Influence of Geometric Parameters On Mechanical Response of Concentric Cylinders With Centrosymmetric Lattice

A design method of centrosymmetric lattice structure is proposed. The centrosymmetric lattice is applied to the lightweight design of concentric cylindrical structures. Combining homogenization method and finite element method, the advantage of centrosymmetric lattice concentric cylinder in reducing the maximum stress is verified, and the stress distribution of centrosymmetric lattice concentric cylinder is more uniform along the circumference; two kinds of centrosymmetric lattice solids are selected, and the parametric method is used to study the influence of three parameters on the static response of a centrosymmetric lattice concentric cylinder under axisymmetric surface pressure.The results show that the maximum stress of the central symmetric concentric cylinder is less than that of the parallel array lattice cylinder under axisymmetric surface pressure;the stress distribution of the cylinder under axisymmetric load is periodic along the circumference, and the stress distribution of the concentric cylinder is more uniform than that of the parallel array lattice while the centrosymmetric lattice is applied to the lightweight design of concentric cylinder; the maximum stress increases with the increase of inside thickness and decreases with the increase of outside thickness; the increase of lattice section size will reduce the stress of outside and lattice of concentric cylinder, while the maximum stress of inside is less affected by the size of lattice section.

Vacuum magnetic fields with exact quasisymmetry near a flux surface. Part 1. Solutions near an axisymmetric surface

While several results have pointed to the existence of exactly quasisymmetric fields on a surface (Garren & Boozer, Phys. Fluids B, vol. 3, 1991, pp. 2805–2821; 2822–2834; Plunk & Helander, J. Plasma Phys., vol. 84, 2018, 905840205), we have obtained the first such solutions using a vacuum surface expansion formalism. We obtain a single nonlinear parabolic partial differential equation for a function $\eta$ such the field strength satisfies $B = B(\eta )$ . Closed-form solutions are obtained in cylindrical, slab and isodynamic geometries. Numerical solutions of the full nonlinear equations in general axisymmetric toroidal geometry are obtained, resulting in a class of quasihelical local vacuum equilibria near an axisymmetric surface. The analytic models provide additional insight into general features of the nonlinear solutions, such as localization of the surface perturbations on the inboard side. The local solutions thus obtained can be continued globally only for special initial surfaces.

Elastic Half Space under Axisymmetric Surface Loading and Influence of Couple Stresses

This paper presents the complete elastic field of a half space under axisymmetric surface loads by taking the influence of material microstructures into account. A well-known couple stress theory is adopted to handle such small scale effect and the resulting governing equations are solved by the method of Hankel integral transform. A selected numerical quadrature is then applied to efficiently evaluate all involved integrals. A set of results is also reported to not only confirm the validity of established solutions but also demonstrate the capability of the selected mathematical model to simulate the size-dependent characteristic of the predicted response when the external and internal length scales are comparable.

Impact of Tropical Cyclone Initialization on Its Convection Development and Intensity: A Case Study of Typhoon Megi (2010)

This study investigates the impact of tropical cyclone (TC) initialization methods on TC intensity prediction under a framework coupling the Weather Research and Forecasting Model with the TC Centered-Local Ensemble Transform Kalman Filter (WRF TCC-LETKF). While the TC environments are constrained by assimilating the same environmental observations, two different initialization strategies, assimilating real dropsonde observations (the DP experiment) and synthetic axisymmetric surface wind structure (the VT experiment), are employed to construct the TC inner-core structure. These two experiments have distinct results on predicting the rapid intensification (RI) of Typhoon Megi (2010), which can be attributed to their different convective burst (CB) development. In DP, the assimilation of the dropsondes helps establish a realistic TC structure with asymmetry information, leading to scattered CB distribution and persistent RI with abundant moisture supply. In VT, assimilating the axisymmetric surface wind structure spins up the TC efficiently. However, the initially excessive CB coverage causes a too-early high-level warm core, and the reduced moisture supply hinders RI. The forecast results imply that if the TC structure is initialized using a scheme considering only the axisymmetric vortex structure, the RI potential can possibly be underestimated due to the inability to represent the realistic asymmetric structure. Finally, assimilation of both the real and synthetic data can be complementary, giving a strong TC initially that undergoes a longer RI period.