In order to figure out the cable flexural rigidity influence on suspension bridges,a contrast model experiment is made:a chain cable model with no flexural rigidity and a wire cable model with some flexural rigidity.A...In order to figure out the cable flexural rigidity influence on suspension bridges,a contrast model experiment is made:a chain cable model with no flexural rigidity and a wire cable model with some flexural rigidity.And then,four finite element models of a same long-span suspension bridge with different cable element are set up to be analyzed.Both experimental and numerical simulation results show that,with the increase of the span and the decrease of sag-span ratio,the influence of the cable flexural rigidity is significant.The difference of nodes displacement reaches more than 10 cm in construction analysis,which will bring some trouble to the construction.And the difference of the maximum section edge normal stress may reach 15%,which may have an adverse impact onto the bridge.Therefore,considering the cable flexural rigidity is necessary on some analysis of suspension bridges.展开更多
The effects of rigid vegetation on the turbulence characteristics were experimentally studied in the interior water flume. An ADV was used to determine the three dimensional turbulent velocities in clear water flow wi...The effects of rigid vegetation on the turbulence characteristics were experimentally studied in the interior water flume. An ADV was used to determine the three dimensional turbulent velocities in clear water flow without vegetation, sediment-laden flow without vegetation, sediment-laden flow with submerged vegetation and sediment-laden flow with non-submerged vegetation. By experimental and theoretical analysis, the effects of rigid vegetation on the distribution of averaged velocities, turbulence intensities and Reynolds stress were summarized. In sediment-laden flow with submerged vegetation, the averaged stream wise velocities above the top of vegetation fit well with the log distribution low. The three-dimensional turbulence intensities increase from the bottom until they reach the maximum at the top of the vegetation. The method to calculate the shear velocity with the maximum of the Reynolds stress is recommended. In sediment-laden flow with non-submerged vegetation, the turbulence problems cannot be explained by theory of bed shear flow. The average velocities, turbulence intensities and Reynolds stress approximate uniformly distributed along vertical direction.展开更多
To review the primary experience of video-assisted rigid laser bronchoscopy in the treatment of tracheobronchial tumors.Methods From Sep.2002 to Nov.2004,13 patients (15 procedures) with tracheobronchial tumors were t...To review the primary experience of video-assisted rigid laser bronchoscopy in the treatment of tracheobronchial tumors.Methods From Sep.2002 to Nov.2004,13 patients (15 procedures) with tracheobronchial tumors were treated with video-assisted rigid bronchoscope.Benign tumors with small pedicles were removed directly.For benign tumors with wide pedicles or tumors extending beyond the wall of air-way,total enucleating through thoracotomy were employed.In cases with malignant tumors,stenosis or obstructions were relieved by implantation of stent or cautering with electric argoulaser knife.For malignant but resectable primary tumors of trachea and main bronchi,rigid bronchoscopy might serve as a preparation of radical resection.Results Of the 5 patients with benign tumors,4 received endoscopic total resection and 1 were conversed into thoracotomy.For the 8 malignant cases,3 received stent implantation,2 had palliative ablation 3 got curative resections through thoracotomy.No peri-operative complications or death occurred in this group.Conclusion Total resection of benign tracheobronchial tumors or palliative therapy for tracheobronchial malignant stenosis or preparation of radical resection can be performed safely and efficiently by video-assisted rigid bronchoscopy.5 refs.展开更多
基金Sponsored by Major Research Plan of the National Natural Science Foundation of China (Grant No.90715021)
文摘In order to figure out the cable flexural rigidity influence on suspension bridges,a contrast model experiment is made:a chain cable model with no flexural rigidity and a wire cable model with some flexural rigidity.And then,four finite element models of a same long-span suspension bridge with different cable element are set up to be analyzed.Both experimental and numerical simulation results show that,with the increase of the span and the decrease of sag-span ratio,the influence of the cable flexural rigidity is significant.The difference of nodes displacement reaches more than 10 cm in construction analysis,which will bring some trouble to the construction.And the difference of the maximum section edge normal stress may reach 15%,which may have an adverse impact onto the bridge.Therefore,considering the cable flexural rigidity is necessary on some analysis of suspension bridges.
文摘The effects of rigid vegetation on the turbulence characteristics were experimentally studied in the interior water flume. An ADV was used to determine the three dimensional turbulent velocities in clear water flow without vegetation, sediment-laden flow without vegetation, sediment-laden flow with submerged vegetation and sediment-laden flow with non-submerged vegetation. By experimental and theoretical analysis, the effects of rigid vegetation on the distribution of averaged velocities, turbulence intensities and Reynolds stress were summarized. In sediment-laden flow with submerged vegetation, the averaged stream wise velocities above the top of vegetation fit well with the log distribution low. The three-dimensional turbulence intensities increase from the bottom until they reach the maximum at the top of the vegetation. The method to calculate the shear velocity with the maximum of the Reynolds stress is recommended. In sediment-laden flow with non-submerged vegetation, the turbulence problems cannot be explained by theory of bed shear flow. The average velocities, turbulence intensities and Reynolds stress approximate uniformly distributed along vertical direction.
文摘To review the primary experience of video-assisted rigid laser bronchoscopy in the treatment of tracheobronchial tumors.Methods From Sep.2002 to Nov.2004,13 patients (15 procedures) with tracheobronchial tumors were treated with video-assisted rigid bronchoscope.Benign tumors with small pedicles were removed directly.For benign tumors with wide pedicles or tumors extending beyond the wall of air-way,total enucleating through thoracotomy were employed.In cases with malignant tumors,stenosis or obstructions were relieved by implantation of stent or cautering with electric argoulaser knife.For malignant but resectable primary tumors of trachea and main bronchi,rigid bronchoscopy might serve as a preparation of radical resection.Results Of the 5 patients with benign tumors,4 received endoscopic total resection and 1 were conversed into thoracotomy.For the 8 malignant cases,3 received stent implantation,2 had palliative ablation 3 got curative resections through thoracotomy.No peri-operative complications or death occurred in this group.Conclusion Total resection of benign tracheobronchial tumors or palliative therapy for tracheobronchial malignant stenosis or preparation of radical resection can be performed safely and efficiently by video-assisted rigid bronchoscopy.5 refs.
