由于过去几十年中获得的大量技术改进,因此可以使用机器人车进行水下勘探。这项工作描述了用于基于水下车辆的动态定位系统的开发。采用的方法是使用Lyapunov稳定性理论开发的,并通过基于神经网络的算法增强了不确定性和干扰补偿。通过数值模拟评估所提出的控制方案的性能。
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We describe a Physics-Informed Neural Network (PINN) that simulates the flow induced by the astronomical tide in a synthetic port channel, with dimensions based on the Santos - S\~ao Vicente - Bertioga Estuarine System. PINN models aim to combine the knowledge of physical systems and data-driven machine learning models. This is done by training a neural network to minimize the residuals of the governing equations in sample points. In this work, our flow is governed by the Navier-Stokes equations with some approximations. There are two main novelties in this paper. First, we design our model to assume that the flow is periodic in time, which is not feasible in conventional simulation methods. Second, we evaluate the benefit of resampling the function evaluation points during training, which has a near zero computational cost and has been verified to improve the final model, especially for small batch sizes. Finally, we discuss some limitations of the approximations used in the Navier-Stokes equations regarding the modeling of turbulence and how it interacts with PINNs.
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研究人员通常会采用数值方法来理解和预测海洋动力学,这是掌握环境现象的关键任务。在地形图很复杂,有关基础过程的知识不完整或应用程序至关重要的情况下,此类方法可能不适合。另一方面,如果观察到海洋动力学,则可以通过最近的机器学习方法来利用它们。在本文中,我们描述了一种数据驱动的方法,可以预测环境变量,例如巴西东南海岸的Santos-Sao Vicente-Bertioga estuarine系统的当前速度和海面高度。我们的模型通过连接最新的序列模型(LSTM和Transformers)以及关系模型(图神经网络)来利用时间和空间归纳偏见,以学习时间特征和空间特征,观察站点之间共享的关系。我们将结果与桑托斯运营预测系统(SOFS)进行比较。实验表明,我们的模型可以实现更好的结果,同时保持灵活性和很少的领域知识依赖性。
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Delimiting salt inclusions from migrated images is a time-consuming activity that relies on highly human-curated analysis and is subject to interpretation errors or limitations of the methods available. We propose to use migrated images produced from an inaccurate velocity model (with a reasonable approximation of sediment velocity, but without salt inclusions) to predict the correct salt inclusions shape using a Convolutional Neural Network (CNN). Our approach relies on subsurface Common Image Gathers to focus the sediments' reflections around the zero offset and to spread the energy of salt reflections over large offsets. Using synthetic data, we trained a U-Net to use common-offset subsurface images as input channels for the CNN and the correct salt-masks as network output. The network learned to predict the salt inclusions masks with high accuracy; moreover, it also performed well when applied to synthetic benchmark data sets that were not previously introduced. Our training process tuned the U-Net to successfully learn the shape of complex salt bodies from partially focused subsurface offset images.
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数字乳房X光检查仍然是乳腺癌筛选最常见的成像工具。虽然使用数字乳房X线照相术用于癌症筛查的益处超过了与X射线曝光相关的风险,但是辐射剂量必须尽可能低,同时保持所产生的图像的诊断效用,从而最大限度地减少患者风险。许多研究通过使用深神经网络恢复低剂量图像来调查剂量降低的可行性。在这些情况下,选择适当的培训数据库和丢失功能至关重要,并影响结果的质量。在这项工作中,提出了一种修改了具有分层跳过连接的Reset架构,以恢复低剂量数字乳房X光检查。我们将恢复的图像与标准的全剂量图像进行比较。此外,我们评估了此任务的几个损失函数的性能。出于培训目的,我们从回顾性临床乳腺X线摄影考试的400次图像数据集中提取了256,000个图像贴片,其中模拟了不同的剂量水平以产生低和标准剂量对。为了在真实情况下验证网络,使用物理拟人乳房乳房映射来在商业上可获得的乳房X线摄影系统中获得真实的低剂量和标准全剂量图像,然后通过我们培训的模型处理。以前呈现的低剂量数字乳房X线摄影的分析恢复模型用作这项工作中的基准。通过信噪比(SNR)进行客观评估,并且平均归一化平方误差(MNSE),分解成残余噪声和偏置。结果表明,感知损失功能(PL4)能够实现全剂量采集的几乎相同的噪声水平,同时导致与其他损耗功能相比较小的信号偏差。
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心脏听诊是用于检测和识别许多心脏病的最具成本效益的技术之一。基于Auscultation的计算机辅助决策系统可以支持他们的决定中的医生。遗憾的是,在临床试验中的应用仍然很小,因为它们中的大多数仅旨在检测音盲局部信号中的额外或异常波的存在,即,仅提供二进制地面真理变量(普通VS异常)。这主要是由于缺乏大型公共数据集,其中存在对这种异常波(例如,心脏杂音)的更详细描述。为基于听诊的医疗建议系统铺平了更有效的研究,我们的团队准备了目前最大的儿科心声数据集。从1568名患者的四个主要听诊位置收集了5282个录音,在此过程中,手动注释了215780人的心声。此外,并且首次通过专家注释器根据其定时,形状,俯仰,分级和质量来手动注释每个心脏杂音。此外,鉴定了杂音的听诊位置以及杂音更集中检测到杂音的位置位置。对于相对大量的心脏声音的这种详细描述可以为新机器学习算法铺平道路,该算法具有真实世界的应用,用于检测和分析诊断目的的杂波。
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When simulating soft robots, both their morphology and their controllers play important roles in task performance. This paper introduces a new method to co-evolve these two components in the same process. We do that by using the hyperNEAT algorithm to generate two separate neural networks in one pass, one responsible for the design of the robot body structure and the other for the control of the robot. The key difference between our method and most existing approaches is that it does not treat the development of the morphology and the controller as separate processes. Similar to nature, our method derives both the "brain" and the "body" of an agent from a single genome and develops them together. While our approach is more realistic and doesn't require an arbitrary separation of processes during evolution, it also makes the problem more complex because the search space for this single genome becomes larger and any mutation to the genome affects "brain" and the "body" at the same time. Additionally, we present a new speciation function that takes into consideration both the genotypic distance, as is the standard for NEAT, and the similarity between robot bodies. By using this function, agents with very different bodies are more likely to be in different species, this allows robots with different morphologies to have more specialized controllers since they won't crossover with other robots that are too different from them. We evaluate the presented methods on four tasks and observe that even if the search space was larger, having a single genome makes the evolution process converge faster when compared to having separated genomes for body and control. The agents in our population also show morphologies with a high degree of regularity and controllers capable of coordinating the voxels to produce the necessary movements.
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Recently, there has been an interest in improving the resources available in Intrusion Detection System (IDS) techniques. In this sense, several studies related to cybersecurity show that the environment invasions and information kidnapping are increasingly recurrent and complex. The criticality of the business involving operations in an environment using computing resources does not allow the vulnerability of the information. Cybersecurity has taken on a dimension within the universe of indispensable technology in corporations, and the prevention of risks of invasions into the environment is dealt with daily by Security teams. Thus, the main objective of the study was to investigate the Ensemble Learning technique using the Stacking method, supported by the Support Vector Machine (SVM) and k-Nearest Neighbour (kNN) algorithms aiming at an optimization of the results for DDoS attack detection. For this, the Intrusion Detection System concept was used with the application of the Data Mining and Machine Learning Orange tool to obtain better results
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Candidate axiom scoring is the task of assessing the acceptability of a candidate axiom against the evidence provided by known facts or data. The ability to score candidate axioms reliably is required for automated schema or ontology induction, but it can also be valuable for ontology and/or knowledge graph validation. Accurate axiom scoring heuristics are often computationally expensive, which is an issue if you wish to use them in iterative search techniques like level-wise generate-and-test or evolutionary algorithms, which require scoring a large number of candidate axioms. We address the problem of developing a predictive model as a substitute for reasoning that predicts the possibility score of candidate class axioms and is quick enough to be employed in such situations. We use a semantic similarity measure taken from an ontology's subsumption structure for this purpose. We show that the approach provided in this work can accurately learn the possibility scores of candidate OWL class axioms and that it can do so for a variety of OWL class axioms.
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Automatic Text Summarization (ATS) is becoming relevant with the growth of textual data; however, with the popularization of public large-scale datasets, some recent machine learning approaches have focused on dense models and architectures that, despite producing notable results, usually turn out in models difficult to interpret. Given the challenge behind interpretable learning-based text summarization and the importance it may have for evolving the current state of the ATS field, this work studies the application of two modern Generalized Additive Models with interactions, namely Explainable Boosting Machine and GAMI-Net, to the extractive summarization problem based on linguistic features and binary classification.
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