我们通过应用更为理论证明的操作员来寻求改善神经网络中的汇集操作。我们证明Logsumexp提供了用于登录的自然或操作员。当一个人对池中汇集运算符中的元素数正确时,这将成为$ \ text {logavgexp}:= \ log(\ text {mean}(\ exp(x)))$。通过引入单个温度参数,LogavgeXP将其操作数的最大值平滑地过渡到平均值(在限制性情况下发现$ 0 ^ + $和$ t \ to + \ idty $)。在各种深度神经网络架构中,我们在实验测试的LogavgeXP,无论是没有学习的温度参数,都在电脑视觉中的各种深度神经网络架构中。
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The choice of activation functions and their motivation is a long-standing issue within the neural network community. Neuronal representations within artificial neural networks are commonly understood as logits, representing the log-odds score of presence of features within the stimulus. We derive logit-space operators equivalent to probabilistic Boolean logic-gates AND, OR, and XNOR for independent probabilities. Such theories are important to formalize more complex dendritic operations in real neurons, and these operations can be used as activation functions within a neural network, introducing probabilistic Boolean-logic as the core operation of the neural network. Since these functions involve taking multiple exponents and logarithms, they are computationally expensive and not well suited to be directly used within neural networks. Consequently, we construct efficient approximations named $\text{AND}_\text{AIL}$ (the AND operator Approximate for Independent Logits), $\text{OR}_\text{AIL}$, and $\text{XNOR}_\text{AIL}$, which utilize only comparison and addition operations, have well-behaved gradients, and can be deployed as activation functions in neural networks. Like MaxOut, $\text{AND}_\text{AIL}$ and $\text{OR}_\text{AIL}$ are generalizations of ReLU to two-dimensions. While our primary aim is to formalize dendritic computations within a logit-space probabilistic-Boolean framework, we deploy these new activation functions, both in isolation and in conjunction to demonstrate their effectiveness on a variety of tasks including image classification, transfer learning, abstract reasoning, and compositional zero-shot learning.
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Most modern convolutional neural networks (CNNs) used for object recognition are built using the same principles: Alternating convolution and max-pooling layers followed by a small number of fully connected layers. We re-evaluate the state of the art for object recognition from small images with convolutional networks, questioning the necessity of different components in the pipeline. We find that max-pooling can simply be replaced by a convolutional layer with increased stride without loss in accuracy on several image recognition benchmarks. Following this finding -and building on other recent work for finding simple network structures -we propose a new architecture that consists solely of convolutional layers and yields competitive or state of the art performance on several object recognition datasets (CIFAR-10, CIFAR-100, ImageNet). To analyze the network we introduce a new variant of the "deconvolution approach" for visualizing features learned by CNNs, which can be applied to a broader range of network structures than existing approaches.
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在本文中,我们提出了解决稳定性和卷积神经网络(CNN)的稳定性和视野的问题的神经网络。作为提高网络深度或宽度以提高性能的替代方案,我们提出了与全球加权拉普拉斯,分数拉普拉斯和逆分数拉普拉斯算子有关的基于积分的空间非识别算子,其在物理科学中的几个问题中出现。这种网络的前向传播由部分积分微分方程(PIDE)启发。我们在自动驾驶中测试基准图像分类数据集和语义分段任务的提出神经架构的有效性。此外,我们调查了这些密集的运营商的额外计算成本以及提出神经网络的前向传播的稳定性。
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Deep neural nets with a large number of parameters are very powerful machine learning systems. However, overfitting is a serious problem in such networks. Large networks are also slow to use, making it difficult to deal with overfitting by combining the predictions of many different large neural nets at test time. Dropout is a technique for addressing this problem. The key idea is to randomly drop units (along with their connections) from the neural network during training. This prevents units from co-adapting too much. During training, dropout samples from an exponential number of different "thinned" networks. At test time, it is easy to approximate the effect of averaging the predictions of all these thinned networks by simply using a single unthinned network that has smaller weights. This significantly reduces overfitting and gives major improvements over other regularization methods. We show that dropout improves the performance of neural networks on supervised learning tasks in vision, speech recognition, document classification and computational biology, obtaining state-of-the-art results on many benchmark data sets.
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我们介绍Softmax梯度篡改,一种用于修改神经网络后向通过的梯度的技术,以提高其准确性。我们的方法使用基于功率的概率变换来改变预测的概率值,然后将梯度重新计算在后向通过。这种修改导致更平滑的渐变简介,我们在经验和理论上展示。我们对剩余网络进行了转换参数进行了网格搜索。我们证明修改CUMMNET中的软MAX梯度可能导致培训准确性提高,从而增加训练数据的适合,并最大限度地利用神经网络的学习能力。当与标签平滑等正则化技术相结合时,我们获得更好的测试度量和更低的泛化间隙。 Softmax渐变篡改在ImageNet DataSet上的基线上以0.52 \%$ 0.52 \%$ 0.52 \%$ 0.52 \%。我们的方法非常通用,可以跨各种不同的网络架构和数据集使用。
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Neural networks require careful weight initialization to prevent signals from exploding or vanishing. Existing initialization schemes solve this problem in specific cases by assuming that the network has a certain activation function or topology. It is difficult to derive such weight initialization strategies, and modern architectures therefore often use these same initialization schemes even though their assumptions do not hold. This paper introduces AutoInit, a weight initialization algorithm that automatically adapts to different neural network architectures. By analytically tracking the mean and variance of signals as they propagate through the network, AutoInit appropriately scales the weights at each layer to avoid exploding or vanishing signals. Experiments demonstrate that AutoInit improves performance of convolutional, residual, and transformer networks across a range of activation function, dropout, weight decay, learning rate, and normalizer settings, and does so more reliably than data-dependent initialization methods. This flexibility allows AutoInit to initialize models for everything from small tabular tasks to large datasets such as ImageNet. Such generality turns out particularly useful in neural architecture search and in activation function discovery. In these settings, AutoInit initializes each candidate appropriately, making performance evaluations more accurate. AutoInit thus serves as an automatic configuration tool that makes design of new neural network architectures more robust. The AutoInit package provides a wrapper around TensorFlow models and is available at https://github.com/cognizant-ai-labs/autoinit.
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While machine learning is traditionally a resource intensive task, embedded systems, autonomous navigation, and the vision of the Internet of Things fuel the interest in resource-efficient approaches. These approaches aim for a carefully chosen trade-off between performance and resource consumption in terms of computation and energy. The development of such approaches is among the major challenges in current machine learning research and key to ensure a smooth transition of machine learning technology from a scientific environment with virtually unlimited computing resources into everyday's applications. In this article, we provide an overview of the current state of the art of machine learning techniques facilitating these real-world requirements. In particular, we focus on deep neural networks (DNNs), the predominant machine learning models of the past decade. We give a comprehensive overview of the vast literature that can be mainly split into three non-mutually exclusive categories: (i) quantized neural networks, (ii) network pruning, and (iii) structural efficiency. These techniques can be applied during training or as post-processing, and they are widely used to reduce the computational demands in terms of memory footprint, inference speed, and energy efficiency. We also briefly discuss different concepts of embedded hardware for DNNs and their compatibility with machine learning techniques as well as potential for energy and latency reduction. We substantiate our discussion with experiments on well-known benchmark datasets using compression techniques (quantization, pruning) for a set of resource-constrained embedded systems, such as CPUs, GPUs and FPGAs. The obtained results highlight the difficulty of finding good trade-offs between resource efficiency and predictive performance.
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Time Series Classification (TSC) is an important and challenging problem in data mining. With the increase of time series data availability, hundreds of TSC algorithms have been proposed. Among these methods, only a few have considered Deep Neural Networks (DNNs) to perform this task. This is surprising as deep learning has seen very successful applications in the last years. DNNs have indeed revolutionized the field of computer vision especially with the advent of novel deeper architectures such as Residual and Convolutional Neural Networks. Apart from images, sequential data such as text and audio can also be processed with DNNs to reach state-of-the-art performance for document classification and speech recognition. In this article, we study the current state-ofthe-art performance of deep learning algorithms for TSC by presenting an empirical study of the most recent DNN architectures for TSC. We give an overview of the most successful deep learning applications in various time series domains under a unified taxonomy of DNNs for TSC. We also provide an open source deep learning framework to the TSC community where we implemented each of the compared approaches and evaluated them on a univariate TSC benchmark (the UCR/UEA archive) and 12 multivariate time series datasets. By training 8,730 deep learning models on 97 time series datasets, we propose the most exhaustive study of DNNs for TSC to date.
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深度学习使用由其重量进行参数化的神经网络。通常通过调谐重量来直接最小化给定损耗功能来训练神经网络。在本文中,我们建议将权重重新参数转化为网络中各个节点的触发强度的目标。给定一组目标,可以计算使得发射强度最佳地满足这些目标的权重。有人认为,通过我们称之为级联解压缩的过程,使用培训的目标解决爆炸梯度的问题,并使损失功能表面更加光滑,因此导致更容易,培训更快,以及潜在的概括,神经网络。它还允许更容易地学习更深层次和经常性的网络结构。目标对重量的必要转换有额外的计算费用,这是在许多情况下可管理的。在目标空间中学习可以与现有的神经网络优化器相结合,以额外收益。实验结果表明了使用目标空间的速度,以及改进的泛化的示例,用于全连接的网络和卷积网络,以及调用和处理长时间序列的能力,并使用经常性网络进行自然语言处理。
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This paper presents SimCLR: a simple framework for contrastive learning of visual representations. We simplify recently proposed contrastive selfsupervised learning algorithms without requiring specialized architectures or a memory bank. In order to understand what enables the contrastive prediction tasks to learn useful representations, we systematically study the major components of our framework. We show that (1) composition of data augmentations plays a critical role in defining effective predictive tasks, (2) introducing a learnable nonlinear transformation between the representation and the contrastive loss substantially improves the quality of the learned representations, and (3) contrastive learning benefits from larger batch sizes and more training steps compared to supervised learning. By combining these findings, we are able to considerably outperform previous methods for self-supervised and semi-supervised learning on ImageNet. A linear classifier trained on self-supervised representations learned by Sim-CLR achieves 76.5% top-1 accuracy, which is a 7% relative improvement over previous state-ofthe-art, matching the performance of a supervised ResNet-50. When fine-tuned on only 1% of the labels, we achieve 85.8% top-5 accuracy, outperforming AlexNet with 100× fewer labels. 1
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Convolutional Neural Networks define an exceptionally powerful class of models, but are still limited by the lack of ability to be spatially invariant to the input data in a computationally and parameter efficient manner. In this work we introduce a new learnable module, the Spatial Transformer, which explicitly allows the spatial manipulation of data within the network. This differentiable module can be inserted into existing convolutional architectures, giving neural networks the ability to actively spatially transform feature maps, conditional on the feature map itself, without any extra training supervision or modification to the optimisation process. We show that the use of spatial transformers results in models which learn invariance to translation, scale, rotation and more generic warping, resulting in state-of-the-art performance on several benchmarks, and for a number of classes of transformations.
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Jitendra Malik once said, "Supervision is the opium of the AI researcher". Most deep learning techniques heavily rely on extreme amounts of human labels to work effectively. In today's world, the rate of data creation greatly surpasses the rate of data annotation. Full reliance on human annotations is just a temporary means to solve current closed problems in AI. In reality, only a tiny fraction of data is annotated. Annotation Efficient Learning (AEL) is a study of algorithms to train models effectively with fewer annotations. To thrive in AEL environments, we need deep learning techniques that rely less on manual annotations (e.g., image, bounding-box, and per-pixel labels), but learn useful information from unlabeled data. In this thesis, we explore five different techniques for handling AEL.
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通过卫星摄像机获取关于地球表面的大面积的信息使我们能够看到远远超过我们在地面上看到的更多。这有助于我们在检测和监测土地使用模式,大气条件,森林覆盖和许多非上市方面的地区的物理特征。所获得的图像不仅跟踪连续的自然现象,而且对解决严重森林砍伐的全球挑战也至关重要。其中亚马逊盆地每年占最大份额。适当的数据分析将有助于利用可持续健康的氛围来限制对生态系统和生物多样性的不利影响。本报告旨在通过不同的机器学习和优越的深度学习模型用大气和各种陆地覆盖或土地使用亚马逊雨林的卫星图像芯片。评估是基于F2度量完成的,而用于损耗函数,我们都有S形跨熵以及Softmax交叉熵。在使用预先训练的ImageNet架构中仅提取功能之后,图像被间接馈送到机器学习分类器。鉴于深度学习模型,通过传输学习使用微调Imagenet预训练模型的集合。到目前为止,我们的最佳分数与F2度量为0.927。
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Deep convolutional networks have proven to be very successful in learning task specific features that allow for unprecedented performance on various computer vision tasks. Training of such networks follows mostly the supervised learning paradigm, where sufficiently many input-output pairs are required for training. Acquisition of large training sets is one of the key challenges, when approaching a new task. In this paper, we aim for generic feature learning and present an approach for training a convolutional network using only unlabeled data. To this end, we train the network to discriminate between a set of surrogate classes. Each surrogate class is formed by applying a variety of transformations to a randomly sampled 'seed' image patch. In contrast to supervised network training, the resulting feature representation is not class specific. It rather provides robustness to the transformations that have been applied during training. This generic feature representation allows for classification results that outperform the state of the art for unsupervised learning on several popular datasets . While such generic features cannot compete with class specific features from supervised training on a classification task, we show that they are advantageous on geometric matching problems, where they also outperform the SIFT descriptor.
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最近对反向传播的近似(BP)减轻了BP的许多计算效率低下和与生物学的不兼容性,但仍然存在重要的局限性。此外,近似值显着降低了基准的准确性,这表明完全不同的方法可能更富有成果。在这里,基于在软冠军全网络中Hebbian学习的最新理论基础上,我们介绍了多层softhebb,即一种训练深神经网络的算法,没有任何反馈,目标或错误信号。结果,它通过避免重量传输,非本地可塑性,层更新的时间锁定,迭代平衡以及(自我)监督或其他反馈信号来实现效率,这在其他方法中是必不可少的。与最先进的生物学知识学习相比,它提高的效率和生物兼容性不能取得准确性的折衷,而是改善了准确性。 MNIST,CIFAR-10,STL-10和IMAGENET上最多五个隐藏层和添加的线性分类器,分别达到99.4%,80.3%,76.2%和27.3%。总之,SOFTHEBB显示出与BP的截然不同的方法,即对几层的深度学习在大脑中可能是合理的,并提高了生物学上的机器学习的准确性。
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近年来,最先进神经网络的参数的数量急剧增加。这种对大规模神经网络感兴趣的激增具有促使新的分布式培训策略的发展,从而实现了这种模型。一种这样的策略是模型平行分布式培训。不幸的是,模型 - 并行性遭受资源利用率差,导致资源浪费。在这项工作中,我们改进了最近的理想化模型 - 并行优化设置:本地学习。由于资源利用率差,我们在当地和全球学习之间介绍了一类中介战略,称为联锁反向化。这些策略保留了本地优化的许多计算效率优势,同时恢复全球优化实现的大部分任务性能。我们评估了我们对图像分类的策略和变压器语言模型,发现我们的策略一致地在任务绩效方面出现本地学习,并在培训效率方面进行全球学习。
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Convolutional neural networks are built upon the convolution operation, which extracts informative features by fusing spatial and channel-wise information together within local receptive fields. In order to boost the representational power of a network, several recent approaches have shown the benefit of enhancing spatial encoding. In this work, we focus on the channel relationship and propose a novel architectural unit, which we term the "Squeezeand-Excitation" (SE) block, that adaptively recalibrates channel-wise feature responses by explicitly modelling interdependencies between channels. We demonstrate that by stacking these blocks together, we can construct SENet architectures that generalise extremely well across challenging datasets. Crucially, we find that SE blocks produce significant performance improvements for existing state-ofthe-art deep architectures at minimal additional computational cost. SENets formed the foundation of our ILSVRC 2017 classification submission which won first place and significantly reduced the top-5 error to 2.251%, achieving a ∼25% relative improvement over the winning entry of 2016.
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最近的作品研究了在神经切线内核(NTK)制度中训练的广泛神经网络的理论和经验特性。鉴于生物神经网络比其人工对应物宽得多,因此我们认为NTK范围广泛的神经网络是生物神经网络的可能模型。利用NTK理论,我们从理论上说明梯度下降驱动层的重量更新与其输入活动相关性一致,并通过误差加权,并从经验上证明了结果在有限宽度的宽网络中也存在。对齐结果使我们能够制定一个生物动机的,无反向传播的学习规则,理论上等同于无限宽度网络中的反向传播。我们测试了馈电和经常性神经网络中基准问题的这些学习规则,并在宽网络中证明了与反向传播相当的性能。所提出的规则在低数据制度中特别有效,这在生物学习环境中很常见。
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分批归一化(BN)由归一化组成部分,然后是仿射转化,并且对于训练深神经网络至关重要。网络中每个BN的标准初始化分别设置了仿射变换量表,并将其转移到1和0。但是,经过训练,我们观察到这些参数从初始化中并没有太大变化。此外,我们注意到归一化过程仍然可以产生过多的值,这对于训练是不可能的。我们重新审视BN公式,并为BN提出了一种新的初始化方法和更新方法,以解决上述问题。实验旨在强调和证明适当的BN规模初始化对性能的积极影响,并使用严格的统计显着性测试进行评估。该方法可以与现有实施方式一起使用,没有额外的计算成本。源代码可在https://github.com/osu-cvl/revisiting-bninit上获得。
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