Hasil untuk "Naval Science"

Xiangxu Meng, Xin Liu, Yinan Xu et al.

Accurate acoustic identification of marine mammals is vital for monitoring ocean health and human impacts. Existing methods often struggle with limited single-feature representations or suboptimal fusion of multiple features. This paper proposes an Evaluation-Adaptive Weighted Multi-Head Fusion Network that integrates CQT and STFT features via a dual-branch ResNet architecture. The model enhances intra-branch features using channel attention and adaptive weighting of each branch based on its validation accuracy during training. Experiments on the Watkins Marine Mammal Sound Database show that the proposed method achieves superior performance, reaching 96.05% accuracy and outperforming baseline and attention-based fusion models. This approach offers an effective solution for multi-feature acoustic recognition in complex underwater environments.

Feng MA, Xiumin WANG, Chen CHEN et al.

Objective Current ship navigation decision-making systems struggle to demonstrate superior performance in undefined sailing scenarios. Given the broad applicability of large language models （LLMs） in unknown scenarios, this study proposes a dual-LLM-core-driven adaptive ship navigation agent architecture （Nav-DLLC） to address this issue.MethodNav-DLLC employs ReAct-based prompting to decompose complex navigation tasks into manageable subtasks and invoke external tools for information collection, reducing LLM errors. Subsequently, a small-parameter LLM fine-tuned with low-rank adaptation （LoRA） serves as the collision avoidance core, processing unstructured data to generate COLREG-compliant decisions. ResultsSimulation experiments show that Nav-DLLC achieves outstanding performance in both traditional ship collision avoidance tasks and unstructured dynamic scenarios. Its collision avoidance accuracy is 86%, and its behavior compliance rate is 90%, significantly outperforming LLM baselines and traditional methods such as the Dynamic Window Approach （DWA） and Artificial Potential Field （APF）. The decision core's single-decision latency is 11.13 seconds, higher than the 0.73 seconds of traditional methods, yet still within the safe time window for collision avoidance decision-making. ConclusionNav-DLLC bridges the gap between traditional navigation systems and LLM technology, providing a safe and efficient intelligent decision-making paradigm for complex navigation environments and promoting the intelligent development of ship navigation.

Qikun Shen, Peng Zhang, Wenming Yu et al.

This study examines the potential distribution of Mackerel scad (<i>Decapterus macarellus</i>) in the South China Sea under future climate scenarios (SSP 1.26, SSP 2.45, SSP 5.85) using an ensemble species distribution model (SDM). Key environmental variables included sea surface salinity (SSS), sea surface height (SSH), sea surface temperature (SST), mixed-layer depth (MLD), chlorophyll-a concentration (CHL), and sea-bottom temperature (SBT). Results show that SST and MLD are the primary drivers of habitat suitability, with current suitable habitats concentrated in the northern offshore areas. Projections for the 2050s and 2090s indicate a reduction in suitable habitats, particularly under high-emission scenarios, with more gradual reductions under low-emission scenarios. Habitat loss is most pronounced in the northern South China Sea, while the central region is projected to see an expansion of suitable habitats. These findings highlight the climate impact on <i>D. macarellus</i> distribution and inform sustainable management strategies for the species in the region.

Irit Ittner, Anna‐Katharina Hornidge

This study analyses marine governance and knowledge politics of sediments in the Borkum Reef Ground from a historical and German perspective, as well as in the context of litigation against marine gas production from transboundary Dutch and German fields. The authors analysed interview transcripts, project documents, environmental media campaigns, and notes originating from participant observation and stakeholder engagement. The study employs the science and technology and sociology of ignorance approaches. It asks which implications for biodiversity protection and ocean governance derive from administrative fragmentation and knowledge politics by a diverse set of actors. National divisions and prioritised knowledge production led to a shift in perception of the area from a transboundary seabed habitat to two distinct national marine areas and resulted in a fragmented Schutzgebietskulisse including marine protected areas, restoration zones, and unprotected zones. The study illustrates how the prioritisation of mapping marine protected areas may backfire on knowledge gain in potential industrial zones and overall marine protection.

Weimin Yuan, Lixin Dai, Hua Feng et al.

The Einstein Probe (EP) is an interdisciplinary mission of time-domain and X-ray astronomy. Equipped with a wide-field lobster-eye X-ray focusing imager, EP will discover cosmic X-ray transients and monitor the X-ray variability of known sources in 0.5-4 keV, at a combination of detecting sensitivity and cadence that is not accessible to the previous and current wide-field monitoring missions. EP can perform quick characterisation of transients or outbursts with a Wolter-I X-ray telescope onboard. In this paper, the science objectives of the Einstein Probe mission are presented. EP is expected to enlarge the sample of previously known or predicted but rare types of transients with a wide range of timescales. Among them, fast extragalactic transients will be surveyed systematically in soft X-rays, which include γ-ray bursts and their variants, supernova shock breakouts, and the predicted X-ray transients associated with binary neutron star mergers. EP will detect X-ray tidal disruption events and outbursts from active galactic nuclei, possibly at an early phase of the flares for some. EP will monitor the variability and outbursts of X-rays from white dwarfs, neutron stars and black holes in our and neighbouring galaxies at flux levels fainter than those detectable by the current instruments, and is expected to discover new objects. A large sample of stellar X-ray flares will also be detected and characterised. In the era of multi-messenger astronomy, EP has the potential of detecting the possible X-ray counterparts of gravitational wave events, neutrino sources, and ultra-high energy γ-ray and cosmic ray sources. EP is expected to help advance the studies of extreme objects/phenomena and their underlying physical processes revealed in the dynamic X-ray universe, as well as studies in other areas of X-ray astronomy.

Gennadi Malaschonok, Roman Sakh

The article provides a brief description of the MathPartner service. This freely available cloud-based Mathematics is a universal system for symbolic-numeric calculations. Its Mathpar language is a subset of the LaTeX language, but allows you to create mathematical texts that contain "computable" mathematical operators. This opens up completely new opportunities for improving the educational process for all natural science disciplines, for the use of mathematics in scientific and engineering calculations. To save and freely exchange educational and other texts in the Mathpar language, a GitHub repository has been created. It is concluded that cloud mathematics MathPartner is a new breakthrough technology for school and university natural science education, for scientific and engineering applications.

Naval Kishore Mehta, Arvind, Shyam Sunder Prasad et al.

Monitoring complex assembly processes is critical for maintaining productivity and ensuring compliance with assembly standards. However, variability in human actions and subjective task preferences complicate accurate task anticipation and guidance. To address these challenges, we introduce the Multi-Modal Transformer Fusion and Recurrent Units (MMTFRU) Network for egocentric activity anticipation, utilizing multimodal fusion to improve prediction accuracy. Integrated with the Operator Action Monitoring Unit (OAMU), the system provides proactive operator guidance, preventing deviations in the assembly process. OAMU employs two strategies: (1) Top-5 MMTF-RU predictions, combined with a reference graph and an action dictionary, for next-step recommendations; and (2) Top-1 MMTF-RU predictions, integrated with a reference graph, for detecting sequence deviations and predicting anomaly scores via an entropy-informed confidence mechanism. We also introduce Time-Weighted Sequence Accuracy (TWSA) to evaluate operator efficiency and ensure timely task completion. Our approach is validated on the industrial Meccano dataset and the largescale EPIC-Kitchens-55 dataset, demonstrating its effectiveness in dynamic environments.

Ren Zhaopeng, Huang Zhe, Zhao Tingqi et al.

The violent swinging motion of a payload imposes significant safety problems for the operation of offshore ship-mounted cranes (offshore cranes). We therefore propose a stable experimental hoisting platform for an offshore crane payload positioning system with a parallel cable-driven method (PP-PCDM), and an adaptive cable-drive anti-swing tension (ACAT) control method based on the PP-PCDM is developed to resolve the problem of swinging of the payload by limiting its spatial position. The PP-PCDM enables synchronous tracking of the movement of the payload when the crane is working. When the payload deviates from a stable state due to an external disturbance, the anti-swing cables are immediately retracted or released based on the feedback signal. The spatial position of the payload is then limited by adjusting the length and tension of the parallel cables until the payload appears stationary from the perspective of the ship’s deck. Operational safety and efficiency is substantially improved, and the proposed PP-PCDM structure and ACAT control method can be applied to a variety of different types of cranes. The results of simulations and physical experiments show that the anti-swing effect exceeds 89.86%. The PP-PCDM enables excellent performance of synchronous tracking and hoisting assistance, and ensures that the rated lifting weight of the offshore crane is not affected.

Guihua Huang, Cuicui Tian, Liangdi Wei et al.

<i>Pyropia yezoensis</i> is the most widely cultivated and economically important alga. Affected by climate change, the cultivation of <i>P. yezoensis</i> has gradually migrated to the northern coast of China, increasing from 6.8% in 2019 to 19.5% in 2023. To date, the genetic impact of northern migration on cultivation resources has not been assessed and analyzed extensively. Here, DNA barcoding (<i>rbc</i>L and <i>cox</i>1) and the presence/absence of intronic-ORFs in mitochondrial regions (<i>rnl</i> and <i>cox</i>1) were applied to investigate genetic diversity in 44 <i>P. yezoensis</i> specimens from 17 aquaculture farms in China, with comparisons to Korean and Japanese cultivated resources. The lower intraspecific variation was 0.31% for the <i>cox</i>1 gene and 0.14% for the <i>rbc</i>L gene, with three haplotypes, indicating that intensive selection and breeding during cultivation had narrowed the germplasm genetic variation. The intron structure of mitochondrial regions showed that the cultivated resources had 17 phenotypes, and the northern specimens shared 35.3% of genotypes with the southern specimens, indicating that the cultivated <i>P. yezoensis</i> is expanding its cultivation ranges through north migration. Even with lower genetic diversity, the northern area of cultivation had already developed 17.6% site-specific specimens. The genetic diversity of cultivated <i>P. yezoensis</i> from the Northwest Pacific is also discussed. Our work provides a preliminary framework for <i>P. yezoensis</i> breeding and cultivation under climate change.

Nick van der Geest, Lorenzo Garcia, Roy Nates et al.

Sea turtles gracefully navigate their marine environments by flapping their pectoral flippers in an elegant routine to produce the required hydrodynamic forces required for locomotion. The propulsion of sea turtles has been shown to occur for approximately 30% of the limb beat, with the remaining 70% employing a drag-reducing glide. However, it is unknown how the sea turtle manipulates the flow during the propulsive stage. Answering this research question is a complicated process, especially when conducting laboratory tests on endangered animals, and the animal may not even swim with its regular routine while in a captive state. In this work, we take advantage of our robotic sea turtle, internally known as Cornelia, to offer the first insights into the flow features during the sea turtle’s propulsion cycle consisting of the downstroke and the sweep stroke. Comparing the flow features to the animal’s swim speed, flipper angle of attack, power consumption, thrust and lift production, we hypothesise how each of the flow features influences the animal’s propulsive efforts and cost of transport (COT). Our findings show that the sea turtle can produce extremely low COT values that point to the effectiveness of the sea turtle propulsive technique. Based on our findings, we extract valuable data that can potentially lead to turtle-inspired elements for high-efficiency underwater drones for long-term underwater missions.

Xin Shi, Pengfei Chen, Linying Chen

Due to the influence of the natural environment, it is very challenging to control the movement of ships to navigate safely and avoid potential risks induced by external environmental factors, especially for the development of autonomous ships in inland or restricted waterways. In this research, we propose an integrated approach for ship heading control that improves the timeliness and robustness of navigation. Recursive least squares and backward propagation neural networks are utilized to identify the ship motion model parameters under the influence of external factors and predict their development in real time. A particle swarm optimization-integrated Fractional Order Proportion Integration Differentiation (FOPID) controller is then designed based on the dynamically identified motion model to achieve accurate heading control for ships navigating in restricted waterways. A case study was conducted based on the Korea Venture Large Crude Carrier 2 (KVLCC2) model to verify the effectiveness, and a comparison between the conventional FOPID controller and the improved FOPID controller was also conducted. The results indicate that the proposed identification–prediction–optimization FOPID controller has faster speed on stabilization and has higher robustness against external influences, which could provide added value for the development of a motion controller for the autonomous ship for inland and restricted waterway navigation.

Markes E. Johnson, Ginni Callahan

This project follows a tradition of survey work undertaken to appraise physical and biological damage in the aftermath of hurricane-strength winds and waves at a given locality where conditions were well documented prior to the arrival of a particular storm. The locality is the 12 m limestone terrace at Arroyo Blanco on the eastern shores of Isla del Carmen in Baja California Sur, Mexico. A study undertaken in February 2018 established that the surface of the terrace is covered by a coastal boulder deposit that features large slabs of limestone pealed from the outer edge by strong surf attributed to storms of hurricane intensity but unknown date. The largest slabs tend to be rectilinear in shape vulnerable to dislodgement along horizonal bedding planes and weaknesses in vertical joints. These blocks are sufficiently large and weigh enough that movement by humans without necessary mechanical equipment would be impossible. Hurricane Kay, rated as a Category 2 storm, struck the island on 8 September 2022 and an effort was made to visit the area for reconnaissance and detailed survey work soon afterwards. Although a Category 2 storm lacked the energy to remobilize the largest limestone slabs on the terrace, it was found that the storm was sufficient to disturb the adjacent seabed and redeposit as many as 44 sea fans onto the terrace by overwash; the sea fans belonged to the species <i>Pacifigorgia adamsi</i>. Moreover, a species of land plant common to the limestone terrace is the Gulf Star Violet (<i>Stenotis mucronate)</i>; it suffered significant desiccation and death due to saltwater exposure. The occurrence of large potholes on the limestone terrace represents a style of physical erosion previously undocumented at the locality and rarely seen elsewhere on rocky shores.

Michael L Brodie

Data science is not a science. It is a research paradigm. Its power, scope, and scale will surpass science, our most powerful research paradigm, to enable knowledge discovery and change our world. We have yet to understand and define it, vital to realizing its potential and managing its risks. Modern data science is in its infancy. Emerging slowly since 1962 and rapidly since 2000, it is a fundamentally new field of inquiry, one of the most active, powerful, and rapidly evolving 21st century innovations. Due to its value, power, and applicability, it is emerging in over 40 disciplines, hundreds of research areas, and thousands of applications. Millions of data science publications contain myriad definitions of data science and data science problem solving. Due to its infancy, many definitions are independent, application specific, mutually incomplete, redundant, or inconsistent, hence so is data science. This research addresses this data science multiple definitions challenge by proposing the development of coherent, unified definition based on a data science reference framework using a data science journal for the data science community to achieve such a definition. This paper provides candidate definitions for essential data science artifacts that are required to discuss such a definition. They are based on the classical research paradigm concept consisting of a philosophy of data science, the data science problem solving paradigm, and the six component data science reference framework (axiology, ontology, epistemology, methodology, methods, technology) that is a frequently called for unifying framework with which to define, unify, and evolve data science. It presents challenges for defining data science, solution approaches, i.e., means for defining data science, and their requirements and benefits as the basis of a comprehensive solution.

N. Werner, J. Řípa, C. Thöne et al.

This is the first in a collection of three papers introducing the science with an ultra-violet (UV) space telescope on an approximately 130~kg small satellite with a moderately fast re-pointing capability and a real-time alert communication system approved for a Czech national space mission. The mission, called Quick Ultra-Violet Kilonova surveyor - QUVIK, will provide key follow-up capabilities to increase the discovery potential of gravitational wave observatories and future wide-field multi-wavelength surveys. The primary objective of the mission is the measurement of the UV brightness evolution of kilonovae, resulting from mergers of neutron stars, to distinguish between different explosion scenarios. The mission, which is designed to be complementary to the Ultraviolet Transient Astronomy Satellite - ULTRASAT, will also provide unique follow-up capabilities for other transients both in the near- and far-UV bands. Between the observations of transients, the satellite will target other objects described in this collection of papers, which demonstrates that a small and relatively affordable dedicated UV-space telescope can be transformative for many fields of astrophysics.

GAO Jingjie, WANG Wei, SHEN Xiaohong

In order to resolve the conflicts between the communication traffic and the localization accuracy, a self-localization algorithm with adaptive and dynamic observation period for mobile underwater acoustic networks (MUANs) was proposed to improve the localization performance. First, an adaptive and dynamic observation period selection scheme was designed, which could generate a non-uniform observation period vector according to the residual change. Then, based on the non-uniform observation period vector, a self-localization algorithm was proposed, which could precisely predict the trajectory of each mobile node in the network. The simulation results show that the proposed algorithm, which could balance the tradeoff between the localization accuracy and the communication cost, is more suitable for the underwater environment.

Qiwei Zhao, Xin Teng, Panpan Zhang et al.

In the context of carbon peaking and carbon neutrality (“double carbon”), it is urgent to clarify the effect of marine spatial planning (MSP) on carbon sink increases and emission reductions, since such planning acts as a spatial governance tool for the earth’s largest carbon pool. In this paper, a linkage model between marine spatial functional zones and carbon distribution is established. To explore the relationship between marine spatial functional zones and carbon, the study analyzed the carbon increase or reduction role of sea-use activities in each zone and considered the carbon sequestration function of the marine ecosystem itself. A marine spatial pattern of “Two Spaces and Four Carbon Areas” is proposed to present the linkage. A carbon distribution pattern in marine space is delimited using the linkage model and the current MSP in the case study of the city of Tangshan, Hebei, China. Some measures have been taken or planned to be taken in Tangshan to improve the carbon sink function of the ecosystem and the marine space. The supporting role of MSP in achieving the “double carbon” goal is studied, and the paths and suggestions for integrating the “double carbon” goal into MSP are explored.

Zhenwei Chen, Jialong Jiao, Qiang Wang et al.

In this paper, both numerical and experimental methods are adopted to study the fluid–structure interaction (FSI) problem of a wedge structure with stiffeners impacted with water during the free-falling water entry process. In the numerical model, a partitioned two-way couple of CFD and FEM solvers is applied to deal with the FSI problem, where the external fluid pressure exported from the CFD simulation is used to derive the structural responses in the FEM solver, and the structural deformations are fed back into the CFD solver to deform the mesh. Moreover, a tank experiment using a steel wedge model that has the same structural properties is also conducted to compare with the numerical results. Verification and validation of the numerical results indicate that the CFD-FEM coupled method is feasible and reliable. The slamming response results by numerical simulation and experiments, including displacement, velocity, acceleration, slamming pressure, deformation, structural stresses and total forces on the wedge, accounting for hydroelasticity effects in different free falling height conditions are comprehensively analyzed and discussed.

Zhanyuan He, Shouxian Zhu, Jinyu Sheng

A nested-grid ocean circulation modelling system (NGMS-swYS) is used for examining the impact of tides and winds on the three-dimensional (3D) circulation, hydrography and seasonal variability over the southwestern Yellow Sea (swYS). The modelling system is based on the Princeton Ocean Model (POM) and uses a nested-grid setup, with a fine-resolution (~2.7 km) inner model nested inside a coarse-resolution (~9.0 km) outer model. The domain of the outer model covers the China Seas and adjacent deep ocean waters. The domain of the fine-resolution inner model covers the swYS and adjacent waters. The NGMS-swYS is driven by a suite of external forcings, including the atmospheric forcing, tides, freshwater discharge and currents specified at the lateral open boundaries. A comparison of model results with observations and previous numerical studies demonstrates the satisfactory performance of the NGMS-swYS in simulating tides, seasonal mean circulation and distribution of temperature and salinity. Five additional numerical experiments were conducted using NGMS-swYS with different combinations of external forcing. Analysis of model results demonstrates that the monthly mean circulation over the swYS is affected significantly by tides and winds, with large seasonal variability. The northward Subei Shoal Current occurred in both winter and summer months in 2015, with persistent strong southeastward mean currents induced by tides along the 50 m isobath. Model results also demonstrated that strong wind-induced currents occurred with large sea surface cooling during Typhoon Chan-Hom.

George Boateng, Samuel John, Andrew Glago et al.

Africa has a high student-to-teacher ratio which limits students' access to teachers. Consequently, students struggle to get answers to their questions. In this work, we extended Kwame, our previous AI teaching assistant, adapted it for science education, and deployed it as a web app. Kwame for Science answers questions of students based on the Integrated Science subject of the West African Senior Secondary Certificate Examination (WASSCE). Kwame for Science is a Sentence-BERT-based question-answering web app that displays 3 paragraphs as answers along with a confidence score in response to science questions. Additionally, it displays the top 5 related past exam questions and their answers in addition to the 3 paragraphs. Our preliminary evaluation of the Kwame for Science with a 2.5-week real-world deployment showed a top 3 accuracy of 87.5% (n=56) with 190 users across 11 countries. Kwame for Science will enable the delivery of scalable, cost-effective, and quality remote education to millions of people across Africa.

Chia-Nan Wang, Ming-Hsien Hsueh, Chao-Jung Lai et al.

During ship block construction, watertight bulkheads weld of every cabin of ships need to undergo stress testing according to the tanks’ test plan. Every incomplete bulkhead cannot be sprayed in order to protect them after sandblasting; this seriously affects the process of construction. Therefore, the issue of this study is to maintain the integrity of the painting quality and reduce the destruction of the paint, ship-building personnel seek how best to complete the block operation. The aim of this project is to improve the recent watertight bulkheads fillet air test operations in the construction stage using TRIZ (theory of inventive problem solving), promote the ground painting session integrity of every ship, improve the tanks’ test plan in the dock, and reduce the time spent on dismantling operations and the painting operation. Through the TRIZ, this study proposed lots of improvements, some of which are: the watertight cabins can finish the tanks test plan completely, and the integrity of the ground painting can be promoted to reduce the range of cabin test in the dock and reduce watertight bulkheads’ dismantling time. Moreover, because of the considerate reduction of the destruction of the coating, the painting operation is of good quality. The results demonstrate that the TRIZ successfully controls the production quality during construction, reduces working time, and promotes full efficiency. This study saved more than US$1 million of the outsourcing fee.