The finite element(FE)-based simulation of welding characteristics was carried out to explore the relationship among welding assembly properties for the parallel T-shaped thin-walled parts of an antenna structure.The ...The finite element(FE)-based simulation of welding characteristics was carried out to explore the relationship among welding assembly properties for the parallel T-shaped thin-walled parts of an antenna structure.The effects of welding direction,clamping,fixture release time,fixed constraints,and welding sequences on these properties were analyzed,and the mapping relationship among welding characteristics was thoroughly examined.Different machine learning algorithms,including the generalized regression neural network(GRNN),wavelet neural network(WNN),and fuzzy neural network(FNN),are used to predict the multiple welding properties of thin-walled parts to mirror their variation trend and verify the correctness of the mapping relationship.Compared with those from GRNN and WNN,the maximum mean relative errors for the predicted values of deformation,temperature,and residual stress with FNN were less than 4.8%,1.4%,and 4.4%,respectively.These results indicate that FNN generated the best predicted welding characteristics.Analysis under various welding conditions also shows a mapping relationship among welding deformation,temperature,and residual stress over a period of time.This finding further provides a paramount basis for the control of welding assembly errors of an antenna structure in the future.展开更多
In order to accelerate the research on the property optimization of titanium alloy based on high-throughput methods,it is necessary to reveal the relationship between hardness and other mechanical properties which is ...In order to accelerate the research on the property optimization of titanium alloy based on high-throughput methods,it is necessary to reveal the relationship between hardness and other mechanical properties which is still unclear.In this work,taking Ti20C alloy as research object,almost all the microstructure of dual-phase titanium alloys were covered by traversing over 100 heat treatment schemes.Then,massive experiments including microstructure characterization and performance test were conducted,obtaining 51,590 pieces of microstructure data and 3591 pieces of mechanical property data.Subsequently,based on large-scale data-driven technology,the quantitative mapping relationship between hardness and other mechanical properties was deeply discussed.The results of random forest models showed that the correlation between hardness(H)and Charpy impact energy(A_(k))(or elongation,A)was hardly dependent on the microstructure types,while the relationship between H and tensile strength(R_(m))(or yield strength,R_(p0.2))was highly dependent on microstructure types.Specifically,combined with statistical analysis,it was found that the relationship between H and Ak(or A)were negatively linear.Interestingly,the relationship between H and strength was positively linear for equiaxed microstructure,and strength was linked to d^(−1/2)(d,equivalent circle diameter)ofα-grains in the form of classical Hall–Petch formula;but for other microstructures,the relationships were quadratic.Furthermore,the above rules were nearly the same in the rolling direction and transverse direction.Finally,a"four-quadrant partition map"between H and R_(p0.2)/R_(m) was established as a versatile material-screening tool,which can provide guidance for on-demand selection of titanium alloys.展开更多
Conventional soil maps contain valuable knowledge on soil–environment relationships.Such knowledge can be extracted for use when updating conventional soil maps with improved environmental data.Existing methods take ...Conventional soil maps contain valuable knowledge on soil–environment relationships.Such knowledge can be extracted for use when updating conventional soil maps with improved environmental data.Existing methods take all polygons of the same map unit on a map as a whole to extract the soil–environment relationship.Such approach ignores the difference in the environmental conditions represented by individual soil polygons of the same map unit.This paper proposes a method of mining soil–environment relationships from individual soil polygons to update conventional soil maps.The proposed method consists of three major steps.Firstly,the soil–environment relationships represented by each individual polygon on a conventional soil map are extracted in the form of frequency distribution curves for the involved environmental covariates.Secondly,for each environmental covariate,these frequency distribution curves from individual polygons of the same soil map unit are synthesized to form the overall soil–environment relationship for that soil map unit across the mapped area.And lastly,the extracted soil–environment relationships are applied to updating the conventional soil map with new,improved environmental data by adopting a soil land inference model(SoLIM)framework.This study applied the proposed method to updating a conventional soil map of the Raffelson watershed in La Crosse County,Wisconsin,United States.The result from the proposed method was compared with that from the previous method of taking all polygons within the same soil map unit on a map as a whole.Evaluation results with independent soil samples showed that the proposed method exhibited better performance and produced higher accuracy.展开更多
This paper takes the basic mathematical operations required to manipulate the cognitive maps. This paper start by presenting all the values that a causal relationship can take. By the using of causal algebra, cognitiv...This paper takes the basic mathematical operations required to manipulate the cognitive maps. This paper start by presenting all the values that a causal relationship can take. By the using of causal algebra, cognitive map (CC) become not only a graphical representation of a person’s beliefs, an agent or a particular area but also can capture the causal relationships existing between the concepts of a given system in a simple manner. Cognitive maps do not use a conventional algebra;algebra causal is needed to treat.展开更多
In this study, non radioactive Digoxigenin labeled ribosomal DNA(rDNA) probes were used for Southern blotting analysis to study the molecular phylogeny of the giant panda and related species. Restriction maps in the ...In this study, non radioactive Digoxigenin labeled ribosomal DNA(rDNA) probes were used for Southern blotting analysis to study the molecular phylogeny of the giant panda and related species. Restriction maps in the regions of rDNA spacers were compared between giant panda( Ailuropoda melanoleuca ), lesser panda( Ailurus fulgens ), Asiatic black bear( Selenarctos thibetanus ), sun bear( Helarctos malayanus ), raccoon( Procyon lotor ) and lynx( Felis lynx ). Phylogenetic trees for these species were constructed using maximum likelihood and parsimony method. The results show that in respect to rDNA RFLPs, the giant panda is more closely related to bear than to lesser panda; while the lesser panda is slightly related to the raccoon.展开更多
To develop a fundamental understanding of the flow behavior and optimal hot workability parameters of this material, the hot workability and deformation mechanisms of the as-cast 21Cr EDSS were studied using processin...To develop a fundamental understanding of the flow behavior and optimal hot workability parameters of this material, the hot workability and deformation mechanisms of the as-cast 21Cr EDSS were studied using processing map technology combined with microstructure analysis and isothermal hot compression over the temperature range of 1000-1150 ℃ and strain rate range of 0.01-10 s-1. The processing maps and constitutive equation of peak stress were developed based on Prasad＇s and Murty＇s criteria. The results show that the processing maps exhibit a stable domain at 1000-1150 ℃ and 0.01-1 s-1. The instability domain is exhibited at high strain rates （≥1 s-l）. This implies that Murty＇s criterion can predict the unstable domain with high reliability. The detailed deformation mechanisms are also studied by microstructure observation, showing that the flow localization and microcracking are responsible for the flow instability.展开更多
In order to determine the safe region of 42CrMo4 steel during hot working and obtain excellent workability,the hot deformation behavior at the temperatures of 850-1150℃and the strain rates of 0.01-10 s^(-1)was invest...In order to determine the safe region of 42CrMo4 steel during hot working and obtain excellent workability,the hot deformation behavior at the temperatures of 850-1150℃and the strain rates of 0.01-10 s^(-1)was investigated through single-pass compression test of thermo-simulation.Through observing and analyzing the true stress-strain curves,the conclusion may be drawn that the flow stress value increases with the decrease in deformation temperature and the increase in strain rate.Raising temperature and reducing strain rate are conductive to dynamic recrystallization(DRX)nucleating and growing,but adiabatic heating caused by higher strain rate can also promote it.Since the Zener-Hollomon(Z)value and dynamic recrystallized grain size(D_(DRX))have completely opposite trends with deformation condition parameters,the expression of Z value and DDRX can be determined as:D_(DRx)=15,567.645Z^(-02174).The processing map and instability map constructed at a strain of 0.9 show that the suitable window for hot working with a true strain of 0.9 is in the temperature range of 970-1150℃and strain rate range of 0.01-0.25 s^(-1),as well as at the temperature of 1150℃ and strain rate range of 0.25-10 s^(-1).The instability phenomenon appears in the process interval of 850-1096℃ and 0.22-10 s^(-1).展开更多
基金The Natural Science Foundation of Jiangsu Province,China(No.BK20200470)China Postdoctoral Science Foundation(No.2021M691595)Innovation and Entrepreneurship Plan Talent Program of Jiangsu Province(No.AD99002).
文摘The finite element(FE)-based simulation of welding characteristics was carried out to explore the relationship among welding assembly properties for the parallel T-shaped thin-walled parts of an antenna structure.The effects of welding direction,clamping,fixture release time,fixed constraints,and welding sequences on these properties were analyzed,and the mapping relationship among welding characteristics was thoroughly examined.Different machine learning algorithms,including the generalized regression neural network(GRNN),wavelet neural network(WNN),and fuzzy neural network(FNN),are used to predict the multiple welding properties of thin-walled parts to mirror their variation trend and verify the correctness of the mapping relationship.Compared with those from GRNN and WNN,the maximum mean relative errors for the predicted values of deformation,temperature,and residual stress with FNN were less than 4.8%,1.4%,and 4.4%,respectively.These results indicate that FNN generated the best predicted welding characteristics.Analysis under various welding conditions also shows a mapping relationship among welding deformation,temperature,and residual stress over a period of time.This finding further provides a paramount basis for the control of welding assembly errors of an antenna structure in the future.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.51901102 and 52101005).
文摘In order to accelerate the research on the property optimization of titanium alloy based on high-throughput methods,it is necessary to reveal the relationship between hardness and other mechanical properties which is still unclear.In this work,taking Ti20C alloy as research object,almost all the microstructure of dual-phase titanium alloys were covered by traversing over 100 heat treatment schemes.Then,massive experiments including microstructure characterization and performance test were conducted,obtaining 51,590 pieces of microstructure data and 3591 pieces of mechanical property data.Subsequently,based on large-scale data-driven technology,the quantitative mapping relationship between hardness and other mechanical properties was deeply discussed.The results of random forest models showed that the correlation between hardness(H)and Charpy impact energy(A_(k))(or elongation,A)was hardly dependent on the microstructure types,while the relationship between H and tensile strength(R_(m))(or yield strength,R_(p0.2))was highly dependent on microstructure types.Specifically,combined with statistical analysis,it was found that the relationship between H and Ak(or A)were negatively linear.Interestingly,the relationship between H and strength was positively linear for equiaxed microstructure,and strength was linked to d^(−1/2)(d,equivalent circle diameter)ofα-grains in the form of classical Hall–Petch formula;but for other microstructures,the relationships were quadratic.Furthermore,the above rules were nearly the same in the rolling direction and transverse direction.Finally,a"four-quadrant partition map"between H and R_(p0.2)/R_(m) was established as a versatile material-screening tool,which can provide guidance for on-demand selection of titanium alloys.
基金supported by the National Natural Science Foundation of China (41431177 and 41422109)the Innovation Project of State Key Laboratory of Resources and Environmental Information System of China (O88RA20CYA)the Outstanding Innovation Team in Colleges and Universities in Jiangsu Province, China
文摘Conventional soil maps contain valuable knowledge on soil–environment relationships.Such knowledge can be extracted for use when updating conventional soil maps with improved environmental data.Existing methods take all polygons of the same map unit on a map as a whole to extract the soil–environment relationship.Such approach ignores the difference in the environmental conditions represented by individual soil polygons of the same map unit.This paper proposes a method of mining soil–environment relationships from individual soil polygons to update conventional soil maps.The proposed method consists of three major steps.Firstly,the soil–environment relationships represented by each individual polygon on a conventional soil map are extracted in the form of frequency distribution curves for the involved environmental covariates.Secondly,for each environmental covariate,these frequency distribution curves from individual polygons of the same soil map unit are synthesized to form the overall soil–environment relationship for that soil map unit across the mapped area.And lastly,the extracted soil–environment relationships are applied to updating the conventional soil map with new,improved environmental data by adopting a soil land inference model(SoLIM)framework.This study applied the proposed method to updating a conventional soil map of the Raffelson watershed in La Crosse County,Wisconsin,United States.The result from the proposed method was compared with that from the previous method of taking all polygons within the same soil map unit on a map as a whole.Evaluation results with independent soil samples showed that the proposed method exhibited better performance and produced higher accuracy.
文摘This paper takes the basic mathematical operations required to manipulate the cognitive maps. This paper start by presenting all the values that a causal relationship can take. By the using of causal algebra, cognitive map (CC) become not only a graphical representation of a person’s beliefs, an agent or a particular area but also can capture the causal relationships existing between the concepts of a given system in a simple manner. Cognitive maps do not use a conventional algebra;algebra causal is needed to treat.
文摘In this study, non radioactive Digoxigenin labeled ribosomal DNA(rDNA) probes were used for Southern blotting analysis to study the molecular phylogeny of the giant panda and related species. Restriction maps in the regions of rDNA spacers were compared between giant panda( Ailuropoda melanoleuca ), lesser panda( Ailurus fulgens ), Asiatic black bear( Selenarctos thibetanus ), sun bear( Helarctos malayanus ), raccoon( Procyon lotor ) and lynx( Felis lynx ). Phylogenetic trees for these species were constructed using maximum likelihood and parsimony method. The results show that in respect to rDNA RFLPs, the giant panda is more closely related to bear than to lesser panda; while the lesser panda is slightly related to the raccoon.
基金the financial support received from the National Natural Science Foundation of China(Grant No.51505479)the Jiangsu Natural Science Foundation of China(Grant No.BK20150184)the Fundamental Research Funds for the Central Universities(Grant No.2014QNA36)
文摘To develop a fundamental understanding of the flow behavior and optimal hot workability parameters of this material, the hot workability and deformation mechanisms of the as-cast 21Cr EDSS were studied using processing map technology combined with microstructure analysis and isothermal hot compression over the temperature range of 1000-1150 ℃ and strain rate range of 0.01-10 s-1. The processing maps and constitutive equation of peak stress were developed based on Prasad＇s and Murty＇s criteria. The results show that the processing maps exhibit a stable domain at 1000-1150 ℃ and 0.01-1 s-1. The instability domain is exhibited at high strain rates （≥1 s-l）. This implies that Murty＇s criterion can predict the unstable domain with high reliability. The detailed deformation mechanisms are also studied by microstructure observation, showing that the flow localization and microcracking are responsible for the flow instability.
基金This study was funded by the National High-tech R&D Program(863 Program)(2015AA03A501)the Fundamental Research Funds for the Central Universities(N2107013).
文摘In order to determine the safe region of 42CrMo4 steel during hot working and obtain excellent workability,the hot deformation behavior at the temperatures of 850-1150℃and the strain rates of 0.01-10 s^(-1)was investigated through single-pass compression test of thermo-simulation.Through observing and analyzing the true stress-strain curves,the conclusion may be drawn that the flow stress value increases with the decrease in deformation temperature and the increase in strain rate.Raising temperature and reducing strain rate are conductive to dynamic recrystallization(DRX)nucleating and growing,but adiabatic heating caused by higher strain rate can also promote it.Since the Zener-Hollomon(Z)value and dynamic recrystallized grain size(D_(DRX))have completely opposite trends with deformation condition parameters,the expression of Z value and DDRX can be determined as:D_(DRx)=15,567.645Z^(-02174).The processing map and instability map constructed at a strain of 0.9 show that the suitable window for hot working with a true strain of 0.9 is in the temperature range of 970-1150℃and strain rate range of 0.01-0.25 s^(-1),as well as at the temperature of 1150℃ and strain rate range of 0.25-10 s^(-1).The instability phenomenon appears in the process interval of 850-1096℃ and 0.22-10 s^(-1).
