The spatial receptive fields of simple cells in mammalian striate cortex have been characterizd as being localized,oriented,and band pass detectors.These receptive fields produced a sparse distribution of output activity in response to natural image.It shows a model of sparse coding with overcomplete basis sets in the population of simple cells from the physical process of image detection,and gives coding representation of image in realistic visual environment.

Two dimensional random lattice model has been applied to spin glass system CuMn using Monte Carlo method. A new, method was developed for quick producing the 2D random lattice. Physical quantities susceptibility and specific heat were calculated under various conditions. The finite size problem was also tackled.