In this paper, a novel direction of arrival(DOA) estimation algorithm using directional antennas in cylindrical conformal arrays(CCAs) is proposed. To eliminate the shadow effect, we divide the CCAs into several subar...In this paper, a novel direction of arrival(DOA) estimation algorithm using directional antennas in cylindrical conformal arrays(CCAs) is proposed. To eliminate the shadow effect, we divide the CCAs into several subarrays to obtain the complete output vector. Considering the anisotropic radiation pattern of a CCA, which cannot be separated from the manifold matrix, an improved interpolation method is investigated to transform the directional subarray into omnidirectional virtual nested arrays without non-orthogonal perturbation on the noise vector. Then, the cross-correlation matrix(CCM) of the subarrays is used to generate the consecutive co-arrays without redundant elements and eliminate the noise vector. Finally, the full-rank equivalent covariance matrix is constructed using the output of co-arrays,and the unitary estimation of the signal parameters via rotational invariance techniques(ESPRIT) is performed on the equivalent covariance matrix to estimate the DOAs with low computational complexity. Numerical simulations verify the superior performance of the proposed algorithm, especially under a low signal-to-noise ratio(SNR) environment.展开更多
MM： To investigate how to reduce the incidence of biliary complications in rat orthotopic liver transplantation. METHODS： A total of 165 male Wistar rats were ran- domly divided into three groups： Group A, orthotro...MM： To investigate how to reduce the incidence of biliary complications in rat orthotopic liver transplantation. METHODS： A total of 165 male Wistar rats were ran- domly divided into three groups： Group A, orthotropic liver transplantation with modified ＂two-cuff＂ technique; Group B, bile duct was cut and reconstructed without transplantation; and Group C, only laparotomy was performed. Based on the approaches used for biliary reconstruction, Group A was divided into two sub-groups： A1 （n = 30）, duct-duct reconstruction, and A2 （n = 30）, duct-duodenum reconstruction. To study the influence of artery reconstruction on bile duct complication, Group B was divided into four sub-groups： B1 （n = 10）, duct-duct reconstruction with hepatic artery ligation, B2 （n = 10）, duct-duct reconstruction without hepatic artery ligation, B3 （n = 10）, duct-duodenum reconstruction with hepatic artery ligation, and B4 （n = 10）, duct-duodenum recon- struction without hepatic artery ligation. The samples were harvested 14 d after operation or at the time when significant biliary complication was found. RESULTS： In Group A, the anhepatic phase was 13.7 ＋ 1.06 min, and cold ischemia time was 50.5 ＋ 8.6 min. There was no significant difference between A1 and A2 in the operation duration. The time for biliary reconstruction was almost the same among all groups. The success rate for transplantation was 98.3% （59/60）. Significant differ- ences were found in the incidence of biliary complications in Groups A （41.7%）, B （27.5%） and C （0%）. A2 was more likely to have biliary complications than A1 （50% vs 33.3%）. B3 had the highest incidence of biliary complica- tions in Group B. CONCLUSION： Biliary complications are almost in- evitable using the classical ＂two cuff＂ techniques, and duct-duodenum reconstruction is not an ideal option in rat orthotopic liver transplantation.展开更多
基金supported by the National Natural Science Foundation of China (NSFC) [grant number. 61871414]。
文摘In this paper, a novel direction of arrival(DOA) estimation algorithm using directional antennas in cylindrical conformal arrays(CCAs) is proposed. To eliminate the shadow effect, we divide the CCAs into several subarrays to obtain the complete output vector. Considering the anisotropic radiation pattern of a CCA, which cannot be separated from the manifold matrix, an improved interpolation method is investigated to transform the directional subarray into omnidirectional virtual nested arrays without non-orthogonal perturbation on the noise vector. Then, the cross-correlation matrix(CCM) of the subarrays is used to generate the consecutive co-arrays without redundant elements and eliminate the noise vector. Finally, the full-rank equivalent covariance matrix is constructed using the output of co-arrays,and the unitary estimation of the signal parameters via rotational invariance techniques(ESPRIT) is performed on the equivalent covariance matrix to estimate the DOAs with low computational complexity. Numerical simulations verify the superior performance of the proposed algorithm, especially under a low signal-to-noise ratio(SNR) environment.
基金Supported by National Natural Science Foundation of China,No.30671987
文摘MM： To investigate how to reduce the incidence of biliary complications in rat orthotopic liver transplantation. METHODS： A total of 165 male Wistar rats were ran- domly divided into three groups： Group A, orthotropic liver transplantation with modified ＂two-cuff＂ technique; Group B, bile duct was cut and reconstructed without transplantation; and Group C, only laparotomy was performed. Based on the approaches used for biliary reconstruction, Group A was divided into two sub-groups： A1 （n = 30）, duct-duct reconstruction, and A2 （n = 30）, duct-duodenum reconstruction. To study the influence of artery reconstruction on bile duct complication, Group B was divided into four sub-groups： B1 （n = 10）, duct-duct reconstruction with hepatic artery ligation, B2 （n = 10）, duct-duct reconstruction without hepatic artery ligation, B3 （n = 10）, duct-duodenum reconstruction with hepatic artery ligation, and B4 （n = 10）, duct-duodenum recon- struction without hepatic artery ligation. The samples were harvested 14 d after operation or at the time when significant biliary complication was found. RESULTS： In Group A, the anhepatic phase was 13.7 ＋ 1.06 min, and cold ischemia time was 50.5 ＋ 8.6 min. There was no significant difference between A1 and A2 in the operation duration. The time for biliary reconstruction was almost the same among all groups. The success rate for transplantation was 98.3% （59/60）. Significant differ- ences were found in the incidence of biliary complications in Groups A （41.7%）, B （27.5%） and C （0%）. A2 was more likely to have biliary complications than A1 （50% vs 33.3%）. B3 had the highest incidence of biliary complica- tions in Group B. CONCLUSION： Biliary complications are almost in- evitable using the classical ＂two cuff＂ techniques, and duct-duodenum reconstruction is not an ideal option in rat orthotopic liver transplantation.
