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Ecosystem and assimilative capacity of rivers with control structures
AuthorsE Imam ; S El Baradei
Date published2006
AbstractControl structures such as weirs and barrages constructed on a river will change the hydraulic regime of that river by increasing water depths and reducing velocities in the zones of developed backwater curves. The impact of water level control structures on the self-assimilative capacity of rivers is studied and possible changes in the ecosystem and fish habitat are assessed. A mathematical model is developed to simulate the river hydraulics water quality temperature and fish habitat. The diurnal dissolved oxygen concentrations are investigated to see their impact on the fish. A case study of a Nile River reach was examined to investigate the impact of the existence of the Esna barrage on the water quality in its upstream reach. To do this water quality indicators were developed to express the impact in a quantifiable manner. It is concluded that the barrage has negative impacts on the upstream self-assimilative capacity of the rivers that it has a positive effect on the fish habitat and that it causes a slight decrease in water temperature.
AuthorsE Imam ; S El Baradei
Date published2006
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Effect of Plate Width and Free Edges on the Initiation and Propagation of Fatigue Cracks in Plate-To-Plate Welded T-Joints
AuthorsC D Turner ; S B Lambert ; D J Burns
Date published2000
AbstractA probabilistic model for fatigue crack initiation and propagation in welded joints is used to determine the likely effect of plate (specimen) width and free edges on crack shape development and on fatigue life for T-plate joints with full penetration welds. This probabilistic model explicitly considers multiple crack initiation and coalescence. Its predictions of the influence of free edges on crack shape development including edge cracking are consistent with experimental observations.
AuthorsC D Turner ; S B Lambert ; D J Burns
Date published2000
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Effect of roller working on fatigue properties of eutectoid steel
AuthorsWenxian Sun ; Shin-ichi Nishida ; Nobusuke Hattori
Date published2002
AbstractAs one of the most important materials for industrial components eutectoid steel has been used in many industrial areas. In practical structure component the shapes of notches or steps are necessary and very useful according to the structural requirement. However the fatigue strengths of these components are significantly decreased because of the stress concentration at this position. Based on the statistical analysis more than 90% of failure of machine and mechanical parts are directly or indirectly caused by fatigue and nearly 90% of the fatigue cracks are initiated at stress-concentrated parts. Improvement of fatigue strength of these components is a serious challenge in engineering. Reports on the improvement of the fatigue strength of notched specimens are seldom observed. There are many methods to improve the fatigue properties through surface modification such as plasma technique surface chemical heat treatment etc. Among these methods roller working can be considered as an effective and low-cost method to improve the fatigue properties of bar shape components. A fatigue test is carried out to investigate the effect of roller working on notched specimen using eutectoid steel. Results are presented and and the reason for the improvement is also discussed.
AuthorsWenxian Sun ; Shin-ichi Nishida ; Nobusuke Hattori
Date published2002
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Energy savings and environmental benefits of stern flaps on navy ships
AuthorsDominic S Cusanelli ; Gabor Karafiath
Date published2006
AbstractThe application of stern flaps to large combatant-sized Naval vessels is a fairly recent innovation. A stern flap is an extension of the hull's bottom surface which extends aft of the transom. It is a relatively small and inexpensive addition which reduces the power required to propel a ship through the water. The US Navy has been investigating the powering improvements due to stern flaps on many different types of ships. The flap design and performance is optimised for speeds at which the ship expends the most power thereby maximising the potential for propulsion fuel reduction. The US Navy has installed prototype stern flaps on three ships and conducted ship trials to assess their effect on ship powering performance. The concept is presented and described. The design selection and analysis of the stern flaps are considered and their application to the three ships is described. The estimated fuel saving s and decrease in exhaust gas emissions for these applications are summarised.
AuthorsDominic S Cusanelli ; Gabor Karafiath
Date published2006
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Estimation Methods of Hydro-Elastic Responses on Very Large Floating Structure in Time Domain
AuthorsT Ikoma ; H Maeda ; C-K Rheem et al.
Date published1999
AbstractIn this paper an attempt is made to show the time domain analytical method of the deformation on VLFS in irregular waves and estimate the responses in time domain. As this analytical method is based on Fourier transformation and inverse Fourier transformation much calculation time can be saved. The corresponding experiment was carried out in a model basin. Some responses of elastic models were measured in uni-directional and two-directional irregular waves. It is confirmed that this is a very effective analytical method comparing with the time series of the experimental results. Also the linear superposition theory on the response analysis of VLFS was validated. Finally such time domain analytical method is expanded to 2nd-order response problem.
AuthorsT Ikoma ; H Maeda ; C-K Rheem et al.
Date published1999
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Evaluation of Strain Rate Effect on Fracture Behavior of Steel and Its Weldment
AuthorsK Arimochi ; N Konda ; M Toyosada et al.
Date published1998
AbstractIt is well known that the strain rate has notable effect on fracture behavior of steel and its weldment therefore it is important to require adequate toughness taking into account the effect of strain rate on the fracture behavior of structures for securing the safety of those structures subjected to dynamic loading such as offshore structures working in arctic region and buildings under the seismic conditions. In this paper an evaluation method of the strain rate effect based on the strain rate temperature parameter derived from the quasi dynamic fracture mechanics consideration is introduced first then the application results of the evaluation method for the clarification of fracture behavior of architectural beam-to-column connections under dynamic loading is described.
AuthorsK Arimochi ; N Konda ; M Toyosada et al.
Date published1998
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Influence of clay content and clay type on cyclic behaviour of compacted intermediate soils
AuthorsM A El Mesmary ; Y Nabeshima ; T Matsui
Date published2001
AbstractIn this paper a series of undrained cyclic triaxial loading tests was carried out on compacted intermediate soils to investigate the effect of soil properties on their cyclic behavior. The effect of clay content and clay type on the rate of build-up pore water pressure double amplitude (IDA) axial strain and degradation of stiffness during cyclic loading of the tested intermediate soils was studied. It was found that the increase of clay content in the soils increased the rates of build-up pore water pressure and DA axial strain and degree of stiffness degradation during cyclic loading. The clay type was an important parameter to control cyclic behaviour.
AuthorsM A El Mesmary ; Y Nabeshima ; T Matsui
Date published2001
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Influence of transient operating conditions on propeller shaft bearings
AuthorsGurr ; H Rulfs
PublisherIMarEST
AbstractRecent years have seen some severe sterntube bearing damages often following a sharp course change. This paper presents the development of a simulation model for oil lubricated journal bearings along with extensive measurements of the conditions in the aft sterntube bearing of a twin propeller Ro-Ro vessel. Results of these investigations demonstrate that hydrodynamic forces at the propeller during manoeuvring considerably influence the performance of the aft sterntube bearing. Depending on the character of the manoeuvre the journal gets tilted downwards to the aft end of the bearing or in a more horizontal direction towards the oil grooves respectively. The measurements confirm the suitability of the calculation program to simulate the bearing conditions. Therefore it is possible to evaluate the effect of design modifications on bearing performance and particularly on oil film thickness
AuthorsDate publishedGurr ; H Rulfs
2008
PublisherIMarEST
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Influent maximisation 'saturation' test on the OPB-10NP oil water-separator system
AuthorsMorales
Date published2006
AbstractTo comply with oil pollution abatement regulations OWSs (oil water separators) are being installed onboard all Navy surface ships. More stringent oil pollution regulations are anticipated. In anticipation of this CDNSWC carried out an influent maximisation test on the Navy's OPB-10NP OWS system to determine its maximum operational capabilities. The influent parameters that were varied are flow rate oil concentration and oil droplet size distribution - that is the basic design parameters of an OWS system which operates on the principle of gravity separation. During the test the effects of the various influent oil concentrations on the performance of the OPB-10NP OWS were determined. Different methods of analysing oil droplet size distributions in oily wastewater samples were also evaluated. The test set up is described and the method of evaluation is described. Test results are presented and discussed. Conclusions are drawn and recommendations are made.
AuthorsMorales
Date published2006
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Marine Accident Investigation Branch (MAIB) Report of the investigation into the loss of the fishing vessel Heather Bloom INS 110 with the loss of one life on 3 December 1994
AuthorsMAIB
PublisherDepartment of Transport (DOT)
AbstractOn 3 December 1994 the fishing vessel Heather Bloom with a crew of six snagged her fishing gear on an underwater obstruction causing her to heel heavily to port and to take on water. The vessel sank 60 miles north of Cape Wrath. Five of the crew were rescued. A significant contributory factor to her loss was the lack of a safe operational procedure for manually releasing the winch after hydraulic power was lost.
AuthorsDate publishedMAIB
1995
PublisherDepartment of Transport (DOT)
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Model test and analysis on oil skimmer at rough sea
AuthorsShirou Ono ; Hideyuki Omori ; Toru Iwasaki
Date published2002
AbstractIn 1998 the Association for Structural Improvement of the Shipbuilding Industry (ASIS) initiated a three-year research and development project on large-scale recovery systems for collecting highly viscous oil with a minimum kinematic viscosity of 100000 centi-stokes under severe sea conditions. This paper focuses on the design and evaluation of a newly developed oil skimmer system suitable for the recovery of highly viscous spilled oil emulsified under rough sea states. Furthermore synthesized model experiment was carried out in a water tank and oil basin using a large-scale model of a developed oil skimming system to acquire the performance data on the constituent technologies and to confirm synthetic function as an oil skimming and treatment system.
AuthorsShirou Ono ; Hideyuki Omori ; Toru Iwasaki
Date published2002
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Numerical simulation of ridge and sheet ice loads on a proposed faceted conical structure
AuthorsZ Wang ; A S J Swamidas ; D B Muggeridge et al.
PublisherAmerican Society of Mechanical Engineers - ASME
AbstractTwo series of numerical simulations based on the discrete element method were carried out to study the interaction of both multi-year sheet ice and multi-ridge ice with a proposed six-sided faceted conical structure. In the first series two physical tests were simulated one using sheet ice and the other using ridge ice with a small neck model of the faceted structure. The approach was verified by comparison of simulation results with those from tests. The ice failure process was analysed. In the second series of simulations a large neck structure was used. Comparison of the results showed the effect of neck size on both the sheet ice loads and the ridge ice loads exerted on the structure.
AuthorsDate publishedZ Wang ; A S J Swamidas ; D B Muggeridge et al.
1997
PublisherAmerican Society of Mechanical Engineers - ASME
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Optimising slot usage on a minimum facilities platform
AuthorsN S Avocato ; J R Jackson ; I G Jones et al.
Date published1995
AbstractChevron UK Ltd has increased the number of well slots on Alba Northern Platform (ANP) by over 20% at minimum cost. ANP is using four 46 inch OD caissons each housing two 20000 bpd wells. The close proximity well project (CPW) is a refinement of an application seen in some Gulf of Mexico and mud-slide areas whereby multiple wells are drilled from the same caisson. The CPWs will facilitate the drilling of 28 wells efficiently and economically from a platform originally equipped with 24 slots. Conductor sharing technology provides an additional 4 well slots on Alba Northern platform and the provision of these extra slots has helped remove the need for a second platform to develop the field which has had a major impact on project economics. The first CPW system was successfully installed during May and June 1995. The installation of two wells in the space reserved for one shows that it should be possible to design smaller lighter and cheaper platforms and so reduce a major item of capital expenditure.
AuthorsN S Avocato ; J R Jackson ; I G Jones et al.
Date published1995
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Photographic study on transient phenomena in pool boiling CHF for various liquids
AuthorsJongdoc Park ; Katsuya Fukuda ; Qiusheng Liu
Date published2005
AbstractEnergy conversion systems applied in the marine environment require higher performance and efficiency. It is very important to understand the mechanism and corresponding correlation of the boiling heat transfer for the effective use of existing energy conversion technology so we need to accumulate a fundamental database of CHFs (critical heat fluxes) on energy conversion. The purpose of this work is to clarify the transition phenomena to film boiling in several liquids having different wetability by the photographic approach on the vapour bubble and vapour film behaviour on the cylinder surface by using a high-speed video camera. Experimental apparatus and method are presented and results given and discussed and conclusions drawn.
AuthorsJongdoc Park ; Katsuya Fukuda ; Qiusheng Liu
Date published2005
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Potential influence of gas-induced erosion on seabed installations
AuthorsM Hovland ; O T Gudmestad
PublisherInternational Union of Geodesy and Geophysics (IUGG)
AbstractEvidence for the natural seepage / migration of gas and low density fluid through seabeds particularly in hydrocarbon rich regions of the world is presented with discussion of: seabed erosion features associated with the escape of gas / fluid notably "seabed pockmarks" and "mottled seafloor"; characteristics processes and mechanisms of migration and seepage; the effects on seabed installations both indirectly on soil properties and directly on structure behaviour; and methods (model and full-scale field trials) for the assessment of seepage processes prior to seabed construction pipeline gravity based and piled structures are considered. Particular attention is paid to areas of gas / fluid escape in the North Sea especially the densely pockmarked Norwegian Trench across which pipeline construction is intended.
AuthorsDate publishedM Hovland ; O T Gudmestad
1983
PublisherInternational Union of Geodesy and Geophysics (IUGG)
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Reduction effect of a submerged-plate toward wave exciting forces acting on a very large floating structure
AuthorsMikio Takaki ; Yasutaka Imai ; Sang-Min Lee
Date published2002
AbstractSub-Plate VLFS (a new type of VLFS using submerged plates) has been proposed for extending the operational area of VLFS to deeper sea with reducing environmental problems. The system consists of a FBSP (floating breakwater using submerged plate) and a VLFS with submerged plate. FBSP not only decreases incident wave height for VLFS but also generates a steady flow which enhances the exchange of seawater around VLFS; and is thus very friendly to sea environment. Here the focus is on the submerged plate built into the VLFS with the partial openings being 5 m long thus enabling the reverse flow on the plate. First extensive experiments are carried out to make clear the characteristics of the wave exciting forces and moments acting on the submerged plate and the fore part of VLFS.
AuthorsMikio Takaki ; Yasutaka Imai ; Sang-Min Lee
Date published2002
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Remote sensing of chemical pollutants on the ocean: a feasibility study
AuthorsMasahiko Sasano ; Kazuo Hitomi ; Hiroshi Yamanouchi et al.
Date published2005
AbstractNowadays huge amounts of petroleum chemicals are transported by ocean-going chemical tankers in particular aromatics - materials of various petroleum products. As these chemicals are low density than water and non-water solubility once a chemical spill has occurred it forms a massive chemical film on the ocean as well as petroleum oil. These chemicals are also toxic and shouldn't be touched or inhaled at high levels. The chemicals are limpid and hard to identify on the ocean with the naked eye even in good daytime light. Also the speed of volatilisation of these chemicals is higher than that of petroleum oil and the pollution is not only in the ocean but also extends to the atmosphere. All this means that these chemical pollutants are more difficult to treat than petroleum oil. Currently there is no practical application for monitoring chemical spill on the ocean.
AuthorsMasahiko Sasano ; Kazuo Hitomi ; Hiroshi Yamanouchi et al.
Date published2005
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Report of the Investigation into the fire on and sinking of the Passenger Vessel 'Sun Vista' on 20 and 21 May 1999 in the Malacca Straits
AuthorsBahamas Maritime Authority
Shelf Location226a
AbstractThe investigation into the fire and sinking of the Bahamian passenger ship Sun Vista was conducted by the Bahamas Maritime Authority as flag state of the vessel under the provisions of the Merchant Shipping Act. The Bahamas Maritime Authority investigates incidents at sea for the purpose of discovering any lessons which may be learned with a view to preventing any repetition. It is not the purpose of the investigation to establish liability or to apportion blame, except in so far as it emerges as part of the process of investigating that incident.
AuthorsPublisherBahamas Maritime Authority
Bahamas Maritime Authority
Shelf LocationDate published226a
2000
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Safe stowage and securing of cargo on board ships
AuthorsPhil Anderson ; B Allenstrom ; M Niiletsela
Shelf Location230d
AbstractDuring 1980 there were two severe accidents in the Swedish shipping industry, directly or indirectly caused by the shifting of cargo on board ships. This report is the result of research carried out concerning securing cargo at sea. It gives a survey and state conclusions of some accidents due to the shifting of cargo; the rules and recommendations concerning securing cargo on board ships; calculations of accelerations compared for different classification societies; full scale measurements of ship movements; an analysis of material properties in different types of securing equipment; conclusions regarding occurring loads and required safety factor; a survey of securing systems and equipment; calculations of lashing forces for some types of goods and covers securing of road trailers on board ro/ro ships.
AuthorsPublisherPhil Anderson ; B Allenstrom ; M Niiletsela
Swedish Shipbuilders Association
Shelf LocationDate published230d
1982
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Some considerations on dependability models of redundant power systems on board due to the marine field data in Japan
AuthorsT Hashimoto ; H Kido ; S Hidaka et al.
Date published2000
AbstractThis paper describes the models of redundant systems and dependability of power systems which are redundant engine sets with multi-cylinders for propulsive primemover and power generating station of ships and their running data and designing and manufacturing ones. Two kinds of surveyed data show the average number of generating sets per vessel is between 2.5 and 3.5. The JSRIC database is analysed during more than 7 million propelling hours and four kinds of evaluation indices are obtained. (Please note that the poor English used in this paper makes the content almost incomprehensible.)
AuthorsT Hashimoto ; H Kido ; S Hidaka et al.
Date published2000