组合空间曲线任意点三维大地坐标的算法研究

由解析曲线任意组合形式成的空间复杂曲线上任意点的大地坐标对于各种工程特别是线形工程的设计和施工具有重要意义，随着全站型仪器的广泛使用和依据坐标管理的需求日益增加，这一问题变得更加突出。本文在总结复杂线形特性和设计方法的基础上提出一种适合于计算机实现的通用算法及其程序编制技术。     

养殖对虾细菌性红体病的初步研究

从海南琼山患红体病的养殖南美白对虾(Penaeus vannamei)的肝胰脏和肌肉中分离出2株细菌，经纯化培养后的人工感染结果表明，该2株菌均为引起对虾红体病的细菌性病原菌；根据对这2株菌的形态及生理生化特征检测结果，确定这2株菌分别为溶藻弧菌(Vibrioalginolyticus)和副溶血弧菌(V.parahaemolyticus)。药敏试验表明，氮霉素、链霉素和庆大霉素等7种抗生素对抑制这2种致病菌具有良好作用。     

Design sensitivity analysis for vertical free vibration of hull girder

This paper presents a calculation method of derivatives of natural frequencies and mode shapes to parameters affecting vertical hull girder vibration based on design sensitivity analysis. The method premises free vibration analysis of hull girder using the transfer matrix method. Governing sensitivity equation is derived from the direct differentiation of state vector and transfer matrix to design variables. Derivatives of natural frequencies and mode shapes are determined after two trial calculations of the equation. By using the obtained derivatives, the changes of natural frequencies can be rationally and efficiently predicted in case of ship design modification and loading variation.     

Prediction of design wave loads of the ocean structure by equivalent irregular wave approach

The present study is employing the equivalent irregular wave approach to predict the wave loads for a ship encountering the worst sea state with respect to the critical dynamic loading parameter. Two different hydrodynamic numerical models, i.e. 3D pulsating source technique and 3D translating pulsating source technique, are applied to calculate the corresponding RAO of the ship moving in waves. Incorporating the RAO of the related physical properties, we can calculate the extreme value for the corresponding ship loading factor, which can be regarded as the worst sea state in the service lifetime of the ship. With the time and period of the occurrence of the corresponding extreme value, we can simulate the time history of the wave load in this period, which is so-called equivalent irregular wave approach. Comparing with the results calculated by the traditional equivalent regular wave approach, we find that the equivalent irregular wave approach can simulate the corresponding wave load more realistic, especially for dynamic pressure. Using the equivalent irregular wave approach can offer the effective and practical base for the ship structural analysis.     

The effect of directionality on extreme wave design criteria

Sea state design criteria for offshore facilities are frequently provided by direction. For example, it is typical for return-period values of the significant wave height to be specified for each of eight 45° sectors in addition to the omni-directional case. However, it is important that these criteria be consistent so that the probability of exceedance of a given wave height from any direction derived from the directional values is the same as for the omni-directional value. As recently demonstrated by Forristall it is not sufficient simply to scale the directional values so that the value of the wave height from the most severe sector is the same as the omni-directional value.We develop an approach for establishing appropriate directional criteria and an associated omni-directional criterion for a specific location. The inherent directionality of sea states is used to develop a model for the directional dependence of distributions of storm maxima. The directional model is applied to the GOMOS data, and the distributional properties of the 100-year significant wave height are estimated and the implications for design discussed. An objective risk-cost approach is proposed for optimising directional criteria, while preserving overall reliability. Simulation studies are performed, using realistic extreme value assumptions, to quantify the uncertainties.     

An Improved Simplified Method for Predicting the Hydroelastic Response of Mat-Like VLFS

Very Large Floating Structures (VLFS) have received considerable attention recently. Efficient and accurate estimation of their hydroelastic responses in waves is very important for the design. The most efficient approach would obviously be the analytical one. Within the category of analytical approaches, the simplified method proposed by Ohkusu and his colleague are of special characteristics. However, when one studies their methods, several questions arise. The purpose of this paper is to critically study the simplified methods proposed by Ohkusu and his colleague in order to answer these questions. Some problems in their original methods have been found and possible improvements are suggested. It is concluded that the improved simplified method using the same idea of Ohkusu and his colleague could provide a reasonable estimate of the hydroelastic response of mat-like VLFS in a certain range of incident angles of waves.     

V5-2000大地电磁测深仪文件头数据格式研究

V5-2000大地电磁测深仪由于其功能强、轻便、勘探范围大等特点,在国内已得到了广泛应用,但其后期数据解释软件却显得相对薄弱。要想解决解释软件的问题,首先所面临的是测量数据的格式问题。由于其保存的测量数据为特殊格式,为了便于对V5-2000测量数据进行后期处理与分析,这里对V5-2000测量数据的特殊数据格式进行了剖析,并用现今流行的,面向对象化的VB6.0编程语言,编写了相关读取及修改程序,以作为下一步的后期数据解释软件开发之基础。     

基于智能遗传算法和Otsu法的多目标图像分割方法

为了克服传统遗传算法在优化多目标图像分割参数时易陷入局部收敛和搜索效率低的缺陷,本文提出一种基于智能遗传算法和Otsu法的多目标图像分割方法,并将它应用于航空影像的分割。实验结果表明,本文提出的算法比传统遗传算法可以更加快速、更稳定地获取图像分割的最优阈值。     

Site effects close to structural lineaments in eastern Sicily (Italy)

This paper analyses site effects that are applied to compute the H/V spectral ratio close to structural lineaments. Aseismic creep and seismic creep have been examined. The lineaments are located in different types of volcanic soil. The aim of the work is to verify the possibility of fault-guided seismic waves within the structures, which behave as a waveguide for trapped waves.

The measurements of ambient noise were carried out along profiles crossing the structures, and the standard Nakamura technique was applied to calculate the spectral H/V ratio. It was observed that horizontal components of ground motion were found to be significantly amplified within the shear zone.