Technological Perspectives for Propulsion on Nuclear Attack Submarines

This work aimed at proposing a new combination of technologies to improve military performances and reduce costs of nuclear attack submarines, without overlooking safety constraints. The last generation of nuclear attack submarines increased size to meet safety and operational requirements, imposing huge burden on costs side, reducing fleet size. The limitations of current Technologies employed were qualitatively discussed, explaining their limitations. There are new technologies (plate and shell heat exchangers) and architectural choices, like passive safety, and segregation of safety and normal systems, which may lead to reduction of costs and size of submarines. A qualitative analysis was provided on this combination of technologies, stressing their commercial nature and maturity, which reduced risks. The qualitative analysis showed the strong and weak points of this proposal, which adopted the concept of strength in numbers. Concluding, new Technologies enabled the existence of 3800 t nuclear attack submarines with powerful propulsion systems and good acoustic discretion.

Circadian misalignment on submarines and other non-24-h environments – from research to application

Circadian clocks have important physiological and behavioral functions in humans and other organisms, which enable organisms to anticipate and respond to periodic environmental changes. Disturbances in circadian rhythms impair sleep, metabolism, and behavior. People with jet lag, night workers and shift workers are vulnerable to circadian misalignment. In addition, non-24-h cycles influence circadian rhythms and cause misalignment and disorders in different species, since these periods are beyond the entrainment ranges. In certain special conditions, e.g., on submarines and commercial ships, non-24-h watch schedules are often employed, which have also been demonstrated to be deleterious to circadian rhythms. Personnel working under such conditions suffer from circadian misalignment with their on-watch hours, leading to increased health risks and decreased cognitive performance. In this review, we summarize the research progress and knowledge concerning circadian rhythms on submarines and other environments in which non-24-h watch schedules are employed.

Study of the Dynamic Characteristics of A Cone-Shaped Recovery System on Submarines for Recovering Autonomous Underwater Vehicle

National navies equip their submarines with Autonomous Underwater Vehicle(AUV)technology.It has become an important component of submarine development in technologically-advanced countries.Employing advanced and reliable recovery systems directly improves the safety and operational efficiency of submarines equipped with AUVs.In this paper,based on aerial refueling technology,a cone-shaped recovery system with two different guiding covers(closed structure and frame structure)is applied to the submarine.By taking the Suboff model as the research object,STAR-CCM was used to study the influence of the installation position of the recovery system,and the length of the rigid rod,on the Suboff model.It was found that when the recovery system is installed in the middle and rear of the Suboff model at the same velocity and the same length of the rigid rod,the Suboff model has the good stability and less drag.It experiences the largest drag when being installed in the front of the rigid rod.Moreover,when the recovery system is installed in the front and middle of the rigid rod,the drag increases as its length increases,and the lift decreases as its length increases.Compared with the closed structure guiding cover,the Suboff model will have less drag and better stability when the recovery system uses the frame structure guiding cover.Besides,the deflection and vibration of the rigid rod were also analyzed via mathematical theory.

Cybersecurity for Allied Future Submarines

Cyber has become a supposedly cheap first-strike weapon of political choice by potential adversaries in a milieu placing insurgency, terrorism, international crime and state-based influences in close un-regulated proximity. The merging of electronic and cyber warfare means that not even submarines, however unconnected or firewalled they may be, are immune. The quantum attack surface of submarines is as much in their past, as they are in their designs today and their operations tomorrow: they must survive to be credible and ideally they should even be a contemporary offensive cyber deterrent. Such critical defensive systems require robust security systems engineering and cybersecurity test and evaluation to build and sustain their cyber-resilience. This paper uses Australia’s future submarine program [1]1 to outline key facets needed in a submarine program to achieve cyber resilience, including how to adapt U.S. Department of Defense (DoD) best practices to engineer, test and sustain cyber-resilient submarine systems. Strategies are needed that provision sovereign-owned and operated land-based test sites to design, build, demonstrate and sustain critical submarine systems. This work is most relevant to countries allied to the U.S. and importing submarine capabilities, such as within lesser European powers and also in the Indo-Pacific where both cyber warfare and submarines are proliferating.

Platform Evolution in an Oligo-Miocene Back-arc Basin:An Example from the Central Iran Basin

The Qom Formation is the most important hydrocarbon reservoir target in Central Iran.The Qom platform developed in a back-arc basin during the Oligo-Miocene due to the closing of the Tethyan Seaway.This formation consists of a variety of carbonate and non-carbonate facies deposited on a platform ranging from supratidal to basin.A combination of tectonic and eustatic events led to some lateral and vertical facies variations in the study area.Six third-order depositional sequences and related surfaces were identified regarding vertical facies changes in the studied sections of this Oligo-Miocene succession.According to all results and data,this succession was initially deposited during the Chattian upon a distally steepened ramp of siliciclastic-carbonate composition,including the Bouma sequence.Then,from the late Chattian to the Aquitanian,the platform changed into a homoclinal carbonate ramp with a gentle profile.With respect to tectonic activity,this phase was a calm period during the deposition of the Qom Formation.Finally,a drowned carbonate platform and a rimmed shelf emerged during the Burdigalian,terminated by the continental deposits of the Upper Red Formation.Regarding all geological characteristics,three main tectono-eustatic evolutionary phases have been recognized in the Qom back-arcbasin.

Sedimentary architecture of submarine channel-lobe systems under different seafloor topography:Insights from the Rovuma Basin offshore East Africa

Seafloor topography plays an important role in the evolution of submarine lobes.However,it is still not so clear how the shape of slope affects the three-dimensional(3-D)architecture of submarine lobes.In this study,we analyze the effect of topography factors on different hierarchical lobe architectures that formed during Pliocene to Quaternary in the Rovuma Basin offshore East Africa.We characterize the shape,size and growth pattern of different hierarchical lobe architectures using 3-D seismic data.We find that the relief of the topographic slope determines the location of preferential deposition of lobe complexes and single lobes.When the topography is irregular and presents topographic lows,lobe complexes first infill these depressions.Single lobes are deposited preferentially at positions with higher longitudinal(i.e.across-slope)slope gradients.As the longitudinal slope becomes higher,the aspect ratio of the single lobes increases.Lateral(i.e.along-slope)topography does not seem to have a strong influence on the shape of single lobe,but it seems to affect the overlap of single lobes.When the lateral slope gradient is relatively high,the single lobes tend to have a larger overlap surface.Furthermore,as the average of lateral slope and longitudinal slope gets greater,the width/thickness ratio of the single lobe is smaller,i.e.sediments tend to accumulate vertically.The results demonstrate that the shape of slopes more comprehensively influences the 3-D architecture of lobes in natural deep-sea systems than previously other lobe deposits and analogue experiments,which helps us better understand the development and evolution of the distal parts of turbidite systems.

An MPI parallel DEM-IMB-LBM framework for simulating fluid-solid interaction problems

The high-resolution DEM-IMB-LBM model can accurately describe pore-scale fluid-solid interactions,but its potential for use in geotechnical engineering analysis has not been fully unleashed due to its prohibitive computational costs.To overcome this limitation,a message passing interface(MPI)parallel DEM-IMB-LBM framework is proposed aimed at enhancing computation efficiency.This framework utilises a static domain decomposition scheme,with the entire computation domain being decomposed into multiple subdomains according to predefined processors.A detailed parallel strategy is employed for both contact detection and hydrodynamic force calculation.In particular,a particle ID re-numbering scheme is proposed to handle particle transitions across sub-domain interfaces.Two benchmarks are conducted to validate the accuracy and overall performance of the proposed framework.Subsequently,the framework is applied to simulate scenarios involving multi-particle sedimentation and submarine landslides.The numerical examples effectively demonstrate the robustness and applicability of the MPI parallel DEM-IMB-LBM framework.

Physical and mechanical properties and microstructures of submarine soils in the Yellow Sea

In recent years,the exploration of seabed has been intensified,but the submarine soils of silt and sand in the Yellow Sea area have not been well investigated so far.In this study,the physical and mechanical properties of silt and sand from the Yellow Sea were measured using a direct shear apparatus and their microstructures were observed using a scanning electron microscope.The test results suggest that the shear strength of silt and sand increases linearly with the increase of normal stress.Based on the direct shear test,the scanning electron microscope was used to observe the section surface of sand.It is observed that the section surface becomes rough,with many“V”‐shaped cracks.Many particles appear on the surface of the silt structure and tend to be disintegrated.The X‐ray diffraction experiment reveals that the sand and silt have different compositions.The shear strength of sand is slightly greater than that of silt under high stress,which is related to the shape of soil particles and the mineral composition.These results can be a reference for further study of other soils in the Yellow Sea;meanwhile,they can serve as soil parameters for the stability and durability analyses of offshore infrastructure construction.

Evaluation of the submarine debris-flow hazard risks to planned subsea pipeline systems: a case study in the Qiongdongnan Basin, South China Sea

The ever-increasing deepwater oil and gas development in the Qiongdongnan Basin,South China Sea has initiated the need to evaluate submarine debris-flow hazard risks to seafloor infrastructures.This paper presents a case study on evaluating the debris-flow hazard risks to the planned pipeline systems in this region.We used a numerical model to perform simulations to support this quantitative evaluation.First,one relict failure interpreted across the development site was simulated.The back-analysis modeling was used to validate the applicability of the rheological parameters.Then,this model was applied to forecast the runout behaviors of future debris flows originating from the unstable upslope regions considered to be the most critical to the pipeline systems surrounding the Manifolds A and B.The model results showed that the potential debris-flow hazard risks rely on the location of structures and the selection of rheological parameters.For the Manifold B and connected pipeline systems,because of their remote distances away from unstable canyon flanks,the potential debris flows impose few risks.However,the pipeline systems around the Manifold A are exposed to significant hazard risks from future debris flows with selected rheological parameters.These results are beneficial for the design of a more resilient pipeline route in consideration of future debris-flow hazard risks.

Submarine volcanism in the southern margin of the South China Sea

Submarine volcanism is widely developed in the South China Sea(SCS).However,the characteristics,distribution,and genesis of submarine volcanoes in the southern margin of the SCS remain obscure.In this study,we analyzed the characteristics of submarine volcanoes and identified a total of 43 submarine volcanoes in the southern margin of the SCS,based on a newly acquired 310-km seismic reflection profile,along with previous 45 multi-channel seismic(MCS)profiles,petrological results from volcanic rocks sampled by dredging and drilling,nearby ocean bottom seismometer(OBS)wide-angle seismic profiles,and gravity and magnetic data.The study ascertains that most of these volcanoes are located in fault-block belts and graben-horst zones with strong crustal stretching and thinning.These volcanoes exhibit positive high-amplitude external seismic reflections,weak and chaotic internal seismic reflections,and are accompanied by local deformation of the surrounding sedimentary strata.Meanwhile,they have higher positive gravity anomalies and higher magnetic anomalies than the background strata.The petrological dating results show that volcanic ages are primarily in the Pliocene-Pleistocene,with geochemical characteristics indicating dominance of oceanic island basalt(OIB)-type alkali-basalts.Extensional faults have obviously spatial correspondence with post-spreading volcanism,suggesting these faults may provide conduits for submarine volcanism.The high-velocity bodies(HVBs)in the lower crust and magma underplating exist in the southern SCS,which could provide a clue of genesis for submarine volcanism.The inference is that the intensity of post-spreading volcanism in the southern margin might be affected by stretching faults,crustal thinning and magma underplating.

Late Eocene–early Miocene provenance evolution of the Crocker Fan in the southern South China Sea

There are many large-scale Cenozoic sedimentary basins with plentiful river deltas,deep-water fans and carbonate platforms in the southern South China Sea.The Crocker Fan was deposited as a typical submarine fan during the late Eocene–early Miocene,and stretches extensively across the entire Sarawak–Sabah of the northern Borneo area.However,systematic analyses are still lacking regarding its sediment composition and potential source suppliers.No consensus has been reached yet on the provenance evolution and sedimentary infilling processes,which seriously impeded the oil-and-gas exploration undertakings.By combining with sedimentaryfacies identification,heavy mineral assemblages,elemental geochemistry and detrital zircon U-Pb dating,this paper aims to generalize an integrated analysis on the potential provenance terranes and restore source-to-sink pathways of the Crocker Fan.In general,the Crocker Fan was initially formed over the Cretaceous–lower/middle Eocene Rajang Group by an angular Rajang unconformity.The continual southward subduction of the protoSouth China Sea resulted in magmatic activities and subsequent regional deformation and thrusting along the Lupar Line in the northern Borneo.The lowermost Crocker sequence is featured by a thick conglomerate layer sourced from in-situ or adjacent paleo-uplifts.From the late Eocene to the early Miocene,the Crocker Fan was constantly delivered with voluminous detritus from the Malay Peninsula of the western Sundaland.The Zengmu Basin was widely deposited with delta plain and neritic facies sediments,while the Brunei-Sabah Basin,to the farther east,was ubiquitously characterized by turbiditic sequences.The Crocker Fan successions are overall thick layers of modest-grained sandstones,which formed high-quality reservoirs in the southern South China Sea region.

Experimental and numerical analysis on suitability of S-Glass-Carbon fiber reinforced polymer composites for submarine hull

Suitability of S-Glass/carbon fiber reinforced polymer composite for submarine hull subjected to hydrostatic pressure has been investigated in the present study.Metallic materials have raised concerns owing to their decomposition due to low resistance towards salinity and hence polymer composites have been explored to showcase their mechanical stability to withstand transverse and impact loads.To this end,the mechanical properties of S-Glass/carbon fiber reinforced polymer composite were experimentally investigated and higher specific strength and stiffness of the composite in comparison to many metallic materials used for submarine hull were reported.The obtained experimental values were used for the static and dynamic crash analysis of the bow,stern and foil through Finite Element Analysis(FEA);where depth of travel was varied from sea surface level of 0-7000 m.Submarine assembly was later developed with the optimum shape and thickness of each part.We also report the nonlinear crash analysis upon impact at velocity ranging from 3 to 21 m/s.Besides,kinetic energy,acceleration peak and internal energy in struck submarine revealed that travel depth 1750 m and 3500 m is recommendable,more particularly,crash safety factor of the submarine is found to be within limit when submarine encounters crash at 1750 m.

Morphometric analysis of the Andaman outer shelf and upper slope——Implications for the recent slope failure events

The devastating 2004 tsunamis that hit the southwestern coast of Thailand pose a serious threat to people along the coastal zone. A major aim for the tsunami hazard prediction is better prediction of the next tsunamis and their impacts. In this paper, we present the first implications of recent slope failure events of the Andaman outer shelf and upper slope based on a new detailed bathymetric data and subbottom profiler records acquired during two cruises of the MASS project in 2006 and 2007. Morphometric analysis reveals a variety of anomalous features,including: three large plateaus surrounded by moats, ruggedness and unevenness of slope morphology, and two translational submarine landslides. Two submarine landslides are studied from the detailed bathymetric data and subbottom profiler record covering the upper slope of the Andaman Sea shelf break within Thai exclusive economic zone. Maximum approximated volumes of both displaced masses are 4.8×10~7 m~3 and 2.2×10~7 m~3.Considering the data, there is no evidence that landslides have been the sources for tsunami hazard potential in recent geological time. These prerequisites will allow better study of slope failure events in the area. Further investigation is required to better understand obvious geotectonic phenomena.

Origin of submarine canyon-channel systems along the middle segment of West Mariana Ridge,Philippine Sea

Submarine canyon-channel systems have been documented in the Parece Vela Basin,West Mariana Ridge;however,the mechanism of the formation and controlling factors remain poorly understood.Based on high-resolution multibeam bathymetric data and two-dimensional(2D)seismic profiles,we identified and mapped the submarine canyon-channel system along the middle segment of West Mariana Ridge in the Philippine Sea.These submarine canyon-channels show a main W-E orientation at depth of 2000–4500 m.They are approximately 72–128 km in length and 1.3–15 km in width,and their canyon heads are adjacent to the seamounts with several branches.The upper reaches of submarine canyon-channels are characterized by deeply incised,narrow,V-shaped thalwegs,suggesting the powerful erosion of gravity flows.The distinguished sediment waves are suggested to be resulted from the interaction of turbidity currents and seafloor.Our observations demonstrate that gravity flows originated from the collapses of seamount flanks plays a vital role in developing the submarine canyonchannel system along the West Mariana Ridge.This work provides better understanding of erosion,transport,and deposition of sediments from subducting ridges to deep-water basins,and also new insights into the origin and evolution of submarine canyon-channel systems along subducting ridges.

Numerical Study on Lateral Buckling Mode of Pipelines Laid on A Sleeper

Because non-buried submarine pipelines under cyclic thermal loading are prone to global buckling,sleepers are commonly laid along the pipeline route to induce a series of relatively small and controllable lateral buckling.A finite element model which can simulate the transformation of pipeline laid on a sleeper from vertical buckling to lateral buckling is established in this work.The parameters of sleeper affecting pipeline buckling modes are analysed,and a new kind of sleeper is proposed aimed at avoiding antisymmetric buckling.Results show that the lateral trigger force can avoid antisymmetric lateral buckling when acting between 1℃and 13℃before the critical buckling temperature.The range increases slightly with increasing trigger force.Compared with an ordinary sleeper,the proposed new sleeper with slider can reduce the critical buckling temperature by 25%,which significantly improves the success rate of sleepers.

Spatial distribution and export of nutrients and metal elements in the subterranean estuary of Daya Bay

Subterranean estuaries(STE)are important seawater-groundwater mixing zones with complex biogeochemical processes,which play a vital role in the migration and transformation of dissolved materials.In this study,we first investigated the spatial distributions of dissolved inorganic nitrogen(DIN),dissolved inorganic phosphorous(DIP),dissolved inorganic silicon(DSi)and metal elements(As,Ba,Cr,Cu,Fe,Mn,Ni,Pb,and Zn)in STE including upper intertidal,seepage face and subtidal zones.We then estimated submarine groundwater discharge(SGD)and associated nutrient and metal element fluxes.From the generalized Darcy’s law method,SGD was estimated to be 30.13 cm/d,which was about 7 times larger than the inflow(4.16 cm/d).The nutrient and metal fluxes from SGD were estimated to be(5.33±4.99)mmol/(m^(2)·d)for DIN,(0.22±0.03)mmol/(m^(2)·d)for DIP,(16.20±2.05)mmol/(m^(2)·d)for DSi,(1325.06±99.10)μmol/(m^(2)·d)for Fe,(143.41±25.13)μmol/(m^(2)·d)for Mn,(304.06±81.07)μmol/(m^(2)·d)for Zn,(140.21±13.33)μmol/(m^(2)·d)for Cu,(84.49±2.94)μmol/(m^(2)·d)for Pb,(37.38±5.51)μmol/(m^(2)·d)for Ba,(27.88±3.89)μmol/(m^(2)·d)for Cr,(10.10±6.33)μmol/(m^(2)·d)for Ni,and(6.25±3.45)μmol/(m^(2)·d)for As.The nutrient and metal fluxes from SGD were relatively higher than those from the inflow,suggesting that nearshore groundwater acted as the sources of nutrients and metal elements discharging into the sea.The environmental potential pollution of coastal seawater was evaluated by pollution factor index(Pi),comprehensive water quality index(CWQI),and ecological risk index(ERI).Pb mainly caused potential danger of nearshore environment with considerable contamination(Pi=5.78±0.19),heavy pollution(CWQI=4.09)and high ecological risk(ERI=18.00).This study contributed to better understanding the behavior of nutrients and metal elements and improving the sustainable management of STE under the pressure of anthropogenic activities and climate change.

Vortex-Induced Vibration Response Features of A Submarine Multi-Span Pipeline via Towing Tank Experimental Tests

In offshore engineering, the phenomenon of free span often occurs, and the pipeline may have multiple free spans adjacent to each other, forming a multi-span pipeline. The interaction of different spans makes the structural vibration characteristics more complex, which may change the fatigue characteristics of the pipeline and affect the safety of the structure. In this paper, model tests were designed to explore the vortex-induced vibration(VIV) characteristics of multi-span pipelines and investigate the multi-span interaction mechanism. The experimental study mainly focused on the dynamic response of double-span pipelines, and further extended to triple-span pipelines, hoping that the results can be applied to more complex environment. The effects of span-length ratio, buried depth and axial force on VIV of the pipeline were investigated and discussed. The dynamic response of the pipeline varied with the span length. There was obvious interaction between different spans of multi-span pipelines, and the pipe-sediment interaction obviously affected the vibration characteristics of pipeline. The differences of pipeline burial depth and axial force changed the structural stiffness. With the increase of buried depth, the response amplitude presented a downward trend. The spanwise evolutions were asymmetric caused by the pipe-sediment interaction and multi-span interaction. The results can help to identify multi-span pipelines in engineering, and realize the prevention and control of free spans.

Using Rn-222 to Study Human-Regulated River Water-Sediment Input Event in the Estuary

The implementation of the water sediment regulation scheme(WSRS)is a typical example of artificially controlling land-source input.During WSRS,the water discharge of the Yellow River will increase significantly,and so will the input of terri-genous materials.In this study,we used a natural geochemical tracer 222Rn to quantify terrestrial inputs under the influence of the 2014 WSRS in the Yellow River Estuary.The results indicated that during WSRS the concentration of 222Rn in the estuary increased by about four times than in the period before WSRS.The high-level 222Rn plume disappeared quickly after WSRS,indicating that 222Rn has a very short‘memory effect’in the estuary.Based on the investigation conducted from 2015 to 2016,the concentration of 222Rn tended to be stable in the lower reaches of the Yellow River.During WSRS,the concentrations of 222Rn in the river water in-creased sharply at about 3–5 times greater than in the non-WSRS period.Based on the 222Rn mass balance model,the fluxes of 222Rn caused by submarine groundwater discharge(SGD)were estimated to be(3.5±1.7)×10^(3),(11±3.9)×10^(3),and(5.2±1.9)×10^(3)dpm m^(-2)d^(-1)in the periods before,during,and after WSRS,respectively.This finding indicated that SGD was the major source of 222Rn in the Yellow River Estuary,which can be significantly increased during WSRS.Furthermore,the SGD-associated nutrient fluxes were estimated to be 9.8×10^(3),2.5×102,and 1.1×10^(4)μmolm^(-2)d^(-1)for dissolved inorganic nitrogen,phosphorus,and silicon,respectively,during WSRS or about 2–40 times greater than during the non-WSRS period.

Theoretical and Numerical Studies on the Coupling Deformation of Global Lateral Buckling and Walking of Submarine Pipeline

Buckling initiation devices/techniques,including sleepers,distributed buoyancy,snake lay,and residual curvature method(RCM),have recently been widely applied in engineering.These initiated buckles may induce a long pipeline to transform into multiple short pipeline segments,which promote the occurrence of pipeline walking.Thus,a pipeline,which is designed to buckle laterally,may laterally and axially displace over time when subjected to repeated heating and cooling cycles.This study aims to reveal the coupling mechanism of pipeline walking and global lateral buckling.First,an analytic solution is proposed to estimate the walking of pipeline segments between two adjacent buckles.Then,the sensitivity of this method to heating and cooling cycles is analyzed.Results show the applicability of the proposed walking analytical solution of buckling pipelines.Subsequently,an influence analysis of walking on global buckling,including the capacity of buckling initiation,buckling amplitude,buckling mode,and failure assessment of the buckling pipeline,is performed.The results reveal that the effect of walking on the buckling axial force is negligible.However,pipeline walking will aggravate the asymmetry of the pipeline buckling and the failure parameters of the pipeline during the post-buckling.

Slope Instability Analysis of the Qiongdongnan Basin in the Northern Part of the South China Sea:Implications for the Risk Evaluation of Deepwater Drilling

The instability of continental slopes damages marine engineering equipment,such as submarine pipelines,resulting in the generation of tsunamis,which endangers the safety of nearshore personnel.Therefore,research on the instability of continental slopes where submarine landslides usually occur is crucial to the risk evaluation of deepwater drilling.Previous studies were mainly based on simplified 2D and 3D models,which extend the 2D model applied on submarine slopes with complex topography.In this study,a numerical model with bathymetric data from the Qiongdongnan Basin was established.Furthermore,3D slope stability analysis and static and dynamic analyses were conducted.The static analysis found two discussions where slopes are most likely to occur.Through the analysis of different seismic forces,the dynamic result showed that an instability area is added to the two positions where the static analysis is unstable.Topography scatters and transmits seismic waves and controls the accumulation and diffusion of seismic energy.3D calculations and analysis revealed that the direction of slope instability is closely related to terrain inclination,slope,terrain effect,and terrain curvature.Data showed that instability situations could not be derived from a single direction or profile data.Such situations are an important factor in slope stability analysis and are critical to the prediction and evaluation of marine geological disasters.