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Analytical results for uncertainty propagation through trained machine learning regression models

arXiv.org Machine Learning

Machine learning (ML) models are increasingly being used in metrology applications. However, for ML models to be credible in a metrology context they should be accompanied by principled uncertainty quantification. This paper addresses the challenge of uncertainty propagation through trained/fixed machine learning (ML) regression models. Analytical expressions for the mean and variance of the model output are obtained/presented for certain input data distributions and for a variety of ML models. Our results cover several popular ML models including linear regression, penalised linear regression, kernel ridge regression, Gaussian Processes (GPs), support vector machines (SVMs) and relevance vector machines (RVMs). We present numerical experiments in which we validate our methods and compare them with a Monte Carlo approach from a computational efficiency point of view. We also illustrate our methods in the context of a metrology application, namely modelling the state-of-health of lithium-ion cells based upon Electrical Impedance Spectroscopy (EIS) data


People are calling 700 AI gadget the worst piece of tech they've ever used - even though it was touted as the 'iPhone killer'

Daily Mail - Science & tech

Reviews are in for a tiny 700 wearable computer, less than 2 square-inches in size, made by two former Apple employees who promised a breakthrough'iPhone killer.' And they haven't been kind: Humane's AI Pin has been called'The Worst Product I've Ever Reviewed' garnering low 4-out-of-10 scored from major tech publications. The device -- which is worn on the user's lapel, answers spoken commands via AI, and projects a tiny screen onto their hand -- has been criticized for hardware that overheats in just'a couple of minutes,' AI that delivers'incorrect answers' and worse. Now, Humane's employees and engineers have admitted that the AI Pin, which also requires a 24 monthly subscription plan, is'frustrating sometimes' and that the harsh reviews have been'honest' and'solid.' It's yet to be seen if the public will prefer tapping an object on their chest as opposed to pulling their phone out of their pocket Some tech industry boosters lashed out at influential YouTuber reviewer Marques Brownlee, whose negative review of the AI Pin has 3.7 million views, accusing him of'carelessness' for'potentially killing someone else's nascent project' with his critique.


mSAIL: Milligram-Scale Multi-Modal Sensor Platform for Monarch Butterfly Migration Tracking

Communications of the ACM

Each fall, millions of monarch butterflies across the northern US and Canada migrate up to 4000km to overwinter in specific mountain peaks in central Mexico. To track monarchs precisely and study their navigation, a monarch tracker must obtain daily localization of the butterfly as it progresses on its 3-month journey. And, the tracker must perform this task while having a weight in the tens of milligrams (mg) and measuring a few millimeters (mm) in size to avoid interfering with the monarch's flight. This paper proposes mSAIL, 8 8 2.6 mm and 62 mg embedded system for monarch migration tracking, constructed using 8 prior custom-designed ICs providing solar energy harvesting, an ultra-low power processor, light/temperature sensors, power management, and a wireless transceiver, all integrated and 3D stacked on a micro PCB with an 8 8 mm printed antenna. The proposed system is designed to record and compress light and temperature data during the migration path while harvesting solar energy for energy autonomy, and wirelessly transmit the data at the overwintering site in Mexico, from which the daily location of the butterfly can be estimated using a deep learning-based localization algorithm. A 2-day trial experiment of mSAIL attached to a live butterfly in an outdoor botanical garden demonstrates the feasibility of individual butterfly localization and tracking.


Lacking support in battle with China, European solar firms head to U.S.

The Japan Times

European governments due to move to support their solar power manufacturers this week will be too late to stop solar panel-maker Meyer Burger packing up a German factory to send production to the United States. The plant in Freiberg in eastern Germany closed in mid-March with the loss of 500 jobs, as the Swiss-listed firm joined a growing list of European renewable energy manufacturing factories shutting down or relocating. In the past year, at least 10 have said they were in financial difficulties. On a recent visit to the site, giant white robotic arms hung dormant over empty wooden pallets as workers prepared the last production line for shutdown. Talks with the German federal government to try to secure a future for the factory ended without success in late March, a company spokesperson said.


Graph neural network-based surrogate modelling for real-time hydraulic prediction of urban drainage networks

arXiv.org Artificial Intelligence

Physics-based models are computationally time-consuming and infeasible for real-time scenarios of urban drainage networks, and a surrogate model is needed to accelerate the online predictive modelling. Fully-connected neural networks (NNs) are potential surrogate models, but may suffer from low interpretability and efficiency in fitting complex targets. Owing to the state-of-the-art modelling power of graph neural networks (GNNs) and their match with urban drainage networks in the graph structure, this work proposes a GNN-based surrogate of the flow routing model for the hydraulic prediction problem of drainage networks, which regards recent hydraulic states as initial conditions, and future runoff and control policy as boundary conditions. To incorporate hydraulic constraints and physical relationships into drainage modelling, physics-guided mechanisms are designed on top of the surrogate model to restrict the prediction variables with flow balance and flooding occurrence constraints. According to case results in a stormwater network, the GNN-based model is more cost-effective with better hydraulic prediction accuracy than the NN-based model after equal training epochs, and the designed mechanisms further limit prediction errors with interpretable domain knowledge. As the model structure adheres to the flow routing mechanisms and hydraulic constraints in urban drainage networks, it provides an interpretable and effective solution for data-driven surrogate modelling. Simultaneously, the surrogate model accelerates the predictive modelling of urban drainage networks for real-time use compared with the physics-based model.


A Survey on Data-Driven Fault Diagnostic Techniques for Marine Diesel Engines

arXiv.org Artificial Intelligence

Fault diagnosis in marine diesel engines is vital for maritime safety and operational efficiency.These engines are integral to marine vessels, and their reliable performance is crucial for safenavigation. Swift identification and resolution of faults are essential to prevent breakdowns,enhance safety, and reduce the risk of catastrophic failures at sea. Proactive fault diagnosisfacilitates timely maintenance, minimizes downtime, and ensures the overall reliability andlongevity of marine diesel engines. This paper explores the importance of fault diagnosis,emphasizing subsystems, common faults, and recent advancements in data-driven approachesfor effective marine diesel engine maintenance


MPCOM: Robotic Data Gathering with Radio Mapping and Model Predictive Communication

arXiv.org Artificial Intelligence

Robotic data gathering (RDG) is an emerging paradigm that navigates a robot to harvest data from remote sensors. However, motion planning in this paradigm needs to maximize the RDG efficiency instead of the navigation efficiency, for which the existing motion planning methods become inefficient, as they plan robot trajectories merely according to motion factors. This paper proposes radio map guided model predictive communication (MPCOM), which navigates the robot with both grid and radio maps for shape-aware collision avoidance and communication-aware trajectory generation in a dynamic environment. The proposed MPCOM is able to trade off the time spent on reaching goal, avoiding collision, and improving communication. MPCOM captures high-order signal propagation characteristics using radio maps and incorporates the map-guided communication regularizer to the motion planning block. Experiments in IRSIM and CARLA simulators show that the proposed MPCOM outperforms other benchmarks in both LOS and NLOS cases. Real-world testing based on car-like robots is also provided to demonstrate the effectiveness of MPCOM in indoor environments.


Simplex Decomposition for Portfolio Allocation Constraints in Reinforcement Learning

arXiv.org Artificial Intelligence

Portfolio optimization tasks describe sequential decision problems in which the investor's wealth is distributed across a set of assets. Allocation constraints are used to enforce minimal or maximal investments into particular subsets of assets to control for objectives such as limiting the portfolio's exposure to a certain sector due to environmental concerns. Although methods for constrained Reinforcement Learning (CRL) can optimize policies while considering allocation constraints, it can be observed that these general methods yield suboptimal results. In this paper, we propose a novel approach to handle allocation constraints based on a decomposition of the constraint action space into a set of unconstrained allocation problems. In particular, we examine this approach for the case of two constraints. For example, an investor may wish to invest at least a certain percentage of the portfolio into green technologies while limiting the investment in the fossil energy sector. We show that the action space of the task is equivalent to the decomposed action space, and introduce a new reinforcement learning (RL) approach CAOSD, which is built on top of the decomposition. The experimental evaluation on real-world Nasdaq-100 data demonstrates that our approach consistently outperforms state-of-the-art CRL benchmarks for portfolio optimization.


Randomized Exploration in Cooperative Multi-Agent Reinforcement Learning

arXiv.org Machine Learning

We present the first study on provably efficient randomized exploration in cooperative multi-agent reinforcement learning (MARL). We propose a unified algorithm framework for randomized exploration in parallel Markov Decision Processes (MDPs), and two Thompson Sampling (TS)-type algorithms, CoopTS-PHE and CoopTS-LMC, incorporating the perturbed-history exploration (PHE) strategy and the Langevin Monte Carlo exploration (LMC) strategy respectively, which are flexible in design and easy to implement in practice. For a special class of parallel MDPs where the transition is (approximately) linear, we theoretically prove that both CoopTS-PHE and CoopTS-LMC achieve a $\widetilde{\mathcal{O}}(d^{3/2}H^2\sqrt{MK})$ regret bound with communication complexity $\widetilde{\mathcal{O}}(dHM^2)$, where $d$ is the feature dimension, $H$ is the horizon length, $M$ is the number of agents, and $K$ is the number of episodes. This is the first theoretical result for randomized exploration in cooperative MARL. We evaluate our proposed method on multiple parallel RL environments, including a deep exploration problem (\textit{i.e.,} $N$-chain), a video game, and a real-world problem in energy systems. Our experimental results support that our framework can achieve better performance, even under conditions of misspecified transition models. Additionally, we establish a connection between our unified framework and the practical application of federated learning.


Molecular relaxation by reverse diffusion with time step prediction

arXiv.org Machine Learning

Molecular relaxation, finding the equilibrium state of a non-equilibrium structure, is an essential component of computational chemistry to understand reactivity. Classical force field methods often rely on insufficient local energy minimization, while neural network force field models require large labeled datasets encompassing both equilibrium and non-equilibrium structures. As a remedy, we propose MoreRed, molecular relaxation by reverse diffusion, a conceptually novel and purely statistical approach where non-equilibrium structures are treated as noisy instances of their corresponding equilibrium states. To enable the denoising of arbitrarily noisy inputs via a generative diffusion model, we further introduce a novel diffusion time step predictor. Notably, MoreRed learns a simpler pseudo potential energy surface instead of the complex physical potential energy surface. It is trained on a significantly smaller, and thus computationally cheaper, dataset consisting of solely unlabeled equilibrium structures, avoiding the computation of non-equilibrium structures altogether. We compare MoreRed to classical force fields, equivariant neural network force fields trained on a large dataset of equilibrium and non-equilibrium data, as well as a semi-empirical tight-binding model. To assess this quantitatively, we evaluate the root-mean-square deviation between the found equilibrium structures and the reference equilibrium structures as well as their DFT energies.