以某轿车前后车门内板为例,探讨复杂钣金件的逆向设计过程和方法。通过手持式三维激光扫描仪的非接触式测量获取前后车门内板的点云数据。利用Geomagic Studio 12软件进行前期点云处理。基于CATIA V5 R17软件平台的自由曲面、创成式外...以某轿车前后车门内板为例,探讨复杂钣金件的逆向设计过程和方法。通过手持式三维激光扫描仪的非接触式测量获取前后车门内板的点云数据。利用Geomagic Studio 12软件进行前期点云处理。基于CATIA V5 R17软件平台的自由曲面、创成式外形设计、数字化外形编辑器、快速曲面重构等模块完成前后车门内板的曲面重构,并进行相应的曲面质量检查。对复杂钣金件的逆向建模流程和方法以及车门内板曲面质量的评价指标进行了相关探索。展开更多
Understanding the relationship between landscape pattems and ecological processes has been a central yet challenging research theme in landscape ecology. Over the past decades, many landscape metrics have been propose...Understanding the relationship between landscape pattems and ecological processes has been a central yet challenging research theme in landscape ecology. Over the past decades, many landscape metrics have been proposed but few directly incorporated ecological processes. In this paper, we developed a landscape index, namely, location-weighted landscape index （LWLI） to highlight the role of landscape type in ecological processes, such as nutrient losses and soil erosion. Within the framework of the Lorenz curve theory, we develop this index by integrating land- scape pattern and point-based measurements at a watershed scale. The index can be used to characterize the contribution of landscape pattern to ecological processes （e.g. nutrient losses） with respect to a specific monitoring point in a watershed. Through a case study on nutrient losses in an agricultural area in northeastern China, we found that nutrient losses tended to be higher for a watershed with a higher LWLI value, and vice versa. It implied that LWLI can be used to evaluate the potential risk of nutrient losses or soil erosion by comparing their values across watersheds. In addition, this index can be extended to characterize ecological processes, such as the effect of landscape pattern on wildlife inhabitation and urban heat island effect. Finally, we discuss several problems that should be paid attention to when applying this index to a heterogeneous landscape site.展开更多
The term ‘profile machining’ is used to refer to the milling of vertical surfaces described by profile curves. Profile machining requires higher precision (1/1000 mm) than regular 3D machining (1/100 mm) with the er...The term ‘profile machining’ is used to refer to the milling of vertical surfaces described by profile curves. Profile machining requires higher precision (1/1000 mm) than regular 3D machining (1/100 mm) with the erosion of sharp vertices should being especially avoided. Although, profile machining is very essential for making trimming and flange dies, it seldom brought into focus. This paper addresses the technological requirements of profile machining including machining width and depth control, minimizing toolware, and protecting sharp vertices. Issues of controller alarms are also addressed.展开更多
文摘以某轿车前后车门内板为例,探讨复杂钣金件的逆向设计过程和方法。通过手持式三维激光扫描仪的非接触式测量获取前后车门内板的点云数据。利用Geomagic Studio 12软件进行前期点云处理。基于CATIA V5 R17软件平台的自由曲面、创成式外形设计、数字化外形编辑器、快速曲面重构等模块完成前后车门内板的曲面重构,并进行相应的曲面质量检查。对复杂钣金件的逆向建模流程和方法以及车门内板曲面质量的评价指标进行了相关探索。
基金Under the auspices of Chinese Academy of Sciences (No. KZCX2-YW-421)National Natural Science Foundation of China (No. 40621061, 30570319)
文摘Understanding the relationship between landscape pattems and ecological processes has been a central yet challenging research theme in landscape ecology. Over the past decades, many landscape metrics have been proposed but few directly incorporated ecological processes. In this paper, we developed a landscape index, namely, location-weighted landscape index （LWLI） to highlight the role of landscape type in ecological processes, such as nutrient losses and soil erosion. Within the framework of the Lorenz curve theory, we develop this index by integrating land- scape pattern and point-based measurements at a watershed scale. The index can be used to characterize the contribution of landscape pattern to ecological processes （e.g. nutrient losses） with respect to a specific monitoring point in a watershed. Through a case study on nutrient losses in an agricultural area in northeastern China, we found that nutrient losses tended to be higher for a watershed with a higher LWLI value, and vice versa. It implied that LWLI can be used to evaluate the potential risk of nutrient losses or soil erosion by comparing their values across watersheds. In addition, this index can be extended to characterize ecological processes, such as the effect of landscape pattern on wildlife inhabitation and urban heat island effect. Finally, we discuss several problems that should be paid attention to when applying this index to a heterogeneous landscape site.
文摘The term ‘profile machining’ is used to refer to the milling of vertical surfaces described by profile curves. Profile machining requires higher precision (1/1000 mm) than regular 3D machining (1/100 mm) with the erosion of sharp vertices should being especially avoided. Although, profile machining is very essential for making trimming and flange dies, it seldom brought into focus. This paper addresses the technological requirements of profile machining including machining width and depth control, minimizing toolware, and protecting sharp vertices. Issues of controller alarms are also addressed.
