The circadian system of mammals is composed of a hierarchical network of oscillators,including a core clock and peripheral clocks.The core clock receives an external photic signal and transmits it to the peripheral cl...The circadian system of mammals is composed of a hierarchical network of oscillators,including a core clock and peripheral clocks.The core clock receives an external photic signal and transmits it to the peripheral clocks,which,in turn,feed back to the core clock.Aging affects various functions of organisms including the circadian system.Entrainment displays the adaptability of the circadian system to changes in the external environment.However,there is currently no systematic study on the effects of aging on the entrainment capability.To explore the influencing mechanism,we develop a mathematical model of two populations of Goodwin oscillators,which represent the core clock and peripheral clocks.Based on numerical simulations,we conduct a detailed study on the impact of three aging-related factors on the entrainment capability represented by the entrainment range,entrainment time,and entrainment phase.The results indicate that the decrease in the sensitivity of suprachiasmatic nucleus(SCN)to light and the coupling strength from the SCN to the peripheral clocks due to aging increase the phase difference between the core and peripheral clocks,narrow the entrainment range,and prolong the entrainment time.A reduction in the coupling strength within the SCN has little effect on the three aspects mentioned above but increases the entrainment phase.Overall,aging reduces the circadian system's adaptability to the external environment,and the increased entrainment phase may lead to corresponding sleep problems.We also show that modulating the internal coupling strength in the peripheral clocks can mitigate aging effects;this provides an idea for using peripheral clocks to adjust the core clock,while also revealing new insights into the interaction between aging and the elasticity of the circadian system.This mechanism provides theoretical support for treating or alleviating circadian system disorders or sleep problems caused by aging.展开更多
In froth flotation,overall recovery of the floatable particles consists of true recovery and recovery by entrainment,where entrainment refers to the non-selective recovery of particles in the concentrate.To understand...In froth flotation,overall recovery of the floatable particles consists of true recovery and recovery by entrainment,where entrainment refers to the non-selective recovery of particles in the concentrate.To understand and optimize the flotation process with regard to process conditions,it is essential to distinguish true flotation recovery from overall recovery.The established methods rely on tailored flotation experiments,unrealistic flotation conditions,or using external tracers which can be different in density and crystal structure to the mineral(s) of interest.This study presents an approach to utilize naturally occuring suitable tracers to estimate the entrainment component from overall recovery of individual particles by establishing a relationship between their settling velocity coefficient and recovery probability.Recovery probabilities of individual particles are computed using particle-based separation modelling.The approach is demonstrated for a copper ore,where naturally occurring rutile was used as the tracer to determine the entrained component of the overall recovery of chalcopyrite particles.Laboratory flotation experiments revealed that entrainment accounted for up to 6% of the overall recovery probability of fully liberated chalcopyrite particles in the fine size fractions.This approach provides a practical method for entrainment correction enabling a more accurate evaluation of true flotation recovery.展开更多
Background: Brainwave entrainment using binaural beats has shown potential in treating tinnitus, but most studies have focused on one-month treatment durations. Objective: This study aimed to evaluate the time-bound e...Background: Brainwave entrainment using binaural beats has shown potential in treating tinnitus, but most studies have focused on one-month treatment durations. Objective: This study aimed to evaluate the time-bound efficacy of brainwave entrainment using binaural beats, comparing it to a standard tinnitus masker over a three-month duration. Method: Sixty-three individuals having tinnitus with normal hearing sensitivity were enrolled in the study. The participants were categorized into groups Ⅰ, Ⅱ, and Ⅲ. They were provided with delta(4 Hz) and alpha(10 Hz) frequency binaural beats and standard tinnitus masker, respectively, for a duration of three months. The tinnitus handicap inventory(THI) scores, Visual analogue scale(VAS) rating for tinnitus distress, and quality of life parameters were measured. The reductions obtained for each measure during the end of the first, second and third month were measured and compared across the groups. Results: All three groups showed considerable reductions in THI and VAS scores and improvements in the quality of life domains, focusing on physical and psychological health. However, groups Ⅰ and Ⅱ, who received binaural beats stimuli, showed higher benefits than those who received standard tinnitus masker. Conclusion: The results of the current study indicated that binaural beats can be an effective treatment technique for individuals with tinnitus having normal hearing sensitivity. Clinicians and otology/audiology practitioners shall adopt this innovative treatment after further validating these findings.展开更多
Soot is a flocculent carbon nanoparticle that results the imperfect combustion of fossil fuel,and numerous studies are dedicated to the reduction of soot production to alleviate the associated environmental problems.H...Soot is a flocculent carbon nanoparticle that results the imperfect combustion of fossil fuel,and numerous studies are dedicated to the reduction of soot production to alleviate the associated environmental problems.However,soot as a functional material is also widely used in energy storage and superhydrophobic materials.As a partial oxidation technology,the entrained flow coal gasification process will produce part of the soot.It is important to separate soot from the coal gasification fine slag(CGFS)and understand its structural characteristics for soot utilization.For this purpose,two industrial typical pulverized coal gasification fine slag(PCGFS)and coal-water slurry gasification fine slag(WCGFS)were selected for this study.The results showed that both fine slags were rich in soot,and the dry ash free mass fraction of soot in PCGFS and WCGFS was 6.24%and 2.91%,respectively,and the soot of PCGFS had a hollow carbon nanosphere morphology,while the soot of WCGFS showed a flocculent irregular morphology.The average fringe length,fringe tortuosity,and fringe spacing of the soot were 0.84 nm,1.21,and 0.45 nm,respectively.Compared to the WCGFS,the soot particles of PCGFS have less continuity of molecular bonds within the lattice,the larger the defects within the lattice,the fewer isolated lattice carbon layers there are.This study provides important theoretical support for understanding the structural characteristics and next applications of soot in the entrained flow coal gasification fine slag.展开更多
This study investigates the air–water interaction dynamics in jet streams,with particular emphasis on the transition from the cavity to the far-field regions.A dual-tip conductivity phase-detection probe was employed...This study investigates the air–water interaction dynamics in jet streams,with particular emphasis on the transition from the cavity to the far-field regions.A dual-tip conductivity phase-detection probe was employed to analyze four distinct downstream water levels.Based on the development of the cross-sectional mean air concentration,the jet flow was divided into four distinct regions:the jet length region,impact region,splash region,and far-field region.The results demonstrate varying trends in the evolution of the mean air concentration and maximum bubble frequency.Downstream water levels exerted a significant influence on these parameters in the splash and far-field regions,whereas minimal variation was observed in the impact region.Additionally,notable differences were identified in the probability density function of water droplets between the cavity and downstream regions.Furthermore,downstream water depth was found to have a negligible effect on the proportion of small-sized droplets in both the impact and splash regions.展开更多
The process of entrainment-mixing between cumulus clouds and the ambient air is important for the development of cumulus clouds.Accurately obtaining the entrainment rate(λ)is particularly important for its parameteri...The process of entrainment-mixing between cumulus clouds and the ambient air is important for the development of cumulus clouds.Accurately obtaining the entrainment rate(λ)is particularly important for its parameterization within the overall cumulus parameterization scheme.In this study,an improved bulk-plume method is proposed by solving the equations of two conserved variables simultaneously to calculateλof cumulus clouds in a large-eddy simulation.The results demonstrate that the improved bulk-plume method is more reliable than the traditional bulk-plume method,becauseλ,as calculated from the improved method,falls within the range ofλvalues obtained from the traditional method using different conserved variables.The probability density functions ofλfor all data,different times,and different heights can be well-fitted by a log-normal distribution,which supports the assumed stochastic entrainment process in previous studies.Further analysis demonstrate that the relationship betweenλand the vertical velocity is better than other thermodynamic/dynamical properties;thus,the vertical velocity is recommended as the primary influencing factor for the parameterization ofλin the future.The results of this study enhance the theoretical understanding ofλand its influencing factors and shed new light on the development ofλparameterization.展开更多
Following the parameterization of sheared entrainment obtained in the companion paper, Liu et al. （2016）, the present study aims to further investigate the characteristics of entrainment, and develop a simple model ...Following the parameterization of sheared entrainment obtained in the companion paper, Liu et al. （2016）, the present study aims to further investigate the characteristics of entrainment, and develop a simple model for predicting the growth rate of a well-developed and sheared CBL. The relative stratification, defined as the ratio of the stratification in the free atmosphere to that in the entrainment zone, is found to be a function of entrainment flux ratio （Ae）. This leads to a simple expression of the entrainment rate, in which Ae needs to be parameterized. According to the results in Liu et al. （2016）, Ae can be simply expressed as the ratio of the convective velocity scale in the sheared CBL to that in the shear-free CBL. The parameterization of the convective velocity scale in the sheared CBL is obtained by analytically solving the bulk model with several assumptions and approximations. Results indicate that the entrainment process is influenced by the dynamic effect, the interaction between mean shear and environmental stratification, and one other term that includes the Coriolis effect. These three parameterizations constitute a simple model for predicting the growth rate of a well-developed and sheared CBL. This model is validated by outputs of LESs, and the results show that it performs satisfactorily. Compared with bulk models, this model does not need to solve a set of equations for the CBL. It is more convenient to apply in numerical models.展开更多
Debris flow deposits in natural channels typically have a wide grain size distribution(GSD).The effects of bed sediment GSD on the basal entrainment rate are neglected in current debris flow erosion models.Field inves...Debris flow deposits in natural channels typically have a wide grain size distribution(GSD).The effects of bed sediment GSD on the basal entrainment rate are neglected in current debris flow erosion models.Field investigations have detected three different vertical graded bedding structures:normal,inverse,and mixed-gradation,characterized by discontinuous gradation sediment and almost without intermediate-sized particles.This study conducted small-scale flume experiments to investigate the debris flow resistance forces and entrainment characteristics by incorporating the effects of discontinuous grading bed sediments.Discontinuous graded bed sediments with varying fine particle content,volumetric water content(VWC),and roundness were designed for comparison.Debris flow resistance in erodible beds generally increased in the group with gravel of larger-sized coarse particle,lower roundness,and higher bed sediment VWC.For discontinuous grading bed sediment,the entrained depths increased in the group with gravel of smaller coarse particle sizes,larger amounts of fine particles,and higher sediment roundness,and decreased with larger VWCs.This abnormality may be attributed to the disproportionately large effects of viscous flow resistance in our small-scale flume tests.The maximum erosion rates of the continuous bed sediment were higher than those of the corresponding discontinuous bed sediment with the same maximum coarse gravel size.This is because,for discontinuous grading bed sediments,localized failure of intermediate-sized sediment grains may cause a large-scale collapse of the solid grain skeleton and enhance basal entrainment rates.A revised formula for calculating the debris flow entrainment rate is proposed by incorporating the kurtosis coefficient,which describes the distribution of discontinuous bed sediments and fine particle content.Our revised formula could facilitate an elaborate estimation of basin erosion and sediment runoff and reveal the development and recession of debris flow fans.展开更多
After the passage of a cold front, spring in northern China, the outbreak of strong wind is often accompanied by dust emissions. Through analyses of data in the atmospheric boundary layer during a typical case, it is ...After the passage of a cold front, spring in northern China, the outbreak of strong wind is often accompanied by dust emissions. Through analyses of data in the atmospheric boundary layer during a typical case, it is revealed there are rather regular gust wave packets superimposed on the basic strong wind flow. The gust-wind wave packets have a period equal to around 3 6 rains and possess coherent structure. As the vertical transport of momentum is decomposed into separate parts by （a） basic flow, （b） gust-wind, and （c） turbulence, they are all in a downwards direction at the lower levels of the atmospheric boundary layer during strong wind periods. However, （a） is the largest, while （b） and （c） are comparable. All these are very different from the case of normal weather. Besides, the friction velocity at the ground surface is also much larger than that of normal weather and should be corrected by taking the contributions of the basic flow and gust-wind into account.The strong basic flow with descending motion is very favorable for soil erosion and sand/dust emissions, but suppresses the entrainment of dust particles by keeping them within the bottom levels of the atmospheric boundary layer. Owing to the coherent structure of gust-wind, dust particles can effectively overcome the systematic descending air motion and penetrate into the middle and upper levels of the atmospheric boundary layer, and then propagate further and diffuse into the troposphere where ascending air motion prevails.展开更多
Trapped vortex combustor （TVC） is an advanced low-pollution gas turbine combustor, with the adoption of staged combustion technique. To achieve low-pollutant emission and better combustion performance, the proportio...Trapped vortex combustor （TVC） is an advanced low-pollution gas turbine combustor, with the adoption of staged combustion technique. To achieve low-pollutant emission and better combustion performance, the proportion of the air flow in each combustion zone should be precisely determined in the design of the combustor. Due to the presence of entrainment phenomenon, the total air flow in the cavity zone is difficult to estimate. To overcome the measurement difficulty, this study adopts the indirect measurement approach in the experimental research of entrainment phenomenon in the cavity. In accordance with the measurement principle, a TVC model fueled by methane is designed. Under two experimental conditions, i.e. with and without direct air intake in the cavity, the influence of the mainstream air flow velocity, the air intake velocity in the cavity, the height of inlet channel, the structure of holder and the structural proportion of the cavity on entrainment in the cavity is studied, respectively, through experiment at atmospheric temperature and pressure. The results suggest that the air flow velocity of mainstream, the air intake velocity of the cavity and the structure of the holder exert significant influence on the air entrainment, while the influence of structural proportion of the cavity is comparatively insignificant. The square root of momentum ratio of cavity air to mainstream air could be used to analyze the correlation of the entrainment data.展开更多
In this study, a water/silicone oil interface was used to simulate the steel/slag interface in a converter. A high-speed camera was used to record the entrainment process of droplets when air bubbles were passed throu...In this study, a water/silicone oil interface was used to simulate the steel/slag interface in a converter. A high-speed camera was used to record the entrainment process of droplets when air bubbles were passed through the water/silicone oil interface. Motion parameters of the bubbles and droplets were obtained using particle kinematic analysis software, and the entrainment rate of the droplets was calculated. It was found that the entrainment rate decreased from 29.5% to 0 when the viscosity of the silicone oil was increased from 60 mPa.s to 820 mPa.s in the case of bubbles with a 5 mm equivalent diameter passing through the water/silicone oil interface. The results indicate that in- creasing the viscosity of the silicone oil is conducive to reducing the entrainment rate. The entrainment rate increased from 0 to 136.3% in the case of silicone oil with a viscosity of 60 mPa.s when the equivalent diameter of the bubbles was increased from 3 mm to 7 ram. We there- fore conclude that small bubbles are also conductive to reducing the entrainment rate. The force analysis results for the water colmnn indicate that the entrainment rate of droplets is affected by the velocity of the bubble passing through the water/silicone oil interface and that the en- trainment rate decreases with the bubble velocity.展开更多
The entrainment flux ratio Ae and the inversion layer （IL） thickness are two key parameters in a mixed layer model. Ae is defined as the ratio of the entrainment heat flux at the mixed layer top to the surface heat ...The entrainment flux ratio Ae and the inversion layer （IL） thickness are two key parameters in a mixed layer model. Ae is defined as the ratio of the entrainment heat flux at the mixed layer top to the surface heat flux. The IL is the layer between the mixed layer and the free atmosphere. In this study, a parameterization of Ae is derived from the TKE budget in the first- order model for a well-developed CBL under the condition of linearly sheared geostrophic velocity with a zero value at the surface. It is also appropriate for a CBL under the condition of geostrophic velocity remaining constant with height. LESs are conducted under the above two conditions to determine the coefficients in the parameterization scheme. Results suggest that about 43% of the shear-produced TKE in the IL is available for entrainment, while the shear-produced TKE in the mixed layer and surface layer have little effect on entrainment. Based on this scheme, a new scale of convective turbulence velocity is proposed and applied to parameterize the IL thickness, The LES outputs for the CBLs under the condition of linearly sheared geostrophic velocity with a non-zero surface value are used to verify the performance of the parameterization scheme. It is found that the parameterized Ae and IL thickness agree well with the LES outputs.展开更多
Entrained flow adsorption using activated carbon as the adsorbent is widely adopted for PCDDs/Fs-abatement in municipal solid waste incineration (MSWI) process. The effects of operating parameters including flue gas t...Entrained flow adsorption using activated carbon as the adsorbent is widely adopted for PCDDs/Fs-abatement in municipal solid waste incineration (MSWI) process. The effects of operating parameters including flue gas temperature, feeding rate of activated carbon, polychlorinated dibenzodioxins and polychlorinated dibenzofurans (PCDDs/Fs) concentration at the inlet of the air pollution control device (APCD), filter materials, pressure drop on PCDDs/Fs removal efficiency are reviewed and commented upon in this paper. Evaluation on the various mechanistic models for entrained flow adsorption is carried out based on the computational simulation in terms of the actual operating condition and theoretical analysis. Finally, an advancement of en- trained flow adsorption in combination of dual bag filter is introduced.展开更多
The role of several parameters on gangue recovery in froth was investigated. Effects of frother type and collector dosage on flotation performance were tested at pH 10. The results were evaluated statistically by two-...The role of several parameters on gangue recovery in froth was investigated. Effects of frother type and collector dosage on flotation performance were tested at pH 10. The results were evaluated statistically by two-way analysis of variance without replicates, sample range and sample standard deviation. Hydrophilic mineral was recovered mainly by entrainment through hydrophobization of Ca＋2-activated quartz from tap-water in the presence of Na-oleate as collector; entrapment and slime coating were also proposed as recovery mechanisms in minority. Degree of gangue-entrainment in froth product increases by reduction in liberation size. The experimental results state that selectivity would be improved by increasing collector concentration and reducing the flotation time.展开更多
It has been noted that when the convective Richardson number Ri* is used to characterize the depth of the entrainment zone, various parameterization schemes can be obtained. This situation is often attributed to the i...It has been noted that when the convective Richardson number Ri* is used to characterize the depth of the entrainment zone, various parameterization schemes can be obtained. This situation is often attributed to the invalidity of parcel theory. However, evidence shows that the convective Richardson number Ri* might be an improper characteristic scaling parameter for the entrainment process. An attempt to use an innovative parameter to parameterize the entrainment-zone thickness has been made in this paper. Based on the examination of the data of water-tank experiments and atmospheric measurements, it is found that the total lapse rate of potential temperature across the entrainment zone is proportional to that of the capping inversion layer. Inserting this relationship into the so-called parcel theory, it thus gives a new parameterization scheme for the depth of the entrainment zone. This scheme includes the lapse rate of the capping inversion layer that plays an important role in the entrainment process. Its physical representation is reasonable. The new scheme gives a better ordering of the data measured in both water-tank and atmosphere as compared with the traditional method using Ri*. These indicate that the parcel theory can describe the entrainment process suitably and that the new parameter is better than Ri*.展开更多
The gasification kinetic modelling of two Victorian brown coal(Yallourn and Maddingley)chars and the validity for entrained flow gasification were investigated in this study.The study was conducted in a thermogravimet...The gasification kinetic modelling of two Victorian brown coal(Yallourn and Maddingley)chars and the validity for entrained flow gasification were investigated in this study.The study was conducted in a thermogravimetric analyzer(TGA)at 750–1100℃,30%–90%CO_(2)concentration using different char particle sizes within 20–106 mm.It was found that random pore model and modified volumetric model are applicable for TGA results,but volumetric model and grain model are not.The effect of particle size under106 mm on gasification rate is very limited.Activation energies of Maddingley char and Yallourn char in CO_(2)gasification are 219–220 and 197–208 k J/mol,respectively.The pre-exponential factors are in the same order of magnitude,and they increased as particle size decreased.A mathematical model was developed to predict carbon conversion over time for entrained flow gasification of Victorian brown coal chars at 1000–1400℃.展开更多
In this study, the mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor were investigated through thermal decomposition methods. The results show that the mercury adsorption performa...In this study, the mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor were investigated through thermal decomposition methods. The results show that the mercury adsorption performance of the HBr-modified fly ash was enhanced significantly. The mercury species adsorbed by unmodified fly ash were Hg Cl2,Hg S and Hg O. The mercury adsorbed by HBr-modified fly ash, in the entrained-flow reactor,existed in two forms, Hg Br2 and Hg O, and the HBr was the dominant factor promoting oxidation of elemental mercury in the entrained-flow reactor. In the current study, the concentration of Hg Br2 and Hg O in ash from the fine ash vessel was 4.6 times greater than for ash from the coarse ash vessel. The fine ash had better mercury adsorption performance than coarse ash, which is most likely due to the higher specific surface area and longer residence time.展开更多
The mixer-settler is a core device of solvent extraction for separating rare earth elements. There are some adverse effects like high rare earth accumulation and poor production efficiency during industrial production...The mixer-settler is a core device of solvent extraction for separating rare earth elements. There are some adverse effects like high rare earth accumulation and poor production efficiency during industrial production. Current researches usually focus on changing the structure of the mixer-settler without making a breakthrough towards gravity clarification. In this paper, in order to improve the efficiency of clarification, a mixer-settler with double stirring mode was designed and manufactured by adding a stirring device in the settler after reducing the volume of the settler. The innovation of this research involves adopting the ultraviolet-visible spectrophotometer to investigate the quantity of aqueous phase entrainment at the settler outlet in order to measure the clarification degree. Experimental results show that the clarification effect with stirring is better than that without stirring. The clarification effect is ameliorated as the stirring speed increases. Generally, the clarification effect shows a best condition when the offset distance is 12.5 cm, making the phase entrainment reduced to less than 0.1%. When the clearance over the tank bottom is 7 cm and 10 cm, respectively, the quantity of aqueous phase entrainment is better than the case with a clearance of 4 cm. The results show that the stirring paddle close to the mixed phase zone can better promote the two-phase separation.展开更多
Gasification technology is suggested to utilize asphalt particles, which are produced in the heavy oil deep separation process of using coupled low temperature separation of solvent and post extraction residue. In thi...Gasification technology is suggested to utilize asphalt particles, which are produced in the heavy oil deep separation process of using coupled low temperature separation of solvent and post extraction residue. In this work, the asphalt particles were first slurried with water and then gasified to produce synthesis gas. The gasification process of asphalt water slurry in an entrained flow gasifier was simulated using a three-dimensional computational fluid dynamics （CFD） model based on an Eulerian- Lagrangian method. The trajectories and residence time of asphalt particles, and the reaction rates, gas species distribution, temperature field and carbon conversion in the entrained flow gasifier were obtained. The predicted results indicated that the asphalt water slurry was a good feedstock for gasification. Moreover, the effects of particle size, oxygen equivalence ratio, and mass content of asphalt particles on the gasification performance of asphalt water slurry were investigated. These results are helpful for industrial application of asphalt water slurry gasification technology.展开更多
Dropshafts are vertical structures widely used in urban drainage systems and buildings for water transportation.In this paper,a physical model study was conducted to investigate the air entrainment in the dropshaft un...Dropshafts are vertical structures widely used in urban drainage systems and buildings for water transportation.In this paper,a physical model study was conducted to investigate the air entrainment in the dropshaft under various flow regimes with and without air ventilation.Observed from the experiments,the air entrainment mechanisms varied with the water flow regimes in the dropshaft.When there was no water plug formed in the dropshaft,air could be supplied directly from downstream.Once the water plug was formed,while without venting,the air was replenished only from downstream intermittently and then in the form of large air bubble traveling upwards to the airspace at the top;while with venting,air was mainly replenished from the dropshaft top and no large air bubble was observed.The experimental results also showed that the amount of entrained air in the dropshaft with venting was greater than that without venting.展开更多
基金Project supported by the graduate training funds of Shanghai Ocean University in China。
文摘The circadian system of mammals is composed of a hierarchical network of oscillators,including a core clock and peripheral clocks.The core clock receives an external photic signal and transmits it to the peripheral clocks,which,in turn,feed back to the core clock.Aging affects various functions of organisms including the circadian system.Entrainment displays the adaptability of the circadian system to changes in the external environment.However,there is currently no systematic study on the effects of aging on the entrainment capability.To explore the influencing mechanism,we develop a mathematical model of two populations of Goodwin oscillators,which represent the core clock and peripheral clocks.Based on numerical simulations,we conduct a detailed study on the impact of three aging-related factors on the entrainment capability represented by the entrainment range,entrainment time,and entrainment phase.The results indicate that the decrease in the sensitivity of suprachiasmatic nucleus(SCN)to light and the coupling strength from the SCN to the peripheral clocks due to aging increase the phase difference between the core and peripheral clocks,narrow the entrainment range,and prolong the entrainment time.A reduction in the coupling strength within the SCN has little effect on the three aspects mentioned above but increases the entrainment phase.Overall,aging reduces the circadian system's adaptability to the external environment,and the increased entrainment phase may lead to corresponding sleep problems.We also show that modulating the internal coupling strength in the peripheral clocks can mitigate aging effects;this provides an idea for using peripheral clocks to adjust the core clock,while also revealing new insights into the interaction between aging and the elasticity of the circadian system.This mechanism provides theoretical support for treating or alleviating circadian system disorders or sleep problems caused by aging.
基金funding from the European Union’s Horizon 2020 Marie Sklodowska-Curie Actions (MSCA), Innovative Training Networks (ITN), H2020-MSCA-ITN-2020 grant agreement(No.955805)。
文摘In froth flotation,overall recovery of the floatable particles consists of true recovery and recovery by entrainment,where entrainment refers to the non-selective recovery of particles in the concentrate.To understand and optimize the flotation process with regard to process conditions,it is essential to distinguish true flotation recovery from overall recovery.The established methods rely on tailored flotation experiments,unrealistic flotation conditions,or using external tracers which can be different in density and crystal structure to the mineral(s) of interest.This study presents an approach to utilize naturally occuring suitable tracers to estimate the entrainment component from overall recovery of individual particles by establishing a relationship between their settling velocity coefficient and recovery probability.Recovery probabilities of individual particles are computed using particle-based separation modelling.The approach is demonstrated for a copper ore,where naturally occurring rutile was used as the tracer to determine the entrained component of the overall recovery of chalcopyrite particles.Laboratory flotation experiments revealed that entrainment accounted for up to 6% of the overall recovery probability of fully liberated chalcopyrite particles in the fine size fractions.This approach provides a practical method for entrainment correction enabling a more accurate evaluation of true flotation recovery.
文摘Background: Brainwave entrainment using binaural beats has shown potential in treating tinnitus, but most studies have focused on one-month treatment durations. Objective: This study aimed to evaluate the time-bound efficacy of brainwave entrainment using binaural beats, comparing it to a standard tinnitus masker over a three-month duration. Method: Sixty-three individuals having tinnitus with normal hearing sensitivity were enrolled in the study. The participants were categorized into groups Ⅰ, Ⅱ, and Ⅲ. They were provided with delta(4 Hz) and alpha(10 Hz) frequency binaural beats and standard tinnitus masker, respectively, for a duration of three months. The tinnitus handicap inventory(THI) scores, Visual analogue scale(VAS) rating for tinnitus distress, and quality of life parameters were measured. The reductions obtained for each measure during the end of the first, second and third month were measured and compared across the groups. Results: All three groups showed considerable reductions in THI and VAS scores and improvements in the quality of life domains, focusing on physical and psychological health. However, groups Ⅰ and Ⅱ, who received binaural beats stimuli, showed higher benefits than those who received standard tinnitus masker. Conclusion: The results of the current study indicated that binaural beats can be an effective treatment technique for individuals with tinnitus having normal hearing sensitivity. Clinicians and otology/audiology practitioners shall adopt this innovative treatment after further validating these findings.
基金supported by the National Natural Science Foundation of China(22168032,21968024)the National Key Research and Development Program of China(2023YFC3904302).
文摘Soot is a flocculent carbon nanoparticle that results the imperfect combustion of fossil fuel,and numerous studies are dedicated to the reduction of soot production to alleviate the associated environmental problems.However,soot as a functional material is also widely used in energy storage and superhydrophobic materials.As a partial oxidation technology,the entrained flow coal gasification process will produce part of the soot.It is important to separate soot from the coal gasification fine slag(CGFS)and understand its structural characteristics for soot utilization.For this purpose,two industrial typical pulverized coal gasification fine slag(PCGFS)and coal-water slurry gasification fine slag(WCGFS)were selected for this study.The results showed that both fine slags were rich in soot,and the dry ash free mass fraction of soot in PCGFS and WCGFS was 6.24%and 2.91%,respectively,and the soot of PCGFS had a hollow carbon nanosphere morphology,while the soot of WCGFS showed a flocculent irregular morphology.The average fringe length,fringe tortuosity,and fringe spacing of the soot were 0.84 nm,1.21,and 0.45 nm,respectively.Compared to the WCGFS,the soot particles of PCGFS have less continuity of molecular bonds within the lattice,the larger the defects within the lattice,the fewer isolated lattice carbon layers there are.This study provides important theoretical support for understanding the structural characteristics and next applications of soot in the entrained flow coal gasification fine slag.
基金supported by the National Natural Science Foundation of China(52479068)Open Fund Research from the State Key Laboratory of Hydraulics and Mountain River Engineering(SKHL2323).
文摘This study investigates the air–water interaction dynamics in jet streams,with particular emphasis on the transition from the cavity to the far-field regions.A dual-tip conductivity phase-detection probe was employed to analyze four distinct downstream water levels.Based on the development of the cross-sectional mean air concentration,the jet flow was divided into four distinct regions:the jet length region,impact region,splash region,and far-field region.The results demonstrate varying trends in the evolution of the mean air concentration and maximum bubble frequency.Downstream water levels exerted a significant influence on these parameters in the splash and far-field regions,whereas minimal variation was observed in the impact region.Additionally,notable differences were identified in the probability density function of water droplets between the cavity and downstream regions.Furthermore,downstream water depth was found to have a negligible effect on the proportion of small-sized droplets in both the impact and splash regions.
基金supported by the National Natural Science Foundation of China(Grant Nos.42175099,42027804,42075073)the Innovative Project of Postgraduates in Jiangsu Province in 2023(Grant No.KYCX23_1319)+3 种基金supported by the National Natural Science Foundation of China(Grant No.42205080)the Natural Science Foundation of Sichuan(Grant No.2023YFS0442)the Research Fund of Civil Aviation Flight University of China(Grant No.J2022-037)supported by the National Key Scientific and Technological Infrastructure project“Earth System Science Numerical Simulator Facility”(Earth Lab)。
文摘The process of entrainment-mixing between cumulus clouds and the ambient air is important for the development of cumulus clouds.Accurately obtaining the entrainment rate(λ)is particularly important for its parameterization within the overall cumulus parameterization scheme.In this study,an improved bulk-plume method is proposed by solving the equations of two conserved variables simultaneously to calculateλof cumulus clouds in a large-eddy simulation.The results demonstrate that the improved bulk-plume method is more reliable than the traditional bulk-plume method,becauseλ,as calculated from the improved method,falls within the range ofλvalues obtained from the traditional method using different conserved variables.The probability density functions ofλfor all data,different times,and different heights can be well-fitted by a log-normal distribution,which supports the assumed stochastic entrainment process in previous studies.Further analysis demonstrate that the relationship betweenλand the vertical velocity is better than other thermodynamic/dynamical properties;thus,the vertical velocity is recommended as the primary influencing factor for the parameterization ofλin the future.The results of this study enhance the theoretical understanding ofλand its influencing factors and shed new light on the development ofλparameterization.
基金sponsored by the National Natural Science Foundation of China(Grant No.40975004)the State Key Basic Program(973)(Grant No.2013CB430100)
文摘Following the parameterization of sheared entrainment obtained in the companion paper, Liu et al. （2016）, the present study aims to further investigate the characteristics of entrainment, and develop a simple model for predicting the growth rate of a well-developed and sheared CBL. The relative stratification, defined as the ratio of the stratification in the free atmosphere to that in the entrainment zone, is found to be a function of entrainment flux ratio （Ae）. This leads to a simple expression of the entrainment rate, in which Ae needs to be parameterized. According to the results in Liu et al. （2016）, Ae can be simply expressed as the ratio of the convective velocity scale in the sheared CBL to that in the shear-free CBL. The parameterization of the convective velocity scale in the sheared CBL is obtained by analytically solving the bulk model with several assumptions and approximations. Results indicate that the entrainment process is influenced by the dynamic effect, the interaction between mean shear and environmental stratification, and one other term that includes the Coriolis effect. These three parameterizations constitute a simple model for predicting the growth rate of a well-developed and sheared CBL. This model is validated by outputs of LESs, and the results show that it performs satisfactorily. Compared with bulk models, this model does not need to solve a set of equations for the CBL. It is more convenient to apply in numerical models.
基金funded by the National Natural Science Foundation of China(Grant No.41801002)the National Key Foundation for Exploring Scientific Instrument Program(Grant No.42027806)+2 种基金the Natural Science Foundation of Shanxi Province(Grant No.2021JQ-452)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.2019QZKK0902)the National Key Research and Development Plan(Grant No.2018YFC1504703)。
文摘Debris flow deposits in natural channels typically have a wide grain size distribution(GSD).The effects of bed sediment GSD on the basal entrainment rate are neglected in current debris flow erosion models.Field investigations have detected three different vertical graded bedding structures:normal,inverse,and mixed-gradation,characterized by discontinuous gradation sediment and almost without intermediate-sized particles.This study conducted small-scale flume experiments to investigate the debris flow resistance forces and entrainment characteristics by incorporating the effects of discontinuous grading bed sediments.Discontinuous graded bed sediments with varying fine particle content,volumetric water content(VWC),and roundness were designed for comparison.Debris flow resistance in erodible beds generally increased in the group with gravel of larger-sized coarse particle,lower roundness,and higher bed sediment VWC.For discontinuous grading bed sediment,the entrained depths increased in the group with gravel of smaller coarse particle sizes,larger amounts of fine particles,and higher sediment roundness,and decreased with larger VWCs.This abnormality may be attributed to the disproportionately large effects of viscous flow resistance in our small-scale flume tests.The maximum erosion rates of the continuous bed sediment were higher than those of the corresponding discontinuous bed sediment with the same maximum coarse gravel size.This is because,for discontinuous grading bed sediments,localized failure of intermediate-sized sediment grains may cause a large-scale collapse of the solid grain skeleton and enhance basal entrainment rates.A revised formula for calculating the debris flow entrainment rate is proposed by incorporating the kurtosis coefficient,which describes the distribution of discontinuous bed sediments and fine particle content.Our revised formula could facilitate an elaborate estimation of basin erosion and sediment runoff and reveal the development and recession of debris flow fans.
基金funded by the National Natural Science Foundation of China under Grant Nos.40830103, 40775018, 40875008 and 40605006the science plan in the Chinese Academy of Sciences (KZCX2-YW210)+2 种基金Chinese Academy of Sciences under Grant No.YZ200708through special finance from the China Meteorological Administration(GYHY200706034)the Urban Meteorological Research Foundation (UMRF200810)
文摘After the passage of a cold front, spring in northern China, the outbreak of strong wind is often accompanied by dust emissions. Through analyses of data in the atmospheric boundary layer during a typical case, it is revealed there are rather regular gust wave packets superimposed on the basic strong wind flow. The gust-wind wave packets have a period equal to around 3 6 rains and possess coherent structure. As the vertical transport of momentum is decomposed into separate parts by （a） basic flow, （b） gust-wind, and （c） turbulence, they are all in a downwards direction at the lower levels of the atmospheric boundary layer during strong wind periods. However, （a） is the largest, while （b） and （c） are comparable. All these are very different from the case of normal weather. Besides, the friction velocity at the ground surface is also much larger than that of normal weather and should be corrected by taking the contributions of the basic flow and gust-wind into account.The strong basic flow with descending motion is very favorable for soil erosion and sand/dust emissions, but suppresses the entrainment of dust particles by keeping them within the bottom levels of the atmospheric boundary layer. Owing to the coherent structure of gust-wind, dust particles can effectively overcome the systematic descending air motion and penetrate into the middle and upper levels of the atmospheric boundary layer, and then propagate further and diffuse into the troposphere where ascending air motion prevails.
文摘Trapped vortex combustor （TVC） is an advanced low-pollution gas turbine combustor, with the adoption of staged combustion technique. To achieve low-pollutant emission and better combustion performance, the proportion of the air flow in each combustion zone should be precisely determined in the design of the combustor. Due to the presence of entrainment phenomenon, the total air flow in the cavity zone is difficult to estimate. To overcome the measurement difficulty, this study adopts the indirect measurement approach in the experimental research of entrainment phenomenon in the cavity. In accordance with the measurement principle, a TVC model fueled by methane is designed. Under two experimental conditions, i.e. with and without direct air intake in the cavity, the influence of the mainstream air flow velocity, the air intake velocity in the cavity, the height of inlet channel, the structure of holder and the structural proportion of the cavity on entrainment in the cavity is studied, respectively, through experiment at atmospheric temperature and pressure. The results suggest that the air flow velocity of mainstream, the air intake velocity of the cavity and the structure of the holder exert significant influence on the air entrainment, while the influence of structural proportion of the cavity is comparatively insignificant. The square root of momentum ratio of cavity air to mainstream air could be used to analyze the correlation of the entrainment data.
基金financially supported by the China Postdoctoral Science Foundation (Nos. 2015T80039 and 2014M560890)
文摘In this study, a water/silicone oil interface was used to simulate the steel/slag interface in a converter. A high-speed camera was used to record the entrainment process of droplets when air bubbles were passed through the water/silicone oil interface. Motion parameters of the bubbles and droplets were obtained using particle kinematic analysis software, and the entrainment rate of the droplets was calculated. It was found that the entrainment rate decreased from 29.5% to 0 when the viscosity of the silicone oil was increased from 60 mPa.s to 820 mPa.s in the case of bubbles with a 5 mm equivalent diameter passing through the water/silicone oil interface. The results indicate that in- creasing the viscosity of the silicone oil is conducive to reducing the entrainment rate. The entrainment rate increased from 0 to 136.3% in the case of silicone oil with a viscosity of 60 mPa.s when the equivalent diameter of the bubbles was increased from 3 mm to 7 ram. We there- fore conclude that small bubbles are also conductive to reducing the entrainment rate. The force analysis results for the water colmnn indicate that the entrainment rate of droplets is affected by the velocity of the bubble passing through the water/silicone oil interface and that the en- trainment rate decreases with the bubble velocity.
基金sponsored by the National Natural Science Foundation of China(Grant No.40975004)the State Key Basic Program(973)Program(Grant No.2013CB430100)
文摘The entrainment flux ratio Ae and the inversion layer （IL） thickness are two key parameters in a mixed layer model. Ae is defined as the ratio of the entrainment heat flux at the mixed layer top to the surface heat flux. The IL is the layer between the mixed layer and the free atmosphere. In this study, a parameterization of Ae is derived from the TKE budget in the first- order model for a well-developed CBL under the condition of linearly sheared geostrophic velocity with a zero value at the surface. It is also appropriate for a CBL under the condition of geostrophic velocity remaining constant with height. LESs are conducted under the above two conditions to determine the coefficients in the parameterization scheme. Results suggest that about 43% of the shear-produced TKE in the IL is available for entrainment, while the shear-produced TKE in the mixed layer and surface layer have little effect on entrainment. Based on this scheme, a new scale of convective turbulence velocity is proposed and applied to parameterize the IL thickness, The LES outputs for the CBLs under the condition of linearly sheared geostrophic velocity with a non-zero surface value are used to verify the performance of the parameterization scheme. It is found that the parameterized Ae and IL thickness agree well with the LES outputs.
基金Project supported by the National Basic Research Program (973) of China (No. G1999022211) and the National Natural Science Founda-tion of China (No. N59836210)
文摘Entrained flow adsorption using activated carbon as the adsorbent is widely adopted for PCDDs/Fs-abatement in municipal solid waste incineration (MSWI) process. The effects of operating parameters including flue gas temperature, feeding rate of activated carbon, polychlorinated dibenzodioxins and polychlorinated dibenzofurans (PCDDs/Fs) concentration at the inlet of the air pollution control device (APCD), filter materials, pressure drop on PCDDs/Fs removal efficiency are reviewed and commented upon in this paper. Evaluation on the various mechanistic models for entrained flow adsorption is carried out based on the computational simulation in terms of the actual operating condition and theoretical analysis. Finally, an advancement of en- trained flow adsorption in combination of dual bag filter is introduced.
文摘The role of several parameters on gangue recovery in froth was investigated. Effects of frother type and collector dosage on flotation performance were tested at pH 10. The results were evaluated statistically by two-way analysis of variance without replicates, sample range and sample standard deviation. Hydrophilic mineral was recovered mainly by entrainment through hydrophobization of Ca＋2-activated quartz from tap-water in the presence of Na-oleate as collector; entrapment and slime coating were also proposed as recovery mechanisms in minority. Degree of gangue-entrainment in froth product increases by reduction in liberation size. The experimental results state that selectivity would be improved by increasing collector concentration and reducing the flotation time.
基金This paper was supported by the National Natural Science Foundation of China under Grant Nos.40105002 and 40333027.
文摘It has been noted that when the convective Richardson number Ri* is used to characterize the depth of the entrainment zone, various parameterization schemes can be obtained. This situation is often attributed to the invalidity of parcel theory. However, evidence shows that the convective Richardson number Ri* might be an improper characteristic scaling parameter for the entrainment process. An attempt to use an innovative parameter to parameterize the entrainment-zone thickness has been made in this paper. Based on the examination of the data of water-tank experiments and atmospheric measurements, it is found that the total lapse rate of potential temperature across the entrainment zone is proportional to that of the capping inversion layer. Inserting this relationship into the so-called parcel theory, it thus gives a new parameterization scheme for the depth of the entrainment zone. This scheme includes the lapse rate of the capping inversion layer that plays an important role in the entrainment process. Its physical representation is reasonable. The new scheme gives a better ordering of the data measured in both water-tank and atmosphere as compared with the traditional method using Ri*. These indicate that the parcel theory can describe the entrainment process suitably and that the new parameter is better than Ri*.
文摘The gasification kinetic modelling of two Victorian brown coal(Yallourn and Maddingley)chars and the validity for entrained flow gasification were investigated in this study.The study was conducted in a thermogravimetric analyzer(TGA)at 750–1100℃,30%–90%CO_(2)concentration using different char particle sizes within 20–106 mm.It was found that random pore model and modified volumetric model are applicable for TGA results,but volumetric model and grain model are not.The effect of particle size under106 mm on gasification rate is very limited.Activation energies of Maddingley char and Yallourn char in CO_(2)gasification are 219–220 and 197–208 k J/mol,respectively.The pre-exponential factors are in the same order of magnitude,and they increased as particle size decreased.A mathematical model was developed to predict carbon conversion over time for entrained flow gasification of Victorian brown coal chars at 1000–1400℃.
基金Financial support from the National High Technology Research and Development Program of China (No. 2013AA065404)Program of Introducing Talents of Discipline to Universities of China (111 Project, B12034)Fundamental Research Funds for the Central Universities (13ZD04) is gratefully acknowledged
文摘In this study, the mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor were investigated through thermal decomposition methods. The results show that the mercury adsorption performance of the HBr-modified fly ash was enhanced significantly. The mercury species adsorbed by unmodified fly ash were Hg Cl2,Hg S and Hg O. The mercury adsorbed by HBr-modified fly ash, in the entrained-flow reactor,existed in two forms, Hg Br2 and Hg O, and the HBr was the dominant factor promoting oxidation of elemental mercury in the entrained-flow reactor. In the current study, the concentration of Hg Br2 and Hg O in ash from the fine ash vessel was 4.6 times greater than for ash from the coarse ash vessel. The fine ash had better mercury adsorption performance than coarse ash, which is most likely due to the higher specific surface area and longer residence time.
基金supported by Hi-Tech Research and Development Program(863)of China(2010AA03A405)the National Natural Science Foundation of China(No.50974035,No.51004033)
文摘The mixer-settler is a core device of solvent extraction for separating rare earth elements. There are some adverse effects like high rare earth accumulation and poor production efficiency during industrial production. Current researches usually focus on changing the structure of the mixer-settler without making a breakthrough towards gravity clarification. In this paper, in order to improve the efficiency of clarification, a mixer-settler with double stirring mode was designed and manufactured by adding a stirring device in the settler after reducing the volume of the settler. The innovation of this research involves adopting the ultraviolet-visible spectrophotometer to investigate the quantity of aqueous phase entrainment at the settler outlet in order to measure the clarification degree. Experimental results show that the clarification effect with stirring is better than that without stirring. The clarification effect is ameliorated as the stirring speed increases. Generally, the clarification effect shows a best condition when the offset distance is 12.5 cm, making the phase entrainment reduced to less than 0.1%. When the clearance over the tank bottom is 7 cm and 10 cm, respectively, the quantity of aqueous phase entrainment is better than the case with a clearance of 4 cm. The results show that the stirring paddle close to the mixed phase zone can better promote the two-phase separation.
基金support by the National Basic Research Program (Grant No. 2010CB226906)the Science Foundation of China University of Petroleum, Beijing (No. KYJJ2012-03-01)
文摘Gasification technology is suggested to utilize asphalt particles, which are produced in the heavy oil deep separation process of using coupled low temperature separation of solvent and post extraction residue. In this work, the asphalt particles were first slurried with water and then gasified to produce synthesis gas. The gasification process of asphalt water slurry in an entrained flow gasifier was simulated using a three-dimensional computational fluid dynamics （CFD） model based on an Eulerian- Lagrangian method. The trajectories and residence time of asphalt particles, and the reaction rates, gas species distribution, temperature field and carbon conversion in the entrained flow gasifier were obtained. The predicted results indicated that the asphalt water slurry was a good feedstock for gasification. Moreover, the effects of particle size, oxygen equivalence ratio, and mass content of asphalt particles on the gasification performance of asphalt water slurry were investigated. These results are helpful for industrial application of asphalt water slurry gasification technology.
基金the financial support from the China Scholarship Councilthe Natural Sciences and the Engineering Research Council (NSRC) of Canada
文摘Dropshafts are vertical structures widely used in urban drainage systems and buildings for water transportation.In this paper,a physical model study was conducted to investigate the air entrainment in the dropshaft under various flow regimes with and without air ventilation.Observed from the experiments,the air entrainment mechanisms varied with the water flow regimes in the dropshaft.When there was no water plug formed in the dropshaft,air could be supplied directly from downstream.Once the water plug was formed,while without venting,the air was replenished only from downstream intermittently and then in the form of large air bubble traveling upwards to the airspace at the top;while with venting,air was mainly replenished from the dropshaft top and no large air bubble was observed.The experimental results also showed that the amount of entrained air in the dropshaft with venting was greater than that without venting.
