Real-time air pollution monitoring is a valuable tool for public health and environmental surveillance. In recent years, there has been a dramatic increase in air pollution forecasting and monitoring research using artificial neural networks (ANNs). Most of the prior work relied on modeling pollutant concentrations collected from ground-based monitors and meteorological data for long-term forecasting of outdoor ozone, oxides of nitrogen, and PM2.5. Given that traditional, highly sophisticated air quality monitors are expensive and are not universally available, these models cannot adequately serve those not living near pollutant monitoring sites. Furthermore, because prior models were built on physical measurement data collected from sensors, they may not be suitable for predicting public health effects experienced from pollution exposure. This study aims to develop and validate models to nowcast the observed pollution levels using Web search data, which is publicly available in near real-time from major search engines. We developed novel machine learning-based models using both traditional supervised classification methods and state-of-the-art deep learning methods to detect elevated air pollution levels at the US city level, by using generally available meteorological data and aggregate Web-based search volume data derived from Google Trends. We validated the performance of these methods by predicting three critical air pollutants (ozone (O3), nitrogen dioxide (NO2), and fine particulate matter (PM2.5)), across ten major U.S. metropolitan statistical areas (MSAs) in 2017 and 2018.

Efficient data transfers over high-speed, long-distance shared networks require proper utilization of available network bandwidth. Using parallel TCP streams enables an application to utilize network parallelism and can improve transfer throughput; however, finding the optimum number of parallel TCP streams is challenging due to nondeterministic background traffic sharing the same network. Additionally, the non-stationary, multi-objectiveness, and partially-observable nature of network signals in the host systems add extra complexity in finding the current network condition. In this work, we present a novel approach to finding the optimum number of parallel TCP streams using deep reinforcement learning (RL). We devise a learning-based algorithm capable of generalizing different network conditions and utilizing the available network bandwidth intelligently. Contrary to rule-based heuristics that do not generalize well in unknown network scenarios, our RL-based solution can dynamically discover and adapt the parallel TCP stream numbers to maximize the network bandwidth utilization without congesting the network and ensure fairness among contending transfers. We extensively evaluated our RL-based algorithm's performance, comparing it with several state-of-the-art online optimization algorithms. The results show that our RL-based algorithm can find near-optimal solutions 40% faster while achieving up to 15% higher throughput. We also show that, unlike a greedy algorithm, our devised RL-based algorithm can avoid network congestion and fairly share the available network resources among contending transfers.

In this paper, we investigate the impact of neural networks (NNs) topology on adversarial robustness. Specifically, we study the graph produced when an input traverses all the layers of a NN, and show that such graphs are different for clean and adversarial inputs. We find that graphs from clean inputs are more centralized around highway edges, whereas those from adversaries are more diffuse, leveraging under-optimized edges. Through experiments on a variety of datasets and architectures, we show that these under-optimized edges are a source of adversarial vulnerability and that they can be used to detect adversarial inputs.

深度神经网络已用于多种成功的应用中。但是，由于包含数百万个参数，它们的高度复杂性质导致在延迟需求低的管道中部署期间有问题。结果，更希望获得在推理期间具有相同性能的轻型神经网络。在这项工作中，我们提出了一种基于重量的修剪方法，其中权重根据以前的迭代势头逐渐修剪。神经网络的每个层都根据其相对稀疏性分配了一个重要性值，然后在先前迭代中的重量幅度分配。我们在Alexnet，VGG16和Resnet50等网络上评估了我们的方法，其中包括图像分类数据集，例如CIFAR-10和CIFAR-100。我们发现，在准确性和压缩比方面，结果优于先前的方法。我们的方法能够在两个数据集上获得同一降解的相同降解的15％压缩。

确定点过程（DPP）是一个优雅的模型，可以为$ n $项目集合的每个子集分配概率。虽然传统上，DPP由对称内核矩阵进行参数化，从而消除了对称约束，从而导致非对称DPP（NDPP），从而导致建模功率和预测性能的显着改善。最近的工作研究了Markov Chain Monte Carlo（MCMC）对NDPPS的采样算法，该算法仅限于Size-$ K $子集（称为$ K $ -NDPPS）。但是，这种方法的运行时间在$ n $中是二次的，因此对于大规模设置而言，它是不可行的。在这项工作中，我们为$ k $ -ndpps提供了可扩展的MCMC采样算法，并具有低级内核，从而使运行时具有sublinear，in $ n $。我们的方法基于一种最新的NDPP排斥抽样算法，我们通过一种有效构建建议分布的新方法来增强该算法。此外，我们将可扩展的$ K $ -NDPP采样算法扩展到没有大小约束的情况下。我们最终的采样方法在内核等级中具有多项式时间复杂性，而现有方法的运行时为指数在等级中。通过对现实世界数据集的理论分析和实验，我们验证我们的可扩展近似采样算法比现有的$ k $ -ndpps和ndpps的现有采样方法快的阶数。

水生运动是生物学家和工程师感兴趣的经典流体结构相互作用（FSI）问题。求解完全耦合的FSI方程，用于不可压缩的Navier-Stokes和有限的弹性在计算上是昂贵的。在这种系统中，优化机器人游泳器设计通常涉及在已经昂贵的模拟之上繁琐的，无梯度的程序。为了应对这一挑战，我们提出了一种针对FSI的新颖，完全可区分的混合方法，该方法结合了2D直接数值模拟，用于游泳器的可变形固体结构和物理受限的神经网络替代物，以捕获流体的流体动力效应。对于游泳者身体的可变形实心模拟，我们使用来自计算机图形领域的最新技术来加快有限元方法（FEM）。对于流体模拟，我们使用经过基于物理损耗功能的U-NET体系结构来预测每个时间步骤的流场。使用沉浸式边界方法（IBM）在我们游泳器边界的边界周围采样了来自神经网络的压力和速度场输出，以准确有效地计算其游泳运动。我们证明了混合模拟器在2D Carangiform游泳器上的计算效率和可不同性。由于可怜性，该模拟器可用于通过基于直接梯度的优化浸入流体中的软体体系的控件设计。

在本文中，我们启动了对分类中低维对逆动力（LDAP）现象的严格研究。与经典设置不同，这些扰动仅限于尺寸$ k $的子空间，该子空间比功能空间的尺寸$ d $小得多。 $ k = 1 $的情况对应于所谓的通用对抗扰动（UAPS; Moosavi-Dezfooli等，2017）。首先，我们考虑在通用规律条件（包括RELU网络）下的二进制分类器，并根据任何子空间的愚蠢率计算分析下限。这些界限明确强调了愚蠢率对模型的点缘的依赖性（即，在测试点的输出与其梯度的$ L_2 $ norm的比率），以及给定子空间与该梯度的对齐模型W.R.T.的梯度输入。我们的结果为启发式方法的最新成功提供了有效产生低维对对抗性扰动的严格解释。最后，我们表明，如果决策区域紧凑，那么它将接受通用的对抗性扰动，其$ l_2 $ norm，比典型的$ \ sqrt {d} $倍乘以数据点的典型$ l_2 $ norm。我们的理论结果通过对合成和真实数据的实验证实。

已知神经网络对对抗性例子高度敏感。这些可能是由于不同的因素，例如随机初始化或学习问题中的虚假相关性。为了更好地理解这些因素，我们提供了对不同场景中对抗性鲁棒性的精确研究，从初始化到不同制度的培训结束以及中间场景，由于“懒惰”培训，初始化仍然起着作用。我们考虑具有二次靶标和无限样品的高维度中的过度参数化网络。我们的分析使我们能够确定近似（通过测试错误测量）和鲁棒性之间的新权衡，从而在测试误差改善时只能变得更糟，反之亦然。我们还展示了由于不当缩放的随机初始化，线性化的懒惰训练机制如何使鲁棒性恶化。通过数值实验说明了我们的理论结果。

从一个非常少数标记的样品中学习新颖的课程引起了机器学习区域的越来越高。最近关于基于元学习或转移学习的基于范例的研究表明，良好特征空间的获取信息可以是在几次拍摄任务上实现有利性能的有效解决方案。在本文中，我们提出了一种简单但有效的范式，该范式解耦了学习特征表示和分类器的任务，并且只能通过典型的传送学习培训策略从基类嵌入体系结构的特征。为了在每个类别内保持跨基地和新类别和辨别能力的泛化能力，我们提出了一种双路径特征学习方案，其有效地结合了与对比特征结构的结构相似性。以这种方式，内部级别对齐和级别的均匀性可以很好地平衡，并且导致性能提高。三个流行基准测试的实验表明，当与简单的基于原型的分类器结合起来时，我们的方法仍然可以在电感或转换推理设置中的标准和广义的几次射击问题达到有希望的结果。

Accurate simulation of soft mechanisms under dynamic actuation is critical for the design of soft robots. We address this gap with our differentiable simulation tool by learning the material parameters of our soft robotic fish. On the example of a soft robotic fish, we demonstrate an experimentally-verified, fast optimization pipeline for learning the material parameters from quasi-static data via differentiable simulation and apply it to the prediction of dynamic performance. Our method identifies physically plausible Young's moduli for various soft silicone elastomers and stiff acetal copolymers used in creation of our three different robotic fish tail designs. We show that our method is compatible with varying internal geometry of the actuators, such as the number of hollow cavities. Our framework allows high fidelity prediction of dynamic behavior for composite bi-morph bending structures in real hardware to millimeter-accuracy and within 3 percent error normalized to actuator length. We provide a differentiable and robust estimate of the thrust force using a neural network thrust predictor; this estimate allows for accurate modeling of our experimental setup measuring bollard pull. This work presents a prototypical hardware and simulation problem solved using our differentiable framework; the framework can be applied to higher dimensional parameter inference, learning control policies, and computational design due to its differentiable character.