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  • 1
    Online Resource
    Online Resource
    MDPI AG ; 2023
    In:  Journal of Marine Science and Engineering Vol. 11, No. 2 ( 2023-02-04), p. 349-
    In: Journal of Marine Science and Engineering, MDPI AG, Vol. 11, No. 2 ( 2023-02-04), p. 349-
    Abstract: To date, hydraulic collection is the most widely considered technology in polymetallic-nodule mining, since there is no direct contact between hydraulic collectors and ocean floor. To construct a hydraulic collector that results in the least sediment disturbance, it is critical to develop an insightful understanding of the interaction between the collector and sediment bed. To this end, we conducted a set of small-scale experiments in which several operational conditions were tested, delivering the first quantitative data for sediment erosion resulting from a hydraulic collector driving over a sand bed. This paper presents and discusses the experimental results and observations. It is found that the collector’s forward velocity is inversely proportional to the bed-sediment erosion depth, since the bed is exposed to the flow for a longer time when the collector drives slower and vice versa. In contrast, an increased jet velocity leads to a larger erosion depth. Furthermore, when the collector underside is nearer to the sediment bed, a larger sediment layer is exposed to the water flow, resulting in a larger erosion depth. Finally, the experimental results show that collector water jets strike the sediment bed under an inclined angle, destabilizing the upper sediment layer and consequently dragging sediment particles along toward the collection duct and behind the collector head. This study improves the predictability of sediment erosion created by Coandă-effect-based collectors, which is a crucial asset to optimize the collector design and decrease the extent of the associated sediment plumes.
    Type of Medium: Online Resource
    ISSN: 2077-1312
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2738390-8
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  • 2
    Online Resource
    Online Resource
    Elsevier BV ; 2023
    In:  Ocean Engineering Vol. 277 ( 2023-06), p. 114250-
    In: Ocean Engineering, Elsevier BV, Vol. 277 ( 2023-06), p. 114250-
    Type of Medium: Online Resource
    ISSN: 0029-8018
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2023
    detail.hit.zdb_id: 1498543-3
    detail.hit.zdb_id: 160791-1
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  • 3
    In: Systems Engineering, Wiley
    Abstract: In this paper, model‐based systems engineering (MBSE) and discrete event simulation (DES) are combined to assess the performance of an offshore production system at an early stage. Various systems engineering tools are applied to an industrial case concerning the retrieval of deep‐sea minerals, and a simulation engine is developed to calculate the annual production output. A mean production of 1 Million tonnes of ore per year is estimated for an operation in the Norwegian Sea using Monte Carlo simulation. Depending on the limiting design wave height of the marine operations, the estimated production output ranges from 280,000 tonnes to 1.8 Million tonnes per year. The constrained parameter of the production system is particularly the wave height operational limit of the ship‐to‐ship transfer operation. We present the learning outcome from applying MBSE and DES to this case and discuss important aspects for improved performance.
    Type of Medium: Online Resource
    ISSN: 1098-1241 , 1520-6858
    Language: English
    Publisher: Wiley
    Publication Date: 2023
    detail.hit.zdb_id: 2017742-2
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  • 4
    Online Resource
    Online Resource
    Elsevier BV ; 2023
    In:  Results in Engineering Vol. 17 ( 2023-03), p. 100852-
    In: Results in Engineering, Elsevier BV, Vol. 17 ( 2023-03), p. 100852-
    Type of Medium: Online Resource
    ISSN: 2590-1230
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2023
    detail.hit.zdb_id: 2972369-3
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  • 5
    Online Resource
    Online Resource
    MDPI AG ; 2022
    In:  Sensors Vol. 22, No. 8 ( 2022-04-07), p. 2833-
    In: Sensors, MDPI AG, Vol. 22, No. 8 ( 2022-04-07), p. 2833-
    Abstract: We present a computationally efficient algorithm for using variations in the ambient magnetic field to compensate for position drift in integrated odometry measurements (dead-reckoning estimates) through simultaneous localization and mapping (SLAM). When the magnetic field map is represented with a reduced-rank Gaussian process (GP) using Laplace basis functions defined in a cubical domain, analytic expressions of the gradient of the learned magnetic field become available. An existing approach for magnetic field SLAM with reduced-rank GP regression uses a Rao-Blackwellized particle filter (RBPF). For each incoming measurement, training of the magnetic field map using an RBPF has a computational complexity per time step of O(NpNm2), where Np is the number of particles, and Nm is the number of basis functions used to approximate the Gaussian process. Contrary to the existing particle filter-based approach, we propose applying an extended Kalman filter based on the gradients of our learned magnetic field map for simultaneous localization and mapping. Our proposed algorithm only requires training a single map. It, therefore, has a computational complexity at each time step of O(Nm2). We demonstrate the workings of the extended Kalman filter for magnetic field SLAM on an open-source data set from a foot-mounted sensor and magnetic field measurements collected onboard a model ship in an indoor pool. We observe that the drift compensating abilities of our algorithm are comparable to what has previously been demonstrated for magnetic field SLAM with an RBPF.
    Type of Medium: Online Resource
    ISSN: 1424-8220
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2052857-7
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  • 6
    Online Resource
    Online Resource
    MDPI AG ; 2022
    In:  Minerals Vol. 12, No. 2 ( 2022-01-25), p. 139-
    In: Minerals, MDPI AG, Vol. 12, No. 2 ( 2022-01-25), p. 139-
    Abstract: Sliding wear of bulk handling equipment (e.g., shovel bucket, mill and transfer chute) can be dramatically reduced by using a convex pattern surface compared to a flat surface, by adjusting the flow behavior of particles moving along the convex pattern surface. To study the effect of particle size relative to the dimensions of the convex pattern surface, a coarse graining technique is applied. Comparisons of bulk flow and wear behavior between the convex pattern and flat surfaces illustrate the two-sided effect of the convex pattern surface on sliding wear. The bulk flow behavior indicates that the particle size has a minor effect on the velocity and angular velocity of particles for the flat surface, while it has a significant effect on those of the convex pattern surface. The wear results show that the particle size has negligible influence on the sliding wear of a flat surface and a linear relationship with the sliding wear of the convex pattern surface. The convex pattern surface can reduce the sliding wear through influencing the flow behavior of the bulk material when the equivalent radius of the convex is larger than r50 of particles. This research reveals the relationship between the dimensions of the convex pattern and the particle size on the sliding wear caused by the interaction between bulk material and bulk handling equipment. The relationship should be carefully considered for the applications of the convex pattern surface to bulk handling equipment.
    Type of Medium: Online Resource
    ISSN: 2075-163X
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2655947-X
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  • 7
    Online Resource
    Online Resource
    Frontiers Media SA ; 2022
    In:  Frontiers in Earth Science Vol. 10 ( 2022-5-19)
    In: Frontiers in Earth Science, Frontiers Media SA, Vol. 10 ( 2022-5-19)
    Abstract: Over the past decade, deep-sea mining (DSM) has received renewed interest due to scarcity of raw materials. Deep-sea mining has been spurred by the need for critical resources to support growing populations, urbanization, high-tech applications and the development of a green energy economy. Nevertheless, an improved understanding of how mining activities will affect the deep-sea environment is required to obtain more accurate assessment of the potential environmental impact. In that regard, the sediment plumes that are generated by the mining activity have received the highest concern, as these plumes might travel for several kilometers distance from the mining activity. Various plume sources are identified, of which the most profound are those generated by the excavation and collection process of the seafloor mining tool and the discharge flow to be released from the surface operation vessel after initial dewatering of the ore. In this review, we explore the physical processes that govern plume dispersion phenomena (focusing in the main on benthic plumes), discuss the state of the art in plume dispersion analysis and highlight what lessons can be learned from shallow water applications, such as dredging, to better predict and reduce the spread and impact of deep-sea mining plumes.
    Type of Medium: Online Resource
    ISSN: 2296-6463
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2741235-0
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  • 8
    Online Resource
    Online Resource
    Elsevier BV ; 2023
    In:  Powder Technology Vol. 415 ( 2023-02), p. 118109-
    In: Powder Technology, Elsevier BV, Vol. 415 ( 2023-02), p. 118109-
    Type of Medium: Online Resource
    ISSN: 0032-5910
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2023
    detail.hit.zdb_id: 2019938-7
    detail.hit.zdb_id: 208997-X
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  • 9
    Online Resource
    Online Resource
    MDPI AG ; 2022
    In:  Minerals Vol. 12, No. 5 ( 2022-04-29), p. 558-
    In: Minerals, MDPI AG, Vol. 12, No. 5 ( 2022-04-29), p. 558-
    Abstract: Renewable energy installations and energy storage solutions require significant quantities of critical raw materials such as nickel, cobalt and rare earth metals. The supply chains of these raw materials face many difficulties, such as the continuous decrease of mineral ore grades on land. In view of these complications, the motivation to search for new resources has grown, with the deep sea being seen as a potential source of these minerals. Polymetallic nodule mining generates turbidity currents, which could negatively impact the deep-sea environment. For that reason, we investigate this type of current experimentally and numerically in order to characterize the generated turbidity current. Various non-cohesive sediment types, i.e., different particle sizes, and different concentrations are tested using a lock-exchange set-up. Three sediment types (glass beads, silica sand and a 50/50 blend of glass beads and silica sand) with seven initial sediment concentrations are examined. Additionally, for the numerical work, a drift–flux modelling approach is used to simulate the performed lock-exchange experiments. The results show that the front velocities of the currents resulting from the three sediment types increases with increasing initial concentrations inside the lock regardless. Moreover, using the same initial concentration, the difference in front velocities between the generated currents of the three sediment types decreases as the initial concentration increases. When using an initial volumetric concentration of 2.5% and 3%, the difference in front velocities between the generated current of the three sediment types vanishes. Finally, by comparing the numerical and experimental results, the drift–flux model is proven to be a reliable numerical model for predicting the current.
    Type of Medium: Online Resource
    ISSN: 2075-163X
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2655947-X
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  • 10
    Online Resource
    Online Resource
    Elsevier BV ; 2020
    In:  Powder Technology Vol. 369 ( 2020-06), p. 72-87
    In: Powder Technology, Elsevier BV, Vol. 369 ( 2020-06), p. 72-87
    Type of Medium: Online Resource
    ISSN: 0032-5910
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2020
    detail.hit.zdb_id: 2019938-7
    detail.hit.zdb_id: 208997-X
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