Ultrathin and Optically Transparent Microwave Absorber Based on Flexible Silver Nanowire Film

The design of an optically transparent and flexible metamaterial absorber was presented and fabricated. For this purpose, we use two different patterned silver nanowire films separated by the space layer, forming a transparent sandwiched structure with an ultrathin thickness. By analyzing the equivalent circuit model and distribution of electric field and current, the absorption physical mechanism has been theoretically investigated. The results show that the structure can achieve above 0.8 absorptions from 6 GHz to 18 GHz, and at the same time, this absorber also can obtain wide-angle property. The optical transmittance of the fabricated absorber exceeds 82% in the visible band. The results demonstrate that transparency and flexibility are the additional benefits that make the proposed absorber suitable for various potential applications.

Synthesis and Singularity Analysis of N-UU Parallel Wrists: A Symmetric Space Approach

We report some recent advances in kinematics and singularity analysis of the mirror-symmetric N-UU parallel wrists using symmetric space theory. We show that both the finite displacement and infinitesimal singularity kinematics of a N-UU wrist are governed by the mirror symmetry property and half-angle property of the underlying motion manifold, which is a symmetric submanifold of the special Euclidean group SE(3). Our result is stronger than and may be considered a closure of Hunt's argument for instantaneous mirror symmetry in his pioneering exposition of constant velocity shaft couplings. Moreover, we show that the wrist can, to some extent, be treated as a spherical mechanism, even though dependent translation exists, and the singularity-free workspace of a N-UU wrist may be analytically derived. This leads to a straightforward optimal design for maximal singularity-free workspace.

A Simulation of the Dynamic Properties Impact Based on the Variable Pressure Angle of Ovoid Gear

This paper discussed some properties of ovoid gear. The gear is a kind of special gear that transformed from the non-circular gear, hence just like the non-circular gear it also has some unique properties itself. In the paper we did some research start from the transmission of non-circular gear and point out the variable working pressure angle property. Then toke the ovoid gear as an example to deduce the working pressure angle expression, and discusse the force between two separate tooth during the meshing process. After all those things has been done, a 3D model of ovoid gear was established under the help of Pro/E, and then imported it to the Adams to do some meshing simulation in order to find the contact force under the impact of variable working pressure angle.