A novel method toward color image segmentation is proposed based on edge linking and region grouping. Firstly,the edges extracted by the Canny detector are linked to form regions.Each of the end points of edges is con...A novel method toward color image segmentation is proposed based on edge linking and region grouping. Firstly,the edges extracted by the Canny detector are linked to form regions.Each of the end points of edges is connected by a direct line to the nearest pixel on another edge segment within a sub-window.A new distance is defined based on the feature that the edge tends to preserve its original direction.By sampling the lines to the image,the image is over-segmented to labeled regions.Secondly,the labeled regions are grouped both locally and globally.A decision tree is constructed to decide the importance of properties that affect the merging procedure.Finally,the result is refined by user’s selection of regions that compose the desired object. Experiments show that the method can effectively segment the object and is much faster than the state-of-the-art color image segmentation methods.展开更多
Segmentation of large AC systems through DC links introduces a new concept that utilizes the advantages of direct current transmission to improve network reliability and increase power transfer capacity. Technical lit...Segmentation of large AC systems through DC links introduces a new concept that utilizes the advantages of direct current transmission to improve network reliability and increase power transfer capacity. Technical literature argues that the segmentation of the AC network and the introduction of DC links at these systems connection points bring benefits to system operation, once contingencies generated on one side of the DC connection point would not be reflected on the other side of DC connection, thereby reducing the likelihood of cascading shutdowns and blackouts due to load restraint on transmission lines and transformers. Amidst this scenario, this paper presents a study of the main topics regarding the use of this new network segmentation philosophy, bringing a practical point of view for the use of this concept at the electrical power system planning. The effect of DC segmentation before a contingency that would initiate major outages in an adapted electrical system model IEEE-14 bus is studied and simulations have been performed with test HVAC systems and segmented by HVDC link. The results have been compared, principally in relation to the voltage bus, reactive power generation, system losses and power flow at the lines, and demonstrated that this new concept improved the grid reliability.展开更多
基金the National Natural Science Foundation of China(No.60704047)the Science and Technology Commission of Shanghai Municipality (No.09410700700)
文摘A novel method toward color image segmentation is proposed based on edge linking and region grouping. Firstly,the edges extracted by the Canny detector are linked to form regions.Each of the end points of edges is connected by a direct line to the nearest pixel on another edge segment within a sub-window.A new distance is defined based on the feature that the edge tends to preserve its original direction.By sampling the lines to the image,the image is over-segmented to labeled regions.Secondly,the labeled regions are grouped both locally and globally.A decision tree is constructed to decide the importance of properties that affect the merging procedure.Finally,the result is refined by user’s selection of regions that compose the desired object. Experiments show that the method can effectively segment the object and is much faster than the state-of-the-art color image segmentation methods.
文摘Segmentation of large AC systems through DC links introduces a new concept that utilizes the advantages of direct current transmission to improve network reliability and increase power transfer capacity. Technical literature argues that the segmentation of the AC network and the introduction of DC links at these systems connection points bring benefits to system operation, once contingencies generated on one side of the DC connection point would not be reflected on the other side of DC connection, thereby reducing the likelihood of cascading shutdowns and blackouts due to load restraint on transmission lines and transformers. Amidst this scenario, this paper presents a study of the main topics regarding the use of this new network segmentation philosophy, bringing a practical point of view for the use of this concept at the electrical power system planning. The effect of DC segmentation before a contingency that would initiate major outages in an adapted electrical system model IEEE-14 bus is studied and simulations have been performed with test HVAC systems and segmented by HVDC link. The results have been compared, principally in relation to the voltage bus, reactive power generation, system losses and power flow at the lines, and demonstrated that this new concept improved the grid reliability.
