This work presents an efficient analytical method for spur gear modelling based on the interpolation of precomputed power-law parameters to calculate contact forces. The motivation arises from the fact that, when a nonlinear contact expression is combined with the linear deformations of the tooth body, the resulting force must be obtained through an iterative procedure to ensure deformation compatibility, which increases computational cost. To overcome this, a preprocessing stage is introduced together with the assumption that, for a meshing situation, the force-penetration relation can be represented by a power-law combining the linear stiffnesses of the tooth bodies with the nonlinear contribution of local contact. In this stage, a database is generated by fitting the power-law parameters for all combinations of contacting points between the teeth. Then, during simulation, the position and rotation of the gears directly provide the penetration and active contact points, from which the corresponding parameters are interpolated within the database, and the force is evaluated through the power-law. This strategy eliminates the iterative compatibility procedure required in the traditional approach when nonlinear contacts are included, inherently reducing the computational time while preserving accuracy.
Closed-form analytical solutions for displacement, strain, and stress serve as essential benchmarks for validating numerical methods. This work constructs complete function sets that generate two classes of strong solutions to the governing partial differential equations of two-dimensional beams. The boundary conditions are of Neumann type, prescribing displacement derivatives (strains) or equivalently stresses along all surfaces. The proposed framework is demonstrated on orthotropic and isotropic beams, effectively reproducing continuous and discontinuous surface stresses. The results provide a versatile set of benchmark solutions for assessing beam mechanics models.
This article presents the development and implementation of incremental nonlinear dynamic inversion (INDI), integrated with a proportional-derivative (PD) controller, to enhance stability and reference tracking during the takeoff, hover, and landing phases of an eVTOL (electric vertical takeoff and landing) vehicle. Simulation results indicate that INDI, combined with a PD controller tuned with natural frequencies between 0.1 and 3.0 rad/s and damping ratios near 1.0 , yields an overshoot below 20% . The steady-state time is less than 2 s for the attitude variables and less than 10 s for altitude. The rise time (10–90 ± 10% variations), maintaining bounded tracking errors within the vertical-flight envelope considered. The study further includes hardware-in-the-loop experiments to evaluate the behavior of the control law implemented on an STM32F4 microcontroller. Finally, a simulation-based stability and robustness analysis confirms that the closed-loop system remains stable provided that model uncertainties remain moderate.
Systematic comparisons across theoretical predictions for the properties of dense matter, nuclear physics data, and astrophysical observations (also called meta-analyses) are performed. Existing predictions for symmetric nuclear and neutron matter properties are considered, and they are shown in this paper as an illustration of the present knowledge. Asymmetric matter is constructed assuming the isospin asymmetry quadratic approximation. It is employed to predict the pressure at twice saturation energy-density based only on nuclear-physics constraints, and we find it compatible with the one from the gravitational-wave community. To make our meta-analysis transparent, updated in the future, and to publicly share our results, the Python toolkit nucleardatapy is described and released here. Hence, this paper accompanies nucleardatapy, which simplifies access to nuclear-physics data, including theoretical calculations, experimental measurements, and astrophysical observations. This Python toolkit is designed to easily provide data for: i) predictions for uniform matter (from microscopic or phenomenological approaches); ii) correlation among nuclear properties induced by experimental and theoretical constraints; iii) measurements for finite nuclei (nuclear chart, charge radii, neutron skins or nuclear incompressibilities, etc.) and hypernuclei (single particle energies); and iv) astrophysical observations. This toolkit provides data in a unified format for easy comparison and provides new meta-analysis tools. It will be continuously developed, and we expect contributions from the community in our endeavor.
The Coherent Neutrino-Nucleus Interaction Experiment (CONNIE) aims to detect the coherent scattering (CE nu NS) of reactor antineutrinos off silicon nuclei using thick fully depleted high-resistivity silicon CCDs. Two Skipper-CCD sensors with subelectron readout noise capability were installed at the experiment next to the Angra-2 reactor in 2021, making CONNIE the first experiment to employ Skipper-CCDs for reactor neutrino detection. We report on the performance of the Skipper-CCDs, the new data processing, data quality, and event selection for CE nu NS interactions, which enable CONNIE to reach a record low detection threshold of 15 eV. The data were collected over 300 days in 2021-2022 and correspond to exposures of 14.9 g-days with the reactor-on and 3.5 g-days with the reactor-off. The difference between the reactor-on and off event rates shows no excess and yields upper limits for the neutrino interaction rates, comparable with previous CONNIE limits from standard CCDs and higher exposures. Searches for new neutrino interactions beyond the Standard Model improve the previous CONNIE limit on a simplified model with light vector mediators. A first dark matter (DM) search by diurnal modulation by CONNIE obtains the best limits on the DM-electron scattering cross section by a surface-level experiment. These promising results, obtained using a very small-mass sensor, illustrate the potential of Skipper-CCDs to probe rare neutrino interactions and motivate the plans to increase the detector mass in the near future.
