In many circumstances involving heat and mass transfer issues,it is considered impractical to measure the input flux and the resulting state distribution in the domain.Therefore,the need to develop techniques to provi...In many circumstances involving heat and mass transfer issues,it is considered impractical to measure the input flux and the resulting state distribution in the domain.Therefore,the need to develop techniques to provide solutions for such problems and estimate the inverse mass flux becomes imperative.Adaptive state estimator(ASE)is increasingly becoming a popular inverse estimation technique which resolves inverse problems by incorporating the semi-Markovian concept into a Bayesian estimation technique,thereby developing an inverse input and state estimator consisting of a bank of parallel adaptively weighted Kalman filters.The ASE is particularly designed for a system that encompasses independent unknowns and/or random switching of input and measurement biases.The present study describes the scheme to estimate the groundwater input contaminant flux and its transient distribution in a conjectural two-dimensional aquifer by means of ASE,which in particular is because of its unique ability to efficiently handle the process noise giving an estimation of keeping the relative error range within 10%in 2-dimensional problems.Numerical simulation results show that the proposed estimator presents decent estimation performance for both smoothly and abruptly varying input flux scenarios.Results also show that ASE enjoys a better estimation performance than its competitor,Recursive Least Square Estimator(RLSE)due to its larger error tolerance in greater process noise regimes.ASE's inherent deficiency of being slower than the RLSE,resulting from the complexity of algorithm,was also noticed.The chosen input scenarios are tested to calculate the effect of input area and both estimators show improved results with an increase in input flux area especially as sensors are moved closer to the assumed input location.展开更多
Bipolar electrochemistry is a high-throughput corrosion testing method capable of applying a quasi-linear potential gradient across test specimens.This study employs-bipolar electrochemistry corrosion testing to inves...Bipolar electrochemistry is a high-throughput corrosion testing method capable of applying a quasi-linear potential gradient across test specimens.This study employs-bipolar electrochemistry corrosion testing to investigate the influence of gravity on pitting corrosion of type 304L and 420 stainless steel across a broad range of applied potentials.Gravity modifies the distribution of current density on the bipolar electrode without altering the potential distribution.The impact of gravity on pitting corrosion is achieved through its effects on the dilution of the electrolyte and the removal of the salt film within the pits.Pits oriented in a face up position demonstrate smoother morphologies,larger cross-sectional areas and pit volumes.In contrast,pits oriented in perpendicular and facedown positions exhibit pit shape.Under conditions governed by diffusion and activation control,pits can up to over 100μm.Additionally,crystallographic pits are observed to form in areas subjected to high applied potentials.展开更多
文摘In many circumstances involving heat and mass transfer issues,it is considered impractical to measure the input flux and the resulting state distribution in the domain.Therefore,the need to develop techniques to provide solutions for such problems and estimate the inverse mass flux becomes imperative.Adaptive state estimator(ASE)is increasingly becoming a popular inverse estimation technique which resolves inverse problems by incorporating the semi-Markovian concept into a Bayesian estimation technique,thereby developing an inverse input and state estimator consisting of a bank of parallel adaptively weighted Kalman filters.The ASE is particularly designed for a system that encompasses independent unknowns and/or random switching of input and measurement biases.The present study describes the scheme to estimate the groundwater input contaminant flux and its transient distribution in a conjectural two-dimensional aquifer by means of ASE,which in particular is because of its unique ability to efficiently handle the process noise giving an estimation of keeping the relative error range within 10%in 2-dimensional problems.Numerical simulation results show that the proposed estimator presents decent estimation performance for both smoothly and abruptly varying input flux scenarios.Results also show that ASE enjoys a better estimation performance than its competitor,Recursive Least Square Estimator(RLSE)due to its larger error tolerance in greater process noise regimes.ASE's inherent deficiency of being slower than the RLSE,resulting from the complexity of algorithm,was also noticed.The chosen input scenarios are tested to calculate the effect of input area and both estimators show improved results with an increase in input flux area especially as sensors are moved closer to the assumed input location.
基金Science&Technology Fundamental resources investigation program(Grant No.2022FY101300)Guangdong Basic and Applied Basic Research Foundation(Grant 2023A1515110926).
文摘Bipolar electrochemistry is a high-throughput corrosion testing method capable of applying a quasi-linear potential gradient across test specimens.This study employs-bipolar electrochemistry corrosion testing to investigate the influence of gravity on pitting corrosion of type 304L and 420 stainless steel across a broad range of applied potentials.Gravity modifies the distribution of current density on the bipolar electrode without altering the potential distribution.The impact of gravity on pitting corrosion is achieved through its effects on the dilution of the electrolyte and the removal of the salt film within the pits.Pits oriented in a face up position demonstrate smoother morphologies,larger cross-sectional areas and pit volumes.In contrast,pits oriented in perpendicular and facedown positions exhibit pit shape.Under conditions governed by diffusion and activation control,pits can up to over 100μm.Additionally,crystallographic pits are observed to form in areas subjected to high applied potentials.
