The Front Variable Area Bypass Injector(FVABI)is a key to bypass ratio adjustment for a Variable Cycle Engine(VCE).In order to study the role of the FVABI with the Core Driven Fan Stage(CDFS)duct,firstly,the engine by...The Front Variable Area Bypass Injector(FVABI)is a key to bypass ratio adjustment for a Variable Cycle Engine(VCE).In order to study the role of the FVABI with the Core Driven Fan Stage(CDFS)duct,firstly,the engine bypass with the CDFS duct model and the equivalent engine bypass without the CDFS duct model are designed using the concept of a jet boundary line.By comparing the difference between airflow driving forces in the two engine bypass models,the quantitative effects of the injection from the CDFS duct on the mass flow rate of the engine bypass airflow are obtained under different combinations of pressure difference and area ratios.Then,the CDFS duct injection characteristic map is obtained through the typical experiment of the FVABI.Based on this map,the performance model of the FVABI is developed.Finally,the turbofan engine model with the Variable Inlet Guide Vane(VIGV),the First Variable Cycle Engine model(VCE1)with the CDFS duct and without the VIGV,and the Second Variable Cycle Engine model(VCE2)with the CDFS duct and VIGV are built.The gain on the engine bypass ratio adjustment range caused by the injection from the CDFS duct is clarified by comparing the three engine models.It is concluded that the bypass ratio adjustment range of the variable cycle engine with the FVABI is about twice that of the traditional turbofan engine.展开更多
Objective： To investigate whether the method of bridgy duct established between the recipient＇s spleen artery and the donor＇s gastroduodenal artery could inhibit the apoptosis of liver and bile duct cells caused by...Objective： To investigate whether the method of bridgy duct established between the recipient＇s spleen artery and the donor＇s gastroduodenal artery could inhibit the apoptosis of liver and bile duct cells caused by hepatic artery ischemia. Methods： Twenty-four mongrel dogs from Xi＇an area were used to establish simplified models of dog orthotopic liver transplantation and divided into three groups randomly： HAI group （hepatic artery ischemia group）,BBB group（bypassing the blood by a bridgy duct） and control group. After cold perfusion, The samples were collected from liver and bile duct in each group at different time and fixed in glutaraldehyde and 4% polyformaldehyde respectively. At last, the apoptosis of liver and bile duct cells were observed and the apoptotic indexes were calculated. Results： Two hours after cold perfusion, apoptotic phenomenon was common in HAI group, rare in BBB group, while no apoptotic phenomenon was observed in control group. TUNEL staining showed that there was no significant difference in apoptotic index among the three groups immediately after cold perfusion. However, with time going, the apoptotic cells were increased in three groups, and the difference in apoptotic index was significant among three groups （P 〈 0.01 ）. Conclusions： Bridgy duct of hepatic artery can inhibit the apoptosis of liver and bile duct cells caused by HAI significantly.展开更多
The demand of further increasing bypass ratio of aeroengine will lead to low pressure turbines with higher diameter. Therefore, it is necessary to design a duct to guide the hot gas flow which is expelled from the ups...The demand of further increasing bypass ratio of aeroengine will lead to low pressure turbines with higher diameter. Therefore, it is necessary to design a duct to guide the hot gas flow which is expelled from the upstream high pressure (HP) turbine stage to the downstream low pressure (LP) turbine stage. Named by its position, this kind of duct is always called intermediate turbine ducts (ITDs). Due to the pursuit of higher thrust ratio of the aeroengine, this kind of ITDs has to beas short as possible which leads to aggressive (high diffusion) S-shaped ITDs' geometry. In this paper, two different schemes of high diffusion separation-free S-shaped ITDs were studied with the aid of three-dimensional CFD programs. Although these two ITDs have the same area ratios (AR), because of the different duct length, they have totally different area as well as area change rates. With the detailed calculation results, comparisons were made to investigate the underneath physical mechanisms. Additionally, a direct estimation of the ITDs' loss is given at the end of this paper and some ITDs' novel design idea is proposed to initiate some further discussions.展开更多
Over the past decade the ability of endoscopists to access the biliary tree in patients with surgically altered gastroduodenal anatomy has significantly advanced.Much of the progress has occurred as a result of the de...Over the past decade the ability of endoscopists to access the biliary tree in patients with surgically altered gastroduodenal anatomy has significantly advanced.Much of the progress has occurred as a result of the development of better tools to navigate the deep small bowel,such as single-balloon-(SBE),double-balloon-(DBE),and spiral-enteroscopy-assisted endoscopic retrograde cholangiopancreatography(ERCP).However,despite using a cap,accessing the papilla or bile duct using these forward-viewing enteroscopy platforms remains challenging,even in expert hands.In patients with Roux-en-Y gastric bypass(RYGB) anatomy,the excluded stomach is a potential point of access for either a delayed transgastric- or immediate laparoscopyassisted-ERCP approach.However,the parallel advancement of therapeutic endoscopic ultrasound(EUS) also provides alternative approaches through which the biliary system can be accessed and intervened on in patients with surgically altered anatomies.Generally speaking,in patients with short gastro-jejunal "Roux" and bilio-pancreatic limbs,ideally less than 150 cm in length,starting with a(cap-assisted) pushenteroscopy or balloon-enteroscopy approach would offer reasonable diagnostic and therapeutic ERCP suc-cess.When available,short-SBE or short-DBE scopes should be used,as they allow the use of conventional ERCP equipment,are associated with shorter procedure times,and are easier to manipulate.In patients with RYGB who have longer Roux and/or bilio-pancreatic limbs(> 150 cm in total length),or in patients who have failed prior attempts at deep enteroscopy-assisted ERCP,transgastric laparoscopy-assisted-ERCP is associated with higher rates of diagnostic and therapeutic success as compared to deep-enteroscopy-assisted ERCP.Finally,EUS-guided biliary access for antegrade biliary intervention or for rendezvous enteroscopyassisted ERCP is possible.While percutaneous transhepatic biliary drainage and surgical bile duct exploration remain viable alternatives,these methods are not without significant mor展开更多
基金supported by the National Science and Technology Major Project of China (No. J2019-II-00070027)the China Academy of Launch Vehicle Technology Funding (No. CALT2023-07)
文摘The Front Variable Area Bypass Injector(FVABI)is a key to bypass ratio adjustment for a Variable Cycle Engine(VCE).In order to study the role of the FVABI with the Core Driven Fan Stage(CDFS)duct,firstly,the engine bypass with the CDFS duct model and the equivalent engine bypass without the CDFS duct model are designed using the concept of a jet boundary line.By comparing the difference between airflow driving forces in the two engine bypass models,the quantitative effects of the injection from the CDFS duct on the mass flow rate of the engine bypass airflow are obtained under different combinations of pressure difference and area ratios.Then,the CDFS duct injection characteristic map is obtained through the typical experiment of the FVABI.Based on this map,the performance model of the FVABI is developed.Finally,the turbofan engine model with the Variable Inlet Guide Vane(VIGV),the First Variable Cycle Engine model(VCE1)with the CDFS duct and without the VIGV,and the Second Variable Cycle Engine model(VCE2)with the CDFS duct and VIGV are built.The gain on the engine bypass ratio adjustment range caused by the injection from the CDFS duct is clarified by comparing the three engine models.It is concluded that the bypass ratio adjustment range of the variable cycle engine with the FVABI is about twice that of the traditional turbofan engine.
基金National Natural Science Foundation of China(30571765)
文摘Objective： To investigate whether the method of bridgy duct established between the recipient＇s spleen artery and the donor＇s gastroduodenal artery could inhibit the apoptosis of liver and bile duct cells caused by hepatic artery ischemia. Methods： Twenty-four mongrel dogs from Xi＇an area were used to establish simplified models of dog orthotopic liver transplantation and divided into three groups randomly： HAI group （hepatic artery ischemia group）,BBB group（bypassing the blood by a bridgy duct） and control group. After cold perfusion, The samples were collected from liver and bile duct in each group at different time and fixed in glutaraldehyde and 4% polyformaldehyde respectively. At last, the apoptosis of liver and bile duct cells were observed and the apoptotic indexes were calculated. Results： Two hours after cold perfusion, apoptotic phenomenon was common in HAI group, rare in BBB group, while no apoptotic phenomenon was observed in control group. TUNEL staining showed that there was no significant difference in apoptotic index among the three groups immediately after cold perfusion. However, with time going, the apoptotic cells were increased in three groups, and the difference in apoptotic index was significant among three groups （P 〈 0.01 ）. Conclusions： Bridgy duct of hepatic artery can inhibit the apoptosis of liver and bile duct cells caused by HAI significantly.
文摘The demand of further increasing bypass ratio of aeroengine will lead to low pressure turbines with higher diameter. Therefore, it is necessary to design a duct to guide the hot gas flow which is expelled from the upstream high pressure (HP) turbine stage to the downstream low pressure (LP) turbine stage. Named by its position, this kind of duct is always called intermediate turbine ducts (ITDs). Due to the pursuit of higher thrust ratio of the aeroengine, this kind of ITDs has to beas short as possible which leads to aggressive (high diffusion) S-shaped ITDs' geometry. In this paper, two different schemes of high diffusion separation-free S-shaped ITDs were studied with the aid of three-dimensional CFD programs. Although these two ITDs have the same area ratios (AR), because of the different duct length, they have totally different area as well as area change rates. With the detailed calculation results, comparisons were made to investigate the underneath physical mechanisms. Additionally, a direct estimation of the ITDs' loss is given at the end of this paper and some ITDs' novel design idea is proposed to initiate some further discussions.
文摘Over the past decade the ability of endoscopists to access the biliary tree in patients with surgically altered gastroduodenal anatomy has significantly advanced.Much of the progress has occurred as a result of the development of better tools to navigate the deep small bowel,such as single-balloon-(SBE),double-balloon-(DBE),and spiral-enteroscopy-assisted endoscopic retrograde cholangiopancreatography(ERCP).However,despite using a cap,accessing the papilla or bile duct using these forward-viewing enteroscopy platforms remains challenging,even in expert hands.In patients with Roux-en-Y gastric bypass(RYGB) anatomy,the excluded stomach is a potential point of access for either a delayed transgastric- or immediate laparoscopyassisted-ERCP approach.However,the parallel advancement of therapeutic endoscopic ultrasound(EUS) also provides alternative approaches through which the biliary system can be accessed and intervened on in patients with surgically altered anatomies.Generally speaking,in patients with short gastro-jejunal "Roux" and bilio-pancreatic limbs,ideally less than 150 cm in length,starting with a(cap-assisted) pushenteroscopy or balloon-enteroscopy approach would offer reasonable diagnostic and therapeutic ERCP suc-cess.When available,short-SBE or short-DBE scopes should be used,as they allow the use of conventional ERCP equipment,are associated with shorter procedure times,and are easier to manipulate.In patients with RYGB who have longer Roux and/or bilio-pancreatic limbs(> 150 cm in total length),or in patients who have failed prior attempts at deep enteroscopy-assisted ERCP,transgastric laparoscopy-assisted-ERCP is associated with higher rates of diagnostic and therapeutic success as compared to deep-enteroscopy-assisted ERCP.Finally,EUS-guided biliary access for antegrade biliary intervention or for rendezvous enteroscopyassisted ERCP is possible.While percutaneous transhepatic biliary drainage and surgical bile duct exploration remain viable alternatives,these methods are not without significant mor
