In recent years, climate change has emerged as one of the most pressing environmental issues globally. Morocco, like many other countries, has been significantly affected by these changes, particularly over the past d...In recent years, climate change has emerged as one of the most pressing environmental issues globally. Morocco, like many other countries, has been significantly affected by these changes, particularly over the past decade. In this context, we aim to examine the spatial and temporal distribution of rainfall as a hydrological indicator to understand its impact on the hydrological dynamics of the upper Oum Er-Rbia basin. The Oum Er-Rbia basin is one of the largest watersheds in Morocco in terms of water resources, after the Sebou basin. Besides, the studied area covers an area of 6965 km2. The altitudes are between 2410 m and 415 m. Oum Er-Rbia river takes its source from the Middle Atlas at 2400 m altitude and crosses the Middle Atlas range, the Tadla plain. It shows diversity in relief with diverse structural forms. It is fed by several permanent and seasonal tributaries. The present study consists of analyzing the variations of rainfall events through a statistical analysis of rainfall data provided by the reference stations in the Upper Oum Erbia basin for a chronicle of (1934-2023), and spatializing the precipitation at different scales, annual and monthly, through the rainfall data, provided by 33 rainfall stations, with a chronicle of 30 years, inter-station period (1984-2013). From a methodological point of view, this study places us within a palette of concepts of spatialization that are said to be normative or traditional and are part of the set of methods existing in the field of spatialization. The main objective of this paper is to extract all the information that can inform us about the rainfall characteristics of this period, to determine the rainfall trends and to identify the spatial and temporal rainfall distributions. All this is in order to follow, understand and determine the nature of the impact of climate variability on the hydrological functioning in the upper basin of Oum Er-Rbia.展开更多
采用激光粉末床熔融(laser powder bed fusion,LPBF)技术成形的Al-Mg-Sc-Zr合金不易开裂、力学性能好,但Sc价格昂贵,因此寻找能替代Sc的元素十分必要。本文以气雾化粉末为原料,采用LPBF技术制备Al-Mg-Sc-Er-Zr合金。通过流体静力天平测...采用激光粉末床熔融(laser powder bed fusion,LPBF)技术成形的Al-Mg-Sc-Zr合金不易开裂、力学性能好,但Sc价格昂贵,因此寻找能替代Sc的元素十分必要。本文以气雾化粉末为原料,采用LPBF技术制备Al-Mg-Sc-Er-Zr合金。通过流体静力天平测量密度和使用金相显微镜观察缺陷,以优化激光工艺参数;采用维氏硬度计测量硬度和使用万能力学试验机进行拉伸实验,以优化时效工艺参数;采用扫描电镜、透射电镜对合金组织进行表征并研究其强化机理。结果表明:优化的LPBF工艺参数为:激光功率300W,扫描速度900mm/s;优化的时效工艺参数为:时效温度325℃,时效时间4h。LPBF制备的Al-Mg-Sc-Er-Zr合金呈典型双峰晶粒结构,熔池边界为细小等轴晶,熔池内为粗大柱状晶。经325℃/4h时效处理后,合金的抗拉强度达565MPa,屈服强度达520MPa,伸长率为14.5%,硬度(HV)由时效前的118提升至163。时效处理后形成的Mg2Si粒子和纳米Al3(Sc,Zr)粒子能够协同钉扎晶界,提高合金强度。展开更多
文摘In recent years, climate change has emerged as one of the most pressing environmental issues globally. Morocco, like many other countries, has been significantly affected by these changes, particularly over the past decade. In this context, we aim to examine the spatial and temporal distribution of rainfall as a hydrological indicator to understand its impact on the hydrological dynamics of the upper Oum Er-Rbia basin. The Oum Er-Rbia basin is one of the largest watersheds in Morocco in terms of water resources, after the Sebou basin. Besides, the studied area covers an area of 6965 km2. The altitudes are between 2410 m and 415 m. Oum Er-Rbia river takes its source from the Middle Atlas at 2400 m altitude and crosses the Middle Atlas range, the Tadla plain. It shows diversity in relief with diverse structural forms. It is fed by several permanent and seasonal tributaries. The present study consists of analyzing the variations of rainfall events through a statistical analysis of rainfall data provided by the reference stations in the Upper Oum Erbia basin for a chronicle of (1934-2023), and spatializing the precipitation at different scales, annual and monthly, through the rainfall data, provided by 33 rainfall stations, with a chronicle of 30 years, inter-station period (1984-2013). From a methodological point of view, this study places us within a palette of concepts of spatialization that are said to be normative or traditional and are part of the set of methods existing in the field of spatialization. The main objective of this paper is to extract all the information that can inform us about the rainfall characteristics of this period, to determine the rainfall trends and to identify the spatial and temporal rainfall distributions. All this is in order to follow, understand and determine the nature of the impact of climate variability on the hydrological functioning in the upper basin of Oum Er-Rbia.
文摘采用激光粉末床熔融(laser powder bed fusion,LPBF)技术成形的Al-Mg-Sc-Zr合金不易开裂、力学性能好,但Sc价格昂贵,因此寻找能替代Sc的元素十分必要。本文以气雾化粉末为原料,采用LPBF技术制备Al-Mg-Sc-Er-Zr合金。通过流体静力天平测量密度和使用金相显微镜观察缺陷,以优化激光工艺参数;采用维氏硬度计测量硬度和使用万能力学试验机进行拉伸实验,以优化时效工艺参数;采用扫描电镜、透射电镜对合金组织进行表征并研究其强化机理。结果表明:优化的LPBF工艺参数为:激光功率300W,扫描速度900mm/s;优化的时效工艺参数为:时效温度325℃,时效时间4h。LPBF制备的Al-Mg-Sc-Er-Zr合金呈典型双峰晶粒结构,熔池边界为细小等轴晶,熔池内为粗大柱状晶。经325℃/4h时效处理后,合金的抗拉强度达565MPa,屈服强度达520MPa,伸长率为14.5%,硬度(HV)由时效前的118提升至163。时效处理后形成的Mg2Si粒子和纳米Al3(Sc,Zr)粒子能够协同钉扎晶界,提高合金强度。
基金National Natural Science Foundation of China(No.81001518)Fok Ying-tong Education Foundation for Young Teachers in Colleges and Universities Fund(No.131042)+1 种基金China Postdoctoral Science Fund(No.2012M521526,No.2013T60771)Hunan Province Department of Science and Technology Project(No.2013RS4038)~~
基金supported by the National Natural Science Foundation of China(No.30970353)the Key Laboratory Project of Department of Education of Liaoning Province+3 种基金China(No.LS2010095)the College Students' Innovative Project of Educational DepartmentLiaoning ProvinceChina(No.CSXL201210165007)
