针对某航天电子管壳焊接组件冷却过程中的热力耦合影响问题,建立了焊接组件的有限元热分析模型,研究了在快速冷却过程中梯度材料分布对低温共烧陶瓷(low temperature co-fired ceramic,LTCC)基板、梯度管壳的残余应力和变形的影响。以...针对某航天电子管壳焊接组件冷却过程中的热力耦合影响问题,建立了焊接组件的有限元热分析模型,研究了在快速冷却过程中梯度材料分布对低温共烧陶瓷(low temperature co-fired ceramic,LTCC)基板、梯度管壳的残余应力和变形的影响。以不超过基板断裂强度为前提条件,以降低管壳整体的残余应力与变形为优化目标,采用了多因素变换优选法,确定了管壳材料的最优梯度分布方案,即合金管壳自上而下的梯度分布为Al-35Si、Al-42Si、Al-50Si、Al-60Si、Al-70Si。其中,Al-35Si厚度为2.5mm,Al-42Si与Al-60Si的厚度均为1.6mm,Al-50Si厚度为0.8mm,Al-70Si厚度为2mm。在该方案下,LTCC基板冷却至室温时的最大变形量为4.86μm,最大第一主应力为6761MPa,远小于LTCC材料的断裂强度320MPa;管壳冷却至室温时的最大变形量为18.291μm,最大残余应力值为20.46MPa,远小于管壳材料的屈服强度100MPa。管壳各层之间的应力集中现象不明显,管壳的整体焊接质量得到提升。展开更多
Artificial vegetation restoration is the main measure for vegetation restoration and soil and water conservation in alpine mine dumps on the Qinghai-Tibet Plateau,China.However,there are few reports on the dynamic cha...Artificial vegetation restoration is the main measure for vegetation restoration and soil and water conservation in alpine mine dumps on the Qinghai-Tibet Plateau,China.However,there are few reports on the dynamic changes and the influencing factors of the soil reinforcement effect of plant species after artificial vegetation restoration under different recovery periods.We selected dump areas of the Delni Copper Mine in Qinghai Province,China to study the relationship between the shear strength and the peak displacement of the root-soil composite on the slope during the recovery period,and the influence of the root traits and soil physical properties on the shear resistance characteristics of the root-soil composite via in situ direct shear tests.The results indicate that the shear strength and peak displacement of the rooted soil initially decreased and then increased with the increase of the recovery period.The shear strength of the rooted soil and the recovery period exhibited a quadratic function relationship.There is no significant function relationship between the peak displacement and the recovery period.Significant positive correlations(P<0.05)exists between the shear strength of the root-soil composite and the root biomass density,root volume density,and root area ratio,and they show significant linear correlations(P<0.05).There are no significant correlations(P>0.05)between the shear strength of the root-soil composite and the root length density,and the root volume ratio of the coarse roots to the fine roots.A significant negative linear correlation(P<0.05)exists between the peak displacement of the rooted soil and the coarse-grain content,but no significant correlations(P>0.05)with the root traits,other soil physical property indices(the moisture content and dry density of the soil),and slope gradient.The coarse-grain content is the main factor controlling the peak displacement of the rooted soil.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
在车辆起步过程中,发动机输出转矩波动会导致离合器接合不稳定,从而影响整车动力传动系统的平顺性。双质量飞轮(dual mass flywheel,DMF)可减小发动机转矩波动对离合器及整车动力传动系统的影响。针对起步过程离合器接合不稳定影响整车...在车辆起步过程中,发动机输出转矩波动会导致离合器接合不稳定,从而影响整车动力传动系统的平顺性。双质量飞轮(dual mass flywheel,DMF)可减小发动机转矩波动对离合器及整车动力传动系统的影响。针对起步过程离合器接合不稳定影响整车平顺性的问题,以双离合器自动变速器(dual clutch automatic transmission,DCT)车辆为研究对象,研究了DMF的刚度、阻尼和初级与次级飞轮惯量比对DCT车辆起步过程离合器接合稳定性的影响,并建立了以离合器黏滑比和整车冲击度为目标函数的多目标优化模型,利用遗传算法对模型进行优化,得到了使离合器接合稳定性提高且整车冲击度明显降低的DMF最优参数组合。展开更多
文摘针对某航天电子管壳焊接组件冷却过程中的热力耦合影响问题,建立了焊接组件的有限元热分析模型,研究了在快速冷却过程中梯度材料分布对低温共烧陶瓷(low temperature co-fired ceramic,LTCC)基板、梯度管壳的残余应力和变形的影响。以不超过基板断裂强度为前提条件,以降低管壳整体的残余应力与变形为优化目标,采用了多因素变换优选法,确定了管壳材料的最优梯度分布方案,即合金管壳自上而下的梯度分布为Al-35Si、Al-42Si、Al-50Si、Al-60Si、Al-70Si。其中,Al-35Si厚度为2.5mm,Al-42Si与Al-60Si的厚度均为1.6mm,Al-50Si厚度为0.8mm,Al-70Si厚度为2mm。在该方案下,LTCC基板冷却至室温时的最大变形量为4.86μm,最大第一主应力为6761MPa,远小于LTCC材料的断裂强度320MPa;管壳冷却至室温时的最大变形量为18.291μm,最大残余应力值为20.46MPa,远小于管壳材料的屈服强度100MPa。管壳各层之间的应力集中现象不明显,管壳的整体焊接质量得到提升。
基金supported by the Project of Qinghai Science&Technology Department(Grant No.2021-ZJ-956Q).
文摘Artificial vegetation restoration is the main measure for vegetation restoration and soil and water conservation in alpine mine dumps on the Qinghai-Tibet Plateau,China.However,there are few reports on the dynamic changes and the influencing factors of the soil reinforcement effect of plant species after artificial vegetation restoration under different recovery periods.We selected dump areas of the Delni Copper Mine in Qinghai Province,China to study the relationship between the shear strength and the peak displacement of the root-soil composite on the slope during the recovery period,and the influence of the root traits and soil physical properties on the shear resistance characteristics of the root-soil composite via in situ direct shear tests.The results indicate that the shear strength and peak displacement of the rooted soil initially decreased and then increased with the increase of the recovery period.The shear strength of the rooted soil and the recovery period exhibited a quadratic function relationship.There is no significant function relationship between the peak displacement and the recovery period.Significant positive correlations(P<0.05)exists between the shear strength of the root-soil composite and the root biomass density,root volume density,and root area ratio,and they show significant linear correlations(P<0.05).There are no significant correlations(P>0.05)between the shear strength of the root-soil composite and the root length density,and the root volume ratio of the coarse roots to the fine roots.A significant negative linear correlation(P<0.05)exists between the peak displacement of the rooted soil and the coarse-grain content,but no significant correlations(P>0.05)with the root traits,other soil physical property indices(the moisture content and dry density of the soil),and slope gradient.The coarse-grain content is the main factor controlling the peak displacement of the rooted soil.
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。
