在本文中,我们对数值模拟的加速感兴趣。我们专注于高超音速行星再入问题,该问题涉及耦合流体动力学和化学反应。模拟化学反应需要大部分计算时间,但另一方面,无法避免获得准确的预测。我们面临成本效率和准确性之间的权衡:模拟代码必须足够有效地在操作环境中使用,但必须足够准确,以忠实地预测现象。为了解决这个权衡,我们设计了一个混合模拟代码,将传统的流体动态求解器与近似化学反应的神经网络耦合。当在大数据上下文中应用以及它们源于其矩阵矢量结构的效率时,我们依靠它们的力量来实现重要的加速因子($ \ tims 10 $至$ \ times 18.6 $)。本文旨在解释我们如何在实践中设计这种具有成本效益的混合模拟代码。最重要的是,我们描述了确保准确性保证的方法论,使我们能够超越传统的替代建模,并将这些代码用作参考。
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通过神经网络解决新的机器学习问题总是意味着优化众多的超参数,以定义其结构并强烈影响其性能。在这项工作中,我们研究了基于希尔伯特·史克米特独立标准(HSIC)的面向目标灵敏度分析的使用,用于超参数分析和优化。超参数生活在通常复杂而尴尬的空间中。它们可以具有不同的本质(分类,离散,布尔,连续),相互作用并具有相互依存关系。所有这些使得执行经典灵敏度分析是不平凡的。我们可以减轻这些困难,以获取能够量化超参数对神经网络的最终错误的相对影响的强大分析指数。这种有价值的工具使我们能够更好地理解超参数,并使超参数优化更容易解释。我们在超参数优化的背景下说明了这些知识的好处,并得出了一种基于HSIC的优化算法,我们将其应用于MNIST和CIFAR,经典的机器学习数据集,但也适用于Runge功能和Bateman方程解决方案,兴趣解决方案的近似值,用于科学的机器学习。该方法产生既有竞争力又具有成本效益的神经网络。
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Many datasets are biased, namely they contain easy-to-learn features that are highly correlated with the target class only in the dataset but not in the true underlying distribution of the data. For this reason, learning unbiased models from biased data has become a very relevant research topic in the last years. In this work, we tackle the problem of learning representations that are robust to biases. We first present a margin-based theoretical framework that allows us to clarify why recent contrastive losses (InfoNCE, SupCon, etc.) can fail when dealing with biased data. Based on that, we derive a novel formulation of the supervised contrastive loss (epsilon-SupInfoNCE), providing more accurate control of the minimal distance between positive and negative samples. Furthermore, thanks to our theoretical framework, we also propose FairKL, a new debiasing regularization loss, that works well even with extremely biased data. We validate the proposed losses on standard vision datasets including CIFAR10, CIFAR100, and ImageNet, and we assess the debiasing capability of FairKL with epsilon-SupInfoNCE, reaching state-of-the-art performance on a number of biased datasets, including real instances of biases in the wild.
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弱监督的对象本地化(WSOL)旨在学习仅使用图像级类别标签编码对象位置的表示形式。但是,许多物体可以在不同水平的粒度标记。它是动物,鸟还是大角的猫头鹰?我们应该使用哪些图像级标签?在本文中,我们研究了标签粒度在WSOL中的作用。为了促进这项调查,我们引入了Inatloc500,这是一个新的用于WSOL的大规模细粒基准数据集。令人惊讶的是,我们发现选择正确的训练标签粒度比选择最佳的WSOL算法提供了更大的性能。我们还表明,更改标签粒度可以显着提高数据效率。
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在神经网络对功能的监督学习的背景下,我们声称并经验证明,当数据集的分布集中在学习功能陡峭的区域时,神经网络会产生更好的结果。我们首先使用泰勒(Taylor)扩展以数学上可行的方式来欺骗这一假设,并根据要学习的功能的导数强调新的培训分布。然后,理论推导允许构建一种我们称为基于方差的样本加权(VBSW)的方法。VBSW使用标签局部差异来加权训练点。该方法是一般,可扩展的,具有成本效益的,并且可以显着提高大量神经网络的性能,以在图像,文本和多元数据上进行各种分类和回归任务。我们通过涉及从线性模型到重新NET和BERT的神经网络的实验来强调其优势。
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Computational units in artificial neural networks follow a simplified model of biological neurons. In the biological model, the output signal of a neuron runs down the axon, splits following the many branches at its end, and passes identically to all the downward neurons of the network. Each of the downward neurons will use their copy of this signal as one of many inputs dendrites, integrate them all and fire an output, if above some threshold. In the artificial neural network, this translates to the fact that the nonlinear filtering of the signal is performed in the upward neuron, meaning that in practice the same activation is shared between all the downward neurons that use that signal as their input. Dendrites thus play a passive role. We propose a slightly more complex model for the biological neuron, where dendrites play an active role: the activation in the output of the upward neuron becomes optional, and instead the signals going through each dendrite undergo independent nonlinear filterings, before the linear combination. We implement this new model into a ReLU computational unit and discuss its biological plausibility. We compare this new computational unit with the standard one and describe it from a geometrical point of view. We provide a Keras implementation of this unit into fully connected and convolutional layers and estimate their FLOPs and weights change. We then use these layers in ResNet architectures on CIFAR-10, CIFAR-100, Imagenette, and Imagewoof, obtaining performance improvements over standard ResNets up to 1.73%. Finally, we prove a universal representation theorem for continuous functions on compact sets and show that this new unit has more representational power than its standard counterpart.
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Real-world robotic grasping can be done robustly if a complete 3D Point Cloud Data (PCD) of an object is available. However, in practice, PCDs are often incomplete when objects are viewed from few and sparse viewpoints before the grasping action, leading to the generation of wrong or inaccurate grasp poses. We propose a novel grasping strategy, named 3DSGrasp, that predicts the missing geometry from the partial PCD to produce reliable grasp poses. Our proposed PCD completion network is a Transformer-based encoder-decoder network with an Offset-Attention layer. Our network is inherently invariant to the object pose and point's permutation, which generates PCDs that are geometrically consistent and completed properly. Experiments on a wide range of partial PCD show that 3DSGrasp outperforms the best state-of-the-art method on PCD completion tasks and largely improves the grasping success rate in real-world scenarios. The code and dataset will be made available upon acceptance.
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The open-radio access network (O-RAN) embraces cloudification and network function virtualization for base-band function processing by dis-aggregated radio units (RUs), distributed units (DUs), and centralized units (CUs). These enable the cloud-RAN vision in full, where multiple mobile network operators (MNOs) can install their proprietary or open RUs, but lease on-demand computational resources for DU-CU functions from commonly available open-clouds via open x-haul interfaces. In this paper, we propose and compare the performances of min-max fairness and Vickrey-Clarke-Groves (VCG) auction-based x-haul and DU-CU resource allocation mechanisms to create a multi-tenant O-RAN ecosystem that is sustainable for small, medium, and large MNOs. The min-max fair approach minimizes the maximum OPEX of RUs through cost-sharing proportional to their demands, whereas the VCG auction-based approach minimizes the total OPEX for all resources utilized while extracting truthful demands from RUs. We consider time-wavelength division multiplexed (TWDM) passive optical network (PON)-based x-haul interfaces where PON virtualization technique is used to flexibly provide optical connections among RUs and edge-clouds at macro-cell RU locations as well as open-clouds at the central office locations. Moreover, we design efficient heuristics that yield significantly better economic efficiency and network resource utilization than conventional greedy resource allocation algorithms and reinforcement learning-based algorithms.
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When testing conditions differ from those represented in training data, so-called out-of-distribution (OOD) inputs can mar the reliability of black-box learned components in the modern robot autonomy stack. Therefore, coping with OOD data is an important challenge on the path towards trustworthy learning-enabled open-world autonomy. In this paper, we aim to demystify the topic of OOD data and its associated challenges in the context of data-driven robotic systems, drawing connections to emerging paradigms in the ML community that study the effect of OOD data on learned models in isolation. We argue that as roboticists, we should reason about the overall system-level competence of a robot as it performs tasks in OOD conditions. We highlight key research questions around this system-level view of OOD problems to guide future research toward safe and reliable learning-enabled autonomy.
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Artificial neural networks can learn complex, salient data features to achieve a given task. On the opposite end of the spectrum, mathematically grounded methods such as topological data analysis allow users to design analysis pipelines fully aware of data constraints and symmetries. We introduce a class of persistence-based neural network layers. Persistence-based layers allow the users to easily inject knowledge about symmetries (equivariance) respected by the data, are equipped with learnable weights, and can be composed with state-of-the-art neural architectures.
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