Corrosion in drinking water distribution systems(DWDSs)may lead to pipe failures and water quality deterioration;biocorrosion is the most common type.Chlorine disinfectants are widely used in DWDSs to inhibit microorg...Corrosion in drinking water distribution systems(DWDSs)may lead to pipe failures and water quality deterioration;biocorrosion is the most common type.Chlorine disinfectants are widely used in DWDSs to inhibit microorganism growth,but these also promote electrochemical corrosion to a certain extent.This study explored the independent and synergistic effects of chlorine and microorganisms on pipeline corrosion.Sodium hypochlorite(NaOCl)at different concentrations(0,0.25,0.50,and 0.75 mg/L)and iron-oxidizing bacteria(IOB)were added to the reaction system,and a biofilm annular reactor(BAR)was employed to simulate operational water supply pipes and explain the composite effects.The degree of corrosion became severe with increasing NaOCl dosage.IOB accelerated the corrosion rate at an early stage,after which the reaction system gradually stabilized.When NaOCl and IOB existed together in the BAR,both synergistic and antagonistic effects occurred during the corrosion process.The AOC content increased due to the addition of NaOCl,which is conducive to bacterial regrowth.However,biofilm on cast iron coupons was greatly influenced by the disinfectant,leading to a decrease in microbial biomass over time.More research is needed to provide guidelines for pipeline corrosion control.展开更多
Six thin sections of spheroidal graphites in cast iron have been investigated by TEM and SEM.The spheroidal graphites consist of two or three layers and have nuclei which are composed of Ce_2O_2S and Ce_2O_3. Cerium i...Six thin sections of spheroidal graphites in cast iron have been investigated by TEM and SEM.The spheroidal graphites consist of two or three layers and have nuclei which are composed of Ce_2O_2S and Ce_2O_3. Cerium is existed ont only in nuclei,but also in central layer and middle layer of graphite.展开更多
A specialised electrochemical measurement cell was plugged into a pilot water distribution system to simulate the pipe inner-wall corrosion. The linear polarisation resistance(LPR) technique and electrochemical impeda...A specialised electrochemical measurement cell was plugged into a pilot water distribution system to simulate the pipe inner-wall corrosion. The linear polarisation resistance(LPR) technique and electrochemical impedance spectroscopy(EIS) were measured in real time to study the variation of the corrosion rate(CR) and scale of cast iron. Three corrosion stages were observed according to the LPR analysis: an initial stage with significantly fluctuating CR, a developmental stage with slowly decreasing CR, and a stable stage with a low CR of approximately 0.157 5 mm·a^(-1). The EIS revealed that the scales with a compact outer layer and a porous inner layer finally formed in the stable stage, and the polarisation resistance was approximately 2 175 ?·cm^2. A physicochemical analysis of the scales showed that ferric oxides, oxyhydroxides and calcite made the outer layer compact and effectively limited the diffusion of oxygen through the scales, which resulted in a low CR.展开更多
Charge planning is one of batching problems for steelmaking and continuous casting production,and its optimization will be conducive to subsequent cast planning.Charge planning problem in the twin strands continuous c...Charge planning is one of batching problems for steelmaking and continuous casting production,and its optimization will be conducive to subsequent cast planning.Charge planning problem in the twin strands continuous casting production was studied,where casting width of the odd strand might be different from that of the even strand.Considering the different widths in the twin strands,the resulting counterweights and the constraints of steelmaking and continuous casting,a multiobjective optimization model was established to minimize the number of charges,the number of scale pairs,the surplus and the upgrading costs of steel grades.Furthermore,a hybrid optimization algorithm combined with heuristic and mutation-based estimation of distribution algorithm was proposed to solve the model.Experiments were conducted on several groups of test data collected from practical production orders of Baosteel.The computational results demonstrate that the proposed algorithm can generate better solutions than the manual method.The proposed model and algorithm proved to be effective and practical.展开更多
基金grateful for primary support from the National Natural Science Foundation of China(Grant No.51979194).
文摘Corrosion in drinking water distribution systems(DWDSs)may lead to pipe failures and water quality deterioration;biocorrosion is the most common type.Chlorine disinfectants are widely used in DWDSs to inhibit microorganism growth,but these also promote electrochemical corrosion to a certain extent.This study explored the independent and synergistic effects of chlorine and microorganisms on pipeline corrosion.Sodium hypochlorite(NaOCl)at different concentrations(0,0.25,0.50,and 0.75 mg/L)and iron-oxidizing bacteria(IOB)were added to the reaction system,and a biofilm annular reactor(BAR)was employed to simulate operational water supply pipes and explain the composite effects.The degree of corrosion became severe with increasing NaOCl dosage.IOB accelerated the corrosion rate at an early stage,after which the reaction system gradually stabilized.When NaOCl and IOB existed together in the BAR,both synergistic and antagonistic effects occurred during the corrosion process.The AOC content increased due to the addition of NaOCl,which is conducive to bacterial regrowth.However,biofilm on cast iron coupons was greatly influenced by the disinfectant,leading to a decrease in microbial biomass over time.More research is needed to provide guidelines for pipeline corrosion control.
文摘Six thin sections of spheroidal graphites in cast iron have been investigated by TEM and SEM.The spheroidal graphites consist of two or three layers and have nuclei which are composed of Ce_2O_2S and Ce_2O_3. Cerium is existed ont only in nuclei,but also in central layer and middle layer of graphite.
基金Supported by the National Natural Science Foundation of China(No.51278333)Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20130032110032)
文摘A specialised electrochemical measurement cell was plugged into a pilot water distribution system to simulate the pipe inner-wall corrosion. The linear polarisation resistance(LPR) technique and electrochemical impedance spectroscopy(EIS) were measured in real time to study the variation of the corrosion rate(CR) and scale of cast iron. Three corrosion stages were observed according to the LPR analysis: an initial stage with significantly fluctuating CR, a developmental stage with slowly decreasing CR, and a stable stage with a low CR of approximately 0.157 5 mm·a^(-1). The EIS revealed that the scales with a compact outer layer and a porous inner layer finally formed in the stable stage, and the polarisation resistance was approximately 2 175 ?·cm^2. A physicochemical analysis of the scales showed that ferric oxides, oxyhydroxides and calcite made the outer layer compact and effectively limited the diffusion of oxygen through the scales, which resulted in a low CR.
基金This work was supported by the National Key Research and Development Program of China(No.2017YFB0304100).
文摘Charge planning is one of batching problems for steelmaking and continuous casting production,and its optimization will be conducive to subsequent cast planning.Charge planning problem in the twin strands continuous casting production was studied,where casting width of the odd strand might be different from that of the even strand.Considering the different widths in the twin strands,the resulting counterweights and the constraints of steelmaking and continuous casting,a multiobjective optimization model was established to minimize the number of charges,the number of scale pairs,the surplus and the upgrading costs of steel grades.Furthermore,a hybrid optimization algorithm combined with heuristic and mutation-based estimation of distribution algorithm was proposed to solve the model.Experiments were conducted on several groups of test data collected from practical production orders of Baosteel.The computational results demonstrate that the proposed algorithm can generate better solutions than the manual method.The proposed model and algorithm proved to be effective and practical.
