Experiments were conducted to study the generation of air core and its effect on the outflow shape and discharge in a cylindrical water tank with a bottom well-designed outlet. Depending on the stages of the air core ...Experiments were conducted to study the generation of air core and its effect on the outflow shape and discharge in a cylindrical water tank with a bottom well-designed outlet. Depending on the stages of the air core in the tank, the outflow shape can vary from a smooth water jet to a smooth spindle shape with air-core, and to water sprays. The diameter of the nozzle size also has influence on the outflow pattern. The existence of the penetrated air core can dramatically reduce the outflow discharge, with the discharge coefficient decreasing with the nozzle diameter.展开更多
A Rogowski coil was designed to measure partial discharge (PD) signal with low currents and high frequency. The possibilities of obtaining better measurements of PDs were explored by changing the inductance, mutual ...A Rogowski coil was designed to measure partial discharge (PD) signal with low currents and high frequency. The possibilities of obtaining better measurements of PDs were explored by changing the inductance, mutual inductance, resistance, and capacitance of the coil. The designed Rogowski coil was calibrated under square wave voltage and arbitrary sine wave voltage. Then, according to the parameters of the Rogowski coil, the effect of changing some of these variables was simulated using a bode plot. Comparison shows that the simulation results were consistent with the experimental ones. A needle-plate in air gap model was set up and its PD under impulse voltage was measured. The results demonstrate that the Rogowski coil is adapted to measurement of PDs.展开更多
To provide theoretical basis and practical guidance for preparing composite rods of external diameter no larger than 12 mm by directly continuous casting,low melting point materials of lead and tin were selected to pr...To provide theoretical basis and practical guidance for preparing composite rods of external diameter no larger than 12 mm by directly continuous casting,low melting point materials of lead and tin were selected to prepare composite rods of external diameter 12 mm and inner diameter 8 mm with air pressing core filled continuous casting process.The orthogonal tests consisting of three factors and three levels were designed to investigate the parameters of melting lead temperature,continuous casting speed and air pressure that affect the performance of the composite rods.The results show that melting lead temperature is the most important factor that influences the solid/liquid interface location;continuous casting speed is the most important factor that influences the surface quality and lead and tin inter-diffusion amount;air pressure can improve the surface quality obviously and make the rods easily drawn out,but the surface quality cannot get obvious improvement when the air pressure is above 0.03 MPa.The composite rods have excellent surface quality,obvious intermediate layer,even thick clad,and metallurgical bonding interface under the condition of melting lead temperature of 375 °C,continuous casting speed of 10 mm/min,and air pressure of 0.03 MPa.展开更多
Objective To evaluate the effect of intraoperative combined forced-air warming and fluid warming system on patient’s core temperature, blood loss, transfusion demand, extubation time, and incidence of postoperative s...Objective To evaluate the effect of intraoperative combined forced-air warming and fluid warming system on patient’s core temperature, blood loss, transfusion demand, extubation time, and incidence of postoperative shivering. Methods Forty patients with American Society of Anesthesiologists physical status I andⅡ, aged 18-70 years, scheduled for elective abdominal surgery were randomly assigned to receive intraoperative warming from a forced-air blanket and fluid warming system or conventional cotton blanket, 20 in each group. The core temperature was recorded every 20 minutes during the operation, as well as the blood loss, blood transfusion, extubation time, and incidence of postoperative shivering. Results The core temperature at the end of the surgery in the warming group was significantly different from that in the control group (36.4±0.4℃ vs. 35.3±0.5℃, P<0.001). Application of intraoperative warming significantly shortened the time between the end of the surgery and extubation (P<0.01). Postoperative shivering occurred in 30% of the patients in the control group compared to no patient in the warming group (P <0.01). Conclusion Active warming with air-forced blanket and fluid warming system provides sufficient heat to prevent hypothermia during abdominal surgery.展开更多
An ideal current distribution in the air core transformer coils is obtained using variation principle.Climbing mountain method is utilized for optimizing the dimension and position of the real coils.Not only can the r...An ideal current distribution in the air core transformer coils is obtained using variation principle.Climbing mountain method is utilized for optimizing the dimension and position of the real coils.Not only can the requirement of minimizing the stray field in the plasma region be guaranteed,but also integer turns for the coil can be realized.The latter brings a significant convenience to engineering.展开更多
Based on the method of compound and additional conditions under the conditions of the equal temperature rise and the equal potential drop (P.D.) of resistance, the application of design software of dry-type air-core r...Based on the method of compound and additional conditions under the conditions of the equal temperature rise and the equal potential drop (P.D.) of resistance, the application of design software of dry-type air-core reactor is introduced in this thesis. The analytical methods of the inductance are also given. This approach is proved entirely feasible in theory through the simplification with Bartky transformation, and is able to quickly and accurately calculate reactor inductance. This paper presents the analytical methods of the loss of dry-type air-core reactor as well.展开更多
Theδ18O of ice core enclosed gaseous oxygen(δ18Obub)has been widely used for climate reconstruction in polar regions.Yet,less is known about its climatic implication in the mountainous glaciers as the lack of contin...Theδ18O of ice core enclosed gaseous oxygen(δ18Obub)has been widely used for climate reconstruction in polar regions.Yet,less is known about its climatic implication in the mountainous glaciers as the lack of continuous record.Here,we present a long-term,continuousδ18Obub record from the Tanggula glacier in the central Tibetan Plateau(TP).Based on comparisons of its variation with regional climate and glacier changes,we found that there was a good correlation between the variation of theδ18Obub in this alpine ice core and the accumulation and melting of this glacier.The more developed the firn layer on glacier surface,the more positive theδ18Obub.Conversely,the more intense the glacier melting,the more negative theδ18Obub.Combined with the chronology of ice core enclosed gases,the glacier variations since the late Holocene in the central TP were reconstructed.The result showed that there were four accumulation and three deficit periods of glaciers in this region.The strongest glacier accumulation period was 1610-300 B.C.,which corresponds to the Neoglaciation.The most significant melting period was the last 100 years,which corresponds to the recent global warming.The Medieval Warm Period was relatively significant in the central TP.However,during the Little Ice Age,there was no significant glacier accumulation in the central TP,and even short deficit events occurred.Comparisons of the late Holocene glacier variation in the central TP with glacier and climate variations in the TP and the Northern Hemisphere showed that it was closely related to the North Atlantic Oscillation.展开更多
A 70-year history of precipitation δ^18O record has been retrieved using an ice core drilled from a plat portion of the firn area in the Guoqu Glacier (33°34'37.8″ N, 91°10'35.3″ E, 5720 m a.s.l.) on ...A 70-year history of precipitation δ^18O record has been retrieved using an ice core drilled from a plat portion of the firn area in the Guoqu Glacier (33°34'37.8″ N, 91°10'35.3″ E, 5720 m a.s.l.) on Mt. Geladaindong (the source region of Yangtze River) during October and November, 2005. Based on the seasonality of δ^18O records and the significant positive relationships between monsoon/non-monsoon δ^18O values and summer/spring air temperature from the nearby meteorological stations, the history of summer and spring air temperature have been reconstructed for the last 70 years. The results show that both summer and spring air temperature variations present similar trends during the last 70 years. Regression analysis indicates that the slope of the temperature-δ^18O relationship is 1.3℃/‰ for non-monsoon δ^18O values and spring air temperature, and 0.4℃/‰ for monsoon δ^18O values and summer air temperature. Variation of air temperature recorded in the ice core is consistent with that in the Northern Hemisphere (NH), however, the warming trend in the Geladaindong region is more intense than that in the NH, reflecting a higher sensitivity to global warming in the high elevation regions. In addition, warming trend is greater in spring than in summer.展开更多
目的系统评价身上型和身下全身型充气式保温毯维持腹部手术患者围手术期核心体温的有效性,为腹部手术患者选择合适、有效的主动保温方法提供临床依据。方法通过计算机检索PubMed、Cochrane Library、Web of Science、Scopus、Embase、CI...目的系统评价身上型和身下全身型充气式保温毯维持腹部手术患者围手术期核心体温的有效性,为腹部手术患者选择合适、有效的主动保温方法提供临床依据。方法通过计算机检索PubMed、Cochrane Library、Web of Science、Scopus、Embase、CINAHL、中国知网以及万方数据库,收集身上型和身下全身型充气式保温毯对维持腹部手术患者核心体温有效性的随机对照试验,并追溯其参考文献,检索时限均为建库至2023年3月。2位研究者独立进行文献筛选、数据提取和质量评价后,采用Rev Man 5.4软件对纳入文献进行Meta分析。结果最终纳入5项随机对照试验,总样本量为373例患者。Meta分析结果显示,身下全身型充气式保温毯能升高患者术中核心体温[95%CI为0.13(0.02~0.29),P<0.001],降低围术期非计划低体温的发生率[95%CI为0.15(0.03~0.79),P=0.020],并减少术后寒战的发生[95%CI为0.17(0.05~0.63),P=0.008]。结论身下全身型充气式保温毯对维持腹部手术患者围手术期核心体温有效,可降低围术期非计划低体温和寒战的发生风险。展开更多
文摘Experiments were conducted to study the generation of air core and its effect on the outflow shape and discharge in a cylindrical water tank with a bottom well-designed outlet. Depending on the stages of the air core in the tank, the outflow shape can vary from a smooth water jet to a smooth spindle shape with air-core, and to water sprays. The diameter of the nozzle size also has influence on the outflow pattern. The existence of the penetrated air core can dramatically reduce the outflow discharge, with the discharge coefficient decreasing with the nozzle diameter.
基金The National Natural Science Foundation of China (No.50977075)
文摘A Rogowski coil was designed to measure partial discharge (PD) signal with low currents and high frequency. The possibilities of obtaining better measurements of PDs were explored by changing the inductance, mutual inductance, resistance, and capacitance of the coil. The designed Rogowski coil was calibrated under square wave voltage and arbitrary sine wave voltage. Then, according to the parameters of the Rogowski coil, the effect of changing some of these variables was simulated using a bode plot. Comparison shows that the simulation results were consistent with the experimental ones. A needle-plate in air gap model was set up and its PD under impulse voltage was measured. The results demonstrate that the Rogowski coil is adapted to measurement of PDs.
基金Project(2009AA03Z532) supported by the National High Technology Research and Development Program of ChinaProject(50774009) supported by the National Natural Science Foundation of China
文摘To provide theoretical basis and practical guidance for preparing composite rods of external diameter no larger than 12 mm by directly continuous casting,low melting point materials of lead and tin were selected to prepare composite rods of external diameter 12 mm and inner diameter 8 mm with air pressing core filled continuous casting process.The orthogonal tests consisting of three factors and three levels were designed to investigate the parameters of melting lead temperature,continuous casting speed and air pressure that affect the performance of the composite rods.The results show that melting lead temperature is the most important factor that influences the solid/liquid interface location;continuous casting speed is the most important factor that influences the surface quality and lead and tin inter-diffusion amount;air pressure can improve the surface quality obviously and make the rods easily drawn out,but the surface quality cannot get obvious improvement when the air pressure is above 0.03 MPa.The composite rods have excellent surface quality,obvious intermediate layer,even thick clad,and metallurgical bonding interface under the condition of melting lead temperature of 375 °C,continuous casting speed of 10 mm/min,and air pressure of 0.03 MPa.
文摘Objective To evaluate the effect of intraoperative combined forced-air warming and fluid warming system on patient’s core temperature, blood loss, transfusion demand, extubation time, and incidence of postoperative shivering. Methods Forty patients with American Society of Anesthesiologists physical status I andⅡ, aged 18-70 years, scheduled for elective abdominal surgery were randomly assigned to receive intraoperative warming from a forced-air blanket and fluid warming system or conventional cotton blanket, 20 in each group. The core temperature was recorded every 20 minutes during the operation, as well as the blood loss, blood transfusion, extubation time, and incidence of postoperative shivering. Results The core temperature at the end of the surgery in the warming group was significantly different from that in the control group (36.4±0.4℃ vs. 35.3±0.5℃, P<0.001). Application of intraoperative warming significantly shortened the time between the end of the surgery and extubation (P<0.01). Postoperative shivering occurred in 30% of the patients in the control group compared to no patient in the warming group (P <0.01). Conclusion Active warming with air-forced blanket and fluid warming system provides sufficient heat to prevent hypothermia during abdominal surgery.
文摘An ideal current distribution in the air core transformer coils is obtained using variation principle.Climbing mountain method is utilized for optimizing the dimension and position of the real coils.Not only can the requirement of minimizing the stray field in the plasma region be guaranteed,but also integer turns for the coil can be realized.The latter brings a significant convenience to engineering.
文摘Based on the method of compound and additional conditions under the conditions of the equal temperature rise and the equal potential drop (P.D.) of resistance, the application of design software of dry-type air-core reactor is introduced in this thesis. The analytical methods of the inductance are also given. This approach is proved entirely feasible in theory through the simplification with Bartky transformation, and is able to quickly and accurately calculate reactor inductance. This paper presents the analytical methods of the loss of dry-type air-core reactor as well.
基金supported by the National Natural Science Foundation of China(Grant No.42271312,41201058)the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDA20070102)+1 种基金the National Key R&D Program of China(Grant No.2018YFB1307504)the Science and Technology Program of Tibet Autonomous Region of China(Grant No.XZ202101ZD0014G).
文摘Theδ18O of ice core enclosed gaseous oxygen(δ18Obub)has been widely used for climate reconstruction in polar regions.Yet,less is known about its climatic implication in the mountainous glaciers as the lack of continuous record.Here,we present a long-term,continuousδ18Obub record from the Tanggula glacier in the central Tibetan Plateau(TP).Based on comparisons of its variation with regional climate and glacier changes,we found that there was a good correlation between the variation of theδ18Obub in this alpine ice core and the accumulation and melting of this glacier.The more developed the firn layer on glacier surface,the more positive theδ18Obub.Conversely,the more intense the glacier melting,the more negative theδ18Obub.Combined with the chronology of ice core enclosed gases,the glacier variations since the late Holocene in the central TP were reconstructed.The result showed that there were four accumulation and three deficit periods of glaciers in this region.The strongest glacier accumulation period was 1610-300 B.C.,which corresponds to the Neoglaciation.The most significant melting period was the last 100 years,which corresponds to the recent global warming.The Medieval Warm Period was relatively significant in the central TP.However,during the Little Ice Age,there was no significant glacier accumulation in the central TP,and even short deficit events occurred.Comparisons of the late Holocene glacier variation in the central TP with glacier and climate variations in the TP and the Northern Hemisphere showed that it was closely related to the North Atlantic Oscillation.
基金National Natural Science Foundation of China, No.40401054 National 973 Program of China, No. 2005CB422004+1 种基金 CAS Hundred Talents Program Knowledge Innovation Program of CAS, No. KZCX3-SW-339/334
文摘A 70-year history of precipitation δ^18O record has been retrieved using an ice core drilled from a plat portion of the firn area in the Guoqu Glacier (33°34'37.8″ N, 91°10'35.3″ E, 5720 m a.s.l.) on Mt. Geladaindong (the source region of Yangtze River) during October and November, 2005. Based on the seasonality of δ^18O records and the significant positive relationships between monsoon/non-monsoon δ^18O values and summer/spring air temperature from the nearby meteorological stations, the history of summer and spring air temperature have been reconstructed for the last 70 years. The results show that both summer and spring air temperature variations present similar trends during the last 70 years. Regression analysis indicates that the slope of the temperature-δ^18O relationship is 1.3℃/‰ for non-monsoon δ^18O values and spring air temperature, and 0.4℃/‰ for monsoon δ^18O values and summer air temperature. Variation of air temperature recorded in the ice core is consistent with that in the Northern Hemisphere (NH), however, the warming trend in the Geladaindong region is more intense than that in the NH, reflecting a higher sensitivity to global warming in the high elevation regions. In addition, warming trend is greater in spring than in summer.
文摘目的系统评价身上型和身下全身型充气式保温毯维持腹部手术患者围手术期核心体温的有效性,为腹部手术患者选择合适、有效的主动保温方法提供临床依据。方法通过计算机检索PubMed、Cochrane Library、Web of Science、Scopus、Embase、CINAHL、中国知网以及万方数据库,收集身上型和身下全身型充气式保温毯对维持腹部手术患者核心体温有效性的随机对照试验,并追溯其参考文献,检索时限均为建库至2023年3月。2位研究者独立进行文献筛选、数据提取和质量评价后,采用Rev Man 5.4软件对纳入文献进行Meta分析。结果最终纳入5项随机对照试验,总样本量为373例患者。Meta分析结果显示,身下全身型充气式保温毯能升高患者术中核心体温[95%CI为0.13(0.02~0.29),P<0.001],降低围术期非计划低体温的发生率[95%CI为0.15(0.03~0.79),P=0.020],并减少术后寒战的发生[95%CI为0.17(0.05~0.63),P=0.008]。结论身下全身型充气式保温毯对维持腹部手术患者围手术期核心体温有效,可降低围术期非计划低体温和寒战的发生风险。