针对超导电力系统中超导电缆和超导储能线圈测试需要模拟短路冲击大电流的试验需求,提出了基于脉冲电容器的高压振荡发生器设计方案并对电路进行了理论分析和电路仿真,着重分析了回路电阻对振荡电流持续时间的影响。仿真结果与理论分析...针对超导电力系统中超导电缆和超导储能线圈测试需要模拟短路冲击大电流的试验需求,提出了基于脉冲电容器的高压振荡发生器设计方案并对电路进行了理论分析和电路仿真,着重分析了回路电阻对振荡电流持续时间的影响。仿真结果与理论分析结果相吻合,该结果表明:所设计的高压振荡发生器可以实现25 k A的峰值电流输出,衰减时间可达1 s,能够满足当前超导电力电缆或超导储能线圈冲击大电流试验的需要。展开更多
Objective To evaluate the effects of ultrasound-guided transversus abdominis plane(TAP) block on postoperative analgesia and early recovery in patients undergoing retroperitoneoscopic urologic surgeries.Methods This w...Objective To evaluate the effects of ultrasound-guided transversus abdominis plane(TAP) block on postoperative analgesia and early recovery in patients undergoing retroperitoneoscopic urologic surgeries.Methods This was a randomized,controlled,double-blinded trial.Eligible patients scheduled for retroperitoneoscopic urologic surgeries were randomly assigned to two groups.Group TAP received ultrasound-guided TAP block with 0.5% ropivacaine 20 ml at 30 minutes before surgery,and Group C received TAP sham block with normal saline.All patients received retroperitoneoscopic urologic surgeries under general anesthesia.The primary outcome was the severity of pain after surgery.Secondary outcomes included opioids consumption,analgesics,postoperative nausea and vomiting,time to Foley catheter removal and to passage of flatus,length of post-anesthesia care unit stay and hospital stay.Results Eighty patients completed the study,forty cases in each group.Compared to the Group C,the Group TAP had lower visual analogue scale pain scores within two postoperative days(all P<0.05).They also had less consumption of intraoperative fentanyl(2.0±0.5 vs. 3.8±0.7 μg/kg,P<0.05),reduced incidence of postoperative rescue analgesic usage(12.5% vs. 45.0%,P<0.05),and lower incidence of postoperative nausea and vomiting within postoperative 48 hours(12.5% vs. 25.0%,P<0.05) when compared to the Group C.In addition,Group TAP had a shortened post-anesthesia care unit stay(25±8 vs. 49±12 minutes,P<0.05),and a greater proportion of patients discharged within postoperative three days(57.5% vs. 35.0%,P<0.05).Conclusion Preoperative ultrasound-guided TAP block is an effective technique to improve postoperative analgesia and early recovery in patients undergoing retroperitoneoscopic urologic surgeries.展开更多
By making use of the U（1） gauge potential decomposition theory and the Ф-mapping topological current theory, we investigate the Schroedinger-Chern-Simons model in the thin-film superconductor system and obtain an e...By making use of the U（1） gauge potential decomposition theory and the Ф-mapping topological current theory, we investigate the Schroedinger-Chern-Simons model in the thin-film superconductor system and obtain an exact Bogomolny self-dual equation with a topological term. It is revealed that there exist self-dual vortices in the system. We study the inner topological structure of the self-dual vortices and show that their topological charges are topologically quantized and labeled by Hopf indices and Brouwer degrees. Furthermore, the vortices are found generating or annihilating at the limit points and encountering, splitting or merging at the bifurcation points of the vector field Ф.展开更多
An ultrasonic-guided wave(UGW) is a very promising tool in the field of structural health monitoring and non-destructive test.Numerical analysis was used to simulate the propagation in the rebar and explore the charac...An ultrasonic-guided wave(UGW) is a very promising tool in the field of structural health monitoring and non-destructive test.Numerical analysis was used to simulate the propagation in the rebar and explore the characteristics of UGW in the steel rebar waveguide.Two-dimensional fast Fourier transform was used to process the numerical results and to evaluate the damage.Subsequently,different UGW test influence factors were investigated.The results clearly showed that both the group velocity and the amplitude of longitudinal modes were not very sensitive to stress and temperature variations.However,the received UGW signal energy decreased with the increasing concrete strength.Finally,the interface condition between the concrete and the rebar was investigated.Time-domain and frequency-domain analyses were used to process the received signals.Different interface delamination lengths of the UGW energy attenuation were analyzed and a relationship was obtained.This study successfully proved that UGW is an effective tool in the non-destructive test of reinforced concrete interface delamination.展开更多
文摘针对超导电力系统中超导电缆和超导储能线圈测试需要模拟短路冲击大电流的试验需求,提出了基于脉冲电容器的高压振荡发生器设计方案并对电路进行了理论分析和电路仿真,着重分析了回路电阻对振荡电流持续时间的影响。仿真结果与理论分析结果相吻合,该结果表明:所设计的高压振荡发生器可以实现25 k A的峰值电流输出,衰减时间可达1 s,能够满足当前超导电力电缆或超导储能线圈冲击大电流试验的需要。
文摘Objective To evaluate the effects of ultrasound-guided transversus abdominis plane(TAP) block on postoperative analgesia and early recovery in patients undergoing retroperitoneoscopic urologic surgeries.Methods This was a randomized,controlled,double-blinded trial.Eligible patients scheduled for retroperitoneoscopic urologic surgeries were randomly assigned to two groups.Group TAP received ultrasound-guided TAP block with 0.5% ropivacaine 20 ml at 30 minutes before surgery,and Group C received TAP sham block with normal saline.All patients received retroperitoneoscopic urologic surgeries under general anesthesia.The primary outcome was the severity of pain after surgery.Secondary outcomes included opioids consumption,analgesics,postoperative nausea and vomiting,time to Foley catheter removal and to passage of flatus,length of post-anesthesia care unit stay and hospital stay.Results Eighty patients completed the study,forty cases in each group.Compared to the Group C,the Group TAP had lower visual analogue scale pain scores within two postoperative days(all P<0.05).They also had less consumption of intraoperative fentanyl(2.0±0.5 vs. 3.8±0.7 μg/kg,P<0.05),reduced incidence of postoperative rescue analgesic usage(12.5% vs. 45.0%,P<0.05),and lower incidence of postoperative nausea and vomiting within postoperative 48 hours(12.5% vs. 25.0%,P<0.05) when compared to the Group C.In addition,Group TAP had a shortened post-anesthesia care unit stay(25±8 vs. 49±12 minutes,P<0.05),and a greater proportion of patients discharged within postoperative three days(57.5% vs. 35.0%,P<0.05).Conclusion Preoperative ultrasound-guided TAP block is an effective technique to improve postoperative analgesia and early recovery in patients undergoing retroperitoneoscopic urologic surgeries.
文摘By making use of the U（1） gauge potential decomposition theory and the Ф-mapping topological current theory, we investigate the Schroedinger-Chern-Simons model in the thin-film superconductor system and obtain an exact Bogomolny self-dual equation with a topological term. It is revealed that there exist self-dual vortices in the system. We study the inner topological structure of the self-dual vortices and show that their topological charges are topologically quantized and labeled by Hopf indices and Brouwer degrees. Furthermore, the vortices are found generating or annihilating at the limit points and encountering, splitting or merging at the bifurcation points of the vector field Ф.
基金supported by the National Natural Science Foundation of China (Grant No. 50808030)the Doctoral Fund of Ministry of Education of China (Grant No. 200801411102)+1 种基金Science and Technology Support Program of China (Grant No. 2011BAK02B04)the Fundamental Research Funds for the Central Universities (Grant No. DUT12LK12)
文摘An ultrasonic-guided wave(UGW) is a very promising tool in the field of structural health monitoring and non-destructive test.Numerical analysis was used to simulate the propagation in the rebar and explore the characteristics of UGW in the steel rebar waveguide.Two-dimensional fast Fourier transform was used to process the numerical results and to evaluate the damage.Subsequently,different UGW test influence factors were investigated.The results clearly showed that both the group velocity and the amplitude of longitudinal modes were not very sensitive to stress and temperature variations.However,the received UGW signal energy decreased with the increasing concrete strength.Finally,the interface condition between the concrete and the rebar was investigated.Time-domain and frequency-domain analyses were used to process the received signals.Different interface delamination lengths of the UGW energy attenuation were analyzed and a relationship was obtained.This study successfully proved that UGW is an effective tool in the non-destructive test of reinforced concrete interface delamination.
