pinc
Domain-decoupled Physics-informed Neural Networks with Closed-form Gradients for Fast Model Learning of Dynamical Systems
Krauss, Henrik, Habich, Tim-Lukas, Bartholdt, Max, Seel, Thomas, Schappler, Moritz
Physics-informed neural networks (PINNs) are trained using physical equations and can also incorporate unmodeled effects by learning from data. PINNs for control (PINCs) of dynamical systems are gaining interest due to their prediction speed compared to classical numerical integration methods for nonlinear state-space models, making them suitable for real-time control applications. We introduce the domain-decoupled physics-informed neural network (DD-PINN) to address current limitations of PINC in handling large and complex nonlinear dynamical systems. The time domain is decoupled from the feed-forward neural network to construct an Ansatz function, allowing for calculation of gradients in closed form. This approach significantly reduces training times, especially for large dynamical systems, compared to PINC, which relies on graph-based automatic differentiation. Additionally, the DD-PINN inherently fulfills the initial condition and supports higher-order excitation inputs, simplifying the training process and enabling improved prediction accuracy. Validation on three systems - a nonlinear mass-spring-damper, a five-mass-chain, and a two-link robot - demonstrates that the DD-PINN achieves significantly shorter training times. In cases where the PINC's prediction diverges, the DD-PINN's prediction remains stable and accurate due to higher physics loss reduction or use of a higher-order excitation input. The DD-PINN allows for fast and accurate learning of large dynamical systems previously out of reach for the PINC.
Parameterisation of Reasoning on Temporal Markov Logic Networks
David, Victor, Fournier-S'niehotta, Raphaรซl, Travers, Nicolas
We aim at improving reasoning on inconsistent and uncertain data. We focus on knowledge-graph data, extended with time intervals to specify their validity, as regularly found in historical sciences. We propose principles on semantics for efficient Maximum A-Posteriori inference on the new Temporal Markov Logic Networks (TMLN) which extend the Markov Logic Networks (MLN) by uncertain temporal facts and rules. We examine total and partial temporal (in)consistency relations between sets of temporal formulae. Then we propose a new Temporal Parametric Semantics, which may combine several sub-functions, allowing to use different assessment strategies. Finally, we expose the constraints that semantics must respect to satisfy our principles.
The flying drones putting workers out of a job
Flying drones and robots now patrol distribution warehouses - they've become workhorses of the e-commerce era online that retailers can't do without. It is driving down costs but it is also putting people out of work: what price progress? It could be a scene from Blade Runner 2049; the flying drone hovers in the warehouse aisle, its spinning rotors filling the cavernous space with a buzzing whine. It edges close to the packages stacked on the shelf and scans them using onboard optical sensors, before whizzing off to its next assignment. But this is no sci-fi film, it's a warehouse in the US - one of around 250,000 throughout the country, many gargantuan in size: retail giant Walmart's smallest warehouse, for example, is larger than 17 football fields put together.