The virtual reality based motion simulation of the guide wire and the catheter inside specific vascular structures can benefit a lot for the endovascular intervention. A fast and well-performed collision cancellation ...The virtual reality based motion simulation of the guide wire and the catheter inside specific vascular structures can benefit a lot for the endovascular intervention. A fast and well-performed collision cancellation algorithm is proposed based on the geometric analysis and the angular propagation （AP）, and a 3-D real-time interactive system is developed for the motion simulation of the guide wire and the catheter inside the specific patient vascular. The guide wire or the catheter is modeled as the ＂multi-body＂ representation and properties are defined by its intrinsic characteristics. The motion of the guide wire or the catheter inside the vascular is guided by the collision detection and the collision cancellation algorithm. Finally, a relaxation procedure is used to achieve more realistic status. Experimental results show that the behavior of the guide wire or the catheter depends on the defined parameters. The real-time simulation can be achieved. The result shows that the simulation system is effective and promising.展开更多
Computational fluid dynamics(CFD) has recently emerged as an effective tool for the investigation of the hydraulic parameters and efficiency of tray towers.The computation domain was established for two types of orien...Computational fluid dynamics(CFD) has recently emerged as an effective tool for the investigation of the hydraulic parameters and efficiency of tray towers.The computation domain was established for two types of oriented valves within a tray and meshed into two parts with different grid types and sizes.The volume fraction correlation concerning inter-phase momentum transfer source was fitted based on experimental data,and built in UDF for simulation.The flow pattern of oriented valve tray under different operating conditions was simulated under Eulerian-Eulerian framework with realizable k-ε model.The predicted liquid height from CFD simulation was in good agreement with the results of pressure drop and volume fraction correlations.Meanwhile,the velocity distribution and volume fraction of the two phases were demonstrated and analyzed,which are useful in design and analysis of the column trays.展开更多
The effect of a guide vane installed at the elbow on flow-induced noise and vibration is investigated in the range of Reynolds numbers from 1.70×10^5 to 6.81×10^5, and the position of guide vane is determine...The effect of a guide vane installed at the elbow on flow-induced noise and vibration is investigated in the range of Reynolds numbers from 1.70×10^5 to 6.81×10^5, and the position of guide vane is determined by publications. The turbulent flow in the piping elbow is simulated with large eddy simulation （LES）. Following this, a hybrid method of combining LES and Lighthill＇s acoustic analogy theory is used to simulate the hydrodynamic noise and sound sources are solved as volume sources in code Actran. In addition, the flow-induced vibration of the piping elbow is investigated based on a fluid-structure interaction （FSI） code. The LES results indicate that the range of vortex zone in the elbow without the guide vane is larger than the case with the guide vane, and the guide vane is effective in reducing flow-induced noise and vibration in the 90° piping elbow at different Reynolds numbers.展开更多
To reveal the possible mechanism of silica deposition in higher plants, lignin was isolated from rice straw following a modified method to conduct a simulation experiment in vitro. UV and infrared absorption spectra s...To reveal the possible mechanism of silica deposition in higher plants, lignin was isolated from rice straw following a modified method to conduct a simulation experiment in vitro. UV and infrared absorption spectra showed that the substance had the unique characteristics of pure lignin. The presence of silicon in the precipitation was revealed by TEM (transmission electron microscopy) with EDXA (energy dispersive X-ray analysis) device. It was found that in the borax solution where lignin precipi-tation occurred silica-lignin co-precipitation was produced but not in the DMSO solution where lignin was broken into its com-position compounds and did not precipitate. This means that it is macromolecular lignin itself but not its compounds that could induce silica deposition in higher plants.展开更多
文摘The virtual reality based motion simulation of the guide wire and the catheter inside specific vascular structures can benefit a lot for the endovascular intervention. A fast and well-performed collision cancellation algorithm is proposed based on the geometric analysis and the angular propagation （AP）, and a 3-D real-time interactive system is developed for the motion simulation of the guide wire and the catheter inside the specific patient vascular. The guide wire or the catheter is modeled as the ＂multi-body＂ representation and properties are defined by its intrinsic characteristics. The motion of the guide wire or the catheter inside the vascular is guided by the collision detection and the collision cancellation algorithm. Finally, a relaxation procedure is used to achieve more realistic status. Experimental results show that the behavior of the guide wire or the catheter depends on the defined parameters. The real-time simulation can be achieved. The result shows that the simulation system is effective and promising.
文摘Computational fluid dynamics(CFD) has recently emerged as an effective tool for the investigation of the hydraulic parameters and efficiency of tray towers.The computation domain was established for two types of oriented valves within a tray and meshed into two parts with different grid types and sizes.The volume fraction correlation concerning inter-phase momentum transfer source was fitted based on experimental data,and built in UDF for simulation.The flow pattern of oriented valve tray under different operating conditions was simulated under Eulerian-Eulerian framework with realizable k-ε model.The predicted liquid height from CFD simulation was in good agreement with the results of pressure drop and volume fraction correlations.Meanwhile,the velocity distribution and volume fraction of the two phases were demonstrated and analyzed,which are useful in design and analysis of the column trays.
基金Supported by the Independent Innovation Foundation for National Defense of Huazhong University of Science and Technology(No.01-18-140019)
文摘The effect of a guide vane installed at the elbow on flow-induced noise and vibration is investigated in the range of Reynolds numbers from 1.70×10^5 to 6.81×10^5, and the position of guide vane is determined by publications. The turbulent flow in the piping elbow is simulated with large eddy simulation （LES）. Following this, a hybrid method of combining LES and Lighthill＇s acoustic analogy theory is used to simulate the hydrodynamic noise and sound sources are solved as volume sources in code Actran. In addition, the flow-induced vibration of the piping elbow is investigated based on a fluid-structure interaction （FSI） code. The LES results indicate that the range of vortex zone in the elbow without the guide vane is larger than the case with the guide vane, and the guide vane is effective in reducing flow-induced noise and vibration in the 90° piping elbow at different Reynolds numbers.
基金Projects supported by the National Natural Science Foundation of China (No. 30170550), the Natural Science Foundation of Anhui Provincial Education Department (No. 2005kj398zc) and the Culture Project for "the Tenth Five-year" Learning Leaders of Higher School of Anhui Province, China
文摘To reveal the possible mechanism of silica deposition in higher plants, lignin was isolated from rice straw following a modified method to conduct a simulation experiment in vitro. UV and infrared absorption spectra showed that the substance had the unique characteristics of pure lignin. The presence of silicon in the precipitation was revealed by TEM (transmission electron microscopy) with EDXA (energy dispersive X-ray analysis) device. It was found that in the borax solution where lignin precipi-tation occurred silica-lignin co-precipitation was produced but not in the DMSO solution where lignin was broken into its com-position compounds and did not precipitate. This means that it is macromolecular lignin itself but not its compounds that could induce silica deposition in higher plants.
