自1970年代初以来，已经开发并改进了质谱仪和不连贯的散射雷达（MSIS）模型家族。 MSI的最新版本是海军研究实验室（NRL）MSIS 2.0经验大气模型。 NRLMSIS 2.0提供物种密度，质量密度和温度估计作为位置和空间天气条件的功能。长期以来，MSIS模型一直是研究和运营社区中的大气模型的流行选择，但与许多模型一样，并未提供不确定性估计。在这项工作中，我们开发了基于机器学习（ML）的外层温度模型，该模型可与NRLMSIS 2.0一起使用，以相对于高保真卫星密度估计值校准其。我们的模型（称为MSIS-UQ）没有提供点估计，而是输出一个分布，该分布将使用称为校准误差评分的度量进行评估。我们表明，MSIS-UQ的DEMIAS nRLMSIS 2.0导致模型和卫星密度之间的差异减少25％，并且比太空力量的高精度卫星阻力模型更接近卫星密度。我们还通过生成物种密度，质量密度和温度的高度曲线来显示模型的不确定性估计功能。这明确证明了外层温度概率如何影响NRLMSIS 2.0内的密度和温度曲线。另一项研究显示，相对于单独的NRLMSIS 2.0，迅速过冷的能力提高了，从而增强了它可以捕获的现象。

机器学习（ML）通常被视为一种黑盒回归技术，无法提供相当大的科学见解。 ML模型是通用函数近似器，如果正确使用，则可以提供与用于拟合的地面数据集有关的科学信息。 ML比参数模型的好处是，没有预定义的基础函数限制可以建模的现象。在这项工作中，我们在三个数据集上开发了ML模型：太空环境技术（SET）高精度卫星阻力模型（HASDM）密度数据库，这是Jacchia-Bowman 2008经验热层密度模型（JB2008），Jacchia-Bowman 2008经验的空间端段匹配数据集，以及具有挑战性的Minisatellite有效载荷（Champ）的加速度计衍生的密度数据集。将这些ML模型与海军研究实验室质谱仪和不相互分的散射雷达（NRLMSIS 2.0）模型进行比较，以研究中热层中传感后冷却的存在。我们发现NRLMSIS 2.0和JB2008-ML都不能说明后冷却，因此在强烈的地磁风暴（例如2003年万圣节风暴）之后的时期内表现不佳。相反，HASDM-ML和Champ-ML确实显示了传感后冷却的证据，表明这种现象存在于原始数据集中。结果表明，根据位置和暴风雨强度，速度1-3天的密度降低可能会发生1--3天。

Generalisation to unseen contexts remains a challenge for embodied navigation agents. In the context of semantic audio-visual navigation (SAVi) tasks, the notion of generalisation should include both generalising to unseen indoor visual scenes as well as generalising to unheard sounding objects. However, previous SAVi task definitions do not include evaluation conditions on truly novel sounding objects, resorting instead to evaluating agents on unheard sound clips of known objects; meanwhile, previous SAVi methods do not include explicit mechanisms for incorporating domain knowledge about object and region semantics. These weaknesses limit the development and assessment of models' abilities to generalise their learned experience. In this work, we introduce the use of knowledge-driven scene priors in the semantic audio-visual embodied navigation task: we combine semantic information from our novel knowledge graph that encodes object-region relations, spatial knowledge from dual Graph Encoder Networks, and background knowledge from a series of pre-training tasks -- all within a reinforcement learning framework for audio-visual navigation. We also define a new audio-visual navigation sub-task, where agents are evaluated on novel sounding objects, as opposed to unheard clips of known objects. We show improvements over strong baselines in generalisation to unseen regions and novel sounding objects, within the Habitat-Matterport3D simulation environment, under the SoundSpaces task.

This paper analyzes $\ell_1$ regularized linear regression under the challenging scenario of having only adversarially corrupted data for training. We use the primal-dual witness paradigm to provide provable performance guarantees for the support of the estimated regression parameter vector to match the actual parameter. Our theoretical analysis shows the counter-intuitive result that an adversary can influence sample complexity by corrupting the irrelevant features, i.e., those corresponding to zero coefficients of the regression parameter vector, which, consequently, do not affect the dependent variable. As any adversarially robust algorithm has its limitations, our theoretical analysis identifies the regimes under which the learning algorithm and adversary can dominate over each other. It helps us to analyze these fundamental limits and address critical scientific questions of which parameters (like mutual incoherence, the maximum and minimum eigenvalue of the covariance matrix, and the budget of adversarial perturbation) play a role in the high or low probability of success of the LASSO algorithm. Also, the derived sample complexity is logarithmic with respect to the size of the regression parameter vector, and our theoretical claims are validated by empirical analysis on synthetic and real-world datasets.

Bayesian methods, distributionally robust optimization methods, and regularization methods are three pillars of trustworthy machine learning hedging against distributional uncertainty, e.g., the uncertainty of an empirical distribution compared to the true underlying distribution. This paper investigates the connections among the three frameworks and, in particular, explores why these frameworks tend to have smaller generalization errors. Specifically, first, we suggest a quantitative definition for "distributional robustness", propose the concept of "robustness measure", and formalize several philosophical concepts in distributionally robust optimization. Second, we show that Bayesian methods are distributionally robust in the probably approximately correct (PAC) sense; In addition, by constructing a Dirichlet-process-like prior in Bayesian nonparametrics, it can be proven that any regularized empirical risk minimization method is equivalent to a Bayesian method. Third, we show that generalization errors of machine learning models can be characterized using the distributional uncertainty of the nominal distribution and the robustness measures of these machine learning models, which is a new perspective to bound generalization errors, and therefore, explain the reason why distributionally robust machine learning models, Bayesian models, and regularization models tend to have smaller generalization errors.

The feasibility of collecting a large amount of expert demonstrations has inspired growing research interests in learning-to-drive settings, where models learn by imitating the driving behaviour from experts. However, exclusively relying on imitation can limit agents' generalisability to novel scenarios that are outside the support of the training data. In this paper, we address this challenge by factorising the driving task, based on the intuition that modular architectures are more generalisable and more robust to changes in the environment compared to monolithic, end-to-end frameworks. Specifically, we draw inspiration from the trajectory forecasting community and reformulate the learning-to-drive task as obstacle-aware perception and grounding, distribution-aware goal prediction, and model-based planning. Firstly, we train the obstacle-aware perception module to extract salient representation of the visual context. Then, we learn a multi-modal goal distribution by performing conditional density-estimation using normalising flow. Finally, we ground candidate trajectory predictions road geometry, and plan the actions based on on vehicle dynamics. Under the CARLA simulator, we report state-of-the-art results on the CARNOVEL benchmark.

Echo State Networks (ESN) are a type of Recurrent Neural Networks that yields promising results in representing time series and nonlinear dynamic systems. Although they are equipped with a very efficient training procedure, Reservoir Computing strategies, such as the ESN, require the use of high order networks, i.e. large number of layers, resulting in number of states that is magnitudes higher than the number of model inputs and outputs. This not only makes the computation of a time step more costly, but also may pose robustness issues when applying ESNs to problems such as Model Predictive Control (MPC) and other optimal control problems. One such way to circumvent this is through Model Order Reduction strategies such as the Proper Orthogonal Decomposition (POD) and its variants (POD-DEIM), whereby we find an equivalent lower order representation to an already trained high dimension ESN. The objective of this work is to investigate and analyze the performance of POD methods in Echo State Networks, evaluating their effectiveness. To this end, we evaluate the Memory Capacity (MC) of the POD-reduced network in comparison to the original (full order) ENS. We also perform experiments on two different numerical case studies: a NARMA10 difference equation and an oil platform containing two wells and one riser. The results show that there is little loss of performance comparing the original ESN to a POD-reduced counterpart, and also that the performance of a POD-reduced ESN tend to be superior to a normal ESN of the same size. Also we attain speedups of around $80\%$ in comparison to the original ESN.

Transformers have attained superior performance in natural language processing and computer vision. Their self-attention and feedforward layers are overparameterized, limiting inference speed and energy efficiency. Tensor decomposition is a promising technique to reduce parameter redundancy by leveraging tensor algebraic properties to express the parameters in a factorized form. Prior efforts used manual or heuristic factorization settings without hardware-aware customization, resulting in poor hardware efficiencies and large performance degradation. In this work, we propose a hardware-aware tensor decomposition framework, dubbed HEAT, that enables efficient exploration of the exponential space of possible decompositions and automates the choice of tensorization shape and decomposition rank with hardware-aware co-optimization. We jointly investigate tensor contraction path optimizations and a fused Einsum mapping strategy to bridge the gap between theoretical benefits and real hardware efficiency improvement. Our two-stage knowledge distillation flow resolves the trainability bottleneck and thus significantly boosts the final accuracy of factorized Transformers. Overall, we experimentally show that our hardware-aware factorized BERT variants reduce the energy-delay product by 5.7x with less than 1.1% accuracy loss and achieve a better efficiency-accuracy Pareto frontier than hand-tuned and heuristic baselines.

Reinforcement learning (RL) is a promising solution for autonomous vehicles to deal with complex and uncertain traffic environments. The RL training process is however expensive, unsafe, and time consuming. Algorithms are often developed first in simulation and then transferred to the real world, leading to a common sim2real challenge that performance decreases when the domain changes. In this paper, we propose a transfer learning process to minimize the gap by exploiting digital twin technology, relying on a systematic and simultaneous combination of virtual and real world data coming from vehicle dynamics and traffic scenarios. The model and testing environment are evolved from model, hardware to vehicle in the loop and proving ground testing stages, similar to standard development cycle in automotive industry. In particular, we also integrate other transfer learning techniques such as domain randomization and adaptation in each stage. The simulation and real data are gradually incorporated to accelerate and make the transfer learning process more robust. The proposed RL methodology is applied to develop a path following steering controller for an autonomous electric vehicle. After learning and deploying the real-time RL control policy on the vehicle, we obtained satisfactory and safe control performance already from the first deployment, demonstrating the advantages of the proposed digital twin based learning process.

将规则无缝整合到学习中（LFD）策略是启用AI代理的现实部署的关键要求。最近，信号时间逻辑（STL）已被证明是将规则作为时空约束的有效语言。这项工作使用蒙特卡洛树搜索（MCT）作为将STL规范集成到香草LFD策略中以提高约束满意度的一种手段。我们建议以STL鲁棒性值来增强MCT启发式，以使树的搜索偏向具有更高限制满意度的分支。虽然无域的方法可以应用于将STL规则在线整合到任何预训练的LFD算法中，但我们选择目标条件的生成对抗性模仿学习作为离线LFD策略。我们将提出的方法应用于规划轨迹的领域，用于在非较低机场周围的通用航空飞机。使用对现实世界数据进行训练的模拟器的结果显示了60％的性能比不使用STL启发式方法的基线LFD方法提高了性能。