Fatigue failure continues to be a significant challenge in designing structural and mechanical components subjected to repeated and complex loading.While earlier studies mainly examined material properties and how str...Fatigue failure continues to be a significant challenge in designing structural and mechanical components subjected to repeated and complex loading.While earlier studies mainly examined material properties and how stress affects lifespan,this review offers the first comprehensive,multiscale comparison of strategies that optimize geometry to improve fatigue performance.This includes everything from microscopic features like the shape of graphite nodules to large-scale design elements such as fillets,notches,and overall structural layouts.We analyze and combine various methods,including topology and shape optimization,the ability of additive manufacturing to finetune internal geometries,and reliability-based design approaches.A key new contribution is our proposal of a standard way to evaluate geometry-focused fatigue design,allowing for consistent comparison and encouraging validation across different fields.Furthermore,we highlight important areas for future research,such as incorporating manufacturing flaws,using multiscale models,and integrating machine learning techniques.This work is the first to provide a broad geometric viewpoint in fatigue engineering,laying the groundwork for future design methods that are driven by data and centered on reliability.展开更多
The physicochemical properties of surfaces have a great effect on the micro-morphologies of the crystal structures which are in contact with them.Understanding the interaction mechanism between the internal driving fo...The physicochemical properties of surfaces have a great effect on the micro-morphologies of the crystal structures which are in contact with them.Understanding the interaction mechanism between the internal driving forces of the crystal and external inducing forces of the surfaces is the prerequisite of controlling and obtaining the desirable morphologies.In this work,the dynamic density functional theory was applied to construct the free energy functional expression of polyethylene(PE)lattice,and the micro-dynamic evolution processes of PE lattice morphology near the surfaces with different properties were observed to reveal the interaction mechanism at atomic scale.The results showed that the physical and chemical properties of the external surfaces synergistically affect the morphologies in both the defect shapes and the distribution of the defect regions.In the absence of the contact surfaces,driven by the oriented interactions among different CH2 groups,PE lattices gradually grow and form a defect-free structure.Conversely,the presence of contact surfaces leads to lattice defects in the interfacial regions,and PE lattice shows different self-healing abilities around different surfaces.展开更多
The selection and result of operative procedure for repairing atrioventricular septal defect (AVSD) are largely dependent on completeness and accuracy of preoperative morphological diagnosis. To evaluate the value of ...The selection and result of operative procedure for repairing atrioventricular septal defect (AVSD) are largely dependent on completeness and accuracy of preoperative morphological diagnosis. To evaluate the value of two dimensional echocardiographic (2DE) technique devised specifically for morpholagical diagnosis, the results of 2DE,angiocardiography and surgery were examined retrospectively in 87 children with AVSD.Age ranged from 3 months to 11 years old (mean 3.9 years). 46 had partial AVSD, 12 had transitional AVSD, 29 had complete AVSD (type A in 21, type B in 4, type C in 4).2DE diagnosis is concordant with surgical diagnosis in 36/37 (97%) patients with partial AVSD, in 25/31 (84%) patients with transitional or complete AVSD. Most discordant diagnosis between 2DE and surgery occurred in patients with transitional or type A AVSD.The 2DE technique for morphological diagnosis of A VSD is superior to angiocardiography.The results indicated that morphological manifestations of AVSD could be clearly demonstrated with the use of apical and subxiphoid 2D imaging planes, reliable morphological diagnosis could be obtained.展开更多
The replacement metal gate（RMG） defectivity performance control is very challenging in high-k metal gate（HKMG） chemical mechanical polishing（CMP）. In this study, three major defect types, including fall-on parti...The replacement metal gate（RMG） defectivity performance control is very challenging in high-k metal gate（HKMG） chemical mechanical polishing（CMP）. In this study, three major defect types, including fall-on particles, micro-scratch and corrosion have been investigated. The research studied the effects of polishing pad,pressure, rotating speed, flow rate and post-CMP cleaning on the three kinds of defect, which finally eliminated the defects and achieved good surface morphology. This study will provide an important reference value for the future research of aluminum metal gate CMP.展开更多
文摘Fatigue failure continues to be a significant challenge in designing structural and mechanical components subjected to repeated and complex loading.While earlier studies mainly examined material properties and how stress affects lifespan,this review offers the first comprehensive,multiscale comparison of strategies that optimize geometry to improve fatigue performance.This includes everything from microscopic features like the shape of graphite nodules to large-scale design elements such as fillets,notches,and overall structural layouts.We analyze and combine various methods,including topology and shape optimization,the ability of additive manufacturing to finetune internal geometries,and reliability-based design approaches.A key new contribution is our proposal of a standard way to evaluate geometry-focused fatigue design,allowing for consistent comparison and encouraging validation across different fields.Furthermore,we highlight important areas for future research,such as incorporating manufacturing flaws,using multiscale models,and integrating machine learning techniques.This work is the first to provide a broad geometric viewpoint in fatigue engineering,laying the groundwork for future design methods that are driven by data and centered on reliability.
基金supported by the National Natural Science Foundation of China(Nos.21476007,21673197,21621091)the National Key R&D Program of China(No.2018YFA0209500)+4 种基金the 111 Project(No.B16029)the Fundamental Research Funds for the Central Universities of China(No.20720190037)the Natural Science Foundation of Fujian Province of China(No.2018J06003)the Special Project of Strategic Emerging Industries from Fujian Development and Reform CommissionChemcloudcomputing of Beijing University of Chemical Technology。
文摘The physicochemical properties of surfaces have a great effect on the micro-morphologies of the crystal structures which are in contact with them.Understanding the interaction mechanism between the internal driving forces of the crystal and external inducing forces of the surfaces is the prerequisite of controlling and obtaining the desirable morphologies.In this work,the dynamic density functional theory was applied to construct the free energy functional expression of polyethylene(PE)lattice,and the micro-dynamic evolution processes of PE lattice morphology near the surfaces with different properties were observed to reveal the interaction mechanism at atomic scale.The results showed that the physical and chemical properties of the external surfaces synergistically affect the morphologies in both the defect shapes and the distribution of the defect regions.In the absence of the contact surfaces,driven by the oriented interactions among different CH2 groups,PE lattices gradually grow and form a defect-free structure.Conversely,the presence of contact surfaces leads to lattice defects in the interfacial regions,and PE lattice shows different self-healing abilities around different surfaces.
文摘The selection and result of operative procedure for repairing atrioventricular septal defect (AVSD) are largely dependent on completeness and accuracy of preoperative morphological diagnosis. To evaluate the value of two dimensional echocardiographic (2DE) technique devised specifically for morpholagical diagnosis, the results of 2DE,angiocardiography and surgery were examined retrospectively in 87 children with AVSD.Age ranged from 3 months to 11 years old (mean 3.9 years). 46 had partial AVSD, 12 had transitional AVSD, 29 had complete AVSD (type A in 21, type B in 4, type C in 4).2DE diagnosis is concordant with surgical diagnosis in 36/37 (97%) patients with partial AVSD, in 25/31 (84%) patients with transitional or complete AVSD. Most discordant diagnosis between 2DE and surgery occurred in patients with transitional or type A AVSD.The 2DE technique for morphological diagnosis of A VSD is superior to angiocardiography.The results indicated that morphological manifestations of AVSD could be clearly demonstrated with the use of apical and subxiphoid 2D imaging planes, reliable morphological diagnosis could be obtained.
基金Project supported by the Major National Science and Technology Special Projects(No.2009ZX02308)the Natural Science Foundation for the Youth of Hebei Province(Nos.F2012202094,F2015202267)the Outstanding Youth Science and Technology Innovation Fund of Hebei University of Technology(No.2013010)
文摘The replacement metal gate（RMG） defectivity performance control is very challenging in high-k metal gate（HKMG） chemical mechanical polishing（CMP）. In this study, three major defect types, including fall-on particles, micro-scratch and corrosion have been investigated. The research studied the effects of polishing pad,pressure, rotating speed, flow rate and post-CMP cleaning on the three kinds of defect, which finally eliminated the defects and achieved good surface morphology. This study will provide an important reference value for the future research of aluminum metal gate CMP.
