序数模式的统计分析的最终目的是表征它们诱导的特征的分布。特别是,了解大类时间序列模型的对熵统计复杂性的联合分布将允许迄今无法获得的统计测试。在这个方向上工作,我们表征了Shannon经验的渐进分布,用于任何模型,在此模型中,真正的归一化熵既不为零也不为零。我们从中心极限定理(假设大时间序列),多元增量方法和其平均值的三阶校正获得了渐近分布。我们讨论了其他结果(精确,一阶和二阶校正)有关其准确性和数值稳定性的适用性。在建立有关香农熵的测试统计数据的一般框架内,我们提出了双边测试,该测试验证是否有足够的证据拒绝以下假设,即两个信号产生了具有相同Shannon熵的顺序模式。我们将此双边测试应用于来自三个城市(都柏林,爱丁堡和迈阿密)的每日最高温度时间序列,并获得了明智的结果。
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Compliance in actuation has been exploited to generate highly dynamic maneuvers such as throwing that take advantage of the potential energy stored in joint springs. However, the energy storage and release could not be well-timed yet. On the contrary, for multi-link systems, the natural system dynamics might even work against the actual goal. With the introduction of variable stiffness actuators, this problem has been partially addressed. With a suitable optimal control strategy, the approximate decoupling of the motor from the link can be achieved to maximize the energy transfer into the distal link prior to launch. However, such continuous stiffness variation is complex and typically leads to oscillatory swing-up motions instead of clear launch sequences. To circumvent this issue, we investigate decoupling for speed maximization with a dedicated novel actuator concept denoted Bi-Stiffness Actuation. With this, it is possible to fully decouple the link from the joint mechanism by a switch-and-hold clutch and simultaneously keep the elastic energy stored. We show that with this novel paradigm, it is not only possible to reach the same optimal performance as with power-equivalent variable stiffness actuation, but even directly control the energy transfer timing. This is a major step forward compared to previous optimal control approaches, which rely on optimizing the full time-series control input.
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In the Earth's magnetosphere, there are fewer than a dozen dedicated probes beyond low-Earth orbit making in-situ observations at any given time. As a result, we poorly understand its global structure and evolution, the mechanisms of its main activity processes, magnetic storms, and substorms. New Artificial Intelligence (AI) methods, including machine learning, data mining, and data assimilation, as well as new AI-enabled missions will need to be developed to meet this Sparse Data challenge.
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We developed a simulator to quantify the effect of changes in environmental parameters on plant growth in precision farming. Our approach combines the processing of plant images with deep convolutional neural networks (CNN), growth curve modeling, and machine learning. As a result, our system is able to predict growth rates based on environmental variables, which opens the door for the development of versatile reinforcement learning agents.
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We demonstrate the use of a probabilistic machine learning technique to develop stochastic parameterizations of atmospheric column-physics. After suitable preprocessing of NASA's Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA2) data to minimize the effects of high-frequency, high-wavenumber component of MERRA2 estimate of vertical velocity, we use generative adversarial networks to learn the probability distribution of vertical profiles of diabatic sources conditioned on vertical profiles of temperature and humidity. This may be viewed as an improvement over previous similar but deterministic approaches that seek to alleviate both, shortcomings of human-designed physics parameterizations, and the computational demand of the "physics" step in climate models.
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Artificial intelligence methods including deep neural networks (DNN) can provide rapid molecular classification of tumors from routine histology with accuracy that matches or exceeds human pathologists. Discerning how neural networks make their predictions remains a significant challenge, but explainability tools help provide insights into what models have learned when corresponding histologic features are poorly defined. Here, we present a method for improving explainability of DNN models using synthetic histology generated by a conditional generative adversarial network (cGAN). We show that cGANs generate high-quality synthetic histology images that can be leveraged for explaining DNN models trained to classify molecularly-subtyped tumors, exposing histologic features associated with molecular state. Fine-tuning synthetic histology through class and layer blending illustrates nuanced morphologic differences between tumor subtypes. Finally, we demonstrate the use of synthetic histology for augmenting pathologist-in-training education, showing that these intuitive visualizations can reinforce and improve understanding of histologic manifestations of tumor biology.
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从示范中学习(LFD)提供了一种方便的手段,可以在机器人固有坐标中获得示范时为机器人提供灵巧的技能。但是,长期和复杂技能中复杂错误的问题减少了其广泛的部署。由于大多数此类复杂的技能由组合的较小运动组成,因此将目标技能作为一系列紧凑的运动原语似乎是合理的。在这里,需要解决的问题是确保电动机以允许成功执行后续原始的状态结束。在这项研究中,我们通过提议学习明确的校正政策来关注这个问题,当时未达到原始人之间的预期过渡状态。校正策略本身是通过使用最先进的运动原始学习结构,条件神经运动原语(CNMP)来学习的。然后,学识渊博的校正政策能够以背景方式产生各种运动轨迹。拟议系统比学习完整任务的优点在模拟中显示了一个台式设置,其中必须以两个步骤将对象通过走廊推动。然后,通过为上身类人生物机器人配备具有在3D空间中的条上打结的技巧,显示了所提出的方法在现实世界中进行双重打结的适用性。实验表明,即使面对校正案例不属于人类示范集的一部分,机器人也可以执行成功的打结。
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在许多情况下,更简单的模型比更复杂的模型更可取,并且该模型复杂性的控制是机器学习中许多方法的目标,例如正则化,高参数调整和体系结构设计。在深度学习中,很难理解复杂性控制的潜在机制,因为许多传统措施并不适合深度神经网络。在这里,我们开发了几何复杂性的概念,该概念是使用离散的dirichlet能量计算的模型函数变异性的量度。使用理论论据和经验结果的结合,我们表明,许多常见的训练启发式方法,例如参数规范正规化,光谱规范正则化,平稳性正则化,隐式梯度正则化,噪声正则化和参数初始化的选择,都可以控制几何学复杂性,并提供一个统一的框架,以表征深度学习模型的行为。
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我们通过查看在弥漫表面上铸造的对象的阴影来研究个体的生物特征识别信息的问题。我们表明,通过最大似然分析,在代表性的情况下,阴影中的生物特征信息泄漏可以足够用于可靠的身份推断。然后,我们开发了一种基于学习的方法,该方法在实际设置中证明了这种现象,从而利用阴影中的微妙提示是泄漏的来源,而无需任何标记的真实数据。特别是,我们的方法依赖于构建由从每个身份的单个照片获得的3D面模型组成的合成场景。我们以完全无监督的方式将我们从合成数据中学到的知识转移到真实数据中。我们的模型能够很好地概括到真实的域,并且在场景中的几种变体都有坚固的范围。我们报告在具有未知几何形状和遮挡对象的场景中发生的身份分类任务中的高分类精度。
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开发有效的自动分类器将真实来源与工件分开,对于宽场光学调查的瞬时随访至关重要。在图像差异过程之后,从减法伪像的瞬态检测鉴定是此类分类器的关键步骤,称为真实 - 博格斯分类问题。我们将自我监督的机器学习模型,深入的自组织地图(DESOM)应用于这个“真实的模拟”分类问题。 DESOM结合了自动编码器和一个自组织图以执行聚类,以根据其维度降低的表示形式来区分真实和虚假的检测。我们使用32x32归一化检测缩略图作为底部的输入。我们展示了不同的模型训练方法,并发现我们的最佳DESOM分类器显示出6.6%的检测率,假阳性率为1.5%。 Desom提供了一种更细微的方法来微调决策边界,以确定与其他类型的分类器(例如在神经网络或决策树上构建的)结合使用时可能进行的实际检测。我们还讨论了DESOM及其局限性的其他潜在用法。
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