scholarly journals Underwater Terrain-Aided Navigation Relocation Method in the Arctic

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Yanji Liu ◽  
Guichen Zhang ◽  
Chidong Che
Keyword(s):  
Autonomous Underwater Vehicle ◽  
System Level ◽  
The Arctic ◽  
Sharp Change ◽  
Motion Information ◽  
Large Area ◽  
Flat Terrain ◽  
Localization Errors ◽  
Underwater Navigation ◽  
Nonlinear Noise

To solve the localization failure problem of terrain-aided navigation (TAN) system of the autonomous underwater vehicle (AUV) caused by large area of underwater flat terrain in the Arctic, a navigation system with relocation part is constructed to enhance the robustness of localization. The system uses particle filter to estimate the AUV’s position and reduce the nonlinear noise disturbance, and the prior motion information is added to avoid the mismatching caused by the similar altitude of low-resolution map. Based on the estimate data and the measured altitude data, the normalized innovation square (NIS) is used to evaluate the differentiation of terrain sequence, and the differentiation is used as a judgment of whether the AUV is in the switch location. A simulation experiment is carried out on the 500 m resolution underwater map of the Arctic. The results show that adding the prior motion information can restrain the divergence of the estimator; NIS can accurately reflect the sharp change of terrain sequence. After the relocation process, the AUV can still maintain the positioning accuracy within 2 km after running 50 km in the area including flat and rough terrain. This research solves the problem of localization errors in the Arctic flat terrain in the system level and provides a solution for the application of underwater navigation in the Arctic.

Adaptive Sampling of Surface Fronts in the Arctic Using an Autonomous Underwater Vehicle

2021 ◽  
pp. 1-10
Author(s):  
Trygve Olav Fossum ◽  
Petter Norgren ◽  
Ilker Fer ◽  
Frank Nilsen ◽  
Zoe Koenig ◽  
...  
Keyword(s):  
Adaptive Sampling ◽  
Autonomous Underwater Vehicle ◽  
Underwater Vehicle ◽  
The Arctic

PROSPECTS FOR THE USE OF GLONASS IN SOLVING SPECIAL PROBLEMS

2021 ◽  
Author(s):  
С.А. ГЕРКО ◽  
С.С. МАРКОВ ◽  
Р.Б. МАЗЕПА
Keyword(s):  
Rapid Development ◽  
Arctic Region ◽  
The Arctic ◽  
High Rise ◽  
Underwater Navigation ◽  
Navigation Equipment ◽  
The Arctic Region

Представлен обзор навигационной аппаратуры потребителей, предназначенной для решения специальных задач, которые в условиях бурного развития навигационных услуг вызывают широкий интерес как у гражданских, так и у военных заказчиков. Рассмотрены следующие специальные задачи: навигационное обслуживание строительства сложных высотных и протяженных объектов; надводная и подводная навигация судов, в том числе в Арктике; и подземная навигация. Показано, что в настоящее время решение этих задач достигло определенного успеха, но все еще остаются проблемы, которые требуют быстрого решения. The article presents an overview of consumer navigation equipment designed to solve special problems. The equipment in conditions of rapid development of navigation services is of wide interest to both civil and military customers. The following special tasks are considered: navigation maintenance of construction of complex high-rise and long facilities; surface and underwater navigation of ships, including in the Arctic region; and underground navigation. It is shown that at present the solution of these problems has achieved some success, but there are still unsolved problems that require a quick solution.

New Evidence of the Late Neopleistocene Peopling of the Lower Ob Valley

2021 ◽  
Vol 49 (1) ◽  
pp. 9-20
Author(s):  
I. D. Zolnikov ◽  
A. A. Anoikin ◽  
E. A. Filatov ◽  
A. V. Vybornov ◽  
A. V. Vasiliev ◽  
...  
Keyword(s):  
Upper Paleolithic ◽  
The Arctic ◽  
Northern Eurasia ◽  
West Siberian Plain ◽  
Faunal Remains ◽  
Human Occupation ◽  
Large Area ◽  
Paleolithic Site ◽  
The North ◽  
Available Information

This study focuses on the early human occupation of the arctic part of the West Siberian Plain and introduces the finds at the Paleolithic site Kushevat (Shuryshkarsky District, Yamal-Nenets Autonomous Okrug), discovered in 2020. Geological and geomorphological characteristics of the Lower Ob region are provided, the chronology of the key Middle and Late Neopleistocene sequences is assessed, and criteria underlying the search for Paleolithic sites in the area are outlined. We describe the discovery and excavations at Kushevat, its stratigraphy and its faunal remains. On the basis of correlation with neighboring key Late Neopleistocene sections with a representative series of absolute dates, the age of the site is estimated at cal 50–35 ka BP. Results of a traceological study of a possibly human-modified reindeer antler are provided. Findings at Kushevat and the available information on the early peopling of northern Eurasia suggest that the boundary of the inhabited part of that region must be shifted ~200 km to the north. The Ob, therefore, is one of the last major Siberian rivers where traces of the Early Upper Paleolithic culture have been found. The discovery of a stratified site in its lower stretch is a milestone in the Paleolithic studies in the region. A large area over which faunal remains are distributed, and the presence of lithics among the surface finds, suggest that Kushevat is a highly prospective site for future archaeological studies of the early stages in the human peopling of the region.

scholarly journals Estimating Underwater Light Regime under Spatially Heterogeneous Sea Ice in the Arctic

2018 ◽  
Vol 8 (12) ◽  
pp. 2693 ◽  
Author(s):  
Philippe Massicotte ◽  
Guislain Bécu ◽  
Simon Lambert-Girard ◽  
Edouard Leymarie ◽  
Marcel Babin
Keyword(s):  
Sea Ice ◽  
Water Column ◽  
Attenuation Coefficient ◽  
Vertical Profile ◽  
Light Field ◽  
Incident Light ◽  
Single Point ◽  
The Arctic ◽  
Large Area ◽  
Average Irradiance

The vertical diffuse attenuation coefficient for downward plane irradiance ( K d ) is an apparent optical property commonly used in primary production models to propagate incident solar radiation in the water column. In open water, estimating K d is relatively straightforward when a vertical profile of measurements of downward irradiance, E d , is available. In the Arctic, the ice pack is characterized by a complex mosaic composed of sea ice with snow, ridges, melt ponds, and leads. Due to the resulting spatially heterogeneous light field in the top meters of the water column, it is difficult to measure at single-point locations meaningful K d values that allow predicting average irradiance at any depth. The main objective of this work is to propose a new method to estimate average irradiance over large spatially heterogeneous area as it would be seen by drifting phytoplankton. Using both in situ data and 3D Monte Carlo numerical simulations of radiative transfer, we show that (1) the large-area average vertical profile of downward irradiance, E d ¯ ( z ) , under heterogeneous sea ice cover can be represented by a single-term exponential function and (2) the vertical attenuation coefficient for upward radiance ( K L u ), which is up to two times less influenced by a heterogeneous incident light field than K d in the vicinity of a melt pond, can be used as a proxy to estimate E d ¯ ( z ) in the water column.

scholarly journals A Behavioral Probabilistic Risk Assessment Framework for Managing Autonomous Underwater Vehicle Deployments

2012 ◽  
Vol 29 (11) ◽  
pp. 1689-1703 ◽  
Author(s):  
Mario Brito ◽  
Gwyn Griffiths ◽  
James Ferguson ◽  
David Hopkin ◽  
Richard Mills ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Autonomous Underwater Vehicle ◽  
Risk Mitigation ◽  
Operational Risk ◽  
Maximum Error ◽  
Underwater Vehicle ◽  
Behavioral Approach ◽  
Mitigation Measures ◽  
The Arctic ◽  
Deep Diving

Abstract The deployment of a deep-diving long-range autonomous underwater vehicle (AUV) is a complex operation that requires the use of a risk-informed decision-making process. Operational risk assessment is heavily dependent on expert subjective judgment. Expert judgments can be elicited either mathematically or behaviorally. During mathematical elicitation experts are kept separate and provide their assessment individually. These are then mathematically combined to create a judgment that represents the group view. The limitation with this approach is that experts do not have the opportunity to discuss different views and thus remove bias from their assessment. In this paper, a Bayesian behavioral approach to estimate and manage AUV operational risk is proposed. At an initial workshop, behavioral aggregation, that is, reaching agreement on the distributions of risks for faults or incidents, is followed by an agreed upon initial estimate of the likelihood of success of the proposed risk mitigation methods. Postexpedition, a second workshop assesses the new data and compares observed to predicted risk, thus updating the prior estimate using Bayes’ rule. This feedback further educates the experts and assesses the actual effectiveness of the mitigation measures. Applying this approach to an AUV campaign in ice-covered waters in the Arctic showed that the maximum error between the predicted and the actual risk was 9% and that the experts’ assessments of the effectiveness of risk mitigation led to a maximum of 24% in risk reduction.

Hydrothermal exploration and astrobiology: oases for life in distant oceans?

2004 ◽  
Vol 3 (2) ◽  
pp. 81-95 ◽  
Author(s):  
Christopher R. German
Keyword(s):  
High Temperature ◽  
Organic Synthesis ◽  
Autonomous Underwater Vehicle ◽  
De Novo ◽  
The Arctic ◽  
Ocean Ridges ◽  
Abiotic Organic Synthesis ◽  
Preliminary Identification ◽  
Slow Spreading ◽  
Hydrothermal Fields

High-temperature submarine hydrothermal fields on Earth's mid-ocean ridges play host to exotic ecosystems with fauna previously unknown to science. Because these systems draw significant energy from chemosynthesis rather than photosynthesis, it has been postulated that the study of such systems could have relevance to the origins of life and, hence, astrobiology. A major flaw to that argument, however, is that modern basalt-hosted submarine vents are too oxidizing and lack the abundant free hydrogen required to drive abiotic organic synthesis and/or the energy yielding reactions that the most primitive anaerobic thermophiles isolated from submarine vent-sites apparently require. Here, however, the progress over the past decade in which systematic search strategies have been used to identify previously overlooked venting on the slow-spreading Mid-Atlantic Ridge and the ultra-slow spreading Arctic and SW Indian Ridges is described. Preliminary identification of fault-controlled venting in a number of these sites has led to the discovery of at least two high-temperature hydrothermal fields hosted in ultramafic rocks which emit complex organic molecules in their greater than 360 °C vent-fluids. Whether these concentrations represent de novo organic synthesis within the hydrothermal cell remains open to debate but it is probable that many more such sites exist throughout the Atlantic, Arctic and SW Indian Oceans. One particularly intriguing example is the Gakkel Ridge, which crosses the floor of the Arctic Ocean. On-going collaborations between oceanographers and astrobiologists are actively seeking to develop a new class of free-swimming autonomous underwater vehicle, equipped with appropriate chemical sensors, to conduct long-range missions that will seek out, locate and investigate new sites of hydrothermal venting at the bottom of this, and other, ice-covered oceans.

PATTERNS OF DIVERSITY IN THE CANADIAN INSECT FAUNA

1993 ◽  
Vol 125 (S165) ◽  
pp. 51-74 ◽  
Author(s):  
H.V. Danks
Keyword(s):  
Species Richness ◽  
Climatic Factors ◽  
Interspecific Interactions ◽  
The Arctic ◽  
Large Area ◽  
The West ◽  
Insect Fauna ◽  
Climatic Trend ◽  
The North ◽  
Historical Factors

AbstractThe diversity of the Canadian insect fauna decreases and its composition (at all taxonomic levels) changes as climates become progressively more harsh toward the north. This climatic trend dominates patterns of diversity, but many other factors interact to produce the observed patterns. In the arctic, species richness is greatest in the west. Farther south, overall species richness is greatest in the west (especially British Columbia), associated with coastal and cordilleran habitats, and to a somewhat smaller degree in the southeast (especially Ontario), associated with deciduous forests and particularly with transitional forests which occupy a large area of southeastern Canada. However, certain taxa are better represented in the west or in the east, depending on present-day habitats and on historical factors. These conclusions, based chiefly on a sample of taxa of different types, are possible only because basic systematic work has been carried out to distinguish and map the species. Preliminary data on numerical patterns, such as the numbers of species relative to different potential resources such as host plants in different zones, tend to suggest that the occurrence of species in the north may depend so heavily on climatic factors that potential resources are not fully exploited and the effects of interspecific interactions on diversity are reduced.

scholarly journals Decision Making About Rural Physiotherapy Service Provision Varies With Sector, Size and Rurality

2015 ◽  
Author(s):  
Robyn Adams ◽  
Anne Jones ◽  
Sophie Lefmann ◽  
Lorraine Sheppard
Keyword(s):  
Decision Making ◽  
Service Provision ◽  
Service Sector ◽  
Decision Makers ◽  
System Level ◽  
Research Approach ◽  
Local Health ◽  
Large Area ◽  
Physiotherapy Service ◽  
Local Health Service

Introduction: Decisions about physiotherapy service provision occur within the context of organisations, locations, and settings. The uniqueness of rural communities means it is important to consider contextual factors when making decisions about rural health services. As literature describing decision making about rural physiotherapy services is limited, this study sought perspectives on service level decision making (SLDM) from a range of stakeholders. The research approach needed to support consideration of both location and the broader health system. Method: A sequential mixed methods approach within a systems theory-case study heuristic provided the framework to explore rural physiotherapy SLDM. The investigation site, a large area of one Australian state, contained a mix of regional, rural, and remote communities. Perspectives on SLDM were obtained through surveys of physiotherapists, colleagues, and managers, with follow up interviews of a purposeful sample of participants. Results: Responses from physiotherapists, colleagues, manager surveys (n=34), and in-depth interviews (n=19) revealed commonalities and differences between sites and sectors. Available skill and expertise were common considerations across sites. Decisions about prioritisation of services occurred in both public and private settings; however, organisational priorities were a greater influence in the public sector and financial viability in the private sector. Service size influenced the perceived degree of autonomy of physiotherapists in SLDM, with physiotherapists in smaller sites having more independence. Directions from health facility management and the increasing need to prioritise services were reflected in physiotherapy responses from larger facilities. National health reforms and state level priorities were noted as influencing factors, as were connection to community, rurality, and the distance from decision makers. Conclusion: This study provides insight into decisions informing rural physiotherapy service provision. Understanding context and diversity is important to understanding local health service decisions. System level influences from macro and meso level decision makers provide the framework within which micro level physiotherapy SLDM occurs. Service sector, size and rurality then further qualify local service options and influence SLDM. Decisions about service provision need to take into consideration the current availability of services, the context of each location and skill mix required.

Changes in the Characteristics of the Profiles of X-Ray Diffraction Lines of Structural Steels in the Elastic Stress Field

2020 ◽  
Vol 992 ◽  
pp. 992-997
Author(s):  
V.P. Gulyaev ◽  
P.P. Petrov ◽  
Ksenia V. Stepanova
Keyword(s):  
Stressed State ◽  
Structural Steel ◽  
Elastic Stress ◽  
Structural Steels ◽  
The Arctic ◽  
Technical Diagnostics ◽  
Sharp Change ◽  
Destructive Testing ◽  
X Ray ◽  
Profile Characteristics

The problems of improving operating procedures and diagnosing the bearing capacity of metal structures designed and operating in the Arctic and subarctic regions of the country with a long period of low climatic temperatures remain unresolved. The paper notes that the development of digital methods of non-destructive testing, primarily X-ray diffractometry methods, can provide technical diagnostics of structures by identifying the features of the deformation of the crystalline structure of structural materials in an elastic stress-strain state. It is shown that the application of the method of X-ray diffractometry of complex polycrystalline structural steels has sufficient resolution to detect changes in the fine structure under the elastically stressed state of the samples. The broadening of the diffraction line (B) profile characterizes the effect of the elastically stressed state of steel samples 08 ps and 09Г2С on the course of microdeformation processes in the surface layers of the metal. The effect of periodic annual temperature fluctuations on the profile characteristics of the diffraction lines of 08 ps structural steel samples was studied experimentally. It is established that low climatic temperatures contribute to the elimination of individual instrumental errors due to the design conditions of the experiment. A sharp change in the true half-width of the profile of diffraction lines (В) at stresses σ ≥ 0.5 σт indicates the minimum possible value of the allowable stress [σ] for structural steel 08 ps.

scholarly journals Potential Consequences Of “Dirty” Arctic Sea Ice

1990 ◽  
Vol 14 ◽  
pp. 355
Author(s):  
Stephanie Pfirman ◽  
Manfred A. Lange ◽  
Tamara S. Ledley
Keyword(s):  
Sea Ice ◽  
Arctic Basin ◽  
Surface Melting ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Ice Melting ◽  
Large Area ◽  
Sea Ice Concentration ◽  
East Greenland Current ◽  
Ice Surface

Observations of high particulate loads on Eurasian Basin sea ice in 1987 raise questions of consequence for sediment budgets, ice melting, ice modeling and remote sensing. Biogenic and lithogenic particles were observed in concentrations high enough to color the ice surface brown over large area (greater than 15 × 15 km2) within the Siberian branch of the Transpolar Drift stream. The sediment is most likely incorporated when ice forms on the Siberian shelf seas, and is concentrated at the ice surface after several years of summer surface melting and biological growth within the Arctic basin. Much of the particle-laden multi-year ice appears to leave the Arctic basin via Fram Strait, depositing its sediment load along the axis of the East Greenland Current. To date, variation in sea-ice particle load has not been taken into consideration when modeling ice thickness or distribution for past or future environmental scenarios, with the exception of soot deposited from nuclear war. Naturally elevated surface-particle concentration may occur if there is increased deposition from long-range or coastal transport of aeolian material, increased sediment input into sea ice which is then exposed to surface melting, and/or increased biogenic productivity on the ice surface. Such conditions may have prevailed during the Younger Dryas. If particle loads become high enough to cause extensive sea-ice melting, changes may be expected in sea-ice concentration and distribution, sea-floor sedimentation rates, and oceanic productivity.

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