Mechanism and modeling of the land subsidence are complex because of the complicate geological background in Beijing, China. This paper analyzed the spatial relationship between land subsidence and three factors, incl...Mechanism and modeling of the land subsidence are complex because of the complicate geological background in Beijing, China. This paper analyzed the spatial relationship between land subsidence and three factors, including the change of groundwater level, the thickness of compressible sediments and the building area by using remote sensing and GIS tools in the upper-middle part of alluvial-proluvial plain fan of the Chaobai River in Beijing. Based on the spatial analysis of the land subsidence and three factors, there exist significant non-linear relationship between the vertical displacement and three factors. The Back Propagation Neural Network (BPN) model combined with Genetic Algorithm (GA) was used to simulate regional distribution of the land subsidence. Results showed that at field scale, the groundwater level and land subsidence showed a significant linear relationship. However, at regional scale, the spatial distribution of groundwater depletion funnel did not overlap with the land subsidence funnel. As to the factor of compressible strata, the places with the biggest compressible strata thickness did not have the largest vertical displacement. The distributions of building area and land subsidence have no obvious spatial relationships. The BPN-GA model simulation results illustrated that the accuracy of the trained model during fifty years is acceptable with an error of 51% of verification data less than 20 mm and the average of the absolute error about 32 mm. The BPN model could be utilized to simulate the general distribution of land subsidence in the study area. Overall, this work contributes to better understand the complex relationship between the land subsidence and three influencing factors. And the distribution of the land subsidence can be simulated by the trained BPN-GA model with the limited available dada and acceptable accuracy.展开更多
为了保持南美白对虾的品质,研究采用静止空气冻结(static air freezing, SAF)、液体浸渍冻结(immersion chilling and freezing, ICF)、真空包装联用静止空气冻结和真空包装联用液体浸渍冻结4种不同的冻结方式分别处理新鲜的南美白对虾...为了保持南美白对虾的品质,研究采用静止空气冻结(static air freezing, SAF)、液体浸渍冻结(immersion chilling and freezing, ICF)、真空包装联用静止空气冻结和真空包装联用液体浸渍冻结4种不同的冻结方式分别处理新鲜的南美白对虾,并以理化指标、冻结速率和扫描电镜为评价指标,研究不同冻结方式对南美白对虾品质的影响。结果表明:不同冻结方式处理后的南美白对虾冻结速率由快到慢依次为单一浸渍冻结>真空包装联用液体浸渍冻结>单一空气冻结>真空包装联用空气冻结;4种冻结方式处理的南美白对虾酸碱度(pH值)、肌肉组织恢复性及弹性、多酚氧化酶活性(PPO)、盐溶性蛋白含量均低于新鲜的南美白对虾,其中,真空包装联用液体浸渍冻结组的pH、肌肉组织恢复性及弹性、PPO、盐溶性蛋白含量降低最慢;微观扫描电镜观察真空包装联用液体浸渍冻结组对南美白对虾肌肉纤维的损伤最小。真空包装联用浸渍冻结技术更有利于南美白对虾冻结品质的保持。展开更多
基金Under the auspices of National Natural Science Foundation of China(No.41201420,41130744)Beijing Nova Program(No.Z111106054511097)Foundation of Beijing Municipal Commission of Education(No.KM201110028016)
文摘Mechanism and modeling of the land subsidence are complex because of the complicate geological background in Beijing, China. This paper analyzed the spatial relationship between land subsidence and three factors, including the change of groundwater level, the thickness of compressible sediments and the building area by using remote sensing and GIS tools in the upper-middle part of alluvial-proluvial plain fan of the Chaobai River in Beijing. Based on the spatial analysis of the land subsidence and three factors, there exist significant non-linear relationship between the vertical displacement and three factors. The Back Propagation Neural Network (BPN) model combined with Genetic Algorithm (GA) was used to simulate regional distribution of the land subsidence. Results showed that at field scale, the groundwater level and land subsidence showed a significant linear relationship. However, at regional scale, the spatial distribution of groundwater depletion funnel did not overlap with the land subsidence funnel. As to the factor of compressible strata, the places with the biggest compressible strata thickness did not have the largest vertical displacement. The distributions of building area and land subsidence have no obvious spatial relationships. The BPN-GA model simulation results illustrated that the accuracy of the trained model during fifty years is acceptable with an error of 51% of verification data less than 20 mm and the average of the absolute error about 32 mm. The BPN model could be utilized to simulate the general distribution of land subsidence in the study area. Overall, this work contributes to better understand the complex relationship between the land subsidence and three influencing factors. And the distribution of the land subsidence can be simulated by the trained BPN-GA model with the limited available dada and acceptable accuracy.
文摘为了保持南美白对虾的品质,研究采用静止空气冻结(static air freezing, SAF)、液体浸渍冻结(immersion chilling and freezing, ICF)、真空包装联用静止空气冻结和真空包装联用液体浸渍冻结4种不同的冻结方式分别处理新鲜的南美白对虾,并以理化指标、冻结速率和扫描电镜为评价指标,研究不同冻结方式对南美白对虾品质的影响。结果表明:不同冻结方式处理后的南美白对虾冻结速率由快到慢依次为单一浸渍冻结>真空包装联用液体浸渍冻结>单一空气冻结>真空包装联用空气冻结;4种冻结方式处理的南美白对虾酸碱度(pH值)、肌肉组织恢复性及弹性、多酚氧化酶活性(PPO)、盐溶性蛋白含量均低于新鲜的南美白对虾,其中,真空包装联用液体浸渍冻结组的pH、肌肉组织恢复性及弹性、PPO、盐溶性蛋白含量降低最慢;微观扫描电镜观察真空包装联用液体浸渍冻结组对南美白对虾肌肉纤维的损伤最小。真空包装联用浸渍冻结技术更有利于南美白对虾冻结品质的保持。
