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Starved lubrication analysis of angular contact ball bearing based on a multi-degree-of-freedom tribo-dynamic model

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Friction 2023年第8期11卷 1395-1418页

作者： Chengwei WEN xianghui meng Jiaming GU Lin XIAO Shuang JIANG Hanbing BI State Key Laboratory of Mechanical System and Vibration Shanghai Jiaotong UniversityShanghai 200240China School of Mechanical Engineering Shanghai Jiaotong UniversityShanghai 200240China Bearing Technical Center Shanghai Prime Machinery Co.Ltd.Shanghai 201108China Shanghai Tian An Bearing Co. Ltd.Shanghai 201108China

When the oil supply is not adequate to maintain the ideal lubrication,angular contact ball bearing will enter into the starved lubrication regime resulting in the potential performance degradation and consequently the severe failures.To study the effects of starved lubrication on the performance of angular contact ball bearing,this paper first proposes a multi-degree-of-freedom(DOF)tribo-dynamic model by introducing five-DOF inner ring,six-DOF balls,and six-DOF cage.The model considers the starved lubrication in the ball-raceway contact and the full multi-body interactions between the bearing components.With different ball-raceway starvation degrees being analyzed,the effects of starved lubrication on the bearing tribo-dynamic performance are first revealed.By comparison,it is found that the oil film thickness,the skidding performance,and the traction forces in the ball-raceway contact are significantly influenced by the starvation degrees.It is also found that the starvation-induced change of the ball-pocket contact force is dramatical under combined loads,and the maximum contact force under this load condition increases with the increasing starvation degrees.

关键词： angular contact ball bearing starved lubrication tribo-dynamic performance multi-body interactions

Transient tribo-dynamic analysis of crosshead slipper in lowspeed marine diesel engines during engine startup

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Friction 2021年第6期9卷 1504-1527页

作者： Rui LI xianghui meng Jingjin DONG Wenda LI State Key Laboratory of Mechanical System and Vibration Shanghai Jiaotong UniversityShanghai 200240China School of Mechanical Engineering Shanghai Jiaotong UniversityShanghai 200240China China Shipbuilding Power Engineering Institute Company Limited Shanghai 201206China

A crosshead slipper-guide system,which bears a significant thrust force,is an essential friction pair in low-speed marine diesel engines.Owing to the low moving speed of the crosshead slipper during engine startup,it is difficult to form good hydrodynamic lubrication between the crosshead slipper and guide.Therefore,a detailed analysis of the crosshead slipper during engine startup is needed.In this study,a new transient tribo-dynamic model for a crosshead slipper during the engine startup process is presented.The model consists of a mixed lubrication model of the crosshead slipper-guide and dynamic models of the piston assembly,crosshead assembly,connecting rod,and crankshaft.The tribo-dynamic performances of the crosshead slipper during startup and under the rated conditions were simulated and compared.The results show that the tribo-dynamics of the crosshead slipper during the startup process are significantly different from those under the rated conditions.Some measures beneficial for the low friction of a crosshead slipper-guide under the rated conditions may significantly increase the friction loss of the crosshead slipper-guide system during the startup process.

关键词： low-speed marine diesel engine crosshead slipper engine start-up mixed lubrication friction loss tribo-dynamic model

Analysis of the coated and textured ring/liner conjunction based on a thermal mixed lubrication model

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Friction 2018年第4期6卷 420-431页

作者： Chunxing GU xianghui meng Di ZHANG State Key Laboratory of Mechanical System and Vibration Shanghai Jiaotong University School of Mechanical Engineering Shanghai Jiaotong University School of Mechanical Electronic Technology Shanghai Jianqiao University

For the ring/liner conjunction, well‐designed surface texturing has been regarded as a potential means to improve its tribological performance, as well as the application of coating. However, so far most researchers focused on the one of these aspects. In this study, the combined effect of coating and texturing on the performance of ring/liner conjunction is numerically investigated. A thermal mixed lubrication model is presented. The effects of the coating's thermal and mechanical properties on the tribological performance are studied under the cold and warm engine operating conditions. Along with the increasing coating thickness, the effects of the coating's thermal properties on friction loss are found to be significant, as well as the effects of the coating's mechanical properties. It is also found that a soft coating with a lower thermal inertia has a greater ability to reduce the friction loss of the textured conjunction.

关键词：表面纹理化摩擦学物理性能发展现状

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基于改进和声搜索的自适应DBSCAN算法

计算机工程与应用 2024年第6期60卷 147-154页

作者：孟祥辉魏照坤张笑菊韩志凤山东科技大学交通学院山东青岛266590 北京工商大学电商与物流学院北京100048

DBSCAN算法作为一种经典的聚类算法被广泛地应用于各领域,但由于其参数的自适应性较差,应用效果完全取决于参数的设置。基于此,提出了基于改进和声搜索的自适应DBSCAN算法,以提高DBSCAN算法的自适应性。算法采用K-平均最近邻算法优化初... 详细信息

DBSCAN算法作为一种经典的聚类算法被广泛地应用于各领域,但由于其参数的自适应性较差,应用效果完全取决于参数的设置。基于此,提出了基于改进和声搜索的自适应DBSCAN算法,以提高DBSCAN算法的自适应性。算法采用K-平均最近邻算法优化初始种群,从而改善初始种群质量,为后续的进化计算提供优质解;设计了基于双差分的更新算子,提升算法的搜索能力;采用两种更新策略结构避免算法过早收敛,提高和声搜索算法的寻优能力进而全面提升DBSCAN算法的自适应性。采用多种数据集并设计对比实验验证提出的算法。实验结果表明,提出的算法具有更佳的识别能力和自适应性。

关键词：自适应DBSCAN 和声搜索参数优化更新算子

院前静脉溶栓对STEMI患者微循环血流灌注及短期预后的疗效观察

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河北医药 2024年第13期46卷 1950-1954页

作者：安群英孟祥会潘吉亚孙国宁张敬河北省衡水市第六人民医院 053200

目的院前静脉溶栓对ST段抬高型心肌梗死(STEMI)患者经皮冠状动脉介入术(PCI)术中微循环血流灌注及短期预后的疗效。方法收集2022年6月至2023年6月收治的STEMI患者,根据再灌注策略,将患者分为院前静脉溶栓后PCI组(58例,A组)和急诊转运... 详细信息

目的院前静脉溶栓对ST段抬高型心肌梗死(STEMI)患者经皮冠状动脉介入术(PCI)术中微循环血流灌注及短期预后的疗效。方法收集2022年6月至2023年6月收治的STEMI患者,根据再灌注策略,将患者分为院前静脉溶栓后PCI组(58例,A组)和急诊转运PCI组(58例,B组)。比较2组介入术中情况、重要部位出血情况及主要不良心脑血管事件(MACCE)。结果 A组较B组再灌注时间明显缩短,术前TIMI血流分级≥2级比例增多,置入支架数量下降,术后无复流/慢血流发生率减少;术后7、30、90d复查心脏超声,A组左心室舒张末内径及WMSI下降,A组30、90 d LVEF升高(P0.05)。结论患者给予院前静脉溶栓能够缩短心肌缺血再灌注时间,减少术中微循环灌注障碍发生率,但主要出血事件和MACCE未增加。

关键词： ST段抬高型心肌梗死院前静脉溶栓经皮冠状动脉介入术无复流

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面向大型邮轮定制的模块化产品族设计方法研究

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船舶 2024年第1期35卷 41-49页

作者：程帅孟祥慧吕步高李瑞于学超上海交通大学机械与动力工程学院上海200240 上海外高桥造船有限公司上海200137

首艘国产邮轮已于2023年底交付,预计邮轮产业将在未来为中国经济作出重要贡献。然而,中国企业在邮轮自主设计方面还有很长的路要走,需要考虑未来的发展趋势并提前进行设计和布局。作为娱乐载具,邮轮要满足不同区域和文化下的定制需求;同... 详细信息

首艘国产邮轮已于2023年底交付,预计邮轮产业将在未来为中国经济作出重要贡献。然而,中国企业在邮轮自主设计方面还有很长的路要走,需要考虑未来的发展趋势并提前进行设计和布局。作为娱乐载具,邮轮要满足不同区域和文化下的定制需求;同时,由于系统的复杂性,任何更改都会给邮轮设计带来巨大的成本。该文针对此问题,分析了大型邮轮功能模块的构成以及定制化设计的可行性,提出了大型邮轮模块化产品族设计方法以及基于产品族的大型邮轮定制化设计流程。面向大型邮轮定制的模块化产品族理念与设计方法,有利于邮轮功能设计的完备性和邮轮定制的高效性,可为未来国产大型邮轮的自主设计提供支持。

关键词：大型邮轮产品族功能设计模块化定制

A deterministic FE contact analysis of 3D rough surfaces with textures and comparison with classic statistical contact models

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Science China(Technological Sciences) 2021年第2期64卷 297-316页

作者： ZHANG Rui meng xianghui LYU BuGao SUN Kai School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China AECC Commercial Aircraft Engine Company Limited Shanghai 200241China

Accurate contact calculations of real rough surfaces are fundamental but complicated. The model-based methods are convenient and straightforward. But these methods ignore some factors and may lead to less accurate results. This is especially true when considering multi-scale topographic features of engineering rough surfaces. Based on artificially generated rough surfaces, the deterministic contact analysis of two 3D rough surfaces is conducted by the finite element method(FEM). The calculations show that when the separation between surfaces reduces, results of classic model-based methods are quite different from those of this study, especially when the roughness distribution and textures are considered. As friction pairs are working under increasing harsh conditions, the accurate contact calculation in this paper will be of great significance.

关键词： deterministic contact analysis multi-scale topography finite element method(FEM) engineering rough surfaces

Blow-by and tribological performance of piston ring pack during cold start and warm idle operations

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Science China(Technological Sciences) 2016年第7期59卷 1085-1099页

作者： CHENG Jun meng xianghui XIE YouBai KONG XiaoLi School of Mechanical Engineering Shanghai Jiaotong University Shanghai 200240 China Research and Development Center of China's First Automotive Works (FAW) Group Changchun 130011 China

To reduce the fuel consumption of internal combustion engines, more attention has been paid to the tribological performance of the piston ring pack during the cold start and idle operations. In this research, a numerical model considering the cylinder liner deformation and the piston ring conformability is developed to predict the blow-by, lubrication, friction and wear of the piston ring pack under different operating conditions. The gas flow rate, inter-ring gas pressures, minimum oil film thickness, frictional force and wear load during cold start are calculated and compared with those during warm idle operating conditions. The results show that cylinder liner deformation and piston ring conformability together obviously affect blow-by and other tribological performance. Meanwhile, it is found that friction loss is larger during cold start than during warm idle operating conditions. However, the wear process is more severe during warm idle operation than during cold start. From this research, the blow-by and tribological performance of the piston ring pack during cold start and warm idle operations are understood more deeply.

关键词：摩擦磨损性能活塞环组怠速工况操作过程冷启动最小油膜厚度气体流量启动过程

Advances in the molecular genetics of parathyroid tumors

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Chinese Medical Journal 2024年第3期137卷 376-378页

作者： Liwei Zhao xianghui He Department of General Surgery Tianjin Medical University General HospitalTianjin 300052China

To the Editor:Parathyroid tumors are endocrine tumors that can lead to disorders of calcium and phosphorus metabolism and involve multiple organ systems.In the past,the genetics of parathyroid tumors have been well established,and the significant roles of genes such as MEN1,CDC73,and CCND1 in the process of parathyroid tumorigenesis have been identified and confirmed[Table 1].However,with further research and the widespread use of sequencing technology,“new”roles for“old”genes and new pathogenic mechanisms have been discovered.

关键词： metabolism tumors parathyroid