The Beijing-Tianjin-Hebei Plain(BTHP)is the political,economic and cultural center of China,where groundwater is the main source of water supply to support social and economic development.Continuous overdraft of the r...The Beijing-Tianjin-Hebei Plain(BTHP)is the political,economic and cultural center of China,where groundwater is the main source of water supply to support social and economic development.Continuous overdraft of the resources has caused a persistent decline of groundwater level and formed a huge cone of depression at a regional scale.This paper addresses current groundwater situation over the BTHP area.The paper also delineates the groundwater flow field,using groundwater level data,in order to provide an effective method for the restoration of groundwater level and associated water resources management.Based on the analysis of multiple factors,such as groundwater level,soil salinization,ground subsidence,groundwater recharge and storage,urban underground space security,formation of fractures,and seawater intrusion,the threshold for groundwater level restoration is defined,and some measures for groundwater over-exploitation management are accordingly proposed.The study shows that:(i)Since the 1980s to 2020,shallow groundwater level in the western part of the BTHP area has dropped by 25 m to 60m,while the cumulative decline of deep groundwater in the central and eastern regions is in the range of 40–80 m;(ii)The water table of the shallow groundwater within the depression zone over the Western Piedmont Plain should be controlled in the range of 15–30 m below ground level(mbgl),while the depth of groundwater level in large and medium-sized urban areas should be controlled within 20–30 mbgl.The groundwater level in the resource preservation area should be controlled within 10–15 mbgl,and the groundwater level in the area with identified soil salinization in the central and eastern plain should be controlled within 3–10 mbgl.However,for the deep groundwater in the central and eastern plainwater,the main focus of the resources management is to control the land subsidence.The water level in the severe land subsidence area should be controlled within 45–60 mbgl,and in the general subsidence area should be controlled within 30–45 mbgl;(iii)Based on the water level recovery threshold and proposed groundwater overdraft management program,if the balance of abstraction and recharge is reached in 2025,the shallow groundwater abstraction needs to be gradually reduced by about 2×10^(8) m^(3).Meanwhile,the ecological water replenishment of rivers through the South-to-North Water Transfer Project should be increased to 28.58×10^(8) m^(3)/a,and the deep groundwater abstraction needs to be gradually reduced by 2.24×10^(8) m^(3).To reach the target of shallow groundwater level in 2040,surface water replacement is recommended with a rate of 25.77×10^(8) m^(3)/a and the ecological water replenishment of rivers in the South-to-North Water Diversion Project should reach 33.51×10^(8) m^(3)/a.For deep groundwater recovery,it is recommended to replace the deep freshwater extraction with the utilization of shallow salt water by 2.82×10^(8) m^(3),in addition to the amount of 7.86×10^(8) m^(3) by water diversion.The results are of great significance to the remediation of groundwater over-exploitation,the regulation of water resources development and utilization,and ecological protection in Beijing-Tianjin-Hebei plain.展开更多
Accurate segmentation is an important and challenging task in any computer vision system. It also plays a vital role in computerized analysis of skin lesion images. This paper presents a new segmentation method that c...Accurate segmentation is an important and challenging task in any computer vision system. It also plays a vital role in computerized analysis of skin lesion images. This paper presents a new segmentation method that combines the advan-tages of fuzzy C mean algorithm, thresholding and level set method. 3-class Fuzzy C mean thresholding is applied to initialize level set automatically and also for estimating controlling parameters for level set evolution. Parameters for performance evaluation are presented and segmentation results are compared with some other state-of-the-art segmentation methods. Increased true detection rate and reduced false positive and false negative errors confirm the effectiveness of proposed method for skin cancer detection.展开更多
A novel flotation froth image segmentation based on threshold level set method is put forward in view of the problem of over-segmentation and under-segmentation which occurs when the existing method segmented the flot...A novel flotation froth image segmentation based on threshold level set method is put forward in view of the problem of over-segmentation and under-segmentation which occurs when the existing method segmented the flotation froth images. Firstly, the proposed method adopts histogram equalization to improve the contrast of the image, and then chooses the upper threshold and lower threshold from grey value of histogram of the image equalization, and complete image segmentation using the level set method. In this paper, the model which integrates edge with region level set model is utilized, and the speed energy term is introduced to segment the target. Experimental results show that the proposed method has better segmentation results and higher segmentation efficiency on the images with under-segmentation and incorrect segmentation, and it is meaningful for ore dressing industrial.展开更多
基金funded by Geological survey project of China Geological Survey (DD20190336, DD20221752)。
文摘The Beijing-Tianjin-Hebei Plain(BTHP)is the political,economic and cultural center of China,where groundwater is the main source of water supply to support social and economic development.Continuous overdraft of the resources has caused a persistent decline of groundwater level and formed a huge cone of depression at a regional scale.This paper addresses current groundwater situation over the BTHP area.The paper also delineates the groundwater flow field,using groundwater level data,in order to provide an effective method for the restoration of groundwater level and associated water resources management.Based on the analysis of multiple factors,such as groundwater level,soil salinization,ground subsidence,groundwater recharge and storage,urban underground space security,formation of fractures,and seawater intrusion,the threshold for groundwater level restoration is defined,and some measures for groundwater over-exploitation management are accordingly proposed.The study shows that:(i)Since the 1980s to 2020,shallow groundwater level in the western part of the BTHP area has dropped by 25 m to 60m,while the cumulative decline of deep groundwater in the central and eastern regions is in the range of 40–80 m;(ii)The water table of the shallow groundwater within the depression zone over the Western Piedmont Plain should be controlled in the range of 15–30 m below ground level(mbgl),while the depth of groundwater level in large and medium-sized urban areas should be controlled within 20–30 mbgl.The groundwater level in the resource preservation area should be controlled within 10–15 mbgl,and the groundwater level in the area with identified soil salinization in the central and eastern plain should be controlled within 3–10 mbgl.However,for the deep groundwater in the central and eastern plainwater,the main focus of the resources management is to control the land subsidence.The water level in the severe land subsidence area should be controlled within 45–60 mbgl,and in the general subsidence area should be controlled within 30–45 mbgl;(iii)Based on the water level recovery threshold and proposed groundwater overdraft management program,if the balance of abstraction and recharge is reached in 2025,the shallow groundwater abstraction needs to be gradually reduced by about 2×10^(8) m^(3).Meanwhile,the ecological water replenishment of rivers through the South-to-North Water Transfer Project should be increased to 28.58×10^(8) m^(3)/a,and the deep groundwater abstraction needs to be gradually reduced by 2.24×10^(8) m^(3).To reach the target of shallow groundwater level in 2040,surface water replacement is recommended with a rate of 25.77×10^(8) m^(3)/a and the ecological water replenishment of rivers in the South-to-North Water Diversion Project should reach 33.51×10^(8) m^(3)/a.For deep groundwater recovery,it is recommended to replace the deep freshwater extraction with the utilization of shallow salt water by 2.82×10^(8) m^(3),in addition to the amount of 7.86×10^(8) m^(3) by water diversion.The results are of great significance to the remediation of groundwater over-exploitation,the regulation of water resources development and utilization,and ecological protection in Beijing-Tianjin-Hebei plain.
文摘Accurate segmentation is an important and challenging task in any computer vision system. It also plays a vital role in computerized analysis of skin lesion images. This paper presents a new segmentation method that combines the advan-tages of fuzzy C mean algorithm, thresholding and level set method. 3-class Fuzzy C mean thresholding is applied to initialize level set automatically and also for estimating controlling parameters for level set evolution. Parameters for performance evaluation are presented and segmentation results are compared with some other state-of-the-art segmentation methods. Increased true detection rate and reduced false positive and false negative errors confirm the effectiveness of proposed method for skin cancer detection.
文摘A novel flotation froth image segmentation based on threshold level set method is put forward in view of the problem of over-segmentation and under-segmentation which occurs when the existing method segmented the flotation froth images. Firstly, the proposed method adopts histogram equalization to improve the contrast of the image, and then chooses the upper threshold and lower threshold from grey value of histogram of the image equalization, and complete image segmentation using the level set method. In this paper, the model which integrates edge with region level set model is utilized, and the speed energy term is introduced to segment the target. Experimental results show that the proposed method has better segmentation results and higher segmentation efficiency on the images with under-segmentation and incorrect segmentation, and it is meaningful for ore dressing industrial.
