The technology of pantograph sinking in the cavity is generally adopted in the new generation of high-speed trains in China for aerodynamic noise reduction in this region. This study takes a high-speed train with a 4-...The technology of pantograph sinking in the cavity is generally adopted in the new generation of high-speed trains in China for aerodynamic noise reduction in this region. This study takes a high-speed train with a 4-car formation and a pantograph as the research object and compares the aerodynamic acoustic performance of two scale models, 1/8 and 1/1, using large eddy simulation and Ffowcs Williams–Hawkings integral equation. It is found that there is no direct scale similarity between their aeroacoustic performance. The 1/1 model airflow is separated at the leading edge of the panhead and reattached to the panhead, and its vortex shedding Strouhal number(St) is 0.17. However, the 1/8 model airflow is separated directly at the leading edge of the panhead, and its St is 0.13. The cavity's vortex shedding frequency is in agreement with that calculated by the Rooster empirical formula. The two scale models exhibit some similar characteristics in distribution of sound source energy, but the energy distribution of the 1/8 model is more concentrated in the middle and lower regions. The contribution rates of their middle and lower regions to the radiated noise in the two models are 27.3% and 87.2%, respectively. The peak frequencies of the radiated noise from the 1/1 model are 307 and 571 Hz. The 307 Hz is consistent with the frequency of panhead vortex shedding, and the 571 Hz is more likely to be the result of the superposition of various components. In contrast, the peak frequencies of the radiated noise from the 1/8 scale model are 280 and 1970 Hz. The 280 Hz comes from the shear layer oscillation between the cavity and the bottom frame, and the 1970 Hz is close to the frequency at which the panhead vortex sheds. This shows that the scaled model results need to be corrected before applying to the full-scale model.展开更多
Objective:To analyze the application value of Elouzmab in patients with acute coronary syndrome(AcS)after percutaneous coronary intervention(PCI),so as to lay a foundation for the follow-up treatment.Merthods:84 ACS p...Objective:To analyze the application value of Elouzmab in patients with acute coronary syndrome(AcS)after percutaneous coronary intervention(PCI),so as to lay a foundation for the follow-up treatment.Merthods:84 ACS patients who underwent PCI inour hospital from December 1,2018 to December 1,2019 were selected and divided into control group(n=42)and study group(n=42)according to the random number table.The control group was treated with statins,and the study group was treated with alloxan combined therapy.The changes of blood lipid index,quality of life score,adverse cardiovascular and cerebrovascular events and adverse reactions were compared before and after treatment.Results:There was no significant difference in TCHO,TG,HDL-C and LDL-Cbetween the two groups before treatment(P>0.05);After treatment,the levels of TCHO,TG,HDL-Cand LDL-C in the study group were significantly lower than those in the control group(P<0.05);There was no significant difference im the scores of WHOQOL BREF before treatment(P>0.05);After treatment,the WHOQOL-BREF scores of the two groups were improved,and the study group was significantly higher than the control group(P<0.05);The incidence of adverse cardiovascular and cerebrovascular events and adverse reactions in the study group was lower than that in the control group,but the difference was not statistically sigmificant(P>0.05).Conclusion:After percutaneous coronary intervention in patients with acute coronary syndrome,the use of Elojumab can effectively reduice the blood lipid index,improve the quality df patients and reduce the incidence of adverse cardiovascular and cerebrovascular events and adverse reactions,which can be effectively promoted in clinical practice.展开更多
基金supported by the National Natural Science Foundation of China (No. 52272363)the Key Laboratory of Aerodynamic Noise Control (No. ANCL20200302),Aid Program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province。
文摘The technology of pantograph sinking in the cavity is generally adopted in the new generation of high-speed trains in China for aerodynamic noise reduction in this region. This study takes a high-speed train with a 4-car formation and a pantograph as the research object and compares the aerodynamic acoustic performance of two scale models, 1/8 and 1/1, using large eddy simulation and Ffowcs Williams–Hawkings integral equation. It is found that there is no direct scale similarity between their aeroacoustic performance. The 1/1 model airflow is separated at the leading edge of the panhead and reattached to the panhead, and its vortex shedding Strouhal number(St) is 0.17. However, the 1/8 model airflow is separated directly at the leading edge of the panhead, and its St is 0.13. The cavity's vortex shedding frequency is in agreement with that calculated by the Rooster empirical formula. The two scale models exhibit some similar characteristics in distribution of sound source energy, but the energy distribution of the 1/8 model is more concentrated in the middle and lower regions. The contribution rates of their middle and lower regions to the radiated noise in the two models are 27.3% and 87.2%, respectively. The peak frequencies of the radiated noise from the 1/1 model are 307 and 571 Hz. The 307 Hz is consistent with the frequency of panhead vortex shedding, and the 571 Hz is more likely to be the result of the superposition of various components. In contrast, the peak frequencies of the radiated noise from the 1/8 scale model are 280 and 1970 Hz. The 280 Hz comes from the shear layer oscillation between the cavity and the bottom frame, and the 1970 Hz is close to the frequency at which the panhead vortex sheds. This shows that the scaled model results need to be corrected before applying to the full-scale model.
文摘Objective:To analyze the application value of Elouzmab in patients with acute coronary syndrome(AcS)after percutaneous coronary intervention(PCI),so as to lay a foundation for the follow-up treatment.Merthods:84 ACS patients who underwent PCI inour hospital from December 1,2018 to December 1,2019 were selected and divided into control group(n=42)and study group(n=42)according to the random number table.The control group was treated with statins,and the study group was treated with alloxan combined therapy.The changes of blood lipid index,quality of life score,adverse cardiovascular and cerebrovascular events and adverse reactions were compared before and after treatment.Results:There was no significant difference in TCHO,TG,HDL-C and LDL-Cbetween the two groups before treatment(P>0.05);After treatment,the levels of TCHO,TG,HDL-Cand LDL-C in the study group were significantly lower than those in the control group(P<0.05);There was no significant difference im the scores of WHOQOL BREF before treatment(P>0.05);After treatment,the WHOQOL-BREF scores of the two groups were improved,and the study group was significantly higher than the control group(P<0.05);The incidence of adverse cardiovascular and cerebrovascular events and adverse reactions in the study group was lower than that in the control group,but the difference was not statistically sigmificant(P>0.05).Conclusion:After percutaneous coronary intervention in patients with acute coronary syndrome,the use of Elojumab can effectively reduice the blood lipid index,improve the quality df patients and reduce the incidence of adverse cardiovascular and cerebrovascular events and adverse reactions,which can be effectively promoted in clinical practice.
