A framework for reliability assessment of ship hull damage under ship bow impact

Peer reviewed

A framework for reliability assessment of ship hull damage under ship bow impact

Peer reviewed

A framework for reliability assessment of ship hull damage under ship bow impact

Peer reviewed

Annotated record of the detailed examination of Mn deposits from various ship expeditions in the Atlantic Ocean from 1876 until 1911

The greater part of this Monograph is devoted to detailed descriptions of 1426 samples of deposits from the floor of the Atlantic Ocean stored in the Challenger Office, Edinburgh, which had been collected during thirty-five cruising expeditions between 1857 and 1911. The remaining part discusses the results of the work. The work of examining and describing in detail this abundant mass of material was in progress when the late Sir JOHN MURRAY met his death in March 1914. By that time about three-fourths of the descriptive work had been completed under his supervision. Sir John's trustees arranged for the completion of the descriptive work by Mr Chumley, and this was done in the Challenger Office during the two succeeding years. Later, after he had removed to Glasgow, Mr Chumley prepared the notes discussing the results. The trustees have pleasure in recording, on the suggestion of Mr Chumley, the courtesy of Dr G. W. Lee of the Geological Survey of Scotland, for help in determining many of the rarer mineral particles contained in the deposits.

(Table 3, page 309) Mercury content of concretions from Grand Lake (GL) and Ship Harbour Lake (SH), Nova Scotia and Mosque Lake (ML), Ontario

Ferromanganese concretions from Grand Lake and Ship Harbour Lake in Nova Scotia and Mosque Lake in Ontario are most common in water 0.5 to 2 m deep. X-ray diffraction studies show the ferromanganese portions of the concretions to he amorphous. Petrographic and electron probe studies of the ferromanganese material reveal chemical banding of iron and manganese. Bulk chemical analyses indicate that the Fe:Mn ratios of concretions from different sites within a single lake are similar, whereas concretions from different lakes have characteristic Fe:Mn ratios. Trace element concs are different in different lakes and are generally several orders of magnitude less than those of oceanic nodules.

Annotated record of the detailed examination of Mn deposits from Hudson-70, Phase VII cruise (CNAV Endeavour) stations

A geophysical survey was conducted off Vancouver and Queen Charlotte Islands over a four-week period (July 12 to August 5, 1970) as part of HUDSON-70 expedition. The HUDSON-70 expedition was organized as part of the Canadian contribution to the International Decade of Oceanographic Exploration. The geophysical survey was conducted to study the subsurface structure across the continental margin off the British Columbia coast and in the deep ocean basins. The present report contains descriptions of the various measurements made during this cruise and the data collected.

Temporal and spatial variation in temperature experienced by macrofauna at main endeavour Hydrothermal vent field

A significant focus of hydrothermal vent ecological studies has been to understand how species cope with various stressors through physiological tolerance and biochemical resistance. Yet, the environmental conditions experienced by vent species have not been well characterized. This objective requires continuous observations over time intervals that can capture environmental variability at scales that are relevant to animals. We used autonomous temperature logger arrays (four roughly parallel linear arrays of 12 loggers spaced every 10–12 cm) to study spatial and temporal variations in the thermal regime experienced by hydrothermal vent macrofauna at a diffuse flow vent. Hourly temperatures were recorded over eight months from 2010 to 2011 at Grotto vent in the Main Endeavour vent field on the Juan de Fuca Ridge, a focus area of the Ocean Networks Canada cabled observatory. The conspicuous animal assemblages in video footage contained Ridgeia piscesae tubeworms, gastropods (primarily Lepetodrilus fucensis), and polychaetes (polynoid scaleworms and the palm worm Paralvinella palmiformis). Two dimensional spatial gradients in temperature were generally stable over the deployment period. The average temperature recorded by all arrays, and in some individual loggers, revealed distinctive fluctuations in temperature that often corresponded with the tidal cycle. We postulate that this may be related to changes in bottom currents or fluctuations in vent discharge. A marked transient temperature increase lasting over a period of days was observed in April 2011. While the distributions and behavior of Juan de Fuca Ridge vent invertebrates may be partially constrained by environmental temperature and temperature tolerance, except for the one transient high-temperature event, observed fluid temperatures were generally similar to the thermal preferences for some species, and typically well below lethal temperatures for all species. Average temperatures of the four arrays ranged from 4.1 to 11.0 °C during the deployment, indicating that on an hourly timescale the temperature conditions in this tubeworm community were fairly moderate and stable. The generality of these findings and behavioural responses of vent organisms to predictable rhythmicity and non-periodic temperature shifts are areas for further investigation

Hamburg model basin : numerical and experimental investigations on the dependence of the fluctuations of thrust and torque on the blade area ratio of four-blade ship-propellers /

Contract no. N 62558-2223.

Air Entrainment in the Turbulent Ship Hull Boundary Layer

Turbulent fluctuations in the vicinity of the water free surface along a flat, vertically oriented surface-piercing plate are studied experimentally using a laboratory-scale experiment. In this experiment, a meter-wide stainless steel belt travels horizontally in a loop around two rollers with vertically oriented axes, which are separated by 7.5 meters. This belt device is mounted inside a large water tank with the water level set just below the top edge of the belt. The belt, rollers, and supporting frame are contained within a sheet metal box to keep the device dry except for one 6-meter-long straight test section between rollers. The belt is launched from rest with an acceleration of up to 3-g in order to quickly reach steady state velocity. This creates a temporally evolving boundary layer analogous to the spatially evolving boundary layer created along a flat-sided ship moving at the same velocity, with a length equivalent to the length of belt that has passed the measurement region since the belt motion began. Surface profile measurements in planes normal to the belt surface are conducted using cinematic Laser Induced Fluorescence and quantitative surface profiles are extracted at each instant in time. Using these measurements, free surface fluctuations are examined and the propagation behavior of these free surface ripples is studied. It is found that free surface fluctuations are generated in a region close to the belt surface, where sub-surface velocity fluctuations influence the behavior of these free surface features. These rapidly-changing surface features close to the belt appear to lead to the generation of freely-propagating waves far from the belt, outside the influence of the boundary layer. Sub-surface PIV measurements are performed in order to study the modification of the boundary layer flow field due to the effects of the water free surface. Cinematic planar PIV measurements are performed in horizontal planes parallel to the free surface by imaging the flow from underneath the tank, providing streamwise and wall-normal velocity fields. Additional planar PIV experiments are performed in vertical planes parallel to the belt surface in order to study the bahvior of streamwise and vertical velocity fields. It is found that the boundary layer grows rapidly near the free surface, leading to an overall thicker boundary layer close to the surface. This rapid boundary layer growth appears to be linked to a process of free surface bursting, the sudden onset of free surface fluctuations. Cinematic white light movies are recorded from beneath the water surface in order to determine the onset location of air entrainment. In addition, qualitative observations of these processes are made in order to determine the mechanisms leading to air entrainment present in this flow.

Ship performance modelling for least-CO2 emission routes

Decarbonization of maritime transport requires immediate action. In the short term, ship weather routing can provide greenhouse gas emission reductions, even for existing ships and without retrofitting them. Weather routing is based on making optimal use of both envi- ronmental information and knowledge about vessel seakeeping and performance. Combining them at a state-of-the-art level and making use of path planning in realistic conditions can be challenging. To address these topics in an open-source framework, this thesis led to the development of a new module called bateau , and to its combination with the ship routing model VISIR. bateau includes both hull geometry and propulsion modelling for various vessel types. It has two objectives: to predict the sustained speed in a seaway and to estimate the CO2 emission rate during the voyage. Various semi-empirical approaches were used in bateau to predict the ship hydro- and aerodynamical resistance in both head and oblique seas. Assuming that the ship sails at a constant engine load, the involuntary speed loss due to waves was estimated. This thesis also attempted to clarify the role played by the actual representation of the sea state. In particular, the influence of the wave steepness parameter was assessed. For dealing with ships with a greater superstructure, the wind added resistance was also estimated. Numerical experiments via bateau were conducted for both a medium and a large-size container ships, a bulk-carrier, and a tanker. The simulations of optimal routes were carried out for a feeder containership during voyages in the North Indian Ocean and in the South China Sea. Least-CO2 routes were compared to the least-distance ones, assessing the relative CO2 savings. Analysis fields from the Copernicus Marine Service were used in the numerical experiments.

The constancy of global regulation across a species: the concentrations of ppGpp and RpoS are strain-specific in Escherichia coli

Background: Sigma factors and the alarmone ppGpp control the allocation of RNA polymerase to promoters under stressful conditions. Both ppGpp and the sigma factor sigma(S) (RpoS) are potentially subject to variability across the species Escherichia coli. To find out the extent of strain variation we measured the level of RpoS and ppGpp using 31 E. coli strains from the ECOR collection and one reference K-12 strain. Results: Nine ECORs had highly deleterious mutations in rpoS, 12 had RpoS protein up to 7-fold above that of the reference strain MG1655 and the remainder had comparable or lower levels. Strain variation was also evident in ppGpp accumulation under carbon starvation and spoT mutations were present in several low-ppGpp strains. Three relationships between RpoS and ppGpp levels were found: isolates with zero RpoS but various ppGpp levels, strains where RpoS levels were proportional to ppGpp and a third unexpected class in which RpoS was present but not proportional to ppGpp concentration. High-RpoS and high-ppGpp strains accumulated rpoS mutations under nutrient limitation, providing a source of polymorphisms. Conclusions: The ppGpp and sigma(S) variance means that the expression of genes involved in translation, stress and other traits affected by ppGpp and/or RpoS are likely to be strain-specific and suggest that influential components of regulatory networks are frequently reset by microevolution. Different strains of E. coli have different relationships between ppGpp and RpoS levels and only some exhibit a proportionality between increasing ppGpp and RpoS levels as demonstrated for E. coli K-12.

Two-dimensional supersonic nonlinear Schrodinger flow past an extended obstacle

Supersonic flow of a superfluid past a slender impenetrable macroscopic obstacle is studied in the framework of the two-dimensional (2D) defocusing nonlinear Schroumldinger (NLS) equation. This problem is of fundamental importance as a dispersive analog of the corresponding classical gas-dynamics problem. Assuming the oncoming flow speed is sufficiently high, we asymptotically reduce the original boundary-value problem for a steady flow past a slender body to the one-dimensional dispersive piston problem described by the nonstationary NLS equation, in which the role of time is played by the stretched x coordinate and the piston motion curve is defined by the spatial body profile. Two steady oblique spatial dispersive shock waves (DSWs) spreading from the pointed ends of the body are generated in both half planes. These are described analytically by constructing appropriate exact solutions of the Whitham modulation equations for the front DSW and by using a generalized Bohr-Sommerfeld quantization rule for the oblique dark soliton fan in the rear DSW. We propose an extension of the traditional modulation description of DSWs to include the linear ""ship-wave"" pattern forming outside the nonlinear modulation region of the front DSW. Our analytic results are supported by direct 2D unsteady numerical simulations and are relevant to recent experiments on Bose-Einstein condensates freely expanding past obstacles.