The method of color quantization and the technique of color spatial quantization based onKohonen neural network are presented in this paper.The later is actually a method of matrixquantization.Using Kohonen NN a palet...The method of color quantization and the technique of color spatial quantization based onKohonen neural network are presented in this paper.The later is actually a method of matrixquantization.Using Kohonen NN a palette and a codebook for color spatial quantization canbe easily obtained.Image compression techniques for digital areonautical maps must be cho-sen to allow rapid decompression and display while maximizing the compression ratio and im-age quality.The palette-based compression technique uses a palette and a codebook based onpalette for color spatial quantization as double look-up -tables,making image decompressionand display just a quick and simple process of looking up the two tables.展开更多
We study the possible topological phase in a one-dimensional（1D） quantum wire with an oscillating Rashba spin–orbital coupling in real space. It is shown that there are a pair of particle–hole symmetric gaps formi...We study the possible topological phase in a one-dimensional（1D） quantum wire with an oscillating Rashba spin–orbital coupling in real space. It is shown that there are a pair of particle–hole symmetric gaps forming in the bulk energy band and fractional boundary states residing in the gap when the system has an inversion symmetry. These states are topologically nontrivial and can be characterized by a quantized Berry phase ±π or nonzero Chern number through dimensional extension. When the Rashba spin–orbital coupling varies slowly with time, the system can pump out 2 charges in a pumping cycle because of the spin flip effect. This quantized pumping is protected by topology and is robust against moderate disorders as long as the disorder strength does not exceed the opened energy gap.展开更多
文摘The method of color quantization and the technique of color spatial quantization based onKohonen neural network are presented in this paper.The later is actually a method of matrixquantization.Using Kohonen NN a palette and a codebook for color spatial quantization canbe easily obtained.Image compression techniques for digital areonautical maps must be cho-sen to allow rapid decompression and display while maximizing the compression ratio and im-age quality.The palette-based compression technique uses a palette and a codebook based onpalette for color spatial quantization as double look-up -tables,making image decompressionand display just a quick and simple process of looking up the two tables.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.115074045 and 11204187)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20131284)
文摘We study the possible topological phase in a one-dimensional（1D） quantum wire with an oscillating Rashba spin–orbital coupling in real space. It is shown that there are a pair of particle–hole symmetric gaps forming in the bulk energy band and fractional boundary states residing in the gap when the system has an inversion symmetry. These states are topologically nontrivial and can be characterized by a quantized Berry phase ±π or nonzero Chern number through dimensional extension. When the Rashba spin–orbital coupling varies slowly with time, the system can pump out 2 charges in a pumping cycle because of the spin flip effect. This quantized pumping is protected by topology and is robust against moderate disorders as long as the disorder strength does not exceed the opened energy gap.
