ICAR: endoscopic skull‐base surgery

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Second-order analysis of 2-D steel frames at elevated temperatures

Albermani, F ORCiD: 0000-0001-8540-1724At elevated temperatures, the stress-strain relationship of steel will be nonlinear. When one of the columns of a steel frame is subject to a local fire, the material properties of the column will deteriorate locally. Although the column is weakened, the steel frame will not collapse immediately if the frame is robust enough so that the excessive internal forces of the column can be redistributed by its connecting members. Structural design with robustness consideration can prevent a steel building under local fire from collapse. This paper is to propose a second-order analysis and design method for 2-D steel frames considering the nonlinear stress-strain relationship of the material under elevated temperatures. Results are found to be in line with the Eurocode 3 predicted failure loads

Second-order analysis of 2-D steel frames at elevated temperatures

At elevated temperatures, the stress-strain relationship of steel will be nonlinear. When one of the columns of a steel frame is subject to a local fire, the material properties of the column will deteriorate locally. Although the column is weakened, the steel frame will not collapse immediately if the frame is robust enough so that the excessive internal forces of the column can be redistributed by its connecting members. Structural design with robustness consideration can prevent a steel building under local fire from collapse. This paper is to propose a second-order analysis and design method for 2-D steel frames considering the nonlinear stress-strain relationship of the material under elevated temperatures. Results are found to be in line with the Eurocode 3 predicted failure loads

Intensity of vortices: from soap bubbles to hurricanes

By using a half soap bubble heated from below, we obtain large isolated single vortices whose properties as well as their intensity are measured under different conditions. By studying the effects of rotation of the bubble on the vortex properties, we found that rotation favors vortices near the pole. Rotation also inhibits long life time vortices. The velocity and vorticity profiles of the vortices obtained are well described by a Gaussian vortex. Besides, the intensity of these vortices can be followed over long time spans revealing periods of intensification accompanied by trochoidal motion of the vortex center, features which are reminiscent of the behavior of tropical cyclones. An analysis of this intensification period suggests a simple relation valid for both the vortices observed here and for tropical cyclones