厦门文昌鱼人工繁殖和幼虫发育及其变态的研究

用组织学和胚胎学方法对厦门国家级自然保护区文昌鱼的生殖季节、胚胎发育和幼虫培育进行详细研究,结果表明,自然保护区文昌鱼生殖季节可分为两个繁殖时期,从6月初开始至7月初为繁殖高峰期,8和9月为繁殖小产期.观察人工繁殖得出,文昌鱼(Branchiostoma belcheri)产卵时间在傍晚19:00前后,可以观察到雌、雄文昌鱼的产卵和排精行为:雄性文昌鱼先离开沙,并跃出水面快速游动和排精,接着雌鱼也跃出水面,所有的卵通过破裂的性腺壁进入到围鳃腔并通过围鳃孔到水中受精,受精率在98.5%以上,还观察了文昌鱼幼虫发育并变态为幼鱼(长度为1.05～13.5mm)的全过程.     

汾渭地震带强震震源参数的确定

目的是计算汾渭地震强震的震源参数。所用的方法是根据断裂力学的有关公式分析断裂扩展过程中应力和位移的变化,计算结果表明地震多数是在低初始应用作用下发生的（大约１００×１０＾５Ｐａ）,而且该方法在原理上是可行的。     

Love Numbers And Elastic Energy Of Deformation For Venus

Love numbers of second order of Venus are calculated with resolving fundamental differential equations of elastic body according to the parameters of the density and the elasticity of material by means of the PVM94-01 Venus model. Meanwhile, the elastic energy of deformation of second order due to the tidal perturbation of the Sun and that due to rotational centrifugal potential are also calculated. The values of Love number provide a basis for model of internal structure of Venus. The numerical calculation of the elastic energy of deformation gives a magnitude evaluation of the perturbation terms to the Hamiltonian expressions in the study of dynamics of the elastic Venus. This revised version was published online in July 2006 with corrections to the Cover Date.     

Behaviour of hatchery‐reared and wild‐caught 4th and 5th stage American lobsters,Homarus americanus

Behavioural deficiencies in 4th and 5th stage hatchery‐reared lobsters were examined using time budget analysis and predator trials. Hatchery‐reared 4th stage lobsters were found to behave differently than wild‐caught lobsters and differences existed between hatchery‐reared lobsters from different sources. Local hatchery‐reared 4th stage lobsters spent less time on shelter and suffered higher predator rates in laboratory trials than both wild‐caught 4th stage and lobsters reared in a hatchery in Maine. Fifth stage hatchery‐reared lobsters spent significantly more time in shelter than their wild‐caught counterparts. These differences may be attributable to the lack of development of proper predator‐avoidance behaviour and need to be understood and corrected to maximise the effect of enhancement projects.     

Depth dependency of stress ratios during the sedimentation of NW Gyeongsang Basin (Cretaceous), southeast Korea: Estimate of stress parameters and timing of tectonic episodes

The natural stress state in the lithosphere consists of the vertical load and Poisson ratio, and then additional horizontal compression and extension (denoted by Δσ_H and Δσ_T, respectively) are assumed to be superimposed upon this gravitational stress field. The resulting stress state is composed of the maximum, medium and minimum stresses denoted by σ₁, σ₂, and σ₃, respectively. The stress ratio is given as Φ = (σ₂ − σ₃)/(σ₁ − σ₃). A linear relation is found between Φ or 1/Φ and the vertical load in wrench-faulting and extensional stress regimes, respectively. The slope and intercept of the linear relation result in the additional horizontal stresses and level of (average) paleo-surface, respectively. Stress ratio is also determinable by the stress tensor inversion of fault-slip data. The earliest tectonic event (T_1 Event) in the Cretaceous Gyeongsang Basin consists of coexisting E–W compression and N–S extensional faulting episodes. Plots of Φ or 1/Φ against the burial depth (or vertical load) display several linear trends: two clusters in extensional episodes, and two or three clusters in wrench-faulting episodes. Because Δσ_H is assumed to be null or negligible in the extensional regime, Δσ_T is determinable from the slopes of two linear clusters as being −2.5 to −4.0 MPa. In wrench-faulting episodes, the values of Δσ_H are given to be 61.6–101.4 MPa by applying determined additional horizontal extensions. Determined levels of average paleo-surfaces and those of syndepostional structures illustrate that more than five wrench-faulting or extensional episodes have occurred during the T_1 Event, whose active age, consequently, ranges from the Barremian to the Coniacian. This supports that the coexisting coaxial faulting episodes with the same extension may correspond to the alternation of wrench-faulting and extensional episodes.     

吉林省中,新生代陆缘弧发展演化阶段及其类型划分

依吉林省中，新生代陆缘弧发展演化特征，将其划分为三个发展演化阶段，即陆缘弧隆断阶段（Ｔ３－Ｋ１）陆缘弧隆拗阶段（Ｋ２－Ｋ２）和陆缘弧裂解阶段（Ｅ－Ｑ）。根据陆缘弧发展演化过程中的性状变化特点，陆缘弧类型可相应地划分在挤压型陆缘弧，盆岭型陆缘弧和裂解型陆缘弧。     

瞬态弹性波散射的变换域积分方程法

针对瞬态弹性波散射的问题,从弹性动力学问题的积分表示定理出发,采用Laplace变换的方法,得到了变换域内均质体位移场的积分方程表示;在此基础上推导了适合瞬态弹性波对异质体散射求解的变换域位移场积分方程。     

Torsional vibrations of elastic foundation on saturated media

A comprehensive analytical solution is developed to examine the torsional vibration of an elastic foundation on a semi-infinite saturated elastic medium for the first time. First, the governing equations of saturated media are solved by use of Hankel transform techniques. Then, based on the assumption that the contact between the foundation and the half-space is perfectly bonded, this dynamic mixed boundary-value problem can lead to dual integral equations, which are further reduced to the standard Fredholm integral equations of the second kind and solved by numerical procedures. Numerical examples are given at the end of the paper. The numerical results indicate that the response of the elastic foundation strongly depends on the material and geometrical properties of both the saturated soil-foundation system and the load acting on the foundation. In most of the cases, the dynamic behavior of an elastic foundation on saturated media significantly differs from that of a rigid plate bearing on the elastic half-space.     

基于应力偏量的横波纯应力逆时偏移成像方法

基于弹性波解耦延拓方程的波场分离方法不仅可以得到解耦的纵、横波质点振动速度场,还可以获得纵、横波应力场.针对横波纯应力场在利用单一分量成像时不具有明确物理意义的问题,本文将应力偏张量引入到横波应力场中,基于应力偏量第二不变量构建得到横波应力不变量并将其用于应力场的逆时偏移成像中,获得了可完整表征横波应力场的成像结果.模型试算表明,本文构建的横波应力不变量可以有效利用横波应力张量中的波场信息,并得到准确的弹性逆时偏移成像结果.

     

Time–frequency analysis to profile hydrological regimes: application to Haiti

Abstract

Comprehensive characterization of its flow rates is prerequisite to a proper understanding and water management of a given hydrological region. Several studies question the soundness of stationarity in time series and suggest the need for a quantification of the events and non-stationary features in flow rate time series. In this study, we combine statistical and time–frequency (TF) analyses to characterize and classify the flow rates of an understudied region, namely Haiti. Wavelet transforms and cyclostationarity analyses were combined with principal component analysis and hierarchical clustering to identify three groups of hydrological regimes in the country, suggesting similar management: (1) relatively stable flow rates with TF behaviour; (2) periodic and strongly seasonal flow rates; and (3) unstable flow rates. We argue that the TF methodology can yield additional information in regard to flow events and multiscale behaviour, even for short records. Flow rate characterization would benefit from the exhaustive approach described here.

EDITOR Z.W. Kundzewicz ASSOCIATE EDITOR E. Toth