Irrigation water became the limiting factor to the persistent improvement of grain production. Based on the data from Gannan County, a semiarid area in the west of Heilongjiang Province, the present situation of the d...Irrigation water became the limiting factor to the persistent improvement of grain production. Based on the data from Gannan County, a semiarid area in the west of Heilongjiang Province, the present situation of the development and utilization of water resources and the suitable water saving irrigation mode were analyzed by using SPA model, which was significant to the efficient and rational utilization of water resources and the improvement of agriculture productivity. The result showed that the model could be applied well to the assessment of development and utilization of water resources and the multi-project optimal selection. Through calculation, it could be found that the utilization of water resources in Gannan County was still in the primary stage, and the integration technology of the optimized water saving irrigation should be combined to support the sustainable development of agriculture in the semiarid area.展开更多
Given the extensive utilization of cantilever retaining walls in construction and development projects,their optimal design and analysis with proper attention to seismic loads is a typical engineering problem.This res...Given the extensive utilization of cantilever retaining walls in construction and development projects,their optimal design and analysis with proper attention to seismic loads is a typical engineering problem.This research presents a new algorithm for pseudo-static analysis of retaining walls employing upper bound method.The algorithm can be utilized to design and check the external and internal stability of the wall based on the proposed mechanism.One of the main features of this algorithm is its ability to determine the critical condition of failure wedges,the minimum safety factor and maximum force acting on the wall,as well as the minimum weight of the wall,simultaneously,by effectively using the multi-objective optimization.The results obtained by the proposed failure mechanisms show that,while using the upper bound limit analysis approach,the active force should be maximized concurrent with optimizing the direction of the plane passing through the back of the heel.The present study also applies the proposed algorithm to determine the critical direction of the earthquake acceleration coefficient.The critical direction of earthquake acceleration coefficient is defined as the direction that maximizes the active force exerted on the wall and minimizes the safety factor for wall stability.The results obtained in this study are in good agreement with those of similar studies carried out based on the limit equilibrium method and finite element analysis.The critical failure mechanisms were determined via optimization with genetic algorithm.展开更多
To obtain the optimal process parameters of stamping forming, finite element analysis and optimization technique were integrated via transforming multi-objective issue into a single-objective issue. A Pareto-based gen...To obtain the optimal process parameters of stamping forming, finite element analysis and optimization technique were integrated via transforming multi-objective issue into a single-objective issue. A Pareto-based genetic algorithm was applied to optimizing the head stamping forming process. In the proposed optimal model, fracture, wrinkle and thickness varying are a function of several factors, such as fillet radius, draw-bead position, blank size and blank-holding force. Hence, it is necessary to investigate the relationship between the objective functions and the variables in order to make objective functions varying minimized simultaneously. Firstly, the central composite experimental(CCD) with four factors and five levels was applied, and the experimental data based on the central composite experimental were acquired. Then, the response surface model(RSM) was set up and the results of the analysis of variance(ANOVA) show that it is reliable to predict the fracture, wrinkle and thickness varying functions by the response surface model. Finally, a Pareto-based genetic algorithm was used to find out a set of Pareto front, which makes fracture, wrinkle and thickness varying minimized integrally. A head stamping case indicates that the present method has higher precision and practicability compared with the "trial and error" procedure.展开更多
Information has two aspects. One aspect is the objective one; another aspect is the subjective one. Shannon has discussed the objective aspect of information in information theory. But the subjective aspect of informa...Information has two aspects. One aspect is the objective one; another aspect is the subjective one. Shannon has discussed the objective aspect of information in information theory. But the subjective aspect of information has not been fully discussed. Someone use “Bayesian approaches” to evaluate the value of information. But in some cases it does not meet the information user＇s need. This paper is focus on the subjective aspect of objectively measurable information and gives formal definitions for information, information utility, and marginal information utility, normalized calculation of information utility. The information discussed in the paper has interdisciplinary nature. This work can be the foundation of many application areas.展开更多
To make the dynamic assembly reliability analysis more effective for complex machinery of multi-object multi-discipline(MOMD),distributed collaborative extremum response surface method(DCERSM)was proposed based on ext...To make the dynamic assembly reliability analysis more effective for complex machinery of multi-object multi-discipline(MOMD),distributed collaborative extremum response surface method(DCERSM)was proposed based on extremum response surface method(ERSM).Firstly,the basic theories of the ERSM and DCERSM were investigated,and the strengths of DCERSM were proved theoretically.Secondly,the mathematical model of the DCERSM was established based upon extremum response surface function(ERSF).Finally,this model was applied to the reliability analysis of blade-tip radial running clearance(BTRRC)of an aeroengine high pressure turbine(HPT)to verify its advantages.The results show that the DCERSM can not only reshape the possibility of the reliability analysis for the complex turbo machinery,but also greatly improve the computational speed,save the computational time and improve the computational efficiency while keeping the accuracy.Thus,the DCERSM is verified to be feasible and effective in the dynamic assembly reliability(DAR)analysis of complex machinery.Moreover,this method offers an useful insight for designing and optimizing the dynamic reliability of complex machinery.展开更多
二氧化碳储能(carbon dioxide energy storage,CES)是一种兼具储能效率高、地理适配性高、安全环保的新型压缩气体储能技术,受到业内广泛关注。该文提出一种耦合聚光式光热利用的超临界二氧化碳储能发电系统(supercritical carbon dioxi...二氧化碳储能(carbon dioxide energy storage,CES)是一种兼具储能效率高、地理适配性高、安全环保的新型压缩气体储能技术,受到业内广泛关注。该文提出一种耦合聚光式光热利用的超临界二氧化碳储能发电系统(supercritical carbon dioxide energy storage-concentrated solar thermal power,SCES-CSTP)和采用分流再压缩、两级回热的改进系统(supercritical carbon dioxide energy storage-concentrated solar thermal power+split compression,SCES-CSTP+SC),探索了光热熔融盐单元与超临界二氧化碳储能的互补优势。研究发现,提高储能压力比和加热温度可以提高储能效率和储能密度,但储能压力比存在最佳值;优化后的SCES-CSTP系统在储能压力比为4.0,加热温度为773.15 K时,储能效率、电-电效率分别为72.37%和432.9%,储能密度为12.94 kW·h/m^(3),(火用)效率为74.4%。SCES-CSTP+SC系统显著增强了回热器传热和系统性能,优选出最佳分流比为0.15和加热温度713.15 K时储能效率最高为75.51%,总(火用)损降低至526.62 kW,(火用)效率提升至77.7%。结果表明,光热对超临界CO_(2)储能系统性能提升具有积极影响。展开更多
基金Supported by Heilongjiang Province Technological and Scientific Research Project(12531051)
文摘Irrigation water became the limiting factor to the persistent improvement of grain production. Based on the data from Gannan County, a semiarid area in the west of Heilongjiang Province, the present situation of the development and utilization of water resources and the suitable water saving irrigation mode were analyzed by using SPA model, which was significant to the efficient and rational utilization of water resources and the improvement of agriculture productivity. The result showed that the model could be applied well to the assessment of development and utilization of water resources and the multi-project optimal selection. Through calculation, it could be found that the utilization of water resources in Gannan County was still in the primary stage, and the integration technology of the optimized water saving irrigation should be combined to support the sustainable development of agriculture in the semiarid area.
文摘Given the extensive utilization of cantilever retaining walls in construction and development projects,their optimal design and analysis with proper attention to seismic loads is a typical engineering problem.This research presents a new algorithm for pseudo-static analysis of retaining walls employing upper bound method.The algorithm can be utilized to design and check the external and internal stability of the wall based on the proposed mechanism.One of the main features of this algorithm is its ability to determine the critical condition of failure wedges,the minimum safety factor and maximum force acting on the wall,as well as the minimum weight of the wall,simultaneously,by effectively using the multi-objective optimization.The results obtained by the proposed failure mechanisms show that,while using the upper bound limit analysis approach,the active force should be maximized concurrent with optimizing the direction of the plane passing through the back of the heel.The present study also applies the proposed algorithm to determine the critical direction of the earthquake acceleration coefficient.The critical direction of earthquake acceleration coefficient is defined as the direction that maximizes the active force exerted on the wall and minimizes the safety factor for wall stability.The results obtained in this study are in good agreement with those of similar studies carried out based on the limit equilibrium method and finite element analysis.The critical failure mechanisms were determined via optimization with genetic algorithm.
基金Project(2012ZX04010-081) supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China
文摘To obtain the optimal process parameters of stamping forming, finite element analysis and optimization technique were integrated via transforming multi-objective issue into a single-objective issue. A Pareto-based genetic algorithm was applied to optimizing the head stamping forming process. In the proposed optimal model, fracture, wrinkle and thickness varying are a function of several factors, such as fillet radius, draw-bead position, blank size and blank-holding force. Hence, it is necessary to investigate the relationship between the objective functions and the variables in order to make objective functions varying minimized simultaneously. Firstly, the central composite experimental(CCD) with four factors and five levels was applied, and the experimental data based on the central composite experimental were acquired. Then, the response surface model(RSM) was set up and the results of the analysis of variance(ANOVA) show that it is reliable to predict the fracture, wrinkle and thickness varying functions by the response surface model. Finally, a Pareto-based genetic algorithm was used to find out a set of Pareto front, which makes fracture, wrinkle and thickness varying minimized integrally. A head stamping case indicates that the present method has higher precision and practicability compared with the "trial and error" procedure.
文摘Information has two aspects. One aspect is the objective one; another aspect is the subjective one. Shannon has discussed the objective aspect of information in information theory. But the subjective aspect of information has not been fully discussed. Someone use “Bayesian approaches” to evaluate the value of information. But in some cases it does not meet the information user＇s need. This paper is focus on the subjective aspect of objectively measurable information and gives formal definitions for information, information utility, and marginal information utility, normalized calculation of information utility. The information discussed in the paper has interdisciplinary nature. This work can be the foundation of many application areas.
基金Project(51175017)supported by the National Natural Science Foundation of ChinaProject(YWF-12-RBYJ-008)supported by the Innovation Foundation of Beihang University for PhD Graduates,ChinaProject(20111102110011)supported by the Research Fund for the Doctoral Program of Higher Education of China
文摘To make the dynamic assembly reliability analysis more effective for complex machinery of multi-object multi-discipline(MOMD),distributed collaborative extremum response surface method(DCERSM)was proposed based on extremum response surface method(ERSM).Firstly,the basic theories of the ERSM and DCERSM were investigated,and the strengths of DCERSM were proved theoretically.Secondly,the mathematical model of the DCERSM was established based upon extremum response surface function(ERSF).Finally,this model was applied to the reliability analysis of blade-tip radial running clearance(BTRRC)of an aeroengine high pressure turbine(HPT)to verify its advantages.The results show that the DCERSM can not only reshape the possibility of the reliability analysis for the complex turbo machinery,but also greatly improve the computational speed,save the computational time and improve the computational efficiency while keeping the accuracy.Thus,the DCERSM is verified to be feasible and effective in the dynamic assembly reliability(DAR)analysis of complex machinery.Moreover,this method offers an useful insight for designing and optimizing the dynamic reliability of complex machinery.
文摘二氧化碳储能(carbon dioxide energy storage,CES)是一种兼具储能效率高、地理适配性高、安全环保的新型压缩气体储能技术,受到业内广泛关注。该文提出一种耦合聚光式光热利用的超临界二氧化碳储能发电系统(supercritical carbon dioxide energy storage-concentrated solar thermal power,SCES-CSTP)和采用分流再压缩、两级回热的改进系统(supercritical carbon dioxide energy storage-concentrated solar thermal power+split compression,SCES-CSTP+SC),探索了光热熔融盐单元与超临界二氧化碳储能的互补优势。研究发现,提高储能压力比和加热温度可以提高储能效率和储能密度,但储能压力比存在最佳值;优化后的SCES-CSTP系统在储能压力比为4.0,加热温度为773.15 K时,储能效率、电-电效率分别为72.37%和432.9%,储能密度为12.94 kW·h/m^(3),(火用)效率为74.4%。SCES-CSTP+SC系统显著增强了回热器传热和系统性能,优选出最佳分流比为0.15和加热温度713.15 K时储能效率最高为75.51%,总(火用)损降低至526.62 kW,(火用)效率提升至77.7%。结果表明,光热对超临界CO_(2)储能系统性能提升具有积极影响。
