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Nonlinear model of random wave load on pipelines
AuthorsZ Vukovic ; N Kuspilic ; C A Brebbia
PublisherWIT Press Computational Mechanics Publications
AbstractAn analytical procedure for predicting the wave load on submarine pipelines to the action of random waves representing the nonlinear drag force by cubic approximation is presented. The spectra of the horizontal and vertical component of wave force on pipelines are defined by the spectral analysis method using Morison's equation. Firstly assumptions are looked at. This is followed by a review of wave load analysis. Next the nonlinear model of random wave load on pipelines is looked at. Lastly a numerical example is given.
AuthorsDate publishedZ Vukovic ; N Kuspilic ; C A Brebbia
1998
PublisherWIT Press Computational Mechanics Publications
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Numerical modelling of snow-shedding effects on a 110 kV overhead power line in Slovenia
AuthorsJanez Jakse ; Mohamed Thabet Al Harash ; Ghyslaine McClure
Date published2001
AbstractThis paper presents a practical problem of reduced electrical clearances experienced in Slovenia on 110 kV overhead lines on double-circuit towers caused by the effects of heavy snow shedding. A numerical study of static and dynamic calculations has confirmed that deflected line configurations and large-amplitude oscillations resulting from load shedding are problematic. The situation was corrected by the utility on some line sections by installing phase-to-phase long insulating rod spacers similar to those used to mitigate galloping conductor oscillations.
AuthorsJanez Jakse ; Mohamed Thabet Al Harash ; Ghyslaine McClure
Date published2001
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On the behaviour of huge offshore structures in unprotected seas
AuthorsN Takarada
Date published1988
AbstractA summary of investigations into the technology assessment of huge offshore structures with special reference to the behaviour and stability of floating type airport structures is presented. Discussions are made first on the environmental conditions of the site and then the results of theoretical analyses and experimental studies are introduced on the motion of the floating model as well as on the feasible design of the mooring system for the structure.
AuthorsN Takarada
Date published1988
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Propagation of DC arc on ice surfaces
AuthorsJ Zhang ; M Farzaneh
PublisherInternational Society of Offshore and Polar Engineers
AbstractThe velocity of DC arc propagation on a triangular ice sample is described. Experiments were carried out in a temperature-controlled climate room using a thyristor- controlled DC system and a high-speed camera. It was found that the DC arcs may randomly propagate either inside or outside the ice sample in two stages - at a relatively low velocity and then at high speed when critical length is reached. The effects of voltage polarity on the propagation velocity of DC were studied. The mechanism of flashover arc on ice-covered insulators is discussed.
AuthorsDate publishedJ Zhang ; M Farzaneh
1998
PublisherInternational Society of Offshore and Polar Engineers
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Simulations of ice ridge forces on conical structures
AuthorsB Sand ; G Horrigmoe
Date published2001
AbstractThis paper is focused on nonlinear finite element simulations of multi-year ice ridge - structure interaction. A general finite element code (ANSYS Release 5.6) is used for numerical simulations. The ice is treated as an isotropic nonlinear material capable of cracking and crushing. An iterative procedure is used for automatic calculation of buoyancy forces on partially submerged ice features. In addition contact mechanics is applied for the precise tracking of contact and sliding between the ice ridge and the structure. Numerical results are compared with well established analytical procedures based on plastic limit analysis. The numerical results are in good agreement with analytical solutions obtained by plasticity theory.
AuthorsB Sand ; G Horrigmoe
Date published2001
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Spectral analysis of irregular wave impact on the structure in splash zone
AuthorsBing Ren ; Yongxue Wang
Date published2002
AbstractThe spectral analysis from experimental data of irregular wave impact on the structures with large dimension in the splash zone is presented. The experiments were conducted in the large wave-current tank in the State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology. The spectral analysis results of the irregular wave impact pressure on the subface of the structure under various case studies are presented. The distribution of spectral moment of the impact pressure on the structure along the subface is given.
AuthorsBing Ren ; Yongxue Wang
Date published2002
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Testing communications systems on diving installations
AuthorsV Flook
Date published1995
AbstractSafe practices efficient operations and effective response to an emergency depend on clear communications between diver and topside. Tests on commercial diving installations show that all parts of the system are important. The work which has been done on designing and testing helium unscramblers has resulted in several unscramblers which work well when tested under optimum conditions. Design of the complete system including microphones hard wiring and the acoustics of the space between the diver and the microphone needs to the addressed. The need for good pre-recorded tapes of helium speed remains.
AuthorsV Flook
Date published1995
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The impact of recent stability regulations on existing and new ships and the impact on the design of ro-ro passenger ships
AuthorsM Kanerva
PublisherElsevier
AbstractThe recent development of ro-ro passenger ferries is considered. Application of SOLAS 90 and the Stockholm Agreement is discussed for both newbuildings and existing ferries by describing typical two examples. Space below freeboard deck; centre or side casings; rational cargo handling; efficient arrangement for trailer ferry; damage stability; and upgrading existing ro-ro passenger ferries are all areas investigated.
AuthorsDate publishedM Kanerva
2000
PublisherElsevier
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The implications of an all electric ship approach on the configuration of a warship
AuthorsDavid Andrews ; Alistair Greig ; Richard Pawling
Date published2004
AbstractThis paper addresses the implication of the adoption of an All Electric machinery fit on the configuration of a modern warship. The paper presents a series of studies using the SURFCON graphically centred preliminary computer aided ship design tool based on the design Building Block approach which originated in the Ship Design Research team at UCL. Explorations are undertaken for a monohull frigate concept design on how an advanced electric machinery fit could be configured to provide a more effective and survivable overall ship design.
AuthorsDavid Andrews ; Alistair Greig ; Richard Pawling
Date published2004
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The influence of nickel and nitrogen on impact toughness properties of low alloy basic electrode steel deposits
AuthorsTomasz Wegrzyn
Date published2001
AbstractThe influence of the variable amounts of nickel and nitrogen on impact properties of different basic electrode deposits are tested. Furthermore on the basis of the results of the influence of the variable amounts of nitrogen and nickel on impact properties of low alloy basic electrode deposits mathematical equations regarding those relationships are assuming that oxygen content and acicular ferrite in basic electrode deposits are nearly constant and amount of each is respectively 350-450 ppm of oxygen and above 700 of acicular ferrite.
AuthorsTomasz Wegrzyn
Date published2001
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The ISPS Code as a component of onboard resources in Bayesian analysis
AuthorsV Loginovsky ; A Gorobtsov ; V Kuzmin
Shelf Location213c
AbstractThe already enormous regulatory workload on a ship's crew has been increased due to ISM Code requirements putting more stress on human and organisational factors and particularly on deck officers' attention and performance. Research to develop a model showing the impact of the ISPS Code on workload and crew performance is outlined. HUGIN is the Bayesian network tool used and shows overload on crew members and limited resources on onboard ship.
AuthorsPublisherV Loginovsky ; A Gorobtsov ; V Kuzmin
Southampton ; WIT Press
Shelf LocationDate published213c
2005
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Tidal effects on cross-shore sediment transport on a shingle beach
AuthorsL K Trim ; K She ; D J Pope
Date published2002
AbstractResults are presented from a laboratory model study of the sediment transport processes of a shingle beach under the combined action of waves and tides. Parallel experiments were conducted with a constant water depth corresponding to the high water level of the tidal experiments thus allowing a direct comparison between the two cases. A look is taken at the experimental procedure. This is followed by discussion of the results.
AuthorsL K Trim ; K She ; D J Pope
Date published2002
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Wastewater management on board - a burden or a necessity
AuthorsB Beler-Baykal ; M A Baykal ; A Kukner
Date published2000
AbstractShip-based pollution is the most significant source of marine pollution and accounts generally for around 20% of marine pollution. Factors affecting the pollution potential of sea-going vessels are considered. The impact of ship-based pollutants on the marine environment is examined. Wastewater management on board is discussed and it is concluded that it is environmentally friendly and essential (from the design stage and throughout a vessel's operational life) to prevent marine pollution and to maintain ecological balances in water.
AuthorsB Beler-Baykal ; M A Baykal ; A Kukner
Date published2000
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Wind tunnel investigation of the influence of propeller loading on ship rudder performance
AuthorsA F Molland ; S R Turnock
Date published1993
AbstractWind tunnel simulation experiments were used to study the interaction between a model propeller based on the Wageningen B-series and model rudders of different type (skeg fully movable) and taper/geometry. Model particulars are described together with details of the test rig data acquisition system and methodology. Results are presented as effect of propeller on rudder performance (load distributions and lift drag centre of pressure as functions of propeller thrust loading separation and geometry) and effect of rudder on propeller performance.
AuthorsA F Molland ; S R Turnock
Date published1993
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A feasibility study on a podded propulsion LNG tanker in Arun Indonesia -Osaka Japan route
AuthorsJaswar Kim ; Yoshiho Ikeda
Date published2002
AbstractAn economical-environmental model for the evaluation of a marine transportation system is proposed. In the model a transportation system is evaluated based on an economical-environmental index. The index is determined by dividing an economical impact by an environmental impact. The economical impact is calculated by multiplying an economical ratio by a weight of economical impact. The environmental impact is calculated by summing up the multiplication of each element of environmental ratio by weight of each element of environmental impact respectively. The economical ratio consists of economic margin and return ratios and business impact. The environmental ratio includes annual volumes of CO2 NOx and SOx emitted per annual cargo capacity. These economical and environmental ratios are determined using technical data including cargo capacity engine power and building cost of a ship. The weights of economical and environmental impacts depend on public opinion. These weights are determined by using the AHP (analytical hierarchy process) model on the basis on public opinion. Using the model a feasibility study on a podded propulsion LNG (liquefied natural gas) tanker is accomplished by comparing it with a conventional one which has been operating for some 20 years.
AuthorsJaswar Kim ; Yoshiho Ikeda
Date published2002
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Comparative assessment of design based on revised API bulletin 2U and other recommendations
AuthorsCuneyt C Capanoglu ; Stephen W Balint
Date published2002
AbstractAPI Bulletin 2U is the bulletin on Stability Design of Cylindrical Shells. It has provided guidance for the design and analysis of cylindrical shells since its first publication in 1987. The API Bulletin has recently been revised and the second and third editions issued. A brief summary is presented of the changes introduced into the third edition of Bulletin 2U. Firstly it analyses several TLP column designs based on the second edition of Bulletin 2U. Secondly the designs are reviewed based on the third edition of API Bulletin 2U and modified as necessary. Thirdly the designs are further modified to meet the requirements of Det Norske Veritas. The discussion and tables and figures illustrate the sensitivity of various parameters on design and indicate the significance of the design basis on design and product. The buckling stress equations are briefly discussed and a comparative assessment of buckling stresses applicable to different orthotropically stiffened cylindrical shells. The paper then presents several large diameter cylindrical shell designs applicable to TLP columns. These columns are reanalysed using both API Bulletin 2U and DNV recommended design equations to show that in the third edition of Bulletin 2U the designer has the flexibility and information needed to design cylindrical shells that have structural integrity and yet remain cost effective.
AuthorsCuneyt C Capanoglu ; Stephen W Balint
Date published2002
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Low overlap image registration based on both entropy and mutual information measures
AuthorsCedric de Cesare ; Maria-Joao Rendas ; Anne-Gaelle Allais et al.
Shelf Location214b
AbstractEstablishing a visual map of a region observed by an onboard camera of a mobile robot is a powerful tool which can be used either for post-mission environment analysis or for on-line navigation. A new approach to image matching based on both entropy and mutual information measures that can correctly carry out association under very low overlap conditions is presented. The method is feature-based working on a list of interest points detected on the acquired images. Unlike the classical SSD-RanSaC method this algorithm is robust to the existence of many similar regions in the images thus enabling situations to be handled where the interest points correspond to local details of a habitat that is dispersed with a regular-like structure across the ocean bottom. This method actually only requires that four corresponding points be detected in the two images being aligned. This allows matching under minimal overlap of the images. The improvement in efficiency of this method when compared to previous techniques relies on explicitly accounting for ambiguities in the association between the templates of the two images thus preventing that useful information be discarded at an early association step.
AuthorsDate publishedCedric de Cesare ; Maria-Joao Rendas ; Anne-Gaelle Allais et al.
2008
Shelf Location214b
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Statistical modelling of overtopping on a fixed deck
AuthorsNobuhito Mori ; Daniel T Cox
Date published2002
AbstractMany offshore platforms have suffered from significant wave loading on their lower deck and FPSOs (floating production storage and offloading) systems have also suffered topside damage from 'green water' on their decks during storms. However understanding of the wave kinematics such as crest velocities accelerations and overtopping rates for extreme events remains rudimentary. Although the overtopping of shallow water coastal structures has been well studied there have been very few studies on overtopping of a fixed deck in deep water with high wave steepness (i.e. storm conditions). A statistical model is developed to predict wave overtopping of extreme waves on a fixed deck. Here existing theories developed for crest statistics to the problem of wave overtopping are extended; the theoretical model is compared with experimentally determined overtopping probability distributions. Firstly the statistical formulation of the problem is presented and the sensitivity of the derived probability functions to non-linearity and deck clearance is shown. The experimental setup and procedures of the small-scale hydraulic model test are presented. Conditional sampling of the crest heights seaward of the deck produced a normalised probability distribution similar to that of the maximum water level measured on the deck for each over-topping event. A detailed discussion of the model-data comparisons is presented. It is concluded that the model prediction of the exceedance probability of deck overtopping has given very good agreement for large over-topping values.
AuthorsNobuhito Mori ; Daniel T Cox
Date published2002
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Conf on - Effect on ship design and operation of the 1978 IMCO Tanker Safety and Pollution Prevention Conference 7 Dec 1978
PublisherIMarE Conferences and Symposia
Date published1978
PublisherIMarE Conferences and Symposia
Date published1978
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Log of the Centurion:Based on the Original Papers of Captain Philip Saumarez on Board HMS Centurion, Lord Anson's Flagship During his Circumnavigation, 1740-44
AuthorsLeo Heaps
Shelf Location36d
AuthorsPublisherLeo Heaps
London, Hart-Davis, MacGibbon [1973]
ISBN number24610581
Shelf LocationDate published36d
1973