The paper presents the results of a comprehensive monitoring of the polygon： ＂Odessa Region, north-western part of the Black Sea＂ for the period 2009-2011. It is shown that most of the copper and nickel is brought ...The paper presents the results of a comprehensive monitoring of the polygon： ＂Odessa Region, north-western part of the Black Sea＂ for the period 2009-2011. It is shown that most of the copper and nickel is brought into the sea from the catchment area, and zinc and cadmium are mainly of the autochthonous origin. It is found that in 2010, after heavy rains, the area of bottom sediments contaminated by copper and nickel was increased. The main source of copper in the sea is vast vineyards.展开更多
The authors discuss the partition of a finite set of points in the plane into empty convex polygons, and improve some upper bound and lower bound in the related enumeration problems.
Diffusion-limited aggregation （DLA） assumes that particles perform pure random walk at a finite tem- perature and aggregate when they come close enough and stick together. Although it is well known that DLA in two d...Diffusion-limited aggregation （DLA） assumes that particles perform pure random walk at a finite tem- perature and aggregate when they come close enough and stick together. Although it is well known that DLA in two dimensions results in a ramified fractal structure, how the particle shape influences the formed morphology is still un- clear. In this work, we perform the off-lattice two-dimensional DLA simulations with different particle shapes of triangle, quadrangle, pentagon, hexagon, and octagon, respectively, and compare with the results for circular particles. Our results indicate that different particle shapes only change the local structure, but have no effects on the global structure of the formed fractal duster. The local compactness decreases as the number of polygon edges increases.展开更多
文摘The paper presents the results of a comprehensive monitoring of the polygon： ＂Odessa Region, north-western part of the Black Sea＂ for the period 2009-2011. It is shown that most of the copper and nickel is brought into the sea from the catchment area, and zinc and cadmium are mainly of the autochthonous origin. It is found that in 2010, after heavy rains, the area of bottom sediments contaminated by copper and nickel was increased. The main source of copper in the sea is vast vineyards.
基金Project supported by the Natural Science Foundation of Hebei Province (No.19971).
文摘The authors discuss the partition of a finite set of points in the plane into empty convex polygons, and improve some upper bound and lower bound in the related enumeration problems.
基金Supported by the Hundred Talent Program of the Chinese Academy of Sciences (CAS)the National Natural Science Foundation of China under Grant Nos. 10974208, 11121403, 1083401401, and 91027045
文摘Diffusion-limited aggregation （DLA） assumes that particles perform pure random walk at a finite tem- perature and aggregate when they come close enough and stick together. Although it is well known that DLA in two dimensions results in a ramified fractal structure, how the particle shape influences the formed morphology is still un- clear. In this work, we perform the off-lattice two-dimensional DLA simulations with different particle shapes of triangle, quadrangle, pentagon, hexagon, and octagon, respectively, and compare with the results for circular particles. Our results indicate that different particle shapes only change the local structure, but have no effects on the global structure of the formed fractal duster. The local compactness decreases as the number of polygon edges increases.
