•The use of ultra-short baseline (USBL) acoustic technique in subsea is explored.•Proposed method is built upon box-in estimation, which uses only the distance.•Redundant measurements and avoidance ...of angular errors aid in improving accuracy.•Proposed method involves, among others, offset transformation and M−estimation.•As a result, a marker buoy was positioned well within the desired accuracy of 10 m.
Positioning seabed objects in ultra-deep waters is critical in the mapping, exploration, and industrial exploitation of oceans. This paper presents research on a subsea wellhead positioning process for the marking of seabed positions and its subsequent as-built verification. The results indicate that the ultra-short baseline (USBL) acoustic technique can provide static positioning accuracy and precision comparable to those of a long-baseline method (LBL) and significantly reduces the time and cost of the offshore project. The new approach was tested at different stages of the process. First, an innovative offset transformation method, which increases the precision of alignments, was proposed, followed by a step-by-step procedure for determining the positions of marker buoys on the seabed based on spin tests and cardinal heading calibration. Finally, the M−estimation method, which has not yet been applied in subsea engineering, was implemented and proved to be a suitable alternative to the ordinary least squares method.
The Clarion-Clipperton Zone (CCZ) in the tropical East Pacific is a region of interest for deep-sea mining due to its underwater deposits of polymetallic nodules containing economically important ...metals such as nickel, copper, and cobalt. It is also a region of extensive baseline studies aiming to describe the state of the environment, including the biodiversity of the benthic fauna. An abundant component of the abyssal plain ecosystem consists of sessile fauna which encrusts polymetallic nodules and are vulnerable to potential impacts arising from exploitation activities, particularly removal of substrate. Therefore, this fauna is often considered to have key species whose genetic connectivity should be studied to assess their ecological resilience. One such species is Abyssoprimnoagemina Cairns, 2015, a deep-sea coral from the CCZ whose presence in the Interoceanmetal Joint Organization (IOM) claim area has been confirmed during samplings. In this study, we used next-generation sequencing (NGS) to obtain the 18S nuclear rRNA gene and the complete mitochondrial genome of A.gemina from IOM exploration area. The mitogenome is 18,825 bp long and encodes for 14 protein coding genes, 2 rRNAs, and a single tRNA. The two phylogeny reconstructions derived from these data confirm previous studies and display A.gemina within a highly supported cluster of seven species whose mitogenomes are all colinear and of comparable size. This study also demonstrates the suitability of NGS for DNA barcoding of the benthic megafauna of the CCZ, which could become part of the IOM protocol for the assessment of population diversity and genetic connectivity in its claim area.
Geochemical features of the deep-sea sediments from a high polymetallic nodule area in the eastern part of the Clarion-Clipperton Fractures Zone (CCZ), NE Pacific were studied. Box-corer samples from ...six stations in individual depth layers 0–3, 3–5, 5–10, 10–20 cm were collected from 4300–4500 m depth. The deep-sea sediments were classified as clayey-siliceous oozes according to the mineral and grain-size analyses. The chemical composition of the studied samples is compatible with that of pelagic sediments. Manganese content varies from 0.16% to 0.70% being the highest in the geochemically active layer (top 7–12 cm) and decreases with depth. The Mn/Fe ratio, Ba, Co, Ni and Cu have the highest values in the first (0–3) and second (3–5) layers and decrease with depth. REE range is 195.84–357.79 ppm showing low variation between the layers. PAAS-normalized REE patterns show significant enrichment of MREE and HREE with strong negative Ce anomaly and weak positive Eu and Y anomalies. The geochemical characteristics of the studied sediments infer polygenic origin. The redox sensitive oxides and barite presense, Eh values and negative Ce anomaly, indicate oxidizing environment of sediment formation.
Our study is focused on REE and yttrium (REY) geochemistry of pore waters from core-box sediments. The samples were collected from the 0–5 cm, 10–15 cm, 25–30 cm, and 35–40 cm depth intervals of four ...stations of the eastern part of block H_22 of IOM license area of the Clarion-Clipperton Fracture Zone, NE Pacific. The REE studies in marine pore fluids were limited by analytical challenges. The pore water analysis we applied is based on a modern, improved analytical technique (ICP-MS, Perkin-Elmer SCIEX Elan DRC-e) with a cross-flow nebulizer and a spectrometer optimized (RF, gas flow, lens voltage) using a quadrupole cell in a DRC (Dynamic Reaction Cell) mode that allowed us to define the whole suite of REE. The ƩREY values of the samples vary from 4.05 μg/l to 106.34 μg/l. The REE content is at least one order of magnitude higher than the oceanic water. We followed the natural variations of La, Lu, Ce, and Y in absolute concentrations for station 3607. Cerium and Y are slightly enriched around the water-sediment interface, while La and Lu are enriched in the deeper layers. PAAS normalized REY patterns show a pronounced negative Ce/Ce* ratio together with a little MREE and HREY enrichment. The relatively “flat” REE patterns are typical for the shallow open ocean and characterize REE released from the organic matter degradation. We assume that the decomposition of and adsorption on organic matter and oxidation conditions are the main factors for REE fractionation in the pore water. The reason for some scatter in our REY data might be linked to bioturbation that has affected the sediment profiles.
This paper presents an attempt to applying neural networks for assessment of parameters of standard manoeuvrability tests, i.e. circulation test and zig-zag test. Methodological approach to ...application of neural networks as well as applied network structures and neuron activation functions are generally presented. Also, results of simulations performed by means of the elaborated networks are given in comparison with test cases selected at random. In order to analyze and reveal general trends, correlation relationships between results from network simulations and test cases were calculated and are presented as well.
Deep-sea polymetallic nodules have been traditionally considered as a potential resource for Ni, Cu, Mn and Co, however the recent research showed that they contain a large variety of metals, ...including molybdenum, zinc, zirconium, lithium, platinum, titanium, germanium, yttrium, and REEs, which increased their combined value as an alternative supplies for expanding economies and emerging green energy technologies. The highest nodule abundance (more than 10 kg/m^sup 2^) with the high average percentage of metals (at least 2.5 % combined content for Ni+Cu, 0.2% Co, 30% Mn, 0.15% Zn, 0.07% Mo, etc.) were found at seafloor in the eastern equatorial Pacific (ClarionClipperton Fracture Zone, CCZ) and in the central equatorial Indian Ocean. Within the recent decade, the International Seabed Authority (ISA) granted to ten national and multinational entities (Japan, China, Korea, India, Russian Federation, France, Germany, Tonga, Nauru, and Interoceanmetal Joint Organization) exclusive 15-years contracts for polymetallic nodules exploration in ten claim areas, each covering 75000 km^sup 2^ in the international seabed area. The commercial viability of nodule mining has yet to be established, but the size of deposits, the grade of several metals contained in nodules as well as the promising trends in metal market continue to motivate contractors to carry out their exploration activity. This paper discusses the renewed importance of polymetallic nodule in the context of forecasted increasing demands for metals coupled with their environmentally advantages as alternative sources to land-based mining. PUBLICATION ABSTRACT
After signing ship building contract shipyard's design office orders performance of ship resistance and propulsion model tests aimed at, apart from resistance measurements, also determination of ship ...speed, propeller rotational speed and propulsion engine power for the designed ship, as well as improvement of its hull form, if necessary. Range of ship hull modifications is practically very limited due to cost and time reasons. Hence numerical methods, mainly CFD ones are more and more often used for such tests. In this paper consisted of three parts, are presented results of numerical calculations of hull resistance, wake and efficiency of propeller operating in non-homogenous velocity field, performed for research on 18 hull versions of B573 ship designed and built by Szczecin Nowa Shipyard.
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