Better understanding of alveolar mechanics is very important in order to avoid lung injuries for patients undergoing mechanical ventilation for treatment of respiratory problems. The objective of this study was to inv...Better understanding of alveolar mechanics is very important in order to avoid lung injuries for patients undergoing mechanical ventilation for treatment of respiratory problems. The objective of this study was to investigate the alveolar mechanics for two different alveolar sac models, one based on actual geometry and the other an idealized spherical geometry using coupled fluid-solid computational analysis. Both the models were analyzed through coupled fluid-solid analysis to estimate the parameters such as pressures/ velocities and displacements/stresses under mechanical ventilation conditions. The results obtained from the fluid analysis indicate that both the alveolar geometries give similar results for pressures and velocities. However, the results obtained from coupled fluid-solid analysis indicate that the actual alveolar geometry results in smaller displacements in comparison to a spherical alveolar model. This trend is also true for stress/strain between the two models. The results presented indicate that alveolar geometry greatly affects the pressure/velocities as well as displacements and stresses/strains.展开更多
针对工业装配任务,尤其是不规则轴孔工件装配中,基于学习的前期样本质量低、训练过程不稳定等问题,提出一种融合引斥力模型(Attraction-Repulsion Model,ARM)引导机制和长短期记忆网络(Long Short Term Memory,LSTM)的柔性演员-评论家(S...针对工业装配任务,尤其是不规则轴孔工件装配中,基于学习的前期样本质量低、训练过程不稳定等问题,提出一种融合引斥力模型(Attraction-Repulsion Model,ARM)引导机制和长短期记忆网络(Long Short Term Memory,LSTM)的柔性演员-评论家(Soft Actor-Critic,SAC)算法。首先,为解决训练初期探索效率低的问题,提出一种基于引斥力模型的策略引导机制,通过目标位置信息引导机械臂运动,加速收敛过程;其次,基于长短期记忆网络对算法的策略网络和价值网络进行改进,有效利用历史信息,增强策略学习能力,提高算法的收敛速度和稳定性。仿真结果表明,所提出的算法在行星减速器中心轴装配任务中取得显著的效果,装配成功率高达99.4%,与普通SAC算法相比,平均最大接触力和力矩分别降低了68.8%和79.2%。在物理环境中装配成功率达95%以上,最大接触力和力矩分别小于10 N和1.5 N·m,验证了算法的有效性。展开更多
水飞蓟素是水飞蓟种子提取出的黄酮类生物活性成分,具有保肝利胆等多种药理功能,其中水飞蓟宾活性及含量最高,本研究利用天然低共熔溶剂(Natural Deep Eutectic Solvent,NADES),对水飞蓟宾的高效提取工艺与机理进行研究。以粉碎脱脂后...水飞蓟素是水飞蓟种子提取出的黄酮类生物活性成分,具有保肝利胆等多种药理功能,其中水飞蓟宾活性及含量最高,本研究利用天然低共熔溶剂(Natural Deep Eutectic Solvent,NADES),对水飞蓟宾的高效提取工艺与机理进行研究。以粉碎脱脂后的水飞蓟种壳粉为原料,用初步筛选所得较优NADES,即:氯化胆碱+1,4-丁二醇进行提取,HPLC法测定水飞蓟宾含量,在单因素实验基础上,采用响应面法对该NADES提取水飞蓟宾工艺进行优化。结果表明:料液比1:20 g/mL,提取温度77.0℃、时间5.6 h,模型预测水飞蓟宾得率可达4.29%,与实验值4.30%基本一致。基于片段活度系数类导体屏蔽模型(Conductor-like Screening Model for Segment Activity Coefficient,COSMO-SAC),分别对水飞蓟宾和溶剂分子(NADES与传统溶剂乙醇)进行结构与能量优化,通过量子化学计算,得到水飞蓟宾在两种溶剂中的无限稀释活度系数的对数分别为-6.922和-6.043,分子间相互作用能分别为-51.62和-25.47 kJ/mol,以探讨不同溶剂提取水飞蓟宾效果差异机理。展开更多
文摘Better understanding of alveolar mechanics is very important in order to avoid lung injuries for patients undergoing mechanical ventilation for treatment of respiratory problems. The objective of this study was to investigate the alveolar mechanics for two different alveolar sac models, one based on actual geometry and the other an idealized spherical geometry using coupled fluid-solid computational analysis. Both the models were analyzed through coupled fluid-solid analysis to estimate the parameters such as pressures/ velocities and displacements/stresses under mechanical ventilation conditions. The results obtained from the fluid analysis indicate that both the alveolar geometries give similar results for pressures and velocities. However, the results obtained from coupled fluid-solid analysis indicate that the actual alveolar geometry results in smaller displacements in comparison to a spherical alveolar model. This trend is also true for stress/strain between the two models. The results presented indicate that alveolar geometry greatly affects the pressure/velocities as well as displacements and stresses/strains.
文摘针对工业装配任务,尤其是不规则轴孔工件装配中,基于学习的前期样本质量低、训练过程不稳定等问题,提出一种融合引斥力模型(Attraction-Repulsion Model,ARM)引导机制和长短期记忆网络(Long Short Term Memory,LSTM)的柔性演员-评论家(Soft Actor-Critic,SAC)算法。首先,为解决训练初期探索效率低的问题,提出一种基于引斥力模型的策略引导机制,通过目标位置信息引导机械臂运动,加速收敛过程;其次,基于长短期记忆网络对算法的策略网络和价值网络进行改进,有效利用历史信息,增强策略学习能力,提高算法的收敛速度和稳定性。仿真结果表明,所提出的算法在行星减速器中心轴装配任务中取得显著的效果,装配成功率高达99.4%,与普通SAC算法相比,平均最大接触力和力矩分别降低了68.8%和79.2%。在物理环境中装配成功率达95%以上,最大接触力和力矩分别小于10 N和1.5 N·m,验证了算法的有效性。
文摘水飞蓟素是水飞蓟种子提取出的黄酮类生物活性成分,具有保肝利胆等多种药理功能,其中水飞蓟宾活性及含量最高,本研究利用天然低共熔溶剂(Natural Deep Eutectic Solvent,NADES),对水飞蓟宾的高效提取工艺与机理进行研究。以粉碎脱脂后的水飞蓟种壳粉为原料,用初步筛选所得较优NADES,即:氯化胆碱+1,4-丁二醇进行提取,HPLC法测定水飞蓟宾含量,在单因素实验基础上,采用响应面法对该NADES提取水飞蓟宾工艺进行优化。结果表明:料液比1:20 g/mL,提取温度77.0℃、时间5.6 h,模型预测水飞蓟宾得率可达4.29%,与实验值4.30%基本一致。基于片段活度系数类导体屏蔽模型(Conductor-like Screening Model for Segment Activity Coefficient,COSMO-SAC),分别对水飞蓟宾和溶剂分子(NADES与传统溶剂乙醇)进行结构与能量优化,通过量子化学计算,得到水飞蓟宾在两种溶剂中的无限稀释活度系数的对数分别为-6.922和-6.043,分子间相互作用能分别为-51.62和-25.47 kJ/mol,以探讨不同溶剂提取水飞蓟宾效果差异机理。
