乙烯工业不同的裂解装置间存在着设备、技术上的差别,每一种原料在乙烯工厂不同炉型或工艺的裂解装置的乙烯产品收率、能耗也存在着差别。随着新的乙烯工厂的投产,需要同时运行台数众多的差异化裂解装置,从而为通过优化调度乙烯裂解原...乙烯工业不同的裂解装置间存在着设备、技术上的差别,每一种原料在乙烯工厂不同炉型或工艺的裂解装置的乙烯产品收率、能耗也存在着差别。随着新的乙烯工厂的投产,需要同时运行台数众多的差异化裂解装置,从而为通过优化调度乙烯裂解原料实现提高物效、降低能耗提供了空间。对于此类工厂间原料调度及能耗优化问题提出了一种基于P-graph的建模和优化方法 (scheduling generation based on P-graph, SGBP算法),该算法通过P-graph本身提取过程结构信息的能力,在加速求解的同时,保留了次优解集。之后以两个实际的乙烯厂为研究实例,采用提出的SGBP方法实现了原料调度的建模和优化,该方法与MINLP优化算法的对比分析验证了提出方法的优势:(1)可以同时提供较为丰富的最优解与次优解方案;(2)提出方法的最优结果与MINLP的优化效果相当;(3)优化后的整体能耗下降明显,为生产计划人员选择可采用灵活的原料调配方案提供了多种可选择的运行方案。展开更多
Domestic hot water(DHW)systems contribute significantly to the building sector’s energy consumption and carbon emissions,making innovative optimization methods crucial for enhancing DHW energy efficiency.Existing DHW...Domestic hot water(DHW)systems contribute significantly to the building sector’s energy consumption and carbon emissions,making innovative optimization methods crucial for enhancing DHW energy efficiency.Existing DHW system optimizations focus on design parameters and operation modes,but their applicability is limited to specific systems and configurations,overlooking more efficient alternatives.To overcome this problem,combining visualized graphic and algebraic techniques,this study introduces a novel bi-level expanded Process Graph optimization method(BEPGOM)to optimize a DHW system with diverse component-candidates.BEPGOM effectively identifies nontrivial configurations,substantially improving economic and environmental benefits,and enhances solvability with a 98%reduction in solution space.The optimal configuration,consisting of solar heating,PCM tank,and natural gas water heater,reduces the expenditures by 18%and equivalent CO_(2) emission by 34%compared to the existing base case,greatly exceeding the traditional optimization method.Its adaptability,efficiency,and accessibility make BEPGOM a valuable tool in advancing energy system design and promoting carbon neutrality in the building sector.展开更多
Recently, the inverse connected p-median problem on block graphs G(V,E,w) under various cost functions, say rectilinear norm, Chebyshev norm, and bottleneck Hamming distance. Their contributions include finding a nece...Recently, the inverse connected p-median problem on block graphs G(V,E,w) under various cost functions, say rectilinear norm, Chebyshev norm, and bottleneck Hamming distance. Their contributions include finding a necessary and sufficient condition for the connected p-median problem on block graphs, developing algorithms and showing that these problems can be solved in O(n log n) time, where n is the number of vertices in the underlying block graph. Using similar technique, we show that some results are incorrect by a counter-example. Then we redefine some notations, reprove Theorem 1 and redescribe Theorem 2, Theorem 3 and Theorem 4.展开更多
文摘乙烯工业不同的裂解装置间存在着设备、技术上的差别,每一种原料在乙烯工厂不同炉型或工艺的裂解装置的乙烯产品收率、能耗也存在着差别。随着新的乙烯工厂的投产,需要同时运行台数众多的差异化裂解装置,从而为通过优化调度乙烯裂解原料实现提高物效、降低能耗提供了空间。对于此类工厂间原料调度及能耗优化问题提出了一种基于P-graph的建模和优化方法 (scheduling generation based on P-graph, SGBP算法),该算法通过P-graph本身提取过程结构信息的能力,在加速求解的同时,保留了次优解集。之后以两个实际的乙烯厂为研究实例,采用提出的SGBP方法实现了原料调度的建模和优化,该方法与MINLP优化算法的对比分析验证了提出方法的优势:(1)可以同时提供较为丰富的最优解与次优解方案;(2)提出方法的最优结果与MINLP的优化效果相当;(3)优化后的整体能耗下降明显,为生产计划人员选择可采用灵活的原料调配方案提供了多种可选择的运行方案。
基金supported by the Natural Science Foundation of Sichuan Province (No.2022NSFSC0277)the Guangdong Basic and Applied Basic Research Foundation (No.2022A1515011183)the Research Grants Council of Hong Kong (No.CityU 11212620,No.CityU 11215621,No.CityU 11218922).
文摘Domestic hot water(DHW)systems contribute significantly to the building sector’s energy consumption and carbon emissions,making innovative optimization methods crucial for enhancing DHW energy efficiency.Existing DHW system optimizations focus on design parameters and operation modes,but their applicability is limited to specific systems and configurations,overlooking more efficient alternatives.To overcome this problem,combining visualized graphic and algebraic techniques,this study introduces a novel bi-level expanded Process Graph optimization method(BEPGOM)to optimize a DHW system with diverse component-candidates.BEPGOM effectively identifies nontrivial configurations,substantially improving economic and environmental benefits,and enhances solvability with a 98%reduction in solution space.The optimal configuration,consisting of solar heating,PCM tank,and natural gas water heater,reduces the expenditures by 18%and equivalent CO_(2) emission by 34%compared to the existing base case,greatly exceeding the traditional optimization method.Its adaptability,efficiency,and accessibility make BEPGOM a valuable tool in advancing energy system design and promoting carbon neutrality in the building sector.
文摘Recently, the inverse connected p-median problem on block graphs G(V,E,w) under various cost functions, say rectilinear norm, Chebyshev norm, and bottleneck Hamming distance. Their contributions include finding a necessary and sufficient condition for the connected p-median problem on block graphs, developing algorithms and showing that these problems can be solved in O(n log n) time, where n is the number of vertices in the underlying block graph. Using similar technique, we show that some results are incorrect by a counter-example. Then we redefine some notations, reprove Theorem 1 and redescribe Theorem 2, Theorem 3 and Theorem 4.
文摘完全p-支配集是一个著名的NP-难问题,在无线传感网络中被用于构建无线传感节点的自我保护网络.该文主要研究完全p-支配集在DG(Disk Graph)模型及其特殊模型上的参数复杂性及参数算法设计.首先证明完全p-支配集在顶点度受限的UDG(Unit Disk Graph)上仍是NP-难的.为了深入理解完全p-支配集在UDG模型上的难解性根源,利用参数化规约进一步研究了完全p-支配集在UDG上的参数复杂性.基于难解性根源的分析,最后利用树分解技术和动态规划技术,针对平面图(一种特殊DG模型)上的完全p-支配集,设计了一个时间为O((2p+2)19.1·2^(1-k)k3 n+n3)的精确算法,其中n为给定实例中的顶点个数,k为问题解的大小.
