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The article focuses on the failure of Defence White Paper 2013 of Australia in tackling the challenges that the Australian Defence Force (ADF) is facing. It mentions that the White Paper fails to address the issues between the U.S. and China. It informs that the plan to replace Collins Class submarine is costly and time consuming.

The article highlights several award winning papers published in the periodical including mechanism of submarine spreading failures; development of thermohydro- mechanical numerical models; and the Crossrail tunnels in London Clay by earth pressure balance machines.

This paper is a contribution to a better understanding of tsunamigenic potential from large submarine earthquakes. Here, we analyse the tsunamigenic potential of large earthquakes occurred worldwide with magnitudes around Mw 7.0 and greater, during a period of 1 year, from June 2013 to June 2014. The analysis involves earthquake model evaluation, tsunami numerical modelling, and sensors' records analysis in order to confirm the generation or not of a tsunami following the occurrence of an earthquake. We also investigate and discuss the sensitivity of tsunami generation to the earthquake parameters recognized to control the tsunami occurrence, including the earthquake magnitude, focal mechanism and fault rupture depth. A total of 23 events, with magnitudes ranging from Mw 6.7 to Mw 8.1 and hypocenter depths varying from 10 up to 585 km, have been analyzed in this study. Among them, 52% are thrust faults, 35% are strike-slip faults, and 13% are normal faults. Most analyzed events have been occurred in the Pacific Ocean. This study shows that about 39% of the analyzed earthquakes caused tsunamis that were recorded by different sensors with wave amplitudes varying from few centimetres to about 2 m. Some of them caused inundations of low-lying coastal areas and significant damages in harbours. On the other hand, tsunami numerical modeling shows that some of the events, considered as non-tsunamigenic, might trigger small tsunamis that were not recorded due to the absence of sensors in the near-field areas. We also find that the tsunami generation is mainly dependent of the earthquake focal mechanism and other parameters such as the earthquake hypocenter depth and the magnitude. The results of this study can help on the compilation of tsunami catalogs. [ABSTRACT FROM AUTHOR]

China's latest defence white paper, published on 31 March, once again demonstrated that although the People's Liberation Army (PLA) may be becoming marginally more transparent, it is still circumspect when it comes to revealing details about its military development. Over the last decade, the international media and other governments – notably the United States in the Pentagon's annual report to Congress on the military and security developments in China-have made much of the PLA's development of new capabilities that will allow it to project its power more effectively over greater distances. Among these new capabilities, developments in ballistic and cruise missiles, submarines, space and cyber warfare have been key, though the PLA's development of an aircraft carrier and combat aircraft with stealth characteristics have attracted international attention. [ABSTRACT FROM PUBLISHER]

Benefiting from the relatively benign environment of the Asia-Pacific of the past sixty years, Australia's government has been able to go beyond its stated ‘Defence of Australia’ policy to undertake military operations outside of its immediate neighbourhood, in support of its allies. As austerity begins to bite, however, Australian defence planners no longer have the luxury of creating a ‘balanced force’ – and this at a strategically critical time in the region, as major powers rise and the US calls for greater support from its partners. Andrew Davies analyses what the future may hold for Australian defence, with key decisions about the submarine programme to provide the first test. [ABSTRACT FROM AUTHOR]

Definite stereotype for the outward look of submarines was worked out in the process of evolution. It is very difficult to take into account all inner and outside factors having an influence on the choice of submarine hull shape. Choosing either factor, designers’ model a great variety of outside lines. A light hull of a submarine is the outer nonwatertight hull which provides a hydrodynamically efficient shape. The pressure hull is the inner hull of a submarine; this holds the difference between outside and inside pressure. Closed algebraic surfaces with the main cross-sections in the form of three superellipses lying in three coordinate planes can help to select a submarine form during early-stage design. Having used a parallel middle body, one can extend considerably the choice of suitable shapes. In this paper, a method of modeling smooth compound closed algebraic surfaces that approximates the outside lines of a submarine is presented. The authors offer to form an outside submarine hull from six fragments of algebraic surfaces. The whole hull surface and its fragments are given by the same parametric equations. A method is illustrated in three examples, and it is realized easily in the form of a computer program. The initial data contain large quantities of constants, and it gives an opportunity to consider an infinitely large quantity of variants of submarine hull surfaces. [ABSTRACT FROM AUTHOR]

The Danish media landscape, renowned for its commitment to ethical journalism, faces challenges when covering sensational crimes, often leading to breaches of established ethical codes. This research paper investigates the dynamics of sensationalism in crime reporting within Denmark, focusing on the ethical codes that are most susceptible to violations. Using the 'Submarine Case' as a case study, the paper explores how media coverage of sensational crimes can lead to ethical code breaches, with a specific emphasis on codes related to court reporting, family circumstances, and public interest. [ABSTRACT FROM AUTHOR]

The Norway lobster (Nephrops norvegicus) is one of the most important fishery items for the EU blue economy. This paper describes a software architecture based on neural networks, designed to identify the presence of N. norvegicus and estimate the number of its individuals per square meter (i.e. stock density) in deep-sea (350–380 m depth) Fishery No-Take Zones of the northwestern Mediterranean. Inferencing models were obtained by training open-source networks with images obtained from frames partitioning of in submarine vehicle videos. Animal detections were also tracked in successive frames of video sequences to avoid biases in individual recounting, offering significant success and precision in detection and density estimations. [ABSTRACT FROM AUTHOR]

The article reports on the commitment of the Federal Labor Government to acquire 12 submarines for the Royal Australian Navy to be set up in South Australia, in which the commitment will be strengthened as part of the 2013 Defence White Paper. It says that the move will continue the relationship between South Australia and the Commonwealth in support of region's maritime industry. It also mentions the appointment of David Gould who will oversee the maintenance of the Future Submarine Project.

As the noise reduction performance of submarines continues to improve, it is difficult to detect and track submarines through acoustic detection techniques. Therefore, nonacoustic submarine detection techniques are becoming more and more important. The submarine movement will leave a wake vortex, and the information of the wake vortex can be used to invert the maneuvering state of the submarine. However, the wake vortex is constantly dissipated in the evolution process, and the strength of the wake vortex is constantly reduced, resulting in the gradual weakening of the characteristics of the wake vortex, which makes the inversion of submarine operating state difficult and less accurate. In order to solve the above problems, this paper proposes an improved wake vortex-based inversion method for submarine maneuvering state. Firstly, a random finite set of submarine wake vortex observation features is established to obtain the feature with the highest correlation degree with submarine maneuvering state in the random finite set. Secondly, the multiscale fusion module and attention mechanism are used to re-encode the weak features of the wake vortex image, and the salient features of the wake vortex image are extracted. Finally, the manipulation state of the wake vortex image is retrieved by the extracted salient features. The experimental results show that the average inversion accuracy of the proposed algorithm is improved by 1.27% in terms of manipulating state inversion of weak feature wake vortex images. The algorithm in this paper can realize the inversion of submarine maneuvering state in the case of weak submarine wake vortex image features and incomplete feature information. It provides the basis for the detection technology based on the submarine wake characteristics. [ABSTRACT FROM AUTHOR]

The safe and efficient production of marine natural gas hydrates faces the challenges of seabed geological risk issues. Geological risk issues can be categorized from weak to strong threats in four aspects: sand production, wellbore instability, seafloor subsidence, and submarine landslides, with the potential risk of natural gas leakage, and the geological risk problems that can cause secondary disasters dominated by gas eruptions and seawater intrusion. If the gas in a reservoir is not discharged in a smooth and timely manner during production, it can build up inside the formation to form super pore pressure leading to a sudden gas eruption when the overburden is damaged. There is a high risk of overburden destabilization around production wells, and reservoirs are prone to forming a connection with the seafloor resulting in seawater intrusion under osmotic pressure. This paper summarizes the application of field observation, experimental research, and numerical simulation methods in evaluating the stability problem of the seafloor surface. The theoretical model of multi-field coupling can be used to describe and evaluate the seafloor geologic risk issues during depressurization production, and the controlling equations accurately describing the characteristics of the reservoir are the key theoretical basis for evaluating the stability of the seafloor geomechanics. It is necessary to seek a balance between submarine formation stability and reservoir production efficiency in order to assess the optimal production and predict the region of plastic damage in the reservoir. Prediction and assessment allow measures to be taken at fixed points to improve reservoir mechanical stability with the numerical simulation method. Hydrate reservoirs need to be filled with gravel to enhance mechanical strength and permeability, and overburden need to be grouted to reinforce stability. [ABSTRACT FROM AUTHOR]

The article presents abstracts on naval topics including the impact of sloshing in tanks in hull girder bending movements of vessels, the creation of design charts for submarine pressure hulls and the examination of twin-screw naval ships maneuverability behavior.

To enhance the anti-submarine and search capabilities of multiple Unmanned Aerial Vehicle (UAV) groups in complex marine environments, this paper proposes a flexible action-evaluation algorithm known as Knowledge-Driven Soft Actor-Critic (KD-SAC), which can effectively interact with real-time environmental information. KD-SAC is a reinforcement learning algorithm that consists of two main components: UAV Group Search Knowledge Base (UGSKB) and path planning strategy. Firstly, based on the UGSKB, we establish a cooperation search framework that comprises three layers of information models: the data layer provides prior information and fundamental search rules to the system, the knowledge layer enriches search rules and database in continuous searching processes, and the decision layer utilizes above two layers of information models to enable autonomous decision-making by UAVs. Secondly, we propose a rule-based deductive inference return visit (RDIRV) strategy to enhance the knowledge base of search. The core concept of this strategy is to enable UAVs to learn from both successful and unsuccessful experiences, thereby enriching the search rules based on optimal decisions as exemplary cases. This approach can significantly enhance the learning performance of KD-SAC. The subsequent step involves designing an event-based UGSKB calling mechanism at the decision-making level, which calls a template based on the target and current motion. Finally, it uses a punishment function, and is then employed to achieve optimal decision-making for UAV actions and states. The feasibility and superiority of our proposed algorithm are demonstrated through experimental comparisons with alternative methods. The final results demonstrate that the proposed method achieves a success rate of 73.63% in multi-UAV flight path planning within complex environments, surpassing the other three algorithms by 17.27%, 29.88%, and 33.51%, respectively. In addition, the KD-SAC algorithm outperforms the other three algorithms in terms of synergy and average search reward. [ABSTRACT FROM AUTHOR]

Submarine garbage is constantly destroying the marine ecological environment and polluting the ocean. It is critical to use detection methods to quickly locate and identify submarine garbage. The background of submarine garbage images is much more complex than that of natural scene images, with object deformation and missing contours putting higher demands on the detection network. To solve the problem of low accuracy under complex backgrounds, full stage networks with auxiliary focal loss and multi-attention module are proposed for submarine garbage object detection based on YOLO. To maximize the gradient combination, a hierarchical fusion feature mechanism and a segmentation and merging strategy are used in this paper to optimize the difference in gradient combination to obtain full-stage features. Then the criss-cross attention module is used to precisely extract multi-scale features of small object dense regions while removing noise information from complex backgrounds. Finally, the auxiliary focal loss function addresses the issue of unbalanced positive and negative samples, focusing on the learning of difficult samples while improving overall detection precision. Based on comparative experiments and ablation experiments, the FSA networks achieved state-of-the-art performance, and is applicable to the real-time object detection of submarine garbage in complex backgrounds. [ABSTRACT FROM AUTHOR]

The victories of the Go-playing artificial intelligence (AI) "AlphaGo" against professional player Lee Sedol in 2016 had a profound impact on public and academic perceptions of AI. This event shocked observers, as the ability of a machine to defeat a world champion human in a highly complex game seemed to indicate that a machine had achieved human-like—or more than human—intelligence. But why was AlphaGo so readily anthropomorphized by academic and non-academic audiences alike? Drawing from existing analyses of reactions to and arguments concerning AlphaGo and AI generally, this paper argues that "generative" cognitive science—a school of thought exemplified by the linguistic work of Noam Chomsky—offers two novel contributions to this subject. First, generativism sheds light on an irrational double standard in the study of the human mind in contrast to the study of non-cognitive systems—"methodological dualism"—which, I argue, has been transferred to evaluations of AlphaGo and other AI. Second, by exposing this irrational double standard in perceptions of AI, I employ generativism's more well-known arguments concerning the nature of human intelligence and its scientific study to the evaluation of AI, exposing deficient interpretations widely used in the case of AlphaGo and AI generally. [ABSTRACT FROM AUTHOR]

Repetitive transcranial magnetic stimulation (rTMS) is a rapidly developing therapeutic modality for the safe and effective treatment of neuropsychiatric disorders. However, clinical rTMS driving systems and head coils are large, heavy, and expensive, so miniaturized, affordable rTMS devices may facilitate treatment access for patients at home, in underserved areas, in field and mobile hospitals, on ships and submarines, and in space. The central component of a portable rTMS system is a miniaturized, lightweight coil. Such a coil, when mated to lightweight driving circuits, must be able to induce B and E fields of sufficient intensity for medical use. This paper newly identifies and validates salient theoretical considerations specific to the dimensional scaling and miniaturization of coil geometries, particularly figure-8 coils, and delineates novel, key design criteria. In this context, the essential requirement of matching coil inductance with the characteristic resistance of the driver switches is highlighted. Computer simulations predicted E- and B-fields which were validated via benchtop experiments. Using a miniaturized coil with dimensions of 76 mm × 38 mm and weighing only 12.6 g, the peak E-field was 87 V/m at a distance of 1.5 cm. Practical considerations limited the maximum voltage and current to 350 V and 3.1 kA, respectively; nonetheless, this peak E-field value was well within the intensity range, 60–120 V/m, generally held to be therapeutically relevant. The presented parameters and results delineate coil and circuit guidelines for a future miniaturized, power-scalable rTMS system able to generate pulsed E-fields of sufficient amplitude for potential clinical use. [ABSTRACT FROM AUTHOR]

At present, the calculation method of ice load on surface navigation ships has been very mature, but the calculation method of submarine ice load is very few. The reasonable evaluation of submarine ice load has become an urgent problem to be solved. In this paper, the mechanical characteristics of the submarine surfacing ice-breaking process are systematically analyzed. Based on the theory of plate and shell, the theoretical calculation models of ice-breaking resistance of the submarine command tower and hull are established, respectively, and the ice load calculation method of the command tower and the hull is obtained. Then, the submarine model SUBOFF is used to perform the numerical simulation of the submarine's ice-breaking and surfacing process. The numerical result is compared with the ice-breaking resistance calculation model. The results show that the ice-breaking resistance calculation model proposed in this paper is consistent with the numerical simulation results, and the influence of parameters such as ice mechanical properties, the upper area of the command tower, and initial crack length on ice-breaking resistance is established. The calculation model in this paper can provide a theoretical reference for the optimization design of polar submarine structures. [ABSTRACT FROM AUTHOR]

This paper develops a depth‐averaged theory to investigate submarine landslides and resulting water waves. The problems here consist of a pure fluid regime and a mixture regime of grains and fluid. Both regimes separate from one another by an interface, which is a material surface for grains. While the downslope velocities of the both phases are assumed to be identical in the mixture regime, the velocity shear causes a rearrangement of grains, which induces a vertical relative motion between the phases. The established theory consists of five coupled conservation equations, which describe the evolution of the pure fluid thickness, the mixture thickness, the solids volume fraction, and depth‐averaged velocities. To handle nonconservative products emerging in the equations, a new coordinate system is introduced to rewrite the equation system in an equivalent form, so that numerical solutions are insensitive to the choice of discretization of nonconservative products, which enables us to accurately characterize the dynamic behaviors of particles in the collapse experiments of underwater particles and describe free‐surface wave profiles. It is shown that the computed results are in good agreement with the experiments reported in previous literatures. Plain Language Summary: Developing an accurate and rigorous model to describe the motion of submarine landslides and the evolution of the induced water wave remains a challenge to date. Existing models usually simplify the submarine mass as a sling box or a deformable rheological material which is unable to interpret certain fast‐moving and some slow‐moving granular flows that differ only in their compactness. In this paper, the existing models are improved by taking account of the dilatancy effects of the particles. Numerical results of underwater granular collapse show that the predictions of the temporal evolution of the thickness profiles and the final deposit morphology using the current model are in better agreement with experiments compared to the existing models. The present model also provides a better prediction in the wave profiles induced by submarine landslides, which makes the present theory very promising to investigate natural geophysical flows in the future. Key Points: A depth‐averaged model is presented, which considers excess pore fluid pressure and fluid mass transfer across the avalanche surfaceA robust numerical method is used, so that the computed solution is insensitive to the way nonconservative products are discretizedSignificant improvements in the prediction of the grain thickness profiles and the free‐surface waves are found compared with existing models [ABSTRACT FROM AUTHOR]

This paper aims to show the scale effects of vertical maneuvering derivatives for an underwater vehicle using computational fluid dynamics (CFD). The model scale and full-scale benchmark DARPA suboff hull forms were used in numerical vertical planar motion mechanism simulations to achieve this aim. The heave forces, pitch moments, and Euler coefficients are calculated together with the linear vertical maneuvering derivatives by implementing the Fourier series expansion approach. The results show that the coupled added mass terms are significantly influenced by the scale effects, whereas the impact of scale effects on the decoupled added mass and coupled and decoupled damping terms is negligible. Considering that the effects of the coupled added mass on the vertical maneuvering characteristics are almost negligible, the vertical maneuvering of a submarine is slightly influenced by the scale effects. [ABSTRACT FROM AUTHOR]

Maneuverability is one of the submarine's most important features, and is closely related to hydrodynamic coefficients. The submarine standard motion equation is the most commonly used hydrodynamic mathematical model, estimating more than 100 hydrodynamic coefficients. This paper applies the Bayesian ridge regression model to identify a submarine's hydrodynamic coefficients. Specifically, the proposed approach combines the URANS equation with a six-degree-of-freedom motion model and a body force propeller model, and uses overset grid technology to simulate the underwater six-degree-of-freedom navigation motion of the SUBOFF submarine. The submarine's required hydrodynamic coefficients are obtained by collecting relevant velocity and angular velocity data and applying the Bayesian ridge regression model for data identification. Meanwhile, CFD simulation of the restraint model test for the SUBOFF submarine is conducted to obtain the related hydrodynamic coefficients. Through comparative experiments, we validate that the proposed Bayesian ridge regression model identification method is effective and reliable; most of the errors in the hydrodynamic coefficients were within 10%, with a maximum error of −43.26%, providing more comprehensive and timely hydrodynamic coefficients than traditional CFD restraint model tests. Furthermore, the hydrodynamic coefficient identification results were used to invert the submarine's spatial motion, and we demonstrated that the resulting trajectory, velocity, and angular velocity curves all fit well. [ABSTRACT FROM AUTHOR]

Engine base plays an important role in a submarine. To enhance the vitality of the submarine, the base should resist shock under underwater non-contact explosion situations. To improve the submarine's acoustic-stealth characteristics, the base also needs to have an excellent vibration isolation ability. This paper establishes a multi-level and multi-objective optimisation method for the submarine base structure. The strong coupling interaction between the submarine structure and seawater is considered. Taking structure shock safety, vibration isolation and base light-weight as multi-objectives, the artificial intelligence technology is applied to optimise the size and shape of the base structure. With the optimisation, the total vibration level difference in the base is improved by 3.06 dB and the mass of the base is reduced by 26.16%. The adopted optimisation method in this paper could give references for the engineering design of the submarine base. [ABSTRACT FROM AUTHOR]

The objective of this paper is to predict the noise radiated from submarine propellers with different control surface types (the cross- and X-type). When the propellers are free from cavitation, such as those of submarines at a diving depth, the radiated noise dominate, due to unsteady propeller forces. A well-known submarine model (DARPA SUBOFF) is taken as the computing sample. Simulations for hydrodynamics, including stern wakes and unsteady propeller forces, are carried out by using CFD (Computational Fluid Dynamics) technology, and the results are compared with the experimental data. The accuracy of the predicted noise depends on the CFD results. Comparisons between the CFD results and the experimental data are in good agreement. The CFD results are treated as dipole strengths in the linear wave theory to predict the radiated noise caused by the unsteady forces of the propeller. It is found that, when the control surface is of the X-type, the propeller inflow is more uniform, and the radiated noise can be decreased by about 5 dB compared to the cruciform control surface. [ABSTRACT FROM AUTHOR]

In order to design a controller to control the pitch and depth of the submarine, this paper designs a submarine bow and stern rudder controller based on Closed-loop Gain Shaping Algorithm (CGSA) and nonlinear feedback and modification. The controller design considers the decoupling of the strong coupling of the submarine vertical surface motion model, the effect of wave disturbance and the optimization of the controller output. To verify the effectiveness and superiority of the proposed method, this research compares it with the Independent channel analysis and design (ICAD) method and introduces an evaluation index system to quantify the improvement effect. From the controller design process, the parameters of the CGSA are simple to solve and the engineering meaning is clear. From the simulation results, this controller can reach the setting depth quickly during the depth-changing maneuver. In the depth-keeping navigation stage, the control effect of depth and pitch angle is improved under wave disturbance, and the control energy evaluation index of the bow and stern rudder are reduced by 94.00% and 77.16% respectively, which proves that the controller has robust performance and energy saving effect. A new and efficient control algorithm is proposed for submarine motion control, which reduces the control energy while ensuring the control effect. [ABSTRACT FROM AUTHOR]

This study aims to address the problem in tracking technology in which targeted cruising ships or submarines sailing near the water surface are tracked at low frame rates or with some frames missing in the video image, so that the tracked targets have a large gap between frames, leading to a decrease in tracking accuracy and inefficiency. Thus, in this study, we proposed a water surface dynamic multi-target tracking algorithm based on the fusion of YOLOv7 and DeepSORT. The algorithm first introduces the super-resolution reconstruction network. The network can eliminate the interference of clouds and waves in images to improve the quality of tracking target images and clarify the target characteristics in the image. Then, the shuffle attention module is introduced into YOLOv7 to enhance the feature extraction ability of the target features in the recognition network. Finally, Euclidean distance matching is introduced into the cascade matching of the DeepSORT algorithm to replace the distance matching of IOU to improve the target tracking accuracy. Simulation results showed that the algorithm proposed in this study has a good tracking effect, with an improvement of 9.4% in the improved YOLOv7 model relative to the mAP50-95 value and an improvement of 13.1% in the tracking accuracy in the DeepSORT tracking network compared with the SORT tracking accuracy. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Submarine pipe-in-pipe with thermal insulation layer plays a crucial role in the offshore oil and gas transportation system. This paper presents pollutants distribution in thermal insulation layer of damaged submarine pipe-in-pipe by computational fluid dynamics method. The numerical model has been validated through comparing with other simulation data. In order to considerably mitigate the leakage damage, the influence factors analysis is performed. Finally it is identified that macropores thermal insulation material and larger leakage hole with higher leakage velocity can significantly make the damage more serious. In addition, it is under consideration to install monitoring system on the bottom of the jacket pipe for easier and faster detection of the leaked pollutants, which helps to offer a valuable guidance for formulation of emergency response and protect seawater from direct contamination. [ABSTRACT FROM AUTHOR]

A steady state box model was developed to estimate the methane input into the Black Sea water column at various water depths. Our model results reveal a total input of methane of 4.7 Tg yr-1. The model predicts that the input of methane is largest at water depths between 600 and 700m (7% of the total input), suggesting that the dissociation of methane gas hydrates at water depths equivalent to their upper stability limit may represent an important source of methane into the water column. In addition we discuss the effects of massive short-term methane inputs (e.g. through eruptions of deep-water mud volcanoes or submarine landslides at intermediate water depths) on the water column methane distribution and the resulting methane emission to the atmosphere. Our non-steady state simulations predict that these inputs will be effectively buffered by intense microbial methane consumption and that the upward flux of methane is strongly hampered by the pronounced density stratification of the Black Sea water column. For instance, an assumed input of methane of 179 TgCH4 d-1 (equivalent to the amount of methane released by 1000 mud volcano eruptions) at a water depth of 700m will only marginally influence the sea/air methane flux increasing it by only 3%. [ABSTRACT FROM AUTHOR]

The hydrodynamic interaction between an AUV (Autonomous Underwater Vehicle) and a recovery device, such as a real-scale submarine, is a crucial factor affecting the safe recovery of the AUV. This paper employs the CFD (Computational Fluid Dynamics) method to investigate the hydrodynamic interaction of the AUV and the submarine during the recovery process. Both the AUV and the submarine are considered to be relatively stationary. The results indicate that the submarine has a significant impact on the AUV during the recovery process, with sailing speed and relative positions identified as key influential factors. Due to the influence of the submarine, it can be difficult for the AUV to approach the submarine and be recovered safely. This study provides valuable insights into the hydrodynamic interaction between the AUV and the recovery device, and offers guidance for future submarine recovery operations involving AUVs. By considering the influence of the submarine's position and motion, as well as other relevant factors, it may be possible to improve the stability, safety, and efficiency of AUV recovery operations. [ABSTRACT FROM AUTHOR]

In general, submarines are designed to optimize operation below the water surface because they spend most of their time underwater. On the other hand, the performance in the free surface condition is also important because submarines face a variety of scenarios to complete operational missions, and the free surface condition is unavoidable for port departure and arrival. In the case of a submarine, the numerical accuracy of the potential theory for seakeeping analysis is excellent in submerged conditions, but it is poor in free surface conditions because of nonlinear effects near the free surface area. In this study, STAR-CCM+ was used as a Reynolds-averaged Navier-Stokes (RANS) solver to estimate the seakeeping performance of a Canadian Victoria Class submarine in irregular waves. The results were compared with those of model tests from a published paper. In addition, the potential theory code was also used to assess the seakeeping performance and compare it with computational fluid dynamics (CFD) results. From the calculation results, the motion responses in irregular waves using CFD showed similar trends to the experimental results. In contrast, motion responses from potential code showed significantly larger values than the experimental results. In conclusion, CFD simulations with irregular waves can be a good solution to predict the seakeeping performance of submarines in free surface conditions. [ABSTRACT FROM AUTHOR]

Large-scale rising bubbles exist in some extreme marine engineering fields, such as the exploitation of combustible ice and submarine volcanism. The violent splitting and coalescence process of large-scale rising bubbles with internal pressure comparable to ambient pressure differs greatly from that of the normal small-scale bubbles and high-pressure bubbles. In this paper, the complex splitting and coalescence characteristics of large-scale rising bubbles are studied with a multi-phase smoothed particle hydrodynamics approach. The effects of the arrangement of bubbles, initial centroid distance, and the ratios of bubble radii on the bubble splitting and coalescence characteristics are investigated. The results show that the arrangement of the bubbles dictates whether or not the two bubbles coalesce and influences the coalescence mode of the bubbles further. When two large-scale bubbles are arranged horizontally, the initial spacing of bubbles has minimal influence on the coalescence features, and they always bounce off each other. When the bubbles are not placed horizontally, the bubbles can coalesce in two modes: direct-absorption coalescence and penetrating reverse-absorption coalescence. When arranged vertically, the initial centroid distance affects the coalescence extent of bubbles, and when the vertical distance exceeds five times the bubble radius, the two bubbles do not interact with each other. When the leading bubble is too large relative to the trailing bubble, the large ratios of bubble radii play negative roles in the coalescence of bubbles. [ABSTRACT FROM AUTHOR]

Underwater sensing has a wide range of applications including the location and monitoring of subsurface infrastructures such as cables and pipelines, mapping undersea terrain, the study of marine life, pollution and salinity monitoring and detection of seismic activities. Underwater sensing technologies are also essential to maritime surveillance, detection and tracking of submarines and other underwater objects. Using natural language processing and machine learning, we mined scientific publications to gain insight into underwater sensing research evolution during the 21st century, in terms of technology development and applications. This study offers a comprehensive analysis of the underwater sensing research landscape as well as the temporal evolution of its main research topics. We identified 18 key research topics that offer comprehensive and logical coverage of the research field. Nearly half of them are on a decreasing trend, despite an overall increase in the number of scientific publications. These findings and the extracted patterns can provide researchers and decision-makers with new insights into the field, its characteristics and its development. Our proposed algorithmic approach can also be applied to other areas for technologies of a disruptive nature. [ABSTRACT FROM AUTHOR]

The following article considers the implications of the AUKUS security pact for Australia, noting obstacles to implementing the tripartite security alliance involving the deployment of nuclear technology and the expansion of the current US military presence in Australia. The paper argues that the efforts to implement AUKUS in various ways face three fundamental obstacles, thereby challenging Australia’s militarisation. The first involves challenges in acquiring a nuclear-propulsion submarine fleet both in terms of constructing a new design and purchasing existing models from the US. The second considers the growing unpopularity of AUKUS and efforts to militarise and garrison Australia as a US satellite. The third considers the complexities and challenges of storing nuclear waste arising from the vessels. To that end, the paper concludes that the objectives of the alliance may prove unworkable on several levels. [ABSTRACT FROM AUTHOR]

Copyright of Acta Oceanográfica del Pacífico is the property of Acta Oceanografica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper deals with the resistance, towing, seakeeping, and open water propeller tests of an innovative tourist submarine model. Tests were performed in a 276 m long towing tank. As the submarine model is a complex structure composed of various parts attached to the pressure hull, the largest possible model, in the scale of 1:5.0, was produced, considering the towing tank depth and the capabilities of the measurement equipment. Resistance tests were performed in deep water and on the surface in calm water. The tested speed range in both cases was up to 5.5 knots. To ensure the avoidance of free surface effects, resistance tests in deep water were performed for different draughts and then extrapolated to infinite water depth. Smaller effective powers were found for the surface condition. The results are compared to an independently performed computational fluid dynamics (CFD) analysis using OpenFOAM. A fair agreement between the experimentally and numerically predicted effective power is found, while the reasons for the differences found are explained. The free submarine model was towed with a rope performed for the speed range 1.7 kn–3.5 kn, and the towing force in the rope was measured. Seakeeping tests in irregular beam waves at zero speed were performed to check the flooding risk on open hatches. Open water tests of the main thrusters for propelling the submarine were conducted, indicating that both power demand and propeller thrust are slightly larger compared to the initial estimates. [ABSTRACT FROM AUTHOR]

It is of great significance to expand the functions of submarines by carrying underwater manipulators with a large working space. To suppress the flexible vibration of underwater manipulators, an improved sparrow search algorithm (ISSA) combining an elite strategy and a sine algorithm is proposed for the trajectory planning of underwater flexible manipulators. In this method, the vibration evaluation function is established based on the precise dynamic model of the underwater flexible manipulator and considering complex motion and vibration constraints. Simulation results show that the ISSA algorithm requires only 1/3.68 of the time of PSO. Compared to PSO, SSA and the opposition-based learning sparrow search algorithm (OBLSSA), the optimization performance is improved by 17.3%, 13.1% and 9.7%, respectively. However, because the complex dynamics model of the underwater flexible manipulator leads to large computational effort and a long optimization time, ISSA is difficult to apply directly in practice. To obtain a large number of optimization results in a shorter time, an incremental Kriging-assisted ISSA (IKA-ISSA) is proposed in this paper. Simulation results show that IKA-ISSA has good nonlinear approximation ability and the optimization time is only 3% of that of the ISSA. [ABSTRACT FROM AUTHOR]

This paper presents an overview of the results obtained with different analysis techniques applied to long-range signal recordings of the acoustic event associated with the loss of the Argentinian submarine ARA San Juan that occurred on 15 November 2017 around 500 km off the coast of Chubut, Argentina. The published works including analyses of those signals have mainly considered the source geolocation. In contrast, this work is focused on the nature of the source that generated the registered signals. An inverse problem approach is followed for estimating some features of impulse-like sources through the application of spectral and cepstral analyses to a set of acoustic data associated with an unknown source. The International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) detected an unusual hydroacoustic signal originating in the vicinity of the last known location of the ARA San Juan, reported as a hydroacoustic anomaly, at two of its hydrophone stations located at Ascension Island and Crozet Island, in the central Atlantic Ocean and the southern Indian Ocean, respectively. The analyses performed on the raw acoustic data provided by the CTBTO are also applied to the signals produced by an underwater explosion of a depth charge during a controlled experiment conducted by the Argentinian Navy in a nearby area on 1 December. The propagation effects along these very long-range paths (approximately 7000 km) are calculated using a range-dependent 2D underwater acoustic propagation model based on the resolution of the wide-angle parabolic equation. Results of exhaustive comparative analyses of the signals generated on 15 November and 1 December, together with comparisons between the energy spectral density of recorded and modelled signal levels, reinforce the hypothesis of at least two close and successive implosions with a time lag of 329 ms and a separation of approximately 38 m, with an azimuth to the north in accordance with the expected heading of the submarine. The values obtained are compatible with the submarine dimensions and the course over ground of the submarine towards Mar del Plata harbour. Finally, an optimization process is performed for estimating the depth of occurrence of the acoustic event related to the submarine loss. [ABSTRACT FROM AUTHOR]

Nuclear ballistic missile submarines (SSBNs) are traditionally believed to provide assured second-strike capability and stabilize deterrence. This paper contests this classical assumption in South Asia's context and argues that SSBN capability to become secure and credible deterrent depends upon doctrinal issues, command and communication systems, and operational readiness of SSBN force. In a dyad, if both countries have invulnerable second strike capability, there is less incentive to strike first. Whereas invulnerability of one country incentivizes first strike. In South Asian strategic situation, an assured sea-based second-strike capability may contribute to India's aggressive nuclear posture. This paper evaluates New Delhi's induction of SSBNs in light of its stated notion of minimalism, as declared in its nuclear doctrine, and discusses in the context of traditional stability theory associated with the development of SSBN force. This paper primarily considers deterrence stability and crisis stability as two dependent variables to study how India's sea-based nuclear capability affects strategic stability in South Asia. [ABSTRACT FROM AUTHOR]

Synthetic aperture radar (SAR) imaging has important application potential in sea environments research, such as submarine detection. It has become one of the most significant research topics in the current SAR imaging field. In order to promote the development and application of SAR imaging technology, a MiniSAR experiment system is designed and developed, which provides a platform for related technology investigation and verification. A flight experiment is then conducted to detect the movement of an unmanned underwater vehicle (UUV) through the wake, which can be captured by SAR. This paper introduces the basic structure and the performance of the experimental system. The key technologies for Doppler frequency estimation and motion compensation, the implementation of the flight experiment, and the image data processing results are given. The imaging performances are evaluated, and the imaging capabilities of the system are verified. The system provides a good experimental verification platform to construct the follow-up SAR imaging dataset of UUV wake and investigate related digital signal processing algorithms. [ABSTRACT FROM AUTHOR]

The employability of photonics technology in the modern era's highly demanding and sophisticated domain of aerospace and submarines has been an appealing challenge for the scientific communities. In this paper, we review our main results achieved so far on the use of optical fiber sensors for safety and security in innovative aerospace and submarine applications. In particular, recent results of in-field applications of optical fiber sensors in aircraft monitoring, from a weight and balance analysis to vehicle Structural Health Monitoring (SHM) and Landing Gear (LG) monitoring, are presented and discussed. Moreover, underwater fiber-optic hydrophones are presented from the design to marine application. [ABSTRACT FROM AUTHOR]

The resolution of remote sensing images has increased with the maturation of satellite technology. Ship detection technology based on remote sensing images makes it possible to monitor a large range and far sea area, which can greatly enrich the monitoring means of maritime departments. In this paper, we conducted research on small target detection and resistance to complex background interference. First, a ship dataset with four types of targets (aircraft carriers, warships, merchant ships and submarines) is constructed, and experiments are conducted on the dataset using the object detection algorithm YOLOv4. The Kmeans++ clustering algorithm is used for a priori frame selection, and the migration learning method is used to enhance the detection effect of the YOLOv4. Second, the model is improved to address the problems of missed detection of small ships and difficulty in resisting background interference: the RFB_s (Receptive Field Block) with dilated convolution is introduced instead of the SPP (Spatial Pyramid Pooling) to enlarge the receptive field and improve the detection of small targets; the attention mechanism CBAM (Convolutional Block Attention Module) is added to adjust the weights of different features to highlight salient features useful for ship detection task, which improve the detection performance of small ships and improve the model's ability to resist complex background. Compared to YOLOv4, our proposed model achieved a large improvement in mAP (mean Average Precision) from 77.66% to 91.40%. [ABSTRACT FROM AUTHOR]