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How the AI-assisted discovery and synthesis of a ternary oxide highlights capability gaps in materials science
Energy & Materials | March 7, 2024

Exploratory synthesis has been the main generator of new inorganic materials for decades. However, our Edisonian and bias-prone processes of synthetic exploration alone are no longer sufficient in an age that demands rapid advances in materials development. In this work, we demonstrate an end-to-end attempt towards systematic, computer-aided discovery and laboratory synthesis of inorganic crystalline compounds as a modern alternative to purely exploratory synthesis. Our approach initializes materials discovery campaigns by autonomously mapping the synthetic feasibility of a chemical system using density functional theory with AI feedback. Following expert-driven down-selection of newly generated phases, we use solid-state synthesis and in situ characterization via hot-stage X-ray diffraction in order to realize new ternary oxide phases experimentally. We applied this strategy in six ternary transition-metal oxide chemistries previously considered well-explored, one of which culminated in the discovery of two novel phases of calcium ruthenates. Detailed characterization using room temperature X-ray powder diffraction, 4D-STEM and SQUID measurements identifies the structure and composition and confirms distinct properties, including distinct defect concentrations, of one of the new phases formed in our experimental campaigns. While the discovery of a new material guided by AI and DFT theory represents a milestone, our procedure and results also highlight a number of critical gaps in the process that can inform future efforts towards the improvement of AI-coupled methodologies. READ MORE

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An integrated autonomous simulation and human experimental workflow showing computer-aided discovery and experimental feedback to downselect candidate systems.
Event-driven data management with cloud computing for extensible materials acceleration platforms
Energy & Materials | March 1, 2024

The materials research community is increasingly using automation and artificial intelligence (AI) to accelerate research and development. A materials acceleration platform (MAP) typically encompasses several experimental techniques or instruments to establish a synthesis-characterization-evaluation workflow. With the advancement of workflow orchestration software and AI experiment design, the scope and complexity of MAPs are increasing, however each MAP typically operates as a standalone entity with dedicated experiment, compute, and database resources. The data from each MAP is thus siloed until subsequent efforts to integrate data into complex schema such as knowledge graphs. To lower the latency of data integration and establish an extensible community of MAPs, we must expand our automation efforts to include data handling that is decoupled from the resources of each MAP. Event-driven pipelines are well established in the computational community for building decoupled data processing systems. Such pipelines can be difficult to implement de novo due to their distributed nature and complex error handling. Fortunately, the broader computational science community has established a suite of cloud services that are well suited for this task. By leveraging cloud computing resources to establish event-driven data management, the MAP community can better realize the ideals of extensibility and interoperability in materials chemistry research. READ MORE

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Event Consumer/Producers image
History-agnostic battery degradation inference
Energy & Materials | March 1, 2024

Lithium-ion batteries (LIBs) have attracted widespread attention as an efficient energy storage device on electric vehicles (EV) to achieve emission-free mobility. However, the performance of LIBs deteriorates with time and usage, and the state of health of used batteries are difficult to quantify. Having accurate estimations of a battery’s remaining life across different life stages would benefit maintenance, safety, and serve as a means of qualifying used batteries for second-life applications. Since the full history of a battery may not always be available in downstream applications, in this study, we demonstrate a deep learning framework that enables dynamic degradation rate prediction, including both short-term and long-term forecasting, while requiring only the most recent battery usage information. Specifically, our model takes a rolling window of current and voltage time-series inputs, and predicts the near-term and long-term capacity fade via a recurrent neural network. We exhaustively benchmark our model against a naive extrapolating model by evaluating the error on reconstructing the discharge capacity profile under different settings. We show that our model’s performance in accurately inferring the battery’s degradation profile is agnostic with respect to cell cycling history and its current state of health. This approach can provide a promising path towards evaluating battery health in running vehicles, enhance edge-computing battery diagnostics, and determine the state of health for used batteries with unknown cycling histories. READ MORE

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history-agnostic battery degradation inference image
Data-driven Car Drag Coefficient Prediction with Depth and Normal Renderings
Human Interactive Driving | February 22, 2024

Generative AI models have made significant progress in automating the creation of 3D shapes, which has the potential to transform car design. In engineering design and optimization, evaluating engineering metrics is crucial. To make generative models performance-aware and enable them to create high-performing designs, surrogate modeling of these metrics is necessary. However, the currently used representations of 3D shapes either require extensive computational resources to learn or suffer from significant information loss, which impairs their effectiveness in surrogate modeling. To address this issue, we propose a new 2D representation of 3D shapes. We develop a surrogate drag model based on this representation to verify its effectiveness in predicting 3D car drag. We construct a diverse dataset of 4,535 high-quality 3D car meshes labeled by drag coefficients computed from computational fluid dynamics simulations to train our model. Our experiments demonstrate that our model can accurately and efficiently evaluate drag coefficients with an R^2 value above 0.84 for various car categories. Our model is implemented using deep neural networks, making it compatible with recent AI image generation tools (such as Stable Diffusion) and a significant step towards the automatic generation of drag-optimized car designs. Moreover, we demonstrate a case study using the proposed surrogate model to guide a diffusion-based deep generative model for drag-optimized car body synthesis. We have made the dataset and code publicly available at https://decode.mit.edu/projects/dragprediction/. READ MORE

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2D Representation of 3D Shapes
A Self-Improvable Polymer Discovery Framework Based on Conditional Generative Model (Preprint)
Energy & Materials | February 22, 2024

In this work, we introduce a polymer discovery platform designed to identify polymers with tailored properties efficiently, exemplified through the discovery of high-performance polymer electrolytes. The platform integrates three core components: a conditioned generative model, validation modules, and a feedback mechanism, creating a self-improving system for material innovation. To demonstrate the efficacy of this platform, it is used to identify polymer electrolyte materials with high ionic conductivity. A simple conditional generative model, based on the minGPT architecture, can effectively generate candidate polymers that exhibit a mean ionic conductivity that is significantly greater than those in the original training set. This approach, coupled with molecular dynamics simulations for validation and a specifically designed acquisition mechanism, allows the platform to refine its output iteratively. Notably, after the first iteration, we observed an increase in both the mean and the lower bound of the ionic conductivity of the new polymer candidates. The platform's effectiveness is underscored by the identification of 19 polymer repeating units, each displaying a computed ionic conductivity surpassing that of Polyethylene Oxide (PEO). The discovery of these polymers validates the platform's efficacy in identifying potential polymer materials. Acknowledging current limitations, future work will focus on enhancing modeling techniques, validation processes, and acquisition strategies, aiming for broader applicability in polymer science and machine learning. READ MORE

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Schematic illustration of the platform.
Causal AI Framework for Unit Selection in Optimizing Electric Vehicle Procurement
Human-Centered AI | February 21, 2024

Electric vehicles (EVs) are generally considered more environmentally sustainable than internal combustion engine vehicles (ICEVs). Government and policy makers may want to incentivize multi-vehicle households who, if they purchase a new EV, would use their EV to replace a large portion of their ICEV mileage. Therefore, it is important to analyze how EV procurement affects annual EV mileage for different households. Given that many relevant data, especially experimental data, are often unavailable in the real world, we need causal analysis tools to answer this question. Additionally, our aim is to compare the expected EV mileage of different combinations of vehicles a household owns. Observing multiple combinations in an individual household is impossible since only one combination can exist, making causal inference challenging. In this paper, we construct a causal AI framework utilizing counterfactual reasoning methods to address this issue. READ MORE

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causal dag
DiffusionNOCS: Managing Symmetry and Uncertainty in Sim2Real Multi-Modal Category-level Pose Estimation
Robotics | February 20, 2024

This paper addresses the challenging problem of category-level pose estimation. Current state-of-the-art methods for this task face challenges when dealing with symmetric objects and when attempting to generalize to new environments solely through synthetic data training. In this work, we address these challenges by proposing a probabilistic model that relies on diffusion to estimate dense canonical maps crucial for recovering partial object shapes as well as establishing correspondences essential for pose estimation. Furthermore, we introduce critical components to enhance performance by leveraging the strength of the diffusion models with multi-modal input representations. We demonstrate the effectiveness of our method by testing it on a range of real datasets. Despite being trained solely on our generated synthetic data, our approach achieves state-of-the-art performance and unprecedented generalization qualities, outperforming baselines, even those specifically trained on the target domain. READ MORE

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DiffusionNOCS
Personalizing Driver Safety Interfaces via Driver Cognitive Factors Inference
Human Interactive Driving | February 8, 2024

Recent advances in AI and intelligent vehicle technology hold promise to revolutionize mobility and transportation, in the form of advanced driving assistance (ADAS) interfaces. Although it is widely recognized that certain cognitive factors, such as impulsivity and inhibitory control, are related to risky driving behavior, play a significant role in on-road risk-taking, existing systems fail to leverage such factors. Varying levels of these cognitive factors could influence the effectiveness and acceptance of driver safety interfaces.


We demonstrate an approach for personalizing driver interaction via driver safety interfaces that are triggered based on a learned recurrent neural network. The network is trained from a population of human drivers to infer impulsivity and inhibitory control from recent driving behavior. Using a high-fidelity vehicle motion simulator, we demonstrate the ability to deduce these factors from driver behavior. We then use these inferred factors to make instantaneous determinations on whether or not to engage a driver safety interface. This interface aims to decrease a driver's speed during yellow lights and reduce their inclination to run through them. READ MORE

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framework overview
Personalized choice prediction with less user information
Human-Centered AI | January 30, 2024

While most models of human choice are linear to ease interpretation, it is not clear whether linear models are good models of human decision-making. And while prior studies have investigated how task conditions and group characteristics, such as personality or socio-demographic background, influence human decisions, no prior works have investigated how to use less personal information for choice prediction. We propose a deep learning model based on self-attention and cross-attention to model human decision making which takes into account both subject-specific information and task conditions. We show that our model can consistently predict human decisions more accurately than linear models and other baseline models while remaining interpretable. In addition, although a larger amount of subject-specific information will generally lead to more accurate choice prediction, collecting more surveys to gather subject background information is a burden to subjects, as well as costly and time-consuming. To address this, we introduce a training scheme that reduces the number of surveys that must be collected in order to achieve more accurate predictions. READ MORE

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image from personalized choice prediction article
A treatment of particle–electrolyte sharp interface fracture in solid-state batteries with multi-field discontinuities
Energy & Materials | January 1, 2024

In this work, we present a computational framework for coupled electro-chemo-(nonlinear) mechanics at the particle scale for solid-state batteries. The framework accounts for interfacial fracture between the active particles and solid electrolyte due to intercalation stresses. We extend discontinuous finite element methods for a sharp interface treatment of discontinuities in concentrations, fluxes, electric fields and in displacements, the latter arising from active particle–solid electrolyte interface fracture. We model the degradation in the charge transfer process that results from the loss of contact due to fracture at the electrolyte–active particle interfaces. Additionally, we account for the stress-dependent kinetics that can influence the charge transfer reactions and solid state diffusion. The discontinuous finite element approach does not require a conformal mesh. This offers the flexibility to construct arbitrary particle shapes and geometries that are based on design, or are obtained from microscopy images. The finite element mesh, however, can remain Cartesian, and independent of the particle goemetries. We demonstrate this computational framework on micro-structures that are representative of solid-state batteries with single and multiple anode and cathode particles. READ MORE

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multi-particle confirmation