Nuclear industries have faced the unfavorable circumstance such as components obsolescence and aging of instrumentation and control system, therefore, nuclear society is striving to resolve this issue fundamentally. V...Nuclear industries have faced the unfavorable circumstance such as components obsolescence and aging of instrumentation and control system, therefore, nuclear society is striving to resolve this issue fundamentally. Various studies have been conducted to address components obsolescence of instrumentation and control system. Intuitively FPGA （field programmable gate arrays） technology is replacing the high level of micro-processor type equipped with various software and hardware which causes acceleration of the aging and obsolescence in I ＆ C （instrumentation and control） system in nuclear power plants. FPGAs are highlighted as an alternative means for obsolete control systems. When engineers design the control system of NPPs （nuclear power plants） with FPGAs, it is important to meet the system development life cycles and conduct the verification and validation activities regarding to FPGA-based applications for use in NPPs. Because the verification and validation process is more important than the design process, engineer should consider the characteristics of FPGA, HDL （hardware description language） programming, faults mode, and optimization technique. And also these characteristics should be reflected in verification and validation activities. As a minimum requirement, system designers require that HDL-programmed applications should be developed in accordance with system development life cycle and HPD design process. In the verification and validation processes, a review, test, and analysis activities should be properly conducted.展开更多
In this paper,we analyze the stress and electric field intensity factors affected by residual surface stress for conducting cracks in piezoelectric nanomaterials.The problem is reduced to a system of non-linear singul...In this paper,we analyze the stress and electric field intensity factors affected by residual surface stress for conducting cracks in piezoelectric nanomaterials.The problem is reduced to a system of non-linear singular integral equations,whose solution is determined by iteration technique.Numerical results indicate that the residual surface stress can significantly alter the crack tip fields at nanometer length scales.Due to the residual surface stress,281he electric field can produce stress around crack tip.This suggests a strong electromechanical coupling crack tip field for nanoscale piezoelectric materials.Such a finding is considerably different from the classical fracture mechanics results.A transit electric field to stress load ratio is identified,for which influences of residual surface stresses vanish.The research is useful for the applications of nanoscale piezoelectric devices.展开更多
文摘Nuclear industries have faced the unfavorable circumstance such as components obsolescence and aging of instrumentation and control system, therefore, nuclear society is striving to resolve this issue fundamentally. Various studies have been conducted to address components obsolescence of instrumentation and control system. Intuitively FPGA （field programmable gate arrays） technology is replacing the high level of micro-processor type equipped with various software and hardware which causes acceleration of the aging and obsolescence in I ＆ C （instrumentation and control） system in nuclear power plants. FPGAs are highlighted as an alternative means for obsolete control systems. When engineers design the control system of NPPs （nuclear power plants） with FPGAs, it is important to meet the system development life cycles and conduct the verification and validation activities regarding to FPGA-based applications for use in NPPs. Because the verification and validation process is more important than the design process, engineer should consider the characteristics of FPGA, HDL （hardware description language） programming, faults mode, and optimization technique. And also these characteristics should be reflected in verification and validation activities. As a minimum requirement, system designers require that HDL-programmed applications should be developed in accordance with system development life cycle and HPD design process. In the verification and validation processes, a review, test, and analysis activities should be properly conducted.
基金supported by the National Natural Science Foundation of China(Grant Nos.11172081 and 11372086)Shenzhen Research Innovation Fund,China(Grant No.JCYJ20120613150312764)
文摘In this paper,we analyze the stress and electric field intensity factors affected by residual surface stress for conducting cracks in piezoelectric nanomaterials.The problem is reduced to a system of non-linear singular integral equations,whose solution is determined by iteration technique.Numerical results indicate that the residual surface stress can significantly alter the crack tip fields at nanometer length scales.Due to the residual surface stress,281he electric field can produce stress around crack tip.This suggests a strong electromechanical coupling crack tip field for nanoscale piezoelectric materials.Such a finding is considerably different from the classical fracture mechanics results.A transit electric field to stress load ratio is identified,for which influences of residual surface stresses vanish.The research is useful for the applications of nanoscale piezoelectric devices.
