Statistic Analysis of the Annual Extreme Wave Parameters for the Coast of China

- According to the need of project design for offshore engineering and coastal engineering, this paper statistically analyses the annual extreme data of waves acquired at 19 observation stations along the coast of China. Five kinds of distribution curves are adopted: Pearson Ⅲ(P-Ⅲ), Log-Extreme I (LE), Log-Normal(LN), Weibull(W) and Exponential r(Eг) to check the adaptability to the long-term distribution of annual extreme of wave in the China Sea areas. The New Curve Fittling Method (NFIT) method and Probability Weighted Moments (PWM) method are used to estimate the distribution parameters and thereby to derive the design wave parameters with different return periods at 19 observation stations. The test results show that by combining Eг distribution and NFIT parameter estimation and optimum seeking by computer, the design wave parameters can be estimated with high accuracy, high speed and high efficiency, and the randomness of the estimated results can be avoided.     

Computation of Wave Refraction-Diffraction with Error Vector Propagation Method

After modifying the basic computation model made by Panchang (1988), the error vector propagation (EVP) method has been adopted to compute the combined effects of water wave refraction and diffraction in the presence of reflection boundary. The results show that the present method is successful in restraining the noise in Panchang's solution. Compared to other numerical methods for the mild-slope wave equation, EVP method can both consider the influence of reflection and save computer memory and computing time.     

Experimental and Theoretical Investigations of Mist Lift Cycle

A rectangular mist lift tube of 20 m effective height was constructed to investigate the mist generation and up flow processes with various temperatures, pressures and mass flow rates of the incoming hot water through two different mist generation plates. Parameters such as temperature, pressure and dryness of the two phase mixture at six different heights of the lift tube as well as the lift mass flow ratio were measured and analysed. A theoretical analysis was made based on simplified one dimensional model of two-velocity-two-phase flow. The calculated results were discussed regarding temperature, pressure and dryness variations along the lift tube height and compared with the experimental results.     

再论MDCB地震监测仪的映震效果

分析了 Ｍ Ｄ Ｃ Ｂ 型地震监测仪在廊坊连续４２ 个月观测期间, 所记录的类地应力值、８ 方位异常值和异常频度等１４ 种电磁波地震前兆异常参数的动态趋势、方向性反映、临震变化与一定范围内一定强度地震的对应关系, 并得出了电磁波前兆异常参数与地震数量关系的初步结果。     

任重道远的地震预测研究

１９５６年,在全国１２年科学技术发展远景规划中,明确提出了地震预报的课题。１９５８年,当时中国科学院地球物理研究所以郭增建为首的的科研人员组成了“地震预报考查队”,赴甘肃和宁夏地区收集、了解１９２０年海原大地震大量的宏观前兆及地质条件等资料,奏响了我国现代地震预测研究的序曲。１９６６年３月８日,邢台发生６．８级强烈地震,这是新中国成立以后第一次造成人民生产财产巨大损失的破坏性地震。当天周恩来总理赶到邢台,并来到地震工作者中间,他说：“这次地震,代价极大,必须找出规律总结经验,希望你们这一代能解决…     

Prediction of Siltation in the Downstream Approach Channel of Tidal Locks

Silt deposition occurs in the downstream approach,channel of the tidal lock as in a closed channelor excavated dock basin.It is often difficult to calculate or predict siltation because of complex flow and sedi-ment conditions and many other affecting factors.In this paper,the characteristics of flow movement in theapproach channel(including its mouth)of the tidal lock are analyzed,the basic laws of sediment movementand siltation mechanism are investigated,the conditions for three types of siltation(circumfluence siltation,density flow siltation and slow flow siltation)are discussed,and corresponding calculating formulas are pro-posed.A practical example shows that the difference between measured and calculated results is small,indi-cating that the present calculating methods could be used in design and management of practical engineeringprojects.     

Numerical Tidal Current Modeling Using Fine Boundary Fitted Grids for Tidal Flats

Fine grids with small spacing in boundary-fitted coordinates are normally used to treat thecomputation of fluid dynamics for estuarine areas and tidal flats.However,the adoption of Cartesian com-ponents of velocity vectors in this kind of non-orthogonal coordinates will definitely result in a diffculty insolving implicitly the transformed momentum equations,and also complicate the wet-dry point judgementused for flood areas.To solve this problem,equations in terms of generalized contravariant velocityvectors in curvilinear coordinates are derived in the present study,by virtue of which,anAlternative-Direction-Implicit numerical scheme in non-orthogonal grids would then be easily obtained,and wet-dry point judgement would as well be largely simplified.A comparison is made between the explic-it scheme and implicit scheme,showing that the present model is accurate and numerically stable for com-putations of fluid dynamics for estuarine areas and tidal flats.     

STUDY ON SEA ICE WITH GMS REAL-TIME DATA

By use of GMS-4 infrared brightness temperature and visible albedo data from January toFebruary in 1995,the method for extracting of sea ice parameters is developed.The digital remotesensing picture is obtained on Liaodong Bay.Based on the difference in physical properties betweenice and water,a criterion distinguishing ice from water is set up.Ice thickness has been calculatedaccording to the relationship between ice thickness and brightness as well as albedo.Iceconcentration is retrieved due to the difference on albedo between ice and water.The resultsindicate that the accuracy of ice-water distinguishing is 84.8%,the errors of ice thickness and iceconcentration are 3.8 cm and 22%,respectively.     

On stress-forecasting strategy of earthquakes from stress buildup, stress shadow and stress transfer （SSS） based on numerical approach

Global Positioning System(GPS) and Interferometric Synthetic Aperture Radar(InSAR),used for monitoring crust deformation,are found to be very promising in earthquake prediction subject to stress-forecasting.However,it is recognized that unless we can give reasonable explanations of these curious precursory phenomena that continue to be seren-dipitously observed from time to time,such high technology of GPS or InSAR is difficult to be efficiently used.Therefore,a proper model revealing the relation between e...     

Decline of groundwater table in Beijing and recognition of seismic precursory information

This paper quantitatively analyzed groundwater table fluctuations caused by groundwater overdraft, and probed into the possibility of drawing earthquake precursory information from groundwater table variations on the background of groundwater overdraft. Main effect factors of groundwater regime in Beijing region include groundwater extraction and rainfall. The decline of groundwater table was directly related to regional groundwater overdraft. Using the method of correlation analysis, the paper analyzed the...