Amid urbanization and the continuous expansion of transportation networks,the necessity for tunnel construction and maintenance has become paramount.Addressing this need requires the investigation of efficient,economi...Amid urbanization and the continuous expansion of transportation networks,the necessity for tunnel construction and maintenance has become paramount.Addressing this need requires the investigation of efficient,economical,and robust tunnel reinforcement techniques.This paper explores fiber reinforced polymer(FRP)and steel fiber reinforced concrete(SFRC)technologies,which have emerged as viable solutions for enhancing tunnel structures.FRP is celebrated for its lightweight and high-strength attributes,effectively augmenting load-bearing capacity and seismic resistance,while SFRC’s notable crack resistance and longevity potentially enhance the performance of tunnel segments.Nonetheless,current research predominantly focuses on experimental analysis,lacking comprehensive theoretical models.To bridge this gap,the cohesive zone model(CZM),which utilizes cohesive elements to characterize the potential fracture surfaces of concrete/SFRC,the rebar-concrete interface,and the FRP-concrete interface,was employed.A modeling approach was subsequently proposed to construct a tunnel segment model reinforced with either SFRC or FRP.Moreover,the corresponding mixed-mode constitutive models,considering interfacial friction,were integrated into the proposed model.Experimental validation and numerical simulations corroborated the accuracy of the proposed model.Additionally,this study examined the reinforcement design of tunnel segments.Through a numerical evaluation,the effectiveness of innovative reinforcement schemes,such as substituting concrete with SFRC and externally bonding FRP sheets,was assessed utilizing a case study from the Fuzhou Metro Shield Tunnel Construction Project.展开更多
In this paper,the combustion process of oil shale semicoke was investigated by modeling,where intraparticle mass transfer resistance was especially considered.The ash formation and attrition characteristics of oil sha...In this paper,the combustion process of oil shale semicoke was investigated by modeling,where intraparticle mass transfer resistance was especially considered.The ash formation and attrition characteristics of oil shale semicoke were also investigated by a laboratory test procedure.The burnout time and residence time of different particle sizes were predicted,and the maximum particle size of which oil shale semicoke could be burned out in a 3 MW circulating fluidized bed boiler was obtained.展开更多
Diffusion of oxygen in the ash layer usually dominated the combustion of oil shale semicoke particles due to the high ash content.Thus,effective diffusivity of oxygen in the ash layer was a crucial parameter worthy of...Diffusion of oxygen in the ash layer usually dominated the combustion of oil shale semicoke particles due to the high ash content.Thus,effective diffusivity of oxygen in the ash layer was a crucial parameter worthy of careful investigation.In this paper,the effective diffusivity of oxygen in the ash layer of Huadian oil shale semicoke was measured directly using an improved Wicke-Kallenbach diffusion apparatus.The experimental results showed that higher temperature would lead to a higher effective diffusivity and a thicker ash layer had the negative effect.Especially,the effective diffusivity along the direction perpendicular to bedding planes was much lower than that along the direction parallel to bedding planes.In addition,an effective diffusivity model was developed,which could be used to describe the mass transfer of oxygen in the ash layer of oil shale semicoke.展开更多
Although the accomplishments of microbiome engineering highlight its significance for the targeted manipulation of microbial communities,knowledge and technical gaps still limit the applications of microbiome engineer...Although the accomplishments of microbiome engineering highlight its significance for the targeted manipulation of microbial communities,knowledge and technical gaps still limit the applications of microbiome engineering in biotechnology,especially for environmental use.Addressing the environmental challenges of refractory pollutants and fluctuating environmental conditions requires an adequate understanding of the theoretical achievements and practical applications of microbiome engineering.Here,we review recent cutting-edge studies on microbiome engineering strategies and their classical applications in bioremediation.Moreover,a framework is summarized for combining both top-down and bottom-up approaches in microbiome engineering toward improved applications.A strategy to engineer microbiomes for environmental use,which avoids the build-up of toxic intermediates that pose a risk to human health,is suggested.We anticipate that the highlighted framework and strategy will be beneficial for engineering microbiomes to address difficult environmental challenges such as degrading multiple refractory pollutants and sustain the performance of engineered microbiomes in situ with indigenous microorganisms under fluctuating conditions.展开更多
基金funded by the Scientific research startup Foundation of Fujian University of Technology(GY-Z21067 and GY-Z21026).
文摘Amid urbanization and the continuous expansion of transportation networks,the necessity for tunnel construction and maintenance has become paramount.Addressing this need requires the investigation of efficient,economical,and robust tunnel reinforcement techniques.This paper explores fiber reinforced polymer(FRP)and steel fiber reinforced concrete(SFRC)technologies,which have emerged as viable solutions for enhancing tunnel structures.FRP is celebrated for its lightweight and high-strength attributes,effectively augmenting load-bearing capacity and seismic resistance,while SFRC’s notable crack resistance and longevity potentially enhance the performance of tunnel segments.Nonetheless,current research predominantly focuses on experimental analysis,lacking comprehensive theoretical models.To bridge this gap,the cohesive zone model(CZM),which utilizes cohesive elements to characterize the potential fracture surfaces of concrete/SFRC,the rebar-concrete interface,and the FRP-concrete interface,was employed.A modeling approach was subsequently proposed to construct a tunnel segment model reinforced with either SFRC or FRP.Moreover,the corresponding mixed-mode constitutive models,considering interfacial friction,were integrated into the proposed model.Experimental validation and numerical simulations corroborated the accuracy of the proposed model.Additionally,this study examined the reinforcement design of tunnel segments.Through a numerical evaluation,the effectiveness of innovative reinforcement schemes,such as substituting concrete with SFRC and externally bonding FRP sheets,was assessed utilizing a case study from the Fuzhou Metro Shield Tunnel Construction Project.
基金the National Program on Key Basic Research Project(973 Program)of China(No.2014CB744305)is gratefully acknowledged.
文摘In this paper,the combustion process of oil shale semicoke was investigated by modeling,where intraparticle mass transfer resistance was especially considered.The ash formation and attrition characteristics of oil shale semicoke were also investigated by a laboratory test procedure.The burnout time and residence time of different particle sizes were predicted,and the maximum particle size of which oil shale semicoke could be burned out in a 3 MW circulating fluidized bed boiler was obtained.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.U1810126).
文摘Diffusion of oxygen in the ash layer usually dominated the combustion of oil shale semicoke particles due to the high ash content.Thus,effective diffusivity of oxygen in the ash layer was a crucial parameter worthy of careful investigation.In this paper,the effective diffusivity of oxygen in the ash layer of Huadian oil shale semicoke was measured directly using an improved Wicke-Kallenbach diffusion apparatus.The experimental results showed that higher temperature would lead to a higher effective diffusivity and a thicker ash layer had the negative effect.Especially,the effective diffusivity along the direction perpendicular to bedding planes was much lower than that along the direction parallel to bedding planes.In addition,an effective diffusivity model was developed,which could be used to describe the mass transfer of oxygen in the ash layer of oil shale semicoke.
基金the National Key R&D Program of China(2021YFA0910300)Shanghai Excellent Academic Leaders Program(20XD1421900)the National Natural Science Foundation of China(32100075 and 32030004)。
文摘Although the accomplishments of microbiome engineering highlight its significance for the targeted manipulation of microbial communities,knowledge and technical gaps still limit the applications of microbiome engineering in biotechnology,especially for environmental use.Addressing the environmental challenges of refractory pollutants and fluctuating environmental conditions requires an adequate understanding of the theoretical achievements and practical applications of microbiome engineering.Here,we review recent cutting-edge studies on microbiome engineering strategies and their classical applications in bioremediation.Moreover,a framework is summarized for combining both top-down and bottom-up approaches in microbiome engineering toward improved applications.A strategy to engineer microbiomes for environmental use,which avoids the build-up of toxic intermediates that pose a risk to human health,is suggested.We anticipate that the highlighted framework and strategy will be beneficial for engineering microbiomes to address difficult environmental challenges such as degrading multiple refractory pollutants and sustain the performance of engineered microbiomes in situ with indigenous microorganisms under fluctuating conditions.
