有很好的参数来支持声明，特征表示最终从一般到深度神经网络（DNN）的特定转换，但这种转变仍然相对缺乏缺陷。在这项工作中，我们向理解特征表示的转换来移动一个微小的步骤。我们首先通过分析中间层中的类分离，然后将类别分离过程作为动态图中的社区演变进行了描述。然后，我们介绍模块化，是图形理论中的常见度量，量化社区的演变。我们发现，随着层更深，而是下降或达到特定层的高原，模块化趋于上升。通过渐近分析，我们表明模块化可以提供对特征表示转换的定量分析。通过了解特征表示，我们表明模块化也可用于识别和定位DNN中的冗余层，这为图层修剪提供了理论指导。基于这种鼓舞人心的发现，我们提出了一种基于模块化的层面修剪方法。进一步的实验表明，我们的方法可以修剪冗余层，对性能的影响最小。该代码可在https://github.com/yaolu-zjut/dynamic-graphs-construction中获得。

FDG-PET揭示了具有轻度认知障碍（MCI）和Alzheimer疾病（AD）的个体的脑代谢改变。通过计算机辅助诊断（CAD）技术源自FDG-PET的一些生物标志物已被证明可以准确诊断正常控制（NC），MCI和AD。然而，使用FDG-PET图像鉴定早期MCI（EMCI）和晚期MCI（LMCI）的研究仍然不足。与基于FMRI和DTI图像的研究相比，FDG-PET图像中区域间表示特征的研究不足。此外，考虑到不同个体的可变性，一些与两个类非常相似的硬样品限制了分类性能。为了解决这些问题，本文提出了一种新的双线性池和度量学习网络（BMNet），其可以通过构造嵌入空间来提取区域间表示特征并区分硬样品。为了验证所提出的方法，我们从ADNI收集998个FDG-PET图像。在常见的预处理步骤之后，根据自动解剖地标（AAL）模板从每个FDG-PET图像中提取90个特征，然后被发送到所提出的网络。对多种两类分类进行了广泛的5倍交叉验证实验。实验表明，在向基线模型中添加双线性池模块和度量损耗后，大多数度量都会得到改善。具体而言，在EMCI和LMCI之间的分类任务中，在添加三维度量损失后，特异性提高了6.38％，并且使用双线性池模块后，负预测值（NPV）在3.45％后提高了3.45％。

轻量级模型设计已成为应用深度学习技术的重要方向，修剪是实现模型参数和拖鞋的大量减少的有效均值。现有的神经网络修剪方法主要从参数的重要性开始，以及设计参数评估度量来迭代地执行参数修剪。这些方法不是从模型拓扑的角度研究的，可能是有效但不高效的，并且需要完全不同的不同数据集修剪。在本文中，我们研究了神经网络的图形结构，并提出了常规的基于图的修剪（RGP）来执行单次神经网络修剪。我们生成常规图，将图的节点度值设置为满足修剪比率，并通过将边缘交换以获得最佳边缘分布来降低曲线图的平均最短路径长度。最后，将获得的图形映射到神经网络结构中以实现修剪。实验表明，曲线图的平均最短路径长度与相应神经网络的分类精度负相关，所提出的RGP显示出强的精度保持能力，具有极高的参数减少（超过90％）和拖鞋（更多超过90％）。

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.

As one of the most important psychic stress reactions, micro-expressions (MEs), are spontaneous and transient facial expressions that can reveal the genuine emotions of human beings. Thus, recognizing MEs (MER) automatically is becoming increasingly crucial in the field of affective computing, and provides essential technical support in lie detection, psychological analysis and other areas. However, the lack of abundant ME data seriously restricts the development of cutting-edge data-driven MER models. Despite the recent efforts of several spontaneous ME datasets to alleviate this problem, it is still a tiny amount of work. To solve the problem of ME data hunger, we construct a dynamic spontaneous ME dataset with the largest current ME data scale, called DFME (Dynamic Facial Micro-expressions), which includes 7,526 well-labeled ME videos induced by 671 participants and annotated by more than 20 annotators throughout three years. Afterwards, we adopt four classical spatiotemporal feature learning models on DFME to perform MER experiments to objectively verify the validity of DFME dataset. In addition, we explore different solutions to the class imbalance and key-frame sequence sampling problems in dynamic MER respectively on DFME, so as to provide a valuable reference for future research. The comprehensive experimental results show that our DFME dataset can facilitate the research of automatic MER, and provide a new benchmark for MER. DFME will be published via https://mea-lab-421.github.io.