To investigate the effects of sudden change in wind loads on the running performance of trains on the bridge in crosswinds,a highway-railway one-story bridge was taken as the research object.Aerodynamic coefficients o...To investigate the effects of sudden change in wind loads on the running performance of trains on the bridge in crosswinds,a highway-railway one-story bridge was taken as the research object.Aerodynamic coefficients of the train and the bridge were measured in a series of train-bridge system segment models through wind tunnel tests when two trains passed each other on the bridge and when a train entered and left the wind barrier section of the bridge.Based on the improved SIMPACK and ANSYS rigid-flexible coupling simulation method,a wind-double train-track-bridge system coupled vibration model was established.The dynamic responses of the train were analyzed under the effects of sudden change in wind loads caused by two trains passing each other and a train entering and leaving the wind barrier section of the bridge.The results show that the effects of sudden wind load change caused by the trains passing each other had less effects on the running safety of the leeward-side train than the wind shielding effect caused by the windward-side train in the wind speed range of 10−25 m/s.With the decrease in the porosity of wind barriers,the effects of the sudden wind load change played an increasingly important role in the running safety and comfort of the train.With the increase in wind speed,the lateral response of the train increased obviously because of the effects of sudden wind load change,which affects both the lateral running stability and the comfort of the train.展开更多
In order to reveal combustion characteristics of H_2/air mixture in a micro-combustor with and without bluff body, the effects of inlet velocities, equivalence ratios and bluff body's blockage ratios on the temper...In order to reveal combustion characteristics of H_2/air mixture in a micro-combustor with and without bluff body, the effects of inlet velocities, equivalence ratios and bluff body's blockage ratios on the temperature field, pressure of the combustor wall, combustion efficiency and blow-off limit were investigated. The numerical results indicate that the sudden expansion plate micro combustor with bluff body could enhance the turbulent disturbance of the mixed gas in the combustion chamber and the combustion condition is improved. Moreover, a low-speed and high temperature recirculation region was formed between the sudden expansion step and the bluff body so that the high and uniform wall temperature(>1000 K) could be gotten. As a result, it could strengthen the mixing process, prolong the residence time of gas, control the flame position effectively and widen the operation range by the synergistic effect of the bluff body and steps. When the blockage ratio ranged from 0.3 to 0.6, it could be found that the bluff body could play a stabilizing effect and expand combustion blow burning limit, and combustion efficiency firstly was increased with the inlet velocity and equivalence ratio, and then was decreased.展开更多
Patients developing hemoptysis or pulmonary infiltrates together with glomerulonephritis, particu- larly the rapidly progressive cases, are considered to be pulmonary renal syndrome （PRS）. The occur- rence of PRS, a...Patients developing hemoptysis or pulmonary infiltrates together with glomerulonephritis, particu- larly the rapidly progressive cases, are considered to be pulmonary renal syndrome （PRS）. The occur- rence of PRS, an etiologically rare heterogeneous group of diseases, constitutes a medical emergency associated with a high risk of fatal outcome.展开更多
During the design of pipeline,the determination of local resistant coefficient is often come arcoss.The sudden enlargement local resistant coefficient ξ 1=1-A 1A 2 2 is determined through theory.In the paper,the ...During the design of pipeline,the determination of local resistant coefficient is often come arcoss.The sudden enlargement local resistant coefficient ξ 1=1-A 1A 2 2 is determined through theory.In the paper,the sudden enlargement local resistant coefficient under the conditions of three kinds of A 1A 2 was studied in experiment.In the end ,the result shows that ξ 1 is related not only to two flow cross sections,but also to the velocity.Through experimental research,the relationship between ξ 1,A 1A 2 and V 1 was determined.In a word,the hydraulic calculation of pipeline can be done by taking correspondent ξ 1 ,according to the design velocity V 1 and A 1A 2.展开更多
The size mismatch in an end-to-end vascular anastomosis between the host vessel and the graft may cause flow disturbance and predispose to thrombosis [1].Although a number of techniques have been employed to reduce th...The size mismatch in an end-to-end vascular anastomosis between the host vessel and the graft may cause flow disturbance and predispose to thrombosis [1].Although a number of techniques have been employed to reduce the risk of anastomotic thrombosis due to the size mismatch。展开更多
It is never an easy thing to diagnose heart vascular disease only depending on the unenhanced postmortem computed tomography(PMCT).This article reported a case of sudden natural death after the complaint of anterior c...It is never an easy thing to diagnose heart vascular disease only depending on the unenhanced postmortem computed tomography(PMCT).This article reported a case of sudden natural death after the complaint of anterior chest pain in which coronary artery calcification(CAC) was clearly displayed using PMCT scan.The entire coronary artery system was almost reconstructed via multiplanar reformation(MPR) and volume-rendering reconstruction(VR),and the total calcium score of the coronary arteries was obtained with CaScoring automatic analysis software.The results showed that CAC was conspicuous;the total calcium score was 640.3,considerably higher than 400.The pulmonary ground-glass opacity(GGO) and small amount of fluid both in the subglottic trachea and main bronchi were also found.The imaging results confirmed those of autopsy.In addition,the results concluded that PMCT might serve as an invaluable adjunct to the classic autopsy procedure.展开更多
Introduction Leukem ia is a hem atologic neoplasm characterized by potential infectious and hem orrhagic com plications In adult patients with acute leukem ia,in fection is the most com m on com plication.Imtrcra nial...Introduction Leukem ia is a hem atologic neoplasm characterized by potential infectious and hem orrhagic com plications In adult patients with acute leukem ia,in fection is the most com m on com plication.Imtrcra nial hem orrhage (ICH) is the second most common com plication.H ow ever,ICH has been identified as the m ajor cause of m orbidity and m ortaliity in pa tients with leukem ia[1-6].A num ber of case ceports ascribed the death of leukem ic patients due to hem orrhge of the supratentorial and infratentorial brain,basal ganglia,and cerebellum [2,7-9].However,few cases have reported on brainstem hem orrhage.The current case report involved a young wom an who died of brainstem hem orrhage due to acute leukem ia,discussing the pathophysiologic m echanism underly ing ICH.Futhherm ore,the risk factors were specified,w ith a provision of suggestions to forensic pathologists in handling deaths associated w ith ICH,especially sudden unexpected deaths.展开更多
基金Projects(51822803,51878080,51778073) supported by the National Natural Science Foundation of ChinaProjects(2020JJ3035,2018JJ3538) supported by the Hunan Provincial Natural Science Foundation of China。
文摘To investigate the effects of sudden change in wind loads on the running performance of trains on the bridge in crosswinds,a highway-railway one-story bridge was taken as the research object.Aerodynamic coefficients of the train and the bridge were measured in a series of train-bridge system segment models through wind tunnel tests when two trains passed each other on the bridge and when a train entered and left the wind barrier section of the bridge.Based on the improved SIMPACK and ANSYS rigid-flexible coupling simulation method,a wind-double train-track-bridge system coupled vibration model was established.The dynamic responses of the train were analyzed under the effects of sudden change in wind loads caused by two trains passing each other and a train entering and leaving the wind barrier section of the bridge.The results show that the effects of sudden wind load change caused by the trains passing each other had less effects on the running safety of the leeward-side train than the wind shielding effect caused by the windward-side train in the wind speed range of 10−25 m/s.With the decrease in the porosity of wind barriers,the effects of the sudden wind load change played an increasingly important role in the running safety and comfort of the train.With the increase in wind speed,the lateral response of the train increased obviously because of the effects of sudden wind load change,which affects both the lateral running stability and the comfort of the train.
基金Project(51176045)supported by the National Natural Science Foundation of ChinaProject(201208430262)supported by the National Studying Abroad Foundation of China
文摘In order to reveal combustion characteristics of H_2/air mixture in a micro-combustor with and without bluff body, the effects of inlet velocities, equivalence ratios and bluff body's blockage ratios on the temperature field, pressure of the combustor wall, combustion efficiency and blow-off limit were investigated. The numerical results indicate that the sudden expansion plate micro combustor with bluff body could enhance the turbulent disturbance of the mixed gas in the combustion chamber and the combustion condition is improved. Moreover, a low-speed and high temperature recirculation region was formed between the sudden expansion step and the bluff body so that the high and uniform wall temperature(>1000 K) could be gotten. As a result, it could strengthen the mixing process, prolong the residence time of gas, control the flame position effectively and widen the operation range by the synergistic effect of the bluff body and steps. When the blockage ratio ranged from 0.3 to 0.6, it could be found that the bluff body could play a stabilizing effect and expand combustion blow burning limit, and combustion efficiency firstly was increased with the inlet velocity and equivalence ratio, and then was decreased.
文摘Patients developing hemoptysis or pulmonary infiltrates together with glomerulonephritis, particu- larly the rapidly progressive cases, are considered to be pulmonary renal syndrome （PRS）. The occur- rence of PRS, an etiologically rare heterogeneous group of diseases, constitutes a medical emergency associated with a high risk of fatal outcome.
文摘During the design of pipeline,the determination of local resistant coefficient is often come arcoss.The sudden enlargement local resistant coefficient ξ 1=1-A 1A 2 2 is determined through theory.In the paper,the sudden enlargement local resistant coefficient under the conditions of three kinds of A 1A 2 was studied in experiment.In the end ,the result shows that ξ 1 is related not only to two flow cross sections,but also to the velocity.Through experimental research,the relationship between ξ 1,A 1A 2 and V 1 was determined.In a word,the hydraulic calculation of pipeline can be done by taking correspondent ξ 1 ,according to the design velocity V 1 and A 1A 2.
基金supported by Grants-in-Aid from the National Natural Science Foundation of China No.10632010,30670517
文摘The size mismatch in an end-to-end vascular anastomosis between the host vessel and the graft may cause flow disturbance and predispose to thrombosis [1].Although a number of techniques have been employed to reduce the risk of anastomotic thrombosis due to the size mismatch。
基金This study was funded Natural Science Foundation would like to thank Prof. technical assistance, who Huadong Hospital, Shangh by the Council of National of China （GY2012-1）. We ZHANG Guo-zhen for his works in the CT room of ai, China.
文摘It is never an easy thing to diagnose heart vascular disease only depending on the unenhanced postmortem computed tomography(PMCT).This article reported a case of sudden natural death after the complaint of anterior chest pain in which coronary artery calcification(CAC) was clearly displayed using PMCT scan.The entire coronary artery system was almost reconstructed via multiplanar reformation(MPR) and volume-rendering reconstruction(VR),and the total calcium score of the coronary arteries was obtained with CaScoring automatic analysis software.The results showed that CAC was conspicuous;the total calcium score was 640.3,considerably higher than 400.The pulmonary ground-glass opacity(GGO) and small amount of fluid both in the subglottic trachea and main bronchi were also found.The imaging results confirmed those of autopsy.In addition,the results concluded that PMCT might serve as an invaluable adjunct to the classic autopsy procedure.
基金This study was funded by Natural Science Foundation of China
文摘Introduction Leukem ia is a hem atologic neoplasm characterized by potential infectious and hem orrhagic com plications In adult patients with acute leukem ia,in fection is the most com m on com plication.Imtrcra nial hem orrhage (ICH) is the second most common com plication.H ow ever,ICH has been identified as the m ajor cause of m orbidity and m ortaliity in pa tients with leukem ia[1-6].A num ber of case ceports ascribed the death of leukem ic patients due to hem orrhge of the supratentorial and infratentorial brain,basal ganglia,and cerebellum [2,7-9].However,few cases have reported on brainstem hem orrhage.The current case report involved a young wom an who died of brainstem hem orrhage due to acute leukem ia,discussing the pathophysiologic m echanism underly ing ICH.Futhherm ore,the risk factors were specified,w ith a provision of suggestions to forensic pathologists in handling deaths associated w ith ICH,especially sudden unexpected deaths.
