We investigate the effects of projectile material on high-speed penetration/perforation of Inconel 718 alloy(IN718)plates.High-speed ballistic impact tests are conducted on 2 mm-thickness IN718 plates with 5-mm-diamet...We investigate the effects of projectile material on high-speed penetration/perforation of Inconel 718 alloy(IN718)plates.High-speed ballistic impact tests are conducted on 2 mm-thickness IN718 plates with 5-mm-diameter stainless steel 304(SS304),Ti alloy TC4,and Al alloy AA1060 spherical projectiles.The impact processes are captured with high-speed photography.Optical and scanning electron microscopy and laser scan are conducted on recovered projectiles and targets.Finite element models of the ballistic impact are established based on the coupled Eulerian-Lagrangian algorithm with the Johnson-Cook constitutive model and failure criterion,and can well reproduce the experimental results.The experimental and simulated data related to projectile dynamics,and the geometries of postmortem projectiles and bullet holes are analyzed with phenomenological models.Projectile velocity evolution can be described with hydrodynamic models of penetration.Dimensional analysis reveals a universal relationship between the bullet hole expansion coefficient and the normalized dynamic pressure,regardless of the projectile material.However,the projectile material does affect projectile deformation,bullet hole size,and energy absorption of target.展开更多
Direct current（DC） and radio frequency（RF） performances of InP-based high electron mobility transistors（HEMTs）are investigated by Sentaurus TCAD. The physical models including hydrodynamic transport model, Shock...Direct current（DC） and radio frequency（RF） performances of InP-based high electron mobility transistors（HEMTs）are investigated by Sentaurus TCAD. The physical models including hydrodynamic transport model, Shockley–Read–Hall recombination, Auger recombination, radiative recombination, density gradient model and high field-dependent mobility are used to characterize the devices. The simulated results and measured results about DC and RF performances are compared, showing that they are well matched. However, the slight differences in channel current and pinch-off voltage may be accounted for by the surface defects resulting from oxidized InAlAs material in the gate-recess region. Moreover,the simulated frequency characteristics can be extrapolated beyond the test equipment limitation of 40 GHz, which gives a more accurate maximum oscillation frequency( f;) of 385 GHz.展开更多
One of the largest known megafloods on earth resulted from a glacier dam-break,which occurred during the Late Quaternary in the Altai Mountains in Southern Siberia.Computational modeling is one of the viable approache...One of the largest known megafloods on earth resulted from a glacier dam-break,which occurred during the Late Quaternary in the Altai Mountains in Southern Siberia.Computational modeling is one of the viable approaches to enhancing the understanding of the flood events.The computational domain of this flood is over 9460 km2 and about 3.784 × 106 cells are involved as a 50 m × 50 m mesh is used,which necessitates a computationally efficient model.Here the Open MP(Open Multiprocessing) technique is adopted to parallelize the code of a coupled 2D hydrodynamic and sediment transport model.It is shown that the computational efficiency is enhanced by over 80% due to the parallelization.The floods over both fixed and mobile beds are well reproduced with specified discharge hydrographs at the dam site.Qualitatively,backwater effects during the flood are resolved at the bifurcation between the Chuja and Katun rivers.Quantitatively,the computed maximum stage and thalweg are physically consistent with the field data of the bars and deposits.The effects of sediment transport and morphological evolution on the flood are considerable.Sensitivity analyses indicate that the impact of the peak discharge is significant,whilst those of the Manningroughness,medium sediment size and shape of the inlet discharge hydrograph are marginal.展开更多
To provide a suitable model for AUV simulation and control purposes, a general nonlinear dynamic model including a novel thruster hydrodynamics model was derived. Based on the modeling method, the "AUV-XX" s...To provide a suitable model for AUV simulation and control purposes, a general nonlinear dynamic model including a novel thruster hydrodynamics model was derived. Based on the modeling method, the "AUV-XX" simulation platform was established to carry out fundamental tests on its motion characteristics, stability, and controllability. A motion control strategy consisting of both position and speed control in a horizontal plane was designed for different task assignments of underwater vehicles. Combined control of heave and pitch was adopted to compensate for the reduction of vertical tunnel thrusters when the vehicle is moving at a high speed. An improved S-surface controller based on the capacitor plate model was developed with flexible gain selections made possible by different forms of restricting the error and changing the rate of the error. Simulation results show that the derived general mathematical model together with simulation platform can provide a test bed for fundamental tests of motion control. Additionally, the capacitor plate model S-surface control shows a good performance in guiding the vehicle to achieve the desired position and speed with sufficient accuracy.展开更多
Among the proposed techniques for delivering drugs to specific locations within human body, magnetic drug targeting prevails due to its non-invasive character and its high targeting efficiency. Magnetic targeting drug...Among the proposed techniques for delivering drugs to specific locations within human body, magnetic drug targeting prevails due to its non-invasive character and its high targeting efficiency. Magnetic targeting drug delivery is a method of carrying drug-loaded magnetic nanoparticles to a target tissue target under the applied magnetic field. This method increases the drug concentration in the target while reducing the adverse side-effects. Although there have been some theoretical analyses for magnetic drug targeting, very few researchers have addressed the hydrodynamic models of magnetic fluids in the blood vessel. A mathematical model is presented to describe the hydrodynamics of ferrofiuids as drug carriers flowing in a blood vessel under the applied magnetic field. In this model, magnetic force and asymmetrical force are added, and an angular momentum equation of magnetic nanoparticles in the applied magnetic field is modeled. Engineering approximations are achieved by retaining the physically most significant items in the model due to the mathematical complexity of the motion equations. Numerical simulations are performed to obtain better insight into the theoretical model with computational fluid dynamics. Simulation results demonstrate the important parameters leading to adequate drug delivery to the target site depending on the magnetic field intensity, which coincident with those of animal experiments. Results of the analysis provide important information and suggest strategies for improving delivery in clinical application.展开更多
A new two-dimensional lattice hydrodynamic model considering the turning capability of cars is proposed. Based on this model, the stability condition for this new model is obtained by using linear stability analysis. ...A new two-dimensional lattice hydrodynamic model considering the turning capability of cars is proposed. Based on this model, the stability condition for this new model is obtained by using linear stability analysis. Near the critical point, the modified KdV equation is deduced by using the nonlinear theory. The results of numerical simulation indicate that the critical point ac increases with the increase of the fraction p of northbound cars which continue to move along the positive y direction for c = 0.3, but decreases with the increase of p for c = 0.7. The results also indicate that the cars moving along only one direction （eastbound or northbound） are most stable.展开更多
The problem of flooding in Central Vietnam in general and the lower Ba River in particular is one of the natural disasters that frequently threatens people's lives and socioeconomic development in the region.Espec...The problem of flooding in Central Vietnam in general and the lower Ba River in particular is one of the natural disasters that frequently threatens people's lives and socioeconomic development in the region.Especially,climate change is becoming ever more prominent and hotter,making extreme natural disasters more unusual and unpredictable.In this research,MIKE-FLOOD—a model that connects a 1-dimensional(1-D)MIKE 11 Hydrodynamics(HD)model with a 2-dimensional(2-D)MIKE 21 HD model—was used to set up.The model was calculated for three floods:(1)flood in October 1993,(2)flood in November 2003,and(3)flood in November 2007;these are floods with high frequency and relatively large magnitude.The results show that the 1993 flood rose and receded quickly.The flood peak inundated an area of 22,600 ha,accounting for 52%of the natural area.The flooded areas deeper than 1,2,3,4,and 5m were 16500,11,000,7000,4200,and 2200 ha,respectively.In the center of Tuy Hoa city,the flooded area at the time of maximum water level was almost 100%.展开更多
Mangrove ecosystems along Vietnam’s coastline face significant degradation due to human activities,despite their crucial role in coastal protection against natural hazards.This study aims to assess the spatial and te...Mangrove ecosystems along Vietnam’s coastline face significant degradation due to human activities,despite their crucial role in coastal protection against natural hazards.This study aims to assess the spatial and temporal changes in mangrove coverage along Vietnam’s southern coast by integrating remote sensing techniques with hydrodynamic model simulations.The research methodology combines the Collect Earth tool analysis of Spot-4 and Planet satellite imagery(2000–2020)with Mike 21-HD two-dimensional(2D)hydrodynamic modeling to evaluate mangrove coverage changes by simulating shoreline erosion.Results analysis reveals that a significant increase of 109.83 ha in mangrove area within Vinh Chau Town of Soc Trang Province during the period 2010–2020,predominantly in the eastern region.Hydrodynamic simulations demonstrate that the coastal zone is primarily influenced by the interaction of nearshore currents,East Sea tides,and seasonal monsoon wave patterns.The model results effectively capture the complex interactions between these hydrodynamic factors and mangrove distribution.These findings not only validate the effectiveness of combining remote sensing and hydrodynamic modeling for mangrove assessment but also provide crucial insights for sustainable coastal ecosystem management.The study’s integrated approach offers a robust framework for monitoring mangrove dynamics and developing evidence-based conservation strategies,highlighting the importance of maintaining these vital ecosystems for coastal protection.展开更多
Vessel motions in offshore operations are heavily influenced by uncertain wave loads and hydrodynamic parameters.Yet,traditional deterministic or probabilistic models often fail to capture epistemic ambiguity when dat...Vessel motions in offshore operations are heavily influenced by uncertain wave loads and hydrodynamic parameters.Yet,traditional deterministic or probabilistic models often fail to capture epistemic ambiguity when data are scarce.We introduce a fuzzy–set framework usingα-cut interval analysis to represent imprecise wave heights,periods,added mass,damping,and stiffness as fuzzy numbers.These are incorporated into the multi-body equations of motion and solved via a fuzzy Runge–Kutta scheme across nestedα-levels.A simulation architecture iterates overα-cuts and time-steps to produce interval bounds on heavy responses.A case study off the Karnataka coast,with realistic sea-state data for moderate and severe scenarios,yields heave-amplitude envelopes whose widths quantify response uncertainty.At mid-confidence(α=0.5),moderate seas produce amplitudes of 8.30–9.65 m(±15%),while severe seas yield 7.15–8.90 m(±22%).Envelope narrowing asα→1 confirms that increased parameter confidence reduces prediction spread,and bias analysis against crisp baselines highlights the impact of imprecision on mean responses.This non-probabilistic approach provides interpretable,worst-and best-case motion bounds without requiring large datasets,offering marine engineers robust safety margins and guidance for targeted data collection and real-time uncertainty updating.展开更多
Offshore support operations must balance safety and sustainability under highly variable sea conditions.Deterministic motion analyses can underestimate extreme vessel responses,leading to insufficient operational limi...Offshore support operations must balance safety and sustainability under highly variable sea conditions.Deterministic motion analyses can underestimate extreme vessel responses,leading to insufficient operational limits and increased environmental impact.We develop a fuzzy‐enhanced multi‐body dynamics framework in which key inputs significant wave height,peak period,added mass,and radiation damping are represented as fuzzy numbers.Anα-cut decomposition yields interval bounds at each confidence level,and a fourth-order Runge-Kutta scheme integrates the six-degree-of-freedom equations of motion for both lower and upper“vertex”systems.A case study off the Karnataka coast applies both full 6-DoF and single-DOF heave approximations to demonstrate methodology.The heave response envelopes under calm(nominalα=1:0.73 m;full range atα=0:0.64–1.64 m)and severe(nominal 1.58 m;range 1.32–2.36 m)sea states reveal potential underestimations of 124%and 49%,respectively,when using only nominal values.By selecting an operationalα-level(e.g.,α^(*)=0.35 to cap heave≤1.8 m),decision-makers can balance risk tolerance and conservatism.Sensitivity analysis identifies significant wave height as the dominant uncertainty driver.Computational trade-offs and adaptiveα-sampling strategies are discussed.This work provides a self-contained,uncertainty-aware tool for deriving operational envelopes that improve risk-informed planning and enable fuel-efficiency optimization.By embedding fuzzy uncertainty quantification into vessel dynamics,the methodology supports safer,more sustainable marine operations and can be extended to real-time sensor fusion,multi-vessel interactions,and frequency-dependent hydrodynamics.展开更多
A floating nuclear power plant(FNPP)is an offshore facility that integrates proven light-water reactor technologies with floating platform characteristics.However,frequent contact with marine environments may lead to ...A floating nuclear power plant(FNPP)is an offshore facility that integrates proven light-water reactor technologies with floating platform characteristics.However,frequent contact with marine environments may lead to wave-induced vibrations and oscillations.This study aimed to evaluate the wave danger on FNPPs,which can negatively impact FNPP functionality.We developed a hydrodynamic model of an FNPP using potential flow theory and computed the frequency-domain fluid dynamic responses.After verifying the hydrodynamic model,we developed a predictive model for FNPP responses.This model utilizes a genetic aggregation methodology for batch prediction while ensuring accuracy.We analyzed all the wave data from a selected sea area over the past 50 years using the constructed surrogate model,enabling us to identify dangerous marine areas.By utilizing the extreme value distribution of important wave heights in these areas,we determined the wave return period,which poses a threat to FNPPs.This provides an important method for analyzing wave hazards to FNPPs.展开更多
While the abundances of the final state hadrons in relativistic heavy-ion collisions are rather well described by the thermal particle production,the shape of the transverse momentum,pT,distribution below p_(T)≈500 M...While the abundances of the final state hadrons in relativistic heavy-ion collisions are rather well described by the thermal particle production,the shape of the transverse momentum,pT,distribution below p_(T)≈500 MeV/c,is still poorly understood.We propose a procedure to quantify the model-to-data differences using Bayesian inference techniques,which allows for consistent treatment of the experimental uncertainties and tests the completeness of the available hydrodynamic frameworks.Using relativistic fluid framework FluiduM with PCE coupled to TrENTo initial state and FasTrEso decays,we analyze p_(T)distribution of identified charged hadrons measured in heavy-ion collisions at top RHIC and the LHC energies and identify an excess of pions produced below p_(T)≈500 MeV/c.Our results provide new input for the interpretation of the pion excess as either missing components in the thermal particle yield description or as an evidence for a different particle production mechanism.展开更多
The structural design of wave energy harvesting devices play a crucial role in complex marine environments.To enhance output performance of triboelectric nanogenerator(TENG)in small-amplitude wave environments,this pa...The structural design of wave energy harvesting devices play a crucial role in complex marine environments.To enhance output performance of triboelectric nanogenerator(TENG)in small-amplitude wave environments,this paper proposes a floating design method that utilizes wave energy converter(WEC)combined with elastic support coupled TENG based on boat design concepts.Using hydrodynamic model,the study investigates various types of WEC structures,resulting in maximum energy generation for the TENG.Additionally,the coupled TENG designed with elastic support demonstrates excellent performance in various experiments.The results indicate that the power density of the coupled TENG can reach 13 W/m^(3).Wave testing confirms that various floating structures significant differences in TENG output performance,and the boat-type float notably enhances the performance of TENG.The boat-type TENG exhibits an increase of 155%in open-circuit voltage,414%in short-circuit current,and 218%in transferred charge for the interpolated electrodes,compared to the lowest square-type TENG.This work presents a novel approach for WEC design and improving energy conversion efficiency in large-scale ocean wave energy collection and accelerates the industrialization process of TENG in the field of marine engineering.展开更多
In order to simulate changes in the water quality of the Miyun Reservoir dueto continuous descent of surface water level, a 3-D ecological hydrodynamic model was developedthrough coupling the water quality analysis si...In order to simulate changes in the water quality of the Miyun Reservoir dueto continuous descent of surface water level, a 3-D ecological hydrodynamic model was developedthrough coupling the water quality analysis simulation program (WASP) with the environmental fluiddynamics code (EFDC). The model was then calibrated and verified. Four scenarios (S1, S21, S22 andS23) were simulated using the model. Results show that the water quality of the Miyun Reservoirunder conditions of low surface water level is apparently affected by different amounts of inflowand different total phosphorus (TP) loadings. The chlorophyll-a concentration might exceed 10 μg/Lin many areas of the Miyun Reservoir (This limitative value is seen as a critical value ofeutrophication) when large loadings of TP enter due to the amount of inflow increasing. Results ofscenario S23 indicate that control of TP loadings can decrease chlorophyll-a concentrationeffectively, and the water quality of the Miyun Reservoir will improve or retain its status quo.展开更多
In order to optimize the design of a 12.5 m deepwater channel project and protect the ecological environment, it is necessary to study the habitat evaluation of species in the engineered area. A coupled eco-hydrodynam...In order to optimize the design of a 12.5 m deepwater channel project and protect the ecological environment, it is necessary to study the habitat evaluation of species in the engineered area. A coupled eco-hydrodynamic model, which combines a hydrodynamic model （ADCIRC） and a habitat suitability index （HSI） model is developed for target fish （Coilia nasus） and benthos （Corbicula fluminea） in the Yangtze River in order to predict the ecological changes and optimize the regulation scheme. Based on the existing research concerning the characteristics of Coilia nasus and Corbicula fluminea, the relationship between the target species and water environment factors is established. The verification results of tidal level, velocity and biological density show that the proposed coupling model performs well when predicting ecological suitability in the studied region. The results indicate a slight improvement in the potential habitat availability for the two species studied as the natural hydraulic conditions change after the deep-water channel regulation works.展开更多
In sub-tropical coastal waters around Hong Kong, algal blooms and red tides are usually first sighted in the Mirs Bay, in the eastern waters of Hong Kong. A calibrated three-dimensional hydrodynamic model for the Pear...In sub-tropical coastal waters around Hong Kong, algal blooms and red tides are usually first sighted in the Mirs Bay, in the eastern waters of Hong Kong. A calibrated three-dimensional hydrodynamic model for the Pearl River Estuary （Delft3D） has been applied to the study of the physical hydrography of Hong Kong waters and its relationship with algal bloom transport patterns in the dry and wet seasons. The general 3D hydrodynamic circulation and salinity structure in the partially-mixed estuary are presented. Extensive numerical surface drogue tracking experiments are performed for algal blooms that are initiated in the Mirs Bay under different seasonal, wind and tidal conditions. The probability of bloom impact on the Victoria Harbour and nearby urban coastal waters is estimated. The computations show that： i） In the wet season （May - August）, algal blooms initiated in the Mirs Bay will move in a clockwise direction out of the bay, and be transported away from Hong Kong due to SW monsoon winds which drive the SW to NE coastal current; ii） In the dry season （November- April）, algal blooms initiated in the northeast Mirs Bay will move in an anti-clockwise direction and be carried away into southern waters due to the NE to SW coastal current driven by the NE monsoon winds; the bloom typically flows past the east edge of the Victoria Harbeur and nearby waters. Finally, the role of hydrodynamic transport in an important episodic event -- the spring 1998 massive red tide -- is quantitatively examined. It is shown that the strong NE to E wind during late March to early April, coupled with the diurnal tide at the beginning of April, significantly increased the probability of bloom transport into the Port Shelter and East Lamma Channel, resulting in the massive fish kill. The results provide a basis for risk assessment of harmful algal bloom （HAB） impact on urban coastal waters around the Victoria Habour.展开更多
The hydrodynamic effects of reconnecting a lake group with the Yangtze River were simulated using a three-dimensional hydrodynamic model. The model was calibrated and validated using the measured water temperature and...The hydrodynamic effects of reconnecting a lake group with the Yangtze River were simulated using a three-dimensional hydrodynamic model. The model was calibrated and validated using the measured water temperature and total phosphorous. The circulation patterns, water temperature, and water exchange conditions between sub-lakes were simulated under two conditions： （1） the present condition, in which the lake group is isolated from the Yangtze River; and （2） the future condition, with a proposed improvement in which connecting the lake group with the Yangtze River will allow river water to be diverted into the lake group. The simulation period selected was characterized by extremely high temperature and very little rain. The results show that the cold inflow from the river has a significant effect on the water temperature only near the inlets, and the effect is more obvious in the lower water layers than that in the upper ones. The circulation pattern changes significantly and small-scale vortices only exist in part of the lake regions. The water exchange between sub-lakes is greatly enhanced with the proposed improvement. The water replacement rate increases with water diversion but varies in different sub-lakes. Finally, a new water diversion scheme was proposed to avoid contamination of some lakes in the early stage.展开更多
By use of the hydrodynamic model, the harmonic constants of 8 principal tidal constituents (Q(1), O-1, P-1, K-1, N-2, M-2, S-2 and K-2) are obtained for the East China Sea, and the harmonic constant of S-a is calculat...By use of the hydrodynamic model, the harmonic constants of 8 principal tidal constituents (Q(1), O-1, P-1, K-1, N-2, M-2, S-2 and K-2) are obtained for the East China Sea, and the harmonic constant of S-a is calculated by two-dimensional interpolation. The calculated results agree well with the observed data around the sea. The harmonic constants can be used to predict the tide in the East China Sea. The cotidal charts of the 9 tidal constituents reveal their distribution.展开更多
With the development of industry and agriculture,nitrogen,phosphorus and other nutrients in the Hanshui River greatly increase and eutrophication has become an important threat to the water quality of the Hanshui Rive...With the development of industry and agriculture,nitrogen,phosphorus and other nutrients in the Hanshui River greatly increase and eutrophication has become an important threat to the water quality of the Hanshui River,especially in the middle and lower reaches.The primary objective of this study was to establish the water quality model for the middle and lower reaches of the Hanshui River based on the model of MIKE 11.The main pollutants migration and transformation process could be simulated using the water quality model.The rainfall-runoff model,hy-drodynamic model and water quality model were established using MIKE 11.The pollutants,such as chemical oxygen demand(COD),biochemical oxygen demand(BOD),ammonia nitrogen,nitrate nitrogen,phosphorus,dissolved oxy-gen(DO),were simulated and predicted using the above three models.A set of methods computing non-point source pollution load of the Hanshui River Basin was proposed in this study.The simulated and observed values of COD,BOD5,ammonia,nitrate,DO,and total phosphorus were compared after the parameter calibration of the water quality model.The simulated and observed results match better,thus the model can be used to predict water quality in the fu-ture for the Hanshui River.The pollution trend could be predicted using the water quality model according pollution load generation.It is helpful for government to take effective measures to prevent the water bloom and protect water quality in the river.展开更多
基金supported by National Natural Science Foundation of China(No.12402465)Sichuan Science and Technology Program(No.2023NSFSC1284)。
文摘We investigate the effects of projectile material on high-speed penetration/perforation of Inconel 718 alloy(IN718)plates.High-speed ballistic impact tests are conducted on 2 mm-thickness IN718 plates with 5-mm-diameter stainless steel 304(SS304),Ti alloy TC4,and Al alloy AA1060 spherical projectiles.The impact processes are captured with high-speed photography.Optical and scanning electron microscopy and laser scan are conducted on recovered projectiles and targets.Finite element models of the ballistic impact are established based on the coupled Eulerian-Lagrangian algorithm with the Johnson-Cook constitutive model and failure criterion,and can well reproduce the experimental results.The experimental and simulated data related to projectile dynamics,and the geometries of postmortem projectiles and bullet holes are analyzed with phenomenological models.Projectile velocity evolution can be described with hydrodynamic models of penetration.Dimensional analysis reveals a universal relationship between the bullet hole expansion coefficient and the normalized dynamic pressure,regardless of the projectile material.However,the projectile material does affect projectile deformation,bullet hole size,and energy absorption of target.
基金supported by the National Natural Science Foundation of China(Grant Nos.61404115 and 61434006)the Postdoctoral Science Foundation of Henan Province,China(Grant No.2014006)the Development Fund for Outstanding Young Teachers of Zhengzhou University(Grant No.1521317004)
文摘Direct current（DC） and radio frequency（RF） performances of InP-based high electron mobility transistors（HEMTs）are investigated by Sentaurus TCAD. The physical models including hydrodynamic transport model, Shockley–Read–Hall recombination, Auger recombination, radiative recombination, density gradient model and high field-dependent mobility are used to characterize the devices. The simulated results and measured results about DC and RF performances are compared, showing that they are well matched. However, the slight differences in channel current and pinch-off voltage may be accounted for by the surface defects resulting from oxidized InAlAs material in the gate-recess region. Moreover,the simulated frequency characteristics can be extrapolated beyond the test equipment limitation of 40 GHz, which gives a more accurate maximum oscillation frequency( f;) of 385 GHz.
基金funded by Natural Science Foundation of China (Grants No. 11172217 and 11432015)National Key Basic Research and Development Program (i.e., 973 Program) of China (Grant No. 2007CB714106)
文摘One of the largest known megafloods on earth resulted from a glacier dam-break,which occurred during the Late Quaternary in the Altai Mountains in Southern Siberia.Computational modeling is one of the viable approaches to enhancing the understanding of the flood events.The computational domain of this flood is over 9460 km2 and about 3.784 × 106 cells are involved as a 50 m × 50 m mesh is used,which necessitates a computationally efficient model.Here the Open MP(Open Multiprocessing) technique is adopted to parallelize the code of a coupled 2D hydrodynamic and sediment transport model.It is shown that the computational efficiency is enhanced by over 80% due to the parallelization.The floods over both fixed and mobile beds are well reproduced with specified discharge hydrographs at the dam site.Qualitatively,backwater effects during the flood are resolved at the bifurcation between the Chuja and Katun rivers.Quantitatively,the computed maximum stage and thalweg are physically consistent with the field data of the bars and deposits.The effects of sediment transport and morphological evolution on the flood are considerable.Sensitivity analyses indicate that the impact of the peak discharge is significant,whilst those of the Manningroughness,medium sediment size and shape of the inlet discharge hydrograph are marginal.
基金the National Science Foundation under Grant No.50879014,No.50909025
文摘To provide a suitable model for AUV simulation and control purposes, a general nonlinear dynamic model including a novel thruster hydrodynamics model was derived. Based on the modeling method, the "AUV-XX" simulation platform was established to carry out fundamental tests on its motion characteristics, stability, and controllability. A motion control strategy consisting of both position and speed control in a horizontal plane was designed for different task assignments of underwater vehicles. Combined control of heave and pitch was adopted to compensate for the reduction of vertical tunnel thrusters when the vehicle is moving at a high speed. An improved S-surface controller based on the capacitor plate model was developed with flexible gain selections made possible by different forms of restricting the error and changing the rate of the error. Simulation results show that the derived general mathematical model together with simulation platform can provide a test bed for fundamental tests of motion control. Additionally, the capacitor plate model S-surface control shows a good performance in guiding the vehicle to achieve the desired position and speed with sufficient accuracy.
基金the National Basic Research Program of China(973 Program)(No.2007CB936004)the National Natural Science Foundation of China(No.50875169)
文摘Among the proposed techniques for delivering drugs to specific locations within human body, magnetic drug targeting prevails due to its non-invasive character and its high targeting efficiency. Magnetic targeting drug delivery is a method of carrying drug-loaded magnetic nanoparticles to a target tissue target under the applied magnetic field. This method increases the drug concentration in the target while reducing the adverse side-effects. Although there have been some theoretical analyses for magnetic drug targeting, very few researchers have addressed the hydrodynamic models of magnetic fluids in the blood vessel. A mathematical model is presented to describe the hydrodynamics of ferrofiuids as drug carriers flowing in a blood vessel under the applied magnetic field. In this model, magnetic force and asymmetrical force are added, and an angular momentum equation of magnetic nanoparticles in the applied magnetic field is modeled. Engineering approximations are achieved by retaining the physically most significant items in the model due to the mathematical complexity of the motion equations. Numerical simulations are performed to obtain better insight into the theoretical model with computational fluid dynamics. Simulation results demonstrate the important parameters leading to adequate drug delivery to the target site depending on the magnetic field intensity, which coincident with those of animal experiments. Results of the analysis provide important information and suggest strategies for improving delivery in clinical application.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10865001, 11047003, 11172164, and 11162019)the Youth Foundation of the Yulin Normal University of China (Grant No. 2011YJQN01)
文摘A new two-dimensional lattice hydrodynamic model considering the turning capability of cars is proposed. Based on this model, the stability condition for this new model is obtained by using linear stability analysis. Near the critical point, the modified KdV equation is deduced by using the nonlinear theory. The results of numerical simulation indicate that the critical point ac increases with the increase of the fraction p of northbound cars which continue to move along the positive y direction for c = 0.3, but decreases with the increase of p for c = 0.7. The results also indicate that the cars moving along only one direction （eastbound or northbound） are most stable.
基金Asia-Pacific Network for Global Change Research,Grant/Award Number:CRRP2020-09MYKantoush。
文摘The problem of flooding in Central Vietnam in general and the lower Ba River in particular is one of the natural disasters that frequently threatens people's lives and socioeconomic development in the region.Especially,climate change is becoming ever more prominent and hotter,making extreme natural disasters more unusual and unpredictable.In this research,MIKE-FLOOD—a model that connects a 1-dimensional(1-D)MIKE 11 Hydrodynamics(HD)model with a 2-dimensional(2-D)MIKE 21 HD model—was used to set up.The model was calculated for three floods:(1)flood in October 1993,(2)flood in November 2003,and(3)flood in November 2007;these are floods with high frequency and relatively large magnitude.The results show that the 1993 flood rose and receded quickly.The flood peak inundated an area of 22,600 ha,accounting for 52%of the natural area.The flooded areas deeper than 1,2,3,4,and 5m were 16500,11,000,7000,4200,and 2200 ha,respectively.In the center of Tuy Hoa city,the flooded area at the time of maximum water level was almost 100%.
基金supported by Environmental Protection Project 2023-2024,with the Joint Vietnam-Russia Tropical Science and Technology Research Center(Southern Branch)as the lead Institution.
文摘Mangrove ecosystems along Vietnam’s coastline face significant degradation due to human activities,despite their crucial role in coastal protection against natural hazards.This study aims to assess the spatial and temporal changes in mangrove coverage along Vietnam’s southern coast by integrating remote sensing techniques with hydrodynamic model simulations.The research methodology combines the Collect Earth tool analysis of Spot-4 and Planet satellite imagery(2000–2020)with Mike 21-HD two-dimensional(2D)hydrodynamic modeling to evaluate mangrove coverage changes by simulating shoreline erosion.Results analysis reveals that a significant increase of 109.83 ha in mangrove area within Vinh Chau Town of Soc Trang Province during the period 2010–2020,predominantly in the eastern region.Hydrodynamic simulations demonstrate that the coastal zone is primarily influenced by the interaction of nearshore currents,East Sea tides,and seasonal monsoon wave patterns.The model results effectively capture the complex interactions between these hydrodynamic factors and mangrove distribution.These findings not only validate the effectiveness of combining remote sensing and hydrodynamic modeling for mangrove assessment but also provide crucial insights for sustainable coastal ecosystem management.The study’s integrated approach offers a robust framework for monitoring mangrove dynamics and developing evidence-based conservation strategies,highlighting the importance of maintaining these vital ecosystems for coastal protection.
文摘Vessel motions in offshore operations are heavily influenced by uncertain wave loads and hydrodynamic parameters.Yet,traditional deterministic or probabilistic models often fail to capture epistemic ambiguity when data are scarce.We introduce a fuzzy–set framework usingα-cut interval analysis to represent imprecise wave heights,periods,added mass,damping,and stiffness as fuzzy numbers.These are incorporated into the multi-body equations of motion and solved via a fuzzy Runge–Kutta scheme across nestedα-levels.A simulation architecture iterates overα-cuts and time-steps to produce interval bounds on heavy responses.A case study off the Karnataka coast,with realistic sea-state data for moderate and severe scenarios,yields heave-amplitude envelopes whose widths quantify response uncertainty.At mid-confidence(α=0.5),moderate seas produce amplitudes of 8.30–9.65 m(±15%),while severe seas yield 7.15–8.90 m(±22%).Envelope narrowing asα→1 confirms that increased parameter confidence reduces prediction spread,and bias analysis against crisp baselines highlights the impact of imprecision on mean responses.This non-probabilistic approach provides interpretable,worst-and best-case motion bounds without requiring large datasets,offering marine engineers robust safety margins and guidance for targeted data collection and real-time uncertainty updating.
文摘Offshore support operations must balance safety and sustainability under highly variable sea conditions.Deterministic motion analyses can underestimate extreme vessel responses,leading to insufficient operational limits and increased environmental impact.We develop a fuzzy‐enhanced multi‐body dynamics framework in which key inputs significant wave height,peak period,added mass,and radiation damping are represented as fuzzy numbers.Anα-cut decomposition yields interval bounds at each confidence level,and a fourth-order Runge-Kutta scheme integrates the six-degree-of-freedom equations of motion for both lower and upper“vertex”systems.A case study off the Karnataka coast applies both full 6-DoF and single-DOF heave approximations to demonstrate methodology.The heave response envelopes under calm(nominalα=1:0.73 m;full range atα=0:0.64–1.64 m)and severe(nominal 1.58 m;range 1.32–2.36 m)sea states reveal potential underestimations of 124%and 49%,respectively,when using only nominal values.By selecting an operationalα-level(e.g.,α^(*)=0.35 to cap heave≤1.8 m),decision-makers can balance risk tolerance and conservatism.Sensitivity analysis identifies significant wave height as the dominant uncertainty driver.Computational trade-offs and adaptiveα-sampling strategies are discussed.This work provides a self-contained,uncertainty-aware tool for deriving operational envelopes that improve risk-informed planning and enable fuel-efficiency optimization.By embedding fuzzy uncertainty quantification into vessel dynamics,the methodology supports safer,more sustainable marine operations and can be extended to real-time sensor fusion,multi-vessel interactions,and frequency-dependent hydrodynamics.
文摘A floating nuclear power plant(FNPP)is an offshore facility that integrates proven light-water reactor technologies with floating platform characteristics.However,frequent contact with marine environments may lead to wave-induced vibrations and oscillations.This study aimed to evaluate the wave danger on FNPPs,which can negatively impact FNPP functionality.We developed a hydrodynamic model of an FNPP using potential flow theory and computed the frequency-domain fluid dynamic responses.After verifying the hydrodynamic model,we developed a predictive model for FNPP responses.This model utilizes a genetic aggregation methodology for batch prediction while ensuring accuracy.We analyzed all the wave data from a selected sea area over the past 50 years using the constructed surrogate model,enabling us to identify dangerous marine areas.By utilizing the extreme value distribution of important wave heights in these areas,we determined the wave return period,which poses a threat to FNPPs.This provides an important method for analyzing wave hazards to FNPPs.
文摘While the abundances of the final state hadrons in relativistic heavy-ion collisions are rather well described by the thermal particle production,the shape of the transverse momentum,pT,distribution below p_(T)≈500 MeV/c,is still poorly understood.We propose a procedure to quantify the model-to-data differences using Bayesian inference techniques,which allows for consistent treatment of the experimental uncertainties and tests the completeness of the available hydrodynamic frameworks.Using relativistic fluid framework FluiduM with PCE coupled to TrENTo initial state and FasTrEso decays,we analyze p_(T)distribution of identified charged hadrons measured in heavy-ion collisions at top RHIC and the LHC energies and identify an excess of pions produced below p_(T)≈500 MeV/c.Our results provide new input for the interpretation of the pion excess as either missing components in the thermal particle yield description or as an evidence for a different particle production mechanism.
基金supported by the China Postdoctoral Science Fund(No.2023M734086).
文摘The structural design of wave energy harvesting devices play a crucial role in complex marine environments.To enhance output performance of triboelectric nanogenerator(TENG)in small-amplitude wave environments,this paper proposes a floating design method that utilizes wave energy converter(WEC)combined with elastic support coupled TENG based on boat design concepts.Using hydrodynamic model,the study investigates various types of WEC structures,resulting in maximum energy generation for the TENG.Additionally,the coupled TENG designed with elastic support demonstrates excellent performance in various experiments.The results indicate that the power density of the coupled TENG can reach 13 W/m^(3).Wave testing confirms that various floating structures significant differences in TENG output performance,and the boat-type float notably enhances the performance of TENG.The boat-type TENG exhibits an increase of 155%in open-circuit voltage,414%in short-circuit current,and 218%in transferred charge for the interpolated electrodes,compared to the lowest square-type TENG.This work presents a novel approach for WEC design and improving energy conversion efficiency in large-scale ocean wave energy collection and accelerates the industrialization process of TENG in the field of marine engineering.
文摘In order to simulate changes in the water quality of the Miyun Reservoir dueto continuous descent of surface water level, a 3-D ecological hydrodynamic model was developedthrough coupling the water quality analysis simulation program (WASP) with the environmental fluiddynamics code (EFDC). The model was then calibrated and verified. Four scenarios (S1, S21, S22 andS23) were simulated using the model. Results show that the water quality of the Miyun Reservoirunder conditions of low surface water level is apparently affected by different amounts of inflowand different total phosphorus (TP) loadings. The chlorophyll-a concentration might exceed 10 μg/Lin many areas of the Miyun Reservoir (This limitative value is seen as a critical value ofeutrophication) when large loadings of TP enter due to the amount of inflow increasing. Results ofscenario S23 indicate that control of TP loadings can decrease chlorophyll-a concentrationeffectively, and the water quality of the Miyun Reservoir will improve or retain its status quo.
基金The National Natural Science Foundation of China(No.51209040,51279134)the Natural Science Foundation of Jiangsu Province(No.BK2012341)
文摘In order to optimize the design of a 12.5 m deepwater channel project and protect the ecological environment, it is necessary to study the habitat evaluation of species in the engineered area. A coupled eco-hydrodynamic model, which combines a hydrodynamic model （ADCIRC） and a habitat suitability index （HSI） model is developed for target fish （Coilia nasus） and benthos （Corbicula fluminea） in the Yangtze River in order to predict the ecological changes and optimize the regulation scheme. Based on the existing research concerning the characteristics of Coilia nasus and Corbicula fluminea, the relationship between the target species and water environment factors is established. The verification results of tidal level, velocity and biological density show that the proposed coupling model performs well when predicting ecological suitability in the studied region. The results indicate a slight improvement in the potential habitat availability for the two species studied as the natural hydraulic conditions change after the deep-water channel regulation works.
基金This study was supported by a Hong Kong Research Grants Council Group Research Project (RGC//HKU1/02C) ,and partially by a grantfromthe University Grants Committee of the Hong Kong Special Administrative Region,China(Project No. AoE/P-04/04 and P-04/02) tothe Area of Excellencein Marine Environment Research andInnovativeTechnology (MERIT)
文摘In sub-tropical coastal waters around Hong Kong, algal blooms and red tides are usually first sighted in the Mirs Bay, in the eastern waters of Hong Kong. A calibrated three-dimensional hydrodynamic model for the Pearl River Estuary （Delft3D） has been applied to the study of the physical hydrography of Hong Kong waters and its relationship with algal bloom transport patterns in the dry and wet seasons. The general 3D hydrodynamic circulation and salinity structure in the partially-mixed estuary are presented. Extensive numerical surface drogue tracking experiments are performed for algal blooms that are initiated in the Mirs Bay under different seasonal, wind and tidal conditions. The probability of bloom impact on the Victoria Harbour and nearby urban coastal waters is estimated. The computations show that： i） In the wet season （May - August）, algal blooms initiated in the Mirs Bay will move in a clockwise direction out of the bay, and be transported away from Hong Kong due to SW monsoon winds which drive the SW to NE coastal current; ii） In the dry season （November- April）, algal blooms initiated in the northeast Mirs Bay will move in an anti-clockwise direction and be carried away into southern waters due to the NE to SW coastal current driven by the NE monsoon winds; the bloom typically flows past the east edge of the Victoria Harbeur and nearby waters. Finally, the role of hydrodynamic transport in an important episodic event -- the spring 1998 massive red tide -- is quantitatively examined. It is shown that the strong NE to E wind during late March to early April, coupled with the diurnal tide at the beginning of April, significantly increased the probability of bloom transport into the Port Shelter and East Lamma Channel, resulting in the massive fish kill. The results provide a basis for risk assessment of harmful algal bloom （HAB） impact on urban coastal waters around the Victoria Habour.
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education(Grant No. 20110142110064)Huazhong University of Science and Technology Indigenous Innovation Foundation(Grant No. 2010ZZ004-06)
文摘The hydrodynamic effects of reconnecting a lake group with the Yangtze River were simulated using a three-dimensional hydrodynamic model. The model was calibrated and validated using the measured water temperature and total phosphorous. The circulation patterns, water temperature, and water exchange conditions between sub-lakes were simulated under two conditions： （1） the present condition, in which the lake group is isolated from the Yangtze River; and （2） the future condition, with a proposed improvement in which connecting the lake group with the Yangtze River will allow river water to be diverted into the lake group. The simulation period selected was characterized by extremely high temperature and very little rain. The results show that the cold inflow from the river has a significant effect on the water temperature only near the inlets, and the effect is more obvious in the lower water layers than that in the upper ones. The circulation pattern changes significantly and small-scale vortices only exist in part of the lake regions. The water exchange between sub-lakes is greatly enhanced with the proposed improvement. The water replacement rate increases with water diversion but varies in different sub-lakes. Finally, a new water diversion scheme was proposed to avoid contamination of some lakes in the early stage.
文摘By use of the hydrodynamic model, the harmonic constants of 8 principal tidal constituents (Q(1), O-1, P-1, K-1, N-2, M-2, S-2 and K-2) are obtained for the East China Sea, and the harmonic constant of S-a is calculated by two-dimensional interpolation. The calculated results agree well with the observed data around the sea. The harmonic constants can be used to predict the tide in the East China Sea. The cotidal charts of the 9 tidal constituents reveal their distribution.
基金Under the auspices of National Science and Technology Research during the 11th Five-Year Plan Period (No.2008BAI62B05)National Natural Science Foundation of China (No. 50879005,51179006)
文摘With the development of industry and agriculture,nitrogen,phosphorus and other nutrients in the Hanshui River greatly increase and eutrophication has become an important threat to the water quality of the Hanshui River,especially in the middle and lower reaches.The primary objective of this study was to establish the water quality model for the middle and lower reaches of the Hanshui River based on the model of MIKE 11.The main pollutants migration and transformation process could be simulated using the water quality model.The rainfall-runoff model,hy-drodynamic model and water quality model were established using MIKE 11.The pollutants,such as chemical oxygen demand(COD),biochemical oxygen demand(BOD),ammonia nitrogen,nitrate nitrogen,phosphorus,dissolved oxy-gen(DO),were simulated and predicted using the above three models.A set of methods computing non-point source pollution load of the Hanshui River Basin was proposed in this study.The simulated and observed values of COD,BOD5,ammonia,nitrate,DO,and total phosphorus were compared after the parameter calibration of the water quality model.The simulated and observed results match better,thus the model can be used to predict water quality in the fu-ture for the Hanshui River.The pollution trend could be predicted using the water quality model according pollution load generation.It is helpful for government to take effective measures to prevent the water bloom and protect water quality in the river.
