【目的】研究铁山水库流域非点源污染负荷的空间分布规律及影响因素,为铁山水库流域水质保护与非点源污染控制提供参考。【方法】建立了铁山水库流域的水土评价模型(soil and water assessment tool,SWAT),并运用该模型研究了流域总氮...【目的】研究铁山水库流域非点源污染负荷的空间分布规律及影响因素,为铁山水库流域水质保护与非点源污染控制提供参考。【方法】建立了铁山水库流域的水土评价模型(soil and water assessment tool,SWAT),并运用该模型研究了流域总氮和总磷非点源污染排放强度与贡献率的空间分布特征及3种不同土地利用情景下非点源污染的变化情况。【结果】SWAT模型在模拟铁山水库流域水流和污染物运移过程方面精度良好。铁山水库流域非点源氮素主要来源于库区农田耕作过程中施加的化肥,而流域非点源磷素则主要来源于库区分散农村人口排放的生活污水及库区农田耕作过程中施加的化肥。流域非点源总氮和总磷污染负荷量在1995—2015年间分别下降了49.26%和86.66%。【结论】在流域内进行退耕还林及人口集中与外迁安置对流域非点源污染控制具有积极作用。展开更多
为探究粉葛(Pueraria montana var. thomsonii)对干旱胁迫的生理响应机制,本研究以粉葛植株为试验材料,通过盆栽形式和自然耗水与人工补水相结合的控水方法,分别设定了3个不同水分梯度。结果表明:干旱胁迫会抑制粉葛生长,叶片相对含水...为探究粉葛(Pueraria montana var. thomsonii)对干旱胁迫的生理响应机制,本研究以粉葛植株为试验材料,通过盆栽形式和自然耗水与人工补水相结合的控水方法,分别设定了3个不同水分梯度。结果表明:干旱胁迫会抑制粉葛生长,叶片相对含水量和根系活力降低,叶绿素总含量显著增加;超氧化物歧化酶(SOD)和过氧化物酶(POD)酶活性均得到提高,过氧化氢酶(CAT)酶活性在中度干旱胁迫下逐渐增加,重度干旱胁迫下CAT酶活性逐渐降低;叶肉细胞相对电导率显著增加,渗透调节物质浓度增加;总黄酮含量显著升高。单叶面积与POD、叶绿素a、叶绿素b、总叶绿素含量和可溶性蛋白含量呈现显著负相关,POD和脯氨酸与总黄酮含量显著正相关。通过相关性分析与主成分分析可知,POD、相对含水量、SOD、类胡萝卜素、可溶性蛋白、CAT和总黄酮在干旱胁迫下表现为较敏感的生理指标。本研究结果可为粉葛节水及优质栽培的生理机制提供理论基础。展开更多
In the present study, a novel model is proposed to evaluate the lower flammability limit(LFL) of alkane diluted with CO2. The LFL model is based on flame phenomenon simulation(FS-LFL). The model consists of combustion...In the present study, a novel model is proposed to evaluate the lower flammability limit(LFL) of alkane diluted with CO2. The LFL model is based on flame phenomenon simulation(FS-LFL). The model consists of combustion, turbulence, and igniter models, which are used to characterise the combustion based on the chemical kinetics and CFD, which is not feasible with traditional methods. The flame simulation phenomenon was validated by contrast with experiment and same criterion of flammability limit in the experiment was adopted. The FS-LFL model was used to predict the LFLs of a propane-CO2 mixture and propane at various temperatures. The model performance was analysed by comparing the results with experimental data and predictions obtained from existing methods. The AARDs between the predicted and experimentally determined LFLs of the propane-CO2 mixture are 0.34%, 1.19%, and 1.35% at 30℃, 50℃, and 70℃, respectively. The model also has a good predictive power with respect to the LFLs of propane at initial temperatures ranging from 30℃–300℃, with an AARD of 2.10%. When the dilution of CO2 is 90%, the model yields a better result due to the utilisation of the chemical kinetics mechanism. This result is instructive for the use of this method in the prediction of upper flammability limits.展开更多
As group contribution method is easy to apply and has a wide application range,current study has developed this model to predict flammability limit of hydrocarbons mixed with inert gas using the Marrero/Gani group con...As group contribution method is easy to apply and has a wide application range,current study has developed this model to predict flammability limit of hydrocarbons mixed with inert gas using the Marrero/Gani group contribution method,which is significative to the safe application of hydrocarbons in the ORC system.The whole modeling process is divided into two parts:pure compound prediction and mixture prediction.The contribution factors of inert gases and dilute concentration were first introduced in the group contribution method.Moreover,the respective 95%-confidence interval of the mixture based on linear superposition method has been proposed in the developed group contribution model to improve the safety coefficient.For CO2 as inert gas,the average relative error and correlation coefficient are 5.34%and 0.88 for lower flammability limit while 6.99%and 0.95 for upper flammability limit.For N2 as inert gas,the average relative error and correlation coefficient are 7.47%and 0.84 for lower flammability limit while 6.68%and 0.97 for upper flammability limit.Most importantly,this group contribution method has extended the application range to make up the shortcomings of other flammability limit prediction methods aiming at hydrocarbon and inert gas mixtures and proposed the uncertainty analysis to provide reliable prediction range.展开更多
文摘【目的】研究铁山水库流域非点源污染负荷的空间分布规律及影响因素,为铁山水库流域水质保护与非点源污染控制提供参考。【方法】建立了铁山水库流域的水土评价模型(soil and water assessment tool,SWAT),并运用该模型研究了流域总氮和总磷非点源污染排放强度与贡献率的空间分布特征及3种不同土地利用情景下非点源污染的变化情况。【结果】SWAT模型在模拟铁山水库流域水流和污染物运移过程方面精度良好。铁山水库流域非点源氮素主要来源于库区农田耕作过程中施加的化肥,而流域非点源磷素则主要来源于库区分散农村人口排放的生活污水及库区农田耕作过程中施加的化肥。流域非点源总氮和总磷污染负荷量在1995—2015年间分别下降了49.26%和86.66%。【结论】在流域内进行退耕还林及人口集中与外迁安置对流域非点源污染控制具有积极作用。
文摘为探究粉葛(Pueraria montana var. thomsonii)对干旱胁迫的生理响应机制,本研究以粉葛植株为试验材料,通过盆栽形式和自然耗水与人工补水相结合的控水方法,分别设定了3个不同水分梯度。结果表明:干旱胁迫会抑制粉葛生长,叶片相对含水量和根系活力降低,叶绿素总含量显著增加;超氧化物歧化酶(SOD)和过氧化物酶(POD)酶活性均得到提高,过氧化氢酶(CAT)酶活性在中度干旱胁迫下逐渐增加,重度干旱胁迫下CAT酶活性逐渐降低;叶肉细胞相对电导率显著增加,渗透调节物质浓度增加;总黄酮含量显著升高。单叶面积与POD、叶绿素a、叶绿素b、总叶绿素含量和可溶性蛋白含量呈现显著负相关,POD和脯氨酸与总黄酮含量显著正相关。通过相关性分析与主成分分析可知,POD、相对含水量、SOD、类胡萝卜素、可溶性蛋白、CAT和总黄酮在干旱胁迫下表现为较敏感的生理指标。本研究结果可为粉葛节水及优质栽培的生理机制提供理论基础。
基金supported by the National Natural Science Foundation of China (Grant No. 51676133)。
文摘In the present study, a novel model is proposed to evaluate the lower flammability limit(LFL) of alkane diluted with CO2. The LFL model is based on flame phenomenon simulation(FS-LFL). The model consists of combustion, turbulence, and igniter models, which are used to characterise the combustion based on the chemical kinetics and CFD, which is not feasible with traditional methods. The flame simulation phenomenon was validated by contrast with experiment and same criterion of flammability limit in the experiment was adopted. The FS-LFL model was used to predict the LFLs of a propane-CO2 mixture and propane at various temperatures. The model performance was analysed by comparing the results with experimental data and predictions obtained from existing methods. The AARDs between the predicted and experimentally determined LFLs of the propane-CO2 mixture are 0.34%, 1.19%, and 1.35% at 30℃, 50℃, and 70℃, respectively. The model also has a good predictive power with respect to the LFLs of propane at initial temperatures ranging from 30℃–300℃, with an AARD of 2.10%. When the dilution of CO2 is 90%, the model yields a better result due to the utilisation of the chemical kinetics mechanism. This result is instructive for the use of this method in the prediction of upper flammability limits.
基金This work was supported by a grant from the National Natural Science Foundation of China(No.51676133)。
文摘As group contribution method is easy to apply and has a wide application range,current study has developed this model to predict flammability limit of hydrocarbons mixed with inert gas using the Marrero/Gani group contribution method,which is significative to the safe application of hydrocarbons in the ORC system.The whole modeling process is divided into two parts:pure compound prediction and mixture prediction.The contribution factors of inert gases and dilute concentration were first introduced in the group contribution method.Moreover,the respective 95%-confidence interval of the mixture based on linear superposition method has been proposed in the developed group contribution model to improve the safety coefficient.For CO2 as inert gas,the average relative error and correlation coefficient are 5.34%and 0.88 for lower flammability limit while 6.99%and 0.95 for upper flammability limit.For N2 as inert gas,the average relative error and correlation coefficient are 7.47%and 0.84 for lower flammability limit while 6.68%and 0.97 for upper flammability limit.Most importantly,this group contribution method has extended the application range to make up the shortcomings of other flammability limit prediction methods aiming at hydrocarbon and inert gas mixtures and proposed the uncertainty analysis to provide reliable prediction range.
