2个凡纳滨对虾全同胞家系在不同盐度下的生长比较

在1‰-40‰盐度范围内,设置9个盐度梯度(1‰、5‰、10‰、15‰、20‰、25‰、30‰、35‰、40‰),比较不同盐度对2个具有不同遗传背景凡纳滨对虾Litopenaeus vannamei全同胞家系的影响.结果表明,盐度对2个凡纳滨对虾家系的影响存在较大差异.对虾家系B03在10‰-40‰盐度范围内,体长、体重差异不明显,成活率较高;对虾家系B08在1‰-40‰盐度范围内,体长、体重、增长率具有明显的变化规律,从盐度1‰到15‰逐渐升高,15‰以后逐渐减小.对虾家系B03的成活率整体高于B08的成活率,2个家系均难以适应盐度为1‰和5‰的水体.研究为凡纳滨对虾的家系选育提供一定的数据支持.     

扩边尺度对重力异常分层分离处理的影响——以插值切割法为例

以插值切割法为例,对理想模型在地表的重力异常数据进行不同尺度的扩边,并对扩边后的数据进行不同深度层源的切割分离.基于分离后的结果,从不同扩边尺度、不同深度层源的重力异常差异、扩边尺度与重力场源分离误差的角度研究扩边尺度对重力异常分层分离处理的影响.结果表明:1)理想模型数据区域的边界效应与扩边尺度、切割分离深度、异常的...     

The impact of slope length on the discharge of sediment by rain impact induced saltation and suspension

Simulations using a mechanistic model of raindrop driven erosion in rain‐impacted flow were performed with particles travelling by suspension, raindrop induced saltation and flow driven saltation. Results generated by both a high intensity storm, and a less intense one, indicate that, because of the effect of flow depth on the delivery of raindrop energy to the bed, there is a decline in sediment concentration, and hence soil loss per unit area, with slope length when particles are transported by raindrop induced saltation. However, that decline is reversed when the critical velocities that lead to flow driven saltation are episodically exceeded during an event. The simulations were performed on smooth surfaces and a single drop size but the general relationships are likely to apply for rain made up of a wide range of drop size. Although runoff is not always produced uniformly, as a general rule, flow velocities increase with slope length so that, typically, the distance particles travel before being discharged during an event increase with slope length. The effect of slope length on soil loss per unit area is often considered to vary with slope length to a power greater than zero and less that 1·0. The simulations show that effect of slope length on sediment discharge is highly dependent on the variations in runoff response resulting from variations in rainfall duration‐intensity‐infiltration conditions rather than plot length per se. Consequently, predicting soil loss per unit area using slope length with positive powers close to zero when sheet erosion occurs may not be as effective as commonly expected. Erosion by rain‐impacted flow is a complex process and that complexity needs to be considered when analysing the results of experiments associated with rain‐impacted flow under both natural and artificial conditions. Copyright © 2009 John Wiley & Sons, Ltd.     

纤维加筋土中单根纤维的拉拔试验及临界加筋长度的确定

纤维加筋土物理力学性质主要受纤维与土界面之间作用力大小的控制,了解界面的微观力学行为对研究纤维加筋土的机制及工程应用具有重要意义。首先,利用自行设计的纤维拉拔试验装置,对不同含水率和不同干密度的土样进行了单根纤维的拉拔试验,测试并计算了单根纤维与土接触面之间的剪切强度和残余剪切强度,分析了含水率和干密度大小对它的影响。结果表明,设计的试验装置和试验方法能较好地进行单根纤维的拉拔试验,具有较高的准确性和精度。获得了纤维加筋土中界面剪切强度和残余强度与土样含水率和干密度之间的定量关系;分析拉力-位移曲线表明,加筋土中纤维的拉拔特性取决于筋土界面的力学行为,曲线的形状受含水率和干密度的影响不明显。最后,利用测得的筋土界面强度导出了纤维加筋的临界长度。     

利用小波变换分析随机-均匀介质尺度特征

为研究复杂非均匀介质中非均匀体的尺度特征,建立了随机-均匀介质模型,利用小波变换方法,对随机-均匀介质3种地震波(直达波、散射波和反射波)的尺度特征进行了分析和研究。结果表明：3种地震波表现出不同的尺度特征,直达波表现出大尺度特征,散射波次之,反射波具有小尺度特征;随着模型参量横向自相关长度的增大,直达波的最佳尺度呈下降趋势,散射波和反射波的最佳尺度呈上升趋势。研究结果为利用小波变换分析地震剖面中地震波以及非均匀体的尺度特征提供了参考。     

Calculation of maximum allowable free span length and safety assessment of the DF1-1 submarine pipeline

The DF1-1 submarine pipeline was investigated using a dual-frequency side-scan sonar and a swath sounder system. More than a hundred scour pits under the pipeline were found, most of which have caused the span of the pipeline to increase and threatened its safety. The maximum allowable free span length (MAFSL) of the pipeline was determined through the limitations regarding maximum allowable stress under static or quasi-static loads and the onset of Vortex Induced Vibrations (VIV) under different hydrodynamic actions. The results show that the MAFSL under static conditions is 56 m. However, the MAFSLs are 30 m and 20 m under ordinary weather conditions and hurricane-induced currents for the 100-year return period, respectively, to avoid VIV as calculated by using the highest safety class factor. It is suggested that spanning pipelines longer than 20 m should be supported. Additionally, eight successive spans which may also threaten the pipeline were proposed. The most hazardous scour pits are along the pipeline section from KP42 to KP51.     

Distributions of Water Masses and Currents in Tachibana Bay, West of Ari-ake Sound, Kyushu, Japan

We have investigated the water mass distribution and circulation in Tachibana Bay, which is located in the junction area between Ari-ake Sound and Amakusa-Nada in western Kyushu, Japan. This was done to clarify the mechanism by which ghost shrimp larvae, originating from a sandflat of Amakusa-Shimoshima Island, are transported. Temperature and salinity data repeatedly obtained over the area of Tachibana Bay show that relatively low salinity water lies over northern part of the bay, while high salinity water lies over southern part of the bay. The location of the low salinity water margin tends to depend on the amount of rainfall several days before the observation. A large amount of rainfall makes a clear boundary between low and high salinity waters. Current velocity data indicate an eastward mean flow just north of Tomioka, northern tip of Amakusa-Shimoshima Island, and a clockwise mean flow approaching the Tomioka Bay sandflat, which should be suitable for the on-shore transport of the ghost shrimp postlarvae. Current measurements with shipboard ADCP just west of Hayasaki Strait, at the entrance of Ari-ake Sound, show that a westward tidal residual current tends to incline to the north, with evidence of a density current in the northern part of the western Hayasaki Strait.     

转基因技术在鱼类及对虾中的应用(英文)

作者对转基动物的出现背景及优点,转基因过程的基本程序,转基因鱼研究的现状,鱼类基因的大量克隆,基因启动子的快速分离技术,分析启动子活性的瞬时转基因测试,绿色荧光蛋白转基因鱼作为观赏鱼的潜力,转抗病基因的研究进展,转基因技术在对虾中应用的展望,作了较全面的叙述。     

A new ΔLOD series in monthly intervals (1892.0–1997.0) and its comparison with other geophysical results

Using the ΔT (integrated variation of the Earth's rotation measured in terestrial time) series (1891.5–1955.5) derived from lunar occultation observations and the UT1–UTC (universal time–coordinated universal time) series (1955.5–1997.5) of the Bureau International de L'Heure/International Earth Rotation Service, a new ΔLOD (variation of the length of day) series in monthly intervals from 1892.0 to 1997.0 is calculated. Using digital filtering, the interannual and decadal components of the ΔLOD series are separated and then compared with those inferred from other geophysical quantities. It is shown that, on the interannual time scale, atmospheric processes can play an important role in exciting astronomical ΔLOD. However, the main oscillation with a mean period of about 5.8 years and peak-to-peak amplitude of about 0.3 ms in the residuals of ΔLOD(Astr) −ΔLOD(Wind) for 1968.0–1997.0 suggests that about half of the amplitude in astronomical ΔLOD must be excited by other geophysical processes, while on the decadal time scale the atmospheric excitation is too small. Geomagnetic core–mantle coupling may be a plausible source of the excitation of ΔLOD on the decadal time scale, but the geomagnetic data are still insufficient and an improved model of core–mantle coupling is required. Received: 3 April 1998 / Accepted: 31 May 1999     

水泥粉喷桩荷载传递规律的试验研究

通过水泥粉喷桩的现场足尺试验,测试了极体的应力-应变关系,推算出极侧摩阻力、轴力变化曲线。结果表明,荷载沿桩身的传递有一定范围,桩体的变形、应力、侧摩阻力主要集中在临界桩长范围内,而各量变化梯度在浅部较大。桩侧摩阻力的发挥与极土相对位移有关。桩体破坏也发生在浅层,破坏形式为环向拉裂和桩体横向压碎。