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arXiv 2022年

作者： Zhao, Zhilin Cao, Longbing Wan, Yuanyu School of Computer Science and Engineering Sun Yat-sen University Guangzhou China School of Computing Macquarie University Sydney Australia Key Laboratory of Machine Intelligence and Advanced Computing Ministry of Education China School of Software Technology Zhejiang University Ningbo China

We consider a general and realistic scenario involving nonstationary time series, consisting of several offline intervals with different distributions within a fixed offline time horizon, and an online interval that continuously receives new samples. For non-stationary time series, the data distribution in the current online interval may have appeared in previous offline intervals. We theoretically explore the feasibility of applying knowledge from offline intervals to the current online interval. To this end, we propose the Mixture of Online and Offline Experts (MOOE). MOOE learns static offline experts from offline intervals and maintains a dynamic online expert for the current online interval. It then adaptively combines the offline and online experts using a meta expert to make predictions for the samples received in the online interval. Specifically, we focus on theoretical analysis, deriving parameter convergence, regret bounds, and generalization error bounds to prove the effectiveness of the algorithm. Copyright © 2022, The Authors. All rights reserved.

关键词： Time series

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Task-oriented Self-supervised Learning for Anomaly Detection in Electroencephalography

arXiv

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arXiv 2022年

作者： Zheng, Yaojia Liu, Zhouwu Mo, Rong Chen, Ziyi Zheng, Wei-Shi Wang, Ruixuan School of Computer Science and Engineering Sun Yat-sen University China Key Laboratory of Machine Intelligence and Advanced Computing MOE China The First Affiliated Hospital Sun Yat-sen University Guangzhou China

Accurate automated analysis of electroencephalography (EEG) would largely help clinicians effectively monitor and diagnose patients with various brain diseases. Compared to supervised learning with labelled disease EEG data which can train a model to analyze specific diseases but would fail to monitor previously unseen statuses, anomaly detection based on only normal EEGs can detect any potential anomaly in new EEGs. Different from existing anomaly detection strategies which do not consider any property of unavailable abnormal data during model development, a task-oriented self-supervised learning approach is proposed here which makes use of available normal EEGs and expert knowledge about abnormal EEGs to train a more effective feature extractor for the subsequent development of anomaly detector. In addition, a specific two-branch convolutional neural network with larger kernels is designed as the feature extractor such that it can more easily extract both larger-scale and small-scale features which often appear in unavailable abnormal EEGs. The effectively designed and trained feature extractor has shown to be able to extract better feature representations from EEGs for development of anomaly detector based on normal data and future anomaly detection for new EEGs, as demonstrated on three EEG datasets. The code is available at https://***/ironing/EEG-AD. © 2022, CC BY.

关键词： Electroencephalography

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Adversarial Domain Adaptation Network with Enhanced Feature Discriminability for Thyroid Ultrasound Images

Adversarial Domain Adaptation Network with Enhanced Feature ...

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International Joint Conference on Neural Networks (IJCNN)

作者： Xuewei Li Pinjie Li Ruixuan Zhang Chenhan Wang Xi Wei Mankun Zhao College of Intelligence and Computing Tianjin University Tianjin China Tianjin Key Laboratory of Cognitive Computing and Application Tianjin China Tianjin Key Laboratory of Advanced Networking Tianjin China Tianjin International Engineering Institute Tianjin University Tianjin China OpenBayes (Tianjin) IT Co. Ltd. Tianjin China Department of Diagnostic and Therapeutic Ultrasonography Tianjin Medical University Cancer Institute and Hospital Tianjin China

In recent years, computer-aided diagnosis technology has made breakthroughs in clinical medicine. However, due to the different models and configurations of ultrasound instruments, the thyroid ultrasound images collected by different medical centers have different visual characteristics. It leads to domain shift in multi-center data and the lower generalization of computer-aided diagnosis models. We consider this limitation may attribute to the minor inter-class differences in thyroid ultrasound images, resulting in confusion space before and after domain feature alignment. Therefore, we propose an adversarial domain adaptation network with enhanced feature discriminability method. Among them, the discriminative feature learning module strengthens the discriminability of the learned features, so that the class distribution in each domain presents a high cohesion and low coupling effect; the class alignment module reduces the distance between the same class samples across domains to achieve class alignment and further strengthen the discriminability of each class. Experiments show that our method outperforms other state-of-the-art algorithms on the internal thyroid ultrasound image dataset. The method can effectively improve the model's generalization ability on multi-center thyroid ultrasound images.

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IDPL: Intra-subdomain adaptation adversarial learning segmentation method based on Dynamic Pseudo Labels

arXiv

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arXiv 2022年

作者： Li, Xuewei Zhang, Weilun Zhao, Mankun Li, Ming Yan, Yang Yu, Jian College of Intelligence and Computing Tianjin University Tianjin China Tianjin Key Laboratory of Cognitive Computing and Application Tianjin China Tianjin Key Laboratory of Advanced Networking Tianjin China Tianjin International Engineering Institute Tianjin University Tianjin China Tianjin Medical University General Hospital Tianjin China

Unsupervised domain adaptation(UDA) has been applied to image semantic segmentation to solve the problem of domain offset. However, in some difficult categories with poor recognition accuracy, the segmentation effects are still not ideal. To this end, in this paper, Intra-subdomain adaptation adversarial learning segmentation method based on Dynamic Pseudo Labels(IDPL) is proposed. The whole process consists of 3 steps: Firstly, the instance-level pseudo label dynamic generation module is proposed, which fuses the class matching information in global classes and local instances, thus adaptively generating the optimal threshold for each class, obtaining high-quality pseudo labels. Secondly, the subdomain classifier module based on instance confidence is constructed, which can dynamically divide the target domain into easy and difficult subdomains according to the relative proportion of easy and difficult instances. Finally, the subdomain adversarial learning module based on self-attention is proposed. It uses multi-head self-attention to confront the easy and difficult subdomains at the class level with the help of generated high-quality pseudo labels, so as to focus on mining the features of difficult categories in the high-entropy region of target domain images, which promotes class-level conditional distribution alignment between the subdomains, improving the segmentation performance of difficult categories. For the difficult categories, the experimental results show that the performance of IDPL is significantly improved compared with other latest mainstream methods. Copyright © 2022, The Authors. All rights reserved.

关键词： Semantic Segmentation

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A Novel Duo-Stage driven Deep Neural Network Approach for Mitigating Electrode Shift Impact on Myoelectric Pattern Recognition Systems

A Novel Duo-Stage driven Deep Neural Network Approach for Mi...

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IEEE International Workshop on Medical Measurement and Applications (MEMEA)

作者： Frank Kulwa Oluwarotimi Williams Samuel Mojisola Grace Asogbon Tolulope Tofunmi Oyemakinde Olumide Olayinka Obe Guanglin Li CAS Key Laboratory of Human-Machine Intelligence-Synergy Systems Shenzhen Institute of Artificial Intelligence and Robotics for Society Shenzhen Institute of Advanced Technology (SIAT) Chinese Academy of Sciences (CAS) Shenzhen Guangdong China Shenzhen College of Advanced Technology University of Chinese Academy of Sciences Shenzhen Guangdong China School of Computing and Engineering University of Derby Derby United Kingdom Department of Computer Science Federal University of Technology Akure Nigeria

A major barrier to the commercialization of pattern recognition (PR)-based myoelectric prostheses is the lack of robustness to confounding factors such as electrode shift which has been lingering for years. To overcome this challenge, a novel Duo-Stage Convolutional Neural Network (DS-CNN) is proposed. The DS-CNN is comprised of two cascaded stages in which the first stage deciphers the occurrence of a particular kind of shift upon which a requisite CNN model is triggered in the second stage for accurate decoding of individual motion intent, which is necessary for initiating robust control of the prostheses. The proposed scheme works on raw EMG signals as input which reduces the preprocessing time that would be required in conventional machine learning-based PR schemes, to effectively mitigate both transverse and longitudinal shifts using the same network architecture. This approach was validated for four distinct electrode shift conditions (with shifts in the range of 7.50mm-10.05mm) in a dataset obtained from 18 able-bodied subjects that performed 8 classes of targeted hand gestures. The experimental results show that the proposed dual-stage driven deep neural network model can adequately resolve the effects of electrode shift with classification accuracy near the No-shift scenario (< 1.70% difference between shift mitigation and No shift scenarios). These outcomes suggest that our method can provide a practical solution for adaptation to electrode shift, thus improving the robustness of the EMG pattern recognition systems in both clinical and commercial settings.

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A Multilevel Approach for Solving Large-Scale QUBO Problems with Noisy Hybrid Quantum Approximate Optimization

A Multilevel Approach for Solving Large-Scale QUBO Problems ...

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IEEE Conference on High Performance Extreme computing (HPEC)

作者： Filip B. Maciejewski Bao G. Bach Maxime Dupont P. Aaron Lott Bhuvanesh Sundar David E. Bernal Neira Ilya Safro Davide Venturelli Quantum Artificial Intelligence Laboratory (QuAIL) NASA Ames Research Center CA USA USRA Research Institute for Advanced Computer Science (RIACS) CA USA Department of Computer and Information Sciences University of Delaware Newark DE USA Rigetti Computing Berkeley CA Davidson School of Chemical Engineering Purdue University West Lafayette IN USA

ISBN: (数字)9798350387131

ISBN: (纸本)9798350387148

Quantum approximate optimization is one of the promising candidates for useful quantum computation, particularly in the context of finding approximate solutions to Quadratic Unconstrained Binary Optimization (QUBO) problems. However, the existing quantum processing units (QPUs) are of relatively small size, and canonical mappings of QUBO via the Ising model require one qubit per variable, rendering direct large-scale optimization infeasible. In classical optimization, a general strategy for addressing many large-scale problems is via multilevel/multigrid methods, where the large target problem is iteratively coarsened and the global solution is constructed from multiple small-scale optimization runs. In this work, we experimentally test how existing QPUs perform when used as a sub-solver within such a multilevel strategy. To this aim, we combine and extend (via additional classical processing steps) the recently proposed Noise-Directed Adaptive Remapping (NDAR) and Quantum Relax & Round (QRR) algorithms. We first demonstrate the effectiveness of our heuristic extensions on Rigetti's superconducting transmon device Ankaa-2. We find approximate solutions to 10 instances of fully connected 82-qubit Sherrington-Kirkpatrick graphs with random integer-valued coefficients obtaining normalized approximation ratios (ARs) in the range $\sim 0.98-1.0$ , and the same class with real-valued coefficients (ARs $\sim 0.94-1.0)$ . Then, we implement the extended NDAR and QRR algorithms as subsolvers in the multilevel algorithm for 6 large-scale graphs with at most $\sim 27,000$ variables. In practice, the QPU (with classical post-processing steps) is used to find approximate solutions to dozens of at most 82-qubit problems, which are iteratively used to construct the global solution. We observe that quantum optimization results are competitive in terms of the quality of solutions when compared to classical heuristics used as subsolvers within the multilevel approach. Reproducibility

关键词： Superconducting devices Performance evaluation Quantum advantage Source coding Qubit Pipelines Approximation algorithms Rendering (computer graphics) Noise measurement Optimization

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Restricted Black-box Adversarial Attack Against DeepFake Face Swapping

arXiv

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arXiv 2022年

作者： Dong, Junhao Wang, Yuan Lai, Jianhuang Xie, Xiaohua School of Computer Science and Engineering Sun Yat-sen University Guangzhou510006 China Key Laboratory of Machine Intelligence and Advanced Computing Ministry of Education Guangzhou510006 China Guangdong Key Laboratory of Information Security Technology Guangzhou510006 China

DeepFake face swapping presents a significant threat to online security and social media, which can replace the source face in an arbitrary photo/video with the target face of an entirely different person. In order to prevent this fraud, some researchers have begun to study the adversarial methods against DeepFake or face manipulation. However, existing works focus on the white-box setting or the black-box setting driven by abundant queries, which severely limits the practical application of these methods. To tackle this problem, we introduce a practical adversarial attack that does not require any queries to the facial image forgery model. Our method is built on a substitute model persuing for face reconstruction and then transfers adversarial examples from the substitute model directly to inaccessible black-box DeepFake models. Specially, we propose the Transferable Cycle Adversary Generative Adversarial Network (TCA-GAN) to construct the adversarial perturbation for disrupting unknown DeepFake systems. We also present a novel post-regularization module for enhancing the transferability of generated adversarial examples. To comprehensively measure the effectiveness of our approaches, we construct a challenging benchmark of DeepFake adversarial attacks for future development. Extensive experiments impressively show that the proposed adversarial attack method makes the visual quality of DeepFake face images plummet so that they are easier to be detected by humans and algorithms. Moreover, we demonstrate that the proposed algorithm can be generalized to offer face image protection against various face translation methods. © 2022, CC BY.

关键词： Generative adversarial networks

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An Attention-based Bidirectional LSTM Model for Continuous Cross-Subject Estimation of Knee Joint Angle during Running from sEMG Signals

An Attention-based Bidirectional LSTM Model for Continuous C...

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： Alireza Rezaie Zangene Oluwarotimi Williams Samuel Ali Abbasi Kianoush Nazarpour Alistair A. McEwan Guanglin Li Department of Sports Biomechanics Kharazmi University Tehran Iran School of Computing and Engineering University of Derby United Kingdom Edinburgh Neuroprosthetics Laboratory School of Informatics The University of Edinburgh Edinburgh UK CAS Key Laboratory of Human-Machine Intelligence-Synergy Systems Shenzhen Institute of Advanced Technology Chinese Academy of Sciences (CAS) Shenzhen Guangdong China

Accurate and robust estimation of joint kinematics via surface electromyogram (sEMG) signals provides a human-machine interaction (HMI)-based method that can be used to adequately control rehabilitation robots while performing complex movements, such as running, for motor function restoration in affected individuals. To this end, this paper proposes a deep learning-based model (AM-BiLSTM) that integrates a bidirectional long short-term memory (BiLSTM) network and an attention mechanism (AM) for robust estimation of joint kinematics. The proposed model was appraised using knee joint kinematic and sEMG signals collected from fourteen subjects who performed running at the speed of 2 m/s. The proposed model's generalizability was tested for both within- and cross-subject scenarios and compared with long short-term memory (LSTM) and multi-layer perceptron (MLP) networks in terms of normalized root-mean-square error and correlation coefficient metrics. Based on the statistical tests, the proposed AM-BiLSTM model significantly outperformed the LSTM and MLP methods in both within- and cross-subject scenarios (p<0.05) and achieved state-of-the-art *** Relevance— The promising results of this study suggest that the AM-BiLSTM model has the potential for continuous cross-subject estimation of lower limb kinematics during running, which can be used to control sEMG-driven exoskeleton robots oriented towards rehabilitation training.

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Dual-Level Masked Semantic Inference for Semi-Supervised Semantic Segmentation

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IEEE Transactions on Multimedia 2025年

作者： Ma, Qiankun Zhang, Ziyao Qiao, Pengchong Wang, Yu Ji, Rongrong Liu, Chang Chen, Jie Peking University School of Electronic and Computer Engineering Shenzhen518055 China Chinese Academy of Sciences Paul C. Lauterbur Research Center for Biomedical Imaging Shenzhen Institutes of Advanced Technology Shenzhen518055 China University of the Chinese Academy of Sciences Beijing100049 China Peng Cheng Laboratory Shenzhen518055 China Xiamen University Media Analytics and Computing Laboratory Department of Artificial Intelligence School of Informatics Xiamen361005 China Tsinghua University Department of Automation Beijing100084 China

Semi-supervised semantic segmentation pursues a holistic pixel-wise understanding of unseen images with limited annotation. To this end, existing methods focus on regularizing per-pixel prediction consistency within unlabeled data, while rarely modeling contextual relationships. But in fact, contextual semantics can provide valuable clues for scene understanding like inner-object continuity and spatial relationships' causality. Thus, in this paper, we propose a Dual-level Masked Semantics Inference (DMSI) that takes the initiative to explicitly learn contextual relationships via enforcing our model to infer the semantics of a pixel according to its surrounding contexts. This allows our model to exhaust accurate semantics by incorporating inter-pixel context clues, further leading to comprehensive segmentation. Specifically, DMSI comprises two main components: 1) Dual-level mask consistency regularization (DMCR) that learns the ability of semantics inference by aligning the predictions of masked views with the prediction of the complete view. The masked views here come from both the image level and feature level, where our model captures low-level attributes and high-level representations respectively. 2) AdaMask that provides a proper mask position and ratio for each image, guiding our model to focus on semantic-rich regions while providing balanced training between hard and easy samples. Through learning the ability of semantic inferring, DMSI remarkably enhances the interaction between pixels, further progressively intensifying the understanding of semantics. Extensive experiments under various settings on Cityscapes and Pascal VOC 2012 show that DMSI achieves new state-of-the-art performances. Furthermore, analysis indicates that our method has superiority in mining inter-pixel semantic relationships and improving robustness facing noise corruption. © 1999-2012 IEEE.

关键词： Latent semantic analysis

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Koopman Neural Operator as a Mesh-Free Solver of Non-Linear Partial Differential Equations

SSRN

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SSRN 2023年

作者： Xiong, Wei Huang, Xiaomeng Zhang, Ziyang Deng, Ruixuan Sun, Pei Tian, Yang Department of Earth System Science Tsinghua University Beijing100084 China Department of Psychology Tsinghua Laboratory of Brain and Intelligence Tsinghua University Beijing100084 China Department of Biomedical Engineering Tsinghua University Beijing100084 China Laboratory of Advanced Computing and Storage Central Research Institute Laboratories Huawei Technologies Co. Ltd 2012 China

The lacking of analytic solutions of diverse partial differential equations (PDEs) gives birth to a series of computational techniques for numerical solutions. Although numerous latest advances are accomplished in developing neural operators, a kind of neural-network-based PDE solver, these solvers become less accurate and explainable while learning long-term behaviors of non-linear PDE families. In this paper, we propose Koopman neural operator (KNO), a new neural operator, to overcome these challenges. With the same objective of learning an infinite-dimensional mapping between Banach spaces that serves as the solution operator of the target PDE family, our approach differs from existing models by formulating a non-linear dynamic system of equation solution. By approximating the Koopman operator, an infinite-dimensional operator governing all possible observations of the dynamic system, to act on the flow mapping of the dynamic system, we can equivalently learn the solution of a non-linear PDE family by solving simple linear prediction problems. In zero-shot prediction and long-term prediction experiments on representative PDEs (e.g., the Navier-Stokes equation), KNO exhibits notable advantages in breaking the tradeoff between accuracy and efficiency (e.g., model size) while previous state-of-the-art models are limited. These results suggest the potential of KNO in supporting diverse science and engineering applications. © 2023, The Authors. All rights reserved.

关键词： Partial differential equations

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