Urban traffic speed prediction aims to estimate the future traffic speed for improving the urban transportation services. Enormous efforts have been made on exploiting spatial correlations and temporal dependencies of traffic speed evolving patterns by leveraging explicit spatial relations (geographical proximity) through pre-defined geographical structures ({\it e.g.}, region grids or road networks). While achieving promising results, current traffic speed prediction methods still suffer from ignoring implicit spatial correlations (interactions), which cannot be captured by grid/graph convolutions. To tackle the challenge, we propose a generic model for enabling the current traffic speed prediction methods to preserve implicit spatial correlations. Specifically, we first develop a Dual-Transformer architecture, including a Spatial Transformer and a Temporal Transformer. The Spatial Transformer automatically learns the implicit spatial correlations across the road segments beyond the boundary of geographical structures, while the Temporal Transformer aims to capture the dynamic changing patterns of the implicit spatial correlations. Then, to further integrate both explicit and implicit spatial correlations, we propose a distillation-style learning framework, in which the existing traffic speed prediction methods are considered as the teacher model, and the proposed Dual-Transformer architectures are considered as the student model. The extensive experiments over three real-world datasets indicate significant improvements of our proposed framework over the existing methods.
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Determining causal effects of temporal multi-intervention assists decision-making. Restricted by time-varying bias, selection bias, and interactions of multiple interventions, the disentanglement and estimation of multiple treatment effects from individual temporal data is still rare. To tackle these challenges, we propose a comprehensive framework of temporal counterfactual forecasting from an individual multiple treatment perspective (TCFimt). TCFimt constructs adversarial tasks in a seq2seq framework to alleviate selection and time-varying bias and designs a contrastive learning-based block to decouple a mixed treatment effect into separated main treatment effects and causal interactions which further improves estimation accuracy. Through implementing experiments on two real-world datasets from distinct fields, the proposed method shows satisfactory performance in predicting future outcomes with specific treatments and in choosing optimal treatment type and timing than state-of-the-art methods.
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Transcranial temporal interference stimulation (tTIS) has been reported to be effective in stimulating deep brain structures in experimental studies. However, a computational framework for optimizing the tTIS strategy and simulating the impact of tTIS on the brain is still lacking, as previous methods rely on predefined parameters and hardly adapt to additional constraints. Here, we propose a general framework, namely multi-objective optimization via evolutionary algorithm (MOVEA), to solve the nonconvex optimization problem for various stimulation techniques, including tTIS and transcranial alternating current stimulation (tACS). By optimizing the electrode montage in a two-stage structure, MOVEA can be compatible with additional constraints (e.g., the number of electrodes, additional avoidance regions), and MOVEA can accelerate to obtain the Pareto fronts. These Pareto fronts consist of a set of optimal solutions under different requirements, suggesting a trade-off relationship between conflicting objectives, such as intensity and focality. Based on MOVEA, we make comprehensive comparisons between tACS and tTIS in terms of intensity, focality and maneuverability for targets of different depths. Our results show that although the tTIS can only obtain a relatively low maximum achievable electric field strength, for example, the maximum intensity of motor area under tTIS is 0.42V /m, while 0.51V /m under tACS, it helps improve the focality by reducing 60% activated volume outside the target. We further perform ANOVA on the stimulation results of eight subjects with tACS and tTIS. Despite the individual differences in head models, our results suggest that tACS has a greater intensity and tTIS has a higher focality. These findings provide guidance on the choice between tACS and tTIS and indicate a great potential in tTIS-based personalized neuromodulation. Code will be released soon.
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图对比度学习(GCL)一直是图形自学学习的新兴解决方案。 GCL的核心原理是在正视图中降低样品之间的距离,但在负视图中增加样品之间的距离。在实现有希望的性能的同时,当前的GCL方法仍然受到两个局限性:(1)增强的不可控制的有效性,该图扰动可能会产生针对语义和图形数据的特征流程的无效视图; (2)不可靠的二进制对比理由,对于非欧几里得图数据而言,难以确定构造观点的积极性和负面性。为了应对上述局限性,我们提出了一个新的对比度学习范式,即图形软对比度学习(GSCL),该范例通过排名的社区无需任何增强和二进制对比符合性,在较细性的范围内进行对比度学习。 GSCL建立在图接近的基本假设上,即连接的邻居比遥远的节点更相似。具体而言,我们在配对和列表的封闭式排名中,以保留附近的相对排名关系。此外,随着邻里规模的指数增长,考虑了更多的啤酒花,我们提出了提高学习效率的邻里抽样策略。广泛的实验结果表明,我们提出的GSCL可以始终如一地在各种公共数据集上实现与GCL相当复杂的各种公共数据集的最新性能。
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无监督的视频域适应是一项实用但具有挑战性的任务。在这项工作中,我们第一次从脱离视图中解决了它。我们的关键想法是在适应过程中将与域相关的信息从数据中删除。具体而言,我们考虑从两组潜在因素中生成跨域视频,一个编码静态域相关信息,另一个编码时间和语义相关的信息。然后开发转移顺序的VAE(Transvae)框架以建模这种产生。为了更好地适应适应,我们进一步提出了几个目标,以限制Transvae中的潜在因素。与几种最先进的方法相比,对UCF-HMDB,小丑和Epic-Kitchens数据集进行了广泛的实验验证了Transvae的有效性和优势。代码可在https://github.com/ldkong1205/transvae上公开获取。
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学习(IL)是数据挖掘应用中广泛存在的重要问题。典型的IL方法利用直观的类努力重新采样或重新重量直接平衡训练集。然而,特定领域的一些最近的研究努力表明,在没有课堂上操纵的情况下可以实现类别不平衡的学习。这提示我们思考两种不同的IL战略之间的关系和班级不平衡的性质。从根本上说,它们对应于IL中存在的两个必要的不平衡:来自不同类别的示例之间的数量差异以及单个类中的易于和硬示例之间,即阶级和级别的帧内不平衡。现有工程未能明确地考虑不平衡,因此遭受次优绩效。鉴于此,我们呈现了双重平衡的集合,即杜博士,一个多功能的集合学习框架。与普遍方法不同,Dube直接执行级别的级别和级别的平衡,而无需依赖基于距离的距离的计算,这允许它在计算效率时实现竞争性能。我们还提出了关于基于杜博伊的不同间/内部平衡策略的优缺点的详细讨论和分析。广泛的实验验证了所提出的方法的有效性。代码和示例可在https://github.com/iCde20222sub/duplebalance获得。
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Imbalanced-leasemble,缩写为IMBens,是一个开源Python工具箱,用于快速实现和部署类别 - 不平衡数据的集合学习算法。它提供对多个最先进的集合不平衡学习(EIL)方法,可视化器和公用事业功能的访问,以处理类别不平衡问题。这些集合方法包括基于重采样的,例如/过度采样,以及重量基于/过度采样,例如,敏感的学习。除了实现之外,我们还扩展了传统的二进制EIL算法,与多级支持和重采样调度程序等新功能,从而使它们能够处理更复杂的任务。该软件包是在简单的,良好的API设计中开发的,遵循Scikit-Gearn的易于使用。 IMBens在MIT开源许可证下发布,可以从Python包索引(PYPI)安装。 https://github.com/zhiningliu1998/imbalanced-ensemble可以使用源代码,二进制文件,详细文档和使用示例。
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本文研究了如何改善接受深入增强学习训练的导航剂的概括性能和学习速度(DRL)。尽管DRL在无机MAP导航中表现出巨大的潜力,但在训练场景中表现良好的DRL代理在不熟悉的情况下经常表现不佳。在这项工作中,我们建议LIDAR读数的表示是代理商效果退化的关键因素,并提出了一种强大的输入预处理(IP)方法来解决此问题。由于这种方法使用适应性的参数倒数函数来预处理激光雷达读数,因此我们将此方法称为IPAPREC及其归一化版本为IPAPRECN。 IPAPREC/IPAPRECN可以突出显示重要的短距离值,并压缩激光扫描中较重要的长距离值的范围,该值很好地解决了由激光扫描的常规表示引起的问题。通过广泛的模拟和现实世界实验来验证它们的高性能。结果表明,与常规方法相比,我们的方法可以大大改善导航剂的概括性能,并大大减少训练时间。
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Masked image modeling (MIM) performs strongly in pre-training large vision Transformers (ViTs). However, small models that are critical for real-world applications cannot or only marginally benefit from this pre-training approach. In this paper, we explore distillation techniques to transfer the success of large MIM-based pre-trained models to smaller ones. We systematically study different options in the distillation framework, including distilling targets, losses, input, network regularization, sequential distillation, etc, revealing that: 1) Distilling token relations is more effective than CLS token- and feature-based distillation; 2) An intermediate layer of the teacher network as target perform better than that using the last layer when the depth of the student mismatches that of the teacher; 3) Weak regularization is preferred; etc. With these findings, we achieve significant fine-tuning accuracy improvements over the scratch MIM pre-training on ImageNet-1K classification, using all the ViT-Tiny, ViT-Small, and ViT-base models, with +4.2%/+2.4%/+1.4% gains, respectively. Our TinyMIM model of base size achieves 52.2 mIoU in AE20K semantic segmentation, which is +4.1 higher than the MAE baseline. Our TinyMIM model of tiny size achieves 79.6% top-1 accuracy on ImageNet-1K image classification, which sets a new record for small vision models of the same size and computation budget. This strong performance suggests an alternative way for developing small vision Transformer models, that is, by exploring better training methods rather than introducing inductive biases into architectures as in most previous works. Code is available at https://github.com/OliverRensu/TinyMIM.
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Given the increasingly intricate forms of partial differential equations (PDEs) in physics and related fields, computationally solving PDEs without analytic solutions inevitably suffers from the trade-off between accuracy and efficiency. Recent advances in neural operators, a kind of mesh-independent neural-network-based PDE solvers, have suggested the dawn of overcoming this challenge. In this emerging direction, Koopman neural operator (KNO) is a representative demonstration and outperforms other state-of-the-art alternatives in terms of accuracy and efficiency. Here we present KoopmanLab, a self-contained and user-friendly PyTorch module of the Koopman neural operator family for solving partial differential equations. Beyond the original version of KNO, we develop multiple new variants of KNO based on different neural network architectures to improve the general applicability of our module. These variants are validated by mesh-independent and long-term prediction experiments implemented on representative PDEs (e.g., the Navier-Stokes equation and the Bateman-Burgers equation) and ERA5 (i.e., one of the largest high-resolution data sets of global-scale climate fields). These demonstrations suggest the potential of KoopmanLab to be considered in diverse applications of partial differential equations.
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