Unsupervised Domain Adaptation (UDA) has emerged as a powerful solution for the domain shift problem via transferring the knowledge from a labeled source domain to a shifted unlabeled target domain. Despite the prevalence of UDA for visual applications, it remains relatively less explored for time-series applications. In this work, we propose a novel lightweight contrastive domain adaptation framework called CoTMix for time-series data. Unlike existing approaches that either use statistical distances or adversarial techniques, we leverage contrastive learning solely to mitigate the distribution shift across the different domains. Specifically, we propose a novel temporal mixup strategy to generate two intermediate augmented views for the source and target domains. Subsequently, we leverage contrastive learning to maximize the similarity between each domain and its corresponding augmented view. The generated views consider the temporal dynamics of time-series data during the adaptation process while inheriting the semantics among the two domains. Hence, we gradually push both domains towards a common intermediate space, mitigating the distribution shift across them. Extensive experiments conducted on four real-world time-series datasets show that our approach can significantly outperform all state-of-the-art UDA methods. The implementation code of CoTMix is available at \href{https://github.com/emadeldeen24/CoTMix}{github.com/emadeldeen24/CoTMix}.
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学习时间序列表示只有未标记的数据或几个标签样本可用时,可能是一项具有挑战性的任务。最近,通过对比,通过对比的不同数据观点从未标记的数据中提取有用的表示形式方面,对对比的自我监督学习表现出了很大的改进。在这项工作中,我们通过时间和上下文对比(TS-TCC)提出了一个新颖的时间序列表示学习框架,该框架从未标记的数据中学习了具有对比性学习的无标记数据的表示。具体而言,我们建议时间序列特定的弱和强大的增强,并利用他们的观点在拟议的时间对比模块中学习稳健的时间关系,除了通过我们提出的上下文对比模块学习判别性表示。此外,我们对时间序列数据增强选择进行系统研究,这是对比度学习的关键部分。我们还将TS-TCC扩展到了半监督的学习设置,并提出了一种类感知的TS-TCC(CA-TCC),从可用的少数标​​记数据中受益,以进一步改善TS-TCC学到的表示。具体而言,我们利用TS-TCC生成的强大伪标签来实现班级感知的对比损失。广泛的实验表明,对我们提议的框架所学的功能的线性评估与完全监督的培训相当。此外,我们的框架在少数标记的数据和转移学习方案中显示出高效率。该代码可在\ url {https://github.com/emadeldeen24/ts-tcc}上公开获得。
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域的概括方法旨在学习使用有限数量的源域,在训练过程中无需访问目标域样本的数据,以学习强大的域移动模型。用于域概括的流行域对齐方法寻求通过最大程度地降低所有域的特征分布之间的差异来提取域不变特征,从而无视域间关系。在本文中,我们提出了一种新颖的表示学习方法,该方法有选择地强制估计密切相关的源域之间的预测一致性。具体而言,我们假设域共享不同的类信息表示形式,因此,我们仅适用于所有可能导致负转移的域,而是正规化与密切相关域之间的差异。我们将我们的方法应用于时间序列分类任务,并在三个公共现实世界数据集上进行全面的实验。与最先进的方法相比,在准确性和模型校准方面,我们的方法比基线大大改善了基线,并取得更好或竞争性的性能。
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无监督域适应(UDA)已成功解决了可视应用程序的域移位问题。然而,由于以下原因,这些方法可能对时间序列数据的性能有限。首先,它们主要依赖于用于源预制的大规模数据集(即,ImageNet),这不适用于时间序列数据。其次,它们在域对齐步骤期间忽略源极限和目标域的特征空间上的时间维度。最后,最先前的UDA方法中的大多数只能对齐全局特征而不考虑目标域的细粒度分布。为了解决这些限制,我们提出了一个自我监督的自回归域适应(Slarda)框架。特别是,我们首先设计一个自我监督的学习模块,它利用预测作为辅助任务以提高源特征的可转换性。其次,我们提出了一种新的自回归域自适应技术,其包括在域对齐期间源和目标特征的时间依赖性。最后,我们开发了一个集合教师模型,通过自信的伪标记方法对准目标域中的类明智分发。已经在三个现实世界时间序列应用中进行了广泛的实验,具有30个跨域方案。结果表明,我们所提出的杆状方法明显优于时序序列域适应的最先进的方法。
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睡眠分期在诊断和治疗睡眠障碍中非常重要。最近,已经提出了许多数据驱动的深度学习模型,用于自动睡眠分期。他们主要在一个大型公共标签的睡眠数据集上训练该模型,并在较小的主题上对其进行测试。但是,他们通常认为火车和测试数据是从相同的分布中绘制的,这可能在现实世界中不存在。最近已经开发了无监督的域适应性(UDA)来处理此域移位问题。但是,以前用于睡眠分期的UDA方法具有两个主要局限性。首先,他们依靠一个完全共享的模型来对齐,该模型可能会在功能提取过程中丢失特定于域的信息。其次,它们仅在全球范围内将源和目标分布对齐,而无需考虑目标域中的类信息,从而阻碍了测试时模型的分类性能。在这项工作中,我们提出了一个名为Adast的新型对抗性学习框架,以解决未标记的目标域中的域转移问题。首先,我们开发了一个未共享的注意机制,以保留两个领域中的域特异性特征。其次,我们设计了一种迭代自我训练策略,以通过目标域伪标签提高目标域上的分类性能。我们还建议双重分类器,以提高伪标签的鲁棒性和质量。在六个跨域场景上的实验结果验证了我们提出的框架的功效及其优于最先进的UDA方法。源代码可在https://github.com/emadeldeen24/adast上获得。
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The field of autonomous mobile robots has undergone dramatic advancements over the past decades. Despite achieving important milestones, several challenges are yet to be addressed. Aggregating the achievements of the robotic community as survey papers is vital to keep the track of current state-of-the-art and the challenges that must be tackled in the future. This paper tries to provide a comprehensive review of autonomous mobile robots covering topics such as sensor types, mobile robot platforms, simulation tools, path planning and following, sensor fusion methods, obstacle avoidance, and SLAM. The urge to present a survey paper is twofold. First, autonomous navigation field evolves fast so writing survey papers regularly is crucial to keep the research community well-aware of the current status of this field. Second, deep learning methods have revolutionized many fields including autonomous navigation. Therefore, it is necessary to give an appropriate treatment of the role of deep learning in autonomous navigation as well which is covered in this paper. Future works and research gaps will also be discussed.
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We introduce a machine-learning (ML)-based weather simulator--called "GraphCast"--which outperforms the most accurate deterministic operational medium-range weather forecasting system in the world, as well as all previous ML baselines. GraphCast is an autoregressive model, based on graph neural networks and a novel high-resolution multi-scale mesh representation, which we trained on historical weather data from the European Centre for Medium-Range Weather Forecasts (ECMWF)'s ERA5 reanalysis archive. It can make 10-day forecasts, at 6-hour time intervals, of five surface variables and six atmospheric variables, each at 37 vertical pressure levels, on a 0.25-degree latitude-longitude grid, which corresponds to roughly 25 x 25 kilometer resolution at the equator. Our results show GraphCast is more accurate than ECMWF's deterministic operational forecasting system, HRES, on 90.0% of the 2760 variable and lead time combinations we evaluated. GraphCast also outperforms the most accurate previous ML-based weather forecasting model on 99.2% of the 252 targets it reported. GraphCast can generate a 10-day forecast (35 gigabytes of data) in under 60 seconds on Cloud TPU v4 hardware. Unlike traditional forecasting methods, ML-based forecasting scales well with data: by training on bigger, higher quality, and more recent data, the skill of the forecasts can improve. Together these results represent a key step forward in complementing and improving weather modeling with ML, open new opportunities for fast, accurate forecasting, and help realize the promise of ML-based simulation in the physical sciences.
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Low Earth Orbit (LEO) constellations, each comprising a large number of satellites, have become a new source of big data "from the sky". Downloading such data to a ground station (GS) for big data analytics demands very high bandwidth and involves large propagation delays. Federated Learning (FL) offers a promising solution because it allows data to stay in-situ (never leaving satellites) and it only needs to transmit machine learning model parameters (trained on the satellites' data). However, the conventional, synchronous FL process can take several days to train a single FL model in the context of satellite communication (Satcom), due to a bottleneck caused by straggler satellites. In this paper, we propose an asynchronous FL framework for LEO constellations called AsyncFLEO to improve FL efficiency in Satcom. Not only does AsynFLEO address the bottleneck (idle waiting) in synchronous FL, but it also solves the issue of model staleness caused by straggler satellites. AsyncFLEO utilizes high-altitude platforms (HAPs) positioned "in the sky" as parameter servers, and consists of three technical components: (1) a ring-of-stars communication topology, (2) a model propagation algorithm, and (3) a model aggregation algorithm with satellite grouping and staleness discounting. Our extensive evaluation with both IID and non-IID data shows that AsyncFLEO outperforms the state of the art by a large margin, cutting down convergence delay by 22 times and increasing accuracy by 40%.
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A Complete Computer vision system can be divided into two main categories: detection and classification. The Lane detection algorithm is a part of the computer vision detection category and has been applied in autonomous driving and smart vehicle systems. The lane detection system is responsible for lane marking in a complex road environment. At the same time, lane detection plays a crucial role in the warning system for a car when departs the lane. The implemented lane detection algorithm is mainly divided into two steps: edge detection and line detection. In this paper, we will compare the state-of-the-art implementation performance obtained with both FPGA and GPU to evaluate the trade-off for latency, power consumption, and utilization. Our comparison emphasises the advantages and disadvantages of the two systems.
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Automatic segmentation is essential for the brain tumor diagnosis, disease prognosis, and follow-up therapy of patients with gliomas. Still, accurate detection of gliomas and their sub-regions in multimodal MRI is very challenging due to the variety of scanners and imaging protocols. Over the last years, the BraTS Challenge has provided a large number of multi-institutional MRI scans as a benchmark for glioma segmentation algorithms. This paper describes our contribution to the BraTS 2022 Continuous Evaluation challenge. We propose a new ensemble of multiple deep learning frameworks namely, DeepSeg, nnU-Net, and DeepSCAN for automatic glioma boundaries detection in pre-operative MRI. It is worth noting that our ensemble models took first place in the final evaluation on the BraTS testing dataset with Dice scores of 0.9294, 0.8788, and 0.8803, and Hausdorf distance of 5.23, 13.54, and 12.05, for the whole tumor, tumor core, and enhancing tumor, respectively. Furthermore, the proposed ensemble method ranked first in the final ranking on another unseen test dataset, namely Sub-Saharan Africa dataset, achieving mean Dice scores of 0.9737, 0.9593, and 0.9022, and HD95 of 2.66, 1.72, 3.32 for the whole tumor, tumor core, and enhancing tumor, respectively. The docker image for the winning submission is publicly available at (https://hub.docker.com/r/razeineldin/camed22).
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