In time series forecasting, decomposition-based algorithms break aggregate data into meaningful components and are therefore appreciated for their particular advantages in interpretability. Recent algorithms often combine machine learning (hereafter ML) methodology with decomposition to improve prediction accuracy. However, incorporating ML is generally considered to sacrifice interpretability inevitably. In addition, existing hybrid algorithms usually rely on theoretical models with statistical assumptions and focus only on the accuracy of aggregate predictions, and thus suffer from accuracy problems, especially in component estimates. In response to the above issues, this research explores the possibility of improving accuracy without losing interpretability in time series forecasting. We first quantitatively define interpretability for data-driven forecasts and systematically review the existing forecasting algorithms from the perspective of interpretability. Accordingly, we propose the W-R algorithm, a hybrid algorithm that combines decomposition and ML from a novel perspective. Specifically, the W-R algorithm replaces the standard additive combination function with a weighted variant and uses ML to modify the estimates of all components simultaneously. We mathematically analyze the theoretical basis of the algorithm and validate its performance through extensive numerical experiments. In general, the W-R algorithm outperforms all decomposition-based and ML benchmarks. Based on P50_QL, the algorithm relatively improves by 8.76% in accuracy on the practical sales forecasts of JD.com and 77.99% on a public dataset of electricity loads. This research offers an innovative perspective to combine the statistical and ML algorithms, and JD.com has implemented the W-R algorithm to make accurate sales predictions and guide its marketing activities.
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While federated learning has shown strong results in optimizing a machine learning model without direct access to the original data, its performance may be hindered by intermittent client availability which slows down the convergence and biases the final learned model. There are significant challenges to achieve both stable and bias-free training under arbitrary client availability. To address these challenges, we propose a framework named Federated Graph-based Sampling (FedGS), to stabilize the global model update and mitigate the long-term bias given arbitrary client availability simultaneously. First, we model the data correlations of clients with a Data-Distribution-Dependency Graph (3DG) that helps keep the sampled clients data apart from each other, which is theoretically shown to improve the approximation to the optimal model update. Second, constrained by the far-distance in data distribution of the sampled clients, we further minimize the variance of the numbers of times that the clients are sampled, to mitigate long-term bias. To validate the effectiveness of FedGS, we conduct experiments on three datasets under a comprehensive set of seven client availability modes. Our experimental results confirm FedGS's advantage in both enabling a fair client-sampling scheme and improving the model performance under arbitrary client availability. Our code is available at \url{https://github.com/WwZzz/FedGS}.
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In dense image segmentation tasks (e.g., semantic, panoptic), existing methods can hardly generalize well to unseen image domains, predefined classes, and image resolution & quality variations. Motivated by these observations, we construct a large-scale entity segmentation dataset to explore fine-grained entity segmentation, with a strong focus on open-world and high-quality dense segmentation. The dataset contains images spanning diverse image domains and resolutions, along with high-quality mask annotations for training and testing. Given the high-quality and -resolution nature of the dataset, we propose CropFormer for high-quality segmentation, which can improve mask prediction using high-res image crops that provide more fine-grained image details than the full image. CropFormer is the first query-based Transformer architecture that can effectively ensemble mask predictions from multiple image crops, by learning queries that can associate the same entities across the full image and its crop. With CropFormer, we achieve a significant AP gain of $1.9$ on the challenging fine-grained entity segmentation task. The dataset and code will be released at http://luqi.info/entityv2.github.io/.
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Three-dimensional (3D) freehand ultrasound (US) reconstruction without a tracker can be advantageous over its two-dimensional or tracked counterparts in many clinical applications. In this paper, we propose to estimate 3D spatial transformation between US frames from both past and future 2D images, using feed-forward and recurrent neural networks (RNNs). With the temporally available frames, a further multi-task learning algorithm is proposed to utilise a large number of auxiliary transformation-predicting tasks between them. Using more than 40,000 US frames acquired from 228 scans on 38 forearms of 19 volunteers in a volunteer study, the hold-out test performance is quantified by frame prediction accuracy, volume reconstruction overlap, accumulated tracking error and final drift, based on ground-truth from an optical tracker. The results show the importance of modelling the temporal-spatially correlated input frames as well as output transformations, with further improvement owing to additional past and/or future frames. The best performing model was associated with predicting transformation between moderately-spaced frames, with an interval of less than ten frames at 20 frames per second (fps). Little benefit was observed by adding frames more than one second away from the predicted transformation, with or without LSTM-based RNNs. Interestingly, with the proposed approach, explicit within-sequence loss that encourages consistency in composing transformations or minimises accumulated error may no longer be required. The implementation code and volunteer data will be made publicly available ensuring reproducibility and further research.
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Deep learning has attained remarkable success in many 3D visual recognition tasks, including shape classification, object detection, and semantic segmentation. However, many of these results rely on manually collecting densely annotated real-world 3D data, which is highly time-consuming and expensive to obtain, limiting the scalability of 3D recognition tasks. Thus, we study unsupervised 3D recognition and propose a Self-supervised-Self-Labeled 3D Recognition (SL3D) framework. SL3D simultaneously solves two coupled objectives, i.e., clustering and learning feature representation to generate pseudo-labeled data for unsupervised 3D recognition. SL3D is a generic framework and can be applied to solve different 3D recognition tasks, including classification, object detection, and semantic segmentation. Extensive experiments demonstrate its effectiveness. Code is available at https://github.com/fcendra/sl3d.
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Inspired by the success of contrastive learning (CL) in computer vision and natural language processing, graph contrastive learning (GCL) has been developed to learn discriminative node representations on graph datasets. However, the development of GCL on Heterogeneous Information Networks (HINs) is still in the infant stage. For example, it is unclear how to augment the HINs without substantially altering the underlying semantics, and how to design the contrastive objective to fully capture the rich semantics. Moreover, early investigations demonstrate that CL suffers from sampling bias, whereas conventional debiasing techniques are empirically shown to be inadequate for GCL. How to mitigate the sampling bias for heterogeneous GCL is another important problem. To address the aforementioned challenges, we propose a novel Heterogeneous Graph Contrastive Multi-view Learning (HGCML) model. In particular, we use metapaths as the augmentation to generate multiple subgraphs as multi-views, and propose a contrastive objective to maximize the mutual information between any pairs of metapath-induced views. To alleviate the sampling bias, we further propose a positive sampling strategy to explicitly select positives for each node via jointly considering semantic and structural information preserved on each metapath view. Extensive experiments demonstrate HGCML consistently outperforms state-of-the-art baselines on five real-world benchmark datasets.
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关于神经体系结构搜索(NAS)的现有研究主要集中于有效地搜索具有更好性能的网络体系结构。几乎没有取得进展,以系统地了解NAS搜索的架构是否对隐私攻击是强大的,而丰富的工作已经表明,人类设计的架构容易受到隐私攻击。在本文中,我们填补了这一空白,并系统地衡量了NAS体系结构的隐私风险。利用我们的测量研究中的见解,我们进一步探索了基于细胞的NAS架构的细胞模式,并评估细胞模式如何影响NAS搜索架构的隐私风险。通过广泛的实验,我们阐明了如何针对隐私攻击设计强大的NAS体系结构,还提供了一种通用方法,以了解NAS搜索的体系结构与其他隐私风险之间的隐藏相关性。
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创伤性脑损伤(TBI)患者的脑网络分析对于其意识水平评估和预后评估至关重要,这需要分割某些意识相关的大脑区域。但是,由于很难收集TBI患者的手动注释的MR扫描,因此很难构建TBI分割模型。数据增强技术可用于缓解数据稀缺问题。但是,常规数据增强策略(例如空间和强度转化)无法模仿创伤性大脑中的变形和病变,这限制了后续分割任务的性能。为了解决这些问题,我们提出了一种名为TBIGA的新型医学图像授课模型,以通过配对的脑标签图合成TBI MR扫描。我们的TBIGAN方法的主要优势在于,它可以同时生成TBI图像和相应的标签映射,这在以前的医学图像的先前涂上方法中尚未实现。我们首先按照粗到细节的方式在边缘信息的指导下生成成分的图像,然后将合成强度图像用作标签上填充的先验。此外,我们引入了基于注册的模板增强管道,以增加合成图像对的多样性并增强数据增强能力。实验结果表明,提出的TBIGAN方法可以产生具有高质量和有效标签图的足够合成的TBI图像,这可以大大改善与替代方案相比的2D和3D创伤性脑部分割性能。
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可进入的模型可以通过在表示理论和特征领域的语言中制定均衡性要求来提供非常通用和灵活的均衡性,这对许多视觉任务都是有效的。但是,由于3D旋转的数学更复杂,因此在2D情况下得出3D旋转模型要困难得多。在这项工作中,我们采用部分差分运算符(PDOS)来模型3D滤波器,并得出了通用的可检测3D CNN,称为PDO-S3DCNNS。我们证明,模棱两可的过滤器受线性约束的约束,可以在各种条件下有效地解决。据我们所知,PDO-S3DCNNS是3D旋转的最通用的CNN,因为它们涵盖了所有$ SO(3)$及其表示的所有常见子组,而现有方法只能应用于特定的组和特定组和表示。广泛的实验表明,我们的模型可以很好地保留在离散域中的均衡性,并且在SHREC'17检索和ISBI 2012分割任务上的表现都超过了以前的网络复杂性。
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节点注入对图神经网络(GNN)的攻击已作为一种实际的攻击场景而引起了人们的注意,攻击者会注入恶意节点,而不是修改节点功能或边缘以降低GNN的性能。尽管节点注射攻击最初取得了成功,但我们发现,通过防御方法,可以通过防御方法和限制其在实践中限制其攻击性能,从而很容易将注射的节点与原始正常节点区分开。为了解决上述问题,我们致力于伪装节点注入攻击,即伪装注入恶意节点(结构/属性)是对防御方法似乎合理/不察觉的普通淋巴结。图形数据的非欧亚人性质和缺乏人类的先验性质给伪装上伪装的形式化,实施和评估带来了巨大挑战。在本文中,我们首先提出并制定了从注射节点围绕的自我网络的忠诚度和多样性中注入的节点的伪装。然后,我们为节点注射攻击(即Cana)设计了一个对抗性伪装框架,以改善伪装,同时确保攻击性能。进一步设计了几种用于图形伪装的新型指标,以进行全面的评估。实验结果表明,当将现有的节点注入攻击方法与我们提出的CANA框架配置时,针对防御方法的攻击性能以及节点伪装将显着改善。
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