地计算每个最大化步骤中的更新。此外,我们考虑了两种不同类型的安全攻击:诚实但有趣而窃听的对手模型。数值验证表明,就准确性和隐私水平而言,与现有方法相比,所提出的方法具有优越的性能。
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