在整个计算科学中,越来越需要利用原始计算马力的持续改进,通过对蛮力的尺度锻炼的尺度增加,以增加网状元素数量的增加。例如,如果不考虑分子水平的相互作用,就不可能对纳米多孔介质的转运进行定量预测,即从紧密的页岩地层提取至关重要的碳氢化合物。同样,惯性限制融合模拟依赖于数值扩散来模拟分子效应,例如非本地转运和混合,而无需真正考虑分子相互作用。考虑到这两个不同的应用程序,我们开发了一种新颖的功能,该功能使用主动学习方法来优化局部细尺度模拟的使用来告知粗尺度流体动力学。我们的方法解决了三个挑战:预测连续性粗尺度轨迹,以推测执行新的精细分子动力学计算,动态地更新细度计算中的粗尺度,并量化神经网络模型中的不确定性。
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避免地下储层中的过度压力对于诸如二氧化碳和废水注射等应用至关重要。通过控制注入/提取来管理压力,由于地下的复杂异质性。异质性通常需要高保真物理模型来对Co $ _2 $命运做出预测。此外,精确表征异质性的情况会充满参数不确定性。考虑到异质性和不确定性,这都使这是对当前储层模拟器的计算密集型问题。为了解决这个问题,我们使用全物理模型和机器学习的可区分编程来确定防止关键储层位置过度压力的流体提取率。我们使用DPFEHM框架,该框架具有基于标准的两点通量有限量离散化的值得信赖的物理学,并且像机器学习模型一样自动差异化。我们的物理知识的机器学习框架使用卷积神经网络根据渗透率领域学习适当的提取率。我们还执行超参数搜索以提高模型的准确性。执行培训和测试方案,以评估使用物理知识的机器学习来管理储层压力的可行性。我们构建并测试了一个足够精确的模拟器,该模拟器的速度比基于物理的模拟器快400000倍,从而允许接近实时分析和鲁棒的不确定性量化。
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Simulating quantum channels is a fundamental primitive in quantum computing, since quantum channels define general (trace-preserving) quantum operations. An arbitrary quantum channel cannot be exactly simulated using a finite-dimensional programmable quantum processor, making it important to develop optimal approximate simulation techniques. In this paper, we study the challenging setting in which the channel to be simulated varies adversarially with time. We propose the use of matrix exponentiated gradient descent (MEGD), an online convex optimization method, and analytically show that it achieves a sublinear regret in time. Through experiments, we validate the main results for time-varying dephasing channels using a programmable generalized teleportation processor.
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Human activity recognition (HAR) using drone-mounted cameras has attracted considerable interest from the computer vision research community in recent years. A robust and efficient HAR system has a pivotal role in fields like video surveillance, crowd behavior analysis, sports analysis, and human-computer interaction. What makes it challenging are the complex poses, understanding different viewpoints, and the environmental scenarios where the action is taking place. To address such complexities, in this paper, we propose a novel Sparse Weighted Temporal Attention (SWTA) module to utilize sparsely sampled video frames for obtaining global weighted temporal attention. The proposed SWTA is comprised of two parts. First, temporal segment network that sparsely samples a given set of frames. Second, weighted temporal attention, which incorporates a fusion of attention maps derived from optical flow, with raw RGB images. This is followed by a basenet network, which comprises a convolutional neural network (CNN) module along with fully connected layers that provide us with activity recognition. The SWTA network can be used as a plug-in module to the existing deep CNN architectures, for optimizing them to learn temporal information by eliminating the need for a separate temporal stream. It has been evaluated on three publicly available benchmark datasets, namely Okutama, MOD20, and Drone-Action. The proposed model has received an accuracy of 72.76%, 92.56%, and 78.86% on the respective datasets thereby surpassing the previous state-of-the-art performances by a margin of 25.26%, 18.56%, and 2.94%, respectively.
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Energy consumption in buildings, both residential and commercial, accounts for approximately 40% of all energy usage in the U.S., and similar numbers are being reported from countries around the world. This significant amount of energy is used to maintain a comfortable, secure, and productive environment for the occupants. So, it is crucial that the energy consumption in buildings must be optimized, all the while maintaining satisfactory levels of occupant comfort, health, and safety. Recently, Machine Learning has been proven to be an invaluable tool in deriving important insights from data and optimizing various systems. In this work, we review the ways in which machine learning has been leveraged to make buildings smart and energy-efficient. For the convenience of readers, we provide a brief introduction of several machine learning paradigms and the components and functioning of each smart building system we cover. Finally, we discuss challenges faced while implementing machine learning algorithms in smart buildings and provide future avenues for research at the intersection of smart buildings and machine learning.
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The size of an individual cell type, such as a red blood cell, does not vary much among humans. We use this knowledge as a prior for classifying and detecting cells in images with only a few ground truth bounding box annotations, while most of the cells are annotated with points. This setting leads to weakly semi-supervised learning. We propose replacing points with either stochastic (ST) boxes or bounding box predictions during the training process. The proposed "mean-IOU" ST box maximizes the overlap with all the boxes belonging to the sample space with a class-specific approximated prior probability distribution of bounding boxes. Our method trains with both box- and point-labelled images in conjunction, unlike the existing methods, which train first with box- and then point-labelled images. In the most challenging setting, when only 5% images are box-labelled, quantitative experiments on a urine dataset show that our one-stage method outperforms two-stage methods by 5.56 mAP. Furthermore, we suggest an approach that partially answers "how many box-labelled annotations are necessary?" before training a machine learning model.
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Drone-camera based human activity recognition (HAR) has received significant attention from the computer vision research community in the past few years. A robust and efficient HAR system has a pivotal role in fields like video surveillance, crowd behavior analysis, sports analysis, and human-computer interaction. What makes it challenging are the complex poses, understanding different viewpoints, and the environmental scenarios where the action is taking place. To address such complexities, in this paper, we propose a novel Sparse Weighted Temporal Fusion (SWTF) module to utilize sparsely sampled video frames for obtaining global weighted temporal fusion outcome. The proposed SWTF is divided into two components. First, a temporal segment network that sparsely samples a given set of frames. Second, weighted temporal fusion, that incorporates a fusion of feature maps derived from optical flow, with raw RGB images. This is followed by base-network, which comprises a convolutional neural network module along with fully connected layers that provide us with activity recognition. The SWTF network can be used as a plug-in module to the existing deep CNN architectures, for optimizing them to learn temporal information by eliminating the need for a separate temporal stream. It has been evaluated on three publicly available benchmark datasets, namely Okutama, MOD20, and Drone-Action. The proposed model has received an accuracy of 72.76%, 92.56%, and 78.86% on the respective datasets thereby surpassing the previous state-of-the-art performances by a significant margin.
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Consider two brands that want to jointly test alternate web experiences for their customers with an A/B test. Such collaborative tests are today enabled using \textit{third-party cookies}, where each brand has information on the identity of visitors to another website. With the imminent elimination of third-party cookies, such A/B tests will become untenable. We propose a two-stage experimental design, where the two brands only need to agree on high-level aggregate parameters of the experiment to test the alternate experiences. Our design respects the privacy of customers. We propose an estimater of the Average Treatment Effect (ATE), show that it is unbiased and theoretically compute its variance. Our demonstration describes how a marketer for a brand can design such an experiment and analyze the results. On real and simulated data, we show that the approach provides valid estimate of the ATE with low variance and is robust to the proportion of visitors overlapping across the brands.
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数据驱动的湍流建模正在经历数据科学算法和硬件开发后的兴趣激增。我们讨论了一种使用可区分物理范式的方法,该方法将已知的物理学与机器学习结合起来,以开发汉堡湍流的闭合模型。我们将1D汉堡系统视为一种原型测试问题,用于建模以对流为主的湍流问题中未解决的术语。我们训练一系列模型,这些模型在后验损失函数上结合了不同程度的物理假设,以测试模型在一系列系统参数(包括粘度,时间和网格分辨率)上的疗效。我们发现,以部分微分方程形式的归纳偏差的约束模型包含已知物理或现有闭合方法会产生高度数据效率,准确和可推广的模型,并且表现优于最先进的基准。以物理信息形式添加结构还为模型带来了一定程度的解释性,可能为封闭建模的未来提供了垫脚石。
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受数字孪生系统的启发,开发了一个新型的实时数字双框架,以增强机器人对地形条件的感知。基于相同的物理模型和运动控制,这项工作利用了与真实机器人同步的模拟数字双重同步,以捕获和提取两个系统之间的差异信息,这两个系统提供了多个物理数量的高维线索,以表示代表差异建模和现实世界。柔软的,非刚性的地形会导致腿部运动中常见的失败,因此,视觉感知完全不足以估计地形的这种物理特性。我们使用了数字双重来开发可折叠性的估计,这通过动态步行过程中的物理互动来解决此问题。真实机器人及其数字双重双重测量之间的感觉测量的差异用作用于地形可折叠性分析的基于学习的算法的输入。尽管仅在模拟中受过培训,但学习的模型可以在模拟和现实世界中成功执行可折叠性估计。我们对结果的评估表明,对不同方案和数字双重的优势的概括,可在地面条件下可靠地检测到细微差别。
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