A systematic review on machine-learning strategies for improving generalizability (cross-subjects and cross-sessions) electroencephalography (EEG) based in emotion classification was realized. In this context, the non-stationarity of EEG signals is a critical issue and can lead to the Dataset Shift problem. Several architectures and methods have been proposed to address this issue, mainly based on transfer learning methods. 418 papers were retrieved from the Scopus, IEEE Xplore and PubMed databases through a search query focusing on modern machine learning techniques for generalization in EEG-based emotion assessment. Among these papers, 75 were found eligible based on their relevance to the problem. Studies lacking a specific cross-subject and cross-session validation strategy and making use of other biosignals as support were excluded. On the basis of the selected papers' analysis, a taxonomy of the studies employing Machine Learning (ML) methods was proposed, together with a brief discussion on the different ML approaches involved. The studies with the best results in terms of average classification accuracy were identified, supporting that transfer learning methods seem to perform better than other approaches. A discussion is proposed on the impact of (i) the emotion theoretical models and (ii) psychological screening of the experimental sample on the classifier performances.
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We combine the metrics of distance and isolation to develop the \textit{Analytic Isolation and Distance-based Anomaly (AIDA) detection algorithm}. AIDA is the first distance-based method that does not rely on the concept of nearest-neighbours, making it a parameter-free model. Differently from the prevailing literature, in which the isolation metric is always computed via simulations, we show that AIDA admits an analytical expression for the outlier score, providing new insights into the isolation metric. Additionally, we present an anomaly explanation method based on AIDA, the \textit{Tempered Isolation-based eXplanation (TIX)} algorithm, which finds the most relevant outlier features even in data sets with hundreds of dimensions. We test both algorithms on synthetic and empirical data: we show that AIDA is competitive when compared to other state-of-the-art methods, and it is superior in finding outliers hidden in multidimensional feature subspaces. Finally, we illustrate how the TIX algorithm is able to find outliers in multidimensional feature subspaces, and use these explanations to analyze common benchmarks used in anomaly detection.
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Crypto-coins (also known as cryptocurrencies) are tradable digital assets. Notable examples include Bitcoin, Ether and Litecoin. Ownerships of cryptocoins are registered on distributed ledgers (i.e., blockchains). Secure encryption techniques guarantee the security of the transactions (transfers of coins across owners), registered into the ledger. Cryptocoins are exchanged for specific trading prices. While history has shown the extreme volatility of such trading prices across all different sets of crypto-assets, it remains unclear what and if there are tight relations between the trading prices of different cryptocoins. Major coin exchanges (i.e., Coinbase) provide trend correlation indicators to coin owners, suggesting possible acquisitions or sells. However, these correlations remain largely unvalidated. In this paper, we shed lights on the trend correlations across a large variety of cryptocoins, by investigating their coin-price correlation trends over a period of two years. Our experimental results suggest strong correlation patterns between main coins (Ethereum, Bitcoin) and alt-coins. We believe our study can support forecasting techniques for time-series modeling in the context of crypto-coins. We release our dataset and code to reproduce our analysis to the research community.
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深度学习体系结构中离散算法组件的集成具有许多应用。最近,隐含的最大似然估计(Imle,Niepert,Minervini和Franceschi 2021)是一类用于离散指数家庭分布的梯度估计器,是通过通过与路径级别梯度估计器组合隐式分化来结合隐式分化的。但是,由于梯度的有限差近似,它对需要由用户指定的有限差步长的选择特别敏感。在这项工作中,我们提出了自适应IMLE(AIMLE),是第一个用于复杂离散分布的自适应梯度估计器:它通过在梯度估计中以偏见程度来换取梯度信息的密度来适应IMLE的目标分布。我们从经验上评估了关于合成示例的估计量,以及学习解释,离散的变异自动编码器和神经关系推理任务。在我们的实验中,我们表明我们的自适应梯度估计器可以产生忠实的估计值,同时需要的样本较少,而样品比其他梯度估计器少。
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眼科图像和衍生物,例如视网膜神经纤维层(RNFL)厚度图对于检测和监测眼科疾病至关重要(例如,青光眼)。对于计算机辅助诊断眼疾病,关键技术是自动从眼科图像中提取有意义的特征,这些特征可以揭示与功能视觉丧失相关的生物标志物(例如RNFL变薄模式)。然而,将结构性视网膜损伤与人类视力丧失联系起来的眼科图像的表示,主要是由于患者之间的解剖学变化很大。在存在图像伪像的情况下,这项任务变得更加具有挑战性,由于图像采集和自动细分,这很常见。在本文中,我们提出了一个耐伪造的无监督的学习框架,该框架称为眼科图像的学习表示。 Eyelearn具有一个伪影校正模块,可以学习可以最好地预测无伪影眼镜图像的表示形式。此外,Eyelearn采用聚类引导的对比度学习策略,以明确捕获内部和间形的亲和力。在训练过程中,图像在簇中动态组织,以形成对比样品,其中鼓励在相同或不同的簇中分别学习相似或不同的表示形式。为了评估包冰者,我们使用青光眼患者的现实世界眼科摄影图数据集使用学习的表示形式进行视野预测和青光眼检测。广泛的实验和与最先进方法的比较验证了眼球从眼科图像中学习最佳特征表示的有效性。
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基于分解的模型(FMS),例如Distmult,在知识图完成(KGC)任务中享有持久的成功,通常优于图形神经网络(GNNS)。但是,与GNN不同,FMS难以合并节点特征并概括在归纳环境中看不见的节点。我们的工作通过提出重构GNN来弥合FMS和GNN之间的差距。这种新的体系结构借鉴了两种建模范式,以前在很大程度上被认为是不结合的。具体地说,使用消息通讯的形式主义,我们通过将梯度下降程序重新定义为消息传播操作来展示如何将FMS施加为GNN,这构成了我们重构GNN的基础。在众多成熟的KGC基准测试中,我们的重构GNN可以实现与FMS相当的转导性能以及最先进的归纳性能,同时使用较少的参数阶数。
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沿规定的任务空间路径的冗余机器人的轨迹的离线最佳规划通常分为两个连续的过程:首先,任务空间路径倒置以获得一个联合空间路径,然后,后者通过时间定律进行参数化。如果两个过程分开,它们将无法优化相同的目标函数,最终提供了次优的结果。在本文中,提出了一种统一的方法,而动态编程是基础优化技术。它的灵活性允许安装任意约束和客观功能,从而为真实系统的最佳计划提供了一个通用框架。为了证明其适用于现实世界情景,该框架是实例化的,以进行时间优势。与数值求解器相比,所提出的方法提供了基础分辨率过程的可见性,从而超出了最佳轨迹的计算以外的进一步分析。该框架的有效性已在真正的7度自由串行链上证明。还讨论和解决了与实际控制器上执行最佳轨迹相关的问题。实验表明,所提出的框架能够有效利用运动学冗余,以优化计划级别定义的性能索引,并生成可行的轨迹,这些轨迹可以在真实硬件上执行,并具有令人满意的结果。
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可以使用几种技术来解决沿规定路径的最佳运动计划,但是大多数技术没有考虑到与环境接触时最终效用器所施加的扳手。当无法获得环境的动态模型时,就不存在合并方法来考虑相互作用的效果。无论要优化的特定性能指数如何,本文都提出了一种策略,将外部扳手包括在最佳计划算法中,考虑到任务规格。此过程是针对最小时间轨迹实例化的,并在接纳控制下执行交互任务的真实机器人进行了验证。结果证明,最终效应器扳手的包含会影响计划的轨迹,实际上改变了操纵器的动态能力。
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航天器微型振动的隔离对于成功依靠高精度指向的工具部署至关重要。 Hexapod平台代表了一个有前途的解决方案,但是与在可接受的质量和复杂性预算中获得理想的3D动态相关的困难导致了最小的实际采用。本文介绍了支柱边界条件(BCS)对系统级机械干扰抑制的影响。传统的全旋转关节构型的固有局限性被突出显示,并显示为链接质量和旋转惯性。提出并在分析上提出了针刺的BC替代方案,以减轻2D和3D的缓解。新BC的优势在任意平行操纵器中具有,并通过数值测试证明了几种六角形的几何形状。提出了具有良好性能的配置。最后,描述并验证了允许物理实现的新型平面关节。因此,这项工作可以开发不需要主动控制的微型启动平台。
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机器人的视觉系统根据应用程序的要求不同:它可能需要高精度或可靠性,受到有限的资源的约束或需要快速适应动态变化的环境。在这项工作中,我们专注于实例分割任务,并对不同的技术进行了全面的研究,这些技术允许在存在新对象或不同域的存在下调整对象分割模型。我们为针对数据流入的机器人应用设计的快速实例细分学习提供了一条管道。它基于在预训练的CNN上利用的混合方法,用于特征提取和基于快速培训的基于内核的分类器。我们还提出了一种培训协议,该协议可以通过在数据采集期间执行特征提取来缩短培训时间。我们在两个机器人数据集上基准了提议的管道,然后将其部署在一个真实的机器人上,即iCub类人体。为了这个目的,我们将方法调整为一个增量设置,在该设置中,机器人在线学习新颖对象。复制实验的代码在GitHub上公开可用。
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