In this paper,adiabatic density surface,neutral density surface and potential density surface are compared.The adiabatic density surface is defined as the surface on which a water parcel can move adiabatically,without...In this paper,adiabatic density surface,neutral density surface and potential density surface are compared.The adiabatic density surface is defined as the surface on which a water parcel can move adiabatically,without changing its potential temperature and salinity.For a water parcel taken at a given station and pressure level,the corresponding adiabatic density surface can be determined through simple calculations.This family of surface is neutrally buoyant in the world ocean,and different from other surfaces that are not truly neutrally buoyant.In order to explore mixing path in the ocean,a mixing ratio m is introduced,which is defined as the portion of potential temperature and salinity of a water parcel that has exchanged with the environment during a segment of migration in the ocean.Two extreme situations of mixing path in the ocean are m=0(no mixing),which is represented by the adiabatic density curve,and m=1,where the original information is completely lost through mixing.The latter is represented by the neutral density curve.The reality lies in between,namely,0<m<1.In the turbulent ocean,there are potentially infinite mixing paths,some of which may be identified by using different tracers(or their combinations)and different mixing criteria.Searching for mixing paths in the real ocean presents a great challenge for further research.展开更多
Analytical and numerical simulation techniques have been developed for the calculation of earth resistance/ impedance and to estimate the potential distribution in the vicinity of earth electrodes.However,very little ...Analytical and numerical simulation techniques have been developed for the calculation of earth resistance/ impedance and to estimate the potential distribution in the vicinity of earth electrodes.However,very little literature is available on experimental validation of these calculation techniques.To address this,a programme of experimental tests on various earth electrodes has been carried out at the lower water reservoir of a hydro pumped-storage power station in North Wales.In this paper,the earthing test facility at Dinorwig power station is described including the details of the experimental set up.The results from experimental tests on a 5 mX5 m earth grid,immersed in water and energized under ac,dc and impulse,are presented.The values of measured earth resistance/impedance and water surface potential distributions are compared with those obtained from analytical calculations and detailed numerical computer simulations.展开更多
文摘In this paper,adiabatic density surface,neutral density surface and potential density surface are compared.The adiabatic density surface is defined as the surface on which a water parcel can move adiabatically,without changing its potential temperature and salinity.For a water parcel taken at a given station and pressure level,the corresponding adiabatic density surface can be determined through simple calculations.This family of surface is neutrally buoyant in the world ocean,and different from other surfaces that are not truly neutrally buoyant.In order to explore mixing path in the ocean,a mixing ratio m is introduced,which is defined as the portion of potential temperature and salinity of a water parcel that has exchanged with the environment during a segment of migration in the ocean.Two extreme situations of mixing path in the ocean are m=0(no mixing),which is represented by the adiabatic density curve,and m=1,where the original information is completely lost through mixing.The latter is represented by the neutral density curve.The reality lies in between,namely,0<m<1.In the turbulent ocean,there are potentially infinite mixing paths,some of which may be identified by using different tracers(or their combinations)and different mixing criteria.Searching for mixing paths in the real ocean presents a great challenge for further research.
文摘Analytical and numerical simulation techniques have been developed for the calculation of earth resistance/ impedance and to estimate the potential distribution in the vicinity of earth electrodes.However,very little literature is available on experimental validation of these calculation techniques.To address this,a programme of experimental tests on various earth electrodes has been carried out at the lower water reservoir of a hydro pumped-storage power station in North Wales.In this paper,the earthing test facility at Dinorwig power station is described including the details of the experimental set up.The results from experimental tests on a 5 mX5 m earth grid,immersed in water and energized under ac,dc and impulse,are presented.The values of measured earth resistance/impedance and water surface potential distributions are compared with those obtained from analytical calculations and detailed numerical computer simulations.
