Gridless Solution Method for Two-Dimensional Unsteady Flow

AbstractThe main purpose of this paper is to develop a gridless method for unsteady flow simulation. A quadrantal point infilling strategy is developed to generate point and combine clouds of points automatically. A point-moving algorithm is introduced to ensure the clouds of points following the movements of body boundaries. A dual time method for solving the two-dimensional Euler equations in Arbitrary Lagrangian-Eulerian (ALE) formulation is presented. Dual time method allows the real-time step to be chosen on the basis of accuracy rather than stability. It also permits the acceleration techniques, which are commonly used to speed up steady flow calculations, to be used when marching the equations in pseudo time. The spatial derivatives, which are used to estimating the inviscid flux, are directly approximated by using local least-squares curve method. An explicit multistage Runge-Kutta algorithm is used to advance the flow equations in pseudo time. In order to accelerate the solution to convergence, local time stepping technique and residual averaging are employed. The results of NACA0012 airfoil in transonic steady flow are presented to verify the accuracy of the present spatial discretization method. Finally, two AGARD standard test cases in which NACA0012 airfoil and NACA64A010 airfoil oscillate in transonic flow are simulated. The computational results are compared with the experimental data to demonstrate the validity and practicality of the presented method

19.2% Efficient InP Heterojunction Solar Cell with Electron-Selective TiO2 Contact.

We demonstrate an InP heterojunction solar cell employing an ultrathin layer (∼10 nm) of amorphous TiO2 deposited at 120 °C by atomic layer deposition as the transparent electron-selective contact. The TiO2 film selectively extracts minority electrons from the conduction band of p-type InP while blocking the majority holes due to the large valence band offset, enabling a high maximum open-circuit voltage of 785 mV. A hydrogen plasma treatment of the InP surface drastically improves the long-wavelength response of the device, resulting in a high short-circuit current density of 30.5 mA/cm2 and a high power conversion efficiency of 19.2%

Simulation and Experimental Analyses on Quasi-Static and Dynamic Performances of Four-Star Cellular Structure

A novel four-star cellular structure (FSCS) is proposed. Firstly, relative density of FSCS, regular octagons and regular hexagons are obtained accordingly. Then, their in-plane quasi-static and dynamic performances are conducted under the premise of equal number of cells, equal mass and equal relative density by adopting Hyperworks and Ls-Dyna software. Macroscopic deformation processes indicate that FSCS, regular octagons and regular hexagons are presented as "compression-shrinkage" negative Poisson\u27s ratio deformation mode, "V" deformation mode and "X" deformation mode, respectively. Subsequently, size effects of unit cell are carried out, and as the number of cell layers reaches no less than 9, platform stress of FSCS gradually tends to be stable. To verify the accuracy of finite element (FE) simulation models, quasi-static compression test is executed on three-dimensional FSCS. The results indicate that FE simulation results agree well with experimental predictions, and the proposed FSCS is equipped with superior energy absorption capability

CoBigICP: Robust and Precise Point Set Registration using Correntropy Metrics and Bidirectional Correspondence

In this paper, we propose a novel probabilistic variant of iterative closest point (ICP) dubbed as CoBigICP. The method leverages both local geometrical information and global noise characteristics. Locally, the 3D structure of both target and source clouds are incorporated into the objective function through bidirectional correspondence. Globally, error metric of correntropy is introduced as noise model to resist outliers. Importantly, the close resemblance between normal-distributions transform (NDT) and correntropy is revealed. To ease the minimization step, an on-manifold parameterization of the special Euclidean group is proposed. Extensive experiments validate that CoBigICP outperforms several well-known and state-of-the-art methods.Comment: 6 pages, 4 figures. Accepted to IROS202