模型选择过程通常是单一准则决策,在该决策中,我们选择了在特定集合中最大化特定度量的模型,例如验证集的性能。我们声称这非常天真,由于过度搜索现象,可以对过度拟合的模型进行糟糕的选择,从而高估了该特定集合的性能。futhermore,现实世界数据包含模型选择过程不应忽略的噪声,并且在执行模型选择时必须考虑到。此外,我们定义了四个理论最优条件,我们可以追求这些条件,以更好地选择模型并通过使用多标准决策算法(TOPSIS)来分析它们,该算法(TOPSIS)认为代理最佳条件以选择合理的模型。
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神经网络体系结构的定义是执行最关键和最具挑战性的任务之一。在本文中,我们提出了平行密码。ParallelMLPS是一种可以通过探索现代CPU和GPU的局部性和并行功能的原理来实现具有不同数量神经元和激活功能的几个独立多层感知神经网络的训练。该技术的核心思想是使用修改的矩阵乘法,该矩阵乘法将序数矩阵乘法替换为两个简单的矩阵操作,这些矩阵操作允许梯度流动的单独且独立的路径,可以在其他情况下使用。我们已经在模拟数据集中评估了我们的算法,该数据集使用10,000种不同的模型来改变样品,功能和批次的数量。如果与顺序方法相比,我们实现了从1到4个数量级的训练速度。
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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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使用机器学习算法从未标记的文本中提取知识可能很复杂。文档分类和信息检索是两个应用程序,可以从无监督的学习(例如文本聚类和主题建模)中受益,包括探索性数据分析。但是,无监督的学习范式提出了可重复性问题。初始化可能会导致可变性,具体取决于机器学习算法。此外,关于群集几何形状,扭曲可能会产生误导。在原因中,异常值和异常的存在可能是决定因素。尽管初始化和异常问题与文本群集和主题建模相关,但作者并未找到对它们的深入分析。这项调查提供了这些亚地区的系统文献综述(2011-2022),并提出了共同的术语,因为类似的程序具有不同的术语。作者描述了研究机会,趋势和开放问题。附录总结了与审查的作品直接或间接相关的文本矢量化,分解和聚类算法的理论背景。
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这项工作使用来自建设性模拟的可靠数据比较了监督的机器学习方法,以估算空袭期间发射导弹的最有效时刻。我们采用了重采样技术来改善预测模型,分析准确性,精度,召回和F1得分。的确,我们可以根据决策树以及其他算法对重采样技术的显着敏感性来确定模型的显着性能。最佳F1分数的模型的值分别为0.379和0.465,而没有重新采样技术,这一值分别增加了22.69%。因此,如果理想,重新采样技术可以改善模型的召回率和F1得分,而准确性和精确度略有下降。因此,通过通过建设性模拟获得的数据,可以根据机器学习模型开发决策支持工具,从而可以提高BVR空中战斗的飞行质量,从而提高进攻任务的有效性以达到特定目标。
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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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A Digital Twin (DT) is a simulation of a physical system that provides information to make decisions that add economic, social or commercial value. The behaviour of a physical system changes over time, a DT must therefore be continually updated with data from the physical systems to reflect its changing behaviour. For resource-constrained systems, updating a DT is non-trivial because of challenges such as on-board learning and the off-board data transfer. This paper presents a framework for updating data-driven DTs of resource-constrained systems geared towards system health monitoring. The proposed solution consists of: (1) an on-board system running a light-weight DT allowing the prioritisation and parsimonious transfer of data generated by the physical system; and (2) off-board robust updating of the DT and detection of anomalous behaviours. Two case studies are considered using a production gas turbine engine system to demonstrate the digital representation accuracy for real-world, time-varying physical systems.
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Training agents via off-policy deep reinforcement learning (RL) requires a large memory, named replay memory, that stores past experiences used for learning. These experiences are sampled, uniformly or non-uniformly, to create the batches used for training. When calculating the loss function, off-policy algorithms assume that all samples are of the same importance. In this paper, we hypothesize that training can be enhanced by assigning different importance for each experience based on their temporal-difference (TD) error directly in the training objective. We propose a novel method that introduces a weighting factor for each experience when calculating the loss function at the learning stage. In addition to improving convergence speed when used with uniform sampling, the method can be combined with prioritization methods for non-uniform sampling. Combining the proposed method with prioritization methods improves sampling efficiency while increasing the performance of TD-based off-policy RL algorithms. The effectiveness of the proposed method is demonstrated by experiments in six environments of the OpenAI Gym suite. The experimental results demonstrate that the proposed method achieves a 33%~76% reduction of convergence speed in three environments and an 11% increase in returns and a 3%~10% increase in success rate for other three environments.
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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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