碎屑流是我国山区最危险的地质灾害之一,山区桥墩常受到碎屑流冲击而开裂、倾斜甚至倒塌,给山区桥梁建设、运营带来严重的安全隐患。采用离散元方法(discrete element method,DEM)和有限元方法(finite element method,FEM)耦合的三维数...碎屑流是我国山区最危险的地质灾害之一,山区桥墩常受到碎屑流冲击而开裂、倾斜甚至倒塌,给山区桥梁建设、运营带来严重的安全隐患。采用离散元方法(discrete element method,DEM)和有限元方法(finite element method,FEM)耦合的三维数值模拟方法模拟了碎屑流对双柱式桥墩的冲击效应,并结合斜槽试验,验证了耦合方法的准确性,进一步分析了碎屑流冲击坡度、距离和体积密度对桥墩冲击力的影响规律。结果表明,最大冲击力与碎屑流冲击坡度、距离和体积密度分别呈幂函数(指数大于1)、幂函数(指数小于1)和线性正相关。冲击坡度、距离和体积密度对最大冲击力的敏感度值分别为3.012、0.202、0.804,在桥梁碎屑流灾害防治时需重视冲击坡度和体积密度的影响。将冲击力的数值模拟值与流体动力学模型预测值对比分析表明,流体动力学模型理论公式能较好地预测桥墩所受的最大冲击力,最大预测误差低于23.6%。相关研究结果可为山区桥梁碎屑流灾害防治与设计提供一定的参考依据。展开更多
With the gradual end of the coronavirus disease 2019(COVID-19)pandemic,the reconstruction of students’mental health is urgently necessary.Digital interventions offer advantages such as high accessibility,anonymity,an...With the gradual end of the coronavirus disease 2019(COVID-19)pandemic,the reconstruction of students’mental health is urgently necessary.Digital interventions offer advantages such as high accessibility,anonymity,and accurate identification,which can promote the reconstruction of students’mental health through the provision of psychological support platforms,psychological assessment tools,and online mental health activities.However,we recognize that digital interventions must undergo many adjustments,and corresponding ethical norms require further clarification.It is crucial for different stakeholders to collaborate and work toward maximizing the effectiveness of digital interventions for the reconstruction of mental health after the COVID-19 pandemic.展开更多
[Objective]The paper uses Geographic Information System(ArcGIS)as a platform to discuss the study of DEM data on the digital construction of rural landscape databases and the coupling relationship in geographic space ...[Objective]The paper uses Geographic Information System(ArcGIS)as a platform to discuss the study of DEM data on the digital construction of rural landscape databases and the coupling relationship in geographic space of rural landscape.The aim is to further expand the coverage of China's land space digitization and provide practical theoretical basis and development possibility of quantitative planning for village level administrative zoning research.[Method]In this paper,Xiangyu Village,Junzhuang Town,Mentougou,West Beijing,is selected as the research object,and the document space database of the study area is constructed by building digital elevation model(DEM),ArcGIS stacked map weighting and visual interpretation methods.Moreover,its elevation equivalence,slope direction,and water flow direction are visually analyzed.[Result]The mountainous terrain and hydrological characteristics of Xiangyu Village are roughly consistent with the village layout;the living environment of Xiangyu Village is consistent with the terrain and texture,and it belongs to the rural landscape system of mountains,valleys and small watersheds.[Conclusion]The results obtained through data visualization analysis are basically consistent with the traditional village planning pattern of Xiangyu Village;the rural landscape based on village level administrative divisions is still in the traditional planning stage,and there is great development space for village level geographic spatial survey.Therefore,it is necessary for relevant practitioners to make more contributions to fill the full coverage of China's land space digitization.展开更多
针对鱼类大小分级问题设计了一种自动化高效分级设备,结合鱼的体态形状特征,利用其体厚参数可以较平缓、温和地将鱼进行大小分级,同时增加了倾角调节装置,可根据不同种类的鱼调节设备的结构参数。对设备分级鲫鱼的过程进行了离散元(Disc...针对鱼类大小分级问题设计了一种自动化高效分级设备,结合鱼的体态形状特征,利用其体厚参数可以较平缓、温和地将鱼进行大小分级,同时增加了倾角调节装置,可根据不同种类的鱼调节设备的结构参数。对设备分级鲫鱼的过程进行了离散元(Discrete Element Method,DEM)仿真;设计正交试验,对设备的辊轴转速、倾斜角度以及每秒进鱼量进行了优化,得到设备分级准确率和效率的最优值,为进一步设计优化结构提供参考。展开更多
文摘碎屑流是我国山区最危险的地质灾害之一,山区桥墩常受到碎屑流冲击而开裂、倾斜甚至倒塌,给山区桥梁建设、运营带来严重的安全隐患。采用离散元方法(discrete element method,DEM)和有限元方法(finite element method,FEM)耦合的三维数值模拟方法模拟了碎屑流对双柱式桥墩的冲击效应,并结合斜槽试验,验证了耦合方法的准确性,进一步分析了碎屑流冲击坡度、距离和体积密度对桥墩冲击力的影响规律。结果表明,最大冲击力与碎屑流冲击坡度、距离和体积密度分别呈幂函数(指数大于1)、幂函数(指数小于1)和线性正相关。冲击坡度、距离和体积密度对最大冲击力的敏感度值分别为3.012、0.202、0.804,在桥梁碎屑流灾害防治时需重视冲击坡度和体积密度的影响。将冲击力的数值模拟值与流体动力学模型预测值对比分析表明,流体动力学模型理论公式能较好地预测桥墩所受的最大冲击力,最大预测误差低于23.6%。相关研究结果可为山区桥梁碎屑流灾害防治与设计提供一定的参考依据。
基金Supported by the Tianjin Philosophy and Social Science Planning Project“Research on Value-added Evaluation of Career Adaptability for Engineering Students Oriented towards Outstanding Engineers”,No.TJJXQN22-001.
文摘With the gradual end of the coronavirus disease 2019(COVID-19)pandemic,the reconstruction of students’mental health is urgently necessary.Digital interventions offer advantages such as high accessibility,anonymity,and accurate identification,which can promote the reconstruction of students’mental health through the provision of psychological support platforms,psychological assessment tools,and online mental health activities.However,we recognize that digital interventions must undergo many adjustments,and corresponding ethical norms require further clarification.It is crucial for different stakeholders to collaborate and work toward maximizing the effectiveness of digital interventions for the reconstruction of mental health after the COVID-19 pandemic.
文摘[Objective]The paper uses Geographic Information System(ArcGIS)as a platform to discuss the study of DEM data on the digital construction of rural landscape databases and the coupling relationship in geographic space of rural landscape.The aim is to further expand the coverage of China's land space digitization and provide practical theoretical basis and development possibility of quantitative planning for village level administrative zoning research.[Method]In this paper,Xiangyu Village,Junzhuang Town,Mentougou,West Beijing,is selected as the research object,and the document space database of the study area is constructed by building digital elevation model(DEM),ArcGIS stacked map weighting and visual interpretation methods.Moreover,its elevation equivalence,slope direction,and water flow direction are visually analyzed.[Result]The mountainous terrain and hydrological characteristics of Xiangyu Village are roughly consistent with the village layout;the living environment of Xiangyu Village is consistent with the terrain and texture,and it belongs to the rural landscape system of mountains,valleys and small watersheds.[Conclusion]The results obtained through data visualization analysis are basically consistent with the traditional village planning pattern of Xiangyu Village;the rural landscape based on village level administrative divisions is still in the traditional planning stage,and there is great development space for village level geographic spatial survey.Therefore,it is necessary for relevant practitioners to make more contributions to fill the full coverage of China's land space digitization.
文摘针对鱼类大小分级问题设计了一种自动化高效分级设备,结合鱼的体态形状特征,利用其体厚参数可以较平缓、温和地将鱼进行大小分级,同时增加了倾角调节装置,可根据不同种类的鱼调节设备的结构参数。对设备分级鲫鱼的过程进行了离散元(Discrete Element Method,DEM)仿真;设计正交试验,对设备的辊轴转速、倾斜角度以及每秒进鱼量进行了优化,得到设备分级准确率和效率的最优值,为进一步设计优化结构提供参考。