In this work, we devise robust and efficient learning protocols for orchestrating a Federated Learning (FL) process for the Federated Tumor Segmentation Challenge (FeTS 2022). Enabling FL for FeTS setup is challenging mainly due to data heterogeneity among collaborators and communication cost of training. To tackle these challenges, we propose Robust Learning Protocol (RoLePRO) which is a combination of server-side adaptive optimisation (e.g., server-side Adam) and judicious parameter (weights) aggregation schemes (e.g., adaptive weighted aggregation). RoLePRO takes a two-phase approach, where the first phase consists of vanilla Federated Averaging, while the second phase consists of a judicious aggregation scheme that uses a sophisticated reweighting, all in the presence of an adaptive optimisation algorithm at the server. We draw insights from extensive experimentation to tune learning rates for the two phases.
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在联合学习(FL)中,已经开发出强大的聚合方案来防止恶意客户。许多强大的聚合方案依赖于某些数量的良性客户端存在于工人的仲裁中。当客户端可以加入WILL或基于空闲系统状态等因素时,这可能很难保证,并连接到电源和WiFi。我们解决在犯罪者可能完全恶意时,解决对抗对抗训练的保护的场景。我们模拟了一种攻击者,攻击模型将弱点插入对抗培训,使得该模型显示出明显的对抗性鲁棒性,而攻击者可以利用插入的弱点来绕过对抗性训练并强迫模型错误分类对抗性示例。我们使用抽象的解释技术来检测此类隐秘攻击并阻止损坏的模型更新。我们表明,即使对适应性攻击者,这种防御也可以保持对抗性鲁棒性。
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Graph Neural Networks (GNNs) achieve state-of-the-art performance on graph-structured data across numerous domains. Their underlying ability to represent nodes as summaries of their vicinities has proven effective for homophilous graphs in particular, in which same-type nodes tend to connect. On heterophilous graphs, in which different-type nodes are likely connected, GNNs perform less consistently, as neighborhood information might be less representative or even misleading. On the other hand, GNN performance is not inferior on all heterophilous graphs, and there is a lack of understanding of what other graph properties affect GNN performance. In this work, we highlight the limitations of the widely used homophily ratio and the recent Cross-Class Neighborhood Similarity (CCNS) metric in estimating GNN performance. To overcome these limitations, we introduce 2-hop Neighbor Class Similarity (2NCS), a new quantitative graph structural property that correlates with GNN performance more strongly and consistently than alternative metrics. 2NCS considers two-hop neighborhoods as a theoretically derived consequence of the two-step label propagation process governing GCN's training-inference process. Experiments on one synthetic and eight real-world graph datasets confirm consistent improvements over existing metrics in estimating the accuracy of GCN- and GAT-based architectures on the node classification task.
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The study proposes and tests a technique for automated emotion recognition through mouth detection via Convolutional Neural Networks (CNN), meant to be applied for supporting people with health disorders with communication skills issues (e.g. muscle wasting, stroke, autism, or, more simply, pain) in order to recognize emotions and generate real-time feedback, or data feeding supporting systems. The software system starts the computation identifying if a face is present on the acquired image, then it looks for the mouth location and extracts the corresponding features. Both tasks are carried out using Haar Feature-based Classifiers, which guarantee fast execution and promising performance. If our previous works focused on visual micro-expressions for personalized training on a single user, this strategy aims to train the system also on generalized faces data sets.
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To analyze this characteristic of vulnerability, we developed an automated deep learning method for detecting microvessels in intravascular optical coherence tomography (IVOCT) images. A total of 8,403 IVOCT image frames from 85 lesions and 37 normal segments were analyzed. Manual annotation was done using a dedicated software (OCTOPUS) previously developed by our group. Data augmentation in the polar (r,{\theta}) domain was applied to raw IVOCT images to ensure that microvessels appear at all possible angles. Pre-processing methods included guidewire/shadow detection, lumen segmentation, pixel shifting, and noise reduction. DeepLab v3+ was used to segment microvessel candidates. A bounding box on each candidate was classified as either microvessel or non-microvessel using a shallow convolutional neural network. For better classification, we used data augmentation (i.e., angle rotation) on bounding boxes with a microvessel during network training. Data augmentation and pre-processing steps improved microvessel segmentation performance significantly, yielding a method with Dice of 0.71+/-0.10 and pixel-wise sensitivity/specificity of 87.7+/-6.6%/99.8+/-0.1%. The network for classifying microvessels from candidates performed exceptionally well, with sensitivity of 99.5+/-0.3%, specificity of 98.8+/-1.0%, and accuracy of 99.1+/-0.5%. The classification step eliminated the majority of residual false positives, and the Dice coefficient increased from 0.71 to 0.73. In addition, our method produced 698 image frames with microvessels present, compared to 730 from manual analysis, representing a 4.4% difference. When compared to the manual method, the automated method improved microvessel continuity, implying improved segmentation performance. The method will be useful for research purposes as well as potential future treatment planning.
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随着车身可穿戴感应技术的发展,人类活动的识别已成为一个有吸引力的研究领域。借助舒适的电子质地,传感器可以嵌入衣服中,以便可以长期记录人类运动。但是,一个长期存在的问题是如何处理通过相对于身体运动引入的运动人工制品。令人惊讶的是,最近的经验发现表明,与刚性连接的传感器相比,与固定的传感器相比,布置的传感器实际上可以实现更高的活动识别精度,尤其是在从短时间窗口中预测时。在这项工作中,引入了概率模型,其中通过织物传感记录的运动之间的统计距离增加了这种提高的准确性和呼吸。模型的预测在模拟和真实的人类运动捕获实验中得到了验证,很明显,这种反直觉效应是紧密捕获的。
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对于移动机器人而言,与铰接式对象的交互是一项具有挑战性但重要的任务。为了应对这一挑战,我们提出了一条新型的闭环控制管道,该管道将负担能力估计的操纵先验与基于采样的全身控制相结合。我们介绍了完全反映了代理的能力和体现的代理意识提供的概念,我们表明它们的表现优于其最先进的对应物,这些对应物仅以最终效果的几何形状为条件。此外,发现闭环负担推论使代理可以将任务分为多个非连续运动,并从失败和意外状态中恢复。最后,管道能够执行长途移动操作任务,即在现实世界中开放和关闭烤箱,成功率很高(开放:71%,关闭:72%)。
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由于存在对抗性攻击,因此在安全至关重要系统中使用神经网络需要安全,可靠的模型。了解任何输入X的最小对抗扰动,或等效地知道X与分类边界的距离,可以评估分类鲁棒性,从而提供可认证的预测。不幸的是,计算此类距离的最新技术在计算上很昂贵,因此不适合在线应用程序。这项工作提出了一个新型的分类器家族,即签名的距离分类器(SDC),从理论的角度来看,它直接输出X与分类边界的确切距离,而不是概率分数(例如SoftMax)。 SDC代表一个强大的设计分类器家庭。为了实际解决SDC的理论要求,提出了一种名为Unitary级别神经网络的新型网络体系结构。实验结果表明,所提出的体系结构近似于签名的距离分类器,因此允许以单个推断为代价对X进行在线认证分类。
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在这项工作中,我们提出了一种神经方法,用于重建描述层次相互作用的生根树图,使用新颖的表示,我们将其称为最低的共同祖先世代(LCAG)矩阵。这种紧凑的配方等效于邻接矩阵,但是如果直接使用邻接矩阵,则可以单独从叶子中学习树的结构,而无需先前的假设。因此,采用LCAG启用了第一个端到端的可训练解决方案,该解决方案仅使用末端树叶直接学习不同树大小的层次结构。在高能量粒子物理学的情况下,粒子衰减形成了分层树结构,只能通过实验观察到最终产物,并且可能的树的大型组合空间使分析溶液变得很棘手。我们证明了LCAG用作使用变压器编码器和神经关系编码器编码器图神经网络的模拟粒子物理衰减结构的任务。采用这种方法,我们能够正确预测LCAG纯粹是从叶子特征中的LCAG,最大树深度为$ 8 $ in $ 92.5 \%\%的树木箱子,最高$ 6 $叶子(包括)和$ 59.7 \%\%\%\%的树木$在我们的模拟数据集中$ 10 $。
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为了识别动态网络中嵌入的系统(模块),必须制定一个多输入估计问题,该问题需要测量某些节点并将其作为预测输入。但是,由于传感器选择和放置问题,在许多实际情况下,其中一些节点可能无法测量。这可能会导致目标模块的偏差估计。此外,与多输入结构相关的识别问题可能需要确定实验者不特别感兴趣的大量参数,并且在大型网络中的计算复杂性增加。在本文中,我们通过使用数据增强策略来解决这些问题,该策略使我们能够重建缺失的节点测量并提高估计目标模块的准确性。为此,我们使用基于正规化的基于内核的方法和近似推理方法开发了系统识别方法。为感兴趣的模块保留一个参数模型,我们将其他模块作为高斯过程(GP)建模,并用所谓的稳定样条核给出的内核。经验贝叶斯(EB)方法用于估计目标模块的参数。相关的优化问题是使用预期最大化(EM)方法来解决的,在该方法中,我们采用马尔可夫链蒙特卡洛(MCMC)技术来重建未知的缺失节点信息和网络动力学。动态网络示例上的数值模拟说明了开发方法的电势。
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