Based on the biological resources surveys in China’s exclusive economic zone, the paper discusses the application of the GIS technology in evaluating the marine environmental quality, establishes the basic concept an...Based on the biological resources surveys in China’s exclusive economic zone, the paper discusses the application of the GIS technology in evaluating the marine environmental quality, establishes the basic concept and technological process for evaluating the environmental quality of the habitats of marine living resources, proposes the key points for the establishment of the relevant evaluation attributes database by applying the GIS technology and analyses several typical evaluation models and the data interpolation method for the model in GIS. Results show that the combination of the GIS technology with the quantitative evaluation model can be applied to the fast and accurate evaluation of the marine environmental quality.展开更多
Degradation of RC （reinforced concrete） in maritime structures has become a worldwide problem due to its excessive costs of maintenance, repair and replacement in addition to its environmental impacts and safety iss...Degradation of RC （reinforced concrete） in maritime structures has become a worldwide problem due to its excessive costs of maintenance, repair and replacement in addition to its environmental impacts and safety issues. Degradation of both concrete and steel which is the main reason of reduction in the service life of RC structures strongly depends on the diffusion process of moisture and aggressive species. In this paper, the major and popular mathematical models of diffusion process in concrete are surveyed and investigated. Predominantly in these models, the coefficient of chloride diffusion into the concrete is assumed to be constant. Whereas, experimental records indicate that diffusion coefficient is a function of time. Subsequently, data analysis and comparisons between the existing analytical models for predicting the diffusion coefficient with the existing experimental database are carried out in this study. Clearly, these comparisons reveal that there are gaps between the existing mathematical models and previously recorded experimental results. Perhaps, these gaps may be interpreted as influence of the other affecting parameters on the diffusion coefficient such as temperature, aggregate size and relative humidity in addition to the water cement ratio. Accordingly, the existing mathematical models are not adequate enough to predict the diffusion coefficient precisely and further studies need to be performed.展开更多
文摘Based on the biological resources surveys in China’s exclusive economic zone, the paper discusses the application of the GIS technology in evaluating the marine environmental quality, establishes the basic concept and technological process for evaluating the environmental quality of the habitats of marine living resources, proposes the key points for the establishment of the relevant evaluation attributes database by applying the GIS technology and analyses several typical evaluation models and the data interpolation method for the model in GIS. Results show that the combination of the GIS technology with the quantitative evaluation model can be applied to the fast and accurate evaluation of the marine environmental quality.
文摘Degradation of RC （reinforced concrete） in maritime structures has become a worldwide problem due to its excessive costs of maintenance, repair and replacement in addition to its environmental impacts and safety issues. Degradation of both concrete and steel which is the main reason of reduction in the service life of RC structures strongly depends on the diffusion process of moisture and aggressive species. In this paper, the major and popular mathematical models of diffusion process in concrete are surveyed and investigated. Predominantly in these models, the coefficient of chloride diffusion into the concrete is assumed to be constant. Whereas, experimental records indicate that diffusion coefficient is a function of time. Subsequently, data analysis and comparisons between the existing analytical models for predicting the diffusion coefficient with the existing experimental database are carried out in this study. Clearly, these comparisons reveal that there are gaps between the existing mathematical models and previously recorded experimental results. Perhaps, these gaps may be interpreted as influence of the other affecting parameters on the diffusion coefficient such as temperature, aggregate size and relative humidity in addition to the water cement ratio. Accordingly, the existing mathematical models are not adequate enough to predict the diffusion coefficient precisely and further studies need to be performed.
