The filling and solidification of a malleable iron pipe casting manufactured by DISA casting mold line with different design parameters were calculated by using software MAGMASOFT. Then the shrinkage porosity was pred...The filling and solidification of a malleable iron pipe casting manufactured by DISA casting mold line with different design parameters were calculated by using software MAGMASOFT. Then the shrinkage porosity was predicted by thermal criterion. Based on the simulation results, the influences of the runner ratio and feeder position on the porosity were discussed. The results show that synchronization of injection can be significantly influenced by the size of downsprue section, and an de-sign structure of DISA gating system was used to solve the problem of flow imbalance in the filling procegs. At the same time, the riser was designed on the hotspot for feeding shrinkage. At last, the optimizated gating system and feeding system were ac-complished to eliminate shrinkage porosity.展开更多
A special polyurethane coating designed for ductile iron pipe was developed. The effects of the ingredients on properties, such as viscosity, flow leveling, solidification-rate, adhesion and hardness, were researched....A special polyurethane coating designed for ductile iron pipe was developed. The effects of the ingredients on properties, such as viscosity, flow leveling, solidification-rate, adhesion and hardness, were researched. It was then analyzed in what ways the technical parameters, such as temperature and pressure, influence the coat quality. The results showed that the molar ratio and synthesizing conditions must be strictly controlled to obtain suitable pre-polymer viscosity by adjusting the formula ratio of the B component, satisfactory mechanical properties and cure rate can be obtained and bubbles in the coat can be avoided.展开更多
In this study, a new method is proposed to evaluate the seismic behavior of buried jointed water pipeline networks subjected to wave propagation. First, using finite element method and solid elements, different kinds ...In this study, a new method is proposed to evaluate the seismic behavior of buried jointed water pipeline networks subjected to wave propagation. First, using finite element method and solid elements, different kinds of currently used connections in the network are modeled, and their nonlinear behavior in all directions is obtained. Second, a 950-meter long network consisting of ductile iron pipes segments of 6-meter length and springs characterizing the connections, are modeled using beam elements. Three-component displacement record of the Tabas earthquake is applied to the network considering the time lag between support inputs, and the nonlinear soil-pipe interaction. The record is applied once in North-South direction and once in East-West direction with different wave propagation velocities. Results of interest such as stress values and rotations at various points of the network are then obtained, and critical points are introduced in each direction. Results show that the points other than the critical ones at the network intersections remain elastic.展开更多
The effects of cast iron pipe corrosion onwater quality risk and microbial ecology in drinking water distribution systems(DWDSs)were investigated.It was found that trihalomethane(THMs)concentration and antibiotic resi...The effects of cast iron pipe corrosion onwater quality risk and microbial ecology in drinking water distribution systems(DWDSs)were investigated.It was found that trihalomethane(THMs)concentration and antibiotic resistance genes(ARGs)increased sharply in the old DWDSs.Under the same residual chlorine concentration conditions,the adenosine triphos-phate concentration in the effluent of old DWDSs(Eff-old)was significantly higher than that in the effluent of newDWDSs.Moreover,stronger bioflocculation ability andweaker hy-drophobicity coexisted in the extracellular polymeric substances of Eff-old,meanwhile,iron particles could be well inserted into the structure of the biofilms to enhance the mechanical strength and stability of the biofilms,hence enhancing the formation of THMs.Old DWDSs significantly influenced the microbial community of bulk water and triggered stronger mi-crobial antioxidant systems response,resulting in higher ARGs abundance.Corroded cast iron pipes induced a unique interaction system of biofilms,chlorine,and corrosion prod-ucts.Therefore,as the age of cast iron pipes increases,the fluctuation of water quality and microbial ecology should be paid more attention to maintain the safety of tap water.展开更多
文摘The filling and solidification of a malleable iron pipe casting manufactured by DISA casting mold line with different design parameters were calculated by using software MAGMASOFT. Then the shrinkage porosity was predicted by thermal criterion. Based on the simulation results, the influences of the runner ratio and feeder position on the porosity were discussed. The results show that synchronization of injection can be significantly influenced by the size of downsprue section, and an de-sign structure of DISA gating system was used to solve the problem of flow imbalance in the filling procegs. At the same time, the riser was designed on the hotspot for feeding shrinkage. At last, the optimizated gating system and feeding system were ac-complished to eliminate shrinkage porosity.
文摘A special polyurethane coating designed for ductile iron pipe was developed. The effects of the ingredients on properties, such as viscosity, flow leveling, solidification-rate, adhesion and hardness, were researched. It was then analyzed in what ways the technical parameters, such as temperature and pressure, influence the coat quality. The results showed that the molar ratio and synthesizing conditions must be strictly controlled to obtain suitable pre-polymer viscosity by adjusting the formula ratio of the B component, satisfactory mechanical properties and cure rate can be obtained and bubbles in the coat can be avoided.
文摘In this study, a new method is proposed to evaluate the seismic behavior of buried jointed water pipeline networks subjected to wave propagation. First, using finite element method and solid elements, different kinds of currently used connections in the network are modeled, and their nonlinear behavior in all directions is obtained. Second, a 950-meter long network consisting of ductile iron pipes segments of 6-meter length and springs characterizing the connections, are modeled using beam elements. Three-component displacement record of the Tabas earthquake is applied to the network considering the time lag between support inputs, and the nonlinear soil-pipe interaction. The record is applied once in North-South direction and once in East-West direction with different wave propagation velocities. Results of interest such as stress values and rotations at various points of the network are then obtained, and critical points are introduced in each direction. Results show that the points other than the critical ones at the network intersections remain elastic.
基金supported by the National Natural Science Foundation of China(Nos.52000043,and 51838005)the intro-duced innovative R&D team project under the“The Pearl River Talent Recruitment Program”of Guangdong Province(No.2019ZT08L387)+2 种基金the Guangdong Natural Science Foundation(No.2023A1515011509)the Science and Technology Research Project of Guangzhou(Nos.202201020177,202102020986 and 202102021044)the special fund from Key Laboratory of Drinking Water Science and Technology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences(No.20K01KLDWST).
文摘The effects of cast iron pipe corrosion onwater quality risk and microbial ecology in drinking water distribution systems(DWDSs)were investigated.It was found that trihalomethane(THMs)concentration and antibiotic resistance genes(ARGs)increased sharply in the old DWDSs.Under the same residual chlorine concentration conditions,the adenosine triphos-phate concentration in the effluent of old DWDSs(Eff-old)was significantly higher than that in the effluent of newDWDSs.Moreover,stronger bioflocculation ability andweaker hy-drophobicity coexisted in the extracellular polymeric substances of Eff-old,meanwhile,iron particles could be well inserted into the structure of the biofilms to enhance the mechanical strength and stability of the biofilms,hence enhancing the formation of THMs.Old DWDSs significantly influenced the microbial community of bulk water and triggered stronger mi-crobial antioxidant systems response,resulting in higher ARGs abundance.Corroded cast iron pipes induced a unique interaction system of biofilms,chlorine,and corrosion prod-ucts.Therefore,as the age of cast iron pipes increases,the fluctuation of water quality and microbial ecology should be paid more attention to maintain the safety of tap water.
