Search Results (194)

Deep-sea mining systems are a critical pathway for acquiring key strategic resources such as nickel and cobalt. The core conveying component, the mining rigid pipe, is susceptible to transverse vibrations under complex wave excitation, which threaten system safety, necessitating the development of efficient and reliable vibration control solutions. This paper proposes an improved Triple-spring nonlinear energy sink (TS-NES). An integrated dynamic model coupling the mining rigid pipe and the TS-NES is established using the vector form intrinsic finite element method and solved via the central difference method. The effectiveness and superiority of the TS-NES are verified through displacement, time–frequency, energy, and phase analyses. Subsequently, a systematic parameter sensitivity study is conducted. The results indicate that under both single-frequency and multi-frequency wave excitations, the TS-NES exhibits broadband, high-efficiency vibration suppression performance superior to that of the conventional tuned mass damper (TMD). It can substantially and uniformly dissipate vibration energy and maintain an approximately 90° phase lag with the primary structure. Parameter studies reveal that installing the TS-NES in the upper section of the pipe yields significant vibration reduction. The device is insensitive to stiffness variations, and appropriately increasing its mass, damping, and inclination angle can further enhance the vibration suppression effect. Full article

Deep-sea mining operations demand continuous, drift-free positioning over multi-day missions—a requirement that traditional acoustic dead-reckoning systems struggle to meet due to cumulative error accumulation and frequent DVL bottom-lock loss in sediment plume environments. Inspired by Google Cartographer’s 2D grid mapping paradigm, we present a prior map-based visual localization framework that decouples offline mapping from real-time localization, fundamentally eliminating drift through absolute image registration against pre-built seabed mosaics. By integrating adaptive keyframe selection, Multi-Scale Retinex (MSR) enhancement, and the AD-LG deep feature matching architecture, our system constructs globally consistent seabed maps for absolute positioning. The framework leverages deformable convolutions and LightGlue to effectively mitigate challenges such as low texture and non-rigid distortion. Quantitative validation on tank simulation datasets demonstrates significant superiority over IMU-only and standard fusion schemes; qualitative deployment on real Pacific CCZ imagery confirms near-real-time operational feasibility on an embedded Jetson Orin NX platform. This system establishes visual navigation as a viable backup to acoustic systems, addressing a critical gap in deep-sea mining vehicle autonomy. Full article

The Rio Grande Rise (RGR) is the largest oceanic plateau in the South Atlantic and represents a key natural laboratory for understanding oceanic plateau formation, deep-sea circulation, ecosystem functioning, and ferromanganese crust development. This study presents a critical synthesis of current scientific knowledge on the RGR, integrating geological, geophysical, oceanographic, biological, and geochemical evidence published over the last two decades. Geophysical data reveal a complex tectono-magmatic evolution involving Late Cretaceous plume-related volcanism, crustal thickening, rifting, and subsequent subsidence. The structural framework of the plateau is dominated by the Cruzeiro do Sul Rift, which plays a central role in controlling sedimentation, magmatism, and seawater circulation. Oceanographic studies demonstrate that the interaction between the southern branch of the South Equatorial Current and the complex topography of the RGR generates intense internal tides and bottom currents, strongly influencing sediment transport and benthic habitats. Biological investigations indicate that the RGR hosts diverse deep-sea communities, including sponge grounds, cold-water corals, and associated fauna, whose distribution is tightly linked to geomorphology and hydrodynamics. Ferromanganese crusts occurring on the plateau preserve valuable geochemical records of oceanographic and redox conditions, although their spatial distribution, thickness, and metal budgets remain incompletely constrained. Despite major advances, significant knowledge gaps persist regarding crustal structure, sedimentary evolution, ecosystem functioning, and mineral formation processes. This review highlights these uncertainties and outlines research priorities necessary to improve understanding of oceanic plateaus and deep-sea systems in the South Atlantic. Full article

Sediment plumes generated by seafloor mining vehicles represent a major environmental concern in polymetallic nodule harvesting operations. This study investigates plume dispersion induced by sediment disturbances during mining using numerical simulations based on the similarity principle. A representative mining region is modeled, and the motion of mining vehicles is simulated to define the sediment disturbance source. The simulations employ the experimentally validated P-T Euler model (Particle–Turbulence Interaction Euler model) to examine the effects of sediment release velocity and ambient current velocity on plume dispersion characteristics. The results show that increasing the sediment release velocity primarily enhances the initial turbidity flux and significantly expands the plume core diffusion range, indicating that mining disturbances dominate near-field plume behavior. In contrast, the ambient current velocity strongly controls plume morphology and transport, promoting upward transport, long-range advection, and enhanced turbulent dissipation that governs far-field dispersion. Overall, plume diffusion is initially controlled by mining-induced sediment release but becomes increasingly dominated by ambient flow during large-scale transport. These findings provide a theoretical basis for predicting sediment plume behavior and assessing potential environmental impacts in deep-sea mining areas. Full article

The transport mechanism of non-spherical particles in complex pipelines, such as right-angle elbows, remains insufficiently understood, posing challenges to the efficiency optimization of industrial systems like deep-sea mining. This study investigates the fundamental mechanisms governing the upward transport of 1–15 mm non-spherical particles in a 100 mm right-angle bend by integrating Particle Image Velocimetry (PIV) experiments with coupled computational fluid dynamics and discrete element method (CFD-DEM) simulations. We systematically quantify the effects of key factors—flow velocity, particle size distribution, and shape factor (ranging from 0.4 to 1)—on flow asymmetry, particle dynamics, and transport efficiency. The results reveal a pronounced flow asymmetry, where the outer-side peak velocity is approximately twice that of the inner side, accompanied by a persistent separation vortex. Crucially, transport efficiency is governed by particle interactions: wide-grading blends achieve up to 12% higher conveying speed than narrow fractions at high flow rates. While spherical particles (shape factor, SF = 1) attain the highest axial velocity, particles with SF ≥ 0.8 are identified as optimal, maintaining moderate rotation, concentrating in the central high-speed zone, and thereby combining high transport velocity with minimal wall contact. These findings elucidate the underlying particle–fluid interactions in bends and provide a quantitative basis for optimizing particle morphology in industrial hydraulic transport systems. Full article

Gravity currents constrained by bottom walls are prevalent in engineering applications such as industrial discharges and deep-sea mining, and will pose significant environmental risks. In this study, the influence of jet source parameters on the dynamics and diffusion characteristics of particle-driven bottom currents was investigated through physical experiments using Digital Image Processing (DIP). This non-invasive technology is cost-effective and exhibits broad applicability. The results demonstrated that the downstream plume front $d_{\mathrm{L}\mathrm{m}\mathrm{a}\mathrm{x}}$, the maximum lift height $h_{\mathrm{L}\mathrm{m}\mathrm{a}\mathrm{x}}$ and the average lift height $h_{\mathrm{a}\mathrm{v}\mathrm{e}}$ all exhibit a decreasing trend with increasing Richardson number (Ri) after impingement, and show a linear increase with rising Reynolds number (Re). The plume diffusion scale S follows a two-stage evolution: during the inertia-dominated stage, S evolves exponentially over time t as $S=a{e}^{bt}$, while in the equilibrium stage of negative buoyancy and turbulent dissipation, S follows a power-law relationship $S=a{t}^b$ (b < 1). The rate of change of S increases with smaller jet angles α, and the variations with dimensionless bottom clearance H/D remain within 10%. The dimensionless average longitudinal expansion rate ${\displaystyle \frac{\overline{E}}{\sqrt{g\prime /D}}}$ reaches minimum values at α = 75°, peaks at H/D = 10, and exhibits a linear decreasing trend with Ri. As Re increases, ${\displaystyle \frac{\overline{E}}{\sqrt{g\prime /D}}}$ displays a three-stage fluctuating behavior. This study provides valuable experimental data that improve the understanding of gravity current behavior under wall confinement and support the predictive modelling of gravity current. Full article

The optimization of enrichment zones for Co-rich crusts involves multiple factors such as crust thickness, elemental content, topography, slope, and biological distribution, making it a complicated research endeavor. Based on survey data from the contract area, the present study pioneers the integration of environmental factors into enrichment zone selection. It conducts a comprehensive analysis of resource, environment, and mining considerations, alongside optimization methodologies. Quantitative indicators for resource, environment, and mining are spatially correlated and assigned to corresponding grid cells. A weighted scoring method is proposed to compare enrichment zone selection results under different weightings, finally forming the optimal enrichment zone selection scheme. This scheme fully achieves the maximization of resource reserves, the protection of biological communities, and the safeguarding of future mineral development. It also provides technical reference for enrichment zone selection of deep-sea minerals such as polymetallic nodules and hydrothermal sulphides. Full article

Future shortages of minerals essential for green technologies have driven the search for new supply sources. In this context, deep-sea mining (DSM) has emerged as an innovative alternative for accessing strategic metals such as manganese and cobalt, among others, through the exploitation of deposits including polymetallic nodules, ferromanganese crusts, and seafloor massive sulfides. However, while DSM could help meet the growing demand for minerals, it also presents significant challenges and opportunities. This study compiles and analyzes scientific publications on DSM to assess its potential effects. It reviews the main environmental impacts and, in addition, proposes a systematic classification of them. It also addresses the social and economic effects associated with this activity, considering human dynamics and the factors that shape its long-term viability. The results indicate that, although DSM may offer advantages over terrestrial mining, it still lacks a robust framework to mitigate impacts and anticipate future consequences. Unlike previous reviews focused on partial dimensions of sustainability, this work integrates environmental, social, and economic dimensions through a systematic impact classification. Critical challenges remain in ecological understanding, environmental monitoring, and long-term socio-economic assessment, alongside an international governance framework that is still nascent, reinforcing the need for interdisciplinary research. Full article

The complex seabed topography and mechanical properties of deep-sea sediments impose stringent requirements on the traction performance and locomotion stability of tracked mining vehicles. Experimental investigations on the coupled effects of grouser geometry and operating conditions on traction remain limited. To address this, rheological tests and multi-parameter traction experiments were conducted. Deep-sea sediments were modeled as a power-law fluid to capture their non-Newtonian behavior, considering particle size distribution, water content, and compaction state. Using a self-designed traction test apparatus, the influences of grouser geometry and operating parameters on traction force were systematically analyzed. Results indicate that both grouser configuration and operating conditions significantly affect traction force magnitude and stability. Rectangular grousers, exhibiting more uniform stress distribution and pronounced shear bands, demonstrated enhanced traction efficiency and locomotion stability under high-load, low-speed conditions. When the grouser length was 30 mm and the traveling speed was maintained at 7–12 mm/s, sediment fluidization was significantly mitigated, improving traction performance. Furthermore, a spacing of at least 20 mm between adjacent grousers produced a synergistic effect, increasing sediment shear strength by approximately 30–40%. These findings provide quantitative guidance for grouser design and operational optimization of tracked deep-sea mining vehicles. Full article

In deep-sea mining operations, the seabed sediments (mud and sand) are very soft and slippery. This often causes tracked vehicles to slip and veer off course when they are driving on the seafloor. To solve the path-tracking problem for deep-sea mining vehicles, this study suggests a path-tracking controller that can adapt to the seabed environment. Firstly, it is necessary to establish a kinematic and dynamic model of the mining vehicle’s motion, analysing its seabed slippage and force application. The system has been developed on the basis of the Stanley algorithm and utilises a two-degree-of-freedom kinematic model, with lateral deviation and heading deviation acting as inputs. The establishment of fuzzy rules to adjust the gain parameter K enables the mining vehicle to adaptively modify its gain parameters according to the seabed environment and path. Secondly, a fuzzy PID controller is established and optimised to address the limitation that fuzzy PID control rules are constrained by the designer’s experience. At the same time, a relationship was established between how fast the drive wheel accelerates and the slip rate based on the dynamic model. This stops the drive wheel from slipping by limiting how fast it can go. Finally, a mechanical model of the mining vehicle was created in Recurdyn and a system model was developed in MATLAB/Simulink for joint simulation analysis. The simulation results demonstrate the efficacy of the proposed control strategy, establishing it as a reliable method for tracking the path of subsea mining vehicles. Full article

To enhance the autonomous operation capability of deep-sea mining vehicle formations, this study addresses the issues of slow convergence in formation path planning and insufficient obstacle avoidance flexibility under complex environments by investigating a global path planning and local obstacle avoidance strategy based on an improved RRT algorithm*. Through dynamic elliptical sampling, adaptive goal-biased sampling, safe distance detection, and path smoothing optimization, the efficiency and passability of path planning are improved. For the obstacle avoidance of formation members, a priority determination model incorporating local obstacle avoidance, formation contraction, and transformation is designed, and methods such as Gaussian distribution fan-shaped sampling and trajectory backtracking are proposed to optimize the local planning effect. Simulation results show that this method can effectively improve the path planning quality and obstacle avoidance performance of mining vehicle formations in complex environments. Specifically, when in a longitudinal formation, the maximum inter-vehicle error is approximately 15.1%, and the average error is controlled within 3.5%; when in a triangular formation, the maximum inter-vehicle error is approximately 20%, and the average error is controlled within 4.2%, indicating promising application prospects. Full article

Seabed mining has gained widespread attention under the blue economy concept, offering economic opportunities while posing significant environmental risks. In Sri Lanka, where mining of seabed resources is growing, understanding public perceptions and preferences for seabed conservation remain crucial to ensure sustainable resource management. This study, therefore, represents the first empirical assessment of public preference and Willingness to Pay (WTP) for seabed conservation in Sri Lanka. A Discrete Choice Experiment (DCE)-based approach was employed to assess public preferences for seabed conservation. Data were collected from 630 respondents across Sri Lanka using a pre-tested self-administered structured survey. The analysis employed Conditional Logit (CL) and Random Parameter Logit (RPL) models to estimate preference heterogeneity and attribute trade-offs. The findings of the study reported strong public support, with a WTP of Sri Lankan Rupees (LKR) 3532 per household per year for seabed conservation. Younger, well-educated individuals demonstrated a significantly higher preference for seabed conservation. Biodiversity loss (66.9%), physical damage to seabed (40.7%) and exploitation of natural resources (17.8%) were recognized as major consequences of sea bed mining, highlighting the need for stringent regulatory frameworks (34%) and public engagement (44%) in sustainable seabed conservation. The RPL model revealed significant preference heterogeneity for key attributes. A significant positive preference for a 30% reduction in mineral extraction (coefficient = 0.894, p < 0.05) reinforces public preference for stricter extraction limits. A 25% reduction for biodiversity and habitat destruction (coefficient = 0.010, p < 0.05) reflects public concern for seabed conservation in the context of ongoing marine resource related economic development activities. These results underscore the importance of integrating economic valuation into seabed conservation policies, ensuring that seabed mining activities align with sustainability goals. The study suggests targeted awareness campaigns, financial incentives, and inclusive policymaking to bridge socio-economic disparities and foster long-term public support for seabed conservation. These insights provide a critical foundation for policymakers to develop balanced approaches that promote economic benefits, while safeguarding marine ecosystems within Sri Lanka’s blue economy framework. Full article

Mining bioactive secondary metabolites from microorganisms originating from deep-sea cold seep holds significant potential for discovering novel drug lead compounds. In this study, three known indole derivatives (1–3) were isolated from cold-seep-derived Halomonas meridiana OUCLQ22-B7. Subsequently, two-new indole dimers, meribisindole A (4) and meribisindole B (5), with nine known metabolites (6–14) were obtained via indole precursor feeding strategy. The structure of these compounds was elucidated via a combination of spectroscopic methods and circular dichroism (CD) measurement. Antimicrobial assays revealed that compounds 4, 7 and 8 exhibited potent inhibitory activity against Fusarium oxysporum CICC 41029 with minimal inhibitory concentrations (MICs) of 0.39−12.5 μg/mL, and compound 11 showed significant growth inhibition against Staphylococcus aureus CCARM 3090 with MIC value at 0.098 μg/mL. Full article

The prediction of deep-sea mining sediment plumes is essential for assessing and mitigating the environmental impacts on vulnerable deep-sea ecosystems. In this paper, the numerical simulation method is adopted to predict the sediment plume transportation. Fluid dynamics are governed by the incompressible Navier–Stokes equations, coupled with the Standard k–ε turbulence model to capture turbulent diffusion. The air–water free surface is tracked by a high-resolution Volume of Fluid (VOF) method. The pressure–velocity coupling utilizes the PISO algorithm. Sediment transport is governed by the advection–diffusion equation. The mathematical model is validated through experiments. There is a good consistency between the experiment results and the numerical results, which proves that the numerical method can be applied. The study calculates the diffusion range and characteristics of plumes under different free stream velocities, injection velocities and discharge densities. The results indicate that an increase in free stream velocity enhances the development of turbulence, but conversely restricts the expansion of the mixing zone between the plume and the ambient water. A greater injection velocity leads to a wider distribution range of the plume, while inhibiting the development of local turbulence. A higher plume discharge density results in a larger horizontal distribution range, while hindering the effective mixing between the plume and the ambient water body. Full article

In view of the requirements and characteristics of a deep-sea polymetallic nodule collector’s movements according to a planned path and speed during operation, a collector trajectory tracking system scheme based on virtual target vehicle reference is proposed. In this system, the virtual target vehicle moves according to the planned path and speed, thereby generating a dynamic target path and speed. A fuzzy controller calculates the collector’s angular-velocity command based on the lateral position deviation and the heading-angle deviation between the collector and the target vehicle, and a proportional controller calculates the collector’s body linear velocity control command based on the longitudinal position deviation between the collector and the target vehicle. By integrating these two commands, the collector tracks the target vehicle and thereby realizes trajectory tracking of the planned path and speed. A control system is designed, and simulation studies are carried out. The results show that the designed system enables the collector to track the planned path and speed well under operational conditions. The trajectory tracking method based on virtual target vehicle reference can also form an organic integration of path planning and trajectory tracking, generate dynamic planned paths and speeds for the entire mining area, and realize movement of the collector along the planned path and speed throughout the whole operation. Full article