Interactive computer graphics method for the combined interpretation of gravity and magnetic data

A program for computation of the gravity and magnetic anomalies associated with two-dimensional structures has been adapted for use in an interactive mode using a storage-screen CRT linked to a remote computer via standard telephone lines. This new program aids the user in developing a structural model that satisfies both magnetic and gravity observations. Examples are included to demonstrate the increased efficiency of interpretation using this low-cost graphics approach and to illustrate the detail of the model resulting from the compromise necessary to satisfy both potential-field data sets.     

Extreme dynamic, non-linear response of fixed platforms using a complete long-term approach

The general theoretical basis for application of the direct long-term approach to offshore structures with non-Gaussian response is outlined. The key to the method is the determination of the short-term response distribution. Special considerations should be taken, depending on the application, and the Weibull distribution with a special fitting procedure is suggested as a short-term probability model for fixed offshore platforms. The efficiency of the method is improved by introducing smoothing functions for the variation of the Weibull parameters with the seastate.

The method is applied to a jacket and jackup platform. The results show that smoothing functions increase the efficiency considerably. The design storm method compares well with the long-term results for the selected structures, but only the long-term approach yields realistic estimates of the design extreme response when both extreme and resonant seastates contribution to the 100-year response.     

User participation and fishery management performance within the pacific fishery management council

Fish populations have the potential to contribute to the long-term economic and social benefit of humans, but to do so they must be managed in ways which maintain ecological health. There are many ways that management performance can be assessed, but four measures are particularly pertinent to sustainability: equity, stewardship, regulatory resilience, and efficiency. A key factor in management performance is the process by which management tools are developed and implemented. One approach that has been recommended to improve performance is to structure the management process around user participation. The paper analyzes three case studies of user participation in ad hoc processes of Pacific groundfish management: the development of a license limitation program; an inter-gear sablefish allocation; and the development of a sablefish individual quota (IQ) program. The case studies illustrate the role played by participation in contributing to the equity, stewardship, resilience, and efficiency of the management process. The effect of user participation was mixed in the three cases, depending on the history of participation, the structure and process of participation, on resource conditions and on the characteristics of the program under consideration. Participation can contribute positively to fishery management performance when there is a history of collective decision-making, the time line is slow enough to allow a full consideration of the issues, educational possibilities are pursued and the condition of the resource allows equitable compromises.     

The Ocean Community

Development of ocean community systems relating to the Taiwan Strait Tunnel (TST) project, with regionalization and multistage approach is proposed. The purposes of these systems are to assist the development of coastal marine lands and harbor facilities and to develop connecting isolated islands into an organized community by means of embankment roadways, tunnels, bridges, ferryboats, and so on. The major aim of such an approach is to develop the isolated abandoned islands into useful land improvement, expand the forest, agriculture, and fishing industries and other resources to generate additional revenue to subsidize some of the cost for building the TST. This article points out the systems' importance, outlines the general procedures, and discusses a possible transportation network connecting islands with land; and the outlines development of the knowledge-based expert system computer program to be applied to the ocean community systems relating to the TST project.     

Lessons learned from ‘decentralized’ ICM: an analysis of Canada's Atlantic Coastal Action Program and China's Xiamen ICM Program

Integrated coastal management (ICM) is a management process used by stakeholders in decision making to determine how coastal areas will be used and what activities can take place in them. While many ICM Programs are national government initiatives, some ICM Programs are ‘decentralized’, managed by community groups or local governments. This paper describes the Atlantic Coastal Action Program (ACAP), an ICM Program in Atlantic Canada, and the Xiamen ICM Program, in Xiamen, China, and discusses their major differences. The most important difference between the two ICM Programs is that ACAP is a community-based program that uses a multi-stakeholder approach and consensus decision making, while the Xiamen ICM Program is managed by a coordinating office within a local government. After comparing the two programs, some general lessons learned about decentralized ICM from these case studies are noted. It is concluded that the appropriate use of either model for ICM depends on the cultural, economic and political environment of the program. However, stakeholder involvement, scientific consultation and the use of a detailed management plan are important components of any decentralized ICM program.     

The Ocean Community

Development of ocean community systems relating to the Taiwan Strait Tunnel (TST) project, with regionalization and multistage approach is proposed. The purposes of these systems are to assist the development of coastal marine lands and harbor facilities and to develop connecting isolated islands into an organized community by means of embankment roadways, tunnels, bridges, ferryboats, and so on. The major aim of such an approach is to develop the isolated abandoned islands into useful land improvement, expand the forest, agriculture, and fishing industries and other resources to generate additional revenue to subsidize some of the cost for building the TST. This article points out the systems' importance, outlines the general procedures, and discusses a possible transportation network connecting islands with land; and the outlines development of the knowledge-based expert system computer program to be applied to the ocean community systems relating to the TST project.     

基于GPRS的大地测量数据实时传输和处理系统的设计与实现

外业数据采集与内业处理检核的时空阻隔问题一直是制约大地测量数据生产效率的瓶颈,提出建立基于GPRS网络的大地测量数据的传输处理系统,详细设计了系统各模块的功能以及数据的传输控制方法,可实现外业端数据的实时、可靠传输和内业自动检核处理,提高大地测量数据生产的效率。     

A critical review of the CoastView project: Recent and future developments in coastal management video systems

This contribution provides a critical review of the CoastView project; a research program designed to develop and quantify video-derived Coastal State Indicators (CSIs) which simplify various aspects of coastal zone management including, coastal protection, navigation and recreation. This paper aims to provide a guide to future applied research projects of this kind. The research program implemented a ‘frame of reference’ methodology in order to effectively match research outcomes to the needs of end users and to facilitate communication within a consortium comprising both scientists and end users of the technology. Data derived from coastal video systems played a crucial role in defining CSIs which form a central component of the ‘frame of reference’ process. In general coastal video systems were demonstrated to be a very effective coastal management tool in all of the areas under investigation, uniquely providing data with excellent spatial and temporal resolution and coverage. Additionally, the ‘frame of reference’ ensured the appropriate match of science to the needs of the end user. However, even given these significant advances, the transfer of useful methodologies to applied tools is not guaranteed. The importance of providing simple, robust tools for delivering CSIs simply and efficiently to the coastal manager at the appropriate time-scale was recognised; ideally this should be completed within the timeframe of the research program. The acceptance of new methodologies is greatly enhanced by demonstrating them alongside more established techniques and other data sources, clearly showing the advantages, reliability and accuracy of the new approach.     

Technical Issues and Recommendations Related to the Installation of Continuous GPS Stations at Tide Gauges

Geodesists around the world have begun installing continuous GPS (CGPS) stations at tide gauges in order to determine the exact position of these tide gauges and, in particular, the vertical velocity of the land or the seafloor underlying each tide gauge. The goal is to make these measurements in a well-defined global reference frame. The scientific applications of these measurements include the calibration of satellite altimeters and the removal of crustal motion signals from long time series of sea level change. In this article we focus on the technical issues associated with this agenda, including site selection, instrumentation, monumentation, ancillary measurements, and the tide gauge leveling program. There is no universally best approach to building CGPS stations at tide gauges. Therefore we emphasize the various trade-offs that typically occur, and give general recommendations and rules of thumb based on recent installations and experience. Additional information can be found at the CGPS@TG website.     

Technical Issues and Recommendations Related to the Installation of Continuous GPS Stations at Tide Gauges

Geodesists around the world have begun installing continuous GPS (CGPS) stations at tide gauges in order to determine the exact position of these tide gauges and, in particular, the vertical velocity of the land or the seafloor underlying each tide gauge. The goal is to make these measurements in a well-defined global reference frame. The scientific applications of these measurements include the calibration of satellite altimeters and the removal of crustal motion signals from long time series of sea level change. In this article we focus on the technical issues associated with this agenda, including site selection, instrumentation, monumentation, ancillary measurements, and the tide gauge leveling program. There is no universally best approach to building CGPS stations at tide gauges. Therefore we emphasize the various trade-offs that typically occur, and give general recommendations and rules of thumb based on recent installations and experience. Additional information can be found at the CGPS@TG website.     

海上浮体系泊缆自动化设计方法研究

随着智能化研究成为当今科技发展的热点,结合智能优化算法的浮体系泊系统自动化设计成为一个将现代方法应用于传统工程领域并提高设计效率的研究对象。针对浮体的系泊系统,以悬链线式系泊方式为研究对象,分析得出了系泊缆与不同选材参数之间的规律,建立系泊系统自动化设计方法,选用遗传算法作为算法基础,实现方案的智能优选,进行了有效的探索研究;开发了系泊系统自动化设计的自主程序,完成了典型的单根系泊缆的单点系泊系统以及多段组成风分布式系泊系统的研究,验证了方法的可行性,为系泊系统的自动化设计这一技术问题提供了解决方法与工程的应用手段。     

Acoustic stereo images of the bottom surface

In order to enhance the efficiency of the interpretation of surface images obtained with a side scanning sonar, it is proposed to supplement the standard processing software with a program for obtaining acoustic stereo images. Examples of such images synthesized with this program using the data of a bottom sonar survey with a side scanning sonar and an echo sounder are presented. The cases are considered when the information on the bottom relief contained in sonar images obtained with a standard side scanning sonar or its modifications can be used instead of the data of an echo sounding survey.     

Ultimate Strength of Ship Plating under Axial Compression

The failure of a ship hull girder is governed by buckling and plastic collapse of the deck, bottom and side shell steel stiffened plates. The stiffened steel plating in ships is generally subjected to both in-plane and out-of-plane loading and is more important to understand the characteristics of these panels under buckling. Tests are reported on the collapse load of stiffened plates with and without cutout and with reinforced cutout under uniaxial compression. A generalized computer program for the semi-analytical solutions proposed by various investigators based on strut approach and orthotropic plate approach, and a finite element analysis program based on orthotropic plate approach are developed. The panels are also analysed using the finite element analysis software ANSYS. An approximate method based on strut approach is proposed to calculate the collapse load of stiffened plates with cutouts and initial imperfections. The reduction in strength of the panels due to the presence of square cutout, rectangular cutout and increase in strength due to reinforcement around rectangular cutout are calculated based on the test results. Comparisons are made between the test results and predictions based on semi-analytical solutions and finite element analyses, and the uncertainty parameters calculated are discussed. Based on this study it is concluded that the cutout can be reinforced with a maximum increase in strength up to 19% for plate initiated failures.     

浮标用数字式气压传感器研究

研究了振筒式数字气压传感器的工作原理并进行了程序设计。在程序设计中采用了二元函数分段抛物线插值修正非线性和线性插值修正温度误差的 方法,这在数字式传感器的研制中有较普遍的意义。     

Compliant vertical access riser assessment: DOE analysis and dynamic response optimization

As a contribution to the deepwater oil and gas industry, this paper addresses the use of optimization techniques together with a design of experiments (DOE) assessment, as a way of automating the design of compliant vertical access risers (CVARs) while also leading to an optimal riser configuration based on some desired efficiency parameters. The CVAR is a new riser concept that can improve the structural performance of the production system and also provide several operational benefits. The DOE is a statistical technique that provides an objective measure of how design parameters are correlated and the effective contribution of each one at the riser performance. Based on such a study some general conclusive remarks on the global behavior of CVAR will be presented. Such results also play an important role for the optimization process, as it can highlight significant design parameters, enabling design simplifications and efficiency improvement. For optimization assessment, geometric parameters are taken as the design variables and the design constraints consider both structural integrity and operational criteria. A multi-objective approach is considered taking into account the structural performance and geometric criteria. Optimal solution is obtained by NSGA-II method. Extreme and operational environmental conditions of a Brazilian offshore field are used as the base case.     

考虑翘曲应力的半潜平台扭转极限强度计算方法研究

半潜平台由于结构和受力复杂,目前主要采用非线性有限元整体模型计算其扭转极限承载力,存在建模和计算时间较长、精度较差和不易收敛等问题。一方面进行半潜平台的整体有限元模型的简化研究,提高其计算效率和收敛性;另一方面基于薄壁杆件理论,将该半潜平台截面简化为单壁室截面计算其翘曲应力,提出了基于一跨模型且考虑翘曲应力影响的半潜平台约束扭转极限强度计算的简化增量迭代方法,并编制了相应的计算程序。计算结果表明,所提简化增量迭代方法计算精度较高,能很好地反应翘曲应力对半潜平台约束扭转极限强度的影响,大幅减少了计算约束扭转极限强度的时间,可用于半潜平台的设计。     

Steady-state analysis of undersea cables

A numerical solution and computer program developed to analyse undersea flexible cable problems is presented. The cable is subject to hydrodynamic loads from a surrounding fluid medium. The object is to determine the cable profile and tensile forces developed. The cable equations and boundary conditions result in a classical two-point boundary value problem. An iteration ‘shooting method’ is used for solution. The program has been written to analyse a class of towing and anchoring problems. However the analysis is general and applicable to most steady-state cable problems.     

HY-1卫星资料植被信息提取应用系统的研制

为了最大限度发挥我国发射的第一颗海洋卫星宝贵资料的作用，本项目以长江口为研究示范区，利用第四代可视化计算机语言IDL为工具，研究开发了HY—1卫星资料的植被信息提取应用系统。该软件不但具有通用的图象信息读取、彩色合成、边缘增强、平滑处理等信息增强功能，还具有不同植被指数计算、植被指数基础上的监督和非监督分类等专用功能。基本能够满足利用HY—1卫星数据提取植被信息的要求。目前，该系统经过试验运行和实况验证，取得了良好的运行效率和精度较高的植被遥感信息提取、分类结果。从而为有效应用HY—1卫星数据进行植被资源信息的提取提供了重要技术保证。     

Breaking wave prediction with boundary elements and finite volumes for use with small boat capsize studies: Convergence and resource requirements

The prediction of extreme breaking waves forms the foundation of many fields of research. The authors have recently completed a study in the capsize and re-righting of sailing yachts using breaking wave prediction to enhance experimental results. As breaking wave prediction is only the beginning of any research program a prediction method is required to be both accurate and computationally inexpensive. This paper describes the investigation of two methods varying in computational demand. It has been concluded that a non-linear free surface boundary element method is immediately realisable with application to a research program requiring a large number of predicted waves. A finite volume approach is realisable, but its engineering application across numerous waves is difficult.     

Fishing institutions: Addressing regulative,normative and cultural-cognitive elements to enhance fisheries management

Institutional approaches in natural resource management in general and in fisheries in particular seldom address cultural aspects or social institutions like kinship. In this study, a broad institutional approach is used to investigate the institutionalization of small-scale fisheries and seaweed farming in a seagrass dominated bay in Zanzibar. Regulative, normative and cultural-cognitive institutions and their rapid/slow moving properties are analyzed. The results show that dynamics of cooperation and conflict between different institutional elements and the balance of forces among actors are crucial to understand fisheries management dynamics. Regulations are, despite their importance, insufficient to promote sound management if they are not backed up by norms and cultural-cognitive institutions. Fisheries management would benefit by broadening the institutional perspective to increase the efficiency of management and to avoid blueprint solutions. The study shows that gaining knowledge about the wide institutional setting takes time but the investment is worth it in the long run.