1998 Vol. 20, No. 4
Display Method:
1998, 20(4): 1-8.
Abstract:
To the equations for oceanic internal waves under considering the horizontal component of the rotation vector,an asymptotic solution of the wave functions satisfying these equations is found.The oscillation characteristics of the asymptotic wave functions are studied.The results of research show that the effect of the horizontal component of the rotation vector on the high mode (the high wavenumber) internal waves in the ocean cannot be neglected.
To the equations for oceanic internal waves under considering the horizontal component of the rotation vector,an asymptotic solution of the wave functions satisfying these equations is found.The oscillation characteristics of the asymptotic wave functions are studied.The results of research show that the effect of the horizontal component of the rotation vector on the high mode (the high wavenumber) internal waves in the ocean cannot be neglected.
1998, 20(4): 9-16.
Abstract:
By using method of maxinum entropy spectrum,this paper analyses monthly mean sea level (MMSL) of 15 stations along the coast of China during the period of 1971-1995 and finds out that the main oscilations in these stations are one year and half year oscilalions,and the main low frequency period is 18.6 a in northern China.but 9 a or so in southern China.Then,the range of MMSL raising rate of (1.07±0.83) mm/a along the coast of China is liven by the method of stochastic dynamical prediction,in the mean time it is pointed out that the estimation of raising rate by using this method is affected by the length of MM-SL sequences and the low frequency periods.Finally,the contour plot of MMSL anomality along the coast of China during the study period is given,and it can be seen that the El Niño event mainly affects MMSL of southern China.
By using method of maxinum entropy spectrum,this paper analyses monthly mean sea level (MMSL) of 15 stations along the coast of China during the period of 1971-1995 and finds out that the main oscilations in these stations are one year and half year oscilalions,and the main low frequency period is 18.6 a in northern China.but 9 a or so in southern China.Then,the range of MMSL raising rate of (1.07±0.83) mm/a along the coast of China is liven by the method of stochastic dynamical prediction,in the mean time it is pointed out that the estimation of raising rate by using this method is affected by the length of MM-SL sequences and the low frequency periods.Finally,the contour plot of MMSL anomality along the coast of China during the study period is given,and it can be seen that the El Niño event mainly affects MMSL of southern China.
1998, 20(4): 17-24.
Abstract:
The key problem in the computation of fluid dynamics using fine boundary-fitted grids is how to improve the numerical stability and decrease the calculating quantity.To solve this problem,implicit schemes should be adopted since explicit schemes may bring about a great increase in computation quantity according to the Courant-Friedrichs-Lewy condition.Whereas the adoption of implicit schemes is difficult to be realized because of the existence of two partial derivatives of surface elevations with respect to variables of alternative direction coordinates in each momentum equation in non-rectangular coordinates.With an aim to design an implicit scheme in non-rectangular coordinate,new momentum equations with the contravariant components of velocity vector are derived based on the shallow water dynamic equations in generalized curvilinear coordinates.In each equation the coefficients before the two derivatives of surface elevations have different orders ofmagnitude,i.e.,the derivative with the larger coefficient may play a more important role than that with the smaller one.With this advantage,the ADI scheme can then be easily employed to improve the numerical stability and decrease the calculating quantity.The calculation in a harbour and a channel in Macao nearshore area shows that the implicit model is effective in calculating current fields in small size areas.
The key problem in the computation of fluid dynamics using fine boundary-fitted grids is how to improve the numerical stability and decrease the calculating quantity.To solve this problem,implicit schemes should be adopted since explicit schemes may bring about a great increase in computation quantity according to the Courant-Friedrichs-Lewy condition.Whereas the adoption of implicit schemes is difficult to be realized because of the existence of two partial derivatives of surface elevations with respect to variables of alternative direction coordinates in each momentum equation in non-rectangular coordinates.With an aim to design an implicit scheme in non-rectangular coordinate,new momentum equations with the contravariant components of velocity vector are derived based on the shallow water dynamic equations in generalized curvilinear coordinates.In each equation the coefficients before the two derivatives of surface elevations have different orders ofmagnitude,i.e.,the derivative with the larger coefficient may play a more important role than that with the smaller one.With this advantage,the ADI scheme can then be easily employed to improve the numerical stability and decrease the calculating quantity.The calculation in a harbour and a channel in Macao nearshore area shows that the implicit model is effective in calculating current fields in small size areas.
1998, 20(4): 25-37.
Abstract:
A nonlinear reduced-gravity oceanic model was applied to simulate the annual cycle in sea surface temperature in the South China Sea.Dynamic and thermodynamic mechanisms for formation and maintenance on the annual cycle were documented in series of numerical experiments forced by observational wind stresses and surface heat fluxes.The influences caused by changes in the external forcing functions and in the parameterization of entrainment occurring at the bottom of the upper mixed layer were investigated in this paper.Results showed that the variation stage and the spatial structure similar to observed climatology in the South China Sea had been achieved.It was found that the annual cycle was attributed to both wind stirring and surface heating.Moreover,the thermal balance in the upper layer in the South China Sea was strong seasonal time-dependent.
A nonlinear reduced-gravity oceanic model was applied to simulate the annual cycle in sea surface temperature in the South China Sea.Dynamic and thermodynamic mechanisms for formation and maintenance on the annual cycle were documented in series of numerical experiments forced by observational wind stresses and surface heat fluxes.The influences caused by changes in the external forcing functions and in the parameterization of entrainment occurring at the bottom of the upper mixed layer were investigated in this paper.Results showed that the variation stage and the spatial structure similar to observed climatology in the South China Sea had been achieved.It was found that the annual cycle was attributed to both wind stirring and surface heating.Moreover,the thermal balance in the upper layer in the South China Sea was strong seasonal time-dependent.
1998, 20(4): 38-46.
Abstract:
A baroclinic typhoon model with a moving multi-nested grid is.applied in marine environmental forecasts.The σ-coordinate primitive eyuations are used as governing eyuations in the model.The model with four uneven layers in the vertical and Arakawa-B grid in the horizontal is used in the National Marine Env,rnnmental Forecasting Centre of China.Finite differencing scheme for the model satisfies the conservation of momentum anti energy.The governing equations of the model are split into two parts which represent advection process and adjustment process,respectively.And different integration schemes with different time steps are employed for the two parts,respectively,according to the features of different processes in atmospheric motion.The forecasting and hindcasting show this numerical method can save computation time while having stable prediction results.
A baroclinic typhoon model with a moving multi-nested grid is.applied in marine environmental forecasts.The σ-coordinate primitive eyuations are used as governing eyuations in the model.The model with four uneven layers in the vertical and Arakawa-B grid in the horizontal is used in the National Marine Env,rnnmental Forecasting Centre of China.Finite differencing scheme for the model satisfies the conservation of momentum anti energy.The governing equations of the model are split into two parts which represent advection process and adjustment process,respectively.And different integration schemes with different time steps are employed for the two parts,respectively,according to the features of different processes in atmospheric motion.The forecasting and hindcasting show this numerical method can save computation time while having stable prediction results.
1998, 20(4): 47-51.
Abstract:
By making use of the distinguishing features of repetitive imagery of the same area by satellite remotesensing.a method of extracting water areas at different tidal levels from the images of bays at different times was adopted to establish a calculating model for tidal surface and a method of finding a sum by layers was used to establish a calculating model for the deposition parameter.Moreover,by making use of the calculating models for the deposition parameter and for tidal level,the deposition parameter for the sea area less than 0 m was calculated for the Haikou Bay at two different periods of time:during the period of 1965-1984 the total amount of deposits was 4.8 ×106m3,and the sedimentation rate was 2.5×l05m3/a;during the period from 1984 to 1990,the total amount of deposits was -8.9×105m3 and the sedimentation rate was -1.5×105m3/a.
By making use of the distinguishing features of repetitive imagery of the same area by satellite remotesensing.a method of extracting water areas at different tidal levels from the images of bays at different times was adopted to establish a calculating model for tidal surface and a method of finding a sum by layers was used to establish a calculating model for the deposition parameter.Moreover,by making use of the calculating models for the deposition parameter and for tidal level,the deposition parameter for the sea area less than 0 m was calculated for the Haikou Bay at two different periods of time:during the period of 1965-1984 the total amount of deposits was 4.8 ×106m3,and the sedimentation rate was 2.5×l05m3/a;during the period from 1984 to 1990,the total amount of deposits was -8.9×105m3 and the sedimentation rate was -1.5×105m3/a.
1998, 20(4): 52-59.
Abstract:
Biogeochemical process of major elements has been systematically studied in sinking particulate of Nansha coral reef lagoons,the South China Sea.The main results are as follows:The contents and vertical fluxes of major elements in Nansha coral reef lagoons were different.Vertical fluxes of most major elements in Yongshu Reef lagoon were higher than those in Zhubi Reef lagoon.Ca has the highest flux,about 1.4 g/cm2·d).Na,K,Ca,Mg and Sr were transferred onto sea floor mainly in carbonate in Yongshu Reef lagoon,Fe,I and Ba in iron-manganese oxides and Al,Br in silicate,Cl transformation tended to be in the forms of carbonate and silicate.Pdost of Br,K,A1,I in sinking particulate can recycle into seawater,half of total Mg,Na and Cl can be released into seawater.Most of Ca,Sr,Ba and Fe can be really precipitated into sediment.The order of precipitation ratio was Ca >Mg >I >Al >Br >K.Vertical fluxes of major elemenu have close relationship with SST.Na and other 8 elements decreased exponentially with SST,but K and Ba had not the relationship.The order of sensitivities to SST was Fe >Br >Sr >Ca >Na >Cl >Mg >I >Al.The vertical flux changes of Fe and Br can react SST variation.
Biogeochemical process of major elements has been systematically studied in sinking particulate of Nansha coral reef lagoons,the South China Sea.The main results are as follows:The contents and vertical fluxes of major elements in Nansha coral reef lagoons were different.Vertical fluxes of most major elements in Yongshu Reef lagoon were higher than those in Zhubi Reef lagoon.Ca has the highest flux,about 1.4 g/cm2·d).Na,K,Ca,Mg and Sr were transferred onto sea floor mainly in carbonate in Yongshu Reef lagoon,Fe,I and Ba in iron-manganese oxides and Al,Br in silicate,Cl transformation tended to be in the forms of carbonate and silicate.Pdost of Br,K,A1,I in sinking particulate can recycle into seawater,half of total Mg,Na and Cl can be released into seawater.Most of Ca,Sr,Ba and Fe can be really precipitated into sediment.The order of precipitation ratio was Ca >Mg >I >Al >Br >K.Vertical fluxes of major elemenu have close relationship with SST.Na and other 8 elements decreased exponentially with SST,but K and Ba had not the relationship.The order of sensitivities to SST was Fe >Br >Sr >Ca >Na >Cl >Mg >I >Al.The vertical flux changes of Fe and Br can react SST variation.
1998, 20(4): 60-64.
Abstract:
The effect of petroleum pollution on the Tilapia mossambhca was studied by analysing the changes of activities of serum glutamic-oxalacetic transaminase(GOT),alkaline phosphatase(ALP)and lactate dehydrogenase (LDH).The study results show that:(1)The activities of serum GUT,ALP and LDH increase in petroleum treated Tilapia mossambica.(2) The threshold of effect of petroleum on serum enzymes is 0.05 mg/dm3.We think that it can diagnose the petroleum pollution by analysing the variances of activities of thoseenzymes.
The effect of petroleum pollution on the Tilapia mossambhca was studied by analysing the changes of activities of serum glutamic-oxalacetic transaminase(GOT),alkaline phosphatase(ALP)and lactate dehydrogenase (LDH).The study results show that:(1)The activities of serum GUT,ALP and LDH increase in petroleum treated Tilapia mossambica.(2) The threshold of effect of petroleum on serum enzymes is 0.05 mg/dm3.We think that it can diagnose the petroleum pollution by analysing the variances of activities of thoseenzymes.
1998, 20(4): 65-71.
Abstract:
Anew pattern recognition technique of fluorescence spectra based on vector distance in n-dimensional space was established for the source identification of oil spills on sea.Four wavelengths of both excitation and emission were used as digitizing points of fluorescence spectrum.Three unweathered crude oils,four heavy fuels and two lubricating oils were analyized,and their digitized fluorescence spectra were studied.The reliability of this pattern recognition technique was tested by analyzing 11 bunker oils collected from different ships,and the smallest vector distance under the experimental conditions was Aiven.
Anew pattern recognition technique of fluorescence spectra based on vector distance in n-dimensional space was established for the source identification of oil spills on sea.Four wavelengths of both excitation and emission were used as digitizing points of fluorescence spectrum.Three unweathered crude oils,four heavy fuels and two lubricating oils were analyized,and their digitized fluorescence spectra were studied.The reliability of this pattern recognition technique was tested by analyzing 11 bunker oils collected from different ships,and the smallest vector distance under the experimental conditions was Aiven.
1998, 20(4): 72-82.
Abstract:
By using optic and acoustic sensors,the fluid mud layer was detected in turbidity maximum of the Jiaojiang Estuary during thre:cruises carried out in 1991,1994 and 1995.Records of time series of stations and transects across and along the river channel were collected.The data reveal that,in addition to the cyclic migration corresponded to the river runoff and tide prism.the fluid mud layer tends to concentrate on depressions or on one side of channel opposite its current-dominated channel.Such two tendencies result in a large suspended sediment reservoir being very sensitive to the boundary conditions of the turbidity maximum.
By using optic and acoustic sensors,the fluid mud layer was detected in turbidity maximum of the Jiaojiang Estuary during thre:cruises carried out in 1991,1994 and 1995.Records of time series of stations and transects across and along the river channel were collected.The data reveal that,in addition to the cyclic migration corresponded to the river runoff and tide prism.the fluid mud layer tends to concentrate on depressions or on one side of channel opposite its current-dominated channel.Such two tendencies result in a large suspended sediment reservoir being very sensitive to the boundary conditions of the turbidity maximum.
1998, 20(4): 83-90.
Abstract:
The diatom and foraminifera analysis is made for the samples of Late Wurm sedimentary layers determined by palynology,radiocarbon dating and paleomagnetism from 14 cores in the estuarine plains and sea area of the western Taiwan Strait.The results show that the sedimentary layers at that time in the sea area are all marine sediments and those in the estuarine plain are composed of alternate marine and terrigeneous strata.Accordingly,an idea is proposed by authors that the Taiwan Strait in Late Wurm glaciation belongs to the shallow sea sedimentary environment with a water depth of 30-50 m.Thus a phenomenon inconsistent with the eustatic sea-level rise and fall caused by global climatic cold-warm replacement is suggested to be due to the differential crustal movement.During Late Wurm glaciation,the Taiwan Strait is subjected to the crustal intermittent falling so as to keep a shallow sea environment.
The diatom and foraminifera analysis is made for the samples of Late Wurm sedimentary layers determined by palynology,radiocarbon dating and paleomagnetism from 14 cores in the estuarine plains and sea area of the western Taiwan Strait.The results show that the sedimentary layers at that time in the sea area are all marine sediments and those in the estuarine plain are composed of alternate marine and terrigeneous strata.Accordingly,an idea is proposed by authors that the Taiwan Strait in Late Wurm glaciation belongs to the shallow sea sedimentary environment with a water depth of 30-50 m.Thus a phenomenon inconsistent with the eustatic sea-level rise and fall caused by global climatic cold-warm replacement is suggested to be due to the differential crustal movement.During Late Wurm glaciation,the Taiwan Strait is subjected to the crustal intermittent falling so as to keep a shallow sea environment.
1998, 20(4): 91-96.
Abstract:
Effects of temperature on oxygen consumption rate and ammonia-N excretion rate of the Southern Bay scallop Argopecten irradians ceucoutricus (1.6-4.8 cm in shell height,0.039 2-0.690 8 g in dry weight of soft tissue) were studied in laboratory from Dec.30,1996 to Jan.28,1997.Under the controlled conditions of ambient temperature 10-31℃ and salinity 32,the concentration of dissolved oxygen and ammonia-N were determined by the Winkler method and the hypobromite method respectively.Results show that the range of oxygen consumption rate was from 1.06 to 5.18 mg/ (g·h),mean of 2.35 mg/(g·h).The relationship between oxygen consumption quantity(mg/h)and dry weight of soft-tissue (g) can be represented by the allometric equation O=aWb,b value was 0.748 2-0.937 3.The oxygen consumption rate increased with temperature increasing at 10-28℃,but reduced at 31℃.Effect of temperature on oxygen consumption rate (10-28℃) can be described by Os=r1er2t,r,the correlation coefficient was 0.194 0-0.944 0.The range of ammonia-N excretion rate was from 111.28 to 791.91 μg/(g·h),mean of 350.89 μg/(g·h).The relationship between ammonia-N excretion quantity (p.g/h) and dry weight of soft tissue can also be represented as the allometric equation:N=cWd,and d value was 0.765 4-0.852 8.The ammonia-N excretion rate increased at the temperature from 10℃ to 31℃,and the impact of temperature on ammonia-N excretion rate can be represented by Na=q1eq2t.r was 0.877 2-0.967 2.It is indicated that high temperature (31℃)can improve the level of protein metabolism in this experiment.The linear regression relationships among oxygen consumption quantity and temperature and dry weight of soft tissue can be described by O=-252.780+25.624t+1 509.917W,and ammonia-N excretion quantity by N=-38.758+2.794t+175.228W.the multiple r were 0.880 6 and 0.803 5,respectively.
Effects of temperature on oxygen consumption rate and ammonia-N excretion rate of the Southern Bay scallop Argopecten irradians ceucoutricus (1.6-4.8 cm in shell height,0.039 2-0.690 8 g in dry weight of soft tissue) were studied in laboratory from Dec.30,1996 to Jan.28,1997.Under the controlled conditions of ambient temperature 10-31℃ and salinity 32,the concentration of dissolved oxygen and ammonia-N were determined by the Winkler method and the hypobromite method respectively.Results show that the range of oxygen consumption rate was from 1.06 to 5.18 mg/ (g·h),mean of 2.35 mg/(g·h).The relationship between oxygen consumption quantity(mg/h)and dry weight of soft-tissue (g) can be represented by the allometric equation O=aWb,b value was 0.748 2-0.937 3.The oxygen consumption rate increased with temperature increasing at 10-28℃,but reduced at 31℃.Effect of temperature on oxygen consumption rate (10-28℃) can be described by Os=r1er2t,r,the correlation coefficient was 0.194 0-0.944 0.The range of ammonia-N excretion rate was from 111.28 to 791.91 μg/(g·h),mean of 350.89 μg/(g·h).The relationship between ammonia-N excretion quantity (p.g/h) and dry weight of soft tissue can also be represented as the allometric equation:N=cWd,and d value was 0.765 4-0.852 8.The ammonia-N excretion rate increased at the temperature from 10℃ to 31℃,and the impact of temperature on ammonia-N excretion rate can be represented by Na=q1eq2t.r was 0.877 2-0.967 2.It is indicated that high temperature (31℃)can improve the level of protein metabolism in this experiment.The linear regression relationships among oxygen consumption quantity and temperature and dry weight of soft tissue can be described by O=-252.780+25.624t+1 509.917W,and ammonia-N excretion quantity by N=-38.758+2.794t+175.228W.the multiple r were 0.880 6 and 0.803 5,respectively.
1998, 20(4): 97-102.
Abstract:
A study on the relation between the evolution and structure of secondary xylem of the mangrove Bruguiera sexangula,B.uguiera gymnerrhixa,Ceriops tagal and Kandelia candel (Rhizophoraceae).Avicennia marina (Verbenaceae),Aegiceras eorniculatum (Mysinaceae) and Sonneratia caeseolaria (Sonneratiaceae) is made.The results are shown as follows:Secondary xylem of mangrove species in Rhizophoraceae is more primitive than those of mangrove species in Verbenaceae,Mysinaceae and Sonneratiaceae,Carallia and Pellacalyx belong to Rhizophoraceae of terrestrial plants but are not mangrove species and they have more evolutionary secondary xylem,namely,simple perforation vessel and alternate pit-pair,than mangrove species such as Bruguiera,Ceriops and Kandelia (Rhizophoraceae).The form of simple perforation vessel is a specialization phenomenon in dry environment during the long evolution.But the secondary xylem characteristics of mangrove species in Rhizophoraceae remained primitive,after they entered the seashore wetlands.
A study on the relation between the evolution and structure of secondary xylem of the mangrove Bruguiera sexangula,B.uguiera gymnerrhixa,Ceriops tagal and Kandelia candel (Rhizophoraceae).Avicennia marina (Verbenaceae),Aegiceras eorniculatum (Mysinaceae) and Sonneratia caeseolaria (Sonneratiaceae) is made.The results are shown as follows:Secondary xylem of mangrove species in Rhizophoraceae is more primitive than those of mangrove species in Verbenaceae,Mysinaceae and Sonneratiaceae,Carallia and Pellacalyx belong to Rhizophoraceae of terrestrial plants but are not mangrove species and they have more evolutionary secondary xylem,namely,simple perforation vessel and alternate pit-pair,than mangrove species such as Bruguiera,Ceriops and Kandelia (Rhizophoraceae).The form of simple perforation vessel is a specialization phenomenon in dry environment during the long evolution.But the secondary xylem characteristics of mangrove species in Rhizophoraceae remained primitive,after they entered the seashore wetlands.
1998, 20(4): 103-106.
Abstract:
Forty old Pagrosomus major juvenile had been feeded with Brachionus plicatilis、Limmodrillus、Harpodon nehereus gruel and plant mixed diet respectively for 2 d.Then,the specific activity of protease was the highest in juvenile feeded with Brachionus plicatilis,the second with Harpodon nehereus,the non-activity with Limmodrillus and mixed diet.The specific activity of α-amylase was the highest with mixd diet,the second with Brachionus plicatilis and Harpodon nehereus,the lowest with Limmodrillus.The specific activity of lipase was the highest with mixed diet,the second with Brachionus plicatilis and Limmodrillus,the lowest with harpodon nehereus.It was suggested that Limmodrillus and plant protein were not fit to Pagrosomus major juvenile,the activity of α-amylase was reduced distinctly by food,the activity of lipase was negative related with fat amount contained in food.
Forty old Pagrosomus major juvenile had been feeded with Brachionus plicatilis、Limmodrillus、Harpodon nehereus gruel and plant mixed diet respectively for 2 d.Then,the specific activity of protease was the highest in juvenile feeded with Brachionus plicatilis,the second with Harpodon nehereus,the non-activity with Limmodrillus and mixed diet.The specific activity of α-amylase was the highest with mixd diet,the second with Brachionus plicatilis and Harpodon nehereus,the lowest with Limmodrillus.The specific activity of lipase was the highest with mixed diet,the second with Brachionus plicatilis and Limmodrillus,the lowest with harpodon nehereus.It was suggested that Limmodrillus and plant protein were not fit to Pagrosomus major juvenile,the activity of α-amylase was reduced distinctly by food,the activity of lipase was negative related with fat amount contained in food.
1998, 20(4): 107-113.
Abstract:
A total of 191 Anguilla japonica elvers,collected at 6 locations along the Chinese coast were observed in order to determine age and to measure body length.The average length of elvers at 6 locations ranged from (53.4±2.2) to (58.1±1.7) mm(X±S.D).There were no relationship between body length and location of elvers distribution.The average daily ages of elvers at 6 locations ranged from (138.2±6.7) to (155.2±9.0) d(X±S.D).The maximum radius,check around the nucleus,average growth increment width and the changes of the increment width of otolith were compared.The average radius of otoliths of elvers at 6 locations ranged from (142.5±8.4) to (155.8±14.5) μm(X±S.D).The average maximum diameters of the check around the nucleus of the otoliths ranged from (10.36±0.85) to (10.81±1.26) μm (X±S.D),there was no significantly different among them (p>0.0l).The average increment width of otoliths ranged from 0.996 to 1.097 μm,there was significantly different among them (p<0.0l).The growth rate of the otolith was the highest at Wenchou and the Changjiang Estuary.The growth rate of the otoliths declined gradually at other locations towards both lower and higher latitude,respectively.The increment width of the otoliths was the highest at approximately 90-days old at 6 locations.The average daily ages of elvers at the Changjiang Estuary and Wenchou were the youngest.The daily ages of elvers declined gradually at other locations towards both lower and higher latitude respectively while the position of Wenchou and the Changjiang Estuary was the center at 6 locations.Estimated birth date based on the daily ages at 6 locations ranged from 15 August,1993 to 10 Janaury,1994.The individual at lower latitude is earlier birth but no younger,and recruit earlier.
A total of 191 Anguilla japonica elvers,collected at 6 locations along the Chinese coast were observed in order to determine age and to measure body length.The average length of elvers at 6 locations ranged from (53.4±2.2) to (58.1±1.7) mm(X±S.D).There were no relationship between body length and location of elvers distribution.The average daily ages of elvers at 6 locations ranged from (138.2±6.7) to (155.2±9.0) d(X±S.D).The maximum radius,check around the nucleus,average growth increment width and the changes of the increment width of otolith were compared.The average radius of otoliths of elvers at 6 locations ranged from (142.5±8.4) to (155.8±14.5) μm(X±S.D).The average maximum diameters of the check around the nucleus of the otoliths ranged from (10.36±0.85) to (10.81±1.26) μm (X±S.D),there was no significantly different among them (p>0.0l).The average increment width of otoliths ranged from 0.996 to 1.097 μm,there was significantly different among them (p<0.0l).The growth rate of the otolith was the highest at Wenchou and the Changjiang Estuary.The growth rate of the otoliths declined gradually at other locations towards both lower and higher latitude,respectively.The increment width of the otoliths was the highest at approximately 90-days old at 6 locations.The average daily ages of elvers at the Changjiang Estuary and Wenchou were the youngest.The daily ages of elvers declined gradually at other locations towards both lower and higher latitude respectively while the position of Wenchou and the Changjiang Estuary was the center at 6 locations.Estimated birth date based on the daily ages at 6 locations ranged from 15 August,1993 to 10 Janaury,1994.The individual at lower latitude is earlier birth but no younger,and recruit earlier.
1998, 20(4): 114-120.
Abstract:
Much attentions have been paid on the study of hydrodynamic interaction between multiple objects which is known as an important factor in the design and study of super-large offshore structures.A systematic study has been carried out on the interaction effects of three-dimensional wave forces on vertical pile arrays by using the wave source distribution method.Not only can the properties of hydrodynamic interaction of single row piles be got,but also some new discoveries are found for the pile arrays of multiple rows.It is found that the shield effect of multiple rows is larger than single one.There is a sensitive wave frequency range in which the variation of the wave forces will probably much larger than those in the other frequency range.The mechanical characteristics for the matrix-like pile arrays are different from those for the staggered pile arrays.Those discoveries may give important guidance to the design of the super-large offshore structures.
Much attentions have been paid on the study of hydrodynamic interaction between multiple objects which is known as an important factor in the design and study of super-large offshore structures.A systematic study has been carried out on the interaction effects of three-dimensional wave forces on vertical pile arrays by using the wave source distribution method.Not only can the properties of hydrodynamic interaction of single row piles be got,but also some new discoveries are found for the pile arrays of multiple rows.It is found that the shield effect of multiple rows is larger than single one.There is a sensitive wave frequency range in which the variation of the wave forces will probably much larger than those in the other frequency range.The mechanical characteristics for the matrix-like pile arrays are different from those for the staggered pile arrays.Those discoveries may give important guidance to the design of the super-large offshore structures.
1998, 20(4): 121-132.
Abstract:
The wave actions on a cylinder in 3-D random waves are experimentally studied.The 2-D wave method is extended to calculate the 3-D wave forces.The variations of various hydrodynamic coefficients with KC number and wave directional spreading are investigated.The 3-D wave forces are compared with that of the 2-D waves.
The wave actions on a cylinder in 3-D random waves are experimentally studied.The 2-D wave method is extended to calculate the 3-D wave forces.The variations of various hydrodynamic coefficients with KC number and wave directional spreading are investigated.The 3-D wave forces are compared with that of the 2-D waves.
1998, 20(4): 133-140.
Abstract:
There have been more than 10 factors to be used to characterize the intensity of wave groups since the spectral peakness parameter,QP,was proposed by Yoshimi Uoda in 1970.As to 11 factors more currently employed,i.e.,hereafter called existing grouping factors,mentioned in the paper,each of the authors puts emphasis on the advantage of his own.Which of the existing grouping factors is better? Nobody made an objective appraisement as yet.New a trial examination of the existing grouping factors has been made on the basis of 111 data sets obtained from three observation points in the paper.If one of the existing grouping factorn which has the maximum and minimum value among three values in succession within a shorter record satisfying that maximum value minus-minimun value is not greater than 0.005,then it is called the steady grouping factor.If this factor satisfies the other three conditions:the most frequency in an arbitrary ordinal number,the most total frequency in the whole record,and the largest occurrence probability within initial 1 280 s of the whole record,then it is called better grouping factor.So far as the cases are examined,to this factor belong the mean length of runs [of wave heights (L1)and correlation coefficient between wave heights and periods [RHT (0)];the two factors are connected which are hereafter called a united grouping factor.Therefore,we suggest that the united grouping factor characterized the intensity of wave groups shows better than single one adopted by forerunners.
There have been more than 10 factors to be used to characterize the intensity of wave groups since the spectral peakness parameter,QP,was proposed by Yoshimi Uoda in 1970.As to 11 factors more currently employed,i.e.,hereafter called existing grouping factors,mentioned in the paper,each of the authors puts emphasis on the advantage of his own.Which of the existing grouping factors is better? Nobody made an objective appraisement as yet.New a trial examination of the existing grouping factors has been made on the basis of 111 data sets obtained from three observation points in the paper.If one of the existing grouping factorn which has the maximum and minimum value among three values in succession within a shorter record satisfying that maximum value minus-minimun value is not greater than 0.005,then it is called the steady grouping factor.If this factor satisfies the other three conditions:the most frequency in an arbitrary ordinal number,the most total frequency in the whole record,and the largest occurrence probability within initial 1 280 s of the whole record,then it is called better grouping factor.So far as the cases are examined,to this factor belong the mean length of runs [of wave heights (L1)and correlation coefficient between wave heights and periods [RHT (0)];the two factors are connected which are hereafter called a united grouping factor.Therefore,we suggest that the united grouping factor characterized the intensity of wave groups shows better than single one adopted by forerunners.
1998, 20(4): 141-144.
Abstract:
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