Computer aided automatic Extraction of drainage networks from DEMs can promote the efficiency of regional water resource prospecting and assessment in GIS. Extracting drainage networks from raster DEMs is a necessary requirement in many applications of GIS, and determining surface water flow direction is a fundamental problem. In a raster environment, surface water flow direction of each cell can be directed to the neighboring cell with the steepest downslope drop (The basic D8, deterministic eight-neighbour method), which is inadequate for routing flow over pits and flat areas. Several improved methods are proposed to assign flow direction of pits and flats, which typically use entirely different procedures for processing pits and flats without heuristic information. Being different from others, a method to treat pits and flats is proposed in this paper. The method is based on heuristic search, which can effectively handle both conditions. This method is implemented in Pascal and experiments are carried out on actual DEM data. The experimental results show that this approach are robust, computationally efficient, and avoid many of the problems associated with other methods
Four kinds of edible composite films based on chitosan combined with additional substances (konjac glucomannan, cassava starch, maltodextrin and gelatin) and the addition of lysozyme were prepared and used as packaging materials for Mongolian cheese. The prepared composite films were evaluated using scanning electron microscopy and Fourier transform infrared spectroscopy. The physicochemical properties of all chitosan composite films, including thickness, viscosity, opacity, color, moisture content, water vapor permeability, tensile strength and elongation at break, were measured. The results show that Konjac glucomannan–chitosan composite film presented the strongest mechanical property and highest transparency. The cassava starch–chitosan composite film presented the highest water barrier property. The study on the storage characteristics of Mongolian cheese was evaluated at 4 °C. The results show that the cheese packaging by cassava starch–chitosan composite film presented better treatment performance in maintaining the quality, reducing weight loss and delayering microbial growth.
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