The Barny Sentinel trawl-resistant ADCP bottom mount: design,testing, and application

A trawl-resistant bottom mount (TRBM) has been developed to meet the needs of long-term deployment of Acoustic Doppler Current Profilers (ADCPs) and Wave-Tide Gauges in water depths up to 300 m. This paper describes the unit's construction and operation together with practical lessons learned during development, testing, and use that can be applied to comparable platforms. The Barny Sentinel is derived from a larger version developed several years ago at SACLANT Center, now extensively redesigned to incorporate an RDI Sentinel ADCP and a Sea-Bird Wave-Tide Gauge. A concrete ring surrounding the fiberglass instrument housing serves as ballast and impact protection. Two independent recovery modes may be activated by acoustic commands, one of which can operate whether or not the platform is upright. Features have also been included to facilitate recovery by remotely operated underwater vehicle. A sending unit, temporarily attached during launch, provides real time information on platform depth and tilt, and confirms that the platform is properly positioned on the bottom before a launch commitment is made. A series of tests and applications have validated all basic functions and trawl resistance. Platform cost has been kept below that of the on-board instruments, while still maintaining the required high level of recoverability     

In situ tests on backfilling and surrounding host-rock in the case of a radioactive waste disposal in a layered salt formation

In situ experiments carried out by ANDRA in a deep and homogeneous salt layer of a French mine (Amélie mine — Alsace Potash Mines S.A.) tested the behavior of the different components of a multibarrier system, designed for high-level waste disposal and particularly for heat-generating wastes. Canisters were placed in blind boreholes.

The experimental field is located at a depth of 520 m where two major tests have been carried out since 1987. The first test (1987–1989) tested the backfilling by heating different types of crushed salt (max. 130°C) emplaced in large-diameter boreholes. One hole remained empty as a control. The second experiment started in 1989 with the opening of a gallery and the boring of three different boreholes (7 m depth, 250 mm diameter) where the annulus between the cylindrical heating cell and the salt mass differs fundamentally in configuration: as tight as possible, empty, or backfilled with crushed salt. The first configuration was tested at the end of 1991.

In both test fields, a complete series of measurements has been carried out to record temperatures, pressures and deformations on the heating devices, as well as in the surrounding media. Backfill and host rock are monitored with sensors placed in different boreholes. High-resolution tiltmeters and accurate levelling complete the field of investigations. Thermo-mechanical behavior and the properties of the materials have been considered in detail using laboratory test results. Calculations showed how thermo-mechanical interactions behave and generally agreed in a satisfactory manner with the measurements of the test field.

Finally, after cooling and dismantling of the experiment, the microscopic change of the different crushed salts used for the backfilling is analysed.     

Morphotectonics of the Mongolia-Siberian mountain belt

The mountains of north-eastern Inner Asia comprise the Mongolia-Siberian orogenic belt which has a complex structure. The southern flank of the belt consists of a chain of large domal uplifts. The Baikal rift zone is located on the northern flank. The central segment is composed of zones of linear warping. The tectonic landforms rest on a large domal basement uplift. The morphology of the latter is paragenetically connected with the shape of the asthenolith underlying the belt. The neotectonic zones are also connected with the deep structure elements.The Mongolia-Siberian mountain belt is a group of orogenic forms typical of intracontinental mountain areas.     

3D chemical model for geological macromolecules

This study defines a chemical representation of the kerogen macromolecule based on data from physicochemical analyses. The model should permit: creation of various schematic drawings representing an average macromolecule; future integration of new analytical results (for instance on structures of biomarkers or biopolymers); and determination of the distribution of chemical bonds.The models developed in this study can be represented in a 3D space, using classical chemical symbols, in the form of cyclic groups linked to each other by aliphatic chains. One cyclic group is a connected set of aromatic, naphthenoaromatic or naphthenic rings. These cyclic groups are constructed using basic elements such as atoms and bonds defined by their length and direction.Modeling of kerogen is done in three successive steps. A library is first created to define atoms, bonds and cyclic groups. Secondly, starting from a set of equations describing the analytical results, cyclic and aliphatic groups are chosen in the appropriate stoechiometric amount to match the analytical data. Finally the construction is done: cyclic groups are placed randomly in a 3D space, connections are made by aliphatic chains, and functional groups are added.The molecular modeling software Xmol^TM can be operated on APOLLO stations. It allows the creation of libraries, the calculation of chemical bonds corresponding to the analyses and the construction of macromolecules. An example is given for a type III kerogen at the beginning of diagenesis.