17 research outputs found
Autonomous and remotely operated vehicle technology for hydrothermal vent discovery, exploration, and sampling
Author Posting. © Oceanography Society, 2007. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 20, 1 (2007): 152-161.Autonomous and remotely operated underwater vehicles play
complementary roles in the discovery, exploration, and detailed
study of hydrothermal vents. Beginning with clues provided
by towed or lowered instruments, autonomous underwater vehicles
(AUVs) can localize and make preliminary photographic
surveys of vent fields. In addition to finding and photographing
such sites, AUVs excel at providing regional context through
fine-scale bathymetric and magnetic field mapping. Remotely
operated vehicles (ROVs) enable close-up inspection, photomosaicking,
and tasks involving manipulation of samples and
instruments. Increasingly, ROVs are used to conduct in situ
seafloor experiments. ROVs can also be used for fine-scale
bathymetric mapping with excellent results, although AUVs are
usually more efficient in such tasks
Mid-ocean ridge exploration with an autonomous underwater vehicle
Author Posting. © Oceanography Society, 2007. This article is posted here by permission of Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 20, 4 (2007): 52-61.Human-occupied submersibles, towed
vehicles, and tethered remotely operated
vehicles (ROVs) have traditionally been
used to study the deep seafloor. In recent
years, however, autonomous underwater
vehicles (AUVs) have begun to replace
these other vehicles for mapping and
survey missions. AUVs complement the
capabilities of these pre-existing systems,
offering superior mapping capabilities,
improved logistics, and better utilization
of the surface support vessel by allowing
other tasks such as submersible operations,
ROV work, CTD stations, or multibeam
surveys to be performed while the
AUV does its work. AUVs are particularly
well suited to systematic preplanned surveys
using sonars, in situ chemical sensors,
and cameras in the rugged deep-sea
terrain that has been the focus of numerous
scientific expeditions (e.g., those to
mid-ocean ridges and ocean margin settings).
The Autonomous Benthic Explorer
(ABE) is an example of an AUV that has
been used for over 20 cruises sponsored
by the National Science Foundation
(NSF), the National Oceanic and
Atmospheric Administration (NOAA)
Office of Ocean Exploration (OE), and
international and private sources. This
paper summarizes NOAA OE-sponsored
cruises made to date using ABE
Diverse styles of submarine venting on the ultraslow spreading Mid-Cayman Rise
Author Posting. © The Authors, 2010. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America 107 (2010): 14020-14025, doi:10.1073/pnas.1009205107.Thirty years after the first discovery of high-temperature submarine venting, the
vast majority of the global Mid Ocean Ridge remains unexplored for hydrothermal
activity. Of particular interest are the world’s ultra-slow spreading ridges which were the
last to be demonstrated to host high-temperature venting, but may host systems
particularly relevant to pre-biotic chemistry and the origins of life.
Here we report first evidence for diverse and very deep hydrothermal vents along the
~110 km long, ultra-slow spreading Mid-Cayman Rise. Our data indicate that the Mid-
Cayman Rise hosts at least three discrete hydrothermal sites, each representing a different
type of water-rock interaction, including both mafic and ultra-mafic systems and, at
~5000 m, the deepest known hydrothermal vent. Although submarine hydrothermal
circulation, in which seawater percolates through and reacts with host lithologies, occurs
on all mid-ocean ridges, the diversity of vent-types identified here and their relative
geographic isolation make the Mid-Cayman Rise unique in the oceans. These new sites
offer prospects for: an expanded range of vent-fluid compositions; varieties of abiotic
organic chemical synthesis and extremophile microorganisms; and unparalleled faunal
biodiversity - all in close proximity.This research was funded
through NASA (ASTEP) and WHOI (Ocean Ridge Initiative)
Pump it Up workshop report
Workshop held 28-29 September 2017, Cape Cod, MAA two-day workshop was conducted to trade ideas and brainstorm about how to advance our understanding of the ocean’s biological pump. The goal was to identify the most important scientific issues that are unresolved but might be addressed with new and future technological advances
Electrochemical methods for speciation of trace elements in marine waters. Dynamic aspects
The contribution of electrochemical methods
to the knowledge of dynamic speciation of toxic trace elements in marine waters is critically reviewed. Due to the importance
of dynamic considerations in the interpretation of the electrochemical signal, the principles and recent developments of kinetic features in the interconversion of metal complex species will be presented. As dynamic electrochemical
methods, only stripping techniques (anodic stripping voltammetry and stripping chronopotentiometry) will be used because they are the most important for the
determination of trace elements. Competitive ligand ex- change-adsorptive cathodic stripping voltammetry, which should be considered an equilibrium technique rather than a dynamic method, will be also discussed because the complexing parameters may be affected by some kinetic limitations if equilibrium before analysis is not attained and/or the flux of the adsorbed complex is in fluenced by the lability of the natural complexes in the water sample. For a correct data interpretation and system characterization the comparison of results obtained from different techniques seems essential in the articulation of a serious discussion of their meaning
Impacts of Hydrostatic Pressure on Distributed Temperature-Sensing Optical Fibers for Extreme Ocean and Ice Environments
Optical fiber is increasingly used for both communication and distributed sensing of temperature and strain in environmental studies. In this work, we demonstrate the viability of unreinforced fiber tethers (bare fiber) for Raman-based distributed temperature sensing in deep ocean and deep ice environments. High-pressure testing of single-mode and multimode optical fiber showed little to no changes in light attenuation over pressures from atmospheric to 600 bars. Most importantly, the differential attenuation between Stokes and anti-Stokes frequencies, critical for the evaluation of distributed temperature sensing, was shown to be insignificantly affected by fluid pressures over the range of pressures tested for single-mode fiber, and only very slightly affected in multimode fiber. For multimode fiber deployments to ocean depths as great as 6000 m, the effect of pressure-dependent differential attenuation was shown to impact the estimated temperatures by only 0.15 °K. These new results indicate that bare fiber tethers, in addition to use for communication, can be used for distributed temperature or strain in fibers subjected to large depth (pressure) in varying environments such as deep oceans, glaciers and potentially the icy moons of Saturn and Jupiter
In situ observation of sponge trails suggests common sponge locomotion in the deep central Arctic
In 2016, the research ice-breaker Polarstern surveyed the submerged peaks of the permanently ice-covered Langseth Ridge, a tectonic feature comprising the Karasik seamount and two deeper seamount peaks, abutting the Gakkel ultra-slow spreading ridge (87°N 62°E to 85.5°N 57.4°E)1. A towed marine camera sled and a hybrid remotely operated vehicle revealed these peaks to be covered by a dense demosponge community, at first glance reminiscent of North Atlantic Geodia grounds (sensu2). Sponges were observed on top of a thick layer of spicule mat (Figure 1 and Video S1), intermixed with underlying layers of empty siboglinid tubes and bivalve shells, a substrate covering almost the entire seafloor. We observed trails of densely interwoven spicules connected directly to the underside or lower flanks of sponge individuals (Figure 1), suggesting these trails are traces of motile sponges. This is the first time abundant sponge trails have been observed in situ and attributed to sponge mobility. Given the low primary production in this permanently ice-covered region, these trails may relate to feeding behavior and/or a strategy for dispersal of juveniles. Such trails may remain visible for long periods given the regionally low sedimentation rates
On the analysis of self-adaptive evolutionary algorithms
Due to the flexibility in adapting to different fitness landscapes, self-adaptive evolutionary algorithms (SA-EAs) have been gaining popularity in the recent past. In this paper, we postulate the properties that SA-EA operators should have for successful applications. Specifically, population mean and variance of a number of SA-EA operators, such as various real-parameter crossover operators and self-adaptive evolution strategies, are calculated for this purpose. In every case, simulation results re shown to verify the theoretical calculations. The postulations and population variance calculations explain why self-adaptive GAs and ESs have shown similar performance in the past and also suggest appropriate strategy parameter values which must be chosen while applying and comparing different SA-EAs. (orig.)Available from TIB Hannover: RR 8071(99-69)+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman