Some properties of surf-beats

Long ocean waves with periods of several minutes (surf-beats) were observed at a marine observation tower. We have analysed time series data of an envelope of incident swell, long period current velocity and surface elevation fluctuations. Current velocity was measued by an electromagnetic flow meter. Surf-beats amplitudeH ^(l) is shown to be proportional to 3/2 power of incident swell amplitudeH ^(s), and decreases with increase of depthh in proportional toh ^–1/2 such thatH ^(l) H ^(s) (H ^(s)/h)^1/2. Frequency energy density functionP _LL (f) of surface elevation had two dominant peaks whose frequencies were highly stable through the entire observational period. Cross-spectral analysis suggested that those peaks correspond to traveling edge waves caused by the excess momentum and mass flux in the surf zone. The forced long ocean waves predicted byLonguet-Higgins andStewart (1964) was ditected. Phase-shift and wave height of the wave with respect to those of incident swell envelope are shown to be in remarkable agreement with the predictions. However the forced long wave is only a minor component in the total energy of surf-beats. Current fields are shown to be largely composed of non-surface modes.     

Thermal bending of thin, anisotropic, clamped elliptic plates

The present note deals with the exact analytical solution of thermal bending of clamped, anisotropic, elliptic plates in the case where the thermal field is given by an expression of the type T(x,y,z)=z(Ax²+Cxy+By²).The problem is of basic interest in some ocean and mechanical structural systems since anisotropic materials are commonly used in those fields. Obviously the case of an orthotropic material constitutes a particular situation of the problem under study.     

Thermal bending of thin,anisotropic, clamped elliptic plates

The present note deals with the exact analytical solution of thermal bending of clamped, anisotropic, elliptic plates in the case where the thermal field is given by an expression of the type T(x,y,z)=z(Ax²+Cxy+By²).The problem is of basic interest in some ocean and mechanical structural systems since anisotropic materials are commonly used in those fields. Obviously the case of an orthotropic material constitutes a particular situation of the problem under study.     

海南省海岸带典型区域海水入侵现状评价

基于海南省东部和南部海岸带地区地下水现场监测数据和室内水化学测定数据,研究了各水化学指标间的相关性,分析了区域海水入侵现状。研究结果表明地下水中Cl~–与Na~+的变异系数较高,与矿化度(TDS)具有强的相关性;以m(Cl~–)(m表示质量浓度)和TDS分别作为评价因子开展了海水入侵现状评价,结果表明研究区域内地下水未受到海水入侵的影响;m(Na~+)/m(Cl~–)、 m(Cl~–)/m(HCO_3~–)、m(Cl~–)/m(SO_4~(2–))、m(Ca~(2+))/m(Na~+)、m(Ca~(2+))/m(Mg~(2+))、钠吸附比(SAR)与m(Cl~–)的相关性分析结果表明m(Na~+)/m(Cl~–)、m(Ca~(2+))/m(Na~+)、m(Ca~(2+))/m(Mg~(2+))以及SAR4个参数可以作为海南省海水入侵判定的评价因子。研究结果对建设海南省"国际旅游岛"战略目标,指导当地合理利用地下水具有参考价值。     

Equilibrium and structural studies of silicon(IV) and aluminium(III) in aqueous solution. II. Formation constants for the monosilicate ions SiO(OH)3 and SiO2(OH)2. A precision study at 25°C in a simplified seawater medium

The hydrolysis of silicic acid, Si(OH)₄, was studied in a simplified seawater medium (0.6 M Na(Cl)) at 25°C. The measurements were performed as potentiometric titrations (hydrogen electrode) in which OH⁻ was generated coulometrically. The total concentration of Si(OH)₄, B, and log[H⁺] were varied within the limits 0.00075 B 0.008 M and 2.5 -log[H⁺] 11.7, respectively. Within these ranges the formation of SiO(OH)₃⁻ and SiO₂(OH)₂²⁻ with formation constants log β₋₁₁(Si(OH)₄ SiO(OH)₃⁻ + H⁺) = −9.472 ±0.002 and log β₋₂₁(Si(OH)₄ SiO₂(OH)₂²⁻ + 2H⁺) = −22.07 ± 0.01 was established. With B > 0.003 M polysilicate complexes are formed, however, with -log[H⁺] 10.7 their formation does not significantly affect the evaluated formation constants. Data were analyzed with the least squares computer program LETAGROPVRID.     

Single electron loss in the collisions of C3 + and atomic hydrogen

This paper studies the projectile electron loss cross sections of C^{3 +} colliding with atomic hydrogen in the frame work of extended over-barrier model at intermediate velocities (25 keV/u--600 keV/u). The electron loss is calculated in terms of the interaction between the screened target nucleus and the active projectile electron and of the interaction between projectile electron and target electron. Compared with the convergent close-coupling calculations, screening and anti-screening calculations, this model satisfactorily reproduces the experimentally obtained energy dependence of the electron-impact ionisation cross sections and the single electron loss cross sections over the energy range investigated here.     

Ionisation of Rydberg hydrogen atom near a metal surface by short pulse laser

In the ionisation of Rydberg hydrogen atoms near a metal surface, the electron will escape from the nucleus and arrive at the detector in a time sequence. This probability flux train relies on the initial electron wave packet irradiated by the laser pulse. For simplicity, the laser pulse is usually simplified to a delta function in energy domain, resulting in a sharp initial arrival time with an exponentially decaying tail at the detector. Actually and semiclassically, the initial outgoing wave should be modeled as an ensemble of trajectories propagating away from the atomic core in all directions with a range of launch times and a range of energies. In this case, each pulse in the pulse train is averaged out rather than a sharp profile. We examine how energy and time averaging of the electron wave packet affects the resolution of escaping electron pulses and study the energy dependence of the arrival time for each pulse in the ionisation train. An optimization condition for the laser pulse shape to generate narrow ionisation electron pulse in the train is obtained. The ionisation rates with various excitation energy are calculated also, which show the excitation to higher N Rydberg states will narrow the electron pulse as well.     

Equilibrium and structural studies of silicon(IV) and aluminium(III) in aqueous solution. II. Formation constants for the monosilicate ions SiO(OH)3− and SiO2(OH)22−. A precision study at 25°C in a simplified seawater medium

The hydrolysis of silicic acid, Si(OH)₄, was studied in a simplified seawater medium (0.6 M Na(Cl)) at 25°C. The measurements were performed as potentiometric titrations (hydrogen electrode) in which OH^? was generated coulometrically. The total concentration of Si(OH)₄, B, and log[H⁺] were varied within the limits 0.00075 ? B ? 0.008 M and 2.5 ? -log[H⁺] ? 11.7, respectively. Within these ranges the formation of SiO(OH)₃^? and SiO₂(OH)₂^2? with formation constants log β_?11(Si(OH)₄ ? SiO(OH)₃^? + H⁺) = ?9.472 ±0.002 and log β_?21(Si(OH)₄ ? SiO₂(OH)₂^2? + 2H⁺) = ?22.07 ± 0.01 was established. With B > 0.003 M polysilicate complexes are formed, however, with $\text{-}\text{log[H}{}^{\mathrm{+}}\text{] ? 10.7}$ their formation does not significantly affect the evaluated formation constants. Data were analyzed with the least squares computer program LETAGROPVRID.     

New finite-gap solutions for the coupled Burgers equations engendered by the Neumann systems

On the tangent bundle TS^N-1 of the unit sphere S^N-1, this paper reduces the coupled Burgers equations to two Neumann systems by using the nonlinearization of the Lax pair, whose Liouville integrability is displayed in the scheme of the r-matrix technique. Based on the Lax matrix of the Neumann systems, the Abel--Jacobi coordinates are appropriately chosen to straighten out the restricted Neumann flows on the complex torus, from which the new finite-gap solutions expressed by Riemann theta functions for the coupled Burgers equations are given in view of the Jacobi inversion.     

Food and energy in the diet of brown and rainbow trout from Lake Benmore,New Zealand

The diet of brown trout (Salmo trutta) and rainbow trout (S. gairdnerii) was studied in specimens from Lake Benmore, a deep, oligo‐trophic lake in South Island, New Zealand. Between November and July, both species fed mainly on small molluscs (Potamopyrgus antipodarum, Physa sp., and Gyraulus corinna) gleaned from the littoral weed beds. Energy values for the three species of mollusc were determined: P. antipodarum, 6000 J g^‐1; G. corinna, 5500 J g^‐1; Physa sp., 9800 J g^‐1. Potamopyrgus antipodarum yielded little energy to the fish, unless its shell broke during passage through the gut. Physa sp. was the most profitable mollusc, irrespective of shell breakage and Potamopyrgus antipodanim the least profitable. The mean energy value per snail for G. corinna and Physa sp. eaten by rainbow trout was 25–30% less than for snails eaten by brown trout, possibly because rainbow trout ingested empty shells from the sediment surface. Rainbow trout extracted about 20% more energy than brown trout from unbroken shells. In July, 84% of the brown trout switched to predation of common bullies, Gobio‐morphus cotidianus, probably as a result of bully reproductive behaviour. Rainbow trout did not show the same change, apparently because they were feeding in deeper water where few bullies were available. The low‐energy diet and its possible connection with growth rate are discussed.     

Estimating the parameters of pulsed sources from data on acoustic waves recorded in the atmosphere

The possibility of estimating the parameters of surface pulsed sources from data on acoustic waves recorded in the atmosphere is studied. Experimental values are given for peak pressure P ₊ of recorded acoustic signals, wave-profile area S ₊ in their positive phase, and length t ₊ of this phase, and the approximations of these parameters are obtained within wide ranges of source energy 10^–3 < E < 10¹⁰ kg TNT and scaled distances 1 < R/E ^1/3 < 4 × 10⁴ m/kg^1/3. Conventional methods of estimating the acoustic energy E according to data obtained from acoustic measurements in the atmosphere are analyzed, and ways to improve their accuracy are proposed. The influence of the type of explosions on the parameters P ₊, S ₊, and t ₊ of acoustic signals at long distances R/E ^1/3 > 500 m/kg^1/3 from explosions is shown.     

Computations of the energy flux to mixing processes via baroclinic wave drag on barotropic tides

The geographical distribution of barotropic to baroclinic transfer of tidal energy by baroclinic wave drag in the abyssal ocean is estimated. Using tidal velocities from a state-of-the-art numerical tidal model, the total loss of barotropic tidal energy in the deep ocean (between 70°S and 70°N and at depths greater than 1000 m) is estimated to be about 0.7 TW (M₂) corresponding to a mean value of the energy flux (e) of 2.4×10⁻³ W/m². The distribution of e is however highly skewed with a median of about 10⁻⁶ W/m². Only 10% of the area is responsible for more than 97% of the total energy transfer.To assess the possible influence of the relatively coarse bathymetry representation upon the present estimate, complementary calculations using better resolved sea floor topography are carried out over a control area around the Hawaiian Ridge. There are no major differences between the results achieved using the two different bathymetry databases. Fluxes of about 16 GW or 6×10⁻³ W/m² are computed in both cases, and the main contributions to the total fluxes originate in the same range of e-values and cover equally large parts of the total area.It is not clear whether the present model is valid at flat or subcritical bottom slopes. However, for the Hawaiian region, only 2% of the total energy flux as calculated in the present study originates in areas of critical and subcritical slopes.     

南极西北威德尔海上层海洋湍流混合研究

Turbulent mixing in the upper ocean(30-200 m) of the northwestern Weddell Sea is investigated based on profiles of temperature,salinity and microstructure data obtained during February 2014.Vertical thermohaline structures are distinct due to geographic features and sea ice distribution,resulting in that turbulent dissipation rates(ε) and turbulent diffusivity(K) are vertically and spatially non-uniform.On the shelf north of Antarctic Peninsula and Philip Ridge,with a relatively homogeneous vertical structure of temperature and salinity through the entire water column in the upper 200 m,both ε and K show significantly enhanced values in the order of O(10~(-7))-O(10~(-6)) W/kg and O(10~(-3))-O(10~(-2)) m~2/s respectively,about two or three orders of magnitude higher than those in the open ocean.Mixing intensities tend to be mild due to strong stratification in the Powell Basin and South Orkney Plateau,where s decreases with depth from O(10~(-8)) to O(10~(-9)) W/kg,while K changes vertically in an inverse direction relative to s from O(10~(-6)) to O(10~(-5)) m~2/s.In the marginal ice zone,K is vertically stable with the order of10~(-4) m~2/s although both intense dissipation and strong stratification occur at depth of 50-100 m below a cold freshened mixed layer.Though previous studies indentify wind work and tides as the primary energy sources for turbulent mixing in coastal regions,our results indicate weak relationship between K and wind stress or tidal kinetic energy.Instead,intensified mixing occurs with large bottom roughness,demonstrating that only when internal waves generated by wind and tide impinge on steep topography can the energy dissipate to support mixing.In addition,geostrophic current flowing out of the Weddell Sea through the gap west of Philip Passage is another energy source contributing to the local intense mixing.     

Assessing waterbird habitat use in coastal evaporative systems using stable isotopes (δC, δN and δD) as environmental tracers

Isotopic patterns of biota across salinity gradients in man-made evaporative systems could assist in determining the use of these habitats by animals. Here we report δ¹³C, δ¹⁵N and δD measurements of a euryhaline fish, the Mediterranean toothcarp (Aphanius fasciatus), inhabiting a range of salinities in the Thyna saltworks near Sfax (Tunisia). The contribution of these salinity niches to egg formation of two typically piscivorous bird species breeding in the area and feeding within saltworks, Little Tern (Sternula albifrons) and Little Egret (Egretta garzetta), was inferred trough a triple-isotope (δ¹³C, δ¹⁵N and δD) Bayesian mixing model. Isotopic trends for fish δ¹⁵N and δD across the salinity gradient followed the equations: δ¹⁵N = e^{(1.1 + 47.68/Salinity)} and δD = −175.74 + Salinity + Salinity²; whereas fish δ¹³C increased as salinity rose (δ¹³C = −10.83 + 0.02·Salinity), after a sudden drop in fish isotopic values for salinities >60 (Practical Salinity Scale) (average fish δ¹³C for salinities <60 = −5.92‰). Both bird species fed largely on low hypersalinity ponds (salinity = 43; average contribution = 37% and 22% for Little Egrets and Little Terns, respectively), although the use of intermediate hypersalinities (salinities 63 and 70) by Little Terns also occurred (16% and 21%, respectively). Isotopic patterns across salinity gradients allow the use of isotopic measurements to inform studies of habitat occupancy within evaporative systems and provide further insights into how wildlife communities interact with them.     

Space-time variability of the field of mechanical energy transfer from the atmosphere to the Indian Ocean

An analysis of the spatial and temporal variability of the field of mechanical energy transfer (MET) from the atmosphere into the ocean is based on a separate numerical simulation of evolution for the terms of source function for a wind-wave model conducted in the Indian Ocean area for the period 1998 to 2009. The MET field is described by two integral values calculated per unit area: the total rate of energy flux from the wind to waves, I _E (x, t), and the rate of energy-loss flux for the wind waves, D _E (x, t). To solve this problem, the wind field W(x, t) is used, downloaded from the NCEP/NOAA archive [1], and the fields I _E (x, t) and D _E (x, t) were calculated using the numerical model WAM [2] with the modified source function proposed in [3]. Maps for the fields I _E (x, t) and D _E (x, t) were obtained by calculations with different scales of the space-time averaging, extreme and average values of the MET were found, seasonal and interannual variability was estimated, and the 12-year trend for several mean quantities was obtained.     

Nd3+ :Gd3 Sc2 Al3 O12 晶场能级及拟合

Nd³⁺ :GSAG是性能优良的942 nm激光晶体.用提拉法成功生长Nd³⁺ :GSAG单晶,研究其室温透射光谱,辨认位置高达29967 cm^-1的68个Nd³⁺晶场能级.对这些能级拟合了自由离子及晶场Hamilton参量,拟合标准偏差为16.7 cm^-1,表明实验与计算能级符合很好.获得的Hamilton参量可用于计算Nd³⁺ :GSAG中Nd³⁺的     

Power resource estimate of ocean surface waves

The distribution of wave energy and power as functions of longitude and latitude are presented for the Northern Hemisphere at 12Z, October 2, 1975. Both the large peak of the distribution in the Atlantic Ocean and the smaller peak in the Pacific Ocean are found to be at longitudes towards the eastern end of the ocean basins. This ‘eastern accumulation’ of wave energy and power offers interesting contrast to the western intensification of currents. Distribution of wave power with latitude shows peaks of wave power in the mid-latitudes. The total surface wave energy in the seas of thw world for the same time is estimated to be 1600 × 10¹⁵ J. The corresponding total wave power estimate is 90 × 10¹⁵ W. The rate of renewal of wave power is estimated to bs 10¹²–10¹³ W, about the present level of world power consumption.     

Energetics of lateral eddy diffusion/advection：Part Ⅰ. Thermodynamics and energetics of vertical eddy diffusion

Two important nonlinear properties of seawater thermodynamics linked to changes of water density, cabbeling and elasticity(compressibility), are discussed. Eddy diffusion and advection lead to changes in density; as a result, gravitational potential energy of the system is changed. Therefore, cabbeling and elasticity play key roles in the energetics of lateral eddy diffusion and advection. Vertical eddy diffusion is one of the key elements in the mechanical energy balance of the global oceans. Vertical eddy diffusion can be conceptually separated into two steps: stirring and subscale diffusion. Vertical eddy stirring pushes cold/dense water upward and warm/light water downward; thus, gravitational potential energy is increased. During the second steps, water masses from different places mix through subscale diffusion, and water density is increased due to cabbeling. Using WOA01 climatology and assuming the vertical eddy diffusivity is equal to a constant value of 2×103 Pa2/s, the total amount of gravitational potential energy increase due to vertical stirring in the world oceans is estimated at 263 GW. Cabbeling associated with vertical subscale diffusion is a sink of gravitational potential energy, and the total value of energy lost is estimated at 73 GW. Therefore, the net source of gravitational potential energy due to vertical eddy diffusion for the world oceans is estimated at 189 GW.     

Metabolic loss of mass in glass eels at different salinities according to their propensity to migrate

Eel facultative catadromy is not clearly understood. Initial work suggested a possible control by energy content and energy expense in young stages. The present work aimed to better understand the mechanisms involved, by studying the influence of the salinity rearing environment in the loss of mass and therefore on fish energy and migration. Glass eels (Anguilla anguilla L.) caught on the Atlantic coast were identified according to their rheotactic response to the dusk signal, and thus to their propensity to migrate which can be low (sedentary, M⁻ fish) or high (flow-wise catches in early night, M⁺ fish). M⁺ and M⁻ fish were individually placed at different salinities (0, 10 or 30) for 28 days in small containers equipped with shelters. Individual wet mass and pigmentary stage were determined on Day 1 and Day 28. In addition, dry mass and percent dry mass were measured on a sub-sample of 30 fish randomly chosen on Day 1, and on all fish on Day 28. There was no difference in the loss of mass linked to their adaptation to salinity between M⁻ and M⁺ fish, and so the results do not support the link between migratory behaviour and salinity tolérance (or to a larger extent osmoregulation). However, M⁻ fish lost more wet mass than M⁺ fish irrespective of the salinity, maybe because of a higher standard metabolism, which suggests that glass eels prone to loose more energy might choose to settle at sea or in estuary. In addition, the highest percent dry mass after 28 days in seawater associated to the highest loss of mass in 28 days in seawater does not support a higher energy cost of osmoregulation at sea.     

Sorption of yttrium and rare earth elements by amorphous ferric hydroxide: Influence of pH and ionic strength

The sorption of yttrium and the rare earth elements (YREEs) by amorphous ferric hydroxide at low ionic strength (0.01 M ≤ I ≤ 0.09 M) was investigated over a wide range of pH (3.9 ≤ pH ≤ 7.1). YREE distribution coefficients, defined as _iK_Fe = [MS_i]_T / (M_T[Fe³⁺]_S), where [MS_i]_T is the concentration of YREE sorbed by the precipitate, M_T is the total YREE concentration in solution, and [Fe³⁺]_S is the concentration of precipitated iron, are weakly dependent on ionic strength but strongly dependent on pH. For each YREE, the pH dependence of log _iK_Fe is highly linear over the investigated pH range. The slopes of log _iK_Fe versus pH regressions range between 1.43 ± 0.04 for La and 1.55 ± 0.03 for Lu. Distribution coefficients are well described by an equation of the form _iK_Fe = (_Sβ₁[H⁺]^− 1 + _Sβ₂[H⁺]^− 2) / (_SK₁[H⁺] + 1), where _Sβ_n are stability constants for YREE sorption by surface hydroxyl groups and _SK₁ is a ferric hydroxide surface protonation constant. Best-fit estimates of _Sβ_n for each YREE were obtained with log _SK₁ = 4.76. Distribution coefficient predictions, using this two-site surface complexation model, accurately describe the log _iK_Fe patterns obtained in the present study, as well as distribution coefficient patterns obtained in previous studies at near-neutral pH. Modeled log _iK_Fe results were used to predict YREE sorption patterns appropriate to the open ocean by accounting for YREE solution complexation with the major inorganic YREE ligands in seawater. The predicted log _iK_Fe′ pattern for seawater, while distinctly different from log _iK_Fe observations in synthetic solutions at low ionic strength, is in good agreement with results for natural seawater obtained by others.