This paper presents a topology optimization approach for the surface flows on variable design domains.Via this approach,the matching between the pattern of a surface flow and the 2-manifold used to define the pattern ...This paper presents a topology optimization approach for the surface flows on variable design domains.Via this approach,the matching between the pattern of a surface flow and the 2-manifold used to define the pattern can be optimized,where the 2-manifold is implicitly defined on another fixed 2-manifold named as the base manifold.The fiber bundle topology optimization approach is developed based on the description of the topological structure of the surface flow by using the differential geometry concept of the fiber bundle.The material distribution method is used to achieve the evolution of the pattern of the surface flow.The evolution of the implicit 2-manifold is realized via a homeomorphous map.The design variable of the pattern of the surface flow and that of the implicit 2-manifold are regularized by two sequentially implemented surface-PDE filters.The two surface-PDE filters are coupled,because they are defined on the implicit 2-manifold and base manifold,respectively.The surface Navier-Stokes equations,defined on the implicit 2-manifold,are used to describe the surface flow.The fiber bundle topology optimization problem is analyzed using the continuous adjoint method implemented on the first-order Sobolev space.Several numerical examples have been provided to demonstrate this approach,where the combination of the viscous dissipation and pressure drop is used as the design objective.展开更多
A mathematical model of optimal energy medium distribution in steelmaking process is formulated. In this model, three kinds of important energy mediums including byproduct gases, steam and electricity are considered, ...A mathematical model of optimal energy medium distribution in steelmaking process is formulated. In this model, three kinds of important energy mediums including byproduct gases, steam and electricity are considered, and the objective function accounts for both the change of generation and consumption of the byproduct gases and the demand of low （or middle） pressure steam and electricity for each period to maximize the benefit of products cost and minimize the consumption of energy. The results indicate that the optimal distribution scheme of byproduct gases, middle pressure steam, low pressure steam and electricity is achieved and case study shows that 6% of operation cost is reduced by using the proposed model comparing with the previous model.展开更多
During the loading process,buried gas pipes can experience severe stresses due to soil-structure interaction,the presence of traffic load,the soil’s column weight,daily and/or seasonal temperature changes and uniform...During the loading process,buried gas pipes can experience severe stresses due to soil-structure interaction,the presence of traffic load,the soil’s column weight,daily and/or seasonal temperature changes and uniform internal pressure.In this research,the finite element method is employed to evaluate the behavior of buried Medium Density Polyethylene(MDPE)pipes which have been subjected to damage at the pipe crown.The modeled pipe damage ranges from a very small circular hole to a large circular hole and elliptic holes with various minor to major diameter ratios,a/b,to simulate circular to crack-shaped defects.The computer simulation and stress analyses were performed using the ANSYS software finite element package.The stress distribution around the defect was determined under the aforementioned mechanical and thermal loading conditions.Then,the maximum values of Von Mises stresses in the damaged buried PE pipes,which were evaluated by finite element solution,were compared with their corresponding reduced strength for safe operation with a life expectancy of fifty years.Based on the results,the maximum Von Mises stress values in the defective buried polyethylene gas pipeline are significantly above the pipe strength limit at 35℃.The previously mentioned stress values increase with the following factors:temperature increase,increase in circular hole diameter and decrease in elliptic hole diameter ratio(a/b).The maximum stress in the damaged PE pipe is due to the simultaneous loading effects of soil column weight,internal pressure,vehicle wheel load and pipe temperature increase.Additionally,the novel finite element models and stress plots for the buried damaged pipe and the pipe material allowable strength will be used to investigate the correct repair method for the damaged gas pipeline and to choose the best patch arrangement which will assure a safe repair.展开更多
基金Supported by National Natural Science Foundation of China (Grant No.51875545)Innovation Grant of Changchun Institute of Optics+2 种基金Fine Mechanics and Physics (CIOMP)CAS Project for Young Scientists in Basic Research of China (Grant No.YSBR-066)Science and Technology Development Program of Jilin Province of China (Grant No.SKL202302020)。
文摘This paper presents a topology optimization approach for the surface flows on variable design domains.Via this approach,the matching between the pattern of a surface flow and the 2-manifold used to define the pattern can be optimized,where the 2-manifold is implicitly defined on another fixed 2-manifold named as the base manifold.The fiber bundle topology optimization approach is developed based on the description of the topological structure of the surface flow by using the differential geometry concept of the fiber bundle.The material distribution method is used to achieve the evolution of the pattern of the surface flow.The evolution of the implicit 2-manifold is realized via a homeomorphous map.The design variable of the pattern of the surface flow and that of the implicit 2-manifold are regularized by two sequentially implemented surface-PDE filters.The two surface-PDE filters are coupled,because they are defined on the implicit 2-manifold and base manifold,respectively.The surface Navier-Stokes equations,defined on the implicit 2-manifold,are used to describe the surface flow.The fiber bundle topology optimization problem is analyzed using the continuous adjoint method implemented on the first-order Sobolev space.Several numerical examples have been provided to demonstrate this approach,where the combination of the viscous dissipation and pressure drop is used as the design objective.
基金Item Sponsored by Fundamental Research Funds for Central University of China(N090302010)National High-Tech Researchand Development Program of China(2008AA042901)National Key Science and Technology Support Plan of Ministry of Science and Technology of China(2006BAE03A00)
文摘A mathematical model of optimal energy medium distribution in steelmaking process is formulated. In this model, three kinds of important energy mediums including byproduct gases, steam and electricity are considered, and the objective function accounts for both the change of generation and consumption of the byproduct gases and the demand of low （or middle） pressure steam and electricity for each period to maximize the benefit of products cost and minimize the consumption of energy. The results indicate that the optimal distribution scheme of byproduct gases, middle pressure steam, low pressure steam and electricity is achieved and case study shows that 6% of operation cost is reduced by using the proposed model comparing with the previous model.
文摘During the loading process,buried gas pipes can experience severe stresses due to soil-structure interaction,the presence of traffic load,the soil’s column weight,daily and/or seasonal temperature changes and uniform internal pressure.In this research,the finite element method is employed to evaluate the behavior of buried Medium Density Polyethylene(MDPE)pipes which have been subjected to damage at the pipe crown.The modeled pipe damage ranges from a very small circular hole to a large circular hole and elliptic holes with various minor to major diameter ratios,a/b,to simulate circular to crack-shaped defects.The computer simulation and stress analyses were performed using the ANSYS software finite element package.The stress distribution around the defect was determined under the aforementioned mechanical and thermal loading conditions.Then,the maximum values of Von Mises stresses in the damaged buried PE pipes,which were evaluated by finite element solution,were compared with their corresponding reduced strength for safe operation with a life expectancy of fifty years.Based on the results,the maximum Von Mises stress values in the defective buried polyethylene gas pipeline are significantly above the pipe strength limit at 35℃.The previously mentioned stress values increase with the following factors:temperature increase,increase in circular hole diameter and decrease in elliptic hole diameter ratio(a/b).The maximum stress in the damaged PE pipe is due to the simultaneous loading effects of soil column weight,internal pressure,vehicle wheel load and pipe temperature increase.Additionally,the novel finite element models and stress plots for the buried damaged pipe and the pipe material allowable strength will be used to investigate the correct repair method for the damaged gas pipeline and to choose the best patch arrangement which will assure a safe repair.
