Gear assembly errors can lead to the increase of vibration and noise of the system,which affect the stability of system.The influence can be compensated by tooth modification.Firstly,an improved three-dimensional load...Gear assembly errors can lead to the increase of vibration and noise of the system,which affect the stability of system.The influence can be compensated by tooth modification.Firstly,an improved three-dimensional loaded tooth contact analysis(3D-LTCA)method which can consider tooth modification and coupling assembly errors is proposed,and mesh stiffness calculated by proposed method is verified by MASTA software.Secondly,based on neural network,the surrogate model(SM)that maps the relationship between modification parameters and mesh mechanical parameters is established,and its accuracy is verified.Finally,SM is introduced to establish an optimization model with the target of minimizing mesh stiffness variations and obtaining more even load distribution on mesh surface.The results show that even considering training time,the efficiency of gear pair optimization by surrogate model is still much higher than that by LTCA method.After optimization,the mesh stiffness fluctuation of gear pair with coupling assembly error is reduced by 34.10%,and difference in average contact stresses between left and right regions of the mesh surface is reduced by 62.84%.展开更多
Objective To analyze the clinical and angiographic characteristics associated with asymptomatic versus symptomatic restenosis after percutaneous coronary intervention(PCI).Methods One hundred and sixty eight patients ...Objective To analyze the clinical and angiographic characteristics associated with asymptomatic versus symptomatic restenosis after percutaneous coronary intervention(PCI).Methods One hundred and sixty eight patients who underwent percutaneous revascularization and 6 month follow up angiography were recruited from 2001 to 2002, in which Fifty nine patients with angiographic restenosis ( ≥50% diameter stenosis) were analyzed. Multivariate analysis evaluated 24 clinical and angiographic variables, comparing those with and without angina. Results Restenosis occurred in 32 patients with clinical silence (55%) and 27 patients with angina. Male sex ( P =0.03 ), absence of antianginal therapy with nitrates ( P =0.002 ) ,greater reference diameter after the procedure ( P =0.04 ), greater reference diameter at follow up (P=0.01), and less lesion severity at 6 months ( P =0.04 ) were univariate predictors of asymptomatic restenosis. By multivariate analysis, only male, greater reference diameter at follow up, and less lesion severity at 6 months were associated with restenosis without angina.Conclusions Approximately half of patients with angiographic restenosis have no symptoms. The only multivariate predictors of silent restenosis at 6 months were male sex, greater reference diameter at follow up, and less lesion severity on follow up angiography.展开更多
Objective To investigate the clinical characteristics and imaging manifestations of AIDS complicated with disseminated Penicillium marneffei (PM) infection. Methods A total of 12 patients with AIDS complicated with di...Objective To investigate the clinical characteristics and imaging manifestations of AIDS complicated with disseminated Penicillium marneffei (PM) infection. Methods A total of 12 patients with AIDS complicated with disseminated PM infection were collected and the symptoms, signs, laboratory examination results and image manifestations of these patients were analyzed retrospectively. Results (1) The diagnosis of PM infection in all the 12 cases were confirmed by peripheral blood culture. All the 12 cases (100%) had irregular fever (38-41 ) and enlarged lymph nodes, 8 cases (66%) had skin rashes; 8 cases (66%) had hepatomegaly; 9 cases (75%) had splenomegaly while 8 cases (66%) had anemia. (2) Imaging manifestation: Five cases manifested bilateral pulmonary disseminated miliary nodular shadows or lattice signs; 1 case showed enlarged hilar lymph node and 2 cases showed patchy shadow with pleuritis. One case presented sub-pleural curve line shadow at the posterior part of the right lower lung, and adhesion between the intestinal wall and intestinal mesentery in mass form in the abdomen by CT examination. Conclusion Patients suffering from AIDS (CD4 T lymphocytes <50/ u L) with impaired immunity might be susceptible to complication of disseminated PM infection, which presents mainly damage of multiple organs and symptoms such as fever; enlargement of liver, spleen and lymph nodes, as well as specific skin maculopapular rashes. Imaging manifestations in the lungs were revealed as miliary nodular shadows and lattice-like shadows. Intensified abdominal CT might reveal presence of several enlarged postperitoneal lymph nodes and intestinal adhesion in shape of "cakes".展开更多
基金Project(11972112)supported by the National Natural Science Foundation of ChinaProject(N2103024)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(J2019-IV-0018-0086)supported by the National Science and Technology Major Project,China。
文摘Gear assembly errors can lead to the increase of vibration and noise of the system,which affect the stability of system.The influence can be compensated by tooth modification.Firstly,an improved three-dimensional loaded tooth contact analysis(3D-LTCA)method which can consider tooth modification and coupling assembly errors is proposed,and mesh stiffness calculated by proposed method is verified by MASTA software.Secondly,based on neural network,the surrogate model(SM)that maps the relationship between modification parameters and mesh mechanical parameters is established,and its accuracy is verified.Finally,SM is introduced to establish an optimization model with the target of minimizing mesh stiffness variations and obtaining more even load distribution on mesh surface.The results show that even considering training time,the efficiency of gear pair optimization by surrogate model is still much higher than that by LTCA method.After optimization,the mesh stiffness fluctuation of gear pair with coupling assembly error is reduced by 34.10%,and difference in average contact stresses between left and right regions of the mesh surface is reduced by 62.84%.
文摘Objective To analyze the clinical and angiographic characteristics associated with asymptomatic versus symptomatic restenosis after percutaneous coronary intervention(PCI).Methods One hundred and sixty eight patients who underwent percutaneous revascularization and 6 month follow up angiography were recruited from 2001 to 2002, in which Fifty nine patients with angiographic restenosis ( ≥50% diameter stenosis) were analyzed. Multivariate analysis evaluated 24 clinical and angiographic variables, comparing those with and without angina. Results Restenosis occurred in 32 patients with clinical silence (55%) and 27 patients with angina. Male sex ( P =0.03 ), absence of antianginal therapy with nitrates ( P =0.002 ) ,greater reference diameter after the procedure ( P =0.04 ), greater reference diameter at follow up (P=0.01), and less lesion severity at 6 months ( P =0.04 ) were univariate predictors of asymptomatic restenosis. By multivariate analysis, only male, greater reference diameter at follow up, and less lesion severity at 6 months were associated with restenosis without angina.Conclusions Approximately half of patients with angiographic restenosis have no symptoms. The only multivariate predictors of silent restenosis at 6 months were male sex, greater reference diameter at follow up, and less lesion severity on follow up angiography.
基金Supported by the sustentation fund item of WU Jie-ping (2003-86-F)
文摘Objective To investigate the clinical characteristics and imaging manifestations of AIDS complicated with disseminated Penicillium marneffei (PM) infection. Methods A total of 12 patients with AIDS complicated with disseminated PM infection were collected and the symptoms, signs, laboratory examination results and image manifestations of these patients were analyzed retrospectively. Results (1) The diagnosis of PM infection in all the 12 cases were confirmed by peripheral blood culture. All the 12 cases (100%) had irregular fever (38-41 ) and enlarged lymph nodes, 8 cases (66%) had skin rashes; 8 cases (66%) had hepatomegaly; 9 cases (75%) had splenomegaly while 8 cases (66%) had anemia. (2) Imaging manifestation: Five cases manifested bilateral pulmonary disseminated miliary nodular shadows or lattice signs; 1 case showed enlarged hilar lymph node and 2 cases showed patchy shadow with pleuritis. One case presented sub-pleural curve line shadow at the posterior part of the right lower lung, and adhesion between the intestinal wall and intestinal mesentery in mass form in the abdomen by CT examination. Conclusion Patients suffering from AIDS (CD4 T lymphocytes <50/ u L) with impaired immunity might be susceptible to complication of disseminated PM infection, which presents mainly damage of multiple organs and symptoms such as fever; enlargement of liver, spleen and lymph nodes, as well as specific skin maculopapular rashes. Imaging manifestations in the lungs were revealed as miliary nodular shadows and lattice-like shadows. Intensified abdominal CT might reveal presence of several enlarged postperitoneal lymph nodes and intestinal adhesion in shape of "cakes".
