This work aims to establish a suitable numerical simulation model for hybrid laser-electric arc heat source welding of dissimilar Mg alloys between AZ31 and AZ80. Based on the energy conservation law and Fourier’s la...This work aims to establish a suitable numerical simulation model for hybrid laser-electric arc heat source welding of dissimilar Mg alloys between AZ31 and AZ80. Based on the energy conservation law and Fourier’s law of heat conduction, the differential equations of the three-dimensional temperature field for nonlinear transient heat conduction are built. According to the analysis of nonlinear transient heat transfer, the equations representing initial conditions and boundary conditions are obtained. The “double ellipsoidal heat source + 3D Gaussian heat source”combination was chosen to construct the laser-electric arc hybrid heat source. The weld bead morphologies and the distribution of temperature, stress, displacement and plastic strains are numerically simulated. The actual welding experiments were performed by a hybrid laser-electric arc welding machine. The interaction mechanism between laser and electric arc in the hybrid welding of Mg alloys is discussed in detail. The hybrid heat source can promote the absorption of laser energy and electric arc in the molten pool, resulting in more uniform energy distribution in the molten pool and the corresponding improvement of welding parameters. This work can provide theoretical guidance and data supports for the optimization of the hybrid laser-electric arc welding processes for Mg alloys.展开更多
目的 了解广东省老年人老化态度、社会支持和生活满意度状况及相关性,为广东省老年人健康服务提供参考依据。方法 2019年7—8月在广东省随机抽取2 167名≥60岁的老年人,采用一般情况问卷、老化态度问卷(attitude to aging questionnaire...目的 了解广东省老年人老化态度、社会支持和生活满意度状况及相关性,为广东省老年人健康服务提供参考依据。方法 2019年7—8月在广东省随机抽取2 167名≥60岁的老年人,采用一般情况问卷、老化态度问卷(attitude to aging questionnaire,AAQ)、领悟社会支持量表(perceived social support scale,PSSS)、生活满意度问卷(satisfaction with life scale,SWLS)进行调查。结果 广东省2 167名老年人老化态度总分为(78.857±9.932)分,社会支持总分为(56.019±11.215)分,生活满意度总分为(15.740±3.541)分。不同年龄、性别、受教育程度、婚姻状况、居住地、居住状况、是否有慢性病、参加锻炼及活动、对收入的评价及对与子女关系的评价等特征中,除性别特征外,广东省老年人老化态度得分比较,差异均有统计学意义(均P<0.05);除年龄、性别特征外,广东省老年人社会支持得分比较,差异均有统计学意义(均P<0.05);除年龄、性别特征外,广东省老年人生活满意度得分比较,差异均有统计学意义(均P<0.05)。老化态度总分、社会支持总分和生活满意度总分间均呈正相关关系(均P<0.01)。社会支持在老化态度与生活满意度之间起部分中介作用,中介效应占总效应的36.41%,与子女关系、参加锻炼及社区活动变量在中介模型中起调节作用。结论 与子女关系、参加锻炼及社区活动能影响老年人社会支持水平,影响老年人生活满意度的因素多元而复杂,可以通过提升老化态度和社会支持力度,提升老年人生活满意度。展开更多
基金Project(52004154) supported by the National Natural Science Foundation of ChinaProject(ZR2020QE002) supported by the Shandong Provincial Natural Science Foundation,ChinaProject(6142005190208) supported by the National Key Laboratory Foundation of China。
文摘This work aims to establish a suitable numerical simulation model for hybrid laser-electric arc heat source welding of dissimilar Mg alloys between AZ31 and AZ80. Based on the energy conservation law and Fourier’s law of heat conduction, the differential equations of the three-dimensional temperature field for nonlinear transient heat conduction are built. According to the analysis of nonlinear transient heat transfer, the equations representing initial conditions and boundary conditions are obtained. The “double ellipsoidal heat source + 3D Gaussian heat source”combination was chosen to construct the laser-electric arc hybrid heat source. The weld bead morphologies and the distribution of temperature, stress, displacement and plastic strains are numerically simulated. The actual welding experiments were performed by a hybrid laser-electric arc welding machine. The interaction mechanism between laser and electric arc in the hybrid welding of Mg alloys is discussed in detail. The hybrid heat source can promote the absorption of laser energy and electric arc in the molten pool, resulting in more uniform energy distribution in the molten pool and the corresponding improvement of welding parameters. This work can provide theoretical guidance and data supports for the optimization of the hybrid laser-electric arc welding processes for Mg alloys.
文摘目的 了解广东省老年人老化态度、社会支持和生活满意度状况及相关性,为广东省老年人健康服务提供参考依据。方法 2019年7—8月在广东省随机抽取2 167名≥60岁的老年人,采用一般情况问卷、老化态度问卷(attitude to aging questionnaire,AAQ)、领悟社会支持量表(perceived social support scale,PSSS)、生活满意度问卷(satisfaction with life scale,SWLS)进行调查。结果 广东省2 167名老年人老化态度总分为(78.857±9.932)分,社会支持总分为(56.019±11.215)分,生活满意度总分为(15.740±3.541)分。不同年龄、性别、受教育程度、婚姻状况、居住地、居住状况、是否有慢性病、参加锻炼及活动、对收入的评价及对与子女关系的评价等特征中,除性别特征外,广东省老年人老化态度得分比较,差异均有统计学意义(均P<0.05);除年龄、性别特征外,广东省老年人社会支持得分比较,差异均有统计学意义(均P<0.05);除年龄、性别特征外,广东省老年人生活满意度得分比较,差异均有统计学意义(均P<0.05)。老化态度总分、社会支持总分和生活满意度总分间均呈正相关关系(均P<0.01)。社会支持在老化态度与生活满意度之间起部分中介作用,中介效应占总效应的36.41%,与子女关系、参加锻炼及社区活动变量在中介模型中起调节作用。结论 与子女关系、参加锻炼及社区活动能影响老年人社会支持水平,影响老年人生活满意度的因素多元而复杂,可以通过提升老化态度和社会支持力度,提升老年人生活满意度。