The functioning mechanism of groundwater and its make-up water in the process of ground subsidence was studied from such three aspects as osmotic corrasion, osmotic pressure effect and concretion effect, As to osmotic...The functioning mechanism of groundwater and its make-up water in the process of ground subsidence was studied from such three aspects as osmotic corrasion, osmotic pressure effect and concretion effect, As to osmotic corrasion, its forming conditions, mechanical mechanism and process were analyzed, As to osmotic pressure effect, it was mainly studied from hydrostatic pressurizing effect, sop softening effect and negative pressure sealing effect. Through concretion and saturation of soil, the factors of concretion settlement were analyzed. The results showed that both groundwater and its make-up water are important triggering factors to ground subsidence.展开更多
To analyze the effect of the way of water entry on water impact, the FLUENT software was adopted to simulate a two-dimensional (2D) helicopter V-buoy’s free fall and forced fall at a constant velocity.Combining with ...To analyze the effect of the way of water entry on water impact, the FLUENT software was adopted to simulate a two-dimensional (2D) helicopter V-buoy’s free fall and forced fall at a constant velocity.Combining with the UDF program and the dynamic mesh model, the standard k-ε turbulence model was used and the VOF technique was adopted to capture free surface.The physical parameters such as velocity and force were calculated and compared with those results of boundary element method with good agreement obtained.It was found that the force of 2D V-buoy at a constant velocity was much greater than that in free fall motion.Meanwhile, the maximum pressure coefficients C p max in both cases were almost equal and the dimensionless water-entry depths y' corresponding to C p max were also similar.展开更多
The NB （Nile River Basin） is considered one of the most population lives in its riparian countries. Out of the latter about 50% live important basins in Africa, as over 33% of the African in the NB. In this paper a ...The NB （Nile River Basin） is considered one of the most population lives in its riparian countries. Out of the latter about 50% live important basins in Africa, as over 33% of the African in the NB. In this paper a historical background on the NB cooperation evolvement including the recent NBI （NB Initiative） is briefly reported. The natural and human challenges facing the Nile water management are examined and discussed. The present dilemma among the Nile riparian countries is highlighted and its reasons are explained. The latter includes the NB CFA （Cooperative Framework Agreement）, which has been signed by six countries （Burundi, Ethiopia, Kenya, Rwanda, Tanzania and Uganda） while rejected by Egypt, Sudan and not signed by DR of Congo. Eretria and the newly established country ＂South Sudan＂ stands are not yet clear. Based on scientific methodology and analytical discussion, a number of solutions for better management of the trans-boundary Nile waters are drawn; taking into consideration the experiences of other international rivers shared basins. Finally, the paper concludes with recommendations and guidelines that may help in the way forward.展开更多
The most restrictive factor in the way of economic prosperity in China’s northwest lies in the lack of water resources.To seek countermeasures against this ages-old scourge of the arid hinterland,the CAS Division of ...The most restrictive factor in the way of economic prosperity in China’s northwest lies in the lack of water resources.To seek countermeasures against this ages-old scourge of the arid hinterland,the CAS Division of Earth Sciences sponsored a workshop in Beijing on tapping water resources of Chinese northwest in March 1995 and decided to organize an expedition team of CAS members to investigate the water resources there.From August 23 to September 5,1995,the team carried out an on-the-spot survey along a 3,000-kilometre-long itiner-展开更多
基金financially supported by the National Nature Science Foundation of China (No.50490271)the National Key Technologies R & D Program of China (No.2004BA615A-18).
文摘The functioning mechanism of groundwater and its make-up water in the process of ground subsidence was studied from such three aspects as osmotic corrasion, osmotic pressure effect and concretion effect, As to osmotic corrasion, its forming conditions, mechanical mechanism and process were analyzed, As to osmotic pressure effect, it was mainly studied from hydrostatic pressurizing effect, sop softening effect and negative pressure sealing effect. Through concretion and saturation of soil, the factors of concretion settlement were analyzed. The results showed that both groundwater and its make-up water are important triggering factors to ground subsidence.
基金Sponsored by the National Natural Science Foundation of China(Grant Nos.51639004 and 51579054)
文摘To analyze the effect of the way of water entry on water impact, the FLUENT software was adopted to simulate a two-dimensional (2D) helicopter V-buoy’s free fall and forced fall at a constant velocity.Combining with the UDF program and the dynamic mesh model, the standard k-ε turbulence model was used and the VOF technique was adopted to capture free surface.The physical parameters such as velocity and force were calculated and compared with those results of boundary element method with good agreement obtained.It was found that the force of 2D V-buoy at a constant velocity was much greater than that in free fall motion.Meanwhile, the maximum pressure coefficients C p max in both cases were almost equal and the dimensionless water-entry depths y' corresponding to C p max were also similar.
文摘The NB （Nile River Basin） is considered one of the most population lives in its riparian countries. Out of the latter about 50% live important basins in Africa, as over 33% of the African in the NB. In this paper a historical background on the NB cooperation evolvement including the recent NBI （NB Initiative） is briefly reported. The natural and human challenges facing the Nile water management are examined and discussed. The present dilemma among the Nile riparian countries is highlighted and its reasons are explained. The latter includes the NB CFA （Cooperative Framework Agreement）, which has been signed by six countries （Burundi, Ethiopia, Kenya, Rwanda, Tanzania and Uganda） while rejected by Egypt, Sudan and not signed by DR of Congo. Eretria and the newly established country ＂South Sudan＂ stands are not yet clear. Based on scientific methodology and analytical discussion, a number of solutions for better management of the trans-boundary Nile waters are drawn; taking into consideration the experiences of other international rivers shared basins. Finally, the paper concludes with recommendations and guidelines that may help in the way forward.
文摘The most restrictive factor in the way of economic prosperity in China’s northwest lies in the lack of water resources.To seek countermeasures against this ages-old scourge of the arid hinterland,the CAS Division of Earth Sciences sponsored a workshop in Beijing on tapping water resources of Chinese northwest in March 1995 and decided to organize an expedition team of CAS members to investigate the water resources there.From August 23 to September 5,1995,the team carried out an on-the-spot survey along a 3,000-kilometre-long itiner-
