子格式微型航空车(MAV)中的准确而敏捷的轨迹跟踪是具有挑战性的,因为机器人的小规模会引起大型模型不确定性,要求强大的反馈控制器,而快速的动力学和计算约束则阻止了计算上昂贵的策略的部署。在这项工作中,我们提出了一种在MIT SoftFly(一个子)MAV(0.7克)上进行敏捷和计算有效轨迹跟踪的方法。我们的策略采用了级联的控制方案,在该方案中,自适应态度控制器与受过训练的神经网络政策相结合,以模仿轨迹跟踪可靠的管模型模型预测控制器(RTMPC)。神经网络政策是使用我们最近的工作获得的,这使该政策能够保留RTMPC的稳健性,但以其计算成本的一小部分。我们通过实验评估我们的方法,即使在更具挑战性的操作中,达到均方根误差也低于1.8 cm,与我们先前的工作相比,最大位置误差减少了60%,并证明了对大型外部干扰的稳健性
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高维时空动力学通常可以在低维子空间中编码。用于建模,表征,设计和控制此类大规模系统的工程应用通常依赖于降低尺寸,以实时计算解决方案。降低维度的常见范例包括线性方法,例如奇异值分解(SVD)和非线性方法,例如卷积自动编码器(CAE)的变体。但是,这些编码技术缺乏有效地表示与时空数据相关的复杂性的能力,后者通常需要可变的几何形状,非均匀的网格分辨率,自适应网格化和/或参数依赖性。为了解决这些实用的工程挑战,我们提出了一个称为神经隐式流(NIF)的一般框架,该框架可以实现大型,参数,时空数据的网格不稳定,低级别表示。 NIF由两个修改的多层感知器(MLP)组成:(i)shapenet,它分离并代表空间复杂性,以及(ii)参数,该参数解释了任何其他输入复杂性,包括参数依赖关系,时间和传感器测量值。我们演示了NIF用于参数替代建模的实用性,从而实现了复杂时空动力学的可解释表示和压缩,有效的多空间质量任务以及改善了稀疏重建的通用性能。
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数据驱动模型发现中的中央挑战是存在隐藏或潜伏的变量,这些变量不会直接测量,而是动态重要。 TAKENS的定理提供了在可能随时间延迟信息中增加这些部分测量的条件,导致吸引物,这是对原始全状态系统的扩散逻辑。然而,回到原始吸引子的坐标变换通常是未知的,并且学习嵌入空间中的动态仍然是几十年的开放挑战。在这里,我们设计自定义深度AutoEncoder网络,以学习从延迟嵌入空间的坐标转换到一个新的空间,其中可以以稀疏,封闭的形式表示动态。我们在Lorenz,R \“Ossler和Lotka-Volterra系统上,从单个测量变量的学习动态展示了这种方法。作为一个具有挑战性的例子,我们从混乱的水车视频中提取的单个标量变量中学到一个洛伦兹类似物得到的建模框架结合了深入的学习来揭示可解释建模的非线性动力学(SINDY)的揭示有效坐标和稀疏识别。因此,我们表明可以同时学习闭合模型和部分的坐标系观察到的动态。
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自动化数据驱动的建模,直接发现系统的管理方程的过程越来越多地用于科学界。 Pysindy是一个Python包,提供用于应用非线性动力学(SINDY)方法的稀疏识别到数据驱动模型发现的工具。在Pysindy的这一主要更新中,我们实现了几种高级功能,使得能够从嘈杂和有限的数据中发现更一般的微分方程。延长候选术语库,用于识别致动系统,部分微分方程(PDE)和隐式差分方程。还实施了包括Sindy和合奏技术的整体形式的强大配方,以提高现实世界数据的性能。最后,我们提供了一系列新的优化算法,包括多元稀疏的回归技术和算法来强制执行和促进不等式约束和稳定性。这些更新在一起,可以在文献中尚未报告的全新SINDY模型发现能力,例如约束PDE识别和使用不同稀疏的回归优化器合并。
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时间序列数据的生成和分析与许多从经济学到流体力学的定量字段相关。在物理科学中,诸如亚稳态和连贯的组的结构,慢松弛过程,集体变量显性过渡途径或歧管流动流动的概率流动可能非常重视理解和表征系统的动力动力学和机械性质。 Deeptime是一种通用Python库,提供各种工具来估计基于时间序列数据的动态模型,包括传统的线性学习方法,例如马尔可夫状态模型(MSM),隐藏的马尔可夫模型和Koopman模型,以及内核和深度学习方法如vampnets和深msms。该库主要兼容Scikit-Searn,为这些不同的模型提供一系列估计器类,但与Scikit-Ge劳说相比,还提供了深度模型类,例如,在MSM的情况下,提供了多种分析方法来计算有趣的热力学,动力学和动态量,例如自由能,松弛时间和过渡路径。图书馆专为易于使用而设计,而且易于维护和可扩展的代码。在本文中,我们介绍了Deeptime软件的主要特征和结构。
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机器学习正迅速成为科学计算的核心技术,并有许多机会推进计算流体动力学领域。从这个角度来看,我们强调了一些潜在影响最高的领域,包括加速直接数值模拟,以改善湍流闭合建模,并开发增强的减少订单模型。我们还讨论了机器学习的新兴领域,这对于计算流体动力学以及应考虑的一些潜在局限性是有希望的。
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Identifying coordinate transformations that make strongly nonlinear dynamics approximately linear is a central challenge in modern dynamical systems. These transformations have the potential to enable prediction, estimation, and control of nonlinear systems using standard linear theory. The Koopman operator has emerged as a leading data-driven embedding, as eigenfunctions of this operator provide intrinsic coordinates that globally linearize the dynamics. However, identifying and representing these eigenfunctions has proven to be mathematically and computationally challenging. This work leverages the power of deep learning to discover representations of Koopman eigenfunctions from trajectory data of dynamical systems. Our network is parsimonious and interpretable by construction, embedding the dynamics on a low-dimensional manifold parameterized by these eigenfunctions. In particular, we identify nonlinear coordinates on which the dynamics are globally linear using a modified auto-encoder. We also generalize Koopman representations to include a ubiquitous class of systems that exhibit continuous spectra, ranging from the simple pendulum to nonlinear optics and broadband turbulence. Our framework parametrizes the continuous frequency using an auxiliary network, enabling a compact and efficient embedding, while connecting our models to half a century of asymptotics. In this way, we benefit from the power and generality of deep learning, while retaining the physical interpretability of Koopman embeddings.
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Manually analyzing spermatozoa is a tremendous task for biologists due to the many fast-moving spermatozoa, causing inconsistencies in the quality of the assessments. Therefore, computer-assisted sperm analysis (CASA) has become a popular solution. Despite this, more data is needed to train supervised machine learning approaches in order to improve accuracy and reliability. In this regard, we provide a dataset called VISEM-Tracking with 20 video recordings of 30s of spermatozoa with manually annotated bounding-box coordinates and a set of sperm characteristics analyzed by experts in the domain. VISEM-Tracking is an extension of the previously published VISEM dataset. In addition to the annotated data, we provide unlabeled video clips for easy-to-use access and analysis of the data. As part of this paper, we present baseline sperm detection performances using the YOLOv5 deep learning model trained on the VISEM-Tracking dataset. As a result, the dataset can be used to train complex deep-learning models to analyze spermatozoa. The dataset is publicly available at https://zenodo.org/record/7293726.
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This white paper lays out a vision of research and development in the field of artificial intelligence for the next decade (and beyond). Its denouement is a cyber-physical ecosystem of natural and synthetic sense-making, in which humans are integral participants$\unicode{x2014}$what we call ''shared intelligence''. This vision is premised on active inference, a formulation of adaptive behavior that can be read as a physics of intelligence, and which inherits from the physics of self-organization. In this context, we understand intelligence as the capacity to accumulate evidence for a generative model of one's sensed world$\unicode{x2014}$also known as self-evidencing. Formally, this corresponds to maximizing (Bayesian) model evidence, via belief updating over several scales: i.e., inference, learning, and model selection. Operationally, this self-evidencing can be realized via (variational) message passing or belief propagation on a factor graph. Crucially, active inference foregrounds an existential imperative of intelligent systems; namely, curiosity or the resolution of uncertainty. This same imperative underwrites belief sharing in ensembles of agents, in which certain aspects (i.e., factors) of each agent's generative world model provide a common ground or frame of reference. Active inference plays a foundational role in this ecology of belief sharing$\unicode{x2014}$leading to a formal account of collective intelligence that rests on shared narratives and goals. We also consider the kinds of communication protocols that must be developed to enable such an ecosystem of intelligences and motivate the development of a shared hyper-spatial modeling language and transaction protocol, as a first$\unicode{x2014}$and key$\unicode{x2014}$step towards such an ecology.
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Covid-19在大流行的不同阶段对公众构成了不成比例的心理健康后果。我们使用一种计算方法来捕获引发在线社区对大流行的焦虑的特定方面,并研究这些方面如何随时间变化。首先,我们使用主题分析在R/covid19 \ _support的Reddit帖子样本($ n $ = 86)中确定了九个焦虑(SOA)。然后,我们通过在手动注释的样本($ n $ = 793)上训练Reddit用户的焦虑来自动将SOA标记在较大的年代样本中($ n $ = 6,535)。 9个SOA与最近开发的大流行焦虑测量量表中的项目保持一致。我们观察到,在大流行的前八个月,Reddit用户对健康风险的担忧仍然很高。尽管案件激增稍后发生,但这些担忧却大大减少了。通常,随着大流行的进展,用户的语言披露了SOA的强烈强度。但是,在本研究涵盖的整个期间,人们对心理健康的担忧和未来稳步增长。人们还倾向于使用更强烈的语言来描述心理健康问题,而不是健康风险或死亡问题。我们的结果表明,尽管Covid-19逐渐削弱,但由于适当的对策而逐渐削弱了作为健康威胁,但该在线小组的心理健康状况并不一定会改善。我们的系统为人口健康和流行病学学者奠定了基础,以及时检查引起大流行焦虑的方面。
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