RV Sonne Cruise 200, 11 Jan-11 Mar 2009. Jakarta - Jakarta

All plate boundaries are divided into segments - pieces of fault that are distinct from oneanother, either separated by gaps or with different orientations. The maximum size of anearthquake on a fault system is controlled by the degree to which the propagating rupture cancross the boundaries between such segments. A large earthquake may rupture a whole segmentof plate boundary, but a great earthquake usually ruptures more than one segment at once.The December 26th 2004 MW 9.3 earthquake and the March 28th 2005 MW 8.7 earthquakeruptured, respectively, 1200–1300 km and 300–400 km of the subduction boundary betweenthe Indian-Australian plate and the Burman and Sumatra blocks. Rupture in the 2004 eventstarted at the southern end of the fault segment, and propagated northwards. The observationthat the slip did not propagate significantly southwards in December 2004, even though themagnitude of slip was high at the southern end of the rupture strongly suggests a barrier at thatplace. Maximum slip in the March 2005 earthquake occurred within ~100 km of the barrierbetween the 2004 and 2005 ruptures, confirming both the physical importance of the barrier,and the loading of the March 2005 rupture zone by the December 2004 earthquake.The Sumatran Segmentation Project, funded by the Natural Environment Research Council(NERC), aims to characterise the boundaries between these great earthquakes (in terms of bothsubduction zone structure at scales of 101-104 m and rock physical properties), record seismicactivity, improve and link earthquake slip distribution to the structure of the subduction zoneand to determine the sedimentological record of great earthquakes (both recent and historic)along this part of the margin. The Project is focussed on the areas around two earthquakesegment boundaries: Segment Boundary 1 (SB1) between the 2004 and 2005 ruptures atSimeulue Island, and SB2 between the 2005 and smaller 1935 ruptures between Nias and theBatu Islands.Cruise SO200 is the third of three cruises which will provide a combined geophysical andgeological dataset in the source regions of the 2004 and 2005 subduction zone earthquakes.SO200 was divided into two Legs. Leg 1 (SO200-1), Jakarta to Jakarta between January 22ndand February 22nd, was composed of three main operations: longterm deployment OBSretrieval, TOBI sidescan sonar survey and coring. Leg 2 (SO200-2), Jakarta to Jakarta betweenFebruary 23rd and March 11th, was composed of two main operations: Multichannel seismicreflection (MCS) profiles and heatflow probe transects

Wind-induced drift of objects at sea: the leeway field method

A method for conducting leeway field experiments to establish the drift properties of small objects (0.1-25 m) is described. The objective is to define a standardized and unambiguous procedure for condensing the drift properties down to a set of coefficients that may be incorporated into existing stochastic trajectory forecast models for drifting objects of concern to search and rescue operations and other activities involving vessels lost at sea such as containers with hazardous material. An operational definition of the slip or wind and wave-induced motion of a drifting object relative to the ambient current is proposed. This definition taken together with a strict adherence to 10 m wind speed allows us to refer unambiguously to the leeway of a drifting object. We recommend that all objects if possible be studied using what we term the direct method, where the object's leeway is studied directly using an attached current meter. We divide drifting objects into four categories, depending on their size. For the smaller objects (less than 0.5 m), an indirect method of measuring the object's motion relative to the ambient current must be used. For larger objects, direct measurement of the motion through the near-surface water masses is strongly recommended. Larger objects are categorized according to the ability to attach current meters and wind monitoring systems to them. The leeway field method proposed here is illustrated with results from field work where three objects were studied in their distress configuration; a 1:3.3 sized model of a 40-ft Shipping container, a World War II mine and a 220 l (55-gallon) oil drum.Comment: 33 pages, 12 figures, 3 table

A towing system for a sensing package: Experiences and plans

The development of a technique for towing standard oceanographic sensors (pressure, temperature, conductivity, and sound velocity) at intermediate depths of less than 1000 m is described. Data show the depth characteristics of the tow and the comparative output from each of the sensors...

[Report of] Specialist Committee V.4: ocean, wind and wave energy utilization

The committee's mandate was :Concern for structural design of ocean energy utilization devices, such as offshore wind turbines, support structures and fixed or floating wave and tidal energy converters. Attention shall be given to the interaction between the load and the structural response and shall include due consideration of the stochastic nature of the waves, current and wind

Efficient control based on a verified model for an autonomous underwater vehicle : a case study of Autonomous Benthic Explorer

Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 1992The Autonomous Benthic Explorer (ABE) is an unmanned underwater vehicle being developed for scientific study of the deep ocean sea:floor. ABE will be completely autonomous from the surface which means that the lifetime of the mission will depend largely on how the vehicle is controlled. An accurate system model is critical for the controller development and trajectory planning. A model of the ABE vehicle dynamics is formulated for surge, heave and pitch motions. These motions in the lon,gitudinal plane are particularly important for the basic ABE trajectories of forward flight, depth changes and maneuvers involving both. A scale model of the ABE vehicle was towed to determine the lift/drag relationships to nonzero angles of attack. The experimental results are used in conjunction with traditional analytical techniques to generate a model of the longitudinal dynamics. The ABE model was studied in simulation over anticipated vehicle trajectories. A proportional plus derivative controller and a sliding mode controller were developed for tracking control. The power consumptions for different controllers and trajectories are examined. The results of this study will be incorporated in the final ABE design.The Office of Naval Research is gratefully acknowledged for its financial support of my graduate education. In addition, this work has been sponsored in part by the National Science Foundation, grant number OCE 8820227

RRS James Cook Cruise 35, 7-19 Jun 2009. Sidescan sonar mapping of the Whittard Canyon, Celtic Margin

James Cook cruise 035 was aimed at the detailed mapping of the Whittard Canyon system along the Celtic Margin (NE Atlantic). In 12 days, &gt;700 km of track-lines were surveyed with the Towed Ocean Bottom Instrument (TOBI, carrying a 30 kHz sidescan sonar system with phase bathymetry capability, an 8 kHz chirp profiler and a magnetometer) and 6130 km2 of shipborne multibeam data was acquired over the 4 main branches of the canyon. This comprehensive and highly detailed dataset will provide new insights in canyon morphology, formation, sediment transport processes and into the resulting spatial distribution of benthic habitats. In addition, the data formed an indispensable base map for the planning of ROV dives during the follow-on cruise JC036.<br/

An experimental investigation into the components of ship resistance

Includes bibliography.This thesis is an experimental investigation into the components of ship resistance. The traditional Froude method of scaling is investigated with reference to the measurement of skin friction and viscous pressure resistance. A literature review is given on the theoretical background and experimental measurement techniques. Two models are used for the experimental work, which sizes are in the geometric ratio of 2,7 to 1. The model form is half a body of revolution with a vertical sided superstructure. The block coefficient of the model is 0,621 and the length to beam ratio is 7. Two surface models and one reflex model are tested. One of the models has 40 pressure tappings located on its hull which are used to measure the total pressure resistance of the model. The components of resistance directly measured are total resistance, total viscous resistance and total pressure resistance. The resistance components inferred are skin friction resistance and wave-making resistance. The deduced skin friction is found to deviate from the Prandtl-von Karman skin friction formulation. The wave-making resistance agrees favourably with the predicted values using Mitchell's integral. The total viscous resistance increases sharply at Reynolds numbers greater than 3 x 10⁶

Modeling and Simulation of Automatic Berthing based on Bow and Stern Thruster Assist for Unmanned Surface Vehicle

In order to solve the technical problems of autonomous berthing of the Unmanned Surface Vehicle (USV), this research has met the requirements of maneuverability berthing under different conditions by effectively using the bow and stern thrusters, which is a technological breakthrough in actual production and life.Based on the MMG model, the maneuverability mathematical model of the USV with bow and stern thruster was established. And the motion simulation of USV maneuvering was carried out through the numerical simulation calculation. Then the berthing plan was designed based on the maneuverability analysis of the USV low-speed motion, and the simulation of automatic berthing for USV was carried out. The research results of this paper can be of certain practical significance for the USV based on the support of the bow and stern thruster in the berthing. At the same time, it also provides a certain theoretical reference for the handling of the USV automatic berthing