As a new type of submarine pipeline, the piggyback pipeline has been gradually adopted in engineering practice to enhance the performance and safety of submarine pipelines. However, limited simulation work and few exp...As a new type of submarine pipeline, the piggyback pipeline has been gradually adopted in engineering practice to enhance the performance and safety of submarine pipelines. However, limited simulation work and few experimental studies have been published on the scour around the piggyback pipeline under steady current. This study numerically and experimentally investigates the local scour of the piggyback pipe under steady current. The influence of prominent factors such as pipe diameter, inflow Reynolds number, and gap between the main and small pipes, on the maximum scour depth have been examined and discussed in detail. Furthermore, one formula to predict the maximum scour depth under the piggyback pipeline has been derived based on the theoretical analysis of scour equilibrium. The feasibility of the proposed formula has been effectively calibrated by both experimental data and numerical results. The findings drawn from this study are instructive in the future design and application of the piggyback pipeline.展开更多
OBJECTIVE: To summarize the experience in modified reconstruction of the hepatic outflow tract during piggyback liver transplantation at our hospital. METHODS: The clinical data on 67 patients undergoing piggyback liv...OBJECTIVE: To summarize the experience in modified reconstruction of the hepatic outflow tract during piggyback liver transplantation at our hospital. METHODS: The clinical data on 67 patients undergoing piggyback liver transplantation with modified hepatic outflow tract reconstruction from January 1999 to October 2002 were analyzed retrospectively. RESULTS: In this group, 7 patients (10. 45%) died perioperatively. Complications included: pulmonary infection (38 patients); multiple organ system failure (10), intraperitoneal bleeding (6), acute respiratory distress syndrome (14), thrombosis of the hepatie artery (1), and bile leakage (1). No hepatic outflow occluded. Two recipients survived for over 3 years, 8 over 2 years, and 19 over a year. CONCLUSION: Modified hepatic outflow reconstruction in piggyback live transplantation may increase the success rate of liver transplantation and decrease technical complications.展开更多
Strong deformed sediments investigated in the Hoh Xil basin may contain detailed records for early Tertiary crustal shortening in northern Tibet (Fig.1A). Sedimentary sequences in the basin consist of the Fenghuoshan ...Strong deformed sediments investigated in the Hoh Xil basin may contain detailed records for early Tertiary crustal shortening in northern Tibet (Fig.1A). Sedimentary sequences in the basin consist of the Fenghuoshan Group, the Yaxicuo Group, and the early Miocene Wudaoliang Group from lower to upper. Magnetostratigraphic research has indicated the Eocene to early Oligocene ages for the Fenghuoshan and Yaxicuo Groups (Liu, et al., 2000). Total 29 lithological sections with 20487 7m thick were measured spread all over the 101000km\+2 Hoh Xil basin, the largest Tertiary sedimentary basin in the hinterland of the Tibetan plateau, to reveal the prototype basin and its evolution processes. They include 17 sections with 14925 3m thick of the Fenghuoshan Group, 8 sections with 4273 5m thick of the Yaxicuo Group, and 4 sections with 1284 9m thick of the Wudaoliang Group.展开更多
A piggyback pipeline consists of two pipes such that the secondary line rides on the main pipe with a fixed distance between two pipes in length.The novel strategy is utilized in offshore areas instead of a single flo...A piggyback pipeline consists of two pipes such that the secondary line rides on the main pipe with a fixed distance between two pipes in length.The novel strategy is utilized in offshore areas instead of a single flow line.In this regard,there are only a handful of experimental and numerical studies investigating the effect of scour below a piggyback pipeline under steady current.Hence,this study focuses on examining the influential factors on scouring due to steady current including the pipe diameter and the gap between pipes through numerical simulations and experimental tests.Accordingly,at the first phase of the research,a single pipe was established and tested in laboratory to compare the results with those of an empirical equation.After finishing experimental verifications,piggyback pipelines were also assembled to study the scouring under steady current conditions.It was concluded that by increasing the gap distance between the pipes,the maximum scour depth decreases;however,an increase in the small pipe’s diameter results in a larger maximum scour depth.Secondly,numerical simulations were carried out using the FLOW-3D software which was found to be a suitable tool for the numerical investigation of this study.Finally,the numerical results have been compared with the corresponding experimental data and a relatively good agreement was achieved between them.展开更多
Hepatic venous outflow obstruction after piggyback liver transplantation is a very rare complication. An unusual mechanism aggravating it is reported. A 33-year-old man with end-stage hepatitis B liver cirrhosis under...Hepatic venous outflow obstruction after piggyback liver transplantation is a very rare complication. An unusual mechanism aggravating it is reported. A 33-year-old man with end-stage hepatitis B liver cirrhosis underwent a piggyback orthotopic liver transplantation using a full-size cadaveric graft. Two months after transplantation, he developed gross ascites refractory to maximal diuretic therapy. Doppler ultrasound showed patent portal and hepatic veins. Serial computed tomography scans revealed a hypoperfused right posterior segment of the liver which subsequently underwent atrophy. Hepatic venography demonstrated a high-grade stenosis with an element of torsion of venous drainage at the anastomosis. The stenosis was successfully treated with repeated percutaneous balloon angioplasty. The patient remained asymptomatic six months afterwards with complete resolution of ascites and peripheral edema. We postulate that liver allograft segmental hypoperfusion and atrophy may aggravate or result in a hepatic venous outflow problem by the mechanism of torsion effect. Percutaneous balloon angioplasty is a safe and effective treatment modality for anastomotic stenosis.展开更多
基金financially supported by the National Key Research and Development Program of China (No.2017YFC1404700)the National Natural Science Foundation of China (Nos.51279189,51239001 and 51509023)the China Scholarship Council
文摘As a new type of submarine pipeline, the piggyback pipeline has been gradually adopted in engineering practice to enhance the performance and safety of submarine pipelines. However, limited simulation work and few experimental studies have been published on the scour around the piggyback pipeline under steady current. This study numerically and experimentally investigates the local scour of the piggyback pipe under steady current. The influence of prominent factors such as pipe diameter, inflow Reynolds number, and gap between the main and small pipes, on the maximum scour depth have been examined and discussed in detail. Furthermore, one formula to predict the maximum scour depth under the piggyback pipeline has been derived based on the theoretical analysis of scour equilibrium. The feasibility of the proposed formula has been effectively calibrated by both experimental data and numerical results. The findings drawn from this study are instructive in the future design and application of the piggyback pipeline.
文摘OBJECTIVE: To summarize the experience in modified reconstruction of the hepatic outflow tract during piggyback liver transplantation at our hospital. METHODS: The clinical data on 67 patients undergoing piggyback liver transplantation with modified hepatic outflow tract reconstruction from January 1999 to October 2002 were analyzed retrospectively. RESULTS: In this group, 7 patients (10. 45%) died perioperatively. Complications included: pulmonary infection (38 patients); multiple organ system failure (10), intraperitoneal bleeding (6), acute respiratory distress syndrome (14), thrombosis of the hepatie artery (1), and bile leakage (1). No hepatic outflow occluded. Two recipients survived for over 3 years, 8 over 2 years, and 19 over a year. CONCLUSION: Modified hepatic outflow reconstruction in piggyback live transplantation may increase the success rate of liver transplantation and decrease technical complications.
文摘Strong deformed sediments investigated in the Hoh Xil basin may contain detailed records for early Tertiary crustal shortening in northern Tibet (Fig.1A). Sedimentary sequences in the basin consist of the Fenghuoshan Group, the Yaxicuo Group, and the early Miocene Wudaoliang Group from lower to upper. Magnetostratigraphic research has indicated the Eocene to early Oligocene ages for the Fenghuoshan and Yaxicuo Groups (Liu, et al., 2000). Total 29 lithological sections with 20487 7m thick were measured spread all over the 101000km\+2 Hoh Xil basin, the largest Tertiary sedimentary basin in the hinterland of the Tibetan plateau, to reveal the prototype basin and its evolution processes. They include 17 sections with 14925 3m thick of the Fenghuoshan Group, 8 sections with 4273 5m thick of the Yaxicuo Group, and 4 sections with 1284 9m thick of the Wudaoliang Group.
文摘A piggyback pipeline consists of two pipes such that the secondary line rides on the main pipe with a fixed distance between two pipes in length.The novel strategy is utilized in offshore areas instead of a single flow line.In this regard,there are only a handful of experimental and numerical studies investigating the effect of scour below a piggyback pipeline under steady current.Hence,this study focuses on examining the influential factors on scouring due to steady current including the pipe diameter and the gap between pipes through numerical simulations and experimental tests.Accordingly,at the first phase of the research,a single pipe was established and tested in laboratory to compare the results with those of an empirical equation.After finishing experimental verifications,piggyback pipelines were also assembled to study the scouring under steady current conditions.It was concluded that by increasing the gap distance between the pipes,the maximum scour depth decreases;however,an increase in the small pipe’s diameter results in a larger maximum scour depth.Secondly,numerical simulations were carried out using the FLOW-3D software which was found to be a suitable tool for the numerical investigation of this study.Finally,the numerical results have been compared with the corresponding experimental data and a relatively good agreement was achieved between them.
文摘Hepatic venous outflow obstruction after piggyback liver transplantation is a very rare complication. An unusual mechanism aggravating it is reported. A 33-year-old man with end-stage hepatitis B liver cirrhosis underwent a piggyback orthotopic liver transplantation using a full-size cadaveric graft. Two months after transplantation, he developed gross ascites refractory to maximal diuretic therapy. Doppler ultrasound showed patent portal and hepatic veins. Serial computed tomography scans revealed a hypoperfused right posterior segment of the liver which subsequently underwent atrophy. Hepatic venography demonstrated a high-grade stenosis with an element of torsion of venous drainage at the anastomosis. The stenosis was successfully treated with repeated percutaneous balloon angioplasty. The patient remained asymptomatic six months afterwards with complete resolution of ascites and peripheral edema. We postulate that liver allograft segmental hypoperfusion and atrophy may aggravate or result in a hepatic venous outflow problem by the mechanism of torsion effect. Percutaneous balloon angioplasty is a safe and effective treatment modality for anastomotic stenosis.
