What Matters: Agreement Between U.S. Courts of Appeals Judges

Federal courts are a mainstay of the justice system in the United States. In this study, we analyze 387,898 cases from U.S. Courts of Appeals, where judges are randomly assigned to panels of three. We predict which judge dissents against co-panelists and analyze the dominant features that predict such dissent with a particular attention to the biographical features that judges share. Random forest, a method developed in Breiman (2001), achieves the best classification. Dissent is predominantly driven by case features, though personal features also predict agreement

Performance Portable Solid Mechanics via Matrix-Free pp-Multigrid

Finite element analysis of solid mechanics is a foundational tool of modern engineering, with low-order finite element methods and assembled sparse matrices representing the industry standard for implicit analysis. We use performance models and numerical experiments to demonstrate that high-order methods greatly reduce the costs to reach engineering tolerances while enabling effective use of GPUs. We demonstrate the reliability, efficiency, and scalability of matrix-free $p$-multigrid methods with algebraic multigrid coarse solvers through large deformation hyperelastic simulations of multiscale structures. We investigate accuracy, cost, and execution time on multi-node CPU and GPU systems for moderate to large models using AMD MI250X (OLCF Crusher), NVIDIA A100 (NERSC Perlmutter), and V100 (LLNL Lassen and OLCF Summit), resulting in order of magnitude efficiency improvements over a broad range of model properties and scales. We discuss efficient matrix-free representation of Jacobians and demonstrate how automatic differentiation enables rapid development of nonlinear material models without impacting debuggability and workflows targeting GPUs

Review on the influence of process parameters in incremental sheet forming

Incremental sheet forming (ISF) is a relatively new flexible forming process. ISF has excellent adaptability to conventional milling machines and requires minimum use of complex tooling, dies and forming press, which makes the process cost-effective and easy to automate for various applications. In the past two decades, extensive research on ISF has resulted in significant advances being made in fundamental understanding and development of new processing and tooling solutions. However, ISF has yet to be fully implemented to mainstream high-value manufacturing industries due to a number of technical challenges, all of which are directly related to ISF process parameters. This paper aims to provide a detailed review of the current state-of-the-art of ISF processes in terms of its technological capabilities and specific limitations with discussions on the ISF process parameters and their effects on ISF processes. Particular attention is given to the ISF process parameters on the formability, deformation and failure mechanics, springback and accuracy and surface roughness. This leads to a number of recommendations that are considered essential for future research effort

Does the Debate on Stress Effect Lead Evacuation Simulation Models to Different Performances?

There exists a long time debate over the rational state of the evacuees in the evacuation simulation. Sime et al. insisted that the evacuees behave rationally in most cases. Following this argument Arthur and Passini concluded that if a setting works well under normal conditions, it will have a better chance of working well in emergency conditions. Such an argument for rational decision-making makes statistical models, such as Utility Maximizing Model (UMM), acting as proper framework for choice modelling in evacuation. However, on the other side, some people pointed out that there exists panic in the evacuation and bounded rationality theory, represented by pruned Decision Tree Model (DTM), should be adapted in choice modelling instead. Such a debate over stress effect causes hesitations and uncertainties when researchers try to select a proper model framework for their practical simulation. This study compared the performances (prediction accuracies) of the UMM and DTM with the same set of choice data collected in a virtual evacuation experiment. With a similar level of performance on both sides, it is suggested that the on-going debate does NOT bring any difference to the choice modelling in practical evacuation simulation. It is time to improve the performance rather than to continue the debate

First-principles studies of atomic dynamics in tetrahedrite thermoelectrics

Cu12Sb4S13-based tetrahedrites are high-performance thermoelectrics that contain earth-abundant and environmentally friendly elements. At present, the mechanistic understanding of their low lattice thermal conductivity (<1 W m−1 K−1 at 300 K) remains limited. This work applies first-principles molecular dynamics simulations, along with inelastic neutron scattering (INS) experiments, to study the incoherent and coherent atomic dynamics in Cu10.5NiZn0.5Sb4S13, in order to deepen our insight into mechanisms of anomalous dynamic behavior and low lattice thermal conductivity in tetrahedrites. Our study of incoherent dynamics reveals the anomalous “phonon softening upon cooling” behavior commonly observed in inelastic neutron scattering data. By examining the dynamic Cu-Sb distances inside the Sb[CuS3]Sb cage, we ascribe softening to the decreased anharmonic “rattling” of Cu in the cage. On the other hand, our study of coherent dynamics reveals that acoustic modes are confined in a small region of dynamic scattering space, which we hypothesize leads to a minimum phonon mean free path. By assuming a Debye model, we obtain a lattice minimum thermal conductivity value consistent with experiments. We believe this study furthers our understanding of the atomic dynamics of tetrahedrite thermoelectrics and will more generally help shed light on the origin of intrinsically low lattice thermal conductivity in these and other structurally similar materials