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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The Elo algorithm, due to its simplicity, is widely used for rating in sports competitions as well as in other applications where the rating/ranking is a useful tool for predicting future results. However, despite its widespread use, a detailed understanding of the convergence properties of the Elo algorithm is still lacking. Aiming to fill this gap, this paper presents a comprehensive (stochastic) analysis of the Elo algorithm, considering round-robin (one-on-one) competitions. Specifically, analytical expressions are derived characterizing the behavior/evolution of the skills and of important performance metrics. Then, taking into account the relationship between the behavior of the algorithm and the step-size value, which is a hyperparameter that can be controlled, some design guidelines as well as discussions about the performance of the algorithm are provided. To illustrate the applicability of the theoretical findings, experimental results are shown, corroborating the very good match between analytical predictions and those obtained from the algorithm using real-world data (from the Italian SuperLega, Volleyball League).
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Integrated information theory (IIT) is a theoretical framework that provides a quantitative measure to estimate when a physical system is conscious, its degree of consciousness, and the complexity of the qualia space that the system is experiencing. Formally, IIT rests on the assumption that if a surrogate physical system can fully embed the phenomenological properties of consciousness, then the system properties must be constrained by the properties of the qualia being experienced. Following this assumption, IIT represents the physical system as a network of interconnected elements that can be thought of as a probabilistic causal graph, $\mathcal{G}$, where each node has an input-output function and all the graph is encoded in a transition probability matrix. Consequently, IIT's quantitative measure of consciousness, $\Phi$, is computed with respect to the transition probability matrix and the present state of the graph. In this paper, we provide a random search algorithm that is able to optimize $\Phi$ in order to investigate, as the number of nodes increases, the structure of the graphs that have higher $\Phi$. We also provide arguments that show the difficulties of applying more complex black-box search algorithms, such as Bayesian optimization or metaheuristics, in this particular problem. Additionally, we suggest specific research lines for these techniques to enhance the search algorithm that guarantees maximal $\Phi$.
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Atrial Fibrillation (AF) is characterized by disorganised electrical activity in the atria and is known to be sustained by the presence of regions of fibrosis (scars) or functional cellular remodeling, both of which may lead to areas of slow conduction. Estimating the effective conductivity of the myocardium and identifying regions of abnormal propagation is therefore crucial for the effective treatment of AF. We hypothesise that the spatial distribution of tissue conductivity can be directly inferred from an array of concurrently acquired contact electrograms (EGMs). We generate a dataset of simulated cardiac AP propagation using randomised scar distributions and a phenomenological cardiac model and calculate contact electrograms at various positions on the field. A deep neural network, based on a modified U-net architecture, is trained to estimate the location of the scar and quantify conductivity of the tissue with a Jaccard index of $91$%. We adapt a wavelet-based surrogate testing analysis to confirm that the inferred conductivity distribution is an accurate representation of the ground truth input to the model. We find that the root mean square error (RMSE) between the ground truth and our predictions is significantly smaller ($p_{val}=0.007$) than the RMSE between the ground truth and surrogate samples.
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Large language models (LLMs) have been shown to be able to perform new tasks based on a few demonstrations or natural language instructions. While these capabilities have led to widespread adoption, most LLMs are developed by resource-rich organizations and are frequently kept from the public. As a step towards democratizing this powerful technology, we present BLOOM, a 176B-parameter open-access language model designed and built thanks to a collaboration of hundreds of researchers. BLOOM is a decoder-only Transformer language model that was trained on the ROOTS corpus, a dataset comprising hundreds of sources in 46 natural and 13 programming languages (59 in total). We find that BLOOM achieves competitive performance on a wide variety of benchmarks, with stronger results after undergoing multitask prompted finetuning. To facilitate future research and applications using LLMs, we publicly release our models and code under the Responsible AI License.
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通用近似定理断言,单个隐藏层神经网络在紧凑型集合上具有任何所需的精度,可以近似连续函数。作为存在的结果,通用近似定理支持在各种应用程序中使用神经网络,包括回归和分类任务。通用近似定理不仅限于实现的神经网络,而且还具有复杂,季节,Tessarines和Clifford值的神经网络。本文扩展了广泛的超复杂性神经网络的通用近似定理。确切地说,我们首先介绍非分类超复杂代数的概念。复数,偶数和苔丝是非分类超复合代数的示例。然后,我们陈述了在非分类代数上定义的超复合值的神经网络的通用近似定理。
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公共数据集在推进车牌识别(LPR)的最新技术方面发挥了关键作用。尽管数据集偏见在计算机视觉社区中被认为是一个严重的问题,但在LPR文献中很大程度上忽略了它。 LPR模型通常在每个数据集上进行训练和评估。在这种情况下,他们经常在接受培训的数据集中证明了强大的证明,但在看不见的数据集中表现出有限的性能。因此,这项工作研究了LPR上下文中的数据集偏差问题。我们在八个数据集上进行了实验,在巴西收集了四个,在中国大陆进行了实验,并观察到每个数据集都有一个独特的,可识别的“签名”,因为轻量级分类模型预测了车牌(LP)图像的源数据集,其图像的源95%的精度。在我们的讨论中,我们提请人们注意以下事实:大多数LPR模型可能正在利用此类签名,以以失去概括能力为代价,以改善每个数据集中的结果。这些结果强调了评估跨数据库设置中LPR模型的重要性,因为它们提供了比数据库内部的更好的概括(因此实际性能)。
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在计算和数据方面,大型语言模型的预培训通常需要大量资源。经常使用的Web源(例如Common Crawl)可能包含足够的噪声,以使这种预训练的亚地区。在这项工作中,我们尝试了西班牙语版本的MC4的不同采样方法,并提出了一种新颖的以数据为中心的技术,我们将其命名为$ \ textit {Perplexity sampling} $,该技术可实现大约一半的语言模型的预培训步骤并使用五分之一的数据。最终的模型与当前的最新机构相当,甚至可以为某些任务获得更好的结果。我们的工作证明了变形金刚的多功能性,并为小型团队以有限的预算培训模型铺平了道路。我们的型号可在此$ \ href {https://huggingface.co/bertin-project} {url} $中获得。
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功能工程已成为提高模型预测性能并生产优质数据集的最重要步骤之一。但是,此过程需要非平凡的域知识,涉及耗时的过程。因此,自动化此过程已成为研究的积极领域,并在工业应用中感兴趣。在本文中,提出了一种称为基于元学习和因果关系的特征工程(MACFE)的新方法。我们的方法基于使用元学习,特征分布编码和因果关系特征选择。在MacFe中,使用元学习来找到最佳的转换,然后通过预选为“原始”功能来加速搜索,鉴于其因果关系的相关性。对流行分类数据集的实验评估表明,MACFE可以改善八个分类器的预测性能,表现平均最低的最新方法至少提高6.54%,并且比最佳先前工作的提高了2.71%。
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