In district heating(DH) system with gas-fired peak load regulating boiler in the secondary network,by prolonging run time of base load plants under rated condition,the mean energy efficiency could be increased. The fu...In district heating(DH) system with gas-fired peak load regulating boiler in the secondary network,by prolonging run time of base load plants under rated condition,the mean energy efficiency could be increased. The fuels of the system,including coal and gas,would cause different environmental impacts. Meanwhile,the reliability of the heating networks would be changed because the peak load regulating boiler could work as a standby heat source. A model for assessment of heating system was established by value analysis to optimize this kind of system. Energy consumption,greenhouse gas emission,pollution emission and system reliability were selected as functional assessment indexes in the model. Weights of each function were determined by analytical hierarchy process (AHP) and experts consultation. Life cycle cost was used as the cost in the model. A real case as an example was discussed to obtain the optimal base load ratio. The result shows that the optimal base load ratio of the case is 0.77.展开更多
灌区水网包括一维河/渠/沟网和二维农田,其水动力过程在众多闸/坝/泵等复杂调控组合下呈现出典型的跨维度特征,导致难以采用经典耦合方法开展相关动力学模拟与分析。为此,本文对灌区一维河/渠/沟网和二维农田进行统一网格离散,把闸/坝/...灌区水网包括一维河/渠/沟网和二维农田,其水动力过程在众多闸/坝/泵等复杂调控组合下呈现出典型的跨维度特征,导致难以采用经典耦合方法开展相关动力学模拟与分析。为此,本文对灌区一维河/渠/沟网和二维农田进行统一网格离散,把闸/坝/泵等调控工程作为内边界条件,在势能梯度驱动下进行统一数学表征,通过水扩散系数来区分水运动所处的具体区域,构建了灌区水网动力学统一表征模型SkyHydid。采用黑龙江省青龙山灌区北片灌域渠网-农田的实测数据,验证该统一表征方法的计算性能。结果表明,模拟与实测的稻田积水深度及渠道水深过程之间的平均相对误差小于5%,模拟的渠道流量值与采用ADCP(Acoustic Doppler Current Profiler)实测的流量值之间的平均相对误差小于5%,说明构建的灌区水网动力学统一表征模型SkyHydid能较好的重现渠网和农田水动力过程,为灌区水网模拟与分析提供了可用工具。展开更多
As the greenway construction grows popular,the concept and type of greenway is clarified in this study,research progresses and prospects of greenway planning are summarized.Greenway planning of Shunde District is take...As the greenway construction grows popular,the concept and type of greenway is clarified in this study,research progresses and prospects of greenway planning are summarized.Greenway planning of Shunde District is taken for an example to elaborate properties,types,origination and tasks of greenway,moreover,construction background,ecological,human-centered and characteristic design principles were analyzed,especially the design of its buffer zone,corridor system,width of crawl lane,node system,identification system and service area.Greenway construction of Shunde District is to build a greenway network of multiple types and functions in 3 levels:region,city and community;a recreational landscaping system with regional greenland as the background,greennet and greenway as the framework,to promote a new "ecological,green and low-carbon" lifestyle,and create the new image of Shunde as "a livable riverfront region full of sunshine".展开更多
Groundwater environment evolution can comprehensively reflect groundwater dynamics. Based on the relationship between the groundwater system and the external environment in Jinghuiqu irrigation district, adopting the ...Groundwater environment evolution can comprehensively reflect groundwater dynamics. Based on the relationship between the groundwater system and the external environment in Jinghuiqu irrigation district, adopting the Principal Component Analysis method, variation characteristics of environmental factors including climate and human activity and their impact on groundwater were systematically analyzed. The results show that groundwater level in Jinghuiqu irrigation district has been significantly dropped in nearly 34 years;the reduction of surface water irrigation use, which reduced the amounts of groundwater recharge and destroyed the water balance, is considered as the most direct cause for falling of regional groundwater level. Besides, reduction in precipitation, increase of evaporation also accelerated the declining of the groundwater level at some extent. Finally, a predicting method of groundwater depth based on BP neural network is developed. The experimental results show that the predicting model can reasonablely predict the groundwater level in Jinghuiqu irrigation district with a high precision.展开更多
文摘In district heating(DH) system with gas-fired peak load regulating boiler in the secondary network,by prolonging run time of base load plants under rated condition,the mean energy efficiency could be increased. The fuels of the system,including coal and gas,would cause different environmental impacts. Meanwhile,the reliability of the heating networks would be changed because the peak load regulating boiler could work as a standby heat source. A model for assessment of heating system was established by value analysis to optimize this kind of system. Energy consumption,greenhouse gas emission,pollution emission and system reliability were selected as functional assessment indexes in the model. Weights of each function were determined by analytical hierarchy process (AHP) and experts consultation. Life cycle cost was used as the cost in the model. A real case as an example was discussed to obtain the optimal base load ratio. The result shows that the optimal base load ratio of the case is 0.77.
文摘灌区水网包括一维河/渠/沟网和二维农田,其水动力过程在众多闸/坝/泵等复杂调控组合下呈现出典型的跨维度特征,导致难以采用经典耦合方法开展相关动力学模拟与分析。为此,本文对灌区一维河/渠/沟网和二维农田进行统一网格离散,把闸/坝/泵等调控工程作为内边界条件,在势能梯度驱动下进行统一数学表征,通过水扩散系数来区分水运动所处的具体区域,构建了灌区水网动力学统一表征模型SkyHydid。采用黑龙江省青龙山灌区北片灌域渠网-农田的实测数据,验证该统一表征方法的计算性能。结果表明,模拟与实测的稻田积水深度及渠道水深过程之间的平均相对误差小于5%,模拟的渠道流量值与采用ADCP(Acoustic Doppler Current Profiler)实测的流量值之间的平均相对误差小于5%,说明构建的灌区水网动力学统一表征模型SkyHydid能较好的重现渠网和农田水动力过程,为灌区水网模拟与分析提供了可用工具。
文摘As the greenway construction grows popular,the concept and type of greenway is clarified in this study,research progresses and prospects of greenway planning are summarized.Greenway planning of Shunde District is taken for an example to elaborate properties,types,origination and tasks of greenway,moreover,construction background,ecological,human-centered and characteristic design principles were analyzed,especially the design of its buffer zone,corridor system,width of crawl lane,node system,identification system and service area.Greenway construction of Shunde District is to build a greenway network of multiple types and functions in 3 levels:region,city and community;a recreational landscaping system with regional greenland as the background,greennet and greenway as the framework,to promote a new "ecological,green and low-carbon" lifestyle,and create the new image of Shunde as "a livable riverfront region full of sunshine".
文摘Groundwater environment evolution can comprehensively reflect groundwater dynamics. Based on the relationship between the groundwater system and the external environment in Jinghuiqu irrigation district, adopting the Principal Component Analysis method, variation characteristics of environmental factors including climate and human activity and their impact on groundwater were systematically analyzed. The results show that groundwater level in Jinghuiqu irrigation district has been significantly dropped in nearly 34 years;the reduction of surface water irrigation use, which reduced the amounts of groundwater recharge and destroyed the water balance, is considered as the most direct cause for falling of regional groundwater level. Besides, reduction in precipitation, increase of evaporation also accelerated the declining of the groundwater level at some extent. Finally, a predicting method of groundwater depth based on BP neural network is developed. The experimental results show that the predicting model can reasonablely predict the groundwater level in Jinghuiqu irrigation district with a high precision.
