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1
Grumondz, V. T., R. V. Pilgunov, M. V. Vinogradov, and N. V. Maykova. "Lateral Motion of Towed Underwater Vehicle within the Problem of Continental Shelf Monitoring." Herald of the Bauman Moscow State Technical University. Series Mechanical Engineering, no. 1 (130) (February 2020): 56–69. http://dx.doi.org/10.18698/0236-3941-2020-1-56-69.
Повний текст джерелаАнотація:
Lateral motion dynamics was studied of a robotic towed underwater system designed to monitor the continental shelf and consisting of a towed vehicle and a tow wireline. In regard to underwater vehicles of the type in question, it is quite correct to represent spatial motion in the form of a super-position consisting of two flat motions, i.e., longitudinal motion in the vertical plane and lateral motion in the horizontal plane. Dynamics of the towed system longitudinal motion within the monitoring problem was considered in a previously published work by the authors. The present work is its natural continuation and development traditionally accepted in the problems of the underwater vehicles spatial motion mechanics. Diagram of the towed vehicle operation and its hydrodynamic characteristics are presented; besides, mathematical model of a wireline and also a model of the wireline-towed vehicle system lateral motion were constructed. Probable steady system motions were analyzed, issues of balancing, as well as those of the towed vehicle dynamic stability when moving at a constant depth were considered. Results of numerical calculations were provided. The results obtained were considered in conjunction with the results of the authors' above mentioned work related to the towed vehicle longitudinal motion and make it possible to select such system parameters that provide the specified character of spatial movements in the process of monitoring the continental shelf taking into consideration the need to perform turns in the horizontal plane at changing directions and to ensure vertical maneuvers when avoiding underwater obstacles.
2
Kinsey, James C., Maurice A. Tivey, and Dana R. Yoerger. "Dynamics and navigation of autonomous underwater vehicles for submarine gravity surveying." GEOPHYSICS 78, no. 3 (May 1, 2013): G55—G68. http://dx.doi.org/10.1190/geo2012-0181.1.
Повний текст джерелаАнотація:
We investigated the effect of autonomous underwater vehicle (AUV) dynamics and navigation on underway submarine gravimetry. Our research was motivated by the need to obtain spatially dense marine gravity measurements close to the source of subkilometer-scale geologic features in the shallow oceanic crust. Such measurements have been previously obtained, for instance, with piloted submarines and towed sleds; however, the high cost and, in the case of on-bottom measurements, poor spatial sampling preclude routine acquisition of these measurements. Continuous underway gravity surveys with AUVs is a compelling cost-effective option, but this method requires separating the AUV accelerations from the measured gravity. We show that AUVs with a large distance between the center of buoyancy and the center of gravity have lower vertical accelerations than torpedo-shaped AUVs and consequentially are better suited for underway gravity surveys. Furthermore state estimators, which combine sensor measurements and models of the vehicle’s motion, provide superior estimates of the vehicle’s vertical accelerations than methods used in previous underway submarine gravity surveys. We simulated the use of these navigation methods in detecting dike swarms at the East Pacific Rise. Analysis showed that we can shorten filters used in reducing gravity data and consequentially provide improved measurements of the free-water anomaly with a minimal detectable spatial wavelength approximately 65% lower than previously reported results.
3
Olden, Julian D., Oliver Miler, and Alexander Bijaye. "Lake-wide mapping of littoral habitat using underwater videography." Knowledge & Management of Aquatic Ecosystems, no. 423 (2022): 18. http://dx.doi.org/10.1051/kmae/2022018.
Повний текст джерелаАнотація:
Littoral zones − referring to benthic areas above the light compensation depth − provide numerous ecosystem functions, including mediating light, temperature, and nutrient dynamics, and supporting important foraging and refuge areas for macroinvertebrates, fishes and water birds. Habitat assessments of littoral zones remain fundamental to lake and fisheries management, however traditional field surveys are time-intensive and limited in their spatial extent, whereas desktop evaluations using remote sensing and aerial imagery are cost prohibitive and require considerable data processing expertise. In light of these challenges, this study demonstrated the ability to use simple, cost-effective underwater videography to conduct lake-wide spatially-continuous assessments of littoral habitat. For lakes across a gradient of shoreline and riparian development in northwestern United States, we map the areal coverage of macrophytes, coarse woody habitat, bottom substrates, and artificial structures in littoral zones. Underwater videography represents a relevant tool for environmental monitoring because it allows for the estimation of littoral habitats at fine spatial grains across broad spatial extents. Data can also be obtained rapidly and at relatively low cost, providing a permanent record of habitat conditions that can used to monitor trends over time.
4
Garus, Jerzy. "Control-Oriented Modelling of Spatial Motion of Autonomous Underwater Vehicle." Solid State Phenomena 196 (February 2013): 109–16. http://dx.doi.org/10.4028/www.scientific.net/ssp.196.109.
Повний текст джерелаАнотація:
Modelling of three-dimensional motion of an underwater vehicle along a time-varying reference trajectory with predefined speed profiles is presented in the paper. A nonlinear mathematical model with unknown nonlinearities describes the vehicle’s dynamics. Command signals are generated by an adaptive autopilot consisting of three independent controllers with a parameter adaptation law implemented. A control performance is guaranteed by suitably choosing design parameters. Selected results of computer simulations are inserted to demonstrate quality and effectiveness of the approach.
5
Santhakumar, M. "Proportional-Derivative Observer-Based Backstepping Control for an Underwater Manipulator." Mathematical Problems in Engineering 2011 (2011): 1–18. http://dx.doi.org/10.1155/2011/397092.
Повний текст джерелаАнотація:
This paper investigates the performance of a new robust tracking control on the basis of proportional-derivative observer-based backstepping control applied on a three degrees of freedom underwater spatial manipulator. Hydrodynamic forces and moments such as added mass effects, damping effects, and restoring effects can be large and have a significant effect on the dynamic performance of the underwater manipulator. In this paper, a detailed closed-form dynamic model is derived using the recursive Newton-Euler algorithm, which extended to include the most significant hydrodynamic effects. In the dynamic modeling and simulation, the actuator and sensor dynamics of the system are also incorporated. The effectiveness of the proposed control scheme is demonstrated using numerical simulations along with comparative study between conventional proportional-integral-derivative (PID) controls. The results are confirmed that the actual states of joint trajectories of the underwater manipulator asymptotically follow the desired trajectories defined by the reference model even though the system is subjected to external disturbances and parameter uncertainties. Also, stability of the proposed (model reference control) control scheme is analyzed.
6
Zhang, Junhao, Yinglong Chen, Yi Liu, and Yongjun Gong. "Dynamic Modeling of Underwater Snake Robot by Hybrid Rigid-Soft Actuation." Journal of Marine Science and Engineering 10, no. 12 (December 5, 2022): 1914. http://dx.doi.org/10.3390/jmse10121914.
Повний текст джерелаАнотація:
For decades, underwater vehicles have been performing underwater operations, which are critical to the development and upgrading of underwater robots. With the advancement of technology, various types of robots have been developed. The underwater robotic snake is a bioinspired addition to the family of underwater robotic vehicles. In this paper, we propose an innovative underwater snake robot actuated by rigid propulsions and soft joints, which can improve the swimming efficiency and flexibility of the robot and reduce the probability of collision leading to damage. Existing math models of robotic snakes typically incorporate only planar motion, rarely considering spatial motion. So, we formulate a complete three-dimensional dynamic model for the robotic snake, which is extended by deriving expressions for the geometric Jacobians. This modeling approach is well suited since it provides compact matrix expressions and easy implementation. We use the constant curvature method to describe the configuration of the soft joint, use the Lagrangian method to obtain its dynamic characteristics, and focus on deriving the visco-hyperelastic mechanical energy of the soft material. Next, the local dynamics of soft members are extended as a nonholonomic constraint form for modeling the snake robot. Finally, the multi-modal swimming behavior of the robot has been verified by simulations, including forward and backward rectilinear motion, yaw turning, pitch motion, and spiral rising motion. The overall results demonstrate the effectiveness and the versatility of the developed dynamic model in the prediction of the robot trajectory, position, orientation, and velocity.
7
Benoit-Bird, Kelly J., and Whitlow W. L. Au. "Spatial dynamics of a nearshore, micronekton sound-scattering layer." ICES Journal of Marine Science 60, no. 4 (January 1, 2003): 899–913. http://dx.doi.org/10.1016/s1054-3139(03)00092-4.
Повний текст джерелаАнотація:
AbstractIn the Hawaiian Islands, there is a distinct resident community of micronekton, distributed along a narrow band where the upper underwater slopes of the islands meet the oceanic, mesopelagic environment. This mesopelagic boundary community serves as an important food resource to many animals. The goal of this work was to examine spatial heterogeneity of the Hawaiian mesopelagic boundary biomass at a range of scales, in the context of its diel vertical and horizontal migrations. A modified echosounder was used to sample the coasts of three Hawaiian Islands, permitting a range of scales from several meters to several kilometers to be assessed rapidly. The Hawaiian mesopelagic boundary community fits the hierarchical model of patch structure with patches within patches that are part of a larger-scale matrix of patches. Large differences in the overall distribution patterns of the mesopelagic boundary community exist along with a wide range of overall mesopelagic-animal densities. High animal-density locations have boundary-community layers with a large (kilometers) horizontal extent, and low animal-density locations have small (tens of meters), discrete patches. Higher animal-density locations are also more complex than low-density sites, with more levels of patchiness within the same range of spatial scales. Both time of day and distance from shore significantly affected the geometric and density characteristics as well as the distribution of aggregations within the boundary layer. Horizontal and vertical structures of the mesopelagic boundary community are also coupled. In high-density sites, there is strong vertical layering in acoustic-scattering strength while in low-density sites vertical acoustic structure is absent. The differences observed in the distribution of the mesopelagic boundary community at different levels of overall mesopelagic-animal density suggest biological forcing as the dominant mechanism. A description of heterogeneity in the mesopelagic boundary community in Hawaii is the first step in understanding its importance to both neritic and oceanic ecosystems and its potential for linking these two systems.
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Borsje, Bas, Maurits Kruijt, Jebbe Van der Werf, Suzanne Hulscher, and Peter Herman. "MODELING BIOGEOMORPHOLOGICAL INTERACTIONS IN UNDERWATER NOURISHMENTS." Coastal Engineering Proceedings 1, no. 32 (January 29, 2011): 104. http://dx.doi.org/10.9753/icce.v32.sediment.104.
Повний текст джерелаАнотація:
To prevent sandy coastlines from further erosion, nourishments are executed in which sand is usually put underwater at the foreshore. Waves and currents transport the sand on the beach and in this way stabilize the coastal profile. Little is known about the interactions of these so-called shoreface nourishments with the benthic populations inhabiting the coastal strip. Benthos is affected by the nourishments, but benthic populations could in turn affect the morphological evolution of the nourished coast. Monitoring has shown that the benthic community will mainly recovery after ca. 1 year. However, the impact of benthos on the sediment dynamics and hydrodynamics is unknown. In this paper we focus on tube building worms, which have a large abundance in the foreshore, live in patches of several square meters in diameter and protrude several centimeters from the sediment in the water column. Tube building worms are included in a numerical modeling tool (Delft3D), by explicitly accounting for the influence of cylindrical structures on drag and turbulence by an extra source term of friction force in the momentum equation and an extra source term of Total Kinetic Energy (TKE) and turbulent energy dissipation in the k-ε equations respectively. The model is validated against field and flume experiments and it shows a significant influence on flow velocities near the bed, bed shear stress and bed-load transport rates. Moreover, model results reveal that tube building worms are able to stabilize nourishments and slow down the migration of the outer breaker bar. Present model explorations indicate that future research should focus on the measurement of the patchy distribution of bio-engineers in the foreshore and their impact on the sediment dynamics and hydrodynamics. Such knowledge will enable process based modeling of the spatial and temporal variation in biological activity on the morphological development of the coastal profile and also it will lead to validation of the proposed model with field measurements.
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Lebid, Oleksii G. "Five-mode quasilinear model of nonlinear dynamics of extended system." Environmental safety and natural resources 38, no. 2 (June 30, 2021): 104–20. http://dx.doi.org/10.32347/2411-4049.2021.2.104-120.
Повний текст джерелаАнотація:
Distributed systems are widely used in practice. These are cosmic ligaments in the near-Earth space with a length of tens of kilometers. They approximate reinforced concrete piles in the soil when calculating the stress-strain state and assessing the technical condition; pipelines both in air and in liquid, underwater towed systems. Known underwater airlift systems of great length for the extraction of minerals (nodules) from the ocean floor with a length of 5-10 km. To solve the problems of the dynamics of such systems in various environments, the well-known mathematical models are not quite correct from the point of view of taking into account the variety of wave processes. It determines the need to build refined wave models. A new quasilinear mathematical model, which describes the nonlinear four-mode dynamics of the distributed system in the spatially inhomogeneous field of mass and surface forces, has been obtained. It is described by a nonlinear system of twelve first-order partial differential equations. For it, the principles of ultimate and hyperbolicity are fulfilled. Together with the boundary and initial conditions, it can be used to describe dynamics and statics of geometrically and physically nonlinear rod elements, piles in the ground, crane equipment ropes, mine lifts, aerial cableways, towed systems in liquid and gas flow, etc. For two-mode spatial reduction of the model, the theorem about correctness of Cauchy problem has been considered. As a result of the calculations, the earlier assumptions about the movement of the cable along its initial configuration were changed as the length of the cable changed. It has been found out that this assumption is only true for the initial transition participant. It is also established that at a given tachogram in the configuration of the towed line, there is a point of inflection, which shifts from top to bottom when lifting it. It can be a factor in the looping, contributing to the breakage of the cable system during towing.
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Jiménez-Romero, Raúl, Luis Miguel Fernández-Salas, Desirée Palomino, Ricardo Félix Sánchez-Leal, and Yolanda Vila. "Discovering the Fine-Scale Morphology of the Gulf of Cádiz: An Underwater Imaging Analysis." Journal of Marine Science and Engineering 10, no. 5 (May 10, 2022): 651. http://dx.doi.org/10.3390/jmse10050651.
Повний текст джерелаАнотація:
The dense and deep water flow that leaves the Mediterranean Sea to the Atlantic flows through the upper and middle slope of the Gulf of Cádiz as a powerful bottom stream that models and interacts with bathymetry. The detailed analysis of underwater images, obtained with a photogrammetric sled in the central area of the upper and middle slope of the Gulf of Cádiz, together with multibeam bathymetry and oceanographic and sediment types data, has allowed conducting a detailed study of the seafloor microtopography and the predominant oceanographic dynamics in the study area. Different fine-scale spatial bedforms were identified, such as ripples, dunes, burrows, mounds, obstacle marks, rock bottoms, and low-roughness bottoms using underwater images. Besides, a geostatistical study of the different video transects studied was carried out and allowed us to differentiate three types of bottoms depending on the processes that affect their microtopography.
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Liu, Li, Tao Yao, Xin Hu, Chunjie Zhou, Dianli Hou, Shulin Feng, and Hongyong Yang. "Distributed State Estimation for Dynamic Positioning Systems with Uncertain Disturbances and Transmission Time Delays." Complexity 2020 (July 20, 2020): 1–15. http://dx.doi.org/10.1155/2020/7698504.
Повний текст джерелаАнотація:
The dynamic positioning system of unmanned underwater vehicles (UUVs) is a complex and large-scale system mainly due to the nonlinear dynamics, uncertainty in model parameters, and external disturbances. With the aid of the bio-inspired computing (BIC) method, the designed three-dimensional (3D) spatial positioning system is used for enlarging communication constraints and increasing signal coordination processing. With the growing of measurement scales, the issue of the networked high-precision positioning has been developed rapidly. Then, an information fusion estimation approach is presented for the distributed networked systems with data random transmission time delays and lost and disordered packets. To reduce the communication burden, an adaptive signal selection scheme is employed to reorganize the measurement sequence, and the parameter uncertainties as well as cross-correlated noise are used to describe the uncertain disturbances. Moreover, a reoptimal weighted fusion state estimation is designed to alleviate the information redundancy and maintain higher measurement accuracy. An illustrative example obtained from the 3D spatial positioning system is given to validate the effectiveness of the proposed method.
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Råman Vinnå, Love, Damien Bouffard, Alfred Wüest, Stéphanie Girardclos, and Nathalie Dubois. "Assessing Subaquatic Mass Movement Hazards: an Integrated Observational and Hydrodynamic Modelling Approach." Water Resources Management 34, no. 13 (September 10, 2020): 4133–46. http://dx.doi.org/10.1007/s11269-020-02660-y.
Повний текст джерелаАнотація:
Abstract High-resolution lake and reservoir bathymetric surveys can pinpoint locations that may experience underwater landslides (subaquatic sedimentary mass movements). These can pose a risk to underwater and shoreline infrastructure. This paper outlines an approach for using spatial variation in sedimentary patterns to identify areas susceptible to subaquatic mass movements in lakes and reservoirs. This study focusses on Lake Biel (Switzerland), which has experienced a protracted history of upstream alteration of river flow. Altered flow patterns increase risk of unstable sedimentary features and subaquatic mass movements. Data from sediment traps and cores, Acoustic Doppler Current Profilers and results from a 3D hydrodynamic model gave a consistent picture of spatial and temporal variation in weather-related sedimentation. Erosion caused by short-term rain events contributes the largest proportion of sediments to the lake. Strong rain events combine with typical wind patterns to drive lake circulation. The net effect results in preferential sedimentation onto a steeply sloping shelf prone to subaquatic slides. The integrated approach outlined here incorporates short- and long-term sediment dynamics to provide a systematic assessment of lake sedimentation and potential mass movement hazards. This research represents a first step in developing a risk-evaluation tool for aquatic hazard evaluation.
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Hall, Karina C., Anthony J. Fowler, Michael C. Geddes, and Julian D. Taylor. "Predictable spatiotemporal dynamics of a dense cuttlefish spawning aggregation increases its vulnerability to exploitation." ICES Journal of Marine Science 75, no. 1 (June 13, 2017): 221–34. http://dx.doi.org/10.1093/icesjms/fsx099.
Повний текст джерелаАнотація:
Abstract The giant Australian cuttlefish, Sepia apama, forms a dense spawning aggregation at a single known location across its wide southern Australian distribution. After a rapid increase in fishing pressure on the aggregation in the late 1990s, a series of fishing closures were introduced before any biological information could be collected. We surveyed the habitats, timing, and spatial distribution of the spawning aggregation over 4 years, using underwater visual transects and passive tagging, to assess the suitability of the closures. We found that the annual aggregation was both temporally (April–August) and spatially (over 8 km of coastline) localized and predictable, with a consistent peak in abundances in late May–early June. Cuttlefish densities were generally highest over the shallow, broken bedrock habitat, which was more extensive in several sites left open to fishing. Although the original closure covered about 43% of the hard substrate, it accounted for only 23–37% of the total cuttlefish abundance. The extremely high densities recorded during this study verified that this is a massive spawning aggregation for cuttlefish species worldwide, and that it could be highly vulnerable to overexploitation in the absence of adequate protection, because it is so spatiotemporally predictable and localized.
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Lopez-Vazquez, Vanesa, Jose Manuel Lopez-Guede, Simone Marini, Emanuela Fanelli, Espen Johnsen, and Jacopo Aguzzi. "Video Image Enhancement and Machine Learning Pipeline for Underwater Animal Detection and Classification at Cabled Observatories." Sensors 20, no. 3 (January 28, 2020): 726. http://dx.doi.org/10.3390/s20030726.
Повний текст джерелаАнотація:
An understanding of marine ecosystems and their biodiversity is relevant to sustainable use of the goods and services they offer. Since marine areas host complex ecosystems, it is important to develop spatially widespread monitoring networks capable of providing large amounts of multiparametric information, encompassing both biotic and abiotic variables, and describing the ecological dynamics of the observed species. In this context, imaging devices are valuable tools that complement other biological and oceanographic monitoring devices. Nevertheless, large amounts of images or movies cannot all be manually processed, and autonomous routines for recognizing the relevant content, classification, and tagging are urgently needed. In this work, we propose a pipeline for the analysis of visual data that integrates video/image annotation tools for defining, training, and validation of datasets with video/image enhancement and machine and deep learning approaches. Such a pipeline is required to achieve good performance in the recognition and classification tasks of mobile and sessile megafauna, in order to obtain integrated information on spatial distribution and temporal dynamics. A prototype implementation of the analysis pipeline is provided in the context of deep-sea videos taken by one of the fixed cameras at the LoVe Ocean Observatory network of Lofoten Islands (Norway) at 260 m depth, in the Barents Sea, which has shown good classification results on an independent test dataset with an accuracy value of 76.18% and an area under the curve (AUC) value of 87.59%.
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Sun, Xiu Jun, Jian Shi, and Yan Yang. "Neural Networks Based Attitude Decoupling Control for AUV with X-Shaped Fins." Advanced Materials Research 819 (September 2013): 222–28. http://dx.doi.org/10.4028/www.scientific.net/amr.819.222.
Повний текст джерелаАнотація:
Attitude control in three-dimensional space for AUV (autonomous underwater vehicle) with x-shaped fins is complicated but advantageous. Yaw, pitch and roll angles of the vehicle are all associated with deflection angle of each fin while navigating underwater. In this paper, a spatial motion mathematic model of the vehicle is built by using theorem of momentum and angular momentum, and the hydrodynamic forces acting on x-shaped fins and three-blade propeller are investigated to clarify complex principle of the vehicle motion. In addition, the nonlinear dynamics equation which indicates the coupling relationship between attitude angles of vehicle and rotation angles of x-shaped fins is derived by detailed deduction. Moreover, a decoupling controller based on artificial neural networks is developed to address the coupling issue exposed in attitude control. The neural networks based controller periodically calculates and outputs deflection angles of fins according to the attitude angles measured with magnetic compass, thus the vehicles orientation can be maintained. By on-line training, twenty four weights in this controller converged according to index function.
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Morton, Jason K., and William Gladstone. "Spatial, temporal and ontogenetic variation in the association of fishes (family Labridae) with rocky-reef habitats." Marine and Freshwater Research 62, no. 7 (2011): 870. http://dx.doi.org/10.1071/mf10315.
Повний текст джерелаАнотація:
Habitat variability is an important factor structuring fish assemblages of rocky reefs in temperate Australia. Accepting the generality of this model requires that habitat-related variation is consistent through time, across multiple spatial scales, and applies to all life-history stages. We used repeated underwater visual surveys at multiple spatial scales over a 22-month period to test whether three distinct rocky-reef habitats had different wrasse assemblages and whether these assemblages were subject to spatial, temporal and ontogenetic variability. Overall, the strongest and most consistent habitat association was with sponge gardens, which had the most distinct assemblage, and the greatest species richness and density of individuals. Habitat associations in fringe and barrens were less consistent. A substantial increase in the abundance of small individuals, coinciding with warmer sea temperatures, contributed to temporal fluctuations in the density of wrasses. Overall, habitats were not strongly partitioned among larger individuals of the most abundant species, suggesting that adults are largely habitat generalists whereas small, recruiting individuals showed greater habitat specialisation. The present study emphasises the importance of incorporating spatial, temporal and ontogenetic variability into surveys of fish assemblages to understand more fully the dynamics of temperate rocky-reef systems.
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Benincasa, Mario, Federico Falcini, Claudia Adduce, Gianmaria Sannino, and Rosalia Santoleri. "Synergy of Satellite Remote Sensing and Numerical Ocean Modelling for Coastal Geomorphology Diagnosis." Remote Sensing 11, no. 22 (November 12, 2019): 2636. http://dx.doi.org/10.3390/rs11222636.
Повний текст джерелаАнотація:
Sediment dynamics is the primary driver of the evolution of the coastal geomorphology and of the underwater shelf clinoforms. In this paper, we focus on mesoscale and sub-mesoscale processes, such as coastal currents and river plumes, and how they shape the sediment dynamics at regional or basin spatial scales. A new methodology is developed that combines observational data with numerical modelling: the aim is to pair satellite measurements of suspended sediment with velocity fields from numerical oceanographic models, to obtain an estimation of the sediment flux. A numerical divergence of this flux is then computed. The divergence field thus obtained shows how the aforementioned mesoscale processes distribute the sediments. The approach was applied and discussed on the Adriatic Sea, for the winter of 2012, using data provided by the ESA Coastcolour project and the output of a run of the MIT General Circulation Model.
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Filaretov, Vladimir, Dmitry Yukhimets, Aleksandr Zuev, and Alexey Zhirabok. "The development of AUV control system with accommodation to thruster faults." Robotics and Technical Cybernetics 9, no. 4 (December 30, 2022): 280–88. http://dx.doi.org/10.31776/rtcj.9405.
Повний текст джерелаАнотація:
Abstract A new method for the synthesis of AUV control system for high-precision and highly reliable spatial motion is proposed. The feature of these control systems is that they include an additional accommodation circuit that provides timely detection, determination of the magnitude and compensation for the consequences of the appearance of minor faults that occur in the AUV thrusters. The simulation results confirmed the efficiency and high quality of the synthesized systems. Key words Dynamics modeling of system of solids, unmanned underwater vehicle, UUV, AUUV, mobile robot, hyper-redundant robot, computer design of machines and mechanisms, SolidWorks Motion, MCS.ADAMS. Acknowledgements This work was supported by the Russian Foundation for Basic Research (projects 20-38-70161 and 19-08-00347).
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Medeiros, Paulo R., Ricardo S. Rosa, and Ronaldo B. Francini-Filho. "Dynamics of fish assemblages on a continuous rocky reef and adjacent unconsolidated habitats at Fernando de Noronha Archipelago, tropical western Atlantic." Neotropical Ichthyology 9, no. 4 (November 23, 2011): 869–79. http://dx.doi.org/10.1590/s1679-62252011005000048.
Повний текст джерелаАнотація:
In recent years, many studies investigated how density-dependent factors, such as shortages in microhabitat and food availability influence the structure of reef fish assemblages. Most of what is currently known, however, comes from comparisons of isolated patch reefs and from correlations between fish abundance and one or few microhabitat variables. In addition, most studies were done in the Caribbean and Indo-Pacific regions, whereas the South Atlantic region has been, to date, understudied. The present study evaluated spatial and temporal variations in reef fish abundance and species richness in a continuous rocky reef and adjacent unconsolidated habitats in a Southwestern Atlantic reef, using underwater techniques to assess both fish numbers and microhabitat variables (depth, rugosity, number of crevices and percent cover of live benthic organisms, bare rock, sand, and limestone). Higher species richness was observed at consolidated substratum stations on both sampling periods (May and October), but fish abundance did not show a significant spatial variation. Topographical complexity and percent cover of algae (except coralline algae) were amongst the most important determinants of species richness, and correlations between fish size and refuge crevice size were observed. The non-random patterns of spatial variation in species richness, and to a lesser extent, fish abundance, were related to differences in substratum characteristics and the inherent characteristics of fishes (i.e. habitat preferences) and not to geographical barriers restraining fish movement. This study highlights the importance of concomitantly assessing several microhabitat variables to determine their relative influence in reef fish assemblages.
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Lillis, Ashlee, Francesco Caruso, T. Aran Mooney, Joel Llopiz, DelWayne Bohnenstiehl, and David B. Eggleston. "Drifting hydrophones as an ecologically meaningful approach to underwater soundscape measurement in coastal benthic habitats." Journal of Ecoacoustics 2, no. 1 (February 6, 2018): 1. http://dx.doi.org/10.22261/jea.stbdh1.
Повний текст джерелаАнотація:
The ambient acoustic environment, or soundscape, is of broad interest in the study of marine ecosystems as both a source of rich sensory information to marine organisms and, more broadly, as a driver of the structure and function of marine communities. Increasing our understanding of how soundscapes affect and reflect ecological processes first requires appropriate characterization of the acoustic stimuli, and their patterns in space and time. Here, we present a novel method developed for measuring soundscape variation, using drifting acoustic recorders to quantify acoustic dynamics related to benthic habitat composition. Selected examples of drifter results from sub-tidal oyster-reef habitats in Pamlico Sound, North Carolina, USA, and from coral reef habitats in St. John, US Virgin Islands, highlight the efficacy and utility of this approach in quantifying soundscape variation in diverse habitats. The platform introduces minimal noise into the acoustic recordings, and allows sampling at spatial scales that might typically be overlooked using stationary hydrophone methods. We demonstrate that mobile hydrophone recording methods offer new insight into soundscape variation and provide a complementary approach to conventional passive acoustic monitoring techniques.
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Gomes, Sebastião Cícero Pinheiro, and Thiago Ávila Pouzada. "GERAÇÃO AUTOMÁTICA DE MODELOS DINÂMICOS DE CABOS." Ciência e Natura 39, no. 2 (May 23, 2017): 390. http://dx.doi.org/10.5902/2179460x22552.
Повний текст джерелаАнотація:
Dynamic modeling of cables is a research theme of great importance and practical application nowadays in the underwater oil industry. However, due to non-linearity behavior present on cable dynamics, as well as the need to work with many degrees of freedom, to develop dynamic models for these systems becomes a hard task. To develop dynamic models of cables, in this article is proposed a discrete formalism, which supposes the cable consisting of rigid links connected by fictitious elastic joints. The cables were considered with one of its endings articulated to a floating structure (ship or platform), while on the other ending were considered two cases: one free terminal loading; ending fixed to the ground. The cables are submersed and the hydrodynamic drag was considered from a simple model, proportional to the square of the relative velocity between the structure and the fluid. Using the Euler-Lagrange formalism, the dynamic models for cables considering two, three and four links were developed. From these models algorithms have been developed to automatically generate dynamic models for any number of links to represent in a discrete form the cable’s continuous flexibility. Simulations were performed, which showed the results agreeing qualitatively with the physical expected. A software has been developed to display animation from the spatial configuration of the cable. This animation, based on data from numerical simulation, allowed us show that the developed dynamic models give a great sense of physical reality.
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Gentil, Mathieu, Gaël Many, Xavier Durrieu de Madron, Pierre Cauchy, Ivane Pairaud, Pierre Testor, Romaric Verney, and François Bourrin. "Glider-Based Active Acoustic Monitoring of Currents and Turbidity in the Coastal Zone." Remote Sensing 12, no. 18 (September 4, 2020): 2875. http://dx.doi.org/10.3390/rs12182875.
Повний текст джерелаАнотація:
The recent integration of Acoustic Doppler Current Profilers (ADCPs) onto underwater gliders changes the way current and sediment dynamics in the coastal zone can be monitored. Their endurance and ability to measure in all weather conditions increases the probability of capturing sporadic meteorological events, such as storms and floods, which are key elements of sediment dynamics. We used a Slocum glider equipped with a CTD (Conductivity, Temperature, Depth), an optical payload, and an RDI 600 kHz phased array ADCP. Two deployments were carried out during two contrasting periods of the year in the Rhone River region of freshwater influence (ROFI). Coastal absolute currents were reconstructed using the shear method and bottom tracking measurements, and generally appear to be in geostrophic balance. The responses of the acoustic backscatter index and optical turbidity signals appear to be linked to changes of the particle size distribution in the water column. Significantly, this study shows the interest of using a glider-ADCP for coastal zone monitoring. However, the comparison between suspended particulate matter dynamics from satellites and gliders also suggests that a synoptic view of the processes involved requires a multiplatform approach, especially in systems with high spatial and temporal variability, such as the Rhone ROFI area.
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Bassett, Christopher, and Andone C. Lavery. "Echosounding in estuaries: Lessons learned from operations and data in four coastal systems." Journal of the Acoustical Society of America 151, no. 4 (April 2022): A149. http://dx.doi.org/10.1121/10.0010931.
Повний текст джерелаАнотація:
The properties and dynamics of estuarine environments often exhibit strong spatial gradients and rapidly evolving structure that can be difficult to sample and resolve. High-frequency acoustic backscattering techniques spanning from 10 s to 100 s of kilohertz are well-suited for estuarine studies given that they can provide synoptic imaging, aid in discriminating between sources of acoustic backscattering, and in some cases quantify variables of interest. Here, we compare acoustic backscattering measurements obtained using vessel-based, towed, and underwater vehicle operations from the Columbia River, Connecticut River, James River, and Mobile Bay. These data are supported by other oceanographic measurements and circulation models. The sources of backscattering observed across these sites include bubbles, turbulent microstructure, stratification, suspended sediment, and biology. We focus on the quantification of and discrimination between areas dominated by unique processes, in addition to lessons learned regarding frequency selection and operations in estuarine environments.
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Tousant, K. T. D., and S. Fai. "THE DIGITAL RESTITUTION OF LOT 3317: USING UNDERWATER IMAGE BASED MODELLING TO GENERATE VALUE IN VIRTUAL HERITAGE EXPERIENCES." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W10 (April 17, 2019): 189–95. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w10-189-2019.
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<p><strong>Abstract.</strong> The intent of this paper is to demonstrate the cultural value that Virtual Heritage experiences can generate. As a proof of concept, game resolution assets were optimized from high polygon image based models (IBMs) and rendered in real-time, within a Head Mounted Display (HMD). The case study of lot 3317 was chosen to facilitate heuristic explorations pertinent to the history of the St. Lawrence Seaway, Canada. This case study explores methods in creating and validating heritage values, while valourizing assets as a cultural resources for use in the future. While at the same time, challenging the current spatial dynamics by conceptually reducing the distance between the viewer and the flooded landscape. In addition to demonstrating the cultural values generated through the veneration of lot 3317, the paper aims to provide a model for optimizing and post processing meshes produced through Under-Water Image-Base Modelling.</p>
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Tousant, K. T. D., and S. Fai. "THE DIGITAL RESTITUTION OF LOT 3317: USING UNDERWATER IMAGE BASED MODELLING TO GENERATE VALUE IN VIRTUAL HERITAGE EXPERIENCES." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-2/W15 (August 26, 2019): 1163–70. http://dx.doi.org/10.5194/isprs-archives-xlii-2-w15-1163-2019.
Повний текст джерелаАнотація:
<p><strong>Abstract.</strong> The intent of this paper is to demonstrate the cultural value that Virtual Heritage experiences can generate. As a proof of concept, game resolution assets were optimized from high polygon image based models (IBMs) and rendered in real-time, within a Head Mounted Display (HMD). The case study of lot 3317 was chosen to facilitate heuristic explorations pertinent to the history of the St. Lawrence Seaway, Canada. This case study explores methods in creating and validating heritage values, while valourizing assets as a cultural resource for use in the future. While at the same time, challenging the current spatial dynamics by conceptually reducing the distance between the viewer and the flooded landscape. In addition to demonstrating the cultural values generated through the veneration of lot 3317, the paper aims to provide a model for optimizing and post processing meshes produced through Under-Water Image-Base Modelling.</p>
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Barott, Katie L., Beltran Rodriguez-Mueller, Merry Youle, Kristen L. Marhaver, Mark J. A. Vermeij, Jennifer E. Smith, and Forest L. Rohwer. "Microbial to reef scale interactions between the reef-building coral Montastraea annularis and benthic algae." Proceedings of the Royal Society B: Biological Sciences 279, no. 1733 (November 16, 2011): 1655–64. http://dx.doi.org/10.1098/rspb.2011.2155.
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Competition between reef-building corals and benthic algae is of key importance for reef dynamics. These interactions occur on many spatial scales, ranging from chemical to regional. Using microprobes, 16S rDNA pyrosequencing and underwater surveys, we examined the interactions between the reef-building coral Montastraea annularis and four types of benthic algae. The macroalgae Dictyota bartayresiana and Halimeda opuntia , as well as a mixed consortium of turf algae, caused hypoxia on the adjacent coral tissue. Turf algae were also associated with major shifts in the bacterial communities at the interaction zones, including more pathogens and virulence genes. In contrast to turf algae, interactions with crustose coralline algae (CCA) and M. annularis did not appear to be antagonistic at any scale. These zones were not hypoxic, the microbes were not pathogen-like and the abundance of coral–CCA interactions was positively correlated with per cent coral cover. We propose a model in which fleshy algae (i.e. some species of turf and fleshy macroalgae) alter benthic competition dynamics by stimulating bacterial respiration and promoting invasion of virulent bacteria on corals. This gives fleshy algae a competitive advantage over corals when human activities, such as overfishing and eutrophication, remove controls on algal abundance. Together, these results demonstrate the intricate connections and mechanisms that structure coral reefs.
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Forest, A., M. Babin, L. Stemmann, M. Picheral, M. Sampei, L. Fortier, Y. Gratton, et al. "Ecosystem function and particle flux dynamics across the Mackenzie Shelf (Beaufort Sea, Arctic Ocean): an integrative analysis of spatial variability and biophysical forcings." Biogeosciences Discussions 9, no. 8 (August 14, 2012): 10883–960. http://dx.doi.org/10.5194/bgd-9-10883-2012.
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Abstract. A better understanding of how environmental changes affect organic matter fluxes in Arctic marine ecosystems is sorely needed. Here, we combine mooring times-series, ship-based measurements and remote-sensing to assess the variability and forcing factors of vertical fluxes of particulate organic carbon (POC) across the Mackenzie Shelf in 2009. We developed a geospatial model of these fluxes to proceed to an integrative analysis of their biophysical determinants in summer. Flux data were obtained with sediment traps and via a regional empirical algorithm applied to particle size-distributions (17 classes from 0.08–4.2 mm) measured by an Underwater Vision Profiler 5. Redundancy analyses and forward selection of abiotic/biotic parameters, linear trends, and spatial structures (i.e. principal coordinates of neighbor matrices, PCNM), were conducted to partition the variation of POC flux size-classes. Flux variability was explained at 69.5 % by the addition of a linear temporal trend, 7 significant PCNM and 9 biophysical variables. The interaction of all these factors explained 27.8 % of the variability. The first PCNM canonical axis (44.4 % of spatial variance) reflected a shelf-basin gradient controlled by bottom depth and ice concentration (p < 0.01), but a complex assemblage of fine-to-broad scale patterns was also identified. Among biophysical parameters, bacterial production and northeasterly wind (upwelling-favorable) were the two strongest explanatory variables (r2 cum. = 0.37), suggesting that bacteria were associated with sinking material, which was itself partly linked to upwelling-induced productivity. The second most important spatial structure corresponded actually to the two areas where shelf break upwelling is known to occur under easterlies. Copepod biomass was negatively correlated (p < 0.05) with vertical POC fluxes, implying that metazoans played a significant role in the regulation of export fluxes. The low fractal dimension of settling particles (1.26) and the high contribution (~94 %) of fast-sinking small aggregates (<1 mm; 20–30 m d−1) to the mass fluxes suggested that settling material across the region was overall fluffy, porous, and likely resulting from the aggregation of marine detritus, gel-like substances and ballast minerals. Our study demonstrates that vertical POC fluxes in Arctic shelf systems are spatially complex, sensitive to environmental forcings, and determined by both physicochemical mechanisms and food web functioning. In conclusion, we hypothesize that the incorporation of terrestrial matter into the Beaufort Sea food web could be catalyzed by bacteria via the incorporation of dissolved terrestrial carbon liberated through the photo-cleavage and/or hydrolysis of land-derived POC interweaved with marine aggregates.
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Damar, Ario, Franciscus Colijn, Karl-Juergen Hesse, Luky Adrianto, Yonvitner, Achmad Fahrudin, Fery Kurniawan, et al. "Phytoplankton Biomass Dynamics in Tropical Coastal Waters of Jakarta Bay, Indonesia in the Period between 2001 and 2019." Journal of Marine Science and Engineering 8, no. 9 (September 1, 2020): 674. http://dx.doi.org/10.3390/jmse8090674.
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A study of nutrients, underwater light dynamics, and their correlation with phytoplankton biomass was conducted in the tropical estuary of Jakarta Bay, Indonesia, in the dry season during the period from 2001 to 2019. This study analyzed the spatial and temporal dynamics of phytoplankton biomass and its correlation with phytoplankton biomass. There was significant increase in nutrient concentration in Jakarta Bay, with annual means of 27.97 µM dissolved inorganic nitrogen (DIN) and 11.31 µM phosphates in 2001, increasing to 88.99 µM DIN and 25.92 µM phosphates in 2019. Increased mean nutrient concentrations were accompanied by increased mean phytoplankton biomass, from 15.81 µg Chl-a L−1 in 2001 to 21.31 µg Chl-a L−1 in 2019. The eutrophication status of Jakarta Bay waters was calculated using the Tropical Index for Marine Systems eutrophication index, which showed increased areas of hyper-eutrophic and eutrophic zones, while the mesotrophic area decreased. The hyper-eutrophic zone dominated the areas around river mouths and the inner part of the bay, while eutrophic status was observed in the middle part of the bay and mesotrophic status was found in the outer part of the bay. The area of hyper-eutrophic water increased 1.5-fold, from 75.1 km2 in 2001 to 114.0 km2 in 2019. Increasing eutrophication of the bay has had negative ecological consequences including algal blooms, hypoxic conditions, and mass mortality of marine biota, and it urgently requires remediation.
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Chen, Qiuwen, Yenory Morales-Chaves, Hong Li, and Arthur E. Mynett. "Hydroinformatics techniques in eco-environmental modelling and management." Journal of Hydroinformatics 8, no. 4 (December 1, 2006): 297–316. http://dx.doi.org/10.2166/hydro.2006.011.
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The high complexity of aquatic ecosystems and the multiple processes involved, make the development of ecohydraulics and eco-environmental models a challenging subject. Conventionally, computer-based models use a mathematical formulation for the processes involved which are then solved by numerical methods. These models are often derived based on the assumption of spatial homogeneity and conservation principles of mass, momentum and energy. Development of these models often demands a clear understanding of the processes involved. However, the above assumptions are easily violated when spatial heterogeneity, individual species behaviour and local interactions play a significant role in the system dynamics. In particular for eco-environmental systems, knowledge on local interactions that determine the overall system behaviour is not always available. Although the rapid advances of data-driven techniques have recently made great contributions to water-environment related research, data on ecosystems are often quite limited, which restricts the application of data mining methods to eco-environmental system modelling. In addition, no modelling – also not black-box modelling – can be undertaken without having at least some understanding of the basic processes and mechanisms involved. It is always advisable to start exploring any dataset using conventional statistical techniques, as elaborated in this paper for a case study on Western Xiamen Bay, China. Neural network trimming was then used to establish the dominant factors; it was shown that a relatively simple ANN model was quite capable of capturing the essential features, provided the right input parameters are chosen. Examples of integrated approaches to ecohydraulics modelling coupling formulations with cellular automata and physical equations with fuzzy rules are presented for applications on eutrophication modelling of Taihu Lake in China, competitive growths and colonization of two underwater macrophytes in Lake Veluwe in The Netherlands, and forecasting of algal blooms in the Dutch coastal waters on the North Sea. A mussel dynamics model developed for the Upper Mississippi River in the USA demonstrates the feasibility of individual based modelling in ecosystem dynamics. Numerical models are quite capable of simulating the abiotic aquatic environment, including complicated fluid flow and transport mechanisms. However, when it comes to simulating the biotic and ecosystem dynamics, the interaction of individual species with their environment, as well as the interactions amongst species, has to be taken into account. The future of ecohydraulics and eco-environmental modelling thus seems to lie in the integration of different paradigms and techniques, which is the core content of the hydroinformatics discipline.
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DAW, TIM M., JAN ROBINSON, and NICHOLAS A. J. GRAHAM. "Perceptions of trends in Seychelles artisanal trap fisheries: comparing catch monitoring, underwater visual census and fishers' knowledge." Environmental Conservation 38, no. 1 (February 22, 2011): 75–88. http://dx.doi.org/10.1017/s0376892910000901.
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SUMMARYFisheries scientists and managers are increasingly engaging with fishers’ knowledge (FK) to provide novel information and improve the legitimacy of fisheries governance. Disputes between the perceptions of fishers and scientists can generate conflicts for governance, but can also be a source of new perspectives or understandings. This paper compares artisanal trap fishers’ reported current catch rates with landings data and underwater visual census (UVC). Fishers’ reports of contemporary ‘normal’ catch per day tended to be higher than recent median landings records. However, fishers’ reports of ‘normal’ catch per trap were not significantly different from the median CPUE calculated from landings data, and reports of ‘good’ and ‘poor’ catch rates were indicative of variability observed in landings data. FK, landings and UVC data all gave different perspectives of trends over a ten-year period. Fishers’ perceptions indicated greater declines than statistical models fitted to landings data, while UVC evidence for trends varied between sites and according to the fish assemblage considered. Divergence in trend perceptions may have resulted from differences in the spatial, temporal or taxonomic focus of each dataset. Fishers may have experienced and understood behavioural changes and increased fishing power, which may have obscured declines from landings data. Various psychological factors affect memory and recall, and may have affected these memory-based estimates of trends, while different assumptions underlying the analysis of both interview data and conventional scientific data could also have led to qualitatively different trend perceptions. Differing perspectives from these three data sources illustrate both the potential for ‘cognitive conflicts’ between stakeholders who do not rely on the same data sources, as well as the importance of multiple information sources to understand dynamics of fisheries. Collaborative investigation of such divergence may facilitate learning and improve fisheries governance.
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Forest, A., M. Babin, L. Stemmann, M. Picheral, M. Sampei, L. Fortier, Y. Gratton, et al. "Ecosystem function and particle flux dynamics across the Mackenzie Shelf (Beaufort Sea, Arctic Ocean): an integrative analysis of spatial variability and biophysical forcings." Biogeosciences 10, no. 5 (May 2, 2013): 2833–66. http://dx.doi.org/10.5194/bg-10-2833-2013.
Повний текст джерелаАнотація:
Abstract. A better understanding of how environmental changes affect organic matter fluxes in Arctic marine ecosystems is sorely needed. Here we combine mooring times series, ship-based measurements and remote sensing to assess the variability and forcing factors of vertical fluxes of particulate organic carbon (POC) across the Mackenzie Shelf in 2009. We developed a geospatial model of these fluxes to proceed to an integrative analysis of their determinants in summer. Flux data were obtained with sediment traps moored around 125 m and via a regional empirical algorithm applied to particle size distributions (17 classes from 0.08–4.2 mm) measured by an Underwater Vision Profiler 5. The low fractal dimension (i.e., porous, fluffy particles) derived from the algorithm (1.26 ± 0.34) and the dominance (~ 77%) of rapidly sinking small aggregates (< 0.5 mm) in total fluxes suggested that settling material was the product of recent aggregation processes between marine detritus, gel-like substances, and ballast minerals. Modeled settling velocity of small and large aggregates was, respectively, higher and lower than in previous studies within which a high fractal dimension (i.e., more compact particles) was consequential of deep-trap collection (~400–1300 m). Redundancy analyses and forward selection of abiotic/biotic parameters, linear trends, and spatial structures (i.e., principal coordinates of neighbor matrices, PCNM) were conducted to partition the variation of the 17 POC flux size classes. Flux variability was explained at 69.5% by the addition of a temporal trend, 7 significant PCNM, and 9 biophysical variables. The first PCNM canonical axis (44.5% of spatial variance) reflected the total magnitude of POC fluxes through a shelf-basin gradient controlled by bottom depth and sea ice concentration (p < 0.01). The second most important spatial structure (5.0%) corresponded to areas where shelf break upwelling is known to occur under easterlies and where phytoplankton was dominated by diatoms. Among biophysical parameters, bacterial production and northeasterly wind (upwelling-favorable) were the two strongest corollaries of POC fluxes (r2 cum. = 0.37). Bacteria were correlated with small aggregates, while northeasterly wind was associated with large size classes (> 1 mm ESD), but these two factors were weakly related with each other. Copepod biomass was overall negatively correlated (p < 0.05) with vertical POC fluxes, implying that metazoans acted as regulators of export fluxes, even if their role was minor given that our study spanned the onset of diapause. Our results demonstrate that on interior Arctic shelves where productivity is low in mid-summer, localized upwelling zones (nutrient enrichment) may result in the formation of large filamentous phytoaggregates that are not substantially retained by copepod and bacterial communities.
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Jentzen, Anna, Joachim Schönfeld, Agnes K. M. Weiner, Manuel F. G. Weinkauf, Dirk Nürnberg, and Michal Kučera. "Seasonal and interannual variability in population dynamics of planktic foraminifers off Puerto Rico (Caribbean Sea)." Journal of Micropalaeontology 38, no. 2 (December 20, 2019): 231–47. http://dx.doi.org/10.5194/jm-38-231-2019.
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Abstract. The state of a population of planktic foraminifers at a certain time reflects multiple processes in the upper ocean, including environmental conditions to which the population was exposed during its growth, the age of the cohorts, and spatiotemporal patchiness. We carried out depth-stratified (0–60, 60–100 m) replicated sampling off Puerto Rico in autumn 2012, revisiting three stations previously sampled in autumn 1994 and spring 1995, in order to analyze seasonal and interannual variability of planktic foraminifers and the stable isotopic composition of their tests. The merged dataset from all three sampling campaigns allows us to assess short- and long-term changes in foraminiferal population dynamics and the spatial assemblage coherency along the shelf edge. All three sample series cover more than 2 weeks during either spring (1995) or autumn (1994, 2012) and include the time of the full moon when reproduction of some surface-dwelling planktic foraminifers has been postulated to take place. Our analyses indicate that interannual variability affected the faunal composition, and both autumn assemblages were characterized by oligotrophic tropical species, dominated by Trilobatus sacculifer and Globigerinoides ruber (white and pink variety). However, G. ruber (white) had a higher abundance in 1994 (37 %) than in 2012 (3.5 %), which may be partially due to increasing sea surface temperatures since the 1990s. Between 60 and 100 m water depth, a different faunal composition with a specific stable oxygen isotope signature provides evidence for the presence of the Subtropical Underwater at the sampling site. Measurements on T. sacculifer sampled in autumn 2012 revealed that test size, calcification and incidence of sac-like chambers continued to increase after full moon, and thus no relation to the synodic lunar reproduction cycle was recognized. During autumn 2012, outer bands of hurricane Sandy passed the Greater Antilles and likely affected the foraminifers. Lower standing stocks of living planktic foraminifers and lower stable carbon isotope values from individuals collected in the mixed layer likely indicate the response to increased rainfall and turbidity in the wake of the hurricane.
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Rakhmatullina, Irina R., Zagir Z. Rakhmatullin, and Alexey Yu Kulagin. "Remote monitoring of green plants of Ufa in 1988-2018." RUDN Journal of Ecology and Life Safety 28, no. 3 (December 15, 2020): 263–74. http://dx.doi.org/10.22363/2313-2310-2020-28-3-263-274.
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Green spaces of the city are an integral part of its ecological framework. When planning urban space, information is needed on their actual distribution, condition and dynamics. To do this, it is advisable to use satellite images. The purpose of the work is to conduct remote monitoring of green spaces of Ufa using Landsat satellite images over the past 30 years. Image processing, including radiometric calibration, reducing the amount of data from 6 channels to 3 main components, uncontrolled classification of images, grouping classes to 5 types of underlying surface (open soil, no vegetation, grassy vegetation, tree and shrub vegetation, underwater), matrix construction changes were made using the tools of the SAGA GIS software product. As a result, a map was constructed showing spatial changes of the tree-shrub vegetation type over 30 years. The plots on which this type is preserved make up 16 073 ha, on which it was replaced by another type of underlying surface - 3700 ha. Plots characterized in 1988 by other types, and in 2018 converted to the tree-shrub vegetation type, occupy 8665 ha. On the one hand, there is a positive trend in the conservation and increase in the area of tree-shrub plantings. But this is not characteristic of the entire urban district, but mainly of the forests of the Ufa urban forestry, which are located mainly on the outskirts, around the central part of the city. For intracity tree-shrub plantings that are not related to the forest fund and located in the built-up part of the city, stable negative dynamics and a change in other types of underlying surface are characteristic.
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Velichko, S., A. Matveev, D. Bychkov, V. Ivanov, V. Tsymbal, and O. Gavrilenko. "Radar monitoring of long surface waves in the pacific ocean." RADIOFIZIKA I ELEKTRONIKA 26, no. 1 (2021): 3–11. http://dx.doi.org/10.15407/rej2021.01.003.
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Subject and Purpose. The paper addresses interaction processes going in the ocean–atmosphere system and is concerned with their research by the method of radar remote sensing. Specifically, the matter of concern is the detection and parameter estimation of long waves, including nonlinear ones, on the ocean surface. Methods and Methodology. In August 1988, a series of successive radar surveys of long surface wave manifestations on the Pacific Ocean surface was carried out in the 3 cm wave range by means of an airborne X-band radar system “Analog”. The analysis of the results includes estimation of both spatial and frequency features of the detected long-wave packets and, also, a comparison of the measurement results with model calculations performed in the framework of theory of radio wave scattering by the sea surface in the presence of seismic wave effects. Results. Radar images of wave packets of long surface waves in the open ocean have been obtained. From the imaging data, the spatial scale (5…10 km) of these waves, the lengths (1…5 km) of wave packet components and the wave packet velocity (6.1 m/s) have been derived. Analysis has been given to the nonlinear form of wave packet components, and their amplitudes have been estimated by comparing the experimental and theoretically obtained radio contrasts. The bathymetry of the surface-wave track has been performed to suggest that the observed wave packet represents a set of solitons generated by a seismic impact with the further underwater collapse. Conclusions. A possibility has been demonstrated for monitoring wave packets of long surface waves in their propagation dynamics. The experiments of the sort for gaining a deeper insight into the ocean–atmosphere interaction physics can be conducted by means of not only airborne but also spaceborne radar systems with allowance made for the rate of surveys in both time and space.
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Shakir’yanov, M. M. "Review of research solid mechanics laboratory for 2020–2022." Multiphase Systems 17, no. 1-2 (2022): 62–72. http://dx.doi.org/10.21662/mfs2022.1.006.
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The article presents an overview of the research of the Laboratory of Solid Mechanics IMech UFRS RAS for 2020-2022. All studies were published as articles (there are two exceptions in the list of references, registered in the Register of Computer Programs) in well-known domestic and (or) foreign scientific journals on mechanics. During the three years under consideration, a number of new problems of aerohydroelasticity were solved and important results were obtained on the dynamic behavior of thin-walled structural elements interacting with external and internal continuous media. In particular, the linear bending of a cantilever rod loaded with all-round pressure and longitudinal force is considered in static and dynamic formulations. The areas of attraction of the deflection to the upper and lower equilibrium positions of a two-support pipe during its spatial bending-rotational vibrations are determined. The interaction of forced and parametric vibrations of the pipeline has been studied. The influence of the internal and external added masses of continuous media on the frequency of natural vibrations of a pipe moving with acceleration in the transverse direction is studied. The eigenfrequencies of bending vibrations of a micro- and nanometer-sized rod clamped at the ends are calculated. From the solution of the inverse problem for the changed values of natural frequencies, the coordinate and magnitude of the added mass are found. Linear oscillations of micro- and nanostrings are also considered when the pressure in a gaseous medium changes, taking into account surface effects. Using a model of molecular dynamics with a reduced number of degrees of freedom, the eigenfrequencies of bending vibrations of carbon nanotubes (CNTs) of different diameters are calculated under conditions of a plane-deformed state. In addition, part of the work was devoted to the study of the phenomenon of the ascent of an underwater gas pipeline and the determination of its buoyancy parameters. The scientific articles presented in this review are arranged in chronological order. For all articles, their summary is given and the main conclusions are formulated.
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Grossmann, V., D. Nakath, M. Urlaub, N. Oppelt, R. Koch, and K. Köser. "DIGITAL TWINNING IN THE OCEAN – CHALLENGES IN MULTIMODAL SENSING AND MULTISCALE FUSION BASED ON FAITHFUL VISUAL MODELS." ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences V-4-2022 (May 18, 2022): 345–52. http://dx.doi.org/10.5194/isprs-annals-v-4-2022-345-2022.
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Abstract. In engineering, machines are typically built after a careful conception and design process: All components of a system, their roles and the interaction between them is well understood, and often even digital models of the system exist before the actual hardware is built. This enables simulations and even feedback loops between the real-world system and a digital model, leading to a digital twin that allows better testing, prediction and understanding of complex effects. On the contrary, in Earth sciences, and particularly in ocean sciences, models exist only for certain aspects of the real world, of certain processes and of some interactions and dependencies between different “components” of the ocean. These individual models cover large temporal (seconds to millions of years) and spatial (millimetres to thousands of kilometres) scales, a variety of field data underpin them, and their results are represented in many different ways. A key to enabling digital twins in the oceans is fusion at different levels, in particular, fusion of data sources and modalities, fusion over different scales and fusion of differing representations. We outline these challenges and exemplify different envisioned digital twins employed in the oceans involving remote sensing, underwater photogrammetry and computer vision, focusing on optical aspects of the digital twinning process. In particular, we look at the holistic sensing scenarios of optical properties in coastal waters as well as seafloor dynamics at volcanic slopes and discuss road blockers for digital twins as well as potential solutions to increase and widen the use of digital twins.
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Khasanah, Kadir, and Jompa. "Reproductive Biology of Three Important Threatened/Near-Threatened Groupers (Plectropomus leopardus, Epinephelus polyphekadion and Plectropomus areolatus) in Eastern Indonesia and Implications for Management." Animals 9, no. 9 (September 2, 2019): 643. http://dx.doi.org/10.3390/ani9090643.
Повний текст джерелаАнотація:
The three grouper species most heavily fished for the live reef fish trade (LRFT) in Indonesia are Plectopomus leopardus (greatest catch volume), and two species classified as Vulnerable on the International Union for Conservation of Nature (IUCN) Red List: Plectropomus areolatus and Epinephelus polyphekadion. Understanding the reproductive biology of these fishes is essential for sustainable management, but relevant data are limited. This study aimed to determine reproductive dynamics, so as to inform management measures to maintain the reproductive capacity of these groupers. Grouper gonad samples collected from fish caught for the LRFT were analyzed histologically. Data were also collected from participatory mapping and interviews with fishermen, and underwater monitoring of three known spawning aggregation sites in the Wakatobi National Park, Eastern Indonesia. Based on observed gonad development, the respective lengths and weights at first maturity were: 37.7 cm and 759 g (P. leopardus); 36.65 cm and 771.2 g (P. areolatus); 36.95 cm and 889.9 g (E. polyphekadion). The mean weight of the groupers market-based sampled was higher than the size at first sexual maturity. Sex transition was observed in P. leopardus; sex reversal was not observed in E. polyphekadion, and the sex pattern of P. areolatus was unresolved. Based on the fisher surveys and spawning aggregation monitoring, spawning occurs around the new moon from September to April, with reproductive peaks in November and December. Fisheries management measures that are suggested to sustain grouper stocks include enforcing appropriate size limits, temporal spatial closures (spawning aggregation sites), and a trading ban during the peak spawning season (November–December).
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Moline, Mark A., Shelley M. Blackwell, Chris von Alt, Ben Allen, Thomas Austin, James Case, Ned Forrester, Robert Goldsborough, Mike Purcell, and Roger Stokey. "Remote Environmental Monitoring Units: An Autonomous Vehicle for Characterizing Coastal Environments*." Journal of Atmospheric and Oceanic Technology 22, no. 11 (November 1, 2005): 1797–808. http://dx.doi.org/10.1175/jtech1809.1.
Повний текст джерелаАнотація:
Abstract In oceanography, there has been a growing emphasis on coastal regions, partially because of their inherent complexity, as well as the increasing acknowledgment of anthropogenic impacts. To improve understanding and characterization of coastal dynamics, there has been significant effort devoted to the development of autonomous systems that sample the ocean on relevant scales. Autonomous underwater vehicles (AUVs) are especially well suited for studies of the coastal ocean because they are able to provide near-synoptic spatial observations. These sampling platforms are beginning to transition from the engineering groups that developed and continue to improve them to the science user. With this transition comes novel applications of these vehicles to address new questions in coastal oceanography. Here, the relatively mature Remote Environmental Monitoring Units (REMUS) AUV system is described and assessed. Analysis of data, based on 37 missions and nearly 800 km of in-water operation, shows that the vehicle’s navigational error estimates were consistently less than 10 m, and error estimates of mission duration, distance, velocity, and power usage, once the vehicle was properly ballasted, were below 10%. An example of the transition to science is demonstrated in an experiment conducted in 2002 in Monterey Bay, California, where the vehicle was used to quantify critical horizontal length scales of variability. Length scales on the order of tens to hundreds of meters were found for the region within 25 km of the coastline, which has significant implications for designing proper sampling approaches and parameterizing model domains. Results also demonstrate the overall utility of the REMUS vehicle for use by coastal oceanographers.
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Nie, Yunli, Dalei Song, Zhenyu Wang, Yan Huang, and Hua Yang. "Design and Motion Performance Analysis of Turbulent AUV Measuring Platform." Sensors 22, no. 2 (January 8, 2022): 460. http://dx.doi.org/10.3390/s22020460.
Повний текст джерелаАнотація:
The use of a multi-functional autonomous underwater vehicle (AUV) as a platform for making turbulence measurements in the ocean is developed. The layout optimization of the turbulence package and platform motion performance are limitation problems in turbulent AUV design. In this study, the computational fluid dynamics (CFD) method has been used to determine the optimized layout position and distance of the shear probe integrated into an AUV. When placed 0.8 D ahead of the AUV nose along the axis, the shear probe is not influenced by flow distortion and can contact the water body first. To analyze the motion of the turbulence AUV, the dynamic model of turbulence AUV for planar flight is obtained. Then, the mathematical equations of speed and angle of attack under steady-state motion have also been obtained. By calculating the hydrodynamic coefficients of the turbulence AUV and given system parameters, the simulation analysis has been conducted. The simulation results demonstrated that the speed of turbulent AUV is 0.5–1 m/s, and the maximum angle of attack is less than 6.5°, which meets the observation requirements of the shear probe. In addition, turbulence AUV conducted a series of sea-trials in the northern South China Sea to illustrate the validity of the design and measurement. Two continuous profiles (1000 m) with a horizontal distance of 10 km were completed, and numerous high-quality spatiotemporal turbulence data were obtained. These profiles demonstrate the superior flight performance of turbulence AUV. Analysis shows that the measured data are of high quality, with the shear spectra being in very good agreement with the Nasmyth spectrum. Dissipation rates are consistent with background shear. When shear velocity is weak, the measurement of dissipation rate is 10−10 W Kg−1. All indications are that the turbulence AUV is suitable for long-term, contiguous ocean microstructure measurements, which will provide data needed to understand the temporal and spatial variability of the turbulent processes in the oceans.
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Cai, Lei, Yuejun Li, Chuang Chen, and Haojie Chai. "Dynamic Multiscale Feature Fusion Method for Underwater Target Recognition." Journal of Sensors 2022 (July 21, 2022): 1–10. http://dx.doi.org/10.1155/2022/8110695.
Повний текст джерелаАнотація:
The feature information of small-scale targets is seriously missing under the interference of complex underwater terrain and light refraction. Moreover, the unbalanced distribution of underwater target samples can also affect the accuracy of spatial semantic feature extraction. Aiming at the above problems, this paper proposes a dynamic multiscale feature fusion method for underwater target recognition. Firstly, this paper uses multiscale info noise contrastive estimation (MS-InfoNCE) loss to extract the significant features of the target at 4 scales. Secondly, the method learns the spatial semantic features of the target through a dynamic conditional probability matrix. Finally, this paper designs different feature fusion mechanisms for different scale targets, dynamically fusing multiscale significant features and spatial semantic features to recognize underwater weak targets. The experimental results show that the recognition accuracy of the proposed algorithm is 1.38% higher than that of the existing algorithm when recognizing underwater distorted targets.
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Piepenburg, Dieter, Alexander Buschmann, Amelie Driemel, Hannes Grobe, Julian Gutt, Stefanie Schumacher, Alexandra Segelken-Voigt, and Rainer Sieger. "Seabed images from Southern Ocean shelf regions off the northern Antarctic Peninsula and in the southeastern Weddell Sea." Earth System Science Data 9, no. 2 (July 21, 2017): 461–69. http://dx.doi.org/10.5194/essd-9-461-2017.
Повний текст джерелаАнотація:
Abstract. Recent advances in underwater imaging technology allow for the gathering of invaluable scientific information on seafloor ecosystems, such as direct in situ views of seabed habitats and quantitative data on the composition, diversity, abundance, and distribution of epibenthic fauna. The imaging approach has been extensively used within the research project DynAMo (Dynamics of Antarctic Marine Shelf Ecosystems) at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research Bremerhaven (AWI), which aimed to comparatively assess the pace and quality of the dynamics of Southern Ocean benthos. Within this framework, epibenthic spatial distribution patterns have been comparatively investigated in two regions in the Atlantic sector of the Southern Ocean: the shelf areas off the northern tip of the Antarctic Peninsula, representing a region with above-average warming of surface waters and sea-ice reduction, and the shelves of the eastern Weddell Sea as an example of a stable high-Antarctic marine environment that is not (yet) affected by climate change. The AWI Ocean Floor Observation System (OFOS) was used to collect seabed imagery during two cruises of the German research vessel Polarstern, ANT-XXIX/3 (PS81) to the Antarctic Peninsula from January to March 2013 and ANT-XXXI/2 (PS96) to the Weddell Sea from December 2015 to February 2016. Here, we report on the image and data collections gathered during these cruises. During PS81, OFOS was successfully deployed at a total of 31 stations at water depths between 29 and 784 m. At most stations, series of 500 to 530 pictures ( > 15 000 in total, each depicting a seabed area of approximately 3.45 m2 or 2.3 × 1.5 m) were taken along transects approximately 3.7 km in length. During PS96, OFOS was used at a total of 13 stations at water depths between 200 and 754 m, yielding series of 110 to 293 photos (2670 in total) along transects 0.9 to 2.6 km in length. All seabed images taken during the two cruises, including metadata, are available from the data publisher PANGAEA via the two persistent identifiers at https://doi.org/10.1594/PANGAEA.872719 (for PS81) and https://doi.org/10.1594/PANGAEA.862097 (for PS96).
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Su, Yishan, Lijie Dong, and Qiuling Yang. "DCN-MAC: A Dynamic Channel Negotiation MAC Mechanism for Underwater Acoustic Sensor Networks." Sensors 20, no. 2 (January 10, 2020): 406. http://dx.doi.org/10.3390/s20020406.
Повний текст джерелаАнотація:
In the design of media access control (MAC) mechanism in underwater acoustic sensor networks (UASNs), due to the propagation characteristic of low-speed underwater acoustic signals, it is necessary to solve the spatial–temporal uncertainty problem. In order to avoid the multi-user access conflict in underwater networks, reduce the energy cost and improve the throughput and fairness across the network, a dynamic channel negotiation MAC mechanism based on spatial–temporal mapping of receiving queue (DCN-MAC) was proposed. DCN-MAC uses a duty cycle mechanism and implements a network management based on dynamic single node wake-up. The awakening node collects the request to send (RTS) and network status information in the network to solve the problem of space-temporal uncertainty and the highly dynamic needs of network access nodes and access services. The simulation results show that in different network scenarios, especially in those featuring high density and heavy network load, compared with the traditional underwater acoustic network MAC protocols, this protocol can effectively improve the network throughput and reduce the packet loss probability caused by multi-node conflict.
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Dudakova, Dina, Vladimir Anokhin, Mikhail Dudakov, and Andrey Ronzhin. "On Theoretical Foundations of Aerolimnology: Study of Fresh Water Bodies and Coastal Territories Using Air Robot Equipment." Informatics and Automation 21, no. 6 (November 24, 2022): 1359–93. http://dx.doi.org/10.15622/ia.21.6.10.
Повний текст джерелаАнотація:
The integration of the methodological basis of several different sciences in interdisciplinary research is a characteristic feature of new mechanisms for solving modern applied problems. The emerging theoretical foundations of aerolimnology, as a new scientific direction, are considered from the point of view of the contribution of three key sciences to it: limnology, informatics and robotics. Classifications of methods and approaches of limnological research, airborne robotic means, and information technologies that are promising for solving problems in the field of aerolimnology are given. The task of the scientific direction of aerolimnology is formulated as the study of the possibilities and limitations of combined methods of remote sensory measurement, robotic sampling and analytical study of the parameters of freshwater ecosystems to monitor and predict the dynamics of their development. Among the main areas of aerolimnological research, the following are distinguished: the construction of orthophotomaps and photogrammetric spatial models of the bottom topography and individual elements of the bottom landscape and coastal zone of various scales; geological and geophysical mapping of the underwater part of the coastal zone; the study of phytoplankton, in particular, the "bloom" of water caused by cyanobacteria; study of distribution and migration of large representatives of hydrofauna; study of temperature fields and processes of redistribution of water masses. The limitations imposed on the use of unmanned aerial vehicles (UAVs) in sampling and monitoring coastal water areas are discussed, primarily weather-climatic, temporal, spatial, and technical. The advantage of using unmanned aerial vehicles in aerolimnology is justified by an increase in the speed of data acquisition, the possibility of approaching hard-to-reach and territorially remote objects, and a decrease in the influence of the human factor. The scientific novelty of the presented research consists in an attempt to integrate interdisciplinary knowledge when using unmanned aerial vehicles and processing the obtained data based on artificial intelligence technologies in the study of limnological objects and processes. The important role of geoinformation systems is noted and examples of maps of shore typification and geomorphology of Lake Ladoga are given, posted on the website of the Center for the Collective Use of Scientific Equipment "North-Western Center for Monitoring and Forecasting the Development of Territories" of the St. Petersburg Federal Research Center of the Russian Academy of Sciences. The main stages of the methodology for conducting aerolimnological studies using interdisciplinary approaches based on limnology, informatics and robotic tools operating in different environments are considered.
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Cai, Lei, Chuang Chen, and Haojie Chai. "Underwater Distortion Target Recognition Network (UDTRNet) via Enhanced Image Features." Computational Intelligence and Neuroscience 2021 (October 22, 2021): 1–10. http://dx.doi.org/10.1155/2021/4193625.
Повний текст джерелаАнотація:
It is difficult for the autonomous underwater vehicle (AUV) to recognize targets similar to the environment in lacking data labels. Moreover, the complex underwater environment and the refraction of light cause the AUV to be unable to extract the complete significant features of the target. In response to the above problems, this paper proposes an underwater distortion target recognition network (UDTRNet) that can enhance image features. Firstly, this paper extracts the significant features of the image by minimizing the info noise contrastive estimation (InfoNCE) loss. Secondly, this paper constructs the dynamic correlation matrix to capture the spatial semantic relationship of the target and uses the matrix to extract spatial semantic features. Finally, this paper fuses the significant features and spatial semantic features of the target and trains the target recognition model through cross-entropy loss. The experimental results show that the mean average precision (mAP) of the algorithm in this paper increases by 1.52% in recognizing underwater blurred images.
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Filaretov, V. F., and D. A. Yukhimets. "Two-Loop System with Reference Model for Control of Spatial Movement of Cargo Underwater Vehicle." Mekhatronika, Avtomatizatsiya, Upravlenie 22, no. 3 (March 2, 2021): 134–44. http://dx.doi.org/10.17587/mau.22.134-144.
Повний текст джерелаАнотація:
Currently, autonomous underwater vehicles (AUV) are increasingly used to perform tasks related to the maintenance of underwater communications and various underwater production complexes, as well as performing underwater technological operations. To effectively perform these operations, AUV must have high-quality control systems that will ensure their accurate movement both along long spatial trajectories formed during their movement to the objects of work, and when performing complex maneuvers near underwater infrastructure objects. At the same time, the main difficulty that arises in the process of synthesis of AUV control systems is the significant non-linearity of the dynamic models of these control objects, the presence of interactions between their degrees of freedom, as well as the uncertainty and variability of their parameters. In this paper, we propose a method for synthesizing the spatial motion control system of the AUV, which allows us to take into account these negative effects. This system contains two loops. The first loop includes a combined system containing a nonlinear controller to achieve the desired dynamic characteristics of the AUV, when its parameters are equal to the nominal values, and a controller with self-tuning according to the reference model, which provides compensation for an unknown or variable part of the parameters. In this case, the parameters of the controller with the reference model are selected to reduce the possible amplitude of the discontinuous signal for controlling the AUV velocity. The second loop is a non-linear position controller that allows to take into account the dynamic properties of the velocity control loop and the kinematic properties of the AUV. The advantage of the proposed control system in comparison with traditional ones based on PID controllers is a higher control accuracy when moving along complex spatial trajectories, regardless of changes in the AUV parameters. The simulation results confirmed the high efficiency of the synthesized two-loop control system.
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Huang, Bo, Zhongyan Liu, Yujing Xu, Qiaochu Ding, Mengchun Pan, Jiafei Hu, and Qi Zhang. "Characteristics of Magnetic Fields Induced by the Wake of an Underwater Vehicle." Applied Sciences 12, no. 16 (August 9, 2022): 7964. http://dx.doi.org/10.3390/app12167964.
Повний текст джерелаАнотація:
Underwater vehicles generate hydrodynamic wakes within a large area that last for a longtime during navigation, thus generating induced magnetic fields, and these are of great significance for detecting and tracking underwater vehicles. In combination with the wakefield and magnetic field simulations, this study adopts the dynamic overlapping mesh technology to conduct a numerical simulation of the wake magnetic field during the movement of an underwater vehicle. This paper introduces the causes of formation and laws of evolution of the wake magnetic field, analyzes its spatial distribution and time-domain changes, and discusses the time-frequency domain characteristics at different monitoring points as well as the effects of navigation speed and acceleration on wake magnetic fields. Our results indicate that the wake magnetic field of an underwater vehicle belongs to a low-frequency weak signal of 0–5 Hz; as the navigation speed increases, the barycenter frequency of the wake magnetic field decreases and the half-energy bandwidth increases. The increase in acceleration of the underwater vehicle will cause a higher growth rate of the wake magnetic field. This paper provides a theoretical reference for the detection of underwater vehicles based on wake magnetic fields.
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Lebedev, Alexander. "Methods of Discontinuous Control for the Autonomous Underwater Vehicles." Applied Mechanics and Materials 278-280 (January 2013): 1473–76. http://dx.doi.org/10.4028/www.scientific.net/amm.278-280.1473.
Повний текст джерелаАнотація:
New methods of the synthesis of multi-dimensional robust and adaptive control systems for the centralized control of the spatial motion of autonomous underwater vehicles (AUV) is developed in this paper, such as variable structure system (VSS) and self-adjustment system with reference model. The conditions of the sliding mode existence and the self-adjustment process stability with the presence of essential dynamic reciprocal effect between all control channels are obtained and strictly proved. The application of synthesized discontinuous control provides the high control quality at any variations of the object parameters within the given ranges.
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Haulsee, Danielle E., Matthew W. Breece, Dewayne A. Fox, and Matthew J. Oliver. "Simple is sometimes better: a test of the transferability of species distribution models." ICES Journal of Marine Science 77, no. 5 (April 7, 2020): 1752–61. http://dx.doi.org/10.1093/icesjms/fsaa024.
Повний текст джерелаАнотація:
Abstract Species distribution models (SDMs) are often empirically developed on spatially and temporally biased samples and then applied over much larger spatial scales to test ecological hypotheses or to inform management. Underlying this approach is the assumption that the statistical relationships between species observations and environmental predictors are applicable to other locations and times. However, testing and quantifying the transferability of these models to new locations and times can be a challenge for resource managers because of the technical difficulty in obtaining species observations in new locations in a dynamic environment. Here, we apply two SDMs developed in the Mid-Atlantic Bight for Atlantic sturgeon (Acipenser oxyrhynchus oxyrhynchus) to the South Atlantic Bight and use an autonomous underwater vehicle to test model predictions. We compare Atlantic sturgeon occurrence to two SDMs: one associating sturgeon occurrence with simple seascapes and one developed through coupling occurrences with environmental predictors in a generalized additive mixed model (GAMM). Our analysis showed that the seascape model was transferable across these disparate regions; however, the complex GAMM was not. The association of the imperilled Atlantic sturgeon with simple seascapes allows managers to easily integrate this remotely sensed dynamic oceanographic product into future ecosystem-based management strategies.
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de Lima, Rui L. Pedroso, Floris C. Boogaard, and Rutger E. de Graaf-van Dinther. "Innovative Water Quality and Ecology Monitoring Using Underwater Unmanned Vehicles: Field Applications, Challenges and Feedback from Water Managers." Water 12, no. 4 (April 23, 2020): 1196. http://dx.doi.org/10.3390/w12041196.
Повний текст джерелаАнотація:
With climate change and urban development, water systems are changing faster than ever. Currently, the ecological status of water systems is still judged based on single point measurements, without taking into account the spatial and temporal variability of water quality and ecology. There is a need for better and more dynamic monitoring methods and technologies. Aquatic drones are becoming accessible and intuitive tools that may have an important role in water management. This paper describes the outcomes, field experiences and feedback gathered from the use of underwater drones equipped with sensors and video cameras in various pilot applications in The Netherlands, in collaboration with local water managers. It was observed that, in many situations, the use of underwater drones allows one to obtain information that would be costly and even impossible to obtain with other methods and provides a unique combination of three-dimensional data and underwater footage/images. From data collected with drones, it was possible to map different areas with contrasting vegetation, to establish connections between fauna/flora species and local water quality conditions, or to observe variations of water quality parameters with water depth. This study identifies opportunities for the application of this technology, discusses their limitations and obstacles, and proposes recommendation guidelines for new technical designs.
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Grekov, A. N., S. Y. Alekseev, and V. Y. Bashkirov. "The results of laboratory tests underwater navigation system for environmental monitoring devices." Monitoring systems of environment, no. 3 (September 24, 2020): 65–74. http://dx.doi.org/10.33075/2220-5861-2020-3-65-74.
Повний текст джерелаАнотація:
An urgent task facing the developers of unmanned underwater vehicles (UUVs) (autonomous underwater vehicles, remotely operated underwater vehicles) is to improve the accuracy of determining the output navigation parameters: orientation angles, linear velocities and location coordinates. The systems for determining the course and attitude position (Attitude and Heading Reference Systems – AHRS) and spatial positioning systems, which are supposed to equip the UUV, should not be expensive, but technologically suitable for mass production with acceptable coordinate determination accuracy. At the first stage of the research, a prototype of the navigation platform with software for it was developed and manufactured, on which experimental data from the measuring channels were obtained in laboratory conditions, and then their preliminary processing was carried out. The analysis of existing methods for increasing the accuracy of determining the output navigation parameters of unmanned underwater vehicles showed that, despite their dynamic development and constant improvement, the error in calculating coordinates when using MEMS sensors remains high and unstable. The use of an additional hydrostatic tilt unit in the navigation platform will make it possible to compensate for the errors of MEMS sensors, which require constant correction during their stable operation, unfortunately, only for a short period of time. The analysis of typical errors of MEMS sensors is carried out. The deterministic part of the error of these sensors can be eliminated by calibration, and to estimate the stochastic errors, we used the Allan variation. The obtained error values will be used in the future to form the Kalman filter of the resulting system.