The influence of quench transfer time on the microstructure and mechanical properties of 7055 aluminum alloy with and without zirconium was investigated by tensile properties test,optical microscopy,scanning electron ...The influence of quench transfer time on the microstructure and mechanical properties of 7055 aluminum alloy with and without zirconium was investigated by tensile properties test,optical microscopy,scanning electron microscopy and transmission electron microscopy.For the Zr-free alloy,the strength increases to the highest value at 20 s with transfer time,and then decreases slightly.The elongation decreases slowly with transfer time within 20 s,and more rapidly after 20 s.For the Zr-containing alloy,prolonging transfer time within 20 s results in slight decrease in the strength and elongation,and rapid drop of which is observed after 20 s.For the Zr-free alloy,prolonging transfer time can increase the percentage of intergranular fracture,which is mainly caused by wide grain boundary precipitate free zone.The failure mode of the Zr-containing alloy is modified from the predominant transgranular void growth and intergranular fracture to transgranular shear and intergranular fracture with increase in the transfer time,which is attributed to the wider grain boundary precipitate free zone and coarse equilibrium η phases in the matrix.展开更多
时间序列分类是时间序列分析的基础。然而,现有的时间序列分类方法对应的形态特征并不能作为分类依据,且通道间的特征通过图上的单一权重刻画不够准确,导致分类精度不高。因此,提出一种融合衍生特征的时间序列事件分类方法(TSEC-FDF)。...时间序列分类是时间序列分析的基础。然而,现有的时间序列分类方法对应的形态特征并不能作为分类依据,且通道间的特征通过图上的单一权重刻画不够准确,导致分类精度不高。因此,提出一种融合衍生特征的时间序列事件分类方法(TSEC-FDF)。首先,在时间序列上构建时间序列事件集合后,根据每个时间序列事件构建突变图、协同图、启发图,以减少噪声对高维特征的干扰;其次,融合多图的特征作为衍生特征,并抽取时间序列事件的多个时间级别的特征;最后,提出一种融合衍生特征的多图卷积分类模型级联时间序列和图特征作为时间序列事件的高维特征。实验结果表明,与TF-C(Time-Frequency Consistency)和BiLSTM+隐马尔可夫模型(Bi-directional Long Short-Term Memory-Hidden Markov Model,BL-HMM)方法相比,TSEC-FDF在4个真实数据集上的准确率、精确率、查全率、F1值、AUROC(Area Under the Receiver Operating Characteristic curve)以及AUPRC(Area Under the Precision versus Recall Curve)至少提升了3.2%、4.7%、7.8%、6.3%、0.9%和2.2%。展开更多
基金Project(2005CB623706) supported by the Major State Basic Research Development Program of ChinaProject(50230310) supported by the National Natural Science Foundation of China
文摘The influence of quench transfer time on the microstructure and mechanical properties of 7055 aluminum alloy with and without zirconium was investigated by tensile properties test,optical microscopy,scanning electron microscopy and transmission electron microscopy.For the Zr-free alloy,the strength increases to the highest value at 20 s with transfer time,and then decreases slightly.The elongation decreases slowly with transfer time within 20 s,and more rapidly after 20 s.For the Zr-containing alloy,prolonging transfer time within 20 s results in slight decrease in the strength and elongation,and rapid drop of which is observed after 20 s.For the Zr-free alloy,prolonging transfer time can increase the percentage of intergranular fracture,which is mainly caused by wide grain boundary precipitate free zone.The failure mode of the Zr-containing alloy is modified from the predominant transgranular void growth and intergranular fracture to transgranular shear and intergranular fracture with increase in the transfer time,which is attributed to the wider grain boundary precipitate free zone and coarse equilibrium η phases in the matrix.
文摘时间序列分类是时间序列分析的基础。然而,现有的时间序列分类方法对应的形态特征并不能作为分类依据,且通道间的特征通过图上的单一权重刻画不够准确,导致分类精度不高。因此,提出一种融合衍生特征的时间序列事件分类方法(TSEC-FDF)。首先,在时间序列上构建时间序列事件集合后,根据每个时间序列事件构建突变图、协同图、启发图,以减少噪声对高维特征的干扰;其次,融合多图的特征作为衍生特征,并抽取时间序列事件的多个时间级别的特征;最后,提出一种融合衍生特征的多图卷积分类模型级联时间序列和图特征作为时间序列事件的高维特征。实验结果表明,与TF-C(Time-Frequency Consistency)和BiLSTM+隐马尔可夫模型(Bi-directional Long Short-Term Memory-Hidden Markov Model,BL-HMM)方法相比,TSEC-FDF在4个真实数据集上的准确率、精确率、查全率、F1值、AUROC(Area Under the Receiver Operating Characteristic curve)以及AUPRC(Area Under the Precision versus Recall Curve)至少提升了3.2%、4.7%、7.8%、6.3%、0.9%和2.2%。
