Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,...Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,including bubble,electromagnetic stirring,filtration separation,fluid flow,and sedimentation,often struggle with the removal of fine inclusions.Apart from these known methods,pulsed electric current(PEC),as an emerging technology,has demonstrated immense potential and environmental advantages.PEC offers adjustable current parameters and simple equipment,making it an attractive alternative to traditional methods.Its green energy-saving features and excellent results in regulating inclusion morphology and migration,as well as inhibiting submerged entry nozzle(SEN)clogging,make it a promising technology.In comparison to continuous current technology,PEC has shown significant advantages in regulating inclusions,not only improving purification efficiency but also demonstrating outstanding performance in flow stability and energy consumption.The ability of PEC to efficiently reduce inclusion numbers enhances the purity and quality of molten steel,improving its mechanical properties.Currently,the theoretical basis for controlling the movement of inclusions by current is mainly composed of three major theories:the double electric layer theory,electromagnetic force reverse separation theory,and electric free energy drive theory.These theories together form an important framework for researchers to understand and optimize the behavior of impurity movement controlled by electric current.Looking ahead,PEC is expected to pave the way for new solutions in directional regulation of inclusion migration,efficient inclusion removal,SEN clogging prevention,and the purification of molten steel.展开更多
Colloidal transport and deposition in porous media are complex processes that result from the interaction between hydrodynamics(velocity,pore geometry,etc.)and Derjaguin-Landau-Verwey-Overbeek(DLVO)forces(particle-par...Colloidal transport and deposition in porous media are complex processes that result from the interaction between hydrodynamics(velocity,pore geometry,etc.)and Derjaguin-Landau-Verwey-Overbeek(DLVO)forces(particle-particle and particle-surface).They have important implications for engineering applications involving the reinjection of a fluidinto a medium,such as geothermal energy.The investigation of permeability stability is critical to ensure the sustainability of activities.This work aims to study the clogging mechanisms in a rock-like porous medium using a microfluidicdevice.The pore-throat network distributions reveal that the micromodel geometry mimics real rock samples.The transport of a monodispersed suspension is studied at different concentrations.Image analysis,velocity fieldmodeling,and pressure drop measurement are used to assess preferential clogging sites and porous medium permeability reduction,respectively.Experiments have shown that retention sites are located around preferential flow paths with relatively high flow velocities.When clogged,the pore thresholds are the deposition zones that lead to a reduction in permeability.However,pore bodies may also constitute deposition zones.Interestingly,as the concentration of the suspension increases,the kinetics of the permeability reduction are delayed,and the clogging mechanisms,as well as the type of deposit,evolve.Finally,at very high concentrations,the effects of hydrodynamic stripping are more important.These observations emphasize the role of the porous medium geometry in colloidal transport and deposition and thus permeability reduction.展开更多
Particle transport is a fundamental aspect of various systems,from artificial to biological.A common assumption is that particle motion follows Markovian(memoryless)processes in the absence of interaction between part...Particle transport is a fundamental aspect of various systems,from artificial to biological.A common assumption is that particle motion follows Markovian(memoryless)processes in the absence of interaction between particles.However,hydrodynamic memory and the interaction between particles are ubiquitous,leaving many fundamental questions unanswered regarding transport of interacting particles involving hydrodynamic drag in corrugated channels,as described by the fractional Langevin equation.This study examines the hydrodynamic transport of interacting non-Brownian particles moving within a corrugated channel.We propose a method that relies on factors such as temperature,the driving force to alternate between no transport and finite net transport.Of importance is to note that the absence of transport results from the clogging,while the transport consists of collective motion and independent motion.The transport systems investigated in this work suggest the potential for sensor functionality within the system.Our findings may prove valuable for exploring the transport with hydrodynamic memory in various fields,including biology,physics,and chemistry.展开更多
Understanding the motion behaviors of non-metallic inclusions in the liquid metal is important for clean steel production.High-temperature confocal laser scanning microscopy is applied to investigate the effect of dif...Understanding the motion behaviors of non-metallic inclusions in the liquid metal is important for clean steel production.High-temperature confocal laser scanning microscopy is applied to investigate the effect of different Ti and Al contents on the agglomeration behavior of non-metallic inclusions in low carbon steels.Furthermore,the agglomeration mechanism of inclusions was investigated through quantitative analysis of in-situ observation experiments and a modified Kralchevsky-Paunov model.The obtained results indicate that Al_(2)O_(3)is the main type inclusion in the low-alloys steels with both Al and Ti addition.This type of inclusion is more likely to absorb surrounding small-size inclusion particles,leading to a further growth for the cluster formation and contributing to a serious engineering problem,nozzle clogging.Besides,TiO_(x)is the main type inclusion in the molten steel with only Ti addition,and this type of inclusion is less likely to agglomerate and the individual inclusion particles show a‘free’motion with the fluid of molten steel.The difference between these two types of inclusions is due to the difference in attractive force and action distance at the meniscus created by the inclusion/steel/Ar multiple interfaces and influenced by the physical parameters,e.g.,contact angle and interface energy between inclusion and steel,and surface tension of the melt.展开更多
Microgrinding is widely used in clinical bone surgery,but saline spray cooling faces technical challenges such as low wettability at the microgrinding tool–bone interface,easy clogging of the microgrinding tools,and ...Microgrinding is widely used in clinical bone surgery,but saline spray cooling faces technical challenges such as low wettability at the microgrinding tool–bone interface,easy clogging of the microgrinding tools,and high grinding temperatures.These issues can lead to bone necrosis,irreversible thermal damage to nerves,or even surgical failure.Inspired by the water-trapping and directional transportation abilities of desert beetles,this study proposes a biomimetic desert beetle microgrinding tool.The flow-field distribution directly influences the convective heat transfer of the cooling medium in the grinding zone,which in turn affects the grinding temperature.To address this,a mathematical model of the two-phase flow field at the biomimetic microgrinding tool–bone interface is developed.The results indicate an average error of 14.74%between the calculated and experimentally obtained airflow field velocities.Next,a biomimetic desert beetle microgrinding tool is prepared.Experiments with physiological saline spray cooling were conducted on fresh bovine femur bone,which has mechanical properties similar to human bone.Results show that,compared with conventional microgrinding tools,the biomimetic tools reduced bone surface temperature by 21.7%,13.2%,5.8%,20.3%,and 25.8%at particle sizes of 150#,200#,240#,270#,and 300#,respectively.The surface morphology of the biomimetic microgrinding tools after grinding is observed and analyzed,revealing a maximum clogging area reduction of 23.0%,which is 6.1%,6.0%,10.0%,15.6%,and 9.5%less than that observed with conventional tools.Finally,this study unveils the dynamic mechanism of cooling medium transfer in the flow field at the biomimetic microgrinding tool–bone interface.This research provides theoretical guidance and technical support for clinical bone resection surgery.展开更多
Managed Aquifer Recharge(MAR)is a strategic approach to artificially replenishing groundwater supplies and has become an integral component of global water resource management.The number of MAR projects has steadily i...Managed Aquifer Recharge(MAR)is a strategic approach to artificially replenishing groundwater supplies and has become an integral component of global water resource management.The number of MAR projects has steadily increased in recent decades,yet many have failed to achieved their intended outcomes,underscoring the complexity of project implementation.This review is dedicated to examine existing research and reports on MAR performance and impacts,aiming to establish objective criteria for gauging the success and identify key factors influencing the effectiveness of MAR project.Five critical performance factors have been identified as major determinants of MAR performance:aquifer transmissivity,vertical permeability,availability of recharge water,recharge water quality,and aquifer thickness,geometry and boundary conditions.These factors are directly related to project success and significantly shape MAR outcomes.In addition,this review explores research-based strategies to improve MAR success,including cutting-edge methodologies,technological innovations,and integrated management approaches to address key challenges.The ultimate goal is to foster more efficient,effective,and sustainable MAR practices,thereby enhancing the resilience and sustainability of water resource management.展开更多
To fundamentally alleviate the excavation chamber clogging during slurry tunnel boring machine(TBM)advancing in hard rock,large-diameter short screw conveyor was adopted to slurry TBM of Qingdao Jiaozhou Bay Second Un...To fundamentally alleviate the excavation chamber clogging during slurry tunnel boring machine(TBM)advancing in hard rock,large-diameter short screw conveyor was adopted to slurry TBM of Qingdao Jiaozhou Bay Second Undersea Tunnel.To evaluate the discharging performance of short screw conveyor in different cases,the full-scale transient slurry-rock two-phase model for a short screw conveyor actively discharging rocks was established using computational fluid dynamics-discrete element method(CFD-DEM)coupling approach.In the fluid domain of coupling model,the sliding mesh technology was utilized to describe the rotations of the atmospheric composite cutterhead and the short screw conveyor.In the particle domain of coupling model,the dynamic particle factories were established to produce rock particles with the rotation of the cutterhead.And the accuracy and reliability of the CFD-DEM simulation results were validated via the field test and model test.Furthermore,a comprehensive parameter analysis was conducted to examine the effects of TBM operating parameters,the geometric design of screw conveyor and the size of rocks on the discharging performance of short screw conveyor.Accordingly,a reasonable rotational speed of screw conveyor was suggested and applied to Jiaozhou Bay Second Undersea Tunnel project.The findings in this paper could provide valuable references for addressing the excavation chamber clogging during ultra-large-diameter slurry TBM tunneling in hard rock for similar future.展开更多
[Objective] The aim was to al eviate the constructed wetland clogging problems and to explore to the effects of hydraulic loading on wetland clogging. [Method] The experiment, through artificial soil columns, simulate...[Objective] The aim was to al eviate the constructed wetland clogging problems and to explore to the effects of hydraulic loading on wetland clogging. [Method] The experiment, through artificial soil columns, simulated vertical flow arti-ficial wetland, set four hydraulic load level at 50, 100, 150 and 200 cm/d, to identify the impact of hydraulic loading on wetland clogging and to explore the factors run-ning threshold. [Result] The results show that the different levels of hydraulic loading have greater impact; in the constructed wetland clogging process under high hy-draulic loading of 200 cm/d, the effective life was only six months, and the single factor can be speculated that the threshold of the hydraulic load should be at 100-150 cm/d; system can last for six months at low hydraulic loading and last for three months at medium hydraulic load. [Conclusion] The research provides references for wetland clogging experiments in future.展开更多
The accumulation of organic matter in substratum pores is regarded as an important factor causing clogging separately in the subsurface flow constructed wetlands.In this study,the developing process of clogging caused...The accumulation of organic matter in substratum pores is regarded as an important factor causing clogging separately in the subsurface flow constructed wetlands.In this study,the developing process of clogging caused by biofilm growth or organic particle accumulation instead of total organic matter accumulation was investigated in two groups of lab-scale vertical flow constructed wetlands（VFCWs）,which were fed with glucose（dissolved organic matter） and starch（particulate organic matter） influent.Results showed that the growth of biofilms within the substratum pores certainly caused remarkable reduction of effective porosity,especially for the strong organic wastewater,whereas its influence on infiltration rate was negligible.It was implied that the most important contribution of biofilm growth to clogging was accelerating the occurrence of clogging.In comparison with biofilm growth,particles accumulation within pores could rapidly reduce infiltration rate besides effective porosity and the clogging occurred in the upper 0-15 cm layer.With approximately equal amount of accumulated organic matter,the effective porosity of the clogged layer in starch-fed systems was far less than that of glucose-fed systems,which indicated that composition and accumulation mode in addition to the amount of the accumulated organic matter played an important role in causing clogging.展开更多
The nozzle clogging behavior of Ti-bearing IF steel was studied by metallographic analysis,scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS）,and X-ray diffraction（XRD）.According to the exper...The nozzle clogging behavior of Ti-bearing IF steel was studied by metallographic analysis,scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS）,and X-ray diffraction（XRD）.According to the experimental results,nozzle clogging primarily appears three layers.There are a lot of large-sized iron particles in the inner layer and mainly slag phase in the middle and outer layers.The principal clog constituents of the inner layer are loose alumina cluster inclusions and granular shaped alumina inclusions,containing iron particles. The clog constituents of the middle layer are mainly dendrite alumina inclusions.The primary phases existing in nozzle clogging are FeO·TiO2 and FeO·Al2O3 besidesα-Al2O3 and a-Fe.The FeO·TiO2 phases among the deposits adhere the deposits together firmly enough to lead to the inferior castability of Ti-bearing ultra low carbon steel compared with that of Ti-free low carbon Al-killed steel.展开更多
Chlorination has been recognized as an efficient and economically favorable method for treating clogging in drip emitters caused by biological growth during sewage application. Further important criteria for determini...Chlorination has been recognized as an efficient and economically favorable method for treating clogging in drip emitters caused by biological growth during sewage application. Further important criteria for determining an optimal chlorination scheme are the different responses of crops to the chloride added into the soil through chlorination. During two seasons in 2008 and 2009, field experiments were conducted in a solar-heated greenhouse with drip irrigation systems applying secondary sewage effluent to tomato plants to investigate the influences of chlorine injection intervals and levels on plant growth, yield, fruit quality, and emitter clogging. Injection intervals ranging from 2 to 8 wk and injection concentrations ranging 2-50 mg L-1 of free chlorine residual at the end of the laterals were used. For the 2008 experiments, the yield from the treatments of sewage application with chlorination was 7.5% lower than the yield from the treatment of sewage application without chlorination, while the yields for the treatments with and without chlorination were similar for the 2009 experiments. The statistical tests indicated that neither the chlorine injection intervals and concentrations nor the interactions between the two significantly influenced plant height, leaf area, or tomato yield for both years. The qualities of the fruit in response to chlorination were parameter-dependent. Chlorination did not significantly influence the quality of ascorbic acid, soluble sugar, or soluble acids, but the interaction between the chlorine injection interval and the chlorine concentration significantly influenced the levels of soluble solids. It was also confirmed that chlorination was an effective method for reducing biological clogging. These results suggested that chlorination is safe for a crop that has a moderate sensitivity to chlorine, like tomato, and can maintain a high level of performance in drip irrigation systems applying sewage effluent.展开更多
Shield tunneling is easily obstructed by clogging in clayey strata with small soil particles.However,soil clogging rarely occurs in strata with coarse-grained soils.Theoretically,a critical particle size of soils shou...Shield tunneling is easily obstructed by clogging in clayey strata with small soil particles.However,soil clogging rarely occurs in strata with coarse-grained soils.Theoretically,a critical particle size of soils should exist,below which there is a high risk of soil clogging in shield tunneling.To determine the critical particle size,a series of laboratory tests was carried out with a large-scale rotary shear apparatus to measure the tangential adhesion strength of soils with different particle sizes and water contents.It was found that the tangential adhesion strength at the soilesteel interface gradually increased linearly with applied normal pressure.When the particle size of the soil specimen was less than 0.15 mm,the interfacial adhesion force first increased and then decreased as the water content gradually increased;otherwise,the soil specimens did not manifest any interfacial adhesion force.The amount of soil mass adhering to the steel disc was positively correlated with the interfacial adhesion force,thus the interfacial adhesion force was adopted to characterize the soil clogging risk in shield tunneling.The critical particle size of soils causing clogging was determined to be 0.15 mm.Finally,the generation mechanism of interfacial adhesion force was explored for soils with different particle sizes to explain the critical particle size of soil with clogging risk in shield tunneling.展开更多
Characterizing the permeability variation in fractured rocks is important in various subsurface applications,but how the permeability evolves in the foundation rocks of high dams during operation remains poorly unders...Characterizing the permeability variation in fractured rocks is important in various subsurface applications,but how the permeability evolves in the foundation rocks of high dams during operation remains poorly understood.This permeability change is commonly evidenced by a continuous decrease in the amount of discharge(especially for dams on sediment-laden rivers),and can be attributed to fracture clogging and/or hydromechanical coupling.In this study,the permeability evolution of fractured rocks at a high arch dam foundation during operationwas evaluated by inverse modeling based on the field timeseries data of both pore pressure and discharge.A procedure combining orthogonal design,transient flow modeling,artificial neural network,and genetic algorithm was adopted to efficiently estimate the hydraulic conductivity values in each annual cycle after initial reservoir filling.The inverse results show that the permeability of the dam foundation rocks follows an exponential decay annually during operation(i.e.K/K0=0.97e^(-0.59t)+0.03),with good agreement between field observations and numerical simulations.The significance of the obtained permeability decay function was manifested by an assessment of the long-term seepage control performance and groundwater flow behaviors at the dam site.The proposed formula is also of merit for characterizing the permeability change in riverbed rocks induced by sediment transport and deposition.展开更多
In continuous casting,the argon blowing at the tundish upper nozzle is usually used to prevent nozzle clogging,whose effect is closely related to the migration of argon bubbles and the flow behavior of the liquid stee...In continuous casting,the argon blowing at the tundish upper nozzle is usually used to prevent nozzle clogging,whose effect is closely related to the migration of argon bubbles and the flow behavior of the liquid steel in the nozzle.Here,to investigate the effects of argon blowing at the tundish upper nozzle on multiphase flow behavior in nozzle,a threedimensional model of the tundish–nozzle–mold was established for numerical simulation.The results indicate that the argon bubbles injected from the inner wall of the tundish upper nozzle first move downward along the nozzle wall under the action of the liquid steel.As the distance from the tundish upper nozzle increases,the argon bubbles gradually diffuse to the center of the nozzle.Compared with no argon blowing,the liquid steel velocity increases in the center of the nozzle and decreases near the wall with argon blowing.With increasing the argon flow rate,the concentration of bubbles in the nozzle increases,and the process of bubble group diffusion to the center region of the nozzle speeds up.This in turn increases the liquid steel velocity at the center of the nozzle but reduces near the wall.With increasing the casting speed,the concentration of bubbles in the nozzle decreases,the length of the bubble group near the nozzle wall is extended,and the liquid steel velocity at the center region and near-wall region of the nozzle increases.The mechanism of argon blowing at the tundish upper nozzle to prevent nozzle clogging is mainly realized by the isolation effect of the argon bubble group on the inner wall of the nozzle.展开更多
The type of inclusions in tundish steel and the formation mechanism of the submerged entry nozzle(SEN)clogging in the continuous casting of the rare earth(RE)high strength steel without calcium treatment were studied ...The type of inclusions in tundish steel and the formation mechanism of the submerged entry nozzle(SEN)clogging in the continuous casting of the rare earth(RE)high strength steel without calcium treatment were studied based on the plant trials and thermodynamic calculation.It was found that Ce_(2)O_(3) and CeAlO_(3) in tundish molten steel were transformed into Ce_(2)O_(2)S+CaO-Al_(2)O_(3) with the size of 2-3 lm during cooling.When the flow velocity of molten steel on surface of the SEN was slow due to the boundary layer effect,Ce_(2)O_(3) inclusion in molten steel reacted with Al_(2)O_(3) in the SEN refractory to form CeAlO3.With the continuous erosion of molten steel and reaction,the compositions of CeAlO_(3),Al_(2)O_(3) and CaO were aggregated,and the clogging layers with different zones were formed on surface of the SEN.Meanwhile,a small amount of molten steel remaining in the arc zone and corner zone of the SEN formed solidified steel.When calcium treatment is canceled,the reaction probability between inclusions in molten steel and refractory should be reduced by improving the material and shape of the SEN.展开更多
Using reclaimed wastewater for crop irrigation is a practical alternative to discharge wastewater treatment plant effluents into surface waters.However,biofouling has been identified as a major contributor to emitter ...Using reclaimed wastewater for crop irrigation is a practical alternative to discharge wastewater treatment plant effluents into surface waters.However,biofouling has been identified as a major contributor to emitter clogging in drip irrigation systems distributing reclaimed wastewater.Little is known about the biofilm structure and its influence on clogging in the drip emitter flow path.This study was first to investigate the microbial characteristics of mature biofilms present in the emitters and the effect of flow path structures on the biofilm microbial communities.The analysis of biofilm matrix structure using a scanning electron microscopy（SEM） revealed that particles in the matrix of the biofilm coupled extracellular polysaccharides（EPS） and formed sediment in the emitter flow path.Analysis of biofilm mass including protein,polysaccharide,and phospholipid fatty acids（PLFAs） showed that emitter flow path style influenced biofilm community structure and diversity.The correlations of biofilm biomass and discharge reduction after 360 h irrigation were computed and suggest that PFLAs provide the best correlation coeffcient.Comparatively,the emitter with the unsymmetrical dentate structure and shorter flow path（Emitter C） had the best anti-clogging capability.By optimizing the dentate structure,the internal flow pattern within the flow path could be enhanced as an important method to control the biofilm within emitter flow path.This study established electron microscope techniques and biochemical microbial analysis methods that may provide a framework for future emitter biofilm studies.展开更多
The influence of submerged entry nozzle clogging on the behavior of molten steel in continuously cast slab molds was studied using commercial code CFX4.3. The results indicate that clogging at the top part of the nozz...The influence of submerged entry nozzle clogging on the behavior of molten steel in continuously cast slab molds was studied using commercial code CFX4.3. The results indicate that clogging at the top part of the nozzle port not only increases the velocity of molten steel, but also enhances the wall shear stress, F number and heat flux. This clogging has the greatest effect on the behavior of molten steel. However, clogging at the top 1/3 of the nozzle only increases the velocity of molten steel and has little influence. Clogging at the bottom of the nozzle almost has no influence.展开更多
A nozzle clogging online forecasting model based on hydrodynamics engineering was developed, in which the actual flow rate was calculated from the mold width, thickness, and casting speed. There is a linear relationsh...A nozzle clogging online forecasting model based on hydrodynamics engineering was developed, in which the actual flow rate was calculated from the mold width, thickness, and casting speed. There is a linear relationship between the theoretical flow rate and the slide gate opening ratio as the molten steel level, argon flow rate, and the top slag weight are kept constant, and the relationship can be obtained by regression of the data collected at the beginning of the first heat in each casting sequence when the nozzle clogging does not occur. Then, during the casting, the theoretical flow rate can be calculated at intervals of one second. Comparing the theoretical flow rate with the actual flow rate, the online nozzle clogging ratio can be obtained at intervals of one second. The computer model based on the conception of the nozzle clogging ratio can display the degree of the nozzle clogging intuitively.展开更多
Tailoring water supply to achieve confined heating has proven to be an effective strategy for boosting solar interfacial evaporation rates.However,because of salt clogging during desalination,a critical point of const...Tailoring water supply to achieve confined heating has proven to be an effective strategy for boosting solar interfacial evaporation rates.However,because of salt clogging during desalination,a critical point of constriction occurs when controlling the water rate for confined heating.In this study,we demonstrate a facile and scalable weaving technique for fabricating core-sheath photothermal yarns that facilitate controlled water supply for stable and efficient interracial solar desalination.The core-sheath yarn comprises modal fibers as the core and carbon fibers as the sheaths.Because of the core-sheath design,remarkable liquid pumping can be enabled in the carbon fiber bundle of the dispersed superhydrophilic modal fibers.Our woven fabrics absorb a high proportion(92%)of the electromagnetic radiation in the solar spectrum because of the weaving structure and the carbon fiber sheath.Under one-sun(1 kW·m^(-2))illumination,our woven fabric device can achieve the highest evaporation rate(of 2.12kg·m^(-2)·h^(-1) with energy conversion efficiency:93.7%)by regulating the number of core-sheath yarns.Practical application tests demonstrate that our device can maintain high and stable desalination performance in a 5 wt%NaCl solution.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(No.FRF-BD-23-01).
文摘Non-metallic inclusions in steel are a significant challenge,affecting material properties and leading to issues such as stress concentration,cracking,and accelerated corrosion.Current methods for removing inclusions,including bubble,electromagnetic stirring,filtration separation,fluid flow,and sedimentation,often struggle with the removal of fine inclusions.Apart from these known methods,pulsed electric current(PEC),as an emerging technology,has demonstrated immense potential and environmental advantages.PEC offers adjustable current parameters and simple equipment,making it an attractive alternative to traditional methods.Its green energy-saving features and excellent results in regulating inclusion morphology and migration,as well as inhibiting submerged entry nozzle(SEN)clogging,make it a promising technology.In comparison to continuous current technology,PEC has shown significant advantages in regulating inclusions,not only improving purification efficiency but also demonstrating outstanding performance in flow stability and energy consumption.The ability of PEC to efficiently reduce inclusion numbers enhances the purity and quality of molten steel,improving its mechanical properties.Currently,the theoretical basis for controlling the movement of inclusions by current is mainly composed of three major theories:the double electric layer theory,electromagnetic force reverse separation theory,and electric free energy drive theory.These theories together form an important framework for researchers to understand and optimize the behavior of impurity movement controlled by electric current.Looking ahead,PEC is expected to pave the way for new solutions in directional regulation of inclusion migration,efficient inclusion removal,SEN clogging prevention,and the purification of molten steel.
文摘Colloidal transport and deposition in porous media are complex processes that result from the interaction between hydrodynamics(velocity,pore geometry,etc.)and Derjaguin-Landau-Verwey-Overbeek(DLVO)forces(particle-particle and particle-surface).They have important implications for engineering applications involving the reinjection of a fluidinto a medium,such as geothermal energy.The investigation of permeability stability is critical to ensure the sustainability of activities.This work aims to study the clogging mechanisms in a rock-like porous medium using a microfluidicdevice.The pore-throat network distributions reveal that the micromodel geometry mimics real rock samples.The transport of a monodispersed suspension is studied at different concentrations.Image analysis,velocity fieldmodeling,and pressure drop measurement are used to assess preferential clogging sites and porous medium permeability reduction,respectively.Experiments have shown that retention sites are located around preferential flow paths with relatively high flow velocities.When clogged,the pore thresholds are the deposition zones that lead to a reduction in permeability.However,pore bodies may also constitute deposition zones.Interestingly,as the concentration of the suspension increases,the kinetics of the permeability reduction are delayed,and the clogging mechanisms,as well as the type of deposit,evolve.Finally,at very high concentrations,the effects of hydrodynamic stripping are more important.These observations emphasize the role of the porous medium geometry in colloidal transport and deposition and thus permeability reduction.
基金supported by the National Natural Science Foundation of China(Grant Nos.12365007 and 12265017)Yunnan Fundamental Research Projects(Grant Nos.202101AS070018 and 202101AV070015)+1 种基金the Scientific Research Foundation of the Yunnan Provincial Department of Education(Grant No.2023J1208)Xingdian Talents Support Program,and Yunnan Province Ten Thousand Talents Plan Young&Elite Talents Project,and Yunnan Province Computational Physics and Applied Science and Technology Innovation Team.The numerical simulation and significance estimation were performed on the Key Laboratory of High-Density Computing,Zhaotong University。
文摘Particle transport is a fundamental aspect of various systems,from artificial to biological.A common assumption is that particle motion follows Markovian(memoryless)processes in the absence of interaction between particles.However,hydrodynamic memory and the interaction between particles are ubiquitous,leaving many fundamental questions unanswered regarding transport of interacting particles involving hydrodynamic drag in corrugated channels,as described by the fractional Langevin equation.This study examines the hydrodynamic transport of interacting non-Brownian particles moving within a corrugated channel.We propose a method that relies on factors such as temperature,the driving force to alternate between no transport and finite net transport.Of importance is to note that the absence of transport results from the clogging,while the transport consists of collective motion and independent motion.The transport systems investigated in this work suggest the potential for sensor functionality within the system.Our findings may prove valuable for exploring the transport with hydrodynamic memory in various fields,including biology,physics,and chemistry.
基金National Natural Science Foundation of China(Nos.U21A20116,U21A20117 and 52304347)National Natural Science Foundation of Liaoning(Nos.2023-MSBA-135 and 2023-BSBA-107)+1 种基金the Fundamental Research Funds for the Central Universities(Nos.N2409006 and N2409008)are acknowledged to support this workSwedish Foundation for International Cooperation in Research and Higher Education(STINT,Project No.IB2022-9228)is acknowledged by W.Mu to support his visit between KTH(Sweden)and NEU(China).
文摘Understanding the motion behaviors of non-metallic inclusions in the liquid metal is important for clean steel production.High-temperature confocal laser scanning microscopy is applied to investigate the effect of different Ti and Al contents on the agglomeration behavior of non-metallic inclusions in low carbon steels.Furthermore,the agglomeration mechanism of inclusions was investigated through quantitative analysis of in-situ observation experiments and a modified Kralchevsky-Paunov model.The obtained results indicate that Al_(2)O_(3)is the main type inclusion in the low-alloys steels with both Al and Ti addition.This type of inclusion is more likely to absorb surrounding small-size inclusion particles,leading to a further growth for the cluster formation and contributing to a serious engineering problem,nozzle clogging.Besides,TiO_(x)is the main type inclusion in the molten steel with only Ti addition,and this type of inclusion is less likely to agglomerate and the individual inclusion particles show a‘free’motion with the fluid of molten steel.The difference between these two types of inclusions is due to the difference in attractive force and action distance at the meniscus created by the inclusion/steel/Ar multiple interfaces and influenced by the physical parameters,e.g.,contact angle and interface energy between inclusion and steel,and surface tension of the melt.
基金Supported by National Natural Science Foundation of China(Grant Nos.52205481,52305477)Outstanding Youth Innovation Team in Universities of Shandong Province(Grant No.2023KJ114)+2 种基金Qingdao Science and Technology Planning Park Cultivation Plan(Grant No.23-1-5-yqpy-17-qy)Young Talent of Lifting engineering for Science and Technology in Shandong(Grant No.SDAST2024QTA043)Key Lab of Industrial Fluid Energy Conservation and Pollution Control(Ministry of Education)(Grant No.CK-2024-0033)。
文摘Microgrinding is widely used in clinical bone surgery,but saline spray cooling faces technical challenges such as low wettability at the microgrinding tool–bone interface,easy clogging of the microgrinding tools,and high grinding temperatures.These issues can lead to bone necrosis,irreversible thermal damage to nerves,or even surgical failure.Inspired by the water-trapping and directional transportation abilities of desert beetles,this study proposes a biomimetic desert beetle microgrinding tool.The flow-field distribution directly influences the convective heat transfer of the cooling medium in the grinding zone,which in turn affects the grinding temperature.To address this,a mathematical model of the two-phase flow field at the biomimetic microgrinding tool–bone interface is developed.The results indicate an average error of 14.74%between the calculated and experimentally obtained airflow field velocities.Next,a biomimetic desert beetle microgrinding tool is prepared.Experiments with physiological saline spray cooling were conducted on fresh bovine femur bone,which has mechanical properties similar to human bone.Results show that,compared with conventional microgrinding tools,the biomimetic tools reduced bone surface temperature by 21.7%,13.2%,5.8%,20.3%,and 25.8%at particle sizes of 150#,200#,240#,270#,and 300#,respectively.The surface morphology of the biomimetic microgrinding tools after grinding is observed and analyzed,revealing a maximum clogging area reduction of 23.0%,which is 6.1%,6.0%,10.0%,15.6%,and 9.5%less than that observed with conventional tools.Finally,this study unveils the dynamic mechanism of cooling medium transfer in the flow field at the biomimetic microgrinding tool–bone interface.This research provides theoretical guidance and technical support for clinical bone resection surgery.
基金supported by Sultan Qaboos University through grants EG/DVC/WRC/21/01,and DR/RG/17.
文摘Managed Aquifer Recharge(MAR)is a strategic approach to artificially replenishing groundwater supplies and has become an integral component of global water resource management.The number of MAR projects has steadily increased in recent decades,yet many have failed to achieved their intended outcomes,underscoring the complexity of project implementation.This review is dedicated to examine existing research and reports on MAR performance and impacts,aiming to establish objective criteria for gauging the success and identify key factors influencing the effectiveness of MAR project.Five critical performance factors have been identified as major determinants of MAR performance:aquifer transmissivity,vertical permeability,availability of recharge water,recharge water quality,and aquifer thickness,geometry and boundary conditions.These factors are directly related to project success and significantly shape MAR outcomes.In addition,this review explores research-based strategies to improve MAR success,including cutting-edge methodologies,technological innovations,and integrated management approaches to address key challenges.The ultimate goal is to foster more efficient,effective,and sustainable MAR practices,thereby enhancing the resilience and sustainability of water resource management.
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.2023YJS053)the National Natural Science Foundation of China(Grant No.52278386).
文摘To fundamentally alleviate the excavation chamber clogging during slurry tunnel boring machine(TBM)advancing in hard rock,large-diameter short screw conveyor was adopted to slurry TBM of Qingdao Jiaozhou Bay Second Undersea Tunnel.To evaluate the discharging performance of short screw conveyor in different cases,the full-scale transient slurry-rock two-phase model for a short screw conveyor actively discharging rocks was established using computational fluid dynamics-discrete element method(CFD-DEM)coupling approach.In the fluid domain of coupling model,the sliding mesh technology was utilized to describe the rotations of the atmospheric composite cutterhead and the short screw conveyor.In the particle domain of coupling model,the dynamic particle factories were established to produce rock particles with the rotation of the cutterhead.And the accuracy and reliability of the CFD-DEM simulation results were validated via the field test and model test.Furthermore,a comprehensive parameter analysis was conducted to examine the effects of TBM operating parameters,the geometric design of screw conveyor and the size of rocks on the discharging performance of short screw conveyor.Accordingly,a reasonable rotational speed of screw conveyor was suggested and applied to Jiaozhou Bay Second Undersea Tunnel project.The findings in this paper could provide valuable references for addressing the excavation chamber clogging during ultra-large-diameter slurry TBM tunneling in hard rock for similar future.
基金Supported by National Natural Science Foundation of China(41071214)~~
文摘[Objective] The aim was to al eviate the constructed wetland clogging problems and to explore to the effects of hydraulic loading on wetland clogging. [Method] The experiment, through artificial soil columns, simulated vertical flow arti-ficial wetland, set four hydraulic load level at 50, 100, 150 and 200 cm/d, to identify the impact of hydraulic loading on wetland clogging and to explore the factors run-ning threshold. [Result] The results show that the different levels of hydraulic loading have greater impact; in the constructed wetland clogging process under high hy-draulic loading of 200 cm/d, the effective life was only six months, and the single factor can be speculated that the threshold of the hydraulic load should be at 100-150 cm/d; system can last for six months at low hydraulic loading and last for three months at medium hydraulic load. [Conclusion] The research provides references for wetland clogging experiments in future.
基金supported by the Natural Science Foundation of Jiangsu Province (No.BK2006710)
文摘The accumulation of organic matter in substratum pores is regarded as an important factor causing clogging separately in the subsurface flow constructed wetlands.In this study,the developing process of clogging caused by biofilm growth or organic particle accumulation instead of total organic matter accumulation was investigated in two groups of lab-scale vertical flow constructed wetlands（VFCWs）,which were fed with glucose（dissolved organic matter） and starch（particulate organic matter） influent.Results showed that the growth of biofilms within the substratum pores certainly caused remarkable reduction of effective porosity,especially for the strong organic wastewater,whereas its influence on infiltration rate was negligible.It was implied that the most important contribution of biofilm growth to clogging was accelerating the occurrence of clogging.In comparison with biofilm growth,particles accumulation within pores could rapidly reduce infiltration rate besides effective porosity and the clogging occurred in the upper 0-15 cm layer.With approximately equal amount of accumulated organic matter,the effective porosity of the clogged layer in starch-fed systems was far less than that of glucose-fed systems,which indicated that composition and accumulation mode in addition to the amount of the accumulated organic matter played an important role in causing clogging.
基金supported by the National Key Technologies R&D Program of China(No.2006BAE03A06)
文摘The nozzle clogging behavior of Ti-bearing IF steel was studied by metallographic analysis,scanning electron microscopy（SEM）, energy dispersive spectroscopy（EDS）,and X-ray diffraction（XRD）.According to the experimental results,nozzle clogging primarily appears three layers.There are a lot of large-sized iron particles in the inner layer and mainly slag phase in the middle and outer layers.The principal clog constituents of the inner layer are loose alumina cluster inclusions and granular shaped alumina inclusions,containing iron particles. The clog constituents of the middle layer are mainly dendrite alumina inclusions.The primary phases existing in nozzle clogging are FeO·TiO2 and FeO·Al2O3 besidesα-Al2O3 and a-Fe.The FeO·TiO2 phases among the deposits adhere the deposits together firmly enough to lead to the inferior castability of Ti-bearing ultra low carbon steel compared with that of Ti-free low carbon Al-killed steel.
基金financially supported by the National Natural Science Foundation of China (50779078)
文摘Chlorination has been recognized as an efficient and economically favorable method for treating clogging in drip emitters caused by biological growth during sewage application. Further important criteria for determining an optimal chlorination scheme are the different responses of crops to the chloride added into the soil through chlorination. During two seasons in 2008 and 2009, field experiments were conducted in a solar-heated greenhouse with drip irrigation systems applying secondary sewage effluent to tomato plants to investigate the influences of chlorine injection intervals and levels on plant growth, yield, fruit quality, and emitter clogging. Injection intervals ranging from 2 to 8 wk and injection concentrations ranging 2-50 mg L-1 of free chlorine residual at the end of the laterals were used. For the 2008 experiments, the yield from the treatments of sewage application with chlorination was 7.5% lower than the yield from the treatment of sewage application without chlorination, while the yields for the treatments with and without chlorination were similar for the 2009 experiments. The statistical tests indicated that neither the chlorine injection intervals and concentrations nor the interactions between the two significantly influenced plant height, leaf area, or tomato yield for both years. The qualities of the fruit in response to chlorination were parameter-dependent. Chlorination did not significantly influence the quality of ascorbic acid, soluble sugar, or soluble acids, but the interaction between the chlorine injection interval and the chlorine concentration significantly influenced the levels of soluble solids. It was also confirmed that chlorination was an effective method for reducing biological clogging. These results suggested that chlorination is safe for a crop that has a moderate sensitivity to chlorine, like tomato, and can maintain a high level of performance in drip irrigation systems applying sewage effluent.
基金The financial support from the National Natural Science Foun-dation of China(Grant Nos.52022112 and 51778637)the Sci-ence and Technology Innovation Program of Hunan Province(Grant No.2021RC3015)are acknowledged and appreciated.
文摘Shield tunneling is easily obstructed by clogging in clayey strata with small soil particles.However,soil clogging rarely occurs in strata with coarse-grained soils.Theoretically,a critical particle size of soils should exist,below which there is a high risk of soil clogging in shield tunneling.To determine the critical particle size,a series of laboratory tests was carried out with a large-scale rotary shear apparatus to measure the tangential adhesion strength of soils with different particle sizes and water contents.It was found that the tangential adhesion strength at the soilesteel interface gradually increased linearly with applied normal pressure.When the particle size of the soil specimen was less than 0.15 mm,the interfacial adhesion force first increased and then decreased as the water content gradually increased;otherwise,the soil specimens did not manifest any interfacial adhesion force.The amount of soil mass adhering to the steel disc was positively correlated with the interfacial adhesion force,thus the interfacial adhesion force was adopted to characterize the soil clogging risk in shield tunneling.The critical particle size of soils causing clogging was determined to be 0.15 mm.Finally,the generation mechanism of interfacial adhesion force was explored for soils with different particle sizes to explain the critical particle size of soil with clogging risk in shield tunneling.
基金the National Key R&D Program of China(Grant No.2018YFC0407001)the National Natural Science Foundation of China(Grant No.51925906)the Research Program of China Three Gorges Corporation(Grant No.XLD/2119)are gratefully acknowledged.
文摘Characterizing the permeability variation in fractured rocks is important in various subsurface applications,but how the permeability evolves in the foundation rocks of high dams during operation remains poorly understood.This permeability change is commonly evidenced by a continuous decrease in the amount of discharge(especially for dams on sediment-laden rivers),and can be attributed to fracture clogging and/or hydromechanical coupling.In this study,the permeability evolution of fractured rocks at a high arch dam foundation during operationwas evaluated by inverse modeling based on the field timeseries data of both pore pressure and discharge.A procedure combining orthogonal design,transient flow modeling,artificial neural network,and genetic algorithm was adopted to efficiently estimate the hydraulic conductivity values in each annual cycle after initial reservoir filling.The inverse results show that the permeability of the dam foundation rocks follows an exponential decay annually during operation(i.e.K/K0=0.97e^(-0.59t)+0.03),with good agreement between field observations and numerical simulations.The significance of the obtained permeability decay function was manifested by an assessment of the long-term seepage control performance and groundwater flow behaviors at the dam site.The proposed formula is also of merit for characterizing the permeability change in riverbed rocks induced by sediment transport and deposition.
基金the National Natural Science Foundation of China(Nos.51874215 and 51974213).
文摘In continuous casting,the argon blowing at the tundish upper nozzle is usually used to prevent nozzle clogging,whose effect is closely related to the migration of argon bubbles and the flow behavior of the liquid steel in the nozzle.Here,to investigate the effects of argon blowing at the tundish upper nozzle on multiphase flow behavior in nozzle,a threedimensional model of the tundish–nozzle–mold was established for numerical simulation.The results indicate that the argon bubbles injected from the inner wall of the tundish upper nozzle first move downward along the nozzle wall under the action of the liquid steel.As the distance from the tundish upper nozzle increases,the argon bubbles gradually diffuse to the center of the nozzle.Compared with no argon blowing,the liquid steel velocity increases in the center of the nozzle and decreases near the wall with argon blowing.With increasing the argon flow rate,the concentration of bubbles in the nozzle increases,and the process of bubble group diffusion to the center region of the nozzle speeds up.This in turn increases the liquid steel velocity at the center of the nozzle but reduces near the wall.With increasing the casting speed,the concentration of bubbles in the nozzle decreases,the length of the bubble group near the nozzle wall is extended,and the liquid steel velocity at the center region and near-wall region of the nozzle increases.The mechanism of argon blowing at the tundish upper nozzle to prevent nozzle clogging is mainly realized by the isolation effect of the argon bubble group on the inner wall of the nozzle.
基金the financial support of the Natural Science Foundation of Inner Mongolia Autonomous Region of China(No.2020MS0517)Science and Technology Project of Inner Mongolia Autonomous Region of China(No.2020GG0109).
文摘The type of inclusions in tundish steel and the formation mechanism of the submerged entry nozzle(SEN)clogging in the continuous casting of the rare earth(RE)high strength steel without calcium treatment were studied based on the plant trials and thermodynamic calculation.It was found that Ce_(2)O_(3) and CeAlO_(3) in tundish molten steel were transformed into Ce_(2)O_(2)S+CaO-Al_(2)O_(3) with the size of 2-3 lm during cooling.When the flow velocity of molten steel on surface of the SEN was slow due to the boundary layer effect,Ce_(2)O_(3) inclusion in molten steel reacted with Al_(2)O_(3) in the SEN refractory to form CeAlO3.With the continuous erosion of molten steel and reaction,the compositions of CeAlO_(3),Al_(2)O_(3) and CaO were aggregated,and the clogging layers with different zones were formed on surface of the SEN.Meanwhile,a small amount of molten steel remaining in the arc zone and corner zone of the SEN formed solidified steel.When calcium treatment is canceled,the reaction probability between inclusions in molten steel and refractory should be reduced by improving the material and shape of the SEN.
基金supported by the National Natural Science Foundation of China (No.50379053,50609029,50779068)
文摘Using reclaimed wastewater for crop irrigation is a practical alternative to discharge wastewater treatment plant effluents into surface waters.However,biofouling has been identified as a major contributor to emitter clogging in drip irrigation systems distributing reclaimed wastewater.Little is known about the biofilm structure and its influence on clogging in the drip emitter flow path.This study was first to investigate the microbial characteristics of mature biofilms present in the emitters and the effect of flow path structures on the biofilm microbial communities.The analysis of biofilm matrix structure using a scanning electron microscopy（SEM） revealed that particles in the matrix of the biofilm coupled extracellular polysaccharides（EPS） and formed sediment in the emitter flow path.Analysis of biofilm mass including protein,polysaccharide,and phospholipid fatty acids（PLFAs） showed that emitter flow path style influenced biofilm community structure and diversity.The correlations of biofilm biomass and discharge reduction after 360 h irrigation were computed and suggest that PFLAs provide the best correlation coeffcient.Comparatively,the emitter with the unsymmetrical dentate structure and shorter flow path（Emitter C） had the best anti-clogging capability.By optimizing the dentate structure,the internal flow pattern within the flow path could be enhanced as an important method to control the biofilm within emitter flow path.This study established electron microscope techniques and biochemical microbial analysis methods that may provide a framework for future emitter biofilm studies.
文摘The influence of submerged entry nozzle clogging on the behavior of molten steel in continuously cast slab molds was studied using commercial code CFX4.3. The results indicate that clogging at the top part of the nozzle port not only increases the velocity of molten steel, but also enhances the wall shear stress, F number and heat flux. This clogging has the greatest effect on the behavior of molten steel. However, clogging at the top 1/3 of the nozzle only increases the velocity of molten steel and has little influence. Clogging at the bottom of the nozzle almost has no influence.
基金financially supported by the State EconomicTrade Commission of China (No.OIBK-098-02-07)
文摘A nozzle clogging online forecasting model based on hydrodynamics engineering was developed, in which the actual flow rate was calculated from the mold width, thickness, and casting speed. There is a linear relationship between the theoretical flow rate and the slide gate opening ratio as the molten steel level, argon flow rate, and the top slag weight are kept constant, and the relationship can be obtained by regression of the data collected at the beginning of the first heat in each casting sequence when the nozzle clogging does not occur. Then, during the casting, the theoretical flow rate can be calculated at intervals of one second. Comparing the theoretical flow rate with the actual flow rate, the online nozzle clogging ratio can be obtained at intervals of one second. The computer model based on the conception of the nozzle clogging ratio can display the degree of the nozzle clogging intuitively.
基金financial support from the National Natural Science Foundation of China(52103064 and U21A2095)the Key Research and Development Program of Hubei Province(2021BAA068)National Local Joint Laboratory for Advanced Textile Processing and Clean Production(FX2022001)。
文摘Tailoring water supply to achieve confined heating has proven to be an effective strategy for boosting solar interfacial evaporation rates.However,because of salt clogging during desalination,a critical point of constriction occurs when controlling the water rate for confined heating.In this study,we demonstrate a facile and scalable weaving technique for fabricating core-sheath photothermal yarns that facilitate controlled water supply for stable and efficient interracial solar desalination.The core-sheath yarn comprises modal fibers as the core and carbon fibers as the sheaths.Because of the core-sheath design,remarkable liquid pumping can be enabled in the carbon fiber bundle of the dispersed superhydrophilic modal fibers.Our woven fabrics absorb a high proportion(92%)of the electromagnetic radiation in the solar spectrum because of the weaving structure and the carbon fiber sheath.Under one-sun(1 kW·m^(-2))illumination,our woven fabric device can achieve the highest evaporation rate(of 2.12kg·m^(-2)·h^(-1) with energy conversion efficiency:93.7%)by regulating the number of core-sheath yarns.Practical application tests demonstrate that our device can maintain high and stable desalination performance in a 5 wt%NaCl solution.
