An improved three-dimensional （3-D） experimental visualization methodology is presented tor evaluating the fracture mechanisms of ferritic stainless steels by in-situ tensile testing with an environmental scanning e...An improved three-dimensional （3-D） experimental visualization methodology is presented tor evaluating the fracture mechanisms of ferritic stainless steels by in-situ tensile testing with an environmental scanning electron microscope （ESEM）. The samples were machined with a radial notched shape and a sloped surface. Both planar surface deformation and sloping surface deformation-induced microvoids were observed during dynamic tension experiments, where a greater amount of information could be obtained from the sloping surface. The results showed that microvoids formed at the grain boundaries of highly elongated large grains. The microvoids nucleated in the severely deformed regions grew nearly parallel to the tensile axis, predominantly along the grain boundaries. The microvoids nucleated at the interface of particles and the matrix did not propagate due to the high plasticity of the matrix. The large microvoids propagated and showed a zigzag shape along the grain boundaries,seemingly a consequence of the fracture of the slip bands caused by dislocation pile-ups. The final failure took place due to the reduction of the load-beating area.展开更多
In this study forests were visualized at various scales by placing individual trees into a forest with realistic sizes and densities. Tree images were used from two sources: high quality field photos and images create...In this study forests were visualized at various scales by placing individual trees into a forest with realistic sizes and densities. Tree images were used from two sources: high quality field photos and images created using graphic design software. The terrain, species composition, and tree sizes and density from forest inventory were all represented in GIS data format. In addition, non-tree objects and features that are essential for close-to-reality visualization were combined with the tree images in a 3-D visualization software package. We further portrayed stand level effects by animating a simulated fly-through of a forest. To visualize temporal change, a case study of four different forest patches was animated. The advantages of this approach comparing to other visualization approaches are: (1) it represents the forests with realistic individual tree images; and (2) it maintains both visual and informational realism in a forest viewable from within-stand to landscape scales. Thus, this approach is realistic in two aspects. First, it is almost as realistic as a photograph, and secondly, its information content is actual forest composition, density, and height.展开更多
Public understanding of climate and climate change is of broad societal importance.However,misconceptions regarding reasons for the seasons abound amongst students,teachers,and the public,many of whom believe that sea...Public understanding of climate and climate change is of broad societal importance.However,misconceptions regarding reasons for the seasons abound amongst students,teachers,and the public,many of whom believe that seasonality is caused by large variations in Earth’s distance from the Sun.Misconceptions may be reinforced by textbook illustrations that exaggerate eccentricity or show an inclined view of Earth’s near-circular orbit.Textbook explanations that omit multiple factors influencing seasons,that do not mesh with students’experiences,or that are erroneous,hinder scientifically valid reasoning.Studies show that many teachers share their students’misconceptions,and even when they understand basic concepts,teachers may fail to appreciate the range of factors contributing to seasonal change,or their relative importance.We have therefore developed a learning resource using Google Earth,a virtual globe with other useful,weather-and climate-related visualizations.A classroom test of 27 undergraduates in a public research university showed that 15 improved their test scores after the Google Earth-based laboratory class,whereas 5 disimproved.Mean correct answers rose from 4.7/10 to 6/10,giving a paired t-test value of 0.21.After using Google Earth,students are helped to segue to a heliocentric view.展开更多
文摘An improved three-dimensional （3-D） experimental visualization methodology is presented tor evaluating the fracture mechanisms of ferritic stainless steels by in-situ tensile testing with an environmental scanning electron microscope （ESEM）. The samples were machined with a radial notched shape and a sloped surface. Both planar surface deformation and sloping surface deformation-induced microvoids were observed during dynamic tension experiments, where a greater amount of information could be obtained from the sloping surface. The results showed that microvoids formed at the grain boundaries of highly elongated large grains. The microvoids nucleated in the severely deformed regions grew nearly parallel to the tensile axis, predominantly along the grain boundaries. The microvoids nucleated at the interface of particles and the matrix did not propagate due to the high plasticity of the matrix. The large microvoids propagated and showed a zigzag shape along the grain boundaries,seemingly a consequence of the fracture of the slip bands caused by dislocation pile-ups. The final failure took place due to the reduction of the load-beating area.
文摘In this study forests were visualized at various scales by placing individual trees into a forest with realistic sizes and densities. Tree images were used from two sources: high quality field photos and images created using graphic design software. The terrain, species composition, and tree sizes and density from forest inventory were all represented in GIS data format. In addition, non-tree objects and features that are essential for close-to-reality visualization were combined with the tree images in a 3-D visualization software package. We further portrayed stand level effects by animating a simulated fly-through of a forest. To visualize temporal change, a case study of four different forest patches was animated. The advantages of this approach comparing to other visualization approaches are: (1) it represents the forests with realistic individual tree images; and (2) it maintains both visual and informational realism in a forest viewable from within-stand to landscape scales. Thus, this approach is realistic in two aspects. First, it is almost as realistic as a photograph, and secondly, its information content is actual forest composition, density, and height.
基金This work was supported by the National Science Foundation,Division of Undergraduate Education,through[grant number 1323419]by Google Geo Curriculum Awards to De Paor and Whitmeyer.
文摘Public understanding of climate and climate change is of broad societal importance.However,misconceptions regarding reasons for the seasons abound amongst students,teachers,and the public,many of whom believe that seasonality is caused by large variations in Earth’s distance from the Sun.Misconceptions may be reinforced by textbook illustrations that exaggerate eccentricity or show an inclined view of Earth’s near-circular orbit.Textbook explanations that omit multiple factors influencing seasons,that do not mesh with students’experiences,or that are erroneous,hinder scientifically valid reasoning.Studies show that many teachers share their students’misconceptions,and even when they understand basic concepts,teachers may fail to appreciate the range of factors contributing to seasonal change,or their relative importance.We have therefore developed a learning resource using Google Earth,a virtual globe with other useful,weather-and climate-related visualizations.A classroom test of 27 undergraduates in a public research university showed that 15 improved their test scores after the Google Earth-based laboratory class,whereas 5 disimproved.Mean correct answers rose from 4.7/10 to 6/10,giving a paired t-test value of 0.21.After using Google Earth,students are helped to segue to a heliocentric view.
