Nonlinear tidal waves in a kind of estuary with gradually varying cross-section

-Nonlinear tidal waves in a kind of estuary are studied in the paper using one-dimensional nonlinear hydrody-namic equations with friction. The estuary has exponentially varying width B=B0 e-bx and uniform depth h. The one-dimensional hydrodynamic equations are solved by perturbation method. It was found that our solution included two special cases, Pelisenpeki's solution and Airy's solution. The former can be got by letting b=0 in our solutions, and the latter by setting 6 = 0 and f= 0 (f is linear frictional coefficient). In terms of the second-order solution, the physical mechanism of nonlinear tidal waves in estuaries with gradually varying cross-section is explored. It is shown that, under the assumption of linear friction coefficient, shallow water constituent waves consist of two parts, one is produced by shallow water nonlinear effect outside the estuary, the other is generated by shallow water nonlinear effect inside estuary. In addition, the physical mechanism of the residual tidal current and     

Numerical Study on Instantaneous Discharge of Unsorted Particle Cloud in Cross Flow

The mixing characteristics of particles such as dredged sediment of variable size discharged into cross flow are studied by a 3D numerical model, which is developed to model the particle-fluid two-phase flow. The Eulerian method with the modified k-ε parameterization of turbulence for the fluid phase is used to solve fluid phase, while a Lagrangian method for the solid phase (particles), both the processes are coupled through the momentum sources. In the model the wake turbulence induced by particles has been included as additional source term in the k-ε model; and the variable drift velocities of the particles are treated efficiently by the Lagrangian method in which the particles are tracked explicitly and the diffusion process is approximated by a random walk model. The hydrodynamic behavior of dumping a cloud of particles is governed by the total buoyancy of the cloud, the drag force on each particle and the velocity of cross-flow. The computed results show a roughly linear relationship between the displacement of the frontal position and the longitudinal width of the particle cloud. The particle size in the cloud and the velocity of cross flow dominate the flow behavior. The computed results are compared with the results of laboratory experiments and satisfactory agreement is obtained.     

One new species of free-living marine nematodes (Enoplida,Anticomidae, Cephalanticoma) from the Huanghai Sea

One new species of free-living marine nematodes Cephalanticoma filicaudata sp. nov. from the Huanghai Sea, China is described and illustrated. Cephalanticoma filicaudata sp. nov. is characterized by well developed cephalic capsule, three teeth at the anterior of oesophagus, excretory pore opens posterior to cervical setae, only two cervical setae per file, body length longer than 5 200 μm, tail long and no ventral-lateral seta between the supplement and the cloacal opening. Types are deposited in the College of Marine Life Sciences, Ocean University of China.     

大黄鱼病原弧菌拮抗放线菌的筛选与人工诱变

从厦门集美海滩底泥分离得到38株放线菌，用琼脂块法测定它们对大黄鱼病原弧菌-溶藻弧菌和副溶血弧菌的拮抗效果，选择两株拮抗效果较好的放线菌进行诱变，测定诱变后各菌株的抗菌效果，并选择抗菌效果较好的菌株进行第二次诱变，如此反复诱变3次，共得到97株放线菌，结果表明；38株放线菌中的22株对两株病原菌有一定的拮抗作用；用紫外线照射可以获得少量对两株病原菌拮抗作用加强的菌株。     

光诱鱿鱼浮拖网渔具渔法试验报告

1989－1999年开展光诱鱿鱼浮拖网渔具渔法研究的生产试验结果为：1998年生产试验86个夜（航次），总产量33．225t，其中鱿鱼产量为12．470t，占总产量的37．5％，总产值139000元，比同村光诱敷网的平均产量（31．62t）高5．1％左右。1999年生产试验80夜（航次），总产量54．66t，其中鱿鱼产量31．92t，占总产量的58．4％，总产值187000元。试验网产量比同村光诱敷网的平均产量（45．64t)增产19．76％，产值增加22．65％，鱿鱼产量占总渔获量的比例提高近10个百分点，投入产出比为1：1．684。取得了较好的试验结果，达到了预期试验目的。此外，文中还讨论了水上灯数量，网具规格和柔性网板等对生产效果和捕捞对象的影响及适应性情况，并建议开展光场强度及其分布的海上实测和光场强度对鱿鱼，趋光性鱼类的行为习性以及生长影响等试验研究，制定出光诱鱿鱼浮报网和敷网作业诱鱼灯数量和分布标准，以合理利用鱿鱼和中上层鱼类资源，实现可持续发展。     

A Note on Soil Structure Resistance of Natural Marine Deposits

It has been well documented that natural normally-consolidated marine soils are generally subjected to the effects of soil structure. The interpretation of the resistance of soil structure is an important issue in the theory study and engineering practice of ocean engineering and geotechnical engineering. It is traditionally considered that the resistance of soil structure gradually disappears with increasing stress level when the applied stress is beyond the consolidation yield stress. In this study, however, it is found that this traditional interpretation of the resistance of soil structure can not explain the strength behavior of natural marine deposits with a normally-consolidated stress history A new interpretation of the resistance of soil structure is proposed based on the strength behavior. In the preyield state, the undrained strength of natural marine deposits is composed of two components: one developed by the applied stress and the other developed by the resistance of soil structure. When the applied stress is beyond the consolidation yield stress, the strength behavior is independent of the resistance of soil structure.     

不同软基处理方法适用性比较

总结分析了国内外现有的软土地基处理的各种方法。通过对采用不同方法进行软基处理的工程实例处理效果的定量对比，发现不同软基处理方法的适用性差异很大，多数工程中仅用一种方法很难达到设计要求，而两种或多种方法联合则可望取得更好的效果。     

Mach Effect of Oblique Nonlinear Irregular Waves Interacting with Vertical Walls

Based on Hong‘s theory, previous random models, and a generalized expression suitable for FIT calculation, the interaction between irregular waves and vertical walls is numerically simulated. The results of simulation demonstrate that the wave energy changes with the incidence angle and the distance from the wall. Particularly, the Mach effect and the combined wave spectrum characteristics are analyzed in detail, which are significant in both theory and practice.     

一种推广的缓坡方程

从流体力学基本方程出发，假定水流的涡量和垂向流速分量小量，推导出考虑非均匀水流的推广的缓坡方程，该方程中包含了△h^2h项和（△hh)^2项。在方程中引入底摩擦项、风能输入项和非线性项，其中风能输入项的推导考虑了风浪与涌浪的区别，风流情况依据青岛海洋大学的风浪成长经验关系，涌浪情况依据Snyder等人的观测结果。经过上述推广后，得到综合考虑折射、绕射、反射、非均匀水流、底摩擦损耗、风能输入及波浪非线性的推广的缓坡方程。     

不同季节的企鹅珍珠贝游离珠植核效果比较

在雷州流沙港湛江海洋大学珍珠研究室实验基地分别于春、夏和秋季进行了企鹅珍珠贝游离珠植核实验。其中，春季插核的死亡率最低，为15.1％--16．2％，留核率最高，为10％左右：而夏季插核的死亡率最高，为63．56％，留核率也仅为2．22％：秋季插核的留核率最低，仅收珠1颗，留核率为0．35％，死亡率也较高，为54.4％。结果表明，春季是企鹅珍珠贝较适宜的插核季节。