Artificially controlling the solid-state precipitation in aluminum (Al) alloys is an efficient way to achieve well-performed properties,and the microalloying strategy is the most frequently adopted method for such a p...Artificially controlling the solid-state precipitation in aluminum (Al) alloys is an efficient way to achieve well-performed properties,and the microalloying strategy is the most frequently adopted method for such a purpose.In this paper,recent advances in lengthscale-dependent scandium (Sc) microalloying effects in Al-Cu model alloys are reviewed.In coarse-grained Al-Cu alloys,the Sc-aided Cu/Sc/vacancies complexes that act as heterogeneous nuclei and Sc segregation at the θ′-Al_(2)Cu/matrix interface that reduces interfacial energy contribute significantly to θ′precipitation.By grain size refinement to the fine/ultrafine-grained scale,the strongly bonded Cu/Sc/vacancies complexes inhibit Cu and vacancy diffusing toward grain boundaries,promoting the desired intragranular θ′precipitation.At nanocrystalline scale,the applied high strain producing high-density vacancies results in the formation of a large quantity of (Cu Sc,vacancy)-rich atomic complexes with high thermal stability,outstandingly improving the strength/ductility synergy and preventing the intractable low-temperature precipitation.This review recommends the use of microalloying technology to modify the precipitation behaviors toward better combined mechanical properties and thermal stability in Al alloys.展开更多
The large blast furnace is essential equipment in the process of iron and steel manufacturing. Due to the complex operation process and frequent fluctuations of variables, conventional monitoring methods often bring f...The large blast furnace is essential equipment in the process of iron and steel manufacturing. Due to the complex operation process and frequent fluctuations of variables, conventional monitoring methods often bring false alarms. To address the above problem, an ensemble of greedy dynamic principal component analysis-Gaussian mixture model(EGDPCA-GMM) is proposed in this paper. First, PCA-GMM is introduced to deal with the collinearity and the non-Gaussian distribution of blast furnace data.Second, in order to explain the dynamics of data, the greedy algorithm is used to determine the extended variables and their corresponding time lags, so as to avoid introducing unnecessary noise. Then the bagging ensemble is adopted to cooperate with greedy extension to eliminate the randomness brought by the greedy algorithm and further reduce the false alarm rate(FAR) of monitoring results. Finally, the algorithm is applied to the blast furnace of a large iron and steel group in South China to verify performance.Compared with the basic algorithms, the proposed method achieves lowest FAR, while keeping missed alarm rate(MAR) remain stable.展开更多
The Swift effect of Mg alloy is sensitive to initial texture.However,dislocation slip is the main deformation mechanism during torsion of Mg alloy.The underlying relation of Swift effect and dislocation slip is still ...The Swift effect of Mg alloy is sensitive to initial texture.However,dislocation slip is the main deformation mechanism during torsion of Mg alloy.The underlying relation of Swift effect and dislocation slip is still not clarified.The effect of stress state and pre-straining on Swift effect was studied experimentally during free-end torsion for an extruded AZ31 alloy.The free-end torsion was performed with axial tension and compression stress which is lower than yield stress.It is found that the transition of axial deformation from contraction to elongation occurs when the axial stress changes from negative to positive.The pre-dislocations introduced by pre-tension promote axial shortening during torsion.While the pre-twins introduced by pre-compression are inhibition of axial shortening.The change of axial deformation is attributed to competition between twinning and prismatic slip.The axial shortening of extruded Mg alloy is generated by tensile twinning leading to c-axis strain.In contrast,the axial elongation can be generated by the activation of prismatic slip.The magnitude of axial strain generated by twinning is larger than that by prismatic slip.Moreover,the occurrence of detwinning results in axial elongation at low shear strain.展开更多
利用最新的波茨坦地磁场球谐模型(Potsdam Magnetic Model of the Earth,POMME)进行仿真实验,分别模拟出不同卫星轨道高度下的磁测数据.根据仿真的观测数据反演地壳磁场的高斯球谐系数,对反演结果进行对比和分析,总结出卫星轨道高度对...利用最新的波茨坦地磁场球谐模型(Potsdam Magnetic Model of the Earth,POMME)进行仿真实验,分别模拟出不同卫星轨道高度下的磁测数据.根据仿真的观测数据反演地壳磁场的高斯球谐系数,对反演结果进行对比和分析,总结出卫星轨道高度对反演结果的影响.针对CHAMP卫星实测数据进行地壳磁场反演,由不同轨道高度磁测数据反演得到的磁场(Magnetic Field,MF)系列模型,验证卫星轨道高度对反演的影响,从而为磁测卫星系统设计论证指标中的卫星轨道高度设计提供一定的参考和指导.展开更多
In this paper, the relationship between anisotropic mechanical properties and the corresponding microstructure evolution of wrought magnesium alloys is critically reviewed. Experimental observations of the strong anis...In this paper, the relationship between anisotropic mechanical properties and the corresponding microstructure evolution of wrought magnesium alloys is critically reviewed. Experimental observations of the strong anisotropy(including the strength differential effect) induced by texture and twinning are discussed under different loading conditions(i.e., monotonic, cyclic and multiaxial loading). An accurate constitutive model is essential to describe the mechanical responses and to predict the forming performance considering engineering applications. Therefore, macroscale constitutive modeling of the anisotropy of magnesium alloys with directional distortional hardening are comprehensively reviewed with different approaches. To clarify the origin of the anisotropic behavior, physics-based mesoscale modeling of the anisotropy is also compared in detail.展开更多
Hepatic alveolar echinococcosis (HAE) is a lethal infectious disease caused by the larval stage of Echinococcus multilocularis.To date,radical resection combined with albendazole is considered the major treatment for ...Hepatic alveolar echinococcosis (HAE) is a lethal infectious disease caused by the larval stage of Echinococcus multilocularis.To date,radical resection combined with albendazole is considered the major treatment for patients with HAE.However,many patients miss the best time for diagnosis and resection due to patient delay,doctor delay,or long distances to specialized centers.展开更多
Large plastic deformation commonly occurs during the practical forming process in industries.Compared with uniaxial tension/compression,torsion is a more effective approach to investigate mechanical behavior under lar...Large plastic deformation commonly occurs during the practical forming process in industries.Compared with uniaxial tension/compression,torsion is a more effective approach to investigate mechanical behavior under large deformation.The response of the large strain torsion of magnesium alloy is sensitive to the initial texture and twinning.Therefore,an extruded AZ31 alloy was pre-stressed in tension and compression to introduce dislocations and twins in the current work.Subsequently,torsion tests were conducted to clarify the effects of twinning and dislocation on subsequent deformation responses.The corresponding microstructure and deformation mechanisms were explored on the basis of viscoplastic self-consistent(VPSC)modeling.The experimental observations on stress-strain responses and pole figures were captured by simulation work.It was found that twins make less contribution to plastic deformation,which results in small change in texture direction under pure torsion and torsion after pretension.The activity of the slip/twin system and the mechanical properties are affected by different initial textures and active conditions of the system.Moreover,the stress state during combined tension-torsion loading benefits the reduction of texture intensity.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52201135,52271115,U23A6013,92360301,and U2330203)the 111 Project of China(No.BP2018008)+1 种基金the Shaanxi Province Innovation Team Project,China(No.2024RS-CXTD-58)supported by the International Joint Laboratory for Micro/Nano Manufacturing and Measurement Technologies and by the open research fund of Suzhou Laboratory。
文摘Artificially controlling the solid-state precipitation in aluminum (Al) alloys is an efficient way to achieve well-performed properties,and the microalloying strategy is the most frequently adopted method for such a purpose.In this paper,recent advances in lengthscale-dependent scandium (Sc) microalloying effects in Al-Cu model alloys are reviewed.In coarse-grained Al-Cu alloys,the Sc-aided Cu/Sc/vacancies complexes that act as heterogeneous nuclei and Sc segregation at the θ′-Al_(2)Cu/matrix interface that reduces interfacial energy contribute significantly to θ′precipitation.By grain size refinement to the fine/ultrafine-grained scale,the strongly bonded Cu/Sc/vacancies complexes inhibit Cu and vacancy diffusing toward grain boundaries,promoting the desired intragranular θ′precipitation.At nanocrystalline scale,the applied high strain producing high-density vacancies results in the formation of a large quantity of (Cu Sc,vacancy)-rich atomic complexes with high thermal stability,outstandingly improving the strength/ductility synergy and preventing the intractable low-temperature precipitation.This review recommends the use of microalloying technology to modify the precipitation behaviors toward better combined mechanical properties and thermal stability in Al alloys.
基金supported by the National Natural Science Foundation of China (61903326, 61933015)。
文摘The large blast furnace is essential equipment in the process of iron and steel manufacturing. Due to the complex operation process and frequent fluctuations of variables, conventional monitoring methods often bring false alarms. To address the above problem, an ensemble of greedy dynamic principal component analysis-Gaussian mixture model(EGDPCA-GMM) is proposed in this paper. First, PCA-GMM is introduced to deal with the collinearity and the non-Gaussian distribution of blast furnace data.Second, in order to explain the dynamics of data, the greedy algorithm is used to determine the extended variables and their corresponding time lags, so as to avoid introducing unnecessary noise. Then the bagging ensemble is adopted to cooperate with greedy extension to eliminate the randomness brought by the greedy algorithm and further reduce the false alarm rate(FAR) of monitoring results. Finally, the algorithm is applied to the blast furnace of a large iron and steel group in South China to verify performance.Compared with the basic algorithms, the proposed method achieves lowest FAR, while keeping missed alarm rate(MAR) remain stable.
基金Financial support from the projects by the NSFC(51771166)the Hebei Natural Science Foundation(E2019203452,E2021203011)+4 种基金the central government guiding local science and technology development(216Z1001G)the talent project of human resources and social security department of Hebei province(A202002002)the key project of department of education of Hebei province(ZD2021107)Graduate Innovation Program of Hebei province(CXZZBS2020053)The work was supported by the State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology(P2020-013).
文摘The Swift effect of Mg alloy is sensitive to initial texture.However,dislocation slip is the main deformation mechanism during torsion of Mg alloy.The underlying relation of Swift effect and dislocation slip is still not clarified.The effect of stress state and pre-straining on Swift effect was studied experimentally during free-end torsion for an extruded AZ31 alloy.The free-end torsion was performed with axial tension and compression stress which is lower than yield stress.It is found that the transition of axial deformation from contraction to elongation occurs when the axial stress changes from negative to positive.The pre-dislocations introduced by pre-tension promote axial shortening during torsion.While the pre-twins introduced by pre-compression are inhibition of axial shortening.The change of axial deformation is attributed to competition between twinning and prismatic slip.The axial shortening of extruded Mg alloy is generated by tensile twinning leading to c-axis strain.In contrast,the axial elongation can be generated by the activation of prismatic slip.The magnitude of axial strain generated by twinning is larger than that by prismatic slip.Moreover,the occurrence of detwinning results in axial elongation at low shear strain.
文摘利用最新的波茨坦地磁场球谐模型(Potsdam Magnetic Model of the Earth,POMME)进行仿真实验,分别模拟出不同卫星轨道高度下的磁测数据.根据仿真的观测数据反演地壳磁场的高斯球谐系数,对反演结果进行对比和分析,总结出卫星轨道高度对反演结果的影响.针对CHAMP卫星实测数据进行地壳磁场反演,由不同轨道高度磁测数据反演得到的磁场(Magnetic Field,MF)系列模型,验证卫星轨道高度对反演的影响,从而为磁测卫星系统设计论证指标中的卫星轨道高度设计提供一定的参考和指导.
基金Financial support from the projects by the NSFC [51771166]Chongqing Special Project of Science and Technology Innovation (cstc2020yszx-jcyj X0001)+5 种基金the Hebei Natural Science Foundation [E2019203452, E2021203011]the talent project of human resources and social security department of Hebei province [A202002002]the key project of department of education of Hebei province [ZD2021107]project of the central government guiding local science and technology development [216Z1001G]Cultivation Project for Basic Research and Innovation of Yanshan University [2021LGZD002]supported by the State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology [P2020-013]。
文摘In this paper, the relationship between anisotropic mechanical properties and the corresponding microstructure evolution of wrought magnesium alloys is critically reviewed. Experimental observations of the strong anisotropy(including the strength differential effect) induced by texture and twinning are discussed under different loading conditions(i.e., monotonic, cyclic and multiaxial loading). An accurate constitutive model is essential to describe the mechanical responses and to predict the forming performance considering engineering applications. Therefore, macroscale constitutive modeling of the anisotropy of magnesium alloys with directional distortional hardening are comprehensively reviewed with different approaches. To clarify the origin of the anisotropic behavior, physics-based mesoscale modeling of the anisotropy is also compared in detail.
基金supported by a grant from the Non-proft Central Research Institute Fund of Chinese Academy of Medical Sciences (No. 2019PT320004)。
文摘Hepatic alveolar echinococcosis (HAE) is a lethal infectious disease caused by the larval stage of Echinococcus multilocularis.To date,radical resection combined with albendazole is considered the major treatment for patients with HAE.However,many patients miss the best time for diagnosis and resection due to patient delay,doctor delay,or long distances to specialized centers.
基金financially supported by the projects by the National Natural Science Foundation of China (No. 51771166)the Hebei Natural Science Foundation, China (Nos. E2019203452 and E2021203011)+4 种基金the central government guiding local science and technology development (No. 216Z1001G)the talent project of Human Resources and Social Security Department of Hebei Province, China (No. A202002002)the key project of the Department of Education of Hebei Province (No. ZD2021107)the Cultivation Project for Basic Research and Innovation of Yanshan University (No. 2021LGZD002)the State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, China (No. P2020-013)
文摘Large plastic deformation commonly occurs during the practical forming process in industries.Compared with uniaxial tension/compression,torsion is a more effective approach to investigate mechanical behavior under large deformation.The response of the large strain torsion of magnesium alloy is sensitive to the initial texture and twinning.Therefore,an extruded AZ31 alloy was pre-stressed in tension and compression to introduce dislocations and twins in the current work.Subsequently,torsion tests were conducted to clarify the effects of twinning and dislocation on subsequent deformation responses.The corresponding microstructure and deformation mechanisms were explored on the basis of viscoplastic self-consistent(VPSC)modeling.The experimental observations on stress-strain responses and pole figures were captured by simulation work.It was found that twins make less contribution to plastic deformation,which results in small change in texture direction under pure torsion and torsion after pretension.The activity of the slip/twin system and the mechanical properties are affected by different initial textures and active conditions of the system.Moreover,the stress state during combined tension-torsion loading benefits the reduction of texture intensity.
