A marine riser,one of the most important components of offshore oil/gas transportation,needs to be designed to eliminate the risks caused by complex ocean environments,platform displacement and internal corrosion,etc....A marine riser,one of the most important components of offshore oil/gas transportation,needs to be designed to eliminate the risks caused by complex ocean environments,platform displacement and internal corrosion,etc.In this study,a new analytical-numerical assessment approach is proposed in order to quantitatively investigate the reliability of internally corroded risers under combined loads including axial tension and internal pressure.First,an analytical solution of the limit state function of intact risers under combined loads is obtained,which is further modified by the non-dimensional corrosion depth （d/ t） for the risers with a narrow and long corrosion defect.The relationship between d/t and limited internal pressure is obtained by finite element analysis and nonlinear regression.Through an advanced first-order reliability method （HL-RF） algorithm,reliability analysis is performed to obtain the failure probability,the reliability index and the sensitivity.These results are further verified by Monte-Carlo importance sampling.The proposed approach of reliability analysis provides an accurate and effective way to estimate the reliability of marine risers with narrow and long corrosion defects under combined loads.展开更多
Chip designers employ computer-aided design,circuit simulation,and design rule check systems.Lithography engineers employ model-based OPC(Optical Proximity Correction)and model-based print-simulation systems.Reticle i...Chip designers employ computer-aided design,circuit simulation,and design rule check systems.Lithography engineers employ model-based OPC(Optical Proximity Correction)and model-based print-simulation systems.Reticle inspection teams employ Aerial Image Measurement Systems®and Virtual Stepper®Systems.These teams are accustomed to evaluating and deploying state-of-the-art computational systems.When real-silicon fabrication begins,however,the teams responsible for line monitoring,wafer inspection,and yield attainment operate without the benefit of similarly advanced computational systems.In this paper we describe such a system and explore its applications and benefits.The system has received three U.S.patents[1-3]and brings together the significant potential of CAD(Computer Aided Design)layout(GDS,OASIS),Die-to-Database,and Machine Learning to build a dynamic,self-improving computational system.Featuring care area generation,advanced machine learning-based SEM(Scanning Electron Microscope)sampling that optimizes both DOI(Defect of Interest)capture rate and discovery of new defect types,comprehensive extraction of all Information of Interest(IOI)from all SEM images,detection of defect types not possible before,massive pattern fidelity analysis,full chip pattern decomposition and risk scoring via machine learning,innovative PWQ(Process Window Qualification)analysis and process window determination,risk assessment of new tape-outs,large scale in-wafer OPC verification and more,the system delivers a comprehensive pattern centric platform for process technology development and manufacturing.展开更多
基金the National Basic Research Program of China(973 Program,Grant No.2011CB013702)the Beijing Natural Science Foundation(Grant No.KZ201210017017)
文摘A marine riser,one of the most important components of offshore oil/gas transportation,needs to be designed to eliminate the risks caused by complex ocean environments,platform displacement and internal corrosion,etc.In this study,a new analytical-numerical assessment approach is proposed in order to quantitatively investigate the reliability of internally corroded risers under combined loads including axial tension and internal pressure.First,an analytical solution of the limit state function of intact risers under combined loads is obtained,which is further modified by the non-dimensional corrosion depth （d/ t） for the risers with a narrow and long corrosion defect.The relationship between d/t and limited internal pressure is obtained by finite element analysis and nonlinear regression.Through an advanced first-order reliability method （HL-RF） algorithm,reliability analysis is performed to obtain the failure probability,the reliability index and the sensitivity.These results are further verified by Monte-Carlo importance sampling.The proposed approach of reliability analysis provides an accurate and effective way to estimate the reliability of marine risers with narrow and long corrosion defects under combined loads.
文摘Chip designers employ computer-aided design,circuit simulation,and design rule check systems.Lithography engineers employ model-based OPC(Optical Proximity Correction)and model-based print-simulation systems.Reticle inspection teams employ Aerial Image Measurement Systems®and Virtual Stepper®Systems.These teams are accustomed to evaluating and deploying state-of-the-art computational systems.When real-silicon fabrication begins,however,the teams responsible for line monitoring,wafer inspection,and yield attainment operate without the benefit of similarly advanced computational systems.In this paper we describe such a system and explore its applications and benefits.The system has received three U.S.patents[1-3]and brings together the significant potential of CAD(Computer Aided Design)layout(GDS,OASIS),Die-to-Database,and Machine Learning to build a dynamic,self-improving computational system.Featuring care area generation,advanced machine learning-based SEM(Scanning Electron Microscope)sampling that optimizes both DOI(Defect of Interest)capture rate and discovery of new defect types,comprehensive extraction of all Information of Interest(IOI)from all SEM images,detection of defect types not possible before,massive pattern fidelity analysis,full chip pattern decomposition and risk scoring via machine learning,innovative PWQ(Process Window Qualification)analysis and process window determination,risk assessment of new tape-outs,large scale in-wafer OPC verification and more,the system delivers a comprehensive pattern centric platform for process technology development and manufacturing.
