Refinery system, a typical example of process systems, is presented as complex network in this paper. The topology of this system is described by task-resource network and modeled as directed and weighted graph, in wh...Refinery system, a typical example of process systems, is presented as complex network in this paper. The topology of this system is described by task-resource network and modeled as directed and weighted graph, in which nodes represent various tasks and edges denote the resources exchanged among tasks. Using the properties of node degree distribution, strength distribution and other weighted quantities, we demonstrate the heterogeneity of the network and point out the relation between structural characters of vertices and the functionality of correspond- ing tasks. The above phenomena indicate that the design requirements and principles of production process contrib- ute to the heterogeneous features of the network. Besides, betweenness centrality of nodes can be used as an impor- tance indicator to provide additional information for decision making. The correlations between structure and weighted properties are investigated to further address the influence brought by production schemes in system con- nectivity patterns. Cascading failures model is employed to analyze the robustness of the network when targeted at- tack happens. Two capacity assignment strategies are compared in order to improve the robustness of the network at certain cost. The refinery system displays more reliable behavior when the protecting strategy considers heteroge- neous properties. This phenomenon further implies the structure-activity relationship of the refinery system and provides insightful suggestions for process system design. The results also indicate that robustness analysis is a _promising applicat!on of methodologies from complex networks to process system engineering..展开更多
This field study sought to determine the all-weather surface construction providing the least contaminated runoff and drainage effluent when exposed to moderate to heavy precipitation and different manure loads in hor...This field study sought to determine the all-weather surface construction providing the least contaminated runoff and drainage effluent when exposed to moderate to heavy precipitation and different manure loads in horse paddocks during wintertime. Two different combinations of non-woven and woven geotextile together with two gravel fractions of 200 nlm were exposed to precipitation and horse manure/urine for two years under two manure regimes （manure removal and manure accumulation）. In a simulated rainfall （SR） study, the test areas were also exposed to 50 mm precipitation for 30 min and 15 kg of horse manure under the two manure regimes. Runoff, drainage effluent and leachate flow were measured and sampled for both regimes. The geotextile-gravel construction reduced runoff and drained the test area throughout the two-year period, confirming construction stability and a dry walking surface area at a mean drain flow of 3.65 L m2 h1. The concentrations of total N, total phosphorus （TP）, chemical oxygen demand （COD） and total solids （TS） in fluids leaving the test areas in winter were lower than in previous studies, due to lower horse density. The mean drainage concentration of TP, COD and TS was 3.4, 231, 739 mg L1, respectively, due to manure removal in the SR study. The TP （1.9 mg L-1） concentration in drain fluids was reduced by 47% in the test area consisting of a single geotextile compared with previously reported values （3.6 mg Ll）. With the paddock designs tested here, non-point pollution from paddocks could be controlled and reduced.展开更多
基金Supported by the National High Technology Research and Development Program of China (2012AA041102)the State Key Development Program for Basic Research of China (2012CB720500)
文摘Refinery system, a typical example of process systems, is presented as complex network in this paper. The topology of this system is described by task-resource network and modeled as directed and weighted graph, in which nodes represent various tasks and edges denote the resources exchanged among tasks. Using the properties of node degree distribution, strength distribution and other weighted quantities, we demonstrate the heterogeneity of the network and point out the relation between structural characters of vertices and the functionality of correspond- ing tasks. The above phenomena indicate that the design requirements and principles of production process contrib- ute to the heterogeneous features of the network. Besides, betweenness centrality of nodes can be used as an impor- tance indicator to provide additional information for decision making. The correlations between structure and weighted properties are investigated to further address the influence brought by production schemes in system con- nectivity patterns. Cascading failures model is employed to analyze the robustness of the network when targeted at- tack happens. Two capacity assignment strategies are compared in order to improve the robustness of the network at certain cost. The refinery system displays more reliable behavior when the protecting strategy considers heteroge- neous properties. This phenomenon further implies the structure-activity relationship of the refinery system and provides insightful suggestions for process system design. The results also indicate that robustness analysis is a _promising applicat!on of methodologies from complex networks to process system engineering..
文摘This field study sought to determine the all-weather surface construction providing the least contaminated runoff and drainage effluent when exposed to moderate to heavy precipitation and different manure loads in horse paddocks during wintertime. Two different combinations of non-woven and woven geotextile together with two gravel fractions of 200 nlm were exposed to precipitation and horse manure/urine for two years under two manure regimes （manure removal and manure accumulation）. In a simulated rainfall （SR） study, the test areas were also exposed to 50 mm precipitation for 30 min and 15 kg of horse manure under the two manure regimes. Runoff, drainage effluent and leachate flow were measured and sampled for both regimes. The geotextile-gravel construction reduced runoff and drained the test area throughout the two-year period, confirming construction stability and a dry walking surface area at a mean drain flow of 3.65 L m2 h1. The concentrations of total N, total phosphorus （TP）, chemical oxygen demand （COD） and total solids （TS） in fluids leaving the test areas in winter were lower than in previous studies, due to lower horse density. The mean drainage concentration of TP, COD and TS was 3.4, 231, 739 mg L1, respectively, due to manure removal in the SR study. The TP （1.9 mg L-1） concentration in drain fluids was reduced by 47% in the test area consisting of a single geotextile compared with previously reported values （3.6 mg Ll）. With the paddock designs tested here, non-point pollution from paddocks could be controlled and reduced.
