Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
(A–D) Show the design of a tetrahedral space frame outlining the hierarchy from a single unit actuator (A) to a tessellation of tetrahedral modules (D). (E–H) Show the grid-based hierarchical designs using the same unit actuator (A) to build the square unit modules (E,G) and the tiling of these modules (F,H).
