Configuration errors are proved to be the main reasons for network interruption and anomalies.Many researchers have paid their attention to configuration analysis and provisioning,but few works focus on understanding ...Configuration errors are proved to be the main reasons for network interruption and anomalies.Many researchers have paid their attention to configuration analysis and provisioning,but few works focus on understanding the configuration evolution.In this paper,we uncover the configuration evolution of an operational IP backbone based on the weekly reports gathered from January 2006 to January 2013.We find that rate limiting and launching routes for new customers are configured most frequently.In addition,we conduct an analysis of network failures and find that link failures are the main causes for network failures.We suggest that we should configure redundant links for the links which are easy to break down.At last,according to the analysis results,we illustrate how to provide semi-automated configuration for rate limiting and adding customers.展开更多
Development of piezoelectric materials through chemical design meets the requirement of the nextgeneration electronic devices,yet the sensitive piezoelectricity to both chemical components and operational environment ...Development of piezoelectric materials through chemical design meets the requirement of the nextgeneration electronic devices,yet the sensitive piezoelectricity to both chemical components and operational environment call for the trial and error method during material preparation.In order to give an atomic-level understanding about functional unit and assist the chemical design,deep learning was applied to train a novelmodel based on themost popular BaTiO3 system,as a case study in this work.Through training the atomic force field of calcium and stannum doped solid-solution with Deep Potential method,3D structure of chemical distribution and corresponding polarization configuration can be constructed for different compositions under different temperatures,which exhibits a high degree of consistency with the local structure quantitatively analyzed from HAADF STEM and reverse Monte Carlo refinement of neutron total scattering data,especially for the critical composition with ultrahigh piezoelectricity of d33~860 pC/N.Systemic analysis reveals that variations in chemical bond length among various elements with oxygen elements are the primary factors influencing ferroelectric activity and leading to structural evolution.The results and methodology can facilitate the discovery of new ferroelectrics and the design of high-performance piezo/ferroelectrics with atomic-level insights.展开更多
This paper presents a five degree of freedom(5-DOF)redundantly actuated parallel mechanism(PM)for the parallel machining head of a machine tool.A 5-DOF single kinematic chain is evolved into a secondary kinematic chai...This paper presents a five degree of freedom(5-DOF)redundantly actuated parallel mechanism(PM)for the parallel machining head of a machine tool.A 5-DOF single kinematic chain is evolved into a secondary kinematic chain based on Lie group theory and a configuration evolution method.The evolutional chain and four 6-DOF kinematic chain SPS(S represents spherical joint and P represents prismatic joint)or UPS(U represents universal joint)can be combined into four classes of 5-DOF redundantly actuated parallel mechanisms.That SPS-(2UPR)R(R represents revolute joint)redundantly actuated parallel mechanism is selected and is applied to the parallel machining head of the machine tool.All formulas of the 4SPS-(2UPR)R mechanism are deduced.The dynamic model of the mechanism is shown to be correct by Matlab and automatic dynamic analysis of mechanical systems(ADAMS)under no-load conditions.The dynamic performance evaluation indexes including energy transmission efficiency and acceleration performance evaluation are analyzed.The results show that the 4SPS-(2UPR)R mechanism can be applied to a parallel machining head and have good dynamic performance.展开更多
基金supported by the National Natural Science Foundation of China under Grant Nos.61602105 and 61572123China Postdoctoral Science Foundation under Grant Nos.2016M601323+1 种基金the Fundamental Research Funds for the Central Universities Project under Grant No.N150403007CERNET Innovation Project under Grant No.NGII20160126
文摘Configuration errors are proved to be the main reasons for network interruption and anomalies.Many researchers have paid their attention to configuration analysis and provisioning,but few works focus on understanding the configuration evolution.In this paper,we uncover the configuration evolution of an operational IP backbone based on the weekly reports gathered from January 2006 to January 2013.We find that rate limiting and launching routes for new customers are configured most frequently.In addition,we conduct an analysis of network failures and find that link failures are the main causes for network failures.We suggest that we should configure redundant links for the links which are easy to break down.At last,according to the analysis results,we illustrate how to provide semi-automated configuration for rate limiting and adding customers.
基金supported by the National Key R&D Program of China(Grant No.2023YFB3508200)the Outstanding Young Scientist Program of Beijing Colleges and Universities(JWZQ20240101015)the National Natural Science Foundation of China(Grant Nos.92370104,22235002 and 52172181).We acknowledge the computational resource from Beijing PARATERA Tech Corp,LTD.
文摘Development of piezoelectric materials through chemical design meets the requirement of the nextgeneration electronic devices,yet the sensitive piezoelectricity to both chemical components and operational environment call for the trial and error method during material preparation.In order to give an atomic-level understanding about functional unit and assist the chemical design,deep learning was applied to train a novelmodel based on themost popular BaTiO3 system,as a case study in this work.Through training the atomic force field of calcium and stannum doped solid-solution with Deep Potential method,3D structure of chemical distribution and corresponding polarization configuration can be constructed for different compositions under different temperatures,which exhibits a high degree of consistency with the local structure quantitatively analyzed from HAADF STEM and reverse Monte Carlo refinement of neutron total scattering data,especially for the critical composition with ultrahigh piezoelectricity of d33~860 pC/N.Systemic analysis reveals that variations in chemical bond length among various elements with oxygen elements are the primary factors influencing ferroelectric activity and leading to structural evolution.The results and methodology can facilitate the discovery of new ferroelectrics and the design of high-performance piezo/ferroelectrics with atomic-level insights.
基金the Fundamental Research Funds for the Central Universities(No.2018 JBZ007).
文摘This paper presents a five degree of freedom(5-DOF)redundantly actuated parallel mechanism(PM)for the parallel machining head of a machine tool.A 5-DOF single kinematic chain is evolved into a secondary kinematic chain based on Lie group theory and a configuration evolution method.The evolutional chain and four 6-DOF kinematic chain SPS(S represents spherical joint and P represents prismatic joint)or UPS(U represents universal joint)can be combined into four classes of 5-DOF redundantly actuated parallel mechanisms.That SPS-(2UPR)R(R represents revolute joint)redundantly actuated parallel mechanism is selected and is applied to the parallel machining head of the machine tool.All formulas of the 4SPS-(2UPR)R mechanism are deduced.The dynamic model of the mechanism is shown to be correct by Matlab and automatic dynamic analysis of mechanical systems(ADAMS)under no-load conditions.The dynamic performance evaluation indexes including energy transmission efficiency and acceleration performance evaluation are analyzed.The results show that the 4SPS-(2UPR)R mechanism can be applied to a parallel machining head and have good dynamic performance.
