As a core functional refractory in the continuous casting process,the service reliability of the submerged entry nozzle(SEN)is directly related to the stability of continuous casting production,the quality of casting ...As a core functional refractory in the continuous casting process,the service reliability of the submerged entry nozzle(SEN)is directly related to the stability of continuous casting production,the quality of casting billets,and production efficiency.Al_(2)O_(3) inclusions clogging constitutes the predominant failure mode of SEN,particularly during continuous casting of high-grade steels.Although several studies in the literature have demonstrated that electric field application can mitigate SEN clogging to some extent,the underlying mechanism remains poorly understood,which hinders its widespread acceptance and practical implementation.The mechanism of preventing SEN clogging by applying a positive electric field was studied,and experimental verification was conducted on it in a certain steel plant.The results indicate that Al_(2)O_(3) inclusions exhibit a positive charge in molten steel under high-temperature(~1600℃)and low-oxygen-partial-pressure(≤20×10-6)conditions.In the continuous casting process at a Chinese steel plant,applying a positive electric field to the SEN effectively suppressed the migration of Al_(2)O_(3) inclusions toward the SEN wall,significantly enhancing its clogging resistance.展开更多
The reaction of carbon-free oxide-based(corundum,spinel,zirconia,and mullite)submerged entry nozzle(SEN)lining with rare earth inclusions and its anti-clogging effects under near working conditions were systematically...The reaction of carbon-free oxide-based(corundum,spinel,zirconia,and mullite)submerged entry nozzle(SEN)lining with rare earth inclusions and its anti-clogging effects under near working conditions were systematically studied.A variety of lining composite test methods were innovatively used to ensure the consistency of test conditions.The experimental results showed that the mullite(acidic oxide)has strong reactivity with rare earth inclusions,and the spinel(basic oxide)has stable chemical properties and weak reactivity with rare earth inclusions.Because alumina is one of the main reactants of clogging formation,corundum is not suitable for SEN lining.There are less clogs on the surface of zirconia,but it will be exsoluted and unstable.Therefore,solving the problem of zirconia exsolution will greatly strengthen its application in SEN lining.展开更多
Under submerged conditions, compared with traditional self-excited oscillating pulsed waterjets(SOPWs), annular fluid-enhanced self-excited oscillating pulsed waterjets(AFESOPWs) exhibit a higher surge pressure throug...Under submerged conditions, compared with traditional self-excited oscillating pulsed waterjets(SOPWs), annular fluid-enhanced self-excited oscillating pulsed waterjets(AFESOPWs) exhibit a higher surge pressure through self-priming. However, their pressure frequency and cavitation characteristics remain unclear, resulting in an inability to fully utilize resonance and cavitation erosion to break coal and rock. In this study, high-frequency pressure testing, high-speed photography, and large eddy simulation(LES) are used to investigate the distribution of the pressure frequency band, evolution law of the cavitation cloud, and its regulation mechanism of a continuous waterjet, SOPW, and AFESOPW. The results indicated that the excitation of the plunger pump, shearing layer vortex, and bubble collapse corresponded to the three high-amplitude frequency bands of the waterjet pressure. AFESOPWs have an additional self-priming frequency that can produce a larger amplitude under a synergistic effect with the second high-amplitude frequency band. A better cavitation effect was produced after self-priming the annulus fluid, and the shedding frequency of the cavitation clouds of the three types of waterjets was linearly related to the cavitation number. The peak pressure of the waterjet and cavitation erosion effect can be improved by modulating the waterjet pressure oscillation frequency and cavitation shedding frequency.展开更多
Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,...Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,including bubble,electromagnetic stirring,filtration separation,fluid flow,and sedimentation,often struggle with the removal of fine inclusions.Apart from these known methods,pulsed electric current(PEC),as an emerging technology,has demonstrated immense potential and environmental advantages.PEC offers adjustable current parameters and simple equipment,making it an attractive alternative to traditional methods.Its green energy-saving features and excellent results in regulating inclusion morphology and migration,as well as inhibiting submerged entry nozzle(SEN)clogging,make it a promising technology.In comparison to continuous current technology,PEC has shown significant advantages in regulating inclusions,not only improving purification efficiency but also demonstrating outstanding performance in flow stability and energy consumption.The ability of PEC to efficiently reduce inclusion numbers enhances the purity and quality of molten steel,improving its mechanical properties.Currently,the theoretical basis for controlling the movement of inclusions by current is mainly composed of three major theories:the double electric layer theory,electromagnetic force reverse separation theory,and electric free energy drive theory.These theories together form an important framework for researchers to understand and optimize the behavior of impurity movement controlled by electric current.Looking ahead,PEC is expected to pave the way for new solutions in directional regulation of inclusion migration,efficient inclusion removal,SEN clogging prevention,and the purification of molten steel.展开更多
Various technologies and projects have been explored and developed for the synergetic control of environmental pollution and carbon emissions in aquatic ecosystems.Planting submerged vegetation in shallow waters was a...Various technologies and projects have been explored and developed for the synergetic control of environmental pollution and carbon emissions in aquatic ecosystems.Planting submerged vegetation in shallow waters was also expected to achieve this purpose.However,the magnitude and mechanism of carbon dioxide(CO_(2))emission affected by submerged vegetation is not clear enough in complex aquatic ecosystems.This study investigated the influences of submerged plants on CO_(2)emission,ecosystem metabolism features,and microbial community traits based on observations in river networks on the Changjiang River Delta.The results showed that CO_(2)emission from planted waters accounted for 73%of unplanted waters.Meanwhile,planted waters had higher dissolved organic carbon removal capacity in overlying water and higher potential of carbon sequestration in sediment at the same time.These distinctions between the two habitats were attributed to(1)improved CO_(2)and bicarbonate consumption in water columns via enhancing photosynthesis and(2)inhibited CO_(2)production by reconstructing the benthic microbial community.Additional eco-advantages were found in planted sediments,such as a high potential of methane oxidation and xenobiotics biodegradation and a low risk of becoming black and odorous.In brief,submerged vegetation is beneficial in promoting pollution removal and carbon retention synchronously.This study advances our understanding of the feedback between aquatic metabolism and CO_(2)emission.展开更多
The optimization of deposited metal properties through the addition of rare earth elements to welding materials was explored.Utilizing optical microscope,scanning electron microscope,energy dispersive spectroscope,and...The optimization of deposited metal properties through the addition of rare earth elements to welding materials was explored.Utilizing optical microscope,scanning electron microscope,energy dispersive spectroscope,and X-ray diffractometer,combined with software tools like Matlab,Image-Pro Plus,and CHANNEL5,the influence mechanism of rare earth element addition on the strength,toughness,and inclusions of deposited metal in 1000 MPa grade high-strength steel was investigated.The results indicate that the incorporation of rare earth elements enhances the weldability of the welding materials.With the addition of rare earth elements,the tensile strength of the deposited metal increases from 935 MPa to 960 MPa.However,further addition leads to a decrease in tensile strength,while the yield strength continuously increases by 8.5%-17.2%.The addition of appropriate amounts of rare earth elements results in an increase in acicular ferrite and retained austenite content,as well as grain refinement in the deposited metal,leading to 8.5%-24.3% and 15.6%-42.2% enhancement in impact energy at−40℃ and−60℃,respectively.Additionally,the proper addition of rare earth elements modifies the inclusions and generates fine and dispersed composite inclusions that bond better with the matrix,thereby optimizing the properties of the deposited metal through various mechanisms.Adding an appropriate amount of rare earth elements can significantly enhance the properties of the deposited metal in 1000 MPa grade high-strength steel,and improve the match between high strength and toughness,meeting the demands for high-strength steel used in hydropower applications.展开更多
The finite volume method was applied to numerically simulate the bottom pressure field induced by regular waves,vehicles in calm water and vehicles in regular waves.The solution of Navier-Stokes(N-S)equations in the v...The finite volume method was applied to numerically simulate the bottom pressure field induced by regular waves,vehicles in calm water and vehicles in regular waves.The solution of Navier-Stokes(N-S)equations in the vicinity of numerical wave tank's boundary was forced towards the wave theoretical solution by incorporating momentum source terms,thereby reducing adverse effects such as wave reflection.Simulations utilizing laminar flow,turbulent flow,and ideal fluid models were all found capable of effectively capturing the waveform and bottom pressure of regular waves,agreeing well with experimental data.In predicting the bottom pressure field of the submerged vehicle,turbulent simulations considering fluid viscosity and boundary layer development provided more accurate predictions for the stern region than inviscid simulations.Due to sphere's diffractive effect,the sphere's bottom pressure field in waves is not a linear superposition of the wave's and the sphere's bottom pressure field.However,a slender submerged vehicle exhibits a weaker diffractive effect on waves,thus the submerged vehicle's bottom pressure field in waves can be approximated as a linear superposition of the wave's and the submerged vehicle's bottom pressure field,which simplifies computation and analysis.展开更多
This study investigates the effects of radiation force due to the rotational pitch motion of a wave energy device,which comprises a coaxial bottom-mounted cylindrical caisson in a two-layer fluid,along with a submerge...This study investigates the effects of radiation force due to the rotational pitch motion of a wave energy device,which comprises a coaxial bottom-mounted cylindrical caisson in a two-layer fluid,along with a submerged cylindrical buoy.The system is modeled as a two-layer fluid with infinite horizontal extent and finite depth.The radiation problem is analyzed in the context of linear water waves.The fluid domain is divided into outer and inner zones,and mathematical solutions for the pitch radiating potential are derived for the corresponding boundary valve problem in these zones using the separation of variables approach.Using the matching eigenfunction expansion method,the unknown coefficients in the analytical expression of the radiation potentials are evaluated.The resulting radiation potential is then used to compute the added mass and damping coefficients.Several numerical results for the added mass and damping coefficients are investigated for numerous parameters,particularly the effects of the cylinder radius,the draft of the submerged cylinder,and the density proportion between the two fluid layers across different frequency ranges.The major findings are presented and discussed.展开更多
Submerged arc welding(SAW)is a highly efficient welding technique that is well suited to joining thick materials due to its ability to achieve high deposition rates.Its reliability and scalability make it widely appli...Submerged arc welding(SAW)is a highly efficient welding technique that is well suited to joining thick materials due to its ability to achieve high deposition rates.Its reliability and scalability make it widely applicable across various industries.This paper presents an innovative method to enhance the mechanical properties of weld metal by incorporating manganese-functionalized boehmite nanoparticles into the SAW process.The research systematically investigates the influence of welding parameters—arc voltage,current,electrode stick-out,welding speed,and nanoparticle-layer thickness—on the hardness and microstructure of the weld zone in St37 steel.The findings reveal that the inclusion of manganese-adsorbed boehmite nanoparticles significantly improves weld-zone performance.Under the welding-arc heat,these nanoparticles decompose into aluminum oxide and manganese oxide,contributing to increased hardness and mechanical strength while promoting notable grain refinement.This transformation alters the weld microstructure from coarse ferrite to fine acicular ferrite,improving toughness and resilience.Using response surface methodology,optimal welding parameters are identified,with hardness as the primary response variable.The results show that higher welding speeds and greater electrode stick-out increase hardness,while excessive arc voltage and current lead to grain coarsening and reduced hardness.The presence of nanoparticles further increases hardness,achieving a peak value of 152.15 HV(Vickers hardness)with a 1-mm-thick nanoparticle layer compared to a baseline hardness of-140 HV in nanoparticle-free samples.Microstructural analysis confirms a roughly 30%reduction in grain size,highlighting the critical role of nanoparticles in refining microstructure and enhancing the mechanical properties of the weld.展开更多
The reservoir landslide is typically characterized by high-speed movement of a particle-fluid mixture,and its flow and deposit mechanisms are complex.This paper presents the mechanism of submerged granular column coll...The reservoir landslide is typically characterized by high-speed movement of a particle-fluid mixture,and its flow and deposit mechanisms are complex.This paper presents the mechanism of submerged granular column collapse under different densities ambient fluids based on coupled computational fluid dynamics and discrete element method(CFD-DEM)analysis.Important fluid-particle interaction forces,such as the drag force and the buoyancy,are considered by exchanging interaction forces between the CFD and DEM computations.We focus on the flow and deposit characteristics of submerged granular column collapse,namely the runout distance,the tail end height,the particle velocity,the energy,and deposit morphology,which are analyzed qualitatively and quantitatively.The change in fluid field caused by submerged granular column collapse and the formation of eddies are also discussed.A relatively dense fluid can significantly hinder the motion of granular flow,but can improve the conversion efficiency of kinetic energy from the vertical to the horizontal direction.Moreover,the eddies caused by fluid turbulence erode the surface of the granular pile,which is especially marked in a high-density fluid.The findings can provide vital theoretical support for the flow and deposit characteristics of granular flow under fluid and offer insights for the study of reservoir landslides.展开更多
To assess the population development of submerged plant species in disturbed lake ecosystems,we need to better understand the genetic diversity and spatial genetic structure at a fine scale,as well as the impact of di...To assess the population development of submerged plant species in disturbed lake ecosystems,we need to better understand the genetic diversity and spatial genetic structure at a fine scale,as well as the impact of disturbances on the populations.Caohai Lake,in southwest China,is a suitable natural sampling lake because of its abundance of submerged plants and the intense human disturbance.Three widely distributed species,Potamogeton lucens,Ceratophyllum demersum,and Myriophyllum spicatum,were sampled;the spatial position of each individual was recorded in two-dimensional coordinates;and the species were analyzed genetically using microsatellite markers.Among the species studied,M.spicatum exhibited the highest genetic and clonal diversities.All P.lucens subpopulations but one showed a significant fine-scale spatial genetic structure(FSGS),which may result from the limited gene dispersal.However,M.spicatum and C.demersum,with a relatively large distance of gene dispersal,had no significant FSGS.The FSGS pattern of P.lucens at the dock site with intense boat disturbance was significantly different from that at other sites.Our results imply that the FSGS of submerged plants is affected by many factors including seed dispersal,vegetative reproduction and disturbance from birds and boats.Most subpopulations of the three species hadσ_(sex)^(2)/σ_(veg)^(2)values greater than one,implying that the sexual dispersal contributes more than vegetative dispersal to total gene dispersal.Therefore,it is worth paying attention to the importance of seed dispersal for population development of submerged plants in lake ecosystems.展开更多
Taking a C1x motor with a backward-facing step which can generate a typical corner vortex as a reference,a numerical methodology using large eddy simulation was established in this study.Based on this methodology,the ...Taking a C1x motor with a backward-facing step which can generate a typical corner vortex as a reference,a numerical methodology using large eddy simulation was established in this study.Based on this methodology,the position of the backward-facing step of the motor was computed and analyzed to determine a basic configuration.Two key geometrical parameters,the head cavity angle and submerged nozzle cavity height,were subsequently introduced.Their effects on the corner vortex motion and their interactions with the acoustic pressure downstream of the backward-facing step were analyzed.The phenomena of vortex acoustic coupling and characteristics of pressure oscillations were further explored.The results show that the maximum error between the simulations and experimental data on the dominant frequency of pressure oscillations is 5.23%,which indicates that the numerical methodology built in this study is highly accurate.When the step is located at less than 5/8 of the total length of the combustion chamber,vortex acoustic coupling occurs,which can increase the pressure oscillations in the motor.Both the vorticity and the scale of vortices in the downstream step increase when the head cavity angle is greater than 24°,which increases the amplitude of the pressure oscillation by maximum 63.0%.The submerged nozzle cavity mainly affects the vortices in the cavity itself rather than those in the downstream step.When the height of the cavity increases from 10 to 20 mm,the pressure oscillation amplitude under the main frequency increases by 39.1%.As this height continues to increase,the amplitude of pressure oscillations increases but the primary frequency decreases.展开更多
Submerged Abrasive Waterjet Peening(SAWJP)shows great application potential in augmenting the fatigue properties of metallic parts.Thus,the present work aims to investigate the influence of SAWJP on the Surface Integr...Submerged Abrasive Waterjet Peening(SAWJP)shows great application potential in augmenting the fatigue properties of metallic parts.Thus,the present work aims to investigate the influence of SAWJP on the Surface Integrity(SI)and Fretting Fatigue(FF)properties of Inconel 718(IN718)superalloy and illustrate the microstructural evolution,FF life improvement,and fretting wear mechanism.First,the SI of the IN718 specimen was examined following treatment via SAWJP.Results showed that the specimen subjected to SAWJP formed a total plastic deformation layer of 56μm.The maximum microhardness and Compressive Residual Stress(CRS)measured across the depth of the SAWJP-treated specimens exhibited an increase in values ranging between 522 HV and 541 HV and 1171–1380 MPa,respectively.The FF test results of the specimen before and after SAWJP treatment at ambient temperatures indicated that the FF life of the SAWJP-treated specimen surpassed that of the as-received specimen by a factor of 2.81.The examination of the FF fracture,contact surface,and crack propagation behavior revealed the crucial factors contributing to the enhanced FF resistance of the IN718 specimen,including the gradient nanostructure characterized by ultra-refined grains,substantial CRS,and elevated microhardness,which were all induced by the SAWJP treatment.展开更多
The large molecular weight and high hydrophilicity of chloramphenicol(CAP) residuals in wastewater led to severe degradation difficulty,which propelled the development of new wastewater degradation processes and react...The large molecular weight and high hydrophilicity of chloramphenicol(CAP) residuals in wastewater led to severe degradation difficulty,which propelled the development of new wastewater degradation processes and reactors based on process intensification.This study enhanced the CAP degradation by ozone/peroxydisulfate(PDS) advanced oxidation process in a submerged rotating packed bed(SRPB)reactor.Compared the usage of different oxidants,it was indicated that the combination of O_(3) and PDS exhibited a higher degradation efficiency than ozone and PDS alone.The more desired degradation efficiency could be achieved at the operating conditions of ascending PDS concentration,SRPB rotational speed,ozone concentration,reduced initial CAP concentration,and the water qualities of ascended pH,lower Cl^(-)and initial CO_(3)^(2-) concentrations.Under the optimized conditions of C_(CAP)=20 mg·L^(-1),C_(O3)=30 mg·L^(-1),C_(PDS)=100 mg·L^(-1),and N=400 r·min^(-1),and water qualities of pH=10,the maximum chloramphenicol degradation efficiency of 97% and kinetic constant of 0.23 min^(-1) were achieved after treating 16 min.A comparison of the results with previously reported advanced oxidation processes of CAP indicated that the enhanced O^(3)/PDS advanced oxidation system using the SRPB can significantly improve the degradation efficiency of CAP.展开更多
This study introduces an enhanced adaptive fractional-order nonsingular terminal sliding mode controller(AFONTSMC)tailored for stabilizing a fully submerged hydrofoil craft(FSHC)under external disturbances,model uncer...This study introduces an enhanced adaptive fractional-order nonsingular terminal sliding mode controller(AFONTSMC)tailored for stabilizing a fully submerged hydrofoil craft(FSHC)under external disturbances,model uncertainties,and actuator saturation.A novel nonlinear disturbance observer modified by fractional-order calculus is proposed for flexible and less conservative estimation of lumped disturbances.An enhanced adaptive fractional-order nonsingular sliding mode scheme augmented by disturbance estimation is also introduced to improve disturbance rejection.This controller design only necessitates surpassing the estimation error rather than adhering strictly to the disturbance upper bound.Additionally,an adaptive fast-reaching law with a hyperbolic tangent function is incorporated to enhance the responsiveness and convergence rates of the controller,thereby reducing chattering.Furthermore,an auxiliary actuator compensator is developed to address saturation effects.The resultant closed system of the FSHC with the designed controller is globally asymptotically stable.展开更多
Using linear water wave theory,three-dimensional problems concerning the interaction of waves with spherical structures in a fluid which contains a three-layer fluid consisting of a layer of finite depth bounded above...Using linear water wave theory,three-dimensional problems concerning the interaction of waves with spherical structures in a fluid which contains a three-layer fluid consisting of a layer of finite depth bounded above by freshwater of finite depth with free surface and below by an infinite layer of water of greater density are considered.In such a situation timeharmonic waves with a given frequency can propagate with three wavenumbers.The sphere is submerged in either of the three layers.Each problem is reduced to an infinite system of linear equations by employing the method of multipoles and the system of equations is solved numerically by standard technique.The hydrodynamic forces(vertical and horizontal forces)are obtained and depicted graphically against the wavenumber.When the density ratio of the upper and middle layer is made to approximately one,curves for vertical and horizontal forces almost coincide with the corresponding curves for the case of a two-layer fluid with a free surface.This means that in the limit,the density ratio of the upper and middle layer goes to approximately one,the solution agrees with the solution for the case of a two-layer fluid with a free surface.展开更多
Based on the introduction of characteristics and ecological habits as mesophilia,photophilia,and certain ability of cold resistance of Hydrilla verticillata,the main points of its landscape application,especially on t...Based on the introduction of characteristics and ecological habits as mesophilia,photophilia,and certain ability of cold resistance of Hydrilla verticillata,the main points of its landscape application,especially on the two aspects of its planting and disposing,are discussed in a detailed way.Hydrilla verticillata can be planted in two ways,that is,directly planted into the bottom of the water,or bound with five or six cutting segments and one small piece of stone to sink in the water.On the prospect of disposing,Hydrilla verticillata can be planted together with other submerged plants as well as be planted alone,and also be with ornamental fishes.All these means of disposing would create excellent water landscape effects.Meanwhile the problems in the planting and disposing of Hydrilla verticillata that should be careful with are analyzed with the hope of providing more sufficient and comprehensive basis for the construction of beautiful ecological water landscape.展开更多
The nozzle clogging behavior of Ti-bearing IF steel was studied by metallographic analysis,scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS）,and X-ray diffraction（XRD）.According to the exper...The nozzle clogging behavior of Ti-bearing IF steel was studied by metallographic analysis,scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS）,and X-ray diffraction（XRD）.According to the experimental results,nozzle clogging primarily appears three layers.There are a lot of large-sized iron particles in the inner layer and mainly slag phase in the middle and outer layers.The principal clog constituents of the inner layer are loose alumina cluster inclusions and granular shaped alumina inclusions,containing iron particles. The clog constituents of the middle layer are mainly dendrite alumina inclusions.The primary phases existing in nozzle clogging are FeO·TiO2 and FeO·Al2O3 besidesα-Al2O3 and a-Fe.The FeO·TiO2 phases among the deposits adhere the deposits together firmly enough to lead to the inferior castability of Ti-bearing ultra low carbon steel compared with that of Ti-free low carbon Al-killed steel.展开更多
Leaves of terrestrial and aquatic plants are home to a wide diversity of bacterial species. However, the diversity and variability of epiphytic bacteria on their submerged plant hosts remains poorly understood. We inv...Leaves of terrestrial and aquatic plants are home to a wide diversity of bacterial species. However, the diversity and variability of epiphytic bacteria on their submerged plant hosts remains poorly understood. We investigated the diversity and composition of epiphytic bacteria from two common submerged macrophytes: Vallisneria natans and Hydrilla verticillata in Taihu Lake, Jiangsu, China, using methods of terminal restriction fragment length polymorphisms (T-RFLP) and clone library analyses targeted at bacterial 16S rRNA genes. The results show that: (1) the libraries of the two waterweeds contain wide phylogenetic distribution of bacteria, and that the sequences of the two libraries can be separated into 93 OTUs (at 97% similar value); (2) Betaproteobacteria, including Burkholderiales, was the most abundant bacterial group on both plants. Cyanobacteria and Gammaproteobacteria were the second largest groups on V. natans and H. verticillata, respectively. Both clone libraries included some sequences related to those of methanotrophs and nitrogen-fixing bacteria; (3) Cluster analysis of the T-RFLP profiles showed two distinct clusters corresponding to the two plant populations. Both ANOSIM of the T-RFLP data and Libshuff analysis of the two clone libraries indicated a significant difference in epiphytic bacterial communities between the two plants. Therefore, the epiphytic bacterial communities on submerged macrophytes appear to be diverse and host-specific, which may aid in understanding the ecological functions of submerged macrophytes in general.展开更多
The results of design and experiment of a submerged semi-circular breakwater at the Yangtze estuary show that the submerged structure will be unsafe when the general empirical wave force formula for semi-circular brea...The results of design and experiment of a submerged semi-circular breakwater at the Yangtze estuary show that the submerged structure will be unsafe when the general empirical wave force formula for semi-circular breakwater is used in design. Therefore, a new calculation method for the wave forces acting on a submerged semi-circular structure is given in this paper, in which the wave force acting on the inside circumference of semi-circular arch is included, and the phase modification coefficient in the general empirical formula is adjusted as well. The new wave force calculation method has been Verified by the results of seven related physical model tests and adopted in the design of the south esturary jetty of the first stage project of Deep Channel Improvement Project of the Yangtze River Estuary, the total jetty length being 17.5 km.展开更多
基金supported by the National Outstanding Youth Science Fund Project of National Natural Science Foundation of China(No.52302031)National Natural Science Foundation of China(No.51932008).
文摘As a core functional refractory in the continuous casting process,the service reliability of the submerged entry nozzle(SEN)is directly related to the stability of continuous casting production,the quality of casting billets,and production efficiency.Al_(2)O_(3) inclusions clogging constitutes the predominant failure mode of SEN,particularly during continuous casting of high-grade steels.Although several studies in the literature have demonstrated that electric field application can mitigate SEN clogging to some extent,the underlying mechanism remains poorly understood,which hinders its widespread acceptance and practical implementation.The mechanism of preventing SEN clogging by applying a positive electric field was studied,and experimental verification was conducted on it in a certain steel plant.The results indicate that Al_(2)O_(3) inclusions exhibit a positive charge in molten steel under high-temperature(~1600℃)and low-oxygen-partial-pressure(≤20×10-6)conditions.In the continuous casting process at a Chinese steel plant,applying a positive electric field to the SEN effectively suppressed the migration of Al_(2)O_(3) inclusions toward the SEN wall,significantly enhancing its clogging resistance.
基金supported by the National Outstanding Youth Science Fund Project of National Natural Science Foundation of China(52302031)National Natural Science Foundation of China(51932008 and 51772277)Central China Thousand Talents Project(204200510011).
文摘The reaction of carbon-free oxide-based(corundum,spinel,zirconia,and mullite)submerged entry nozzle(SEN)lining with rare earth inclusions and its anti-clogging effects under near working conditions were systematically studied.A variety of lining composite test methods were innovatively used to ensure the consistency of test conditions.The experimental results showed that the mullite(acidic oxide)has strong reactivity with rare earth inclusions,and the spinel(basic oxide)has stable chemical properties and weak reactivity with rare earth inclusions.Because alumina is one of the main reactants of clogging formation,corundum is not suitable for SEN lining.There are less clogs on the surface of zirconia,but it will be exsoluted and unstable.Therefore,solving the problem of zirconia exsolution will greatly strengthen its application in SEN lining.
基金supported by the program for National Natural Science Foundation of China (Nos. 52174173, 52274188, and 52104190)the Joint Funds of the National Natural Science Foundation of China (No. U24A2091)+1 种基金The Natural Science Foundation of Henan Polytechnic University (No. B2021-2)Double FirstClass Initiative of Safety and Energy Engineering (Henan Polytechnic University) (Nos. AQ20240703 and AQ20230304)。
文摘Under submerged conditions, compared with traditional self-excited oscillating pulsed waterjets(SOPWs), annular fluid-enhanced self-excited oscillating pulsed waterjets(AFESOPWs) exhibit a higher surge pressure through self-priming. However, their pressure frequency and cavitation characteristics remain unclear, resulting in an inability to fully utilize resonance and cavitation erosion to break coal and rock. In this study, high-frequency pressure testing, high-speed photography, and large eddy simulation(LES) are used to investigate the distribution of the pressure frequency band, evolution law of the cavitation cloud, and its regulation mechanism of a continuous waterjet, SOPW, and AFESOPW. The results indicated that the excitation of the plunger pump, shearing layer vortex, and bubble collapse corresponded to the three high-amplitude frequency bands of the waterjet pressure. AFESOPWs have an additional self-priming frequency that can produce a larger amplitude under a synergistic effect with the second high-amplitude frequency band. A better cavitation effect was produced after self-priming the annulus fluid, and the shedding frequency of the cavitation clouds of the three types of waterjets was linearly related to the cavitation number. The peak pressure of the waterjet and cavitation erosion effect can be improved by modulating the waterjet pressure oscillation frequency and cavitation shedding frequency.
基金supported by the Fundamental Research Funds for the Central Universities(No.FRF-BD-23-01).
文摘Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,including bubble,electromagnetic stirring,filtration separation,fluid flow,and sedimentation,often struggle with the removal of fine inclusions.Apart from these known methods,pulsed electric current(PEC),as an emerging technology,has demonstrated immense potential and environmental advantages.PEC offers adjustable current parameters and simple equipment,making it an attractive alternative to traditional methods.Its green energy-saving features and excellent results in regulating inclusion morphology and migration,as well as inhibiting submerged entry nozzle(SEN)clogging,make it a promising technology.In comparison to continuous current technology,PEC has shown significant advantages in regulating inclusions,not only improving purification efficiency but also demonstrating outstanding performance in flow stability and energy consumption.The ability of PEC to efficiently reduce inclusion numbers enhances the purity and quality of molten steel,improving its mechanical properties.Currently,the theoretical basis for controlling the movement of inclusions by current is mainly composed of three major theories:the double electric layer theory,electromagnetic force reverse separation theory,and electric free energy drive theory.These theories together form an important framework for researchers to understand and optimize the behavior of impurity movement controlled by electric current.Looking ahead,PEC is expected to pave the way for new solutions in directional regulation of inclusion migration,efficient inclusion removal,SEN clogging prevention,and the purification of molten steel.
基金supported by the Youth Exploration Foundation of Chinese Research Academy of Environmental Sciences(No.2022YSKY-55).
文摘Various technologies and projects have been explored and developed for the synergetic control of environmental pollution and carbon emissions in aquatic ecosystems.Planting submerged vegetation in shallow waters was also expected to achieve this purpose.However,the magnitude and mechanism of carbon dioxide(CO_(2))emission affected by submerged vegetation is not clear enough in complex aquatic ecosystems.This study investigated the influences of submerged plants on CO_(2)emission,ecosystem metabolism features,and microbial community traits based on observations in river networks on the Changjiang River Delta.The results showed that CO_(2)emission from planted waters accounted for 73%of unplanted waters.Meanwhile,planted waters had higher dissolved organic carbon removal capacity in overlying water and higher potential of carbon sequestration in sediment at the same time.These distinctions between the two habitats were attributed to(1)improved CO_(2)and bicarbonate consumption in water columns via enhancing photosynthesis and(2)inhibited CO_(2)production by reconstructing the benthic microbial community.Additional eco-advantages were found in planted sediments,such as a high potential of methane oxidation and xenobiotics biodegradation and a low risk of becoming black and odorous.In brief,submerged vegetation is beneficial in promoting pollution removal and carbon retention synchronously.This study advances our understanding of the feedback between aquatic metabolism and CO_(2)emission.
基金Provincial Key Research and Development Plan of Heilongjiang(2022ZX04A01)。
文摘The optimization of deposited metal properties through the addition of rare earth elements to welding materials was explored.Utilizing optical microscope,scanning electron microscope,energy dispersive spectroscope,and X-ray diffractometer,combined with software tools like Matlab,Image-Pro Plus,and CHANNEL5,the influence mechanism of rare earth element addition on the strength,toughness,and inclusions of deposited metal in 1000 MPa grade high-strength steel was investigated.The results indicate that the incorporation of rare earth elements enhances the weldability of the welding materials.With the addition of rare earth elements,the tensile strength of the deposited metal increases from 935 MPa to 960 MPa.However,further addition leads to a decrease in tensile strength,while the yield strength continuously increases by 8.5%-17.2%.The addition of appropriate amounts of rare earth elements results in an increase in acicular ferrite and retained austenite content,as well as grain refinement in the deposited metal,leading to 8.5%-24.3% and 15.6%-42.2% enhancement in impact energy at−40℃ and−60℃,respectively.Additionally,the proper addition of rare earth elements modifies the inclusions and generates fine and dispersed composite inclusions that bond better with the matrix,thereby optimizing the properties of the deposited metal through various mechanisms.Adding an appropriate amount of rare earth elements can significantly enhance the properties of the deposited metal in 1000 MPa grade high-strength steel,and improve the match between high strength and toughness,meeting the demands for high-strength steel used in hydropower applications.
文摘The finite volume method was applied to numerically simulate the bottom pressure field induced by regular waves,vehicles in calm water and vehicles in regular waves.The solution of Navier-Stokes(N-S)equations in the vicinity of numerical wave tank's boundary was forced towards the wave theoretical solution by incorporating momentum source terms,thereby reducing adverse effects such as wave reflection.Simulations utilizing laminar flow,turbulent flow,and ideal fluid models were all found capable of effectively capturing the waveform and bottom pressure of regular waves,agreeing well with experimental data.In predicting the bottom pressure field of the submerged vehicle,turbulent simulations considering fluid viscosity and boundary layer development provided more accurate predictions for the stern region than inviscid simulations.Due to sphere's diffractive effect,the sphere's bottom pressure field in waves is not a linear superposition of the wave's and the sphere's bottom pressure field.However,a slender submerged vehicle exhibits a weaker diffractive effect on waves,thus the submerged vehicle's bottom pressure field in waves can be approximated as a linear superposition of the wave's and the submerged vehicle's bottom pressure field,which simplifies computation and analysis.
基金supported by MHRD as researcher C.K.Neog received the MHRD Institute GATE scholarship from Govt.of India.
文摘This study investigates the effects of radiation force due to the rotational pitch motion of a wave energy device,which comprises a coaxial bottom-mounted cylindrical caisson in a two-layer fluid,along with a submerged cylindrical buoy.The system is modeled as a two-layer fluid with infinite horizontal extent and finite depth.The radiation problem is analyzed in the context of linear water waves.The fluid domain is divided into outer and inner zones,and mathematical solutions for the pitch radiating potential are derived for the corresponding boundary valve problem in these zones using the separation of variables approach.Using the matching eigenfunction expansion method,the unknown coefficients in the analytical expression of the radiation potentials are evaluated.The resulting radiation potential is then used to compute the added mass and damping coefficients.Several numerical results for the added mass and damping coefficients are investigated for numerous parameters,particularly the effects of the cylinder radius,the draft of the submerged cylinder,and the density proportion between the two fluid layers across different frequency ranges.The major findings are presented and discussed.
文摘Submerged arc welding(SAW)is a highly efficient welding technique that is well suited to joining thick materials due to its ability to achieve high deposition rates.Its reliability and scalability make it widely applicable across various industries.This paper presents an innovative method to enhance the mechanical properties of weld metal by incorporating manganese-functionalized boehmite nanoparticles into the SAW process.The research systematically investigates the influence of welding parameters—arc voltage,current,electrode stick-out,welding speed,and nanoparticle-layer thickness—on the hardness and microstructure of the weld zone in St37 steel.The findings reveal that the inclusion of manganese-adsorbed boehmite nanoparticles significantly improves weld-zone performance.Under the welding-arc heat,these nanoparticles decompose into aluminum oxide and manganese oxide,contributing to increased hardness and mechanical strength while promoting notable grain refinement.This transformation alters the weld microstructure from coarse ferrite to fine acicular ferrite,improving toughness and resilience.Using response surface methodology,optimal welding parameters are identified,with hardness as the primary response variable.The results show that higher welding speeds and greater electrode stick-out increase hardness,while excessive arc voltage and current lead to grain coarsening and reduced hardness.The presence of nanoparticles further increases hardness,achieving a peak value of 152.15 HV(Vickers hardness)with a 1-mm-thick nanoparticle layer compared to a baseline hardness of-140 HV in nanoparticle-free samples.Microstructural analysis confirms a roughly 30%reduction in grain size,highlighting the critical role of nanoparticles in refining microstructure and enhancing the mechanical properties of the weld.
基金supported by the National Natural Science Foundation of China(No.51825905).
文摘The reservoir landslide is typically characterized by high-speed movement of a particle-fluid mixture,and its flow and deposit mechanisms are complex.This paper presents the mechanism of submerged granular column collapse under different densities ambient fluids based on coupled computational fluid dynamics and discrete element method(CFD-DEM)analysis.Important fluid-particle interaction forces,such as the drag force and the buoyancy,are considered by exchanging interaction forces between the CFD and DEM computations.We focus on the flow and deposit characteristics of submerged granular column collapse,namely the runout distance,the tail end height,the particle velocity,the energy,and deposit morphology,which are analyzed qualitatively and quantitatively.The change in fluid field caused by submerged granular column collapse and the formation of eddies are also discussed.A relatively dense fluid can significantly hinder the motion of granular flow,but can improve the conversion efficiency of kinetic energy from the vertical to the horizontal direction.Moreover,the eddies caused by fluid turbulence erode the surface of the granular pile,which is especially marked in a high-density fluid.The findings can provide vital theoretical support for the flow and deposit characteristics of granular flow under fluid and offer insights for the study of reservoir landslides.
基金Supported by the National Natural Science Foundation of China(No.31600325)the Self-determined Research Funds of the Central China Normal University(CCNU)from the Colleges’Basic Research and Operation of MOE(No.CCNU20TS022)。
文摘To assess the population development of submerged plant species in disturbed lake ecosystems,we need to better understand the genetic diversity and spatial genetic structure at a fine scale,as well as the impact of disturbances on the populations.Caohai Lake,in southwest China,is a suitable natural sampling lake because of its abundance of submerged plants and the intense human disturbance.Three widely distributed species,Potamogeton lucens,Ceratophyllum demersum,and Myriophyllum spicatum,were sampled;the spatial position of each individual was recorded in two-dimensional coordinates;and the species were analyzed genetically using microsatellite markers.Among the species studied,M.spicatum exhibited the highest genetic and clonal diversities.All P.lucens subpopulations but one showed a significant fine-scale spatial genetic structure(FSGS),which may result from the limited gene dispersal.However,M.spicatum and C.demersum,with a relatively large distance of gene dispersal,had no significant FSGS.The FSGS pattern of P.lucens at the dock site with intense boat disturbance was significantly different from that at other sites.Our results imply that the FSGS of submerged plants is affected by many factors including seed dispersal,vegetative reproduction and disturbance from birds and boats.Most subpopulations of the three species hadσ_(sex)^(2)/σ_(veg)^(2)values greater than one,implying that the sexual dispersal contributes more than vegetative dispersal to total gene dispersal.Therefore,it is worth paying attention to the importance of seed dispersal for population development of submerged plants in lake ecosystems.
基金Sponsored by the Natural Science Foundation of Shaanxi Province (Grant No. S2025-JC-YB-0532)the Practice and Innovation Funds for Graduate Students of Northwestern Polytechnical University (PF2024044)
文摘Taking a C1x motor with a backward-facing step which can generate a typical corner vortex as a reference,a numerical methodology using large eddy simulation was established in this study.Based on this methodology,the position of the backward-facing step of the motor was computed and analyzed to determine a basic configuration.Two key geometrical parameters,the head cavity angle and submerged nozzle cavity height,were subsequently introduced.Their effects on the corner vortex motion and their interactions with the acoustic pressure downstream of the backward-facing step were analyzed.The phenomena of vortex acoustic coupling and characteristics of pressure oscillations were further explored.The results show that the maximum error between the simulations and experimental data on the dominant frequency of pressure oscillations is 5.23%,which indicates that the numerical methodology built in this study is highly accurate.When the step is located at less than 5/8 of the total length of the combustion chamber,vortex acoustic coupling occurs,which can increase the pressure oscillations in the motor.Both the vorticity and the scale of vortices in the downstream step increase when the head cavity angle is greater than 24°,which increases the amplitude of the pressure oscillation by maximum 63.0%.The submerged nozzle cavity mainly affects the vortices in the cavity itself rather than those in the downstream step.When the height of the cavity increases from 10 to 20 mm,the pressure oscillation amplitude under the main frequency increases by 39.1%.As this height continues to increase,the amplitude of pressure oscillations increases but the primary frequency decreases.
基金financially supported by the National Key Research and Development Project,China(Nos.2018YFA0703300,2022YFB4600019)the National Natural Science Foundation of China(Nos.52275148,52405154)+2 种基金the Innovation Program Phase II of AECC Commercial Aircraft Engine Co.Ltd,China(No.HT-3RJC1053-2020)support by the Postdoctoral Fellowship Program of CPSF,China(No.GZB20240219)the Shanghai Sailing Program,China(No.24YF2708100).
文摘Submerged Abrasive Waterjet Peening(SAWJP)shows great application potential in augmenting the fatigue properties of metallic parts.Thus,the present work aims to investigate the influence of SAWJP on the Surface Integrity(SI)and Fretting Fatigue(FF)properties of Inconel 718(IN718)superalloy and illustrate the microstructural evolution,FF life improvement,and fretting wear mechanism.First,the SI of the IN718 specimen was examined following treatment via SAWJP.Results showed that the specimen subjected to SAWJP formed a total plastic deformation layer of 56μm.The maximum microhardness and Compressive Residual Stress(CRS)measured across the depth of the SAWJP-treated specimens exhibited an increase in values ranging between 522 HV and 541 HV and 1171–1380 MPa,respectively.The FF test results of the specimen before and after SAWJP treatment at ambient temperatures indicated that the FF life of the SAWJP-treated specimen surpassed that of the as-received specimen by a factor of 2.81.The examination of the FF fracture,contact surface,and crack propagation behavior revealed the crucial factors contributing to the enhanced FF resistance of the IN718 specimen,including the gradient nanostructure characterized by ultra-refined grains,substantial CRS,and elevated microhardness,which were all induced by the SAWJP treatment.
基金supported by the National Natural Science Foundation of China(22288102)。
文摘The large molecular weight and high hydrophilicity of chloramphenicol(CAP) residuals in wastewater led to severe degradation difficulty,which propelled the development of new wastewater degradation processes and reactors based on process intensification.This study enhanced the CAP degradation by ozone/peroxydisulfate(PDS) advanced oxidation process in a submerged rotating packed bed(SRPB)reactor.Compared the usage of different oxidants,it was indicated that the combination of O_(3) and PDS exhibited a higher degradation efficiency than ozone and PDS alone.The more desired degradation efficiency could be achieved at the operating conditions of ascending PDS concentration,SRPB rotational speed,ozone concentration,reduced initial CAP concentration,and the water qualities of ascended pH,lower Cl^(-)and initial CO_(3)^(2-) concentrations.Under the optimized conditions of C_(CAP)=20 mg·L^(-1),C_(O3)=30 mg·L^(-1),C_(PDS)=100 mg·L^(-1),and N=400 r·min^(-1),and water qualities of pH=10,the maximum chloramphenicol degradation efficiency of 97% and kinetic constant of 0.23 min^(-1) were achieved after treating 16 min.A comparison of the results with previously reported advanced oxidation processes of CAP indicated that the enhanced O^(3)/PDS advanced oxidation system using the SRPB can significantly improve the degradation efficiency of CAP.
基金Supported by Natural Science Basic Research Program of Shaanxi under Grant No.2023-JC-QN-0751,No.2023-JC-QN-0778Fundamental Research Funds for the Central Universities,CHD under Grant No.300102324102+1 种基金the National Natural Science Foundation of China under Grant Nos.72471035,52271313Fundamental Research Funds for the Central Universities under Grant No.XK2040021004025.
文摘This study introduces an enhanced adaptive fractional-order nonsingular terminal sliding mode controller(AFONTSMC)tailored for stabilizing a fully submerged hydrofoil craft(FSHC)under external disturbances,model uncertainties,and actuator saturation.A novel nonlinear disturbance observer modified by fractional-order calculus is proposed for flexible and less conservative estimation of lumped disturbances.An enhanced adaptive fractional-order nonsingular sliding mode scheme augmented by disturbance estimation is also introduced to improve disturbance rejection.This controller design only necessitates surpassing the estimation error rather than adhering strictly to the disturbance upper bound.Additionally,an adaptive fast-reaching law with a hyperbolic tangent function is incorporated to enhance the responsiveness and convergence rates of the controller,thereby reducing chattering.Furthermore,an auxiliary actuator compensator is developed to address saturation effects.The resultant closed system of the FSHC with the designed controller is globally asymptotically stable.
文摘Using linear water wave theory,three-dimensional problems concerning the interaction of waves with spherical structures in a fluid which contains a three-layer fluid consisting of a layer of finite depth bounded above by freshwater of finite depth with free surface and below by an infinite layer of water of greater density are considered.In such a situation timeharmonic waves with a given frequency can propagate with three wavenumbers.The sphere is submerged in either of the three layers.Each problem is reduced to an infinite system of linear equations by employing the method of multipoles and the system of equations is solved numerically by standard technique.The hydrodynamic forces(vertical and horizontal forces)are obtained and depicted graphically against the wavenumber.When the density ratio of the upper and middle layer is made to approximately one,curves for vertical and horizontal forces almost coincide with the corresponding curves for the case of a two-layer fluid with a free surface.This means that in the limit,the density ratio of the upper and middle layer goes to approximately one,the solution agrees with the solution for the case of a two-layer fluid with a free surface.
文摘Based on the introduction of characteristics and ecological habits as mesophilia,photophilia,and certain ability of cold resistance of Hydrilla verticillata,the main points of its landscape application,especially on the two aspects of its planting and disposing,are discussed in a detailed way.Hydrilla verticillata can be planted in two ways,that is,directly planted into the bottom of the water,or bound with five or six cutting segments and one small piece of stone to sink in the water.On the prospect of disposing,Hydrilla verticillata can be planted together with other submerged plants as well as be planted alone,and also be with ornamental fishes.All these means of disposing would create excellent water landscape effects.Meanwhile the problems in the planting and disposing of Hydrilla verticillata that should be careful with are analyzed with the hope of providing more sufficient and comprehensive basis for the construction of beautiful ecological water landscape.
基金supported by the National Key Technologies R&D Program of China(No.2006BAE03A06)
文摘The nozzle clogging behavior of Ti-bearing IF steel was studied by metallographic analysis,scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS）,and X-ray diffraction（XRD）.According to the experimental results,nozzle clogging primarily appears three layers.There are a lot of large-sized iron particles in the inner layer and mainly slag phase in the middle and outer layers.The principal clog constituents of the inner layer are loose alumina cluster inclusions and granular shaped alumina inclusions,containing iron particles. The clog constituents of the middle layer are mainly dendrite alumina inclusions.The primary phases existing in nozzle clogging are FeO·TiO2 and FeO·Al2O3 besidesα-Al2O3 and a-Fe.The FeO·TiO2 phases among the deposits adhere the deposits together firmly enough to lead to the inferior castability of Ti-bearing ultra low carbon steel compared with that of Ti-free low carbon Al-killed steel.
基金Supported by the National Natural Science Foundation of China(No.40730528)the National Basic Research Program of China(973Program)(No.2008CB418104)+2 种基金the Knowledge Innovation Project of Chinese Academy of Sciences(No.KZCX2-YW-JC302)the Jiangsu Provincial Science Foundation(No.BK2009024)the Frontier Foundation of Nanjing Institute of Geography & Limnology,Chinese Academy of Sciences(No.09SL021001)
文摘Leaves of terrestrial and aquatic plants are home to a wide diversity of bacterial species. However, the diversity and variability of epiphytic bacteria on their submerged plant hosts remains poorly understood. We investigated the diversity and composition of epiphytic bacteria from two common submerged macrophytes: Vallisneria natans and Hydrilla verticillata in Taihu Lake, Jiangsu, China, using methods of terminal restriction fragment length polymorphisms (T-RFLP) and clone library analyses targeted at bacterial 16S rRNA genes. The results show that: (1) the libraries of the two waterweeds contain wide phylogenetic distribution of bacteria, and that the sequences of the two libraries can be separated into 93 OTUs (at 97% similar value); (2) Betaproteobacteria, including Burkholderiales, was the most abundant bacterial group on both plants. Cyanobacteria and Gammaproteobacteria were the second largest groups on V. natans and H. verticillata, respectively. Both clone libraries included some sequences related to those of methanotrophs and nitrogen-fixing bacteria; (3) Cluster analysis of the T-RFLP profiles showed two distinct clusters corresponding to the two plant populations. Both ANOSIM of the T-RFLP data and Libshuff analysis of the two clone libraries indicated a significant difference in epiphytic bacterial communities between the two plants. Therefore, the epiphytic bacterial communities on submerged macrophytes appear to be diverse and host-specific, which may aid in understanding the ecological functions of submerged macrophytes in general.
文摘The results of design and experiment of a submerged semi-circular breakwater at the Yangtze estuary show that the submerged structure will be unsafe when the general empirical wave force formula for semi-circular breakwater is used in design. Therefore, a new calculation method for the wave forces acting on a submerged semi-circular structure is given in this paper, in which the wave force acting on the inside circumference of semi-circular arch is included, and the phase modification coefficient in the general empirical formula is adjusted as well. The new wave force calculation method has been Verified by the results of seven related physical model tests and adopted in the design of the south esturary jetty of the first stage project of Deep Channel Improvement Project of the Yangtze River Estuary, the total jetty length being 17.5 km.
