tailieunhanh - Nanotechnology Science and Computation part 4

Tham khảo tài liệu 'nanotechnology science and computation part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Self-healing Tile Sets 69 the backward growth direction. This difficulty is compounded by our choice made for the convenience of being able to write the block transformation concisely to treat output sides uniformly for both weak and strong outputs. Consequently every output side has a strong bond and non-deterministic backward growth could be severe. Thankfully by padding all sides of the block with null bonds we can prevent the backward growth from continuing for more than a single tile - the bond tile. However all those null bonds make forward growth difficult for diagonal blocks and convergent blocks because the two pieces of information required to know the new block s type are not co-localized. The solution in this case is to project that information into the center of the tile by a non-committal growth process bond tiles the actual decision is then made in the center where the information can be combined. 4 Self-healing for Polyomino Tile Sets Tile sets produced by the 5 X 5 self-healing transformation have a lot of strong bonds even when the original tile set had relatively few. This elicits some concern from those familiar with physical self-assembly because it brings into question the assumption that growth occurs only from the seed tile and that all subsequent steps consist of the accretion of a single isolated tile at a time rather than by the aggregation of separately nucleated fragments. In the absence of the seed tile for the seed block one can consider aTAM growth from each of the other tiles in the tile set. Ideally such growth cannot proceed far thus supporting the accretion hypothesis in spirit if not in detail. However we are not so lucky with this 5 X 5 transformation. The worst offenders here are the strong blocks starting with first tile in the block s usual assembly sequence as a mock seed aTAM growth puts together the entire 25-tile block and possibly more. This is just asking for trouble. We therefore consider whether it is possible to .