A stochastic finite element computational methodology for probabilistic durability assessment of deteriorating reinforced concrete（RC） bridges by considering the time-and space-dependent variabilities is presented.F...A stochastic finite element computational methodology for probabilistic durability assessment of deteriorating reinforced concrete（RC） bridges by considering the time-and space-dependent variabilities is presented.First,finite element analysis with a smeared cracking approach is implemented.The time-dependent bond-slip relationship between steel and concrete,and the stress-strain relationship of corroded steel bars are considered.Secondly,a stochastic finite element-based computational framework for reliability assessment of deteriorating RC bridges is proposed.The spatial and temporal variability of several parameters affecting the reliability of RC bridges is considered.Based on the data reported by several researchers and from field investigations,the Monte Carlo simulation is used to account for the uncertainties in various parameters,including local and general corrosion in rebars,concrete cover depth,surface chloride concentration,chloride diffusion coefficient,and corrosion rate.Finally,the proposed probabilistic durability assessment approach and framework are applied to evaluate the time-dependent reliability of a girder of a RC bridge located on the Tianjin Binhai New Area in China.展开更多
As resource scarcity, extreme climate change, and pollution levels increase, economic growth must rely on more environmentally friendly and efficient production processes, Fuel cells are an ideal alternative to intern...As resource scarcity, extreme climate change, and pollution levels increase, economic growth must rely on more environmentally friendly and efficient production processes, Fuel cells are an ideal alternative to internal combustion （IC） engines and boilers on the path to greener industries because of their high effi- ciency and environmentally friendly operation, However, as a new energy technology, significant market penetration of fuel cells has not yet been achieved, In this paper, we perform a techno-economic and environmental analysis of fuel cell systems using life cycle and value chain activities, First, we investigate the procedure of fuel cell development and identify what activities should he undertaken according to fuel cell life cycle activities, value chain activities, and end-user acceptance criteria, Next, we present a unified learning of the institutional barriers in fuel cell commercialization, The primary end-user accep- tance criteria are function, cost, and reliability; a fuel cell should outperform these criteria compared with its competitors, such as IC engines and batteries, to achieve a competitive advantage, The repair and maintenance costs of fuel cells （due to low reliability） can lead to a substantial cost increase and decrease in availability, which are the major factors for end-user acceptance, The fuel cell industry must face the challenge of how to overcome this reliability barrier, This paper provides a deeper insight into our work over the years on the main barriers to fuel cell commercialization, and discusses the potential pivotal role of fuel cells in a future low-carbon green economy, It also identifies the needs and points out some direc- tions for this future low-carbon economy, Green energy, supplied with fuel cells, is truly the business mode of the future, Striving for a more sustainable development of economic growth by adopting green public investments and implementing policy initiatives encourages environmentally responsible indus- trial investments.展开更多
This paper introduces a new technology of using ceramic coating on piston rings of an internal combustion engine, and the comparison of mechanical efficiency and performances of an actual engine before and after the a...This paper introduces a new technology of using ceramic coating on piston rings of an internal combustion engine, and the comparison of mechanical efficiency and performances of an actual engine before and after the application of ceramic coating on the piston rings. The experimental results show that the mechanical efficiency and power output are enhanced by 4% and 2.6%, respectively, with fuel consumption reduced by (2.9%.) Further studies on coating processing and coating materials as well as the reliability and durability will be of great significance in the application and popularization of the new technology.展开更多
基金The National Natural Science Foundation of China (No.50708065)the National High Technology Research and Development Program of China (863 Program) (No. 2007AA11Z113)Specialized Research Fund for the Doctoral Program of Higher Education (No. 20070056125)
文摘A stochastic finite element computational methodology for probabilistic durability assessment of deteriorating reinforced concrete（RC） bridges by considering the time-and space-dependent variabilities is presented.First,finite element analysis with a smeared cracking approach is implemented.The time-dependent bond-slip relationship between steel and concrete,and the stress-strain relationship of corroded steel bars are considered.Secondly,a stochastic finite element-based computational framework for reliability assessment of deteriorating RC bridges is proposed.The spatial and temporal variability of several parameters affecting the reliability of RC bridges is considered.Based on the data reported by several researchers and from field investigations,the Monte Carlo simulation is used to account for the uncertainties in various parameters,including local and general corrosion in rebars,concrete cover depth,surface chloride concentration,chloride diffusion coefficient,and corrosion rate.Finally,the proposed probabilistic durability assessment approach and framework are applied to evaluate the time-dependent reliability of a girder of a RC bridge located on the Tianjin Binhai New Area in China.
基金the Ministry of Economic Development and Trade of Government of Alberta for the Campus Alberta Innovation Program (CAIP) Research Chair (RCP-12-001BCAIP)
文摘As resource scarcity, extreme climate change, and pollution levels increase, economic growth must rely on more environmentally friendly and efficient production processes, Fuel cells are an ideal alternative to internal combustion （IC） engines and boilers on the path to greener industries because of their high effi- ciency and environmentally friendly operation, However, as a new energy technology, significant market penetration of fuel cells has not yet been achieved, In this paper, we perform a techno-economic and environmental analysis of fuel cell systems using life cycle and value chain activities, First, we investigate the procedure of fuel cell development and identify what activities should he undertaken according to fuel cell life cycle activities, value chain activities, and end-user acceptance criteria, Next, we present a unified learning of the institutional barriers in fuel cell commercialization, The primary end-user accep- tance criteria are function, cost, and reliability; a fuel cell should outperform these criteria compared with its competitors, such as IC engines and batteries, to achieve a competitive advantage, The repair and maintenance costs of fuel cells （due to low reliability） can lead to a substantial cost increase and decrease in availability, which are the major factors for end-user acceptance, The fuel cell industry must face the challenge of how to overcome this reliability barrier, This paper provides a deeper insight into our work over the years on the main barriers to fuel cell commercialization, and discusses the potential pivotal role of fuel cells in a future low-carbon green economy, It also identifies the needs and points out some direc- tions for this future low-carbon economy, Green energy, supplied with fuel cells, is truly the business mode of the future, Striving for a more sustainable development of economic growth by adopting green public investments and implementing policy initiatives encourages environmentally responsible indus- trial investments.
文摘This paper introduces a new technology of using ceramic coating on piston rings of an internal combustion engine, and the comparison of mechanical efficiency and performances of an actual engine before and after the application of ceramic coating on the piston rings. The experimental results show that the mechanical efficiency and power output are enhanced by 4% and 2.6%, respectively, with fuel consumption reduced by (2.9%.) Further studies on coating processing and coating materials as well as the reliability and durability will be of great significance in the application and popularization of the new technology.
