城市洪涝灾害应急管理体系建设研究

洪涝灾害一直是城市所面对的重大威胁。由于气候变化和高速城市化等原因,我国城市尤其需要重视洪涝灾害的应对。大量案例和理论证明:面对洪涝灾害,仅仅依靠工程设施等技术手段是不够的,必须加强应急管理体系的建设。透过公共管理的视角,本文以危机管理的PPRR模型为框架,探讨洪涝灾害的预防、准备、应对以及恢复四个阶段所应采取的对策,由此构建一个科学、完整、严密的应急管理体系,并推动城市综合应急管理体系的建设。     

公共政策视角下的城市防灾减灾规划探讨——以消除传染病威胁为例

地震、洪水、泥石流等传统自然灾害凸显出城市防灾减灾规划的重要性和必要性.随着生物技术发展、病毒演进及全球化进程的加快,传染病等新型灾害对城市的威胁进一步扩大,现有防灾减灾规划有必要在深度和广度上进行进一步拓展.城市规划师应透过公共政策的视角,结合公共危机管理的理论和PPRR模型,在传染病灾害的预防、准备、应对和恢复四个...     

Optimization of a heavy-duty compression-ignition engine fueled with diesel and gasoline-like fuels

Optimal injection strategies for a heavy-duty compression-ignition engine fueled with diesel and gasoline-like fuels (#91 gasoline and E10) and operated under mid- and high-load conditions are investigated. A state-of-the-art engine CFD tool with detailed fuel chemistry was used to evaluate the engine performance and pollutant emissions. The CFD tools feature a recently developed efficient chemistry solver that allowed the optimization tasks to be completed in practical computer times. A Non-dominated Sorting Genetic Algorithm II (NSGA II) was coupled with the CFD tool to seek optimal combinations of injection system variables to achieve clean and efficient combustion. The optimization study identified several key parameters that influence engine performance. It was found that the fuel volatility and reactivity both play important roles at the mid-load condition, while the high-load condition is less sensitive to the fuel reactivity. However, high volatility fuels, such as gasoline and E10, were found to be beneficial to fuel economy at high-load. The study indicates that with an optimized injection system gasoline-like fuels are promising for heavy-duty CI engines due to their lower NOx and soot emissions and higher fuel economy compared to conventional diesel fuels. However, the high in-cylinder gas pressure rise rate associated with Partially Premixed Combustion of gasoline-like fuels can become problematic at high-load and the low-load operating limit is also a challenge. Potential solutions are discussed based on the present optimization results.