The current popular methods for decision making and project optimisation in mine ventilation contain a number of deficiencies as they are solely based on either subjective knowledge or objective information.This paper...The current popular methods for decision making and project optimisation in mine ventilation contain a number of deficiencies as they are solely based on either subjective knowledge or objective information.This paper presents a new approach to rank the alternatives by G1-coefficient of variation method.The focus of this approach is the use of the combination weighing,which is able to compensate for the deficiencies in the method of evaluation index single weighing.In the case study,an appropriate evaluation index system was established to determine the evaluation value of each ventilation mode.Then the proposed approach was used to select the best development face ventilation mode.The result shows that the proposed approach is able to rank the alternative development face ventilation mode reasonably,the combination weighing method had the advantages of both subjective and objective weighing methods in that it took into consideration of both the experience and wisdom of experts,and the new changes in objective conditions.This approach provides a more reasonable and reliable procedure to analyse and evaluate different ventilation modes.展开更多
It is not reasonable that one can only use the adjoint of model in data assimilation. The simulated numerical experiment shows that for the tidal model, the result of the adjoint of equation is almost the same as that...It is not reasonable that one can only use the adjoint of model in data assimilation. The simulated numerical experiment shows that for the tidal model, the result of the adjoint of equation is almost the same as that of the adjoint of model: the averaged absolute difference of the amplitude between observations and simulation is less than 5.0 cm and that of the phase-lag is less than 5.0°. The results are both in good agreement with the observed M2 tide in the Bohai Sea and the Yellow Sea. For comparison, the traditional methods also have been used to simulate M2 tide in the Bohai Sea and the Yellow Sea. The initial guess values of the boundary conditions are given first, and then are adjusted to acquire the simulated results that are as close as possible to the observations. As the boundary conditions contain 72 values, which should be adjusted and how to adjust them can only be partially solved by adjusting them many times. The satisfied results are hard to acquire even gigantic efforts are done. Here, the automation of the treatment of the open boundary conditions is realized. The method is unique and superior to the traditional methods. It is emphasized that if the adjoint of equation is used, tedious and complicated mathematical deduction can be avoided. Therefore the adjoint of equation should attract much attention.展开更多
Short-term traffic flow forecasting is a significant part of intelligent transportation system.In some traffic control scenarios,obtaining future traffic flow in advance is conducive to highway management department t...Short-term traffic flow forecasting is a significant part of intelligent transportation system.In some traffic control scenarios,obtaining future traffic flow in advance is conducive to highway management department to have sufficient time to formulate corresponding traffic flow control measures.In hence,it is meaningful to establish an accurate short-term traffic flow method and provide reference for peak traffic flow warning.This paper proposed a new hybrid model for traffic flow forecasting,which is composed of the variational mode decomposition(VMD)method,the group method of data handling(GMDH)neural network,bi-directional long and short term memory(BILSTM)network and ELMAN network,and is optimized by the imperialist competitive algorithm(ICA)method.To illustrate the performance of the proposed model,there are several comparative experiments between the proposed model and other models.The experiment results show that 1)BILSTM network,GMDH network and ELMAN network have better predictive performance than other single models;2)VMD can significantly improve the predictive performance of the ICA-GMDH-BILSTM-ELMAN model.The effect of VMD method is better than that of EEMD method and FEEMD method.To conclude,the proposed model which is made up of the VMD method,the ICA method,the BILSTM network,the GMDH network and the ELMAN network has excellent predictive ability for traffic flow series.展开更多
A finite element algorithm combined with divergence condition was presented for computing three-dimensional(3D) magnetotelluric forward modeling. The finite element equation of three-dimensional magnetotelluric forwar...A finite element algorithm combined with divergence condition was presented for computing three-dimensional(3D) magnetotelluric forward modeling. The finite element equation of three-dimensional magnetotelluric forward modeling was derived from Maxwell's equations using general variation principle. The divergence condition was added forcedly to the electric field boundary value problem, which made the solution correct. The system of equation of the finite element algorithm was a large sparse, banded, symmetric, ill-conditioned, non-Hermitian complex matrix equation, which can be solved using the Bi-CGSTAB method. In order to prove correctness of the three-dimensional magnetotelluric forward algorithm, the computed results and analytic results of one-dimensional geo-electrical model were compared. In addition, the three-dimensional magnetotelluric forward algorithm is given a further evaluation by computing COMMEMI model. The forward modeling results show that the algorithm is very efficient, and it has a lot of advantages, such as the high precision, the canonical process of solving problem, meeting the internal boundary condition automatically and adapting to all kinds of distribution of multi-substances.展开更多
【目的】深度剖析近年来我国油菜碳足迹的时空演变及来源构成变化趋势,并提出油菜种植减排增产的可行方向,为制定油菜种植产业政策和优化种植结构提供参考依据。【方法】基于油菜投入产出数据,采用生命周期评价法测算2004—2022年我国1...【目的】深度剖析近年来我国油菜碳足迹的时空演变及来源构成变化趋势,并提出油菜种植减排增产的可行方向,为制定油菜种植产业政策和优化种植结构提供参考依据。【方法】基于油菜投入产出数据,采用生命周期评价法测算2004—2022年我国15个油菜种植省份的油菜碳足迹,分析油菜碳足迹变化特征,并有针对性提出减排策略。【结果】2004—2022年我国油菜温室气体排放总量、单位面积碳足迹和单位产量碳足迹总体上呈增长趋势,温室气体排放总量年均增长量约0.34×10^(9)kg CO_(2)eq,单位产量碳足迹年均增长量约0.01 kg CO_(2)eq/kg,单位面积碳足迹年均增长量约0.049×10^(3)kg CO_(2)eq/ha;在省份层面,长江中上游及西南、西北种植区的油菜温室气体排放总量呈正增长趋势,以湖南省增长最快,年均增长量为20.668×10^(7)kg CO_(2)eq,而江苏省、安徽省、河南省和浙江省呈下降趋势,对应的年均变化量分别为-9.925×10^(7)、-8.606×10^(7)、-2.869×10^(7)和-2.324×10^(7)kg CO_(2)eq。除重庆市外,我国主要油菜种植区的单位面积碳足迹均随时间的推移而增长,其中增长较快的有湖南省、贵州省和甘肃省,年均增长量分别为98.632、103.165和120.070 kg CO_(2)eq/ha。我国大部分油菜种植区的单位产量碳足迹随时间的推移而增加,仅重庆市、江苏省、云南省、浙江省、江西省和四川省的单位产量碳足迹呈降低趋势。从碳足迹构成来看,化肥生产和化肥施用是我国油菜种植中碳足迹的主要来源,二者的单位面积碳足迹占比合计为70.94%,其次是灌溉和人工产生的碳排放,即控制化肥和灌溉投入量是我国油菜种植减排的主要方向。我国各省油菜种植各环节单位面积碳足迹占比存在一定差异,但总体上与全国油菜单位面积碳足迹构成保持一致。【建议】积极推广油菜化肥减量增效技术,提高化肥利用效率;普及推广油菜节水节能灌溉技术,着力减少灌溉能耗;科学规划油菜产业短长期目标,优化生产区域布局。展开更多
基金Projects(51504286,51374242)supported by the National Natural Science Foundation of ChinaProject(2015M572270)supported by China Postdoctoral Science FoundationProject(2015RS4004)supported by the Science and Technology Plan of Hunan Province,China
文摘The current popular methods for decision making and project optimisation in mine ventilation contain a number of deficiencies as they are solely based on either subjective knowledge or objective information.This paper presents a new approach to rank the alternatives by G1-coefficient of variation method.The focus of this approach is the use of the combination weighing,which is able to compensate for the deficiencies in the method of evaluation index single weighing.In the case study,an appropriate evaluation index system was established to determine the evaluation value of each ventilation mode.Then the proposed approach was used to select the best development face ventilation mode.The result shows that the proposed approach is able to rank the alternative development face ventilation mode reasonably,the combination weighing method had the advantages of both subjective and objective weighing methods in that it took into consideration of both the experience and wisdom of experts,and the new changes in objective conditions.This approach provides a more reasonable and reliable procedure to analyse and evaluate different ventilation modes.
文摘It is not reasonable that one can only use the adjoint of model in data assimilation. The simulated numerical experiment shows that for the tidal model, the result of the adjoint of equation is almost the same as that of the adjoint of model: the averaged absolute difference of the amplitude between observations and simulation is less than 5.0 cm and that of the phase-lag is less than 5.0°. The results are both in good agreement with the observed M2 tide in the Bohai Sea and the Yellow Sea. For comparison, the traditional methods also have been used to simulate M2 tide in the Bohai Sea and the Yellow Sea. The initial guess values of the boundary conditions are given first, and then are adjusted to acquire the simulated results that are as close as possible to the observations. As the boundary conditions contain 72 values, which should be adjusted and how to adjust them can only be partially solved by adjusting them many times. The satisfied results are hard to acquire even gigantic efforts are done. Here, the automation of the treatment of the open boundary conditions is realized. The method is unique and superior to the traditional methods. It is emphasized that if the adjoint of equation is used, tedious and complicated mathematical deduction can be avoided. Therefore the adjoint of equation should attract much attention.
基金Project(61873283)supported by the National Natural Science Foundation of ChinaProject(KQ1707017)supported by the Changsha Science&Technology Project,ChinaProject(2019CX005)supported by the Innovation Driven Project of the Central South University,China。
文摘Short-term traffic flow forecasting is a significant part of intelligent transportation system.In some traffic control scenarios,obtaining future traffic flow in advance is conducive to highway management department to have sufficient time to formulate corresponding traffic flow control measures.In hence,it is meaningful to establish an accurate short-term traffic flow method and provide reference for peak traffic flow warning.This paper proposed a new hybrid model for traffic flow forecasting,which is composed of the variational mode decomposition(VMD)method,the group method of data handling(GMDH)neural network,bi-directional long and short term memory(BILSTM)network and ELMAN network,and is optimized by the imperialist competitive algorithm(ICA)method.To illustrate the performance of the proposed model,there are several comparative experiments between the proposed model and other models.The experiment results show that 1)BILSTM network,GMDH network and ELMAN network have better predictive performance than other single models;2)VMD can significantly improve the predictive performance of the ICA-GMDH-BILSTM-ELMAN model.The effect of VMD method is better than that of EEMD method and FEEMD method.To conclude,the proposed model which is made up of the VMD method,the ICA method,the BILSTM network,the GMDH network and the ELMAN network has excellent predictive ability for traffic flow series.
基金Project(60672042) supported by the National Natural Science Foundation of China
文摘A finite element algorithm combined with divergence condition was presented for computing three-dimensional(3D) magnetotelluric forward modeling. The finite element equation of three-dimensional magnetotelluric forward modeling was derived from Maxwell's equations using general variation principle. The divergence condition was added forcedly to the electric field boundary value problem, which made the solution correct. The system of equation of the finite element algorithm was a large sparse, banded, symmetric, ill-conditioned, non-Hermitian complex matrix equation, which can be solved using the Bi-CGSTAB method. In order to prove correctness of the three-dimensional magnetotelluric forward algorithm, the computed results and analytic results of one-dimensional geo-electrical model were compared. In addition, the three-dimensional magnetotelluric forward algorithm is given a further evaluation by computing COMMEMI model. The forward modeling results show that the algorithm is very efficient, and it has a lot of advantages, such as the high precision, the canonical process of solving problem, meeting the internal boundary condition automatically and adapting to all kinds of distribution of multi-substances.
文摘【目的】深度剖析近年来我国油菜碳足迹的时空演变及来源构成变化趋势,并提出油菜种植减排增产的可行方向,为制定油菜种植产业政策和优化种植结构提供参考依据。【方法】基于油菜投入产出数据,采用生命周期评价法测算2004—2022年我国15个油菜种植省份的油菜碳足迹,分析油菜碳足迹变化特征,并有针对性提出减排策略。【结果】2004—2022年我国油菜温室气体排放总量、单位面积碳足迹和单位产量碳足迹总体上呈增长趋势,温室气体排放总量年均增长量约0.34×10^(9)kg CO_(2)eq,单位产量碳足迹年均增长量约0.01 kg CO_(2)eq/kg,单位面积碳足迹年均增长量约0.049×10^(3)kg CO_(2)eq/ha;在省份层面,长江中上游及西南、西北种植区的油菜温室气体排放总量呈正增长趋势,以湖南省增长最快,年均增长量为20.668×10^(7)kg CO_(2)eq,而江苏省、安徽省、河南省和浙江省呈下降趋势,对应的年均变化量分别为-9.925×10^(7)、-8.606×10^(7)、-2.869×10^(7)和-2.324×10^(7)kg CO_(2)eq。除重庆市外,我国主要油菜种植区的单位面积碳足迹均随时间的推移而增长,其中增长较快的有湖南省、贵州省和甘肃省,年均增长量分别为98.632、103.165和120.070 kg CO_(2)eq/ha。我国大部分油菜种植区的单位产量碳足迹随时间的推移而增加,仅重庆市、江苏省、云南省、浙江省、江西省和四川省的单位产量碳足迹呈降低趋势。从碳足迹构成来看,化肥生产和化肥施用是我国油菜种植中碳足迹的主要来源,二者的单位面积碳足迹占比合计为70.94%,其次是灌溉和人工产生的碳排放,即控制化肥和灌溉投入量是我国油菜种植减排的主要方向。我国各省油菜种植各环节单位面积碳足迹占比存在一定差异,但总体上与全国油菜单位面积碳足迹构成保持一致。【建议】积极推广油菜化肥减量增效技术,提高化肥利用效率;普及推广油菜节水节能灌溉技术,着力减少灌溉能耗;科学规划油菜产业短长期目标,优化生产区域布局。
