目的通过观察超声引导肌间沟臂从神经阻滞中注入等浓度不同容量罗哌卡因的效果,以期寻找超声引导下肌间沟臂丛阻滞的最佳容量。方法 150例拟行超声引导肌间沟臂从神经阻滞患者随机分成I、Ⅱ、Ⅲ三组,每组各50例,分别注入0.5%罗哌卡因15 ...目的通过观察超声引导肌间沟臂从神经阻滞中注入等浓度不同容量罗哌卡因的效果,以期寻找超声引导下肌间沟臂丛阻滞的最佳容量。方法 150例拟行超声引导肌间沟臂从神经阻滞患者随机分成I、Ⅱ、Ⅲ三组,每组各50例,分别注入0.5%罗哌卡因15 m L、20 m L、25 m L。观察各组起效时间,维持时间,感觉阻滞效果,肌肉松弛阻滞效果,术中呼吸、血压、心电图动态改变。结果在感觉、肌松阻滞效果及起效时间观察上,I、II、Ⅲ组比较差异无统计学意义。在维持时间方面比较:I组与Ⅱ、Ⅲ组比差异有统计学意义,Ⅱ、Ⅲ组比差异无统计学意义。观察资料表明超过20ml在臂丛阻滞麻醉中并无增强作用。低至15 m L的容量也可产生完善的麻醉效果,但会缩短麻醉维持时间。术中监护中,未发现心律失常及药物不良反应及并发症。结论罗哌卡因在肌间沟臂丛阻滞麻醉中是能较安全使用的局部麻醉药,在超声引导肌间沟臂丛神经阻滞中其最佳使用容量是20 m L。展开更多
The determination of volume fraction of interracial transition zone （ITZ） is very important for investigating the quantitative relationship between the microstructure and macroscopical property of concrete. In this ...The determination of volume fraction of interracial transition zone （ITZ） is very important for investigating the quantitative relationship between the microstructure and macroscopical property of concrete. In this paper, based on Lu and Torquato＇s most nearest surface distribution function, a calculating process of volume fraction of ITZ is given in detail according to the actual sieve curve in concrete. Then, quantitative formulas are put forward to measure the influencing factors on the ｜TZ vol- ume fraction. In order to validate the given model, the volume fractions of ITZ obtained by numerical calculation are compared with those by computer simulation. The results show that the two are in good agreement. The order of the factors influencing the ITZ volume fraction is the ITZ thickness, the volume fraction of aggregate and the maximum aggregate diameter for Fuller gradation in turn. The 1TZ volume fraction obtained from the equal volume fraction （EVF） gradation is always larger than that from the Fuller gradation for a given volume fraction of aggregate.展开更多
The Maximum-entropy Method(MEM)for determining the complete ODF(orientation distribution function),accompanied with the equal-volume partitioning technique for quantitative texture analysis,was first tested in analysi...The Maximum-entropy Method(MEM)for determining the complete ODF(orientation distribution function),accompanied with the equal-volume partitioning technique for quantitative texture analysis,was first tested in analysing the texture of a commercial purity titanium strip.The experimentally measured results indi- cate that the rolling planes of most grains in this sample are parallel to the{1010}and the{1210}with about ~±10°spread while the rolling directions nearly distribute uniformly and their volume fractions are 19.46％ and 18.70％ respectively.Besides,there are still two weaker texture components,(7526)[1544]and (1105)[2311],with 3.24％and 4.17％respectively.展开更多
Uniaxial compressive experiments of ultrafine-grained Al fabricated by equal channel angular pressing(ECAP) method were performed at wide temperature and strain rate range. The influence of temperature on flow stress,...Uniaxial compressive experiments of ultrafine-grained Al fabricated by equal channel angular pressing(ECAP) method were performed at wide temperature and strain rate range. The influence of temperature on flow stress, strain hardening rate and strain rate sensitivity was investigated experimentally. The results show that both the effect of temperature on flow stress and its strain rate sensitivity of ECAPed Al is much larger than those of the coarse-grained Al. The temperature sensitivity of ultrafine-grained Al is comparatively weaker than that of the coarse-grained Al. Based on the experimental results, the apparent activation volume was estimated at different temperatures and strain rates. The forest dislocation interactions is the dominant thermally activated mechanism for ECAPed Al compressed at quasi-static strain rates, while the viscous drag plays an important role at high strain rates.展开更多
Uniform ventilation is important for the safety of long tunnel in underground buildings,it is difficult to install the large size air duct to ensure the centerline of each cross-section of the traditional variable cro...Uniform ventilation is important for the safety of long tunnel in underground buildings,it is difficult to install the large size air duct to ensure the centerline of each cross-section of the traditional variable cross-section ventila-tion system(VCVS)superimposed on the same horizontal axis,which is significant to the ventilation uniformity,energy consumption and installation convenience of the VCVS.On the contrary,each cross-section of the Equal Cross-section Ventilation System(ECVS)has the same horizontal axis,therefore,it is more convenient to manu-facture and install the large size air duct in the underground long tunnel and achieve uniform ventilation.This study proposes an ECVS,using computational fluid dynamics(CFD)numerical simulation analyzed the influences of main duct velocity,aspect ratio,and outlet numbers on uniformity and energy consumption per unit air vol-ume(ECPV).It revealed that when each ventilation equalizer’s valve Angle𝛽is given,uniformity of air supply decreases slightly with an increase in the inlet velocity.When the air supply main duct aspect ratio increases,the outlet velocity standard deviation range is from 0.22 to 0.34.When outlet numbers N=7~12 and𝛽are constant,air supply uniformity and resistance coefficient𝜉also decrease with the decrease of outlet numbers.The outlet number has a significant influence on the uniformity of system air supply,main duct velocity,and aspect ratio are relatively small.ECPV is positively correlated with the main duct velocity and outlet number,and is negatively correlated with aspect ratio.展开更多
Natural hydrocarbon seeps in the marine environment are important contributors to greenhouse gases in the atmosphere. Such gases include methane, which plays a significant role in global carbon cycling and climate cha...Natural hydrocarbon seeps in the marine environment are important contributors to greenhouse gases in the atmosphere. Such gases include methane, which plays a significant role in global carbon cycling and climate change. To accurately quantify the methane flux from hydrocarbon seeps on the seafloor, a specialized in situ and online gas flux measuring(GFM) device was designed to obtain high-resolution time course gas fluxes using the process of equal volume exchange. The device consists of a 1.0-m diameter, 0.9-m tall, inverted conical tent and a GFM instrument that contains a solenoid valve, level transducer, and gas collection chamber. Rising gas bubbles from seeps were measured by laboratory-calibrated GFM instruments attached to the top of the tent. According to the experimental data, the optimal anti-shake time interval was 5 s. The measurement range of the device was 0–15 L min^(-1), and the relative error was ± 1.0%. The device was initially deployed at an active seep site in the Lingtou Promontory seep field in South China Sea. The amount of gas released from a single gas vent was 30.5 m^3 during the measurement period, and the gas flow rate ranged from 22 to 72 Lh^(-1), depending on tidal period, and was strongly negatively correlated with water depth. The measurement results strongly suggest that oceanic tides and swells had a significant forcing effect on gas flux. Low flow rates were associated with high tides and vice versa. The changes in gas volume escaping from the seafloor seeps could be attributed to the hydrostatic pressure induced by water depth. Our findings suggest that in the marine environment, especially in the shallow shelf area, sea level variation may play an important role in controlling methane release into the ocean. Such releases probably also affect atmospheric methane levels.展开更多
文摘目的通过观察超声引导肌间沟臂从神经阻滞中注入等浓度不同容量罗哌卡因的效果,以期寻找超声引导下肌间沟臂丛阻滞的最佳容量。方法 150例拟行超声引导肌间沟臂从神经阻滞患者随机分成I、Ⅱ、Ⅲ三组,每组各50例,分别注入0.5%罗哌卡因15 m L、20 m L、25 m L。观察各组起效时间,维持时间,感觉阻滞效果,肌肉松弛阻滞效果,术中呼吸、血压、心电图动态改变。结果在感觉、肌松阻滞效果及起效时间观察上,I、II、Ⅲ组比较差异无统计学意义。在维持时间方面比较:I组与Ⅱ、Ⅲ组比差异有统计学意义,Ⅱ、Ⅲ组比差异无统计学意义。观察资料表明超过20ml在臂丛阻滞麻醉中并无增强作用。低至15 m L的容量也可产生完善的麻醉效果,但会缩短麻醉维持时间。术中监护中,未发现心律失常及药物不良反应及并发症。结论罗哌卡因在肌间沟臂丛阻滞麻醉中是能较安全使用的局部麻醉药,在超声引导肌间沟臂丛神经阻滞中其最佳使用容量是20 m L。
基金supported by the National Basic Research Program of China ("973" Project) (Grant No. 2009CB623200)the National High-Tech Research and Development Program of China ("863" Project)(Grant No. 2008AA030794)
文摘The determination of volume fraction of interracial transition zone （ITZ） is very important for investigating the quantitative relationship between the microstructure and macroscopical property of concrete. In this paper, based on Lu and Torquato＇s most nearest surface distribution function, a calculating process of volume fraction of ITZ is given in detail according to the actual sieve curve in concrete. Then, quantitative formulas are put forward to measure the influencing factors on the ｜TZ vol- ume fraction. In order to validate the given model, the volume fractions of ITZ obtained by numerical calculation are compared with those by computer simulation. The results show that the two are in good agreement. The order of the factors influencing the ITZ volume fraction is the ITZ thickness, the volume fraction of aggregate and the maximum aggregate diameter for Fuller gradation in turn. The 1TZ volume fraction obtained from the equal volume fraction （EVF） gradation is always larger than that from the Fuller gradation for a given volume fraction of aggregate.
文摘The Maximum-entropy Method(MEM)for determining the complete ODF(orientation distribution function),accompanied with the equal-volume partitioning technique for quantitative texture analysis,was first tested in analysing the texture of a commercial purity titanium strip.The experimentally measured results indi- cate that the rolling planes of most grains in this sample are parallel to the{1010}and the{1210}with about ~±10°spread while the rolling directions nearly distribute uniformly and their volume fractions are 19.46％ and 18.70％ respectively.Besides,there are still two weaker texture components,(7526)[1544]and (1105)[2311],with 3.24％and 4.17％respectively.
基金Projects(11272267,11102168,10932008)supported by the National Natural Science Foundation of ChinaProject(B07050)supported by Northwestern Polytechnical University
文摘Uniaxial compressive experiments of ultrafine-grained Al fabricated by equal channel angular pressing(ECAP) method were performed at wide temperature and strain rate range. The influence of temperature on flow stress, strain hardening rate and strain rate sensitivity was investigated experimentally. The results show that both the effect of temperature on flow stress and its strain rate sensitivity of ECAPed Al is much larger than those of the coarse-grained Al. The temperature sensitivity of ultrafine-grained Al is comparatively weaker than that of the coarse-grained Al. Based on the experimental results, the apparent activation volume was estimated at different temperatures and strain rates. The forest dislocation interactions is the dominant thermally activated mechanism for ECAPed Al compressed at quasi-static strain rates, while the viscous drag plays an important role at high strain rates.
基金This work was supported by Scientific Research Fund of Hunan Provincial Education Department[19A001]Natural Science Foundation of Hunan Province[2019JJ40303]+1 种基金State Key Laboratory of Air-conditioning Equipment and System Energy Conservation[ACSKL2018KT18]Double-First class International Collaboration Fund of Changsha University of Science and Technology[2018IC16].
文摘Uniform ventilation is important for the safety of long tunnel in underground buildings,it is difficult to install the large size air duct to ensure the centerline of each cross-section of the traditional variable cross-section ventila-tion system(VCVS)superimposed on the same horizontal axis,which is significant to the ventilation uniformity,energy consumption and installation convenience of the VCVS.On the contrary,each cross-section of the Equal Cross-section Ventilation System(ECVS)has the same horizontal axis,therefore,it is more convenient to manu-facture and install the large size air duct in the underground long tunnel and achieve uniform ventilation.This study proposes an ECVS,using computational fluid dynamics(CFD)numerical simulation analyzed the influences of main duct velocity,aspect ratio,and outlet numbers on uniformity and energy consumption per unit air vol-ume(ECPV).It revealed that when each ventilation equalizer’s valve Angle𝛽is given,uniformity of air supply decreases slightly with an increase in the inlet velocity.When the air supply main duct aspect ratio increases,the outlet velocity standard deviation range is from 0.22 to 0.34.When outlet numbers N=7~12 and𝛽are constant,air supply uniformity and resistance coefficient𝜉also decrease with the decrease of outlet numbers.The outlet number has a significant influence on the uniformity of system air supply,main duct velocity,and aspect ratio are relatively small.ECPV is positively correlated with the main duct velocity and outlet number,and is negatively correlated with aspect ratio.
基金provided by the National Scientific Foundation of China (Nos. 41676046 and 41306045)the Knowledge Innovation Project of the Chinese Academy of Sciences (Nos. SIDSSE-201208 and SQ201110)+1 种基金the 'Hundred Talents Program' of the Chinese Academy of Sciencesfinancial support from China Scholarship Council
文摘Natural hydrocarbon seeps in the marine environment are important contributors to greenhouse gases in the atmosphere. Such gases include methane, which plays a significant role in global carbon cycling and climate change. To accurately quantify the methane flux from hydrocarbon seeps on the seafloor, a specialized in situ and online gas flux measuring(GFM) device was designed to obtain high-resolution time course gas fluxes using the process of equal volume exchange. The device consists of a 1.0-m diameter, 0.9-m tall, inverted conical tent and a GFM instrument that contains a solenoid valve, level transducer, and gas collection chamber. Rising gas bubbles from seeps were measured by laboratory-calibrated GFM instruments attached to the top of the tent. According to the experimental data, the optimal anti-shake time interval was 5 s. The measurement range of the device was 0–15 L min^(-1), and the relative error was ± 1.0%. The device was initially deployed at an active seep site in the Lingtou Promontory seep field in South China Sea. The amount of gas released from a single gas vent was 30.5 m^3 during the measurement period, and the gas flow rate ranged from 22 to 72 Lh^(-1), depending on tidal period, and was strongly negatively correlated with water depth. The measurement results strongly suggest that oceanic tides and swells had a significant forcing effect on gas flux. Low flow rates were associated with high tides and vice versa. The changes in gas volume escaping from the seafloor seeps could be attributed to the hydrostatic pressure induced by water depth. Our findings suggest that in the marine environment, especially in the shallow shelf area, sea level variation may play an important role in controlling methane release into the ocean. Such releases probably also affect atmospheric methane levels.
