In the actual monitoring of deep hole displacement,the identification of slip surfaces is primarily based on abrupt changes observed in the inclinometric curve.In conventional identification methods,inclinometric curv...In the actual monitoring of deep hole displacement,the identification of slip surfaces is primarily based on abrupt changes observed in the inclinometric curve.In conventional identification methods,inclinometric curves exhibiting indications of sliding can be categorized into three types:B-type,D-type,and r-type.The position of the slip surface is typically determined by identifying the depth corresponding to the point of maximum displacement mutation.However,this method is sensitive to the interval of measurement points and the observation scale of the coordinate axes and suffers from unclear sliding surfaces and uncertain values.Based on the variation characteristics of these diagonal curves,we classified the landslide into three components:the sliding body,the sliding interval,and the immobile body.Moreover,three different generalization models were established to analyze the relationships between the curve form and the slip surface location based on different physical indicators such as displacement rate,relative displacement,and acceleration.The results show that the displacement rate curves of an r-type slope exhibit a clustering feature in the sliding interval,and by solving for the depth of discrete points within the step phase,it is possible to determine the location of the slip surface.On the other hand,D-type slopes have inflection points in the relative displacement curve located at the slip surface.The acceleration curves of B-type slopes exhibit clustering characteristics during the sliding interval,while the scattered acceleration data demonstrate wandering characteristics.Consequently,the slip surface location can be revealed by solving the depth corresponding to the maximum acceleration with cubic spline interpolation.The approach proposed in this paper was applied to the monitoring data of a landslide in Yunnan Province,China.The results indicate that our approach can accurately identify the slip surface location and enable computability of its position,thereby enhancing applicability and reliability of the deep-hole displacement monitoring data.展开更多
Shear-thinning fluids have been widely used in microfluidic systems,but their internal flow mechanism is still unclear.Therefore,in this paper,molecular dynamics simulations are used to study the laminar flow of shear...Shear-thinning fluids have been widely used in microfluidic systems,but their internal flow mechanism is still unclear.Therefore,in this paper,molecular dynamics simulations are used to study the laminar flow of shear-thinning fluid in a microchannel.We validated the feasibility of our simulation method by evaluating the mean square displacement and Reynolds number of the solution layers.The results show that the change rule of the fluid system's velocity profile and interaction energy can reflect the shear-thinning characteristics of the fluids.The velocity profile resembles a top-hat shape,intensifying as the fluid's power law index decreases.The interaction energy between the wall and the fluid decreases gradually with increasing velocity,and a high concentration of non-Newtonian fluid reaches a plateau sooner.Moreover,the velocity profile of the fluid is related to the molecule number density distribution and their values are inversely proportional.By analyzing the radial distribution function,we found that the hydrogen bonds between solute and water molecules weaken with the increase in velocity.This observation offers an explanation for the shear-thinning phenomenon of the non-Newtonian flow from a micro perspective.展开更多
Wave climate analysis and other applications for the Pacific Ocean require a reliable wave hindcast. Five source and sink term packages in the Wavewatch III model(v3.14 and v4.18) are compared and assessed in this stu...Wave climate analysis and other applications for the Pacific Ocean require a reliable wave hindcast. Five source and sink term packages in the Wavewatch III model(v3.14 and v4.18) are compared and assessed in this study through comprehensive observations, including altimeter significant wave height, advanced synthetic aperture radar swell, and buoy wave parameters and spectrum. In addition to the evaluation of typically used integral parameters, the spectra partitioning method contributes to the detailed wave system and wave maturity validation. The modified performance evaluation method(PS) effectively reduces attribute numbers and facilitates the overall assessment. To avoid possible misleading results in the root mean square error-based validations, another indicator called HH(indicating the two authors) is also calculated to guarantee the consistency of the results. The widely used Tolman and Chalikov(TC) package is still generally efficient in determining the integral properties of wave spectra but is physically deficient in explaining the dissipation processes. The ST4 package performs well in overall wave parameters and significantly improves the accuracy of wave systems in the open ocean. Meanwhile, the newly published ST6 package is slightly better in determining swell energy variations. The two packages(ACC350 and BJA) obtained from Wavewatch III v3.14 exhibit large scatters at different sea states. The three most ideal packages are further examined in terms of reproducing waveinduced momentum flux from the perspective of transport. Stokes transport analysis indicates that ST4 is the closest to the NDBC-buoy-spectrum-based transport values, and TC and ST6 tend to overestimate and underestimate the transport magnitude, respectively, in swell mixed areas. This difference must be considered,particularly in air–wave–current coupling research and upper ocean analysis. The assessment results provide guidance for the selection of ST4 for use in a background Pacific Ocean hindcast for high wave climate research and China Sea swell type analysis.展开更多
The effects of sea-surface waves and ocean spray on the marine atmospheric boundary layer(MABL) at different wind speeds and wave ages were investigated. An MABL model was developed that introduces a wave-induced comp...The effects of sea-surface waves and ocean spray on the marine atmospheric boundary layer(MABL) at different wind speeds and wave ages were investigated. An MABL model was developed that introduces a wave-induced component and spray force to the total surface stress. The theoretical model solution was determined assuming the eddy viscosity coefficient varied linearly with height above the sea surface. The wave-induced component was evaluated using a directional wave spectrum and growth rate. Spray force was described using interactions between ocean-spray droplets and wind-velocity shear. Wind profiles and sea-surface drag coefficients were calculated for low to high wind speeds for wind-generated sea at different wave ages to examine surface-wave and ocean-spray effects on MABL momentum distribution. The theoretical solutions were compared with model solutions neglecting wave-induced stress and/or spray stress. Surface waves strongly affected near-surface wind profiles and sea-surface drag coefficients at low to moderate wind speeds. Drag coefficients and near-surface wind speeds were lower for young than for old waves. At high wind speeds, ocean-spray droplets produced by wind-tearing breaking-wave crests affected the MABL strongly in comparison with surface waves, implying that wave age affects the MABL only negligibly. Low drag coefficients at high wind caused by ocean-spray production increased turbulent stress in the sea-spray generation layer, accelerating near-sea-surface wind. Comparing the analytical drag coefficient values with laboratory measurements and field observations indicated that surface waves and ocean spray significantly affect the MABL at different wind speeds and wave ages.展开更多
By introducing a wave-induced component and a spray-induced component to the total stress, a mathematical model based on the Ekman theory is proposed to detail the influence of wind-driven waves and ocean spray on the...By introducing a wave-induced component and a spray-induced component to the total stress, a mathematical model based on the Ekman theory is proposed to detail the influence of wind-driven waves and ocean spray on the momentum transport in a marine atmosphere boundary layer(MABL). An analytic solution of the modified Ekman model can be obtained. The effect of the wave-induced stress is evaluated by a wind wave spectrum and a wave growth rate. It is found that the wave-induced stress and spray stress have a small impact compared with the turbulent stress on the drag coefficient and the wind profiles for low-to-medium wind speed. The spray contribution to the surface stress should be much more taken into account than the winddriven waves when the wind speed reaches above 25 m/s through the action of a "spray stress". As a result, the drag coefficient starts to decrease with increasing wind speed for high wind speed. The effects of the winddriven waves and spray droplets on the near-surface wind profiles are illustrated for different wave ages, which indicates that the production of the spray droplets leads the wind velocity to increase in the MABL. The solutions are also compared with the existed field observational data. Illustrative examples and the comparisons between field observations and the theoretical solutions demonstrate that the spray stress has more significant effect on the marine atmosphere boundary layer in the condition of the high wind speed compared with wave-induced stress.展开更多
The content of organic carbon(OC) normalized to the specific surface area(SSA) of sediment is widely used to trace variations in OC loading(OC/SSA).This study presents observations of OC/SSA of surface sediments colle...The content of organic carbon(OC) normalized to the specific surface area(SSA) of sediment is widely used to trace variations in OC loading(OC/SSA).This study presents observations of OC/SSA of surface sediments collected in the Chukchi Sea,a typical Arctic marginal sea.Shelf sediments exhibit much higher OC/SSA values than slope sediments in the study area.Compared with OC/SSA values reported from the East Siberian Shelf and Mackenzie River,the slope sediments possess lower OC loading.This abrupt decrease in OC/SSA is mostly related to the lower primary production on slope as well as possible oxidization processes.The results of linear regression analysis between OC and SSA indicate a sedimentary source rock for the OC in the Chukchi Sea sediments.Moreover,shelf sediments with low SSA possess a larger rock OC fraction than slope sediments do.The dataset of the present study enables a more thorough understanding of regional OC cycling in the Chukchi Sea.展开更多
Based on the simulation with SWAN wave model and data of ERA-Interim from 1979 to 2016, how the waves propagate globally and why swell pools distribute in the eastern ocean were investigated in this study. The simulat...Based on the simulation with SWAN wave model and data of ERA-Interim from 1979 to 2016, how the waves propagate globally and why swell pools distribute in the eastern ocean were investigated in this study. The simulation results show that waves from North Pacific and North Atlantic mainly propagate southeastward or southward and swells generated in Southern Ocean spread northeastward. The waves from high latitude regions spread along the east coast and encounter in the tropical Pacific and Atlantic to form swell fronts around equator and then turn eastward. As the weak wind field with numerous swell inflows, swell pools are gener- ally located on the eastern side of the ocean basin, where the swell index S are greater than 0.9 calculated using ERA-20C data for the period of 1981 2010. Another remarkable feature is that swell pools move southward and split into two parts in winter, while they move northward and merge together in summer.展开更多
Knowledge of the surface ocean dynamics and the underlying controlling mechanisms is critical to understand the natural variability of the ocean and to predict its future response to climate change.In this paper,we hi...Knowledge of the surface ocean dynamics and the underlying controlling mechanisms is critical to understand the natural variability of the ocean and to predict its future response to climate change.In this paper,we highlight the potential use of Volunteer Observing Ship(VOS),as carrier for automatic underway measuring system and as platform for sample collection,to enhance the observing capacity for the surface ocean.We review the concept,history,present status and future development of the VOS-based in situ surface ocean observation.The successes of various VOS projects demonstrate that,along with the rapid advancing sensor techniques,VOS is able to improve the temporal resolution and spatial coverage of the surface ocean observation in a highly cost-effective manner.A sustained and efficient marine monitoring system in the future should integrate the advantages of various observing platforms including VOS.展开更多
A non-hydrostatic, Boussinesq, and three-dimensional large eddy simulation(LES) model was used to study the impact of the Earth's rotation on turbulence and the redistribution of energy in turbulence kinetic energ...A non-hydrostatic, Boussinesq, and three-dimensional large eddy simulation(LES) model was used to study the impact of the Earth's rotation on turbulence and the redistribution of energy in turbulence kinetic energy(TKE) budget. A set of numerical simulations was conducted,(1) with and without rotation,(2) at different latitudes(10°N, 30°N, 45°N, 60°N, and 80°N),(3) with wave breaking and with Langmuir circulation, and(4) under different wind speeds(5, 10, 20, and 30 m/s). The results show that eddy viscosity decreases when rotation is included, indicating that rotation weakens the turbulence strength. The TKE budget become tight with rotation and the effects of rotation grow with latitude. However, rotation become less important under Langmuir circulation since the transport term is strong in the vertical direction. Finally, simulations were conducted based on field data from the Boundary Layer and Air-Sea Transfer Low Wind(CBLAST-Low) experiment. The results, although more complex, are consistent with the results obtained from earlier simulations using ideal numerical conditions.展开更多
This study explores the influence of Stokes drift and the thermal effects on the upper ocean bias which occurs in the summer with overestimated sea surface temperature(SST)and shallower mixed layer depth(MLD)using Mel...This study explores the influence of Stokes drift and the thermal effects on the upper ocean bias which occurs in the summer with overestimated sea surface temperature(SST)and shallower mixed layer depth(MLD)using Mellor-Yamada turbulence closure scheme.The upper ocean thermal structures through Princeton ocean model are examined by experiments in the cases of idealized forcing and real observational situation.The results suggest that Stokes drift can generally enhance turbulence kinetic energy and deepen MLD either in summer or in winter.This effect will improve the simulation results in summer,but it will lead to much deeper MLD in winter compared to observational data.It is found that MLD can be correctly simulated by combining Stokes drift and the thermal effects of the cool skin layer and diurnal warm layer on the upper mixing layer.In the case of high shortwave radiation and weak wind speed,which usually occurs in summer,the heat absorbed from sun is blocked in the warm layer and prevented from being transferred downwards.As a result,the thermal effects in summer nearly has no influence on dynamic effect of Stokes drift that leads to deepening MLD.However,when the stratification is weak in winter,the thermal effects will counteract the dynamic effect of Stokes drift through enhancing the strength of stratification and suppress mixing impact.Therefore,the dynamic and thermal effects should be considered simultaneously in order to correctly simulate upper ocean thermal structures in both summer and winter.展开更多
A summer-time shipboard meteorological survey is described in the Northwest Indian Ocean. Shipboard observations are used to evaluate a satellite-based sea surface temperature(SST), and then find the main factors that...A summer-time shipboard meteorological survey is described in the Northwest Indian Ocean. Shipboard observations are used to evaluate a satellite-based sea surface temperature(SST), and then find the main factors that are highly correlated with errors. Two satellite data, the first is remote sensing product of a microwave, which is a Tropical Rainfall Measuring Mission Microwave Imager(TMI), and the second is merged data from the microwave and infrared satellite as well as drifter observations, which is Operational Sea Surface Temperature and Sea Ice Analysis(OSTIA). The results reveal that the daily mean SST of merged data has much lower bias and root mean square error as compared with that from microwave products. Therefore the results support the necessary of the merging infrared and drifter SST with a microwave satellite for improving the quality of the SST. Furthermore, the correlation coefficient between an SST error and meteorological parameters, which include a wind speed, an air temperature, a relative humidity, an air pressure, and a visibility. The results show that the wind speed has the largest correlation coefficient with the TMI SST error. However, the air temperature is the most important factor to the OSTIA SST error. Meanwhile,the relative humidity shows the high correlation with the SST error for the OSTIA product.展开更多
Many typhoons pass through the East China Sea(ECS)and the oceanic responses to typhoons on the ECS shelf are very energetic.However,these responses are not well studied because of the complicated background oceanic en...Many typhoons pass through the East China Sea(ECS)and the oceanic responses to typhoons on the ECS shelf are very energetic.However,these responses are not well studied because of the complicated background oceanic environment.The sea surface temperature(SST)response to a severe Typhoon Rananim in August 2004 on the ECS shelf was observed by the merged cloud-penetrating microwave and infrared SST data.The observed SST response shows an extensive SST cooling with a maximum cooling of 3°C on the ECS shelf and the SST cooling lags the typhoon by about one day.A numerical model is designed to simulate the oceanic responses to Rananim.The numerical model reasonably simulates the observed SST response and thereby provides a more comprehensive investigation on the oceanic temperature and current responses.The simulation shows that Rananim deepens the ocean mix layer by more than 10 m on the ECS shelf and causes a cooling in the whole mixed layer.Both upwelling and entrainment are responsible for the cooling.Rananim significantly deforms the background Taiwan Warm Current on the ECS shelf and generates strong Ekman current at the surface.After the typhoon disappears,the surface current rotates clockwise and vertically,the current is featured by near inertial oscillation with upward propagating phase.展开更多
Traditionally fermented shrimp paste has a long fermentation period and is susceptible of external factors,which leads to unstable quality and limits its development and application.Therefore,the purpose of this study...Traditionally fermented shrimp paste has a long fermentation period and is susceptible of external factors,which leads to unstable quality and limits its development and application.Therefore,the purpose of this study is to analyze the flavor changes in the shrimp paste fermentation process and screen out the key volatile aroma components in the shrimp paste to control the flavor quality of the shrimp paste products.The overall odor profile was detected by the electronic nose.A total of 106 volatile flavor compounds in the shrimp paste samples at different fermentation stages were identified by solid-phase microextraction-gas chromatography-mass spectrometry(SPME-GC-MS)and headspace-gas chromatography-ion mobility spectrometry(HS-GC-IMS).The main aroma components alcohols,aldehydes,pyrazines and other substances in the fermentation process showed an overall upward trend.A total of 17 key volatile aroma components in shrimp paste at different fermentation stages were identified by the relative aroma activity value(ROAV)method.The combination of electronic nose,SPME-GC-MS and HS-GC-IMS could comprehensively reflect the changes of volatile components in shrimp paste at different fermentation stages,which helps to further understand the mechanism of shrimp paste flavor formation and provides a basis for the regulation of the flavor quality of shrimp paste products.展开更多
Shrimp sauce,one of the traditional salt-fermented food in China,has a unique flavor that is influenced by the resident microflora.The quality of salt-fermented shrimp sauce was evaluated in this work by determining t...Shrimp sauce,one of the traditional salt-fermented food in China,has a unique flavor that is influenced by the resident microflora.The quality of salt-fermented shrimp sauce was evaluated in this work by determining the total volatile basic nitrogen(TVB-N),the amino acid nitrogen(AAN),organic acid,5’-nucleotide and free amino acids(FAA).Moreover,the dynamics of microbial diversity during processing was investigated by using high-throughput sequencing technology.The results showed that the AAN,TVB-N,organic acid,5’-nucleotide and FAA content were in range of 0.93-1.42 g/100 mL,49.91-236.27 mg/100 mL,6.65-20.68 mg/mL,3.51-6.56 mg/mL and 81.27-102.90 mg/mL.Among the microbial diversity found in the shrimp sauce,Tetragenococcus,Flavobacterium,Polaribacter,Haematospirillum and Staphylococcus were the predominant genera.Correlation analysis indicated that the bacteria Tetragenococcus and Staphylococcus were important in the formation of non-volatile compounds.Tetragenococcus positively correlated with a variety of FAAs;Staphylococcus positively correlated with 5’-nucleotides.The analysis indicated that Tetragenococcus and Staphylococcus were the core genera affecting non-volatile components.These findings indicate the dynamics of the bacterial community and non-volatile components inter-relationships during shrimp sauce fermentation and provide a theoretical basis for improving the fermentation process of shrimp sauce.展开更多
Pipelines are widely used for transporting oil resources in the context of offshore oil exploitation.The pipeline stress-strength analysis is an important stage in related design and ensuing construction techniques.In...Pipelines are widely used for transporting oil resources in the context of offshore oil exploitation.The pipeline stress-strength analysis is an important stage in related design and ensuing construction techniques.In this study,assuming representative work environment parameters,pipeline lifting operations are investigated numerically.More specifically,a time-domain coupled dynamic analysis method is used to conduct a hydrodynamic analysis under different current velocities and wave heights.The results show that proper operation requires the lifting points are reasonably set in combination with the length of the pipeline and the position of the lifting device on the construction ship.The impact of waves on the pipeline is limited,however lifting operations under strong wind and waves should be avoided as far as possible.展开更多
Water jets are widely used in seabed scouring and desilting applications.In the present work,dedicated tests have been conducted using a jet scour model test platform and sand beds containing grains with different siz...Water jets are widely used in seabed scouring and desilting applications.In the present work,dedicated tests have been conducted using a jet scour model test platform and sand beds containing grains with different sizes.The FLOW-3D simulation software has also been used to tackle the problem form a numerical point of view.The boundary conditions of the simulation have been optimized to reduce the gap between the numerical results and the outcomes of the experimental tests.Scour area calculation has been based on a RNG k-εTurbulence model.Moreover,the FAVOR(Fractional Area Volume Obstacle Representation)technology has been selected for grid division to make the simulation results more accurate.Jet scours with inclination angles of 10–20°have been simulated.It has been found that jet scouring is greatly affected by the environmental water flow,that is,water flow can weaken the scouring capacity of the jets.展开更多
In this paper,the scale effect of Kappel tip-rake propellers with different end plate designs was studied using computational fluid dynamics.Given the base size of the mesh and the appropriate numerical model for the ...In this paper,the scale effect of Kappel tip-rake propellers with different end plate designs was studied using computational fluid dynamics.Given the base size of the mesh and the appropriate numerical model for the determined simulation,the open-water performance of three Kappel propellers with different bending degrees of the end plate at different scales was calculated.Comparing the scale effect of these propellers,the scale effect of the torque coefficient of a Kappel propeller is more intense than that of the conventional propeller.In addition,the scale effect of the torque coefficient is strong when the bending degree of the end plate increases,dwarfing the scale effect on the thrust coefficient.Following the research on the scale effect of the wake field for the Kappel propeller,the laws that reveal the influence of the scale on the wake field were summarized;that is,the high-speed zone in the wake relatively expands with the increase of the scale in company with a trend of tip cross flow.The research reveals the basic variation trend and rule of the open-water performance and wake distribution for the Kappel propeller under different scales within the Reynolds number range of 4.665×10^(5)-8.666×10^(7)consideringγtransition,as well as the characteristic differences between the Kappel propellers with different end plate designs,which will be of great significance to its optimization design and application to marine vehicles of different scales.展开更多
A new anchor-siphon drainage combined method used for slope stabilization is proposed in this paper.It includes an anchoring section and a siphon drainage section.The novelty of the anchor-siphon drainage combined met...A new anchor-siphon drainage combined method used for slope stabilization is proposed in this paper.It includes an anchoring section and a siphon drainage section.The novelty of the anchor-siphon drainage combined method is the realization of the drainage and anchoring in the one inclined borehole.The engineering cost of drilling and the resulting disturbance to the slope is reduced.To validate the feasibility of the proposed method,a numerical method that combines the pore water pressure distribution after siphon drainage and the anchoring force of the anchoring section is used to evaluate the safety of the slope with the anchor-siphon drainage method.The proposed method was illustrated and validated with the Hongpu Village landslide,in Tonglu County,Zhejiang Province,in China.Compared with the common anchor bar with the same length in the anchoring section,the factor of safety(FOS)for Hongpu Village slope with anchorsiphon drainage is increased by 0.085.The calculation method of the optimal length ratio between the drainage section and the anchoring section and its influencing factors were studied.For the different design parameters,there is always an optimal length ratio of the drainage section.Compared with the siphon drainage and full-length anchor bar with the same borehole length,the anchor-siphon drainage combined method shows better landslide prevention ability.Moreover,when the optimized parameters with a bond strength of 560kPa,a borehole inclination of 35°,and no reduction in length are used,the calculated safety factor is 1.316,which is significantly higher than the FOS of 1.131 for the slope with siphon drainage.展开更多
Using observational data from multiple satellites,we studied seasonal variations of the shape and location of the Luzon cold eddy(LCE)northwest of Luzon Island.The shape and location of the LCE have obvious seasonal v...Using observational data from multiple satellites,we studied seasonal variations of the shape and location of the Luzon cold eddy(LCE)northwest of Luzon Island.The shape and location of the LCE have obvious seasonal variations.The LCE occurs,develops,and disappears from December to April of the next year.During this period,the shape of the LCE changed from a flat ellipse to a circular ellipse,and the change in shape can be reflected by the increase of the ellipticity of the LCE from 0.16 to 0.82.The latitude of center location of the LCE changes from 17.4°N to 19°N,and the change in latitude can reach 1.6°.Further study showed that seasonal variation of the northeast monsoon intensity leads to the change in the shape and location of the LCE.The seasonal variation of the LCE shape can significantly alter the spatial distribution of the thermal front and chlorophyll a northwest of the Luzon Island by geostrophic advection.展开更多
基金supported by the Scientific and Technological Research and Development Programs of China Railway Group Limited(Grant No.2022 Major Special Project-07)Gansu Provincial Technology Innovation Guidance Program-Special Funding for Capacity Building of Enterprise R&D Institutions(Grant No.23CXJA0011)Key R&D and transformation plan of Qinghai Province,China(Special Project for Transformation of Scientific and Technological Achievements No.2022-SF-158).
文摘In the actual monitoring of deep hole displacement,the identification of slip surfaces is primarily based on abrupt changes observed in the inclinometric curve.In conventional identification methods,inclinometric curves exhibiting indications of sliding can be categorized into three types:B-type,D-type,and r-type.The position of the slip surface is typically determined by identifying the depth corresponding to the point of maximum displacement mutation.However,this method is sensitive to the interval of measurement points and the observation scale of the coordinate axes and suffers from unclear sliding surfaces and uncertain values.Based on the variation characteristics of these diagonal curves,we classified the landslide into three components:the sliding body,the sliding interval,and the immobile body.Moreover,three different generalization models were established to analyze the relationships between the curve form and the slip surface location based on different physical indicators such as displacement rate,relative displacement,and acceleration.The results show that the displacement rate curves of an r-type slope exhibit a clustering feature in the sliding interval,and by solving for the depth of discrete points within the step phase,it is possible to determine the location of the slip surface.On the other hand,D-type slopes have inflection points in the relative displacement curve located at the slip surface.The acceleration curves of B-type slopes exhibit clustering characteristics during the sliding interval,while the scattered acceleration data demonstrate wandering characteristics.Consequently,the slip surface location can be revealed by solving the depth corresponding to the maximum acceleration with cubic spline interpolation.The approach proposed in this paper was applied to the monitoring data of a landslide in Yunnan Province,China.The results indicate that our approach can accurately identify the slip surface location and enable computability of its position,thereby enhancing applicability and reliability of the deep-hole displacement monitoring data.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.51775077 and 51909023)。
文摘Shear-thinning fluids have been widely used in microfluidic systems,but their internal flow mechanism is still unclear.Therefore,in this paper,molecular dynamics simulations are used to study the laminar flow of shear-thinning fluid in a microchannel.We validated the feasibility of our simulation method by evaluating the mean square displacement and Reynolds number of the solution layers.The results show that the change rule of the fluid system's velocity profile and interaction energy can reflect the shear-thinning characteristics of the fluids.The velocity profile resembles a top-hat shape,intensifying as the fluid's power law index decreases.The interaction energy between the wall and the fluid decreases gradually with increasing velocity,and a high concentration of non-Newtonian fluid reaches a plateau sooner.Moreover,the velocity profile of the fluid is related to the molecule number density distribution and their values are inversely proportional.By analyzing the radial distribution function,we found that the hydrogen bonds between solute and water molecules weaken with the increase in velocity.This observation offers an explanation for the shear-thinning phenomenon of the non-Newtonian flow from a micro perspective.
基金The National High Technology Research and Development Program(863 Program) of China under contract No.2013AA122803the Strategic Priority Research Program of the Chinese Academy of Sciences under contract No.XDA11010104
文摘Wave climate analysis and other applications for the Pacific Ocean require a reliable wave hindcast. Five source and sink term packages in the Wavewatch III model(v3.14 and v4.18) are compared and assessed in this study through comprehensive observations, including altimeter significant wave height, advanced synthetic aperture radar swell, and buoy wave parameters and spectrum. In addition to the evaluation of typically used integral parameters, the spectra partitioning method contributes to the detailed wave system and wave maturity validation. The modified performance evaluation method(PS) effectively reduces attribute numbers and facilitates the overall assessment. To avoid possible misleading results in the root mean square error-based validations, another indicator called HH(indicating the two authors) is also calculated to guarantee the consistency of the results. The widely used Tolman and Chalikov(TC) package is still generally efficient in determining the integral properties of wave spectra but is physically deficient in explaining the dissipation processes. The ST4 package performs well in overall wave parameters and significantly improves the accuracy of wave systems in the open ocean. Meanwhile, the newly published ST6 package is slightly better in determining swell energy variations. The two packages(ACC350 and BJA) obtained from Wavewatch III v3.14 exhibit large scatters at different sea states. The three most ideal packages are further examined in terms of reproducing waveinduced momentum flux from the perspective of transport. Stokes transport analysis indicates that ST4 is the closest to the NDBC-buoy-spectrum-based transport values, and TC and ST6 tend to overestimate and underestimate the transport magnitude, respectively, in swell mixed areas. This difference must be considered,particularly in air–wave–current coupling research and upper ocean analysis. The assessment results provide guidance for the selection of ST4 for use in a background Pacific Ocean hindcast for high wave climate research and China Sea swell type analysis.
基金supported by the National Natural Science Foundation of China (Grant No. 41576013)the National Key Research and Development Program of China (Grant No. 2016YFC1401404)+1 种基金supported by the National Natural Science Foundation of China (Grant No. 41476021 and 41621064)the Indo-Pacific Ocean Environment Variation and Air–Sea Interaction project (GASI-IPOVAI-04)
文摘The effects of sea-surface waves and ocean spray on the marine atmospheric boundary layer(MABL) at different wind speeds and wave ages were investigated. An MABL model was developed that introduces a wave-induced component and spray force to the total surface stress. The theoretical model solution was determined assuming the eddy viscosity coefficient varied linearly with height above the sea surface. The wave-induced component was evaluated using a directional wave spectrum and growth rate. Spray force was described using interactions between ocean-spray droplets and wind-velocity shear. Wind profiles and sea-surface drag coefficients were calculated for low to high wind speeds for wind-generated sea at different wave ages to examine surface-wave and ocean-spray effects on MABL momentum distribution. The theoretical solutions were compared with model solutions neglecting wave-induced stress and/or spray stress. Surface waves strongly affected near-surface wind profiles and sea-surface drag coefficients at low to moderate wind speeds. Drag coefficients and near-surface wind speeds were lower for young than for old waves. At high wind speeds, ocean-spray droplets produced by wind-tearing breaking-wave crests affected the MABL strongly in comparison with surface waves, implying that wave age affects the MABL only negligibly. Low drag coefficients at high wind caused by ocean-spray production increased turbulent stress in the sea-spray generation layer, accelerating near-sea-surface wind. Comparing the analytical drag coefficient values with laboratory measurements and field observations indicated that surface waves and ocean spray significantly affect the MABL at different wind speeds and wave ages.
基金The National Natural Science Foundations of China under contract Nos 41576013 and 11362012the National High Technology Research and Development Program(863 Program)of China under contract No.2013AA122803the Strategic Priority Research Program of the Chinese Academy of Sciences under contract No.XDA11010104
文摘By introducing a wave-induced component and a spray-induced component to the total stress, a mathematical model based on the Ekman theory is proposed to detail the influence of wind-driven waves and ocean spray on the momentum transport in a marine atmosphere boundary layer(MABL). An analytic solution of the modified Ekman model can be obtained. The effect of the wave-induced stress is evaluated by a wind wave spectrum and a wave growth rate. It is found that the wave-induced stress and spray stress have a small impact compared with the turbulent stress on the drag coefficient and the wind profiles for low-to-medium wind speed. The spray contribution to the surface stress should be much more taken into account than the winddriven waves when the wind speed reaches above 25 m/s through the action of a "spray stress". As a result, the drag coefficient starts to decrease with increasing wind speed for high wind speed. The effects of the winddriven waves and spray droplets on the near-surface wind profiles are illustrated for different wave ages, which indicates that the production of the spray droplets leads the wind velocity to increase in the MABL. The solutions are also compared with the existed field observational data. Illustrative examples and the comparisons between field observations and the theoretical solutions demonstrate that the spray stress has more significant effect on the marine atmosphere boundary layer in the condition of the high wind speed compared with wave-induced stress.
基金The National Natural Science Foundation of China under contract Nos 41606211,41276198,41406217 and 41306200the China Polar Environment Comprehensive Investigation and Assessment Programs under contract Nos Chinare-03-04 and Chinare-04-03+1 种基金the National Science Foundation for Post-doctoral Scientists of China under contract No.2016M591968the Scientific Research Fund of Second Institute of Oceanography,SOA under contract No.JG1502
文摘The content of organic carbon(OC) normalized to the specific surface area(SSA) of sediment is widely used to trace variations in OC loading(OC/SSA).This study presents observations of OC/SSA of surface sediments collected in the Chukchi Sea,a typical Arctic marginal sea.Shelf sediments exhibit much higher OC/SSA values than slope sediments in the study area.Compared with OC/SSA values reported from the East Siberian Shelf and Mackenzie River,the slope sediments possess lower OC loading.This abrupt decrease in OC/SSA is mostly related to the lower primary production on slope as well as possible oxidization processes.The results of linear regression analysis between OC and SSA indicate a sedimentary source rock for the OC in the Chukchi Sea sediments.Moreover,shelf sediments with low SSA possess a larger rock OC fraction than slope sediments do.The dataset of the present study enables a more thorough understanding of regional OC cycling in the Chukchi Sea.
基金financially supported by the Public Science and Technology Research Funds Projects of Ocean (No. 201505007)the National Natural Science Foundation of China (NSFC) (No. 41276015)+2 种基金the Joint Project for the National Oceanographic Center by the NSFC and Shandong Government (No. U1406401)the Doctoral Fund of Ministry of Education of China (No. 20120132110004)the Hebei Agricultural University research project for talented scholars (No. YJ201835)
文摘Based on the simulation with SWAN wave model and data of ERA-Interim from 1979 to 2016, how the waves propagate globally and why swell pools distribute in the eastern ocean were investigated in this study. The simulation results show that waves from North Pacific and North Atlantic mainly propagate southeastward or southward and swells generated in Southern Ocean spread northeastward. The waves from high latitude regions spread along the east coast and encounter in the tropical Pacific and Atlantic to form swell fronts around equator and then turn eastward. As the weak wind field with numerous swell inflows, swell pools are gener- ally located on the eastern side of the ocean basin, where the swell index S are greater than 0.9 calculated using ERA-20C data for the period of 1981 2010. Another remarkable feature is that swell pools move southward and split into two parts in winter, while they move northward and merge together in summer.
基金The National Basic Research Program of China under contract Nos 201 1CB403501 and 2012CB417402the Fund for Creative Research Groups by the National Natural Science Foundation of China under contract No.41121064+1 种基金the National Natural Science Foundation of China under contract Nos 41206015 and 41176016the Open Research Foundation for the State Key Laboratory of Satellite Ocean Environment Dynamics,Second Institute of Oceanography,State Oceanic Administration under contract No.SOED1210
基金The National Natural Science Foundation of China under contract No.41506090the National Key Research and Development Program of China under contract No.2016YFA0601400the Key Laboratory of Global Change and Marine-Atmospheric Chemistry under contract No.GCMAC1408
文摘Knowledge of the surface ocean dynamics and the underlying controlling mechanisms is critical to understand the natural variability of the ocean and to predict its future response to climate change.In this paper,we highlight the potential use of Volunteer Observing Ship(VOS),as carrier for automatic underway measuring system and as platform for sample collection,to enhance the observing capacity for the surface ocean.We review the concept,history,present status and future development of the VOS-based in situ surface ocean observation.The successes of various VOS projects demonstrate that,along with the rapid advancing sensor techniques,VOS is able to improve the temporal resolution and spatial coverage of the surface ocean observation in a highly cost-effective manner.A sustained and efficient marine monitoring system in the future should integrate the advantages of various observing platforms including VOS.
基金Supported by the National Natural Science Foundation of China(Nos.41206015,41106019)the National Basic Research Program of China(973 Program)(Nos.2011CB403501,2012CB417402)the Fund for Creative Research Groups by NSFC(No.41121064)
文摘A non-hydrostatic, Boussinesq, and three-dimensional large eddy simulation(LES) model was used to study the impact of the Earth's rotation on turbulence and the redistribution of energy in turbulence kinetic energy(TKE) budget. A set of numerical simulations was conducted,(1) with and without rotation,(2) at different latitudes(10°N, 30°N, 45°N, 60°N, and 80°N),(3) with wave breaking and with Langmuir circulation, and(4) under different wind speeds(5, 10, 20, and 30 m/s). The results show that eddy viscosity decreases when rotation is included, indicating that rotation weakens the turbulence strength. The TKE budget become tight with rotation and the effects of rotation grow with latitude. However, rotation become less important under Langmuir circulation since the transport term is strong in the vertical direction. Finally, simulations were conducted based on field data from the Boundary Layer and Air-Sea Transfer Low Wind(CBLAST-Low) experiment. The results, although more complex, are consistent with the results obtained from earlier simulations using ideal numerical conditions.
基金The National Natural Science Foundation of China under contract Nos 41876010 and 41276015the Public Science and Technology Research Funds Projects of Ocean under contrct No.201505007+1 种基金the Joint Project for the National Oceanographic Center by the NSFC and Shandong Government under contract No.U1406402the National Natural Science Foundation of China under contract No.41806028。
文摘This study explores the influence of Stokes drift and the thermal effects on the upper ocean bias which occurs in the summer with overestimated sea surface temperature(SST)and shallower mixed layer depth(MLD)using Mellor-Yamada turbulence closure scheme.The upper ocean thermal structures through Princeton ocean model are examined by experiments in the cases of idealized forcing and real observational situation.The results suggest that Stokes drift can generally enhance turbulence kinetic energy and deepen MLD either in summer or in winter.This effect will improve the simulation results in summer,but it will lead to much deeper MLD in winter compared to observational data.It is found that MLD can be correctly simulated by combining Stokes drift and the thermal effects of the cool skin layer and diurnal warm layer on the upper mixing layer.In the case of high shortwave radiation and weak wind speed,which usually occurs in summer,the heat absorbed from sun is blocked in the warm layer and prevented from being transferred downwards.As a result,the thermal effects in summer nearly has no influence on dynamic effect of Stokes drift that leads to deepening MLD.However,when the stratification is weak in winter,the thermal effects will counteract the dynamic effect of Stokes drift through enhancing the strength of stratification and suppress mixing impact.Therefore,the dynamic and thermal effects should be considered simultaneously in order to correctly simulate upper ocean thermal structures in both summer and winter.
基金China Ocean Mineral Resources Research and Development Association Project under contract No.DY125-12-R-03the National Natural Science Foundation of China under contract Nos 41476021 and 41321004the Scientific Research Fund of Second Institute of Oceanography,State Oceanic Administration China under contract No.JT1205
文摘A summer-time shipboard meteorological survey is described in the Northwest Indian Ocean. Shipboard observations are used to evaluate a satellite-based sea surface temperature(SST), and then find the main factors that are highly correlated with errors. Two satellite data, the first is remote sensing product of a microwave, which is a Tropical Rainfall Measuring Mission Microwave Imager(TMI), and the second is merged data from the microwave and infrared satellite as well as drifter observations, which is Operational Sea Surface Temperature and Sea Ice Analysis(OSTIA). The results reveal that the daily mean SST of merged data has much lower bias and root mean square error as compared with that from microwave products. Therefore the results support the necessary of the merging infrared and drifter SST with a microwave satellite for improving the quality of the SST. Furthermore, the correlation coefficient between an SST error and meteorological parameters, which include a wind speed, an air temperature, a relative humidity, an air pressure, and a visibility. The results show that the wind speed has the largest correlation coefficient with the TMI SST error. However, the air temperature is the most important factor to the OSTIA SST error. Meanwhile,the relative humidity shows the high correlation with the SST error for the OSTIA product.
基金The National Natural Science Foundation of China under contract Nos 11572283,11602179 and 41806028the National Key Research and Development Program of China under contract No.2017YFC1403300the Public Science and Technology Research Funds Projects of Ocean under contract No.20110518-5。
文摘Many typhoons pass through the East China Sea(ECS)and the oceanic responses to typhoons on the ECS shelf are very energetic.However,these responses are not well studied because of the complicated background oceanic environment.The sea surface temperature(SST)response to a severe Typhoon Rananim in August 2004 on the ECS shelf was observed by the merged cloud-penetrating microwave and infrared SST data.The observed SST response shows an extensive SST cooling with a maximum cooling of 3°C on the ECS shelf and the SST cooling lags the typhoon by about one day.A numerical model is designed to simulate the oceanic responses to Rananim.The numerical model reasonably simulates the observed SST response and thereby provides a more comprehensive investigation on the oceanic temperature and current responses.The simulation shows that Rananim deepens the ocean mix layer by more than 10 m on the ECS shelf and causes a cooling in the whole mixed layer.Both upwelling and entrainment are responsible for the cooling.Rananim significantly deforms the background Taiwan Warm Current on the ECS shelf and generates strong Ekman current at the surface.After the typhoon disappears,the surface current rotates clockwise and vertically,the current is featured by near inertial oscillation with upward propagating phase.
基金support from the National Key R&D Program of China (2019YFD0901903)the Innovation Team Project of Hebei (Province) Modern Agricultural Industry Technology System (HBCT2018170207)the Postgraduate Research & Practice Innovation Program of Jiangsu Province (SJCX20_1426)
文摘Traditionally fermented shrimp paste has a long fermentation period and is susceptible of external factors,which leads to unstable quality and limits its development and application.Therefore,the purpose of this study is to analyze the flavor changes in the shrimp paste fermentation process and screen out the key volatile aroma components in the shrimp paste to control the flavor quality of the shrimp paste products.The overall odor profile was detected by the electronic nose.A total of 106 volatile flavor compounds in the shrimp paste samples at different fermentation stages were identified by solid-phase microextraction-gas chromatography-mass spectrometry(SPME-GC-MS)and headspace-gas chromatography-ion mobility spectrometry(HS-GC-IMS).The main aroma components alcohols,aldehydes,pyrazines and other substances in the fermentation process showed an overall upward trend.A total of 17 key volatile aroma components in shrimp paste at different fermentation stages were identified by the relative aroma activity value(ROAV)method.The combination of electronic nose,SPME-GC-MS and HS-GC-IMS could comprehensively reflect the changes of volatile components in shrimp paste at different fermentation stages,which helps to further understand the mechanism of shrimp paste flavor formation and provides a basis for the regulation of the flavor quality of shrimp paste products.
基金support from the National Key R&D Program of China (2019YFD0901903)the Innovation Team Project of Hebei (Province) Modern Agricultural Industry Technology System (HBCT2018170207)the Postgraduate Research & Practice Innovation Program of Jiangsu Province (SJCX20_1426)
文摘Shrimp sauce,one of the traditional salt-fermented food in China,has a unique flavor that is influenced by the resident microflora.The quality of salt-fermented shrimp sauce was evaluated in this work by determining the total volatile basic nitrogen(TVB-N),the amino acid nitrogen(AAN),organic acid,5’-nucleotide and free amino acids(FAA).Moreover,the dynamics of microbial diversity during processing was investigated by using high-throughput sequencing technology.The results showed that the AAN,TVB-N,organic acid,5’-nucleotide and FAA content were in range of 0.93-1.42 g/100 mL,49.91-236.27 mg/100 mL,6.65-20.68 mg/mL,3.51-6.56 mg/mL and 81.27-102.90 mg/mL.Among the microbial diversity found in the shrimp sauce,Tetragenococcus,Flavobacterium,Polaribacter,Haematospirillum and Staphylococcus were the predominant genera.Correlation analysis indicated that the bacteria Tetragenococcus and Staphylococcus were important in the formation of non-volatile compounds.Tetragenococcus positively correlated with a variety of FAAs;Staphylococcus positively correlated with 5’-nucleotides.The analysis indicated that Tetragenococcus and Staphylococcus were the core genera affecting non-volatile components.These findings indicate the dynamics of the bacterial community and non-volatile components inter-relationships during shrimp sauce fermentation and provide a theoretical basis for improving the fermentation process of shrimp sauce.
基金This study was financially supported by the Program for Scientific Research Start-Up Funds of Guangdong Ocean University(060302072101)Comparative Study,and Optimization of Horizontal Lifting of Subsea Pipeline(2021E05011).
文摘Pipelines are widely used for transporting oil resources in the context of offshore oil exploitation.The pipeline stress-strength analysis is an important stage in related design and ensuing construction techniques.In this study,assuming representative work environment parameters,pipeline lifting operations are investigated numerically.More specifically,a time-domain coupled dynamic analysis method is used to conduct a hydrodynamic analysis under different current velocities and wave heights.The results show that proper operation requires the lifting points are reasonably set in combination with the length of the pipeline and the position of the lifting device on the construction ship.The impact of waves on the pipeline is limited,however lifting operations under strong wind and waves should be avoided as far as possible.
基金This work is supported by National Nature Fund of China(52071091)the Key Laboratory of Expressway Construction Machinery of Shanxi Province which is gained by Zhang(300102259512).
文摘Water jets are widely used in seabed scouring and desilting applications.In the present work,dedicated tests have been conducted using a jet scour model test platform and sand beds containing grains with different sizes.The FLOW-3D simulation software has also been used to tackle the problem form a numerical point of view.The boundary conditions of the simulation have been optimized to reduce the gap between the numerical results and the outcomes of the experimental tests.Scour area calculation has been based on a RNG k-εTurbulence model.Moreover,the FAVOR(Fractional Area Volume Obstacle Representation)technology has been selected for grid division to make the simulation results more accurate.Jet scours with inclination angles of 10–20°have been simulated.It has been found that jet scouring is greatly affected by the environmental water flow,that is,water flow can weaken the scouring capacity of the jets.
基金Supported by the Ningbo Institute of Materials Technology and Engineering affiliated to Chinese Academy of Sciences(Grant No.829203-I22101)TXC(Ningbo)Co.,Ltd.(Grant No.529203-I22004).
文摘In this paper,the scale effect of Kappel tip-rake propellers with different end plate designs was studied using computational fluid dynamics.Given the base size of the mesh and the appropriate numerical model for the determined simulation,the open-water performance of three Kappel propellers with different bending degrees of the end plate at different scales was calculated.Comparing the scale effect of these propellers,the scale effect of the torque coefficient of a Kappel propeller is more intense than that of the conventional propeller.In addition,the scale effect of the torque coefficient is strong when the bending degree of the end plate increases,dwarfing the scale effect on the thrust coefficient.Following the research on the scale effect of the wake field for the Kappel propeller,the laws that reveal the influence of the scale on the wake field were summarized;that is,the high-speed zone in the wake relatively expands with the increase of the scale in company with a trend of tip cross flow.The research reveals the basic variation trend and rule of the open-water performance and wake distribution for the Kappel propeller under different scales within the Reynolds number range of 4.665×10^(5)-8.666×10^(7)consideringγtransition,as well as the characteristic differences between the Kappel propellers with different end plate designs,which will be of great significance to its optimization design and application to marine vehicles of different scales.
基金the financial support of the National Natural Science Foundation of China(Key Project)(No.42230702)National Natural Science Foundation of China(No.42277129)Natural Science Foundation of Zhejiang Province(No.LY21D020001)。
文摘A new anchor-siphon drainage combined method used for slope stabilization is proposed in this paper.It includes an anchoring section and a siphon drainage section.The novelty of the anchor-siphon drainage combined method is the realization of the drainage and anchoring in the one inclined borehole.The engineering cost of drilling and the resulting disturbance to the slope is reduced.To validate the feasibility of the proposed method,a numerical method that combines the pore water pressure distribution after siphon drainage and the anchoring force of the anchoring section is used to evaluate the safety of the slope with the anchor-siphon drainage method.The proposed method was illustrated and validated with the Hongpu Village landslide,in Tonglu County,Zhejiang Province,in China.Compared with the common anchor bar with the same length in the anchoring section,the factor of safety(FOS)for Hongpu Village slope with anchorsiphon drainage is increased by 0.085.The calculation method of the optimal length ratio between the drainage section and the anchoring section and its influencing factors were studied.For the different design parameters,there is always an optimal length ratio of the drainage section.Compared with the siphon drainage and full-length anchor bar with the same borehole length,the anchor-siphon drainage combined method shows better landslide prevention ability.Moreover,when the optimized parameters with a bond strength of 560kPa,a borehole inclination of 35°,and no reduction in length are used,the calculated safety factor is 1.316,which is significantly higher than the FOS of 1.131 for the slope with siphon drainage.
基金The 2022 Research Program of Sanya Yazhou Bay Science and Technology City under contract No.SKJC-2022-01-001the Project of Sanya Yazhou Bay Science and Technology City under contract No.SCKJ-JYRC-2022-47+4 种基金the National Natural Science Foundation of China under contract No.41806019the Natural Science Foundation of Hainan Province under contract No.121MS062the National Natural Science Foundation of China under contract Nos 42006008 and 41876031the National Key Research and Development Plan of China under contract No.2016YFC1401603the Research Startup Funding from Hainan Institute of Zhejiang University under contract No.HZY20210801。
文摘Using observational data from multiple satellites,we studied seasonal variations of the shape and location of the Luzon cold eddy(LCE)northwest of Luzon Island.The shape and location of the LCE have obvious seasonal variations.The LCE occurs,develops,and disappears from December to April of the next year.During this period,the shape of the LCE changed from a flat ellipse to a circular ellipse,and the change in shape can be reflected by the increase of the ellipticity of the LCE from 0.16 to 0.82.The latitude of center location of the LCE changes from 17.4°N to 19°N,and the change in latitude can reach 1.6°.Further study showed that seasonal variation of the northeast monsoon intensity leads to the change in the shape and location of the LCE.The seasonal variation of the LCE shape can significantly alter the spatial distribution of the thermal front and chlorophyll a northwest of the Luzon Island by geostrophic advection.
