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During offshore drilling operations marine risers carry mud and debris from below the sea floor and during production operations they are responsible for transporting oil or gas from the hydrocarbon reservoir to the surface platform. The integrity of a marine riser is therefore critical to the success of offshore drilling and production. The flow of seawater around marine risers is subject to vortex shedding which excites oscillations known as VIV (vortex-induced vibrations). When the VIV frequency approaches one of the natural frequencies of the structure resonance or lock-in occurs. This results in enhancement of the vibration amplitude of the structure and may have potentially destructive consequences due to high bending stresses and fatigue damage of the riser. At present the production of this phenomenon is one of the most challenging areas in the offshore industry. In experimental investigations of VIV large-aspect ratio risers - that is long cylinders with relatively small diameters pose a modelling challenge. This paper focuses on the development field-testing and data analysis of a large-scale model riser capable of transmitting data in real-time under realistic operating conditions. The large-scale riser was mounted to the port side of a small vessel and towed off the east coast of Newfoundland through a series of vessel velocities corresponding to realistic operating conditions for deep-water risers. Results are presented. Also included is an analysis of the modal vibrations experienced by the riser as well as the in-line and cross-stream motions over a series of vessel speX35409

Diesel TES Engine Oil has a high-energy efficiency and can therefore help to reduce carbon dioxide emissions and so it is expected that this will be widely adopted. However several issues remain including the bother of engine oil maintenance. The purpose of this research was therefore to lengthen the maintenance interval of the engine oil to 16000 hours. To achieve this longer maintenance interval a special oil was developed that has a synthetic base stock. Simulations of the oil's degradation were carried out and it was succeeded in preventing degradation by developing a system for extracting degraded oil and adding new oil. It was also made possible to monitor degradation of engine oil by installing a soot sensor to measure the concentration of soot which is the factor that has the largest effect on the degradation of diesel engine oil. In addition an electrostatic dust collector was installed to avoid problems caused by soot contamination. This collector worked well when the oil deteriorated. The verification tests of this system showed that the oil's properties stopped changing completely after 1500 hours of operation and operation is now continuing smoothly at the 8000-hour point. However even if the oil maintains its high performance tests of small engines have confirmed that the conditions of the pistons change over time. While engine oil maintenance can be avoided the engine itself must continue to be maintained at regular intervals.

Daring the Royal Navy's new Type 45 Destroyer first went to sea in July 2007 and is due to enter service in February 2010. She uses an HV (high voltage) (4.16 kV) IEP (integrated electric propulsion) system with LV (440 V) supplies derived directly from the HV bus bar via transformers. The LV distribution system is therefore subject to the transients seen on the propulsion bus bar. This paper looks at the methods used to capture and analyse quality of power supplies data onboard. The results show that the requirement for Def Stan 61-5 - Stanag 1008 supplies is met although the envelope of allowable excursions is fully explored. The expertise built up over a number of sea trials has enabled problems to be rapidly identified and resolved. The causes of some unusual and unexpected excursions are explored. The response of the system to LV short circuit faults was also captured and is reported in this paper. As might be expected a number of equipments have failed during setting to work with assertions that QPS (quality of power supply) excursions are the root cause. A sample of the resultant studies is presented to illustrate the value of the QPS capture methods used in resolving issues speedily and economically. From the experience of Type 45 design and operation proposals are made to reduce the cost of procurement through management of QPS requirements.

The Joint Wildlife Countryside and Environment Links (Joint Links) believe that the UK urgently needs a strategic plan-led approach in the marine environment to help avoid or reduce conflict to identify and permit appropriate and compatible developments and to protect and enhance important environmental and social assets from inappropriate development. Marine spatial planning is fundamental to deliver the Government's vision as detailed in the Marine Stewardship Report. The merits of such an approach are identified and it is explored how such a system might operate in practice. This follows a number of government commitments and initiatives. As development and activity increases in the marine environment the sectoral approach is no longer an option. It is thought that a plan-led system is now essential. This plan-led system is presented. It is believed that a strategic marine spatial planning based on natural ecosystem boundaries is essential to begin to halt the decline in marine biodiversity to protect underwater cultural heritage and to promote and plan for sustainable development and use in the marine environment. It is considered why the UK needs a strategic marine planning system. This is followed by consideration of policy what a marine spatial plan (or strategy) might look like and who would develop such a plan. The core principles aims and objectives are outlined. The Joint Links are therefore calling upon the Government to promote and develop a system of strategic Marine Spatial Planning as a product of the current DfT review.

A 3D numerical model ASL-COCIRM is applied to examine the impact of the Burrard Generating Station cooling water on the circulation patterns and thermal regime in the receiving water of Port Moody Arm. A key aspect involves properly incorporating the submerged cooling water buoyant jet into the 3D model. To overcome the scale and interface barriers between the near-field and far-field zones of the buoyant jet a sub-grid scheme is applied and the coupled system of equations of motion heat conservation and state are solved with a single modelling procedure over the complete field. Special care is taken with the diffusion and jet entrainment by using a second order turbulence closure model for vertical diffusion and the Smagorinsky formula for horizontal diffusion as well as jet entrainment. The model is calibrated and validated in terms of buoyant jet trajectory centreline dilution and temperature and velocity profiles. Extensive modelling experiments with and without the Burrard Generating Station in operation are carried out to investigate the receiving water circulations and thermal processes under the influence of the cooling water discharge. The model results reveal that under the influence of the cooling water discharge peak ebb currents are stronger than peak flood currents in the near-surface layer and the reverse is true in the near-bottom layer. Meanwhile the model reveals a well-developed eddy at the southeast side of the buoyant jet in the near-surface layer. It is also found that the warmer water released from the cooling water discharge is mainly confined to the upper layer of the Arm whX38886

Tides and large-scale disturbances to the ocean waters during cyclone storm surge and tsunamis could be classified under long waves governed by SWE (shallow water equations). Appropriate modelling of such shallow water processes for real ocean have to be carried out numerically since the ocean has irregular boundaries and the equations under consideration are non-linear. As the scale of disasters due to such phenomena is massive the modelling gains centre stage for the purpose of forecasting the level of the disasters and the mitigation measures. The SWE being compact and simpler is an effective mathematical tool in the modeling of tsunamis on the global earth. This can also model tsunami travel times and landfall amplitudes close to the observed data. However the irregular boundaries of the coastlines of the global ocean can better be represented using unstructured grid and more accurate solution can be achieved than the structured grid. SWE are solved using an UEFEM (unstructured explicit finite element method) to simulate long waves in the ocean. The formulation of the UEFEM has been described and found to be computationally efficient for large problems such as basin level modeling of tsunamis. Different domains have been considered to simulate the propagation of the waves due to an artificially imposed initial disturbance. The domain of Bay of Bengal has been considered for simulation with an initial disturbance which resembles the type and location of the 2004 Indian Ocean Tsunami. The Wave elevation and deformations as well as time of travel of tsunami are reproduced. The method hence has high potential of being attractive forX37823 Modelling of the sediment transport at the Belgian coast

The problem of ship motions and ship stability is of fundamental concern to naval architects during the design process. Although conventional techniques and regulations have been reasonably successful in assuring a satisfactory level of stability for large vessel types the number of ship losses especially the medium and small-sized ones require new methods of analysis. Motions and capsizing of a B.C. West Coast fishing boat in following and beam seas were experimentally investigated. A computer controlled wave maker generated regular sinusoidal and breaking waves of different variable frequencies and amplitudes along a 220-foot model basin. The model was self-propelled radio-controlled and equipped with an on-board data acquisition system. Pitch roll yaw surge heave sway and rudder angle values and wave amplitude were measured. Different load conditions and GM values ranging from 1 to 10 per cent of the beam value were studied. In following seas it was found that a portion of the wave system with wavelengths equal to or longer than the model length would cause severe motions or instability. Zones of dynamic instability associated with wave frequency and amplitude were obtained. In beam seas the model remained stable in all sinusoidal and breaking waves generated by the wave maker. The experiments showed the fishing boat stability in following seas poses more problems than does the stability in beam seas. A method to extend the stability in sinusoidal waves to a specific wave spectrum is considered.

Traditionally the AUV (autonomous underwater vehicle) design process has largely been 'ad hoc' with designs governed by experience and rules of thumb. Multi-disciplinary design optimisation has been increasingly used in conceptual design problems in many fields where a system level approach at the conceptual design stage can yield significant design improvements. Here a design optimisation process for an AUV is developed using a MOGO (multiple objective genetic optimisation) algorithm. The optimisation is implemented in MC (ModelCenter) from Phoenix Integration. It uses a genetic algorithm that searches the design space for optimal feasible designs by considering three MOPs (measures of performance): cost effectiveness and risk. The synthesis model is comprised of an input module three primary AUV synthesis modules a constraint module and three objective modules. The effectiveness determined by the synthesis model is based on nine attributes identified in the UDS Navy's UUV Master Plan and four performance-based attributes calculated by the synthesis model. To solve multi-attribute decision problems the AHP (analytical hierarchy process) is used. Once the MOGO has generated a final generation of optimal feasible designs the decision-maker(s) can choose candidate designs for further analysis. A sample AUV synthesis was carried out and five candidate AUVs were analysed. Conclusions are drawn.

The compressibility of fuel and the effects of pressure wave dynamics govern the injection in a CRS (common rail system). The layout of the system volume and its geometrical distribution within the system strongly affect the injection events at every injector. Here new technological solutions are presented which eliminate the above-mentioned shortcomings of CRS in the off-road engine power domain between 1 and 5 MW. Based on simulation results achieved when modelling the CRS with the hydraulics simulation tool AMESim new common rail injectors and high-pressure pumps were designed built and tested. These represent the key to novel systems which are best suited to Diesel Engines with an overall power output of 1 to 5 MW such as those used in locomotives ships power generation and heavy earthmoving machinery. The injectors have an accumulator chamber within an injector body which easily fits into the engine's cylinder head. The actuating components are all in the front part leading to a compact design. The injection rates of the injector show its good performance with or without multiple injections. The injection law is compared to that of a former system equipped with rails and without an accumulator in the injector.

At a time when there is an increasing demand for lowering diesel engines' exhaust gas emissions the fuel injection system is a key technology. The improvement in emission laws has revealed that a flexible fuel injection system (especially with product features like injection rate shaping free adjustment of injection pressure flexible start of injection pre- and post injection) can safely fulfill these customer requirements. An environmentally friendly combustion is also important for medium-speed engines in marine and stationary applications. Therefore HFO (heavy fuel) engines will need CR (common rail) injection systems with a high degree of flexibility that will dominate the market in the future. For many decades MAN B&W has been developing and producing fuel injection systems for its medium-speed diesel engines. It was only natural to develop the HFO CR technology. The MAN B&W CR concept was incorporated in a long-term technology planning. Besides the emission requirements important safety aspects for marine application were integrated. After the first basic investigations a modular system of components for a HFO CR fuel injection system was developed depending on engine type and size. The novel concept for HFO application finally comprised a single circuit system without additional servo-control circuit and with modular rail segments. By matching the control valve

Conf held in London Dec 12 - 13 1972 Papers are The oil potential of the North Sea Servicing and supplying rigs and platforms The significance of the North Sea in the context of the world oil reserves The prospects for North Sea natural gas Oil and gas technology offshore of the United Kingdom British government policy towards the North Sea A Middle Eastern view of the North Sea developments The financing of North Sea exploration and exploitation - an American view The fabrication and installation of offshore drilling and production platforms EEC energy policy and the North Sea Some investment implications of North Sea oil and gas - a Scottish view The North Sea within the frame work of world oil policies and economics The British Steel Corporation and the North Seabed equipment in the context of North Sea oil and gas The operation of oil rigs The role of the City in financing North Sea development Hydrocarbon potential of offshore western Britain and Ireland A summing up of the first North Sea conference Report on the 1972 drilling season Norway and the North Sea British industry and North Sea oil Scottish investment in the North Sea North Sea potential - the view of the Gas Council The Norwegian industry view of North Sea oil and gas A socialist view of North Sea developments

Local scour around an offshore pipeline has been extensively investigated both experimentally and numerically in the past decades. So far most of the studies on scour below pipeline are concerned with a single pipeline. Offshore pipelines of different diameters are sometimes laid together as a bundle due to technical or economical considerations. A pipeline bundle comprises a large pipe and a few small pipes. The pipelines in a bundle can either be in direct contact with each other or can be separated by small gaps. The most popular configuration of pipeline bundles comprises one large pipeline with a smaller one installed directly above it. This is often referred to as the piggyback pipeline. Local scour under two pipelines of different diameters in steady currents is investigated numerically. The two pipelines are arranged in the piggyback configuration. The RANS (Reynolds-averaged Navier-Stokes) equations and the transport equation of the suspended sediment concentration are solved using a finite element method. The sediment mass conservation equation is solved for predicting the bed scour profile. The numerical model is firstly validated against the scour below a single pipeline where the experimental data are available. Then the model is used to simulate the scour below two pipelines in steady currents. Computations are carried out for the diameter ratio (the small pipe diameter (d) to the larger one (D)) of 0.2 and the gap (G between the two pipelines) to the large diameter ratio G-D ranging from 0.0 to 0.5. It is found that the flow and the scour profiles are influenced significantly by the gap ratio94029 Numerical modelling of nitrogen cycling in Suo-Nada Japan Mitsuru Hayashi ; Tetsuo Yanagi

The description of extreme surface water waves in deep water is considered. Extreme waves in the ocean are known to have three underlying physical characteristics: they are highly nonlinear often at or near their breaking limit; they are unsteady with energy distributed across a wide frequency range; they are short-crested with energy travelling in many directions. Recent Fourier-based numerical models have shown that if a modelling procedure is to be effective each of these properties needs to be included. Unfortunately Fourier-based models are limited in the sense that they cannot be applied to waves that are at the very limit of wave breaking and-or have begun to overturn. One technique which is not limited in this way is BEM (the boundary element method). However although there have been some preliminary attempts to model wave focusing no BEM-based model has been capable of modelling realistic wave fields. A study is presented which addresses this issue presenting a fully non-linear 3D wave model based on the BEM which is then applied to wave focusing. The model uses multiple fluxes at domain corners and edges in order to overcome the 'corner problem' associated with the BEM technique and is shown to be capable of modelling realistic

A buoy design has been developed which satisfies the requirements of a multi-purpose vessel for unmanned or manned conditions. When moored the buoy design constitutes a stationary vessel which is not affected by confused seas due to its axial symmetry. The overall design has focused on fabrication efficiency ultimate stability and safety. The buoy is characterised by a very high ratio of buoyancy to fabricated weight. The design is presented. One advantage of the design is that the vessel can be fitted with thousands of tons of deck equipment dockside and then towed to its offshore location. This avoids the need for offshore vessels to lift equipment and avoids the need for offshore MPT vessels to install equipment or well control systems. In addition hook-up and commissioning can be done prior to installing the buoy offshore. The basic design has undergone tank testing and has been shown to be suitable for a variety of offshore applications including deep water high current environments and hurricanes. Design features that have been studied and resolved include the hydrodynamics mooring options scantling design raising and lowering systems for the center column and self-tensioning systems for pre-installed mooring. The floating buoy is seen as an alternative to the use of FPSOs SPARs TLPs etc for deepwater gas and oil production. Other applications are also identified.

Subsea pipelines have the tendency to buckling globally due to the expansion force caused by high temperature and high pressure. The resulting large vertical or horizontal deformations may cause structural failure of the whole pipeline system. In the case of pipelines being exposed on an undulating seabed the pipelines have a tendency to undergo global buckling by first lifting off the seabed and then suddenly buckling horizontally when the effective compressive force reaches a critical value. With the offshore development moving to a more hostile environment thermal buckling has become an important issue and it is necessary to considered it for HPHT (high-pressure high temperature) subsea pipelines design. In order to control the lateral buckling the snaked lay method is investigated theoretically and numerically. The buckling mechanisms of the curved beam are studied with methods considering the finite strain and simplified straight beam theory respectively. The differences between the two methods are found to be negligible when the radius of curve is larger than a certain value. Detailed FE analysis results are given for the buckle behaviour of a snaked-lay pipeline. The method to control the subsea pipeline lateral buckling is discussed and followed by a design example.

Reciprocating engines fuelled by natural gas or alternative gases are increasingly used to distribute generated electricity often in combination with cogeneration. At the same time a high availability of electricity is very important in modern life and for many production processes. With a proper design gas-fuelled engines have a suitable response to load steps so that they can serve as emergency power supply in case the electricity grid fails. This greatly improves the economic value of the financial investment. Gas engines equipped with per-cylinder fuel injection via electromagnetic gas admission valves are able to instantaneously control the air-to-fuel ratio of the mixture. If such engines are normally running on a lean mixture for which pre-chambers or diesel pilots are required for ignition temporary enrichment of the mixture can be accomplished. A pre-requisite is that the gas admission valves have a sufficient range in their opening time. Enriching the mixture results in a higher energy content of the cylinder charge which helps to rapidly create the required torque during a positive load change. At a stepwise load reduction the gas admission can be drastically reduced so that the speed overshoot is minimised. If no throttle valve is used no risk of surge of the compressor of the turbocharger will occur during a downward load step. As a result the engine speed and the generator voltage can be kept within close limits. The reaction of the cylinder process during a step load is illustrated. It is explained how the initial speed change durinX21927

Technology has transformed the San Francisco Bay region. Silicon Valley and the biotech industry produced plenty of high-paying positions that inflated the economy and created traffic congestion of immense proportions. Growth projections show 1.2 million new Bay Area jobs and a 1.4 million population-increase during the next 25 years accompanied by a 30 per cent increase in region-wide travel and a 40 per cent increase in trans-bay travel. In an effort to counter the negative aspects of an immobile and consequently less productive commuter society the California State Legislature created the San Francisco Bay Area WTA (Water Transit Authority) with a mandate to improve public transit with an environmentally friendly ferry system. The WTA's mission is to build and operate a cost-effective convenient and environmentally responsible ferry system that will enhance commuter choices and the Bay Area's public-transit system. Various environmental implications of ferries are discussed including ferry impacts on the water bird populations marine mammals plants and people; shoreline response to wake impacts; emissions; safety; security; and aesthetics.

The development of a new family of PE materials with significantly improved processability and long-term strength at high temperatures is discussed. These polymers form the basis for a new ISO class of polyethylene materials: PE-RT (Polyethylene of raised temperature resistance) for hot and cold water as well as industrial pipe applications. These materials have a unique molecular structure and crystalline microstructure which provides excellent long-term hydrostatic strength at high temperatures without cross-linking the material. PE-RT type materials are already successfully used in domestic hot and cold water piping systems for most applications. The easy processing and outstanding material properties also made these resins attractive for use in many industrial applications where larger dimensions are required and regular Polyethylene cannot be used or has temperature limitations. These resins also compete against high-end engineering plastics offering significant cost savings. These materials provide significant process advantages to the converters allowing high line speed pipe production and providing excellent flexibility and ease of installation for the application. A recently developed PE-RT type material offers still higher long-term strength at high temperature and further improved processability. This combination makes this resin particularly suitable for high temperature applications. An example of the latter is in larger-diameter cooling water pipes in power plants. Pipes based on these materials can be connected with heat welding or by mechanical fittings. Furthermore this material can be used in industrial applications were tControl No Title

Important issues relating to the planning and implementation of coastal zone management in Sri Lanka are highlighted. The need has been identified for coastal zone management to be introduced as well as its different stages of development and implementation. The priority activities undertaken by the Coast Conservation Department with respect to identifying the extent of erosion the construction of coast protection works and overall coastal zone management planning are outlined. Attention is also focussed on the management of development activities in the context of regulation administration and monitoring. Recent developments in coastal zone management are also summarised. There is a need to adopt a well-coordinated strategic approach in the management of sustainable multiple uses of the coastal zone. This objective could be achieved by developing an integrated coastal management framework for the environmental protection of the coastal zone. A review of previous studies related to coastal zone management in Sri Lanka shows that results of these studies could be used very effectively to provide a sound foundation for the development of an integrated coastal management framework. The development of such a framework would greatly assist in the overall management of coastal zone activities strategic planning for coastal regions assessment of regulation needs and the decision-making process regarding the transfer of functions to local and provincial authorities.

One of the advantages of parametric array is the convenience of being able to generate low-frequency wideband signals in different frequency components. Several kinds of signals usually used in linear active sonar generated by non-linear self-demodulation of primary waves are studied. Emphasis is on the pre-processing methods and the spectrum characteristics before and after the self-demodulation process related to these methods. Analyses and simulations show that the inverse processing which includes a double integration and a square-root operation is with no practical value because the integration shifts most of the signal power to the very low frequency components and the useful signal generated from the non-linear acoustic interaction whose frequencies are relatively much higher is very weak. In order to generate the LFM signal in the secondary acoustic field of parametric array an LFM waveform divided by its instantaneous frequency to be the envelope of primary wave can be used. In order to generate digital modulated signals from the self-demodulation process PAM signals with M=2 and zero as one of the two symbols perform much better than BPSK signals. CFPSK signals are also suitable for digital signal transmission through the non-linear self-demodulation process of parametric array. Simulation also shows that Ricker wavelet can be generated by simply using half-cosine wave passing through a low pass filter as the envelope of primary wave.