The temperature field and flow field were analyzed to solve the problems of unstable penetration and poor forming quality,which always happen in asymmetric fillet welding. In order to explore the effect of the welding...The temperature field and flow field were analyzed to solve the problems of unstable penetration and poor forming quality,which always happen in asymmetric fillet welding. In order to explore the effect of the welding parameters on welding and improve the quality of forming,a three-dimensional mathematical model of asymmetric fillet welding was established by using the finite element software COMSOL and the coupling equation. The model was considered about the surface tension gradient,the electromagnetic force,gravity and the effect of temperature,radiation and convection heat on physical properties of the material. The flow field and the growth pattern of the weld pool were analyzed,and the weld pool geometry under different welding currents was compared. The results show that,the thin metal was preferentially penetrated,and with the welding process the weld width expanded until the weld beam was fullpenetration. The heat affected zone was got from weld experiments,its shape and size agreed well with the simulation results,which verifies the validity of the theoretical analysis.展开更多
目的:探讨梧桐护理模式下父母陪伴麻醉诱导(parent presence at the induction of anesthesia,PPIA)对行肝穿刺活检术的肝移植状态患儿麻醉诱导期合作度及苏醒期谵妄(Emergence Delirium,ED)的影响。方法:采用随机数字表法,将2021年9月...目的:探讨梧桐护理模式下父母陪伴麻醉诱导(parent presence at the induction of anesthesia,PPIA)对行肝穿刺活检术的肝移植状态患儿麻醉诱导期合作度及苏醒期谵妄(Emergence Delirium,ED)的影响。方法:采用随机数字表法,将2021年9月至2022年3月在全身麻醉下进行肝穿刺活检术的肝移植状态患儿124例分为对照组和观察组各62例。对照组给予常规护理模式下父母陪伴麻醉诱导,观察组行梧桐护理模式下父母陪伴麻醉诱导。比较两组患儿在麻醉诱导时、苏醒时、术后1 h的平均动脉压、心率变化。采用麻醉诱导期合作程度量表(Induction Checklist Compliance,ICC)比较两组患儿麻醉诱导时合作程度,采用苏醒期谵妄量表(Pediatric Anesthesia Emergence Delirium scale,PAED)比较两组患儿苏醒时、术后1 h、术后6 h、术后12 h谵妄评分及谵妄发生率。结果:两组患儿各时间点平均动脉压、心率组间比较差异无统计学意义(P>0.05);观察组患儿诱导时ICC评分低于对照组,苏醒时及术后1 h PAED评分均低于对照组,差异有统计学意义(P<0.05);两组患儿术后6 h、12 h PAED评分比较差异无统计学意义(P>0.05);观察组总体谵妄发生率低于对照组,差异有统计学意义(P<0.05)。结论:梧桐护理模式下父母陪伴麻醉诱导可提高肝移植后肝穿刺活检患儿麻醉诱导期合作程度,降低苏醒期谵妄发生率,对于加速患儿康复,提高患儿围手术期安全具有积极意义。展开更多
Grassland degradation can alter the structure and function of ecosystem and soil seed bank.Therefore,estimating the role of soil seed bank in vegetation regeneration of degraded grasslands is crucial.We selected grass...Grassland degradation can alter the structure and function of ecosystem and soil seed bank.Therefore,estimating the role of soil seed bank in vegetation regeneration of degraded grasslands is crucial.We selected grasslands with three levels of degradation,namely non-degraded(ND),mildly degraded(MD),and heavily degraded(HD)to analyze the effect of grassland degradation on soil seed bank,as well as the role of soil seed bank on vegetation regeneration of the alpine grasslands,China.Soil samples from each level were collected in May,before seedling emergence,in August,after completion of transient seed bank germination,and in December,after seed dispersal,to determine the seed density and species composition through germination experiment.Result showed that a total of 35 plant species was identified,including 15 species observed in both soil seed bank and above-ground vegetation.A total of 19,15,and 14 species of soil seed bank were identified in December,May,and August,respectively.The most abundant species in soil seed bank were Compositae(5 species),followed by Poaceae(4 species),and Cyperaceae(3 species).Degradation level has no significant impact on species richness and Shannon-Wiener index of soil seed bank.In addition,sampling month and grassland degradation affected soil seed bank density,in which December>May>August,and ND>MD>HD,indicating that density of transient seed bank was greater than persistent seed bank.Soil seed bank density of surface layer(0–5 cm)accounting for 42%–72%of the total density,which was significantly higher than that of deep layer(5–10 cm).Similarity of species composition between vegetation and soil seed bank was low,and it increased with degradation level(ranged from 0.14 to 0.69).We concluded that grassland degradation affects soil seed bank density more than species diversity,and soil seed bank contributed slightly to vegetation regeneration of degraded alpine grassland.Therefore,it is unlikely that degraded alpine meadow can be restored solely through soil seed bank.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.U1733125)Natural Science Foundation of Tianjin(Grant No.17JCZDJC38700)
文摘The temperature field and flow field were analyzed to solve the problems of unstable penetration and poor forming quality,which always happen in asymmetric fillet welding. In order to explore the effect of the welding parameters on welding and improve the quality of forming,a three-dimensional mathematical model of asymmetric fillet welding was established by using the finite element software COMSOL and the coupling equation. The model was considered about the surface tension gradient,the electromagnetic force,gravity and the effect of temperature,radiation and convection heat on physical properties of the material. The flow field and the growth pattern of the weld pool were analyzed,and the weld pool geometry under different welding currents was compared. The results show that,the thin metal was preferentially penetrated,and with the welding process the weld width expanded until the weld beam was fullpenetration. The heat affected zone was got from weld experiments,its shape and size agreed well with the simulation results,which verifies the validity of the theoretical analysis.
文摘目的:探讨梧桐护理模式下父母陪伴麻醉诱导(parent presence at the induction of anesthesia,PPIA)对行肝穿刺活检术的肝移植状态患儿麻醉诱导期合作度及苏醒期谵妄(Emergence Delirium,ED)的影响。方法:采用随机数字表法,将2021年9月至2022年3月在全身麻醉下进行肝穿刺活检术的肝移植状态患儿124例分为对照组和观察组各62例。对照组给予常规护理模式下父母陪伴麻醉诱导,观察组行梧桐护理模式下父母陪伴麻醉诱导。比较两组患儿在麻醉诱导时、苏醒时、术后1 h的平均动脉压、心率变化。采用麻醉诱导期合作程度量表(Induction Checklist Compliance,ICC)比较两组患儿麻醉诱导时合作程度,采用苏醒期谵妄量表(Pediatric Anesthesia Emergence Delirium scale,PAED)比较两组患儿苏醒时、术后1 h、术后6 h、术后12 h谵妄评分及谵妄发生率。结果:两组患儿各时间点平均动脉压、心率组间比较差异无统计学意义(P>0.05);观察组患儿诱导时ICC评分低于对照组,苏醒时及术后1 h PAED评分均低于对照组,差异有统计学意义(P<0.05);两组患儿术后6 h、12 h PAED评分比较差异无统计学意义(P>0.05);观察组总体谵妄发生率低于对照组,差异有统计学意义(P<0.05)。结论:梧桐护理模式下父母陪伴麻醉诱导可提高肝移植后肝穿刺活检患儿麻醉诱导期合作程度,降低苏醒期谵妄发生率,对于加速患儿康复,提高患儿围手术期安全具有积极意义。
基金supported by the National Natural Science Foundation of China (31960279)the Science and Technology Program of Gansu Province, China (21JR11RA018)+1 种基金the Special Project for Central Universities to Build World-class Universities/Disciplines, and Characteristic Development GuidanceProgram for Changjiang Scholars and Innovative Research Team in University of Ministry of Education, China (IRT_17R88)
文摘Grassland degradation can alter the structure and function of ecosystem and soil seed bank.Therefore,estimating the role of soil seed bank in vegetation regeneration of degraded grasslands is crucial.We selected grasslands with three levels of degradation,namely non-degraded(ND),mildly degraded(MD),and heavily degraded(HD)to analyze the effect of grassland degradation on soil seed bank,as well as the role of soil seed bank on vegetation regeneration of the alpine grasslands,China.Soil samples from each level were collected in May,before seedling emergence,in August,after completion of transient seed bank germination,and in December,after seed dispersal,to determine the seed density and species composition through germination experiment.Result showed that a total of 35 plant species was identified,including 15 species observed in both soil seed bank and above-ground vegetation.A total of 19,15,and 14 species of soil seed bank were identified in December,May,and August,respectively.The most abundant species in soil seed bank were Compositae(5 species),followed by Poaceae(4 species),and Cyperaceae(3 species).Degradation level has no significant impact on species richness and Shannon-Wiener index of soil seed bank.In addition,sampling month and grassland degradation affected soil seed bank density,in which December>May>August,and ND>MD>HD,indicating that density of transient seed bank was greater than persistent seed bank.Soil seed bank density of surface layer(0–5 cm)accounting for 42%–72%of the total density,which was significantly higher than that of deep layer(5–10 cm).Similarity of species composition between vegetation and soil seed bank was low,and it increased with degradation level(ranged from 0.14 to 0.69).We concluded that grassland degradation affects soil seed bank density more than species diversity,and soil seed bank contributed slightly to vegetation regeneration of degraded alpine grassland.Therefore,it is unlikely that degraded alpine meadow can be restored solely through soil seed bank.
