Surface texturing has been applied to improving the tribological performance of mechanical components for many years. Currently, the researches simulate the film pressure distribution of textured rough surfaces on the...Surface texturing has been applied to improving the tribological performance of mechanical components for many years. Currently, the researches simulate the film pressure distribution of textured rough surfaces on the basis of the average flow model, and however the influence of roughness on the film pressure distribution could not be precisely expressed. Therefore, in order to study the hydrodynamic lubrication of the rough textured surfaces, sinusoidal waves are employed to characterize untextured surfaces. A deterministic model for hydrodynamic lubrication of microdimple textured rough surfaces is developed to predict the distribution of hydrodynamic pressure. By supplementing with the JFO cavitation boundary, the load carrying capacity of the film produced by micro-dimples and roughness is obtained. And the geometric parameters of textured rough surface are optimized to obtain the maximum hydrodynamic lubrication by specifying an optimization goal of the load carrying capacity. The effect of roughness on the hydrodynamic pressure of surface texture is significant and the load carrying capacity decreases with the increase of the roughness ratio because the roughness greatly suppresses the hydrodynamic effect of dimples. It shows that the roughness ratio of surface may be as small as possible to suppress the effect of hydrodynamic lubrication. Additionally,there are the optimum values of the micro-dimple depth and area density to maximize the load carrying capacity for any given value of the roughness ratio. The proposed approach is capable of accurately reflects the influence of roughness on the hydrodynamic pressure, and developed a deterministic model to investigate the hydrodynamic lubrication of textured surfaces.展开更多
多年来,全球肠外肠内营养学界同道们都在寻求营养不良诊断标准的统一,既需要确定营养不良诊断标准,也需要考虑营养不良指标在不同国家、不同种族的正常值和按临床研究得到的切割点(cut-off point)。全球(营养)领导层倡议营养不良(Global...多年来,全球肠外肠内营养学界同道们都在寻求营养不良诊断标准的统一,既需要确定营养不良诊断标准,也需要考虑营养不良指标在不同国家、不同种族的正常值和按临床研究得到的切割点(cut-off point)。全球(营养)领导层倡议营养不良(Global Leadership Initiative on Malnutrition,GLIM)诊断标准于2018年9月在美国肠外肠内营养学会(American Society for Parenteral and Enteral Nutrition,ASPEN)和欧洲临床营养和代谢学会(European Society for Clinical Nutrition and Metabolism,ESPEN)网站发表。2019年初在纸质版杂志《JPEN》及《Clinical Nutrition》发表。GLIM在《全国科学技术名词审定委员会-肠外肠内营养学分名词-2019》有记载。GLIM中的某些阈值可能会随着时间的推移而有演变,但是从主观评定营养不良(如SGA、PG-SGA),发展到用表现型指标、病因型指标诊断营养不良的方向是正确的。高质量的前瞻性临床有效性验证报告和前瞻性多中心临床应用数据分析,将是GLIM改进的基础。2016年《疾病分类与代码》GB/T(中国ICD-10扩充版)及2019年《关于全国三级公立医院绩效考核通知〔2019〕》以及国家医保局信息业务数据库等三个方面文件均收录了营养风险、营养不良、重度(严重)营养不良作为疾病名称。目前临床各学科都在推行个体化医疗,但是临床各科室的实际情况不同。对肠外肠内营养支持疗法的临床应用来说,与对癌症患者的精准医疗、靶向治疗是有很大的距离。2004年12月,中华医学会肠外肠内营养学分会(Chinese Society for Parenteral and Enteral Nutritional,CSPEN)常委会组建营养风险-不足-营养支持-结局-成本效果比(Nutritional risk-undernutrition-support-outcome-cost effectiveness ratio,NUSOC)多中心分享数据库协作组,该协作组的目标是分出哪些患者需要肠外肠内营养支持疗法,合理应用前提下让患者受益。中国的疾病诊断相关分组展开更多
基金Supported by National Natural Science Foundation of China(Grant Nos.51305168,51375211,51375213)Jiangsu Provincial Natural Science Foundation of China(Grant No.BK20130524)Research Foundation for Advanced Talents of Jiangsu University,China(Grant No.13JDG090)
文摘Surface texturing has been applied to improving the tribological performance of mechanical components for many years. Currently, the researches simulate the film pressure distribution of textured rough surfaces on the basis of the average flow model, and however the influence of roughness on the film pressure distribution could not be precisely expressed. Therefore, in order to study the hydrodynamic lubrication of the rough textured surfaces, sinusoidal waves are employed to characterize untextured surfaces. A deterministic model for hydrodynamic lubrication of microdimple textured rough surfaces is developed to predict the distribution of hydrodynamic pressure. By supplementing with the JFO cavitation boundary, the load carrying capacity of the film produced by micro-dimples and roughness is obtained. And the geometric parameters of textured rough surface are optimized to obtain the maximum hydrodynamic lubrication by specifying an optimization goal of the load carrying capacity. The effect of roughness on the hydrodynamic pressure of surface texture is significant and the load carrying capacity decreases with the increase of the roughness ratio because the roughness greatly suppresses the hydrodynamic effect of dimples. It shows that the roughness ratio of surface may be as small as possible to suppress the effect of hydrodynamic lubrication. Additionally,there are the optimum values of the micro-dimple depth and area density to maximize the load carrying capacity for any given value of the roughness ratio. The proposed approach is capable of accurately reflects the influence of roughness on the hydrodynamic pressure, and developed a deterministic model to investigate the hydrodynamic lubrication of textured surfaces.
文摘多年来,全球肠外肠内营养学界同道们都在寻求营养不良诊断标准的统一,既需要确定营养不良诊断标准,也需要考虑营养不良指标在不同国家、不同种族的正常值和按临床研究得到的切割点(cut-off point)。全球(营养)领导层倡议营养不良(Global Leadership Initiative on Malnutrition,GLIM)诊断标准于2018年9月在美国肠外肠内营养学会(American Society for Parenteral and Enteral Nutrition,ASPEN)和欧洲临床营养和代谢学会(European Society for Clinical Nutrition and Metabolism,ESPEN)网站发表。2019年初在纸质版杂志《JPEN》及《Clinical Nutrition》发表。GLIM在《全国科学技术名词审定委员会-肠外肠内营养学分名词-2019》有记载。GLIM中的某些阈值可能会随着时间的推移而有演变,但是从主观评定营养不良(如SGA、PG-SGA),发展到用表现型指标、病因型指标诊断营养不良的方向是正确的。高质量的前瞻性临床有效性验证报告和前瞻性多中心临床应用数据分析,将是GLIM改进的基础。2016年《疾病分类与代码》GB/T(中国ICD-10扩充版)及2019年《关于全国三级公立医院绩效考核通知〔2019〕》以及国家医保局信息业务数据库等三个方面文件均收录了营养风险、营养不良、重度(严重)营养不良作为疾病名称。目前临床各学科都在推行个体化医疗,但是临床各科室的实际情况不同。对肠外肠内营养支持疗法的临床应用来说,与对癌症患者的精准医疗、靶向治疗是有很大的距离。2004年12月,中华医学会肠外肠内营养学分会(Chinese Society for Parenteral and Enteral Nutritional,CSPEN)常委会组建营养风险-不足-营养支持-结局-成本效果比(Nutritional risk-undernutrition-support-outcome-cost effectiveness ratio,NUSOC)多中心分享数据库协作组,该协作组的目标是分出哪些患者需要肠外肠内营养支持疗法,合理应用前提下让患者受益。中国的疾病诊断相关分组
