分类是数据挖掘和机器学习领域中研究最多的任务之一,并且已经提出了文献中的许多作品来解决分类问题,以解决多个知识领域,例如医学,生物学,安全性和遥感。由于没有单个分类器可以为各种应用程序取得最佳结果,因此,一个很好的选择是采用分类器融合策略。分类器融合方法成功的关键点是属于合奏的分类器之间多样性和准确性的结合。借助文献中可用的大量分类模型,一个挑战是选择最终分类系统的最合适的分类器,从而产生了分类器选择策略的需求。我们通过基于一个称为CIF-E(分类器,初始化,健身函数和进化算法)的四步协议的分类器选择和融合的框架来解决这一点。我们按照提出的CIF-E协议实施和评估24种各种集合方法,并能够找到最准确的方法。在文献中最佳方法和许多其他基线中,还进行了比较分析。该实验表明,基于单变量分布算法(UMDA)的拟议进化方法可以超越许多著名的UCI数据集中最新的文献方法。
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Dataset scaling, also known as normalization, is an essential preprocessing step in a machine learning pipeline. It is aimed at adjusting attributes scales in a way that they all vary within the same range. This transformation is known to improve the performance of classification models, but there are several scaling techniques to choose from, and this choice is not generally done carefully. In this paper, we execute a broad experiment comparing the impact of 5 scaling techniques on the performances of 20 classification algorithms among monolithic and ensemble models, applying them to 82 publicly available datasets with varying imbalance ratios. Results show that the choice of scaling technique matters for classification performance, and the performance difference between the best and the worst scaling technique is relevant and statistically significant in most cases. They also indicate that choosing an inadequate technique can be more detrimental to classification performance than not scaling the data at all. We also show how the performance variation of an ensemble model, considering different scaling techniques, tends to be dictated by that of its base model. Finally, we discuss the relationship between a model's sensitivity to the choice of scaling technique and its performance and provide insights into its applicability on different model deployment scenarios. Full results and source code for the experiments in this paper are available in a GitHub repository.\footnote{https://github.com/amorimlb/scaling\_matters}
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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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Decades of progress in simulation-based surrogate-assisted optimization and unprecedented growth in computational power have enabled researchers and practitioners to optimize previously intractable complex engineering problems. This paper investigates the possible benefit of a concurrent utilization of multiple simulation-based surrogate models to solve complex discrete optimization problems. To fulfill this, the so-called Self-Adaptive Multi-surrogate Assisted Efficient Global Optimization algorithm (SAMA-DiEGO), which features a two-stage online model management strategy, is proposed and further benchmarked on fifteen binary-encoded combinatorial and fifteen ordinal problems against several state-of-the-art non-surrogate or single surrogate assisted optimization algorithms. Our findings indicate that SAMA-DiEGO can rapidly converge to better solutions on a majority of the test problems, which shows the feasibility and advantage of using multiple surrogate models in optimizing discrete problems.
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Automatic Target Recognition (ATR) is a category of computer vision algorithms which attempts to recognize targets on data obtained from different sensors. ATR algorithms are extensively used in real-world scenarios such as military and surveillance applications. Existing ATR algorithms are developed for traditional closed-set methods where training and testing have the same class distribution. Thus, these algorithms have not been robust to unknown classes not seen during the training phase, limiting their utility in real-world applications. To this end, we propose an Open-set Automatic Target Recognition framework where we enable open-set recognition capability for ATR algorithms. In addition, we introduce a plugin Category-aware Binary Classifier (CBC) module to effectively tackle unknown classes seen during inference. The proposed CBC module can be easily integrated with any existing ATR algorithms and can be trained in an end-to-end manner. Experimental results show that the proposed approach outperforms many open-set methods on the DSIAC and CIFAR-10 datasets. To the best of our knowledge, this is the first work to address the open-set classification problem for ATR algorithms. Source code is available at: https://github.com/bardisafa/Open-set-ATR.
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近年来,出于计算机视觉目的,将图像传输到远程服务器的传输急剧增加。在许多应用程序(例如监视)中,图像主要是用于自动分析的,并且很少被人类看到。在这种情况下,使用传统的压缩在比特率方面效率低下,这可能是由于关注基于人类的失真指标。因此,重要的是创建特定的图像编码方法,以供人类和机器联合使用。创建这种编解码器的机器侧的一种方法是在深神经网络中执行某些中间层执行机器任务的功能匹配。在这项工作中,我们探讨了用于培训人类和机器可学习的编解码器时所使用的层选择的效果。我们证明,使用数据处理不平等,从速率延伸的意义上讲,更深层的匹配特征是可取的。接下来,我们通过重新培训现有的可扩展人机编码模型来从经验上确认我们的发现。在我们的实验中,我们显示了这种可扩展模型的人类和机器方面的权衡,并讨论了在这方面使用更深层进行训练的好处。
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科学机器学习(SCIML)是对几个不同应用领域的兴趣越来越多的领域。在优化上下文中,基于SCIML的工具使得能够开发更有效的优化方法。但是,必须谨慎评估和执行实施优化的SCIML工具。这项工作提出了稳健性测试的推论,该测试通过表明其结果尊重通用近似值定理,从而确保了基于多物理的基于SCIML的优化的鲁棒性。该测试应用于一种新方法的框架,该方法在一系列基准测试中进行了评估,以说明其一致性。此外,将提出的方法论结果与可行优化的可行区域进行了比较,这需要更高的计算工作。因此,这项工作为保证在多目标优化中应用SCIML工具的稳健性测试提供了比存在的替代方案要低的计算努力。
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ICECUBE是一种用于检测1 GEV和1 PEV之间大气和天体中微子的光学传感器的立方公斤阵列,该阵列已部署1.45 km至2.45 km的南极的冰盖表面以下1.45 km至2.45 km。来自ICE探测器的事件的分类和重建在ICeCube数据分析中起着核心作用。重建和分类事件是一个挑战,这是由于探测器的几何形状,不均匀的散射和冰中光的吸收,并且低于100 GEV的光,每个事件产生的信号光子数量相对较少。为了应对这一挑战,可以将ICECUBE事件表示为点云图形,并将图形神经网络(GNN)作为分类和重建方法。 GNN能够将中微子事件与宇宙射线背景区分开,对不同的中微子事件类型进行分类,并重建沉积的能量,方向和相互作用顶点。基于仿真,我们提供了1-100 GEV能量范围的比较与当前ICECUBE分析中使用的当前最新最大似然技术,包括已知系统不确定性的影响。对于中微子事件分类,与当前的IceCube方法相比,GNN以固定的假阳性速率(FPR)提高了信号效率的18%。另外,GNN在固定信号效率下将FPR的降低超过8(低于半百分比)。对于能源,方向和相互作用顶点的重建,与当前最大似然技术相比,分辨率平均提高了13%-20%。当在GPU上运行时,GNN能够以几乎是2.7 kHz的中位数ICECUBE触发速率的速率处理ICECUBE事件,这打开了在在线搜索瞬态事件中使用低能量中微子的可能性。
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视频识别是由端到端学习范式主导的 - 首先初始化具有预审预周化图像模型的视频识别模型,然后对视频进行端到端培训。这使视频网络能够受益于验证的图像模型。但是,这需要大量的计算和内存资源,以便在视频上进行填充以及直接使用预审计的图像功能的替代方案,而无需填充图像骨架会导致结果不足。幸运的是,在对比视力语言预训练(剪辑)方面的最新进展为视觉识别任务的新途径铺平了道路。这些模型在大型开放式图像文本对数据上进行了预测,以丰富的语义学习强大的视觉表示。在本文中,我们介绍了有效的视频学习(EVL) - 一种有效的框架,用于直接训练具有冷冻剪辑功能的高质量视频识别模型。具体来说,我们采用轻型变压器解码器并学习查询令牌,从剪辑图像编码器中动态收集帧级空间特征。此外,我们在每个解码器层中采用局部时间模块,以发现相邻帧及其注意力图的时间线索。我们表明,尽管有效地使用冷冻的骨干训练,但我们的模型在各种视频识别数据集上学习了高质量的视频表示。代码可在https://github.com/opengvlab/feld-video-rencognition上找到。
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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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