Federated learning (FL) has been recognized as a privacy-preserving distributed machine learning paradigm that enables knowledge sharing among various heterogeneous artificial intelligence (AIoT) devices through centralized global model aggregation. FL suffers from model inaccuracy and slow convergence due to the model heterogeneity of the AIoT devices involved. Although various existing methods try to solve the bottleneck of the model heterogeneity problem, most of them improve the accuracy of heterogeneous models in a coarse-grained manner, which makes it still a great challenge to deploy large-scale AIoT devices. To alleviate the negative impact of this problem and take full advantage of the diversity of each heterogeneous model, we propose an efficient framework named HierarchyFL, which uses a small amount of public data for efficient and scalable knowledge across a variety of differently structured models. By using self-distillation and our proposed ensemble library, each hierarchical model can intelligently learn from each other on cloud servers. Experimental results on various well-known datasets show that HierarchyFL can not only maximize the knowledge sharing among various heterogeneous models in large-scale AIoT systems, but also greatly improve the model performance of each involved heterogeneous AIoT device.

作为一种有希望的隐私机器学习方法，联合学习（FL）可以使客户跨客户培训，而不会损害其机密的本地数据。但是，现有的FL方法遇到了不均分布数据的推理性能低的问题，因为它们中的大多数依赖于联合平均（FIDAVG）基于联合的聚合。通过以粗略的方式平均模型参数，FedAvg将局部模型的个体特征黯然失色，这极大地限制了FL的推理能力。更糟糕的是，在每一轮FL培训中，FedAvg向客户端向客户派遣了相同的初始本地模型，这很容易导致对最佳全局模型的局限性搜索。为了解决上述问题，本文提出了一种新颖有效的FL范式，名为FEDMR（联合模型重组）。与传统的基于FedAvg的方法不同，FEDMR的云服务器将收集到的本地型号的每一层层混合，并重组它们以实现新的模型，以供客户端培训。由于在每场FL比赛中进行了细粒度的模型重组和本地培训，FEDMR可以迅速为所有客户找出一个全球最佳模型。全面的实验结果表明，与最先进的FL方法相比，FEDMR可以显着提高推理准确性而不会引起额外的通信开销。

作为一个有前途的分布式机器学习范式，联合学习（FL）在不影响用户隐私的情况下培训具有分散数据的中央模型，这使得其被人工智能互联网（AIT）应用程序广泛使用。然而，传统的流体遭受了模型不准确，因为它会使用数据硬标签培训本地模型，并忽略与小概率不正确的预测的有用信息。虽然各种解决方案尽量解决传统流域的瓶颈，但大多数人都引入了显着的通信和记忆开销，使大规模的AIOT设备部署成为一个巨大的挑战。为了解决上述问题，本文提出了一种基于蒸馏的新型联合学习（DFL）架构，可实现AIT应用的高效准确。灵感来自知识蒸馏（KD），可以提高模型准确性，我们的方法将KD使用的软目标添加到FL模型培训，占用可忽略不计的网络资源。在每轮本地训练之后，通过每种充气设备的局部样品预测生成软目标，并用于下一轮模型训练。在DFL的本地培训期间，软目标和硬质标签都被用作模型预测的近似目标，以通过补充软目标的知识来提高模型准确性。为了进一步提高DFL模型的性能，我们设计了一种动态调整策略，用于调整KD中使用的两个损耗功能的比率，这可以最大限度地利用软目标和硬质标签。众所周知的基准测试的全面实验结果表明，我们的方法可以显着提高独立和相同分布（IID）和非IID数据的FL的模型精度。

4D隐式表示中的最新进展集中在全球控制形状和运动的情况下，低维潜在向量，这很容易缺少表面细节和累积跟踪误差。尽管许多深层的本地表示显示了3D形状建模的有希望的结果，但它们的4D对应物尚不存在。在本文中，我们通过提出一个新颖的局部4D隐性代表来填补这一空白，以动态穿衣人，名为Lord，具有4D人类建模和局部代表的优点，并实现具有详细的表面变形的高保真重建，例如衣服皱纹。特别是，我们的主要见解是鼓励网络学习本地零件级表示的潜在代码，能够解释本地几何形状和时间变形。为了在测试时间进行推断，我们首先估计内部骨架运动在每个时间步中跟踪本地零件，然后根据不同类型的观察到的数据通过自动编码来优化每个部分的潜在代码。广泛的实验表明，该提出的方法具有强大的代表4D人类的能力，并且在实际应用上胜过最先进的方法，包括从稀疏点，非刚性深度融合（质量和定量）进行的4D重建。

Deep learning models can achieve high accuracy when trained on large amounts of labeled data. However, real-world scenarios often involve several challenges: Training data may become available in installments, may originate from multiple different domains, and may not contain labels for training. Certain settings, for instance medical applications, often involve further restrictions that prohibit retention of previously seen data due to privacy regulations. In this work, to address such challenges, we study unsupervised segmentation in continual learning scenarios that involve domain shift. To that end, we introduce GarDA (Generative Appearance Replay for continual Domain Adaptation), a generative-replay based approach that can adapt a segmentation model sequentially to new domains with unlabeled data. In contrast to single-step unsupervised domain adaptation (UDA), continual adaptation to a sequence of domains enables leveraging and consolidation of information from multiple domains. Unlike previous approaches in incremental UDA, our method does not require access to previously seen data, making it applicable in many practical scenarios. We evaluate GarDA on two datasets with different organs and modalities, where it substantially outperforms existing techniques.

The development of social media user stance detection and bot detection methods rely heavily on large-scale and high-quality benchmarks. However, in addition to low annotation quality, existing benchmarks generally have incomplete user relationships, suppressing graph-based account detection research. To address these issues, we propose a Multi-Relational Graph-Based Twitter Account Detection Benchmark (MGTAB), the first standardized graph-based benchmark for account detection. To our knowledge, MGTAB was built based on the largest original data in the field, with over 1.55 million users and 130 million tweets. MGTAB contains 10,199 expert-annotated users and 7 types of relationships, ensuring high-quality annotation and diversified relations. In MGTAB, we extracted the 20 user property features with the greatest information gain and user tweet features as the user features. In addition, we performed a thorough evaluation of MGTAB and other public datasets. Our experiments found that graph-based approaches are generally more effective than feature-based approaches and perform better when introducing multiple relations. By analyzing experiment results, we identify effective approaches for account detection and provide potential future research directions in this field. Our benchmark and standardized evaluation procedures are freely available at: https://github.com/GraphDetec/MGTAB.

As one of the prevalent methods to achieve automation systems, Imitation Learning (IL) presents a promising performance in a wide range of domains. However, despite the considerable improvement in policy performance, the corresponding research on the explainability of IL models is still limited. Inspired by the recent approaches in explainable artificial intelligence methods, we proposed a model-agnostic explaining framework for IL models called R2RISE. R2RISE aims to explain the overall policy performance with respect to the frames in demonstrations. It iteratively retrains the black-box IL model from the randomized masked demonstrations and uses the conventional evaluation outcome environment returns as the coefficient to build an importance map. We also conducted experiments to investigate three major questions concerning frames' importance equality, the effectiveness of the importance map, and connections between importance maps from different IL models. The result shows that R2RISE successfully distinguishes important frames from the demonstrations.

Compressed videos often exhibit visually annoying artifacts, known as Perceivable Encoding Artifacts (PEAs), which dramatically degrade video visual quality. Subjective and objective measures capable of identifying and quantifying various types of PEAs are critical in improving visual quality. In this paper, we investigate the influence of four spatial PEAs (i.e. blurring, blocking, bleeding, and ringing) and two temporal PEAs (i.e. flickering and floating) on video quality. For spatial artifacts, we propose a visual saliency model with a low computational cost and higher consistency with human visual perception. In terms of temporal artifacts, self-attention based TimeSFormer is improved to detect temporal artifacts. Based on the six types of PEAs, a quality metric called Saliency-Aware Spatio-Temporal Artifacts Measurement (SSTAM) is proposed. Experimental results demonstrate that the proposed method outperforms state-of-the-art metrics. We believe that SSTAM will be beneficial for optimizing video coding techniques.

We propose a distributionally robust return-risk model for Markov decision processes (MDPs) under risk and reward ambiguity. The proposed model optimizes the weighted average of mean and percentile performances, and it covers the distributionally robust MDPs and the distributionally robust chance-constrained MDPs (both under reward ambiguity) as special cases. By considering that the unknown reward distribution lies in a Wasserstein ambiguity set, we derive the tractable reformulation for our model. In particular, we show that that the return-risk model can also account for risk from uncertain transition kernel when one only seeks deterministic policies, and that a distributionally robust MDP under the percentile criterion can be reformulated as its nominal counterpart at an adjusted risk level. A scalable first-order algorithm is designed to solve large-scale problems, and we demonstrate the advantages of our proposed model and algorithm through numerical experiments.

Witnessing the impressive achievements of pre-training techniques on large-scale data in the field of computer vision and natural language processing, we wonder whether this idea could be adapted in a grab-and-go spirit, and mitigate the sample inefficiency problem for visuomotor driving. Given the highly dynamic and variant nature of the input, the visuomotor driving task inherently lacks view and translation invariance, and the visual input contains massive irrelevant information for decision making, resulting in predominant pre-training approaches from general vision less suitable for the autonomous driving task. To this end, we propose PPGeo (Policy Pre-training via Geometric modeling), an intuitive and straightforward fully self-supervised framework curated for the policy pretraining in visuomotor driving. We aim at learning policy representations as a powerful abstraction by modeling 3D geometric scenes on large-scale unlabeled and uncalibrated YouTube driving videos. The proposed PPGeo is performed in two stages to support effective self-supervised training. In the first stage, the geometric modeling framework generates pose and depth predictions simultaneously, with two consecutive frames as input. In the second stage, the visual encoder learns driving policy representation by predicting the future ego-motion and optimizing with the photometric error based on current visual observation only. As such, the pre-trained visual encoder is equipped with rich driving policy related representations and thereby competent for multiple visuomotor driving tasks. Extensive experiments covering a wide span of challenging scenarios have demonstrated the superiority of our proposed approach, where improvements range from 2% to even over 100% with very limited data. Code and models will be available at https://github.com/OpenDriveLab/PPGeo.