The basic equations for computing the volume of gas storage tank were derived from the principles of attenuating water hammer pressure. Verifications using experiments indicate that the proposed equation can provide a...The basic equations for computing the volume of gas storage tank were derived from the principles of attenuating water hammer pressure. Verifications using experiments indicate that the proposed equation can provide a fare precision in the predictions. By using the model of solid liquid two phase flow, the gas storage tank, pressure relief valves and slow closure reverse control valves were compared with practical engineering problems, and the functions of gas storage tank in attenuating water hammer pressure were further investigated. [展开更多
To obtain carbon dioxide (CO2) flux between water-air interface of Taihu lake, monthly water samplers at 14 sites and the local meteorological data of the lake were collected and analyzed in 1998. Carbon dioxide parti...To obtain carbon dioxide (CO2) flux between water-air interface of Taihu lake, monthly water samplers at 14 sites and the local meteorological data of the lake were collected and analyzed in 1998. Carbon dioxide partial pressures (pCO2) at air-water interface in the lake were calculated using alkalinity, pH, ionic strength, active coefficient, and water temperature. The carbon fluxes at different sublakes and areas were estimated by concentration gradient between water and air in consideration of Schmidt numbers of 600 and daily mean windspeed at 10 m above water surface. The results indicated that the mean values of pCO2 in Wuli Lake, Meiliang Bay, hydrophyte area, west littoral zone, riverine mouths, and the open lake areas were 1 807.8±1 071.4 (mean±standard deviation) μatm (1atm=1.013 25×105Pa), 416.3±217.0 μatm, 576.5±758.8 μatm, 304.2±243.5 μatm, 1 933.6±1 144.7 μatm, and 448.5±202.6 μatm, respectively. Maximum and minimum pCO2 values were found in the hypertrophic (4 053.7 μatm) and the eutrophic (3.2 μatm) areas. The riverine mouth areas have the maximum fluxes (82.0±62.8 mmol/m2a). But there was no significant difference between eutrophic and mesot- rophic areas in pCO2 and the flux of CO2. The hydrophyte area, however, has the minimum (-0.58±12.9 mmol/m2a). In respect to CO2 equilibrium, input of the rivers will obviously influence inorganic carbon distribu- tion in the riverine estuary. For example, the annual mean CO2 flux in Zhihugang River estuary was 19 times of that in Meiliang Bay, although the former is only a part of the latter. The sites in the body of the lake show a clear seasonal cycle with pCO2 higher than atmospheric equilibrium in winter, and much lower than atmospheric in summer due to CO2 consumption by photosynthesis. The CO2 amount of the net annual evasion that enters the atmosphere is 28.42×104 t/a, of which those from the west littoral zone and the open lake account for 53.8% and 36.7%, respectively.展开更多
As the performance of an air-cooled condenser is apt to be affected by the fluctuating ambient condition, some difficulties are brought to the use of a steam feeding water pump in an air-cooled unit. This paper introd...As the performance of an air-cooled condenser is apt to be affected by the fluctuating ambient condition, some difficulties are brought to the use of a steam feeding water pump in an air-cooled unit. This paper introduces a new design of for steam feeding the water pump of an air-cooled unit using the back-pressure steam turbine as the prime motor. Using variable condition analysis on a 600 MW direct air-cooled unit, and with consideration of the effect on the ambient conditions, the feasibility, economy, and adaptability of the design are verified.展开更多
Oscillating Water Column (OWC) wave energy converting system is one of the most widely used facilities all over the world. The air chamber is utilized to convert the wave energy into the pneumatic energy. The numeri...Oscillating Water Column (OWC) wave energy converting system is one of the most widely used facilities all over the world. The air chamber is utilized to convert the wave energy into the pneumatic energy. The numerical wave tank based on the two-phase VOF model is established in the present study toinvestigate the operating performance of OWC air chamber. The RANS equations, standard k-ε turbulence model and dynamic mesh technology are employed in the numerical model. The effects of incident wave conditions and shape parameters on the wave energy converting efficiency are studied and the capability of the present numerical wave tank on the corresponding engineering application is validated.展开更多
The stable operation of the central air conditioning water system always is a major difficulty for the control profession. Paper focus on the water system with multi variable, strong coupling, nonlinear, large time de...The stable operation of the central air conditioning water system always is a major difficulty for the control profession. Paper focus on the water system with multi variable, strong coupling, nonlinear, large time delay characteristics, presented use feed forward coupling compensation method, to eliminate the coupling effect between temperature and pressure. In this paper, the Elman neural network controller is designed for the first time, and the simulation results show that the response time of Elman neural network controller is shorter, the system is more stable and the overshoot is small.展开更多
In order to simulate the airflow in anhydrous case and the water-air flow in groundwater case, a numerical model of airflow in soil was developed. For the nonlinearity of the governing partial differential equation, t...In order to simulate the airflow in anhydrous case and the water-air flow in groundwater case, a numerical model of airflow in soil was developed. For the nonlinearity of the governing partial differential equation, the corresponding discretization and linearization methods were given. Due to the mass transfer between air-phase and water-phase, phase states of the model elements were constantly changing. Thus, parameters of the model were divided into primary ones and secondary ones, and the primary variables changing with phase states and the secondary variables can be obtained by their functional relationship with the primary variables. Additionally, the special definite condition of this numerical model was illustrated. Two examples were given to simulate the airflow in soil whether there was groundwater or not, and the effectiveness of the numerical model is verified by comparing the results of simulation with that of experiment.展开更多
Sagarmatha (Mt. Everest) National Park (SNP) of Nepal is a popular international eco-touristic destination. In the last few years, tourist flow has increased tremendously generating anthropogenic pressure on natural e...Sagarmatha (Mt. Everest) National Park (SNP) of Nepal is a popular international eco-touristic destination. In the last few years, tourist flow has increased tremendously generating anthropogenic pressure on natural environment. Generation of huge solid waste, open defecation and poor septic tank condition of toilets have been considered as the major sources of pollution to water bodies in the area. Heavy metals, such as cadmium, copper, lead, chromium and mercury, are important environmental pollutants, particularly in areas with high anthropogenic pressure. Their presence in the atmosphere, soil and water, even in traces can cause serious problems to all organisms, and heavy metal bioaccumulation in the food chain especially can be highly dangerous to human health. Heavy metals (Cu, Pb, Mn, Fe and Zn) and metals (Na, Mg) were analyzed. Thirty nine (13 samples in each year) water samples were collected from river and springs to assess the water quality in the SNP and its buffer zone. Water quality in the SNP has been found degraded in terms of heavy metals;particularly Na and Mg contents were found higher when compared with the earlier report. Iron content in 46% samples was found more than WHO and Nepalese standard for drinking water. The river water quality in general still stands good in terms of standard for drinking water (WHO, Nepal standard) however degradation process has accelerated.展开更多
结合长距离无压引水隧洞充水过程,建立了水气两相流耦合VOF(Volume of Fluid)法的k-ε紊流模型,近壁面采用考虑糙率影响的壁面函数,结合实际工程对长距离无压引水隧洞水气两相流进行了模拟。模拟结果表明:隧洞内水位随充水时间的增加逐...结合长距离无压引水隧洞充水过程,建立了水气两相流耦合VOF(Volume of Fluid)法的k-ε紊流模型,近壁面采用考虑糙率影响的壁面函数,结合实际工程对长距离无压引水隧洞水气两相流进行了模拟。模拟结果表明:隧洞内水位随充水时间的增加逐渐上升并趋于稳定;对隧洞充水过程中沿程典型断面的水气两相流进行了动态分析,结果表明进口流量为65 m3/s时水流能顺利通过隧洞;对某水库放水兼放空洞水深实测数据进行了验证对比,模拟结果与实验结果基本吻合。展开更多
【目的】探究马铃薯的叶气温差与环境因子的关系,进一步优化马铃薯水分胁迫指数模型。【方法】在河南农业大学林学院试验基地进行马铃薯盆栽试验,选择晴朗天气测定不同土壤含水率下马铃薯的叶气温差随太阳辐射和大气饱和水汽压差(VPD)...【目的】探究马铃薯的叶气温差与环境因子的关系,进一步优化马铃薯水分胁迫指数模型。【方法】在河南农业大学林学院试验基地进行马铃薯盆栽试验,选择晴朗天气测定不同土壤含水率下马铃薯的叶气温差随太阳辐射和大气饱和水汽压差(VPD)的变化规律,确定作物水分胁迫指数(crop water stress index,CWSI)的上下基线,进一步试验后得到优化后的马铃薯CWSI经验模型,并对相关模型进行验证。【结果】马铃薯的叶气温差随着土壤含水率的降低而升高;当土壤含水率较低(7.28%)时,马铃薯的叶气温差随太阳辐射的增大而增大,呈显著线性关系;当土壤含水率较高(15.85%)时,马铃薯的叶气温差随VPD的增大而减小,呈显著线性关系;构建出马铃薯CWSI的上基线为y=0.0098Q-0.68[Q为太阳辐射强度/(W·m^(-2))],下基线为y=-1.67V+3.75(V为大气饱和水汽压差/kPa);将优化的CWSI模型验证后得知,随着土壤含水率的减少,CWSI值增加,且CWSI同土壤含水量呈极显著负相关关系(p<0.01)。【结论】马铃薯的最大叶气温差与太阳辐射的线性关系作为马铃薯水分胁迫指数的上基线是可行的,该研究对传统CWSI经验模型进行改进,进一步优化了CWSI经验模型。展开更多
文摘The basic equations for computing the volume of gas storage tank were derived from the principles of attenuating water hammer pressure. Verifications using experiments indicate that the proposed equation can provide a fare precision in the predictions. By using the model of solid liquid two phase flow, the gas storage tank, pressure relief valves and slow closure reverse control valves were compared with practical engineering problems, and the functions of gas storage tank in attenuating water hammer pressure were further investigated. [
基金This research was supported by the Knowledge Innovation Project of Chinese Academy of Sciences (KZCX1-SW-01-15) and (KZCX1- SW-12)
文摘To obtain carbon dioxide (CO2) flux between water-air interface of Taihu lake, monthly water samplers at 14 sites and the local meteorological data of the lake were collected and analyzed in 1998. Carbon dioxide partial pressures (pCO2) at air-water interface in the lake were calculated using alkalinity, pH, ionic strength, active coefficient, and water temperature. The carbon fluxes at different sublakes and areas were estimated by concentration gradient between water and air in consideration of Schmidt numbers of 600 and daily mean windspeed at 10 m above water surface. The results indicated that the mean values of pCO2 in Wuli Lake, Meiliang Bay, hydrophyte area, west littoral zone, riverine mouths, and the open lake areas were 1 807.8±1 071.4 (mean±standard deviation) μatm (1atm=1.013 25×105Pa), 416.3±217.0 μatm, 576.5±758.8 μatm, 304.2±243.5 μatm, 1 933.6±1 144.7 μatm, and 448.5±202.6 μatm, respectively. Maximum and minimum pCO2 values were found in the hypertrophic (4 053.7 μatm) and the eutrophic (3.2 μatm) areas. The riverine mouth areas have the maximum fluxes (82.0±62.8 mmol/m2a). But there was no significant difference between eutrophic and mesot- rophic areas in pCO2 and the flux of CO2. The hydrophyte area, however, has the minimum (-0.58±12.9 mmol/m2a). In respect to CO2 equilibrium, input of the rivers will obviously influence inorganic carbon distribu- tion in the riverine estuary. For example, the annual mean CO2 flux in Zhihugang River estuary was 19 times of that in Meiliang Bay, although the former is only a part of the latter. The sites in the body of the lake show a clear seasonal cycle with pCO2 higher than atmospheric equilibrium in winter, and much lower than atmospheric in summer due to CO2 consumption by photosynthesis. The CO2 amount of the net annual evasion that enters the atmosphere is 28.42×104 t/a, of which those from the west littoral zone and the open lake account for 53.8% and 36.7%, respectively.
文摘As the performance of an air-cooled condenser is apt to be affected by the fluctuating ambient condition, some difficulties are brought to the use of a steam feeding water pump in an air-cooled unit. This paper introduces a new design of for steam feeding the water pump of an air-cooled unit using the back-pressure steam turbine as the prime motor. Using variable condition analysis on a 600 MW direct air-cooled unit, and with consideration of the effect on the ambient conditions, the feasibility, economy, and adaptability of the design are verified.
基金supported by the National Natural Science Foundation of China(Grant Nos. 50909089 and 40911140281)Qingdao S&T Development Program(09-1-3-41-jch)Korean Ministry of Land,Transport & Maritime Affairs through KORDI Program
文摘Oscillating Water Column (OWC) wave energy converting system is one of the most widely used facilities all over the world. The air chamber is utilized to convert the wave energy into the pneumatic energy. The numerical wave tank based on the two-phase VOF model is established in the present study toinvestigate the operating performance of OWC air chamber. The RANS equations, standard k-ε turbulence model and dynamic mesh technology are employed in the numerical model. The effects of incident wave conditions and shape parameters on the wave energy converting efficiency are studied and the capability of the present numerical wave tank on the corresponding engineering application is validated.
文摘The stable operation of the central air conditioning water system always is a major difficulty for the control profession. Paper focus on the water system with multi variable, strong coupling, nonlinear, large time delay characteristics, presented use feed forward coupling compensation method, to eliminate the coupling effect between temperature and pressure. In this paper, the Elman neural network controller is designed for the first time, and the simulation results show that the response time of Elman neural network controller is shorter, the system is more stable and the overshoot is small.
基金Project(Y5080022) supported by the Natural Science Foundation of Zhejiang Province,ChinaProject(RC1202) supported by Scientific and Technological Program of Water Resources Department of Zhejiang Province in 2012,ChinaProject(Y201224384) supported by Scientific Research Program of Education Department of Zhejiang Province in 2012,China
文摘In order to simulate the airflow in anhydrous case and the water-air flow in groundwater case, a numerical model of airflow in soil was developed. For the nonlinearity of the governing partial differential equation, the corresponding discretization and linearization methods were given. Due to the mass transfer between air-phase and water-phase, phase states of the model elements were constantly changing. Thus, parameters of the model were divided into primary ones and secondary ones, and the primary variables changing with phase states and the secondary variables can be obtained by their functional relationship with the primary variables. Additionally, the special definite condition of this numerical model was illustrated. Two examples were given to simulate the airflow in soil whether there was groundwater or not, and the effectiveness of the numerical model is verified by comparing the results of simulation with that of experiment.
文摘Sagarmatha (Mt. Everest) National Park (SNP) of Nepal is a popular international eco-touristic destination. In the last few years, tourist flow has increased tremendously generating anthropogenic pressure on natural environment. Generation of huge solid waste, open defecation and poor septic tank condition of toilets have been considered as the major sources of pollution to water bodies in the area. Heavy metals, such as cadmium, copper, lead, chromium and mercury, are important environmental pollutants, particularly in areas with high anthropogenic pressure. Their presence in the atmosphere, soil and water, even in traces can cause serious problems to all organisms, and heavy metal bioaccumulation in the food chain especially can be highly dangerous to human health. Heavy metals (Cu, Pb, Mn, Fe and Zn) and metals (Na, Mg) were analyzed. Thirty nine (13 samples in each year) water samples were collected from river and springs to assess the water quality in the SNP and its buffer zone. Water quality in the SNP has been found degraded in terms of heavy metals;particularly Na and Mg contents were found higher when compared with the earlier report. Iron content in 46% samples was found more than WHO and Nepalese standard for drinking water. The river water quality in general still stands good in terms of standard for drinking water (WHO, Nepal standard) however degradation process has accelerated.
文摘结合长距离无压引水隧洞充水过程,建立了水气两相流耦合VOF(Volume of Fluid)法的k-ε紊流模型,近壁面采用考虑糙率影响的壁面函数,结合实际工程对长距离无压引水隧洞水气两相流进行了模拟。模拟结果表明:隧洞内水位随充水时间的增加逐渐上升并趋于稳定;对隧洞充水过程中沿程典型断面的水气两相流进行了动态分析,结果表明进口流量为65 m3/s时水流能顺利通过隧洞;对某水库放水兼放空洞水深实测数据进行了验证对比,模拟结果与实验结果基本吻合。
文摘【目的】探究马铃薯的叶气温差与环境因子的关系,进一步优化马铃薯水分胁迫指数模型。【方法】在河南农业大学林学院试验基地进行马铃薯盆栽试验,选择晴朗天气测定不同土壤含水率下马铃薯的叶气温差随太阳辐射和大气饱和水汽压差(VPD)的变化规律,确定作物水分胁迫指数(crop water stress index,CWSI)的上下基线,进一步试验后得到优化后的马铃薯CWSI经验模型,并对相关模型进行验证。【结果】马铃薯的叶气温差随着土壤含水率的降低而升高;当土壤含水率较低(7.28%)时,马铃薯的叶气温差随太阳辐射的增大而增大,呈显著线性关系;当土壤含水率较高(15.85%)时,马铃薯的叶气温差随VPD的增大而减小,呈显著线性关系;构建出马铃薯CWSI的上基线为y=0.0098Q-0.68[Q为太阳辐射强度/(W·m^(-2))],下基线为y=-1.67V+3.75(V为大气饱和水汽压差/kPa);将优化的CWSI模型验证后得知,随着土壤含水率的减少,CWSI值增加,且CWSI同土壤含水量呈极显著负相关关系(p<0.01)。【结论】马铃薯的最大叶气温差与太阳辐射的线性关系作为马铃薯水分胁迫指数的上基线是可行的,该研究对传统CWSI经验模型进行改进,进一步优化了CWSI经验模型。