In order to research segmented diverters for aircraft lightning protection, a transient 2 D multiphysics model based on magnetohydrodynamics theory is proposed to predict the location of the arc plasma discharge and l...In order to research segmented diverters for aircraft lightning protection, a transient 2 D multiphysics model based on magnetohydrodynamics theory is proposed to predict the location of the arc plasma discharge and lightning channel, and to simulate the electrothermal behavior.Based on numerical calculation and preliminary analysis, factors that affect the breakdown voltage of the segmented diverter are discussed. The results show that the voltage increase rate of the voltage source, the width of the air gap between metal segments and the geometry of these segments influence the breakdown voltage of the strip. High-voltage tests of the segmented diverter are performed to reveal air breakdown of the strip and redirect the lightning current.Experimental and numerical results are compared to verify the correctness of the numerical model. The ionization of the air gap between metal segments and the breakdown voltage of the strip calculated by the model are qualitatively consistent with experimental results. The breakdown voltage of the segmented diverter is far lower than the lightning voltage. When a lightning strike occurs, the segmented diverter can be quickly ionized to form a plasma channel which can guide the lightning current well.展开更多
BACKGROUND Hepatocellular carcinoma is an aggressive tumor,and its latency and lack of clinical symptoms mean that most patients are already in the late stage when diagnosed.Large tumor volume and metastasis are the m...BACKGROUND Hepatocellular carcinoma is an aggressive tumor,and its latency and lack of clinical symptoms mean that most patients are already in the late stage when diagnosed.Large tumor volume and metastasis are the main reasons for not attempting surgery.Portal vein embolization and associated liver partition and portal vein ligation for staged hepatectomy are commonly used in clinical practice to increase the volume of remnant liver to allow surgical resection;however,research in this area is currently lacking.CASE SUMMARY A 48-year-old male patient with a history of viral hepatitis B for at least 30 years attended our center with a hepatic space-occupying lesion detected 3 d previously.Enhanced computed tomography scanning of the upper abdomen revealed a large mass in the right lobe of the liver,centered on the right posterior lobe,with the larger section measuring about 14 cm×10 cm×14 cm.He successfully underwent conversion therapy for a large right liver tumor after combined hepatic artery ligation and transcatheter arterial chemoembolization,and finally had an opportunity to undergo right hemi-hepatectomy and cholecystectomy.He remained asymptomatic with no obvious abnormalities on computed tomography scanning review at 2 mo after surgery.CONCLUSION This case highlights new ideas and provides a reference for conversion therapy of large liver tumors.展开更多
基金supported by National Natural Science Foundation of China (No. 51475369)the Natural Science Basic Research Plan in Shaanxi Province of China (No. 2018JM1001)
文摘In order to research segmented diverters for aircraft lightning protection, a transient 2 D multiphysics model based on magnetohydrodynamics theory is proposed to predict the location of the arc plasma discharge and lightning channel, and to simulate the electrothermal behavior.Based on numerical calculation and preliminary analysis, factors that affect the breakdown voltage of the segmented diverter are discussed. The results show that the voltage increase rate of the voltage source, the width of the air gap between metal segments and the geometry of these segments influence the breakdown voltage of the strip. High-voltage tests of the segmented diverter are performed to reveal air breakdown of the strip and redirect the lightning current.Experimental and numerical results are compared to verify the correctness of the numerical model. The ionization of the air gap between metal segments and the breakdown voltage of the strip calculated by the model are qualitatively consistent with experimental results. The breakdown voltage of the segmented diverter is far lower than the lightning voltage. When a lightning strike occurs, the segmented diverter can be quickly ionized to form a plasma channel which can guide the lightning current well.
文摘BACKGROUND Hepatocellular carcinoma is an aggressive tumor,and its latency and lack of clinical symptoms mean that most patients are already in the late stage when diagnosed.Large tumor volume and metastasis are the main reasons for not attempting surgery.Portal vein embolization and associated liver partition and portal vein ligation for staged hepatectomy are commonly used in clinical practice to increase the volume of remnant liver to allow surgical resection;however,research in this area is currently lacking.CASE SUMMARY A 48-year-old male patient with a history of viral hepatitis B for at least 30 years attended our center with a hepatic space-occupying lesion detected 3 d previously.Enhanced computed tomography scanning of the upper abdomen revealed a large mass in the right lobe of the liver,centered on the right posterior lobe,with the larger section measuring about 14 cm×10 cm×14 cm.He successfully underwent conversion therapy for a large right liver tumor after combined hepatic artery ligation and transcatheter arterial chemoembolization,and finally had an opportunity to undergo right hemi-hepatectomy and cholecystectomy.He remained asymptomatic with no obvious abnormalities on computed tomography scanning review at 2 mo after surgery.CONCLUSION This case highlights new ideas and provides a reference for conversion therapy of large liver tumors.
