On the basis of Navier-Stockes equation and convection-diffusion equation, combined with surface tension and penetration models, the equations of moment and mass transfer between bubble and the ambient non-Newtonian l...On the basis of Navier-Stockes equation and convection-diffusion equation, combined with surface tension and penetration models, the equations of moment and mass transfer between bubble and the ambient non-Newtonian liquid were established. The formation of a single bubble from a submersed nozzle of 1.0 mm diameter and the mass transfer from an artificially fixed bubble into the ambient liquid were simulated by the volume-of-fluid （VOF） method. Good agreement between simulation results and experimental data confirmed the validity of the numerical method. Furthermore, the concentration distribution around rising bubbles in shear thinning non-Newtonian fluid was simulated. When the process of a single ellipsoidal bubble with the bubble deformation rate below 2.0 rises, the concentration distribution is a single-tail in the bubble＇s wake, but it is fractal when thebubble deformation rate is greater than 2.0. For the overtaking of two in-line rising bubbles, the concentration distribution area between two bubbles broadens gradually and then coalescence occurs. The bifurcation of concentration distribution appears in the rear of the resultant bubble.展开更多
The dynamic behavior of the moving liquid column coalescing with a sessile droplet in triangular microchannels is numerically investigated by using coupled volume of fluid with level set interface tracking method impl...The dynamic behavior of the moving liquid column coalescing with a sessile droplet in triangular microchannels is numerically investigated by using coupled volume of fluid with level set interface tracking method implemented in ANSYS Fluent 14.5 in conjunction with the continuum surface force model. It is found that for both hydrophobic and hydrophilic microchannels, the coalescence between the moving liquid column and droplet can accelerate the original liquid column movement as a result of the induced curvature that lowers the liquid pressure at the interface. As compared to the rectangular microchannel with the same hydraulic diameter, the triangular microchannel exhibits smaller velocity increment ratio because of stronger viscous effect. Simulation results also reveal that the velocity increment ratio increases with the contact angle in hydrophobic microchannels, but it is reverse in the hydrophilic microchannels. The effects of the droplet size, lengthways and transverse positions are also investigated in this work. It is shown that larger droplet and smaller distance between the droplet and inlet or the substrate center can result in larger velocity increment ratio as a result of higher surface energy and lower viscous dissipation energy, respectively. The results obtained in this study create a solid theoretical foundation for designingand optimizing microfluidic devices encountering such a typical phenomenon.展开更多
In petroleum,mercaptan impurities generate malodorous fumes that pose risks to both human health and the environment,and leading to substandard oil quality.Lye desulfurization is a widely employed technique for elimin...In petroleum,mercaptan impurities generate malodorous fumes that pose risks to both human health and the environment,and leading to substandard oil quality.Lye desulfurization is a widely employed technique for eliminating mercaptans from oil.In traditional scrubber towers,lye and oil are poorly mixed,the desulfurization efficiency is low,and the lye consumption is high.To enhance washing efficiency,a droplet micromixer and corresponding fiber coalescence separator were developed.By optimizing the structure and operating parameters,more effective mixing and separation were achieved,and both caustic washing and desulfurization were enhanced.The proposed mixer/separator outperforms the industry standard by reducing the caustic loading by 30%and offers superior economic and engineering performances.The results of this study offer a direction for designing and optimizing a mercaptan removal unit to enhance the scrubbing effectiveness and decrease expenses to achieve more efficient and green production process.展开更多
The limitations of swirl separation in removing microfine oil droplets in water have driven the development of hydrocyclone technology coupled with multiphase or multifield techniques.To enhance microfine oil droplets...The limitations of swirl separation in removing microfine oil droplets in water have driven the development of hydrocyclone technology coupled with multiphase or multifield techniques.To enhance microfine oil droplets separation,a novel hydrocyclone separation coupled with fiber coalescence(HCCFC) was designed.The interaction between fiber balls and oil droplets inside the hydrocyclone,including droplet coalescence and breakage,was investigated.The influence of different operating parameters on separation efficiency was discussed.The results showed that fiber balls promoted oil droplet coalescence when the inlet droplet size(D_(43)) was below 22.37 μm but caused droplet breakage above this threshold.The coalescence performance of HCCFC improved with increasing inlet oil content but declined beyond 450 mg·L^(-1).Separation experiments confirmed that HCCFC outperformed conventional hydrocyclone,with separation efficiency increasing by 2.9% to 20.0%.As the fiber ball content and inlet flow rate increased,the separation efficiency showed a trend of first increasing and then decreasing.Additionally,HCCFC's separation efficiency varied with inlet oil droplet size distribution,showing the most significant enhancement when D_(43) was 22.37 μm,where separation efficiency increased by 14.4%.These findings offer insights into the development and application of multiphase coupled with hydrocyclone technology.展开更多
This study aims to investigate the production of light nuclei,hypertritons,and Ω-hypernuclei in Pb+Pb collisions at √S_(NN)=5.02TeV TeV using a modified analytical nucleon coalescence model with hyperons.To this end...This study aims to investigate the production of light nuclei,hypertritons,and Ω-hypernuclei in Pb+Pb collisions at √S_(NN)=5.02TeV TeV using a modified analytical nucleon coalescence model with hyperons.To this end,the momentum distributions of two bodies coalescing into dibaryon states and of three bodies coalescing into tribaryon states are derived.Available data on coalescence factors B_(2) and B_(3),transverse momentum spectra,averaged transverse momenta,yield rapidity densities,and yield ratios of the deuteron,antihelium-3,antitriton,and hypertriton measured by the ALICE collaboration are explained.Productions of different species of Ω-hypernuclei H(pΩ^(−)),H(nΩ^(−)),and H(pnΩ^(−))are predicted.Particularly,the production correlations of different light(hyper-)nuclei are studied,and two groups of interesting observables-the averaged transverse momentum ratios of light(hyper-)nuclei to protons(hyperons)and their corresponding yield ratios-are studied.The averaged transverse momentum ratio group exhibits a reverse hierarchy of the nucleus size,and the yield raito group is sensitive to the nucleus production mechanism as well as the size of the nucleus.展开更多
A coalescence model was employed to form deuterons(d),tritons(t),and helium-3(^(3)He)nuclei from a uniformly-distributed volume of protons(p)and neutrons(n).We studied the ratio N_(t)N_(p)/N_(d)^(2)of light nuclei yie...A coalescence model was employed to form deuterons(d),tritons(t),and helium-3(^(3)He)nuclei from a uniformly-distributed volume of protons(p)and neutrons(n).We studied the ratio N_(t)N_(p)/N_(d)^(2)of light nuclei yields as a function of the neutron density fluctuations.We investigated the effect of finite transverse momentum(p_(T))acceptance on the ratio,in particular,the“extrapolation factor”(f)for the ratio as a function of the p_(T)spectral shape and the magnitude of neutron density fluctuations.The nature of f was found to be monotonic in p_(T)spectra“temperature”parameter and neutron density fluctuation magnitude;variations in the latter are relatively small.We also examined f in realistic simulations using the kinematic distributions of protons measured from the heavy-ion collision data.The nature of f was found to be smooth and monotonic as a function of the beam energy.Therefore,we conclude that extrapolation from limited p_(T)ranges does not create,enhance,or reduce the local peak of the N_(t)N_(p)/N_(d)^(2)ratio in the beam energy.Our study provides a necessary benchmark for light nuclei ratios as a probe for nucleon density fluctuations,an important observation in the search for the critical point of nuclear matter.展开更多
During the excavation of deep engineering,high in situ stress is one prominent feature that often causes instability in the vicinity of underground openings.The propagation and coalescence of cracks in the surrounding...During the excavation of deep engineering,high in situ stress is one prominent feature that often causes instability in the vicinity of underground openings.The propagation and coalescence of cracks in the surrounding rock are characterized by anisotropy under a true triaxial stress state and play a crucial role in the development of stress-induced engineering disasters.Thus,a three-dimensional anisotropic fracturing model of hard rock is proposed to interpret fracturing activities and evaluate the mechanical property deterioration under complex stress conditions.This anisotropic fracturing model is derived from the evolution of microcracks and attributes the inelastic deformation of hard rock to crack propagation and coalescence.Through analyzing the competitive process of crack propagation in different orientations,the stress-induced anisotropic fracturing characteristics and the post-peak brittle-ductile transition could be revealed.Finally,the accuracy and effectiveness of this model are validated.Results show that this proposed anisotropic fracturing model can elucidate the primary characteristics observed in triaxial compression tests,which offers a fresh perspective on comprehending the failure process of hard rock.展开更多
Geomorphological and Quaternarygeological field- and laboratory data (Fig.1) are introduced and interpreted with regard to the maximum Ice Age (LGM) glaciation of the Central-and South Karakoram in the Braldu-, Basna-...Geomorphological and Quaternarygeological field- and laboratory data (Fig.1) are introduced and interpreted with regard to the maximum Ice Age (LGM) glaciation of the Central-and South Karakoram in the Braldu-, Basna-, Shigar-and Indus valley system as well as on the Deosai plateau between the Skardu Basin and the Astor valley (Fig.2). These data result from two research expeditions in the years 1997 and 2000. They show that between c. 60 and 20 Ka the Central Karakorum and its south slope were covered by a continuous c. 125,000 km2 sized ice stream network. This ice stream network flowed together to a joint parent glacier, the Indus glacier. The tongue end of the Indus glacier reached down to 850 ～ 800 m a.s.l. In its centre the surface of this Indus ice stream network reached a height of a good 6000 m. Its most important ice thicknesses amounted to c. 2400 ～ 2900 m.展开更多
There exists an inherent difficulty in the original algorithm for the construction of Dwarf, which prevents it from constructing true Dwarfs. We explained when and why it introduces suffix redundancies into the Dwarf ...There exists an inherent difficulty in the original algorithm for the construction of Dwarf, which prevents it from constructing true Dwarfs. We explained when and why it introduces suffix redundancies into the Dwarf structure. To solve this problem, we proposed a completely new algorithm called PID. It bottom-up computes partitions of a fact table, and inserts them into the Dwarf structure. If a partition is an MSV partition, coalesce its sub-Dwarf; otherwise create necessary nodes and cells. Our performance study showed that PID is efficient. For further condensing of Dwarf, we proposed Condensed Dwarf, a more com- pressed structure, combining the strength of Dwarf and Condensed Cube. By eliminating unnecessary stores of “ALL” cells from the Dwarf structure, Condensed Dwarf could effectively reduce the size of Dwarf, especially for Dwarfs of the real world, which was illustrated by our experiments. Its query processing is still simple and, only two minor modifications to PID are required for the construction of Condensed Dwarf.展开更多
Natural gas is increasingly recognized as a clean energy source due to its high quality,low pollution levels,and abundant availability.However,certain gas fields contain complex components that require purification fo...Natural gas is increasingly recognized as a clean energy source due to its high quality,low pollution levels,and abundant availability.However,certain gas fields contain complex components that require purification for efficient transportation and utilization.Addressing these issues involves efficient gas eliquid separation technology.Existing gaseliquid separation units face challenges such as efficiency,liquid entrainment,energy consumption,and the need for consumable replacement.This study focuses on a novel cyclone-coalescence separator that combines centrifugal and coalescence principles.Implemented in a high-acid natural gas purification plant in China,the cyclone-coalescence separator demonstrated efficiency primarily influenced by gas velocity and diameter.Optimal performance was observed with a 75 mm diameter reactor at velocities of 8-12 m·s^(-1),achieving a peak efficiency of 96%.The hydrophilic glass fiber with a monofilament structure can coalesce droplets effectively.In practical industrial use,under operational conditions,the hydrocyclone's liquid discharge rate is 89.6 kg·h^(-1)with an inlet concentration of 382.7 g·m^(3).Over a 400-h cycle,the cyclone-coalescence separator demonstrated superior separation performance with an average liquid discharge volume of 9.09 mg·kg^(-1),compared to 4.93 mg·kg^(-1)for the precision filter.This successful industrial implementation presents a promising approach to natural gas purification.展开更多
A novel method for breaking emulsions with microporous membranes is presented.A membrane would act as a coalescer if its pore size is smaller than the emulsion droplets and if the dispersed phase has great affinity to...A novel method for breaking emulsions with microporous membranes is presented.A membrane would act as a coalescer if its pore size is smaller than the emulsion droplets and if the dispersed phase has great affinity to the membrane.It was observed that a hydrophilic membrane is able to break water in oil emulsions with high separation efficiency.Effects of the membrane pore size,membrane thickness,transmembrane pressure and emulsion composition on demulsification performance were investigated.It was found that the membrane pore size and transmembrane pressure affect demulsification performance remarkably while other factors have slight or almost no effect.展开更多
Based on the axial stress-axial strain curves,the effect of fissure angle on the strength and deformation behavior of sandstone specimens containing combined flaws is analyzed.The mechanical parameters of sandstone sp...Based on the axial stress-axial strain curves,the effect of fissure angle on the strength and deformation behavior of sandstone specimens containing combined flaws is analyzed.The mechanical parameters of sandstone specimens containing combined flaws are all lower than that of intact specimen,but the reduction extent is distinctly related to the fissure angle.The results of sandstone specimens containing combined flaws are obtained by the acoustic emission,which can be used to monitor the crack initiation and propagation.The ultimate failure mode and crack coalescence behavior are evaluated for brittle sandstone specimens containing combined flaws.Nine different crack types are identified on the basis of their geometry and crack coalescence mechanism(tensile crack,hole collapse,far-field crack and surface spalling)for combined flaws.The photographic monitoring was also adopted for uniaxial compression test in order to confirm the sequence of crack coalescence in brittle sandstone specimens containing combined flaws,which recorded the real-time crack coalescence process during entire deformation.According to the monitored results,the effect of crack coalescence process on the strength and deformation behavior is investigated based on a detailed analysis for brittle sandstone specimens containing combined flaws by using digital photogrammetry.展开更多
This paper provides an overview and a tutorial of the BPP program, which is a Bayesian MCMC program for analyzing multi-locus genomic sequence data under the multispecies coalescent model. An example dataset of five n...This paper provides an overview and a tutorial of the BPP program, which is a Bayesian MCMC program for analyzing multi-locus genomic sequence data under the multispecies coalescent model. An example dataset of five nuclear loci from the East Asian brown frogs is used to illustrate four different analyses, including estimation of species divergence times and population size parameters under the multispecies coalescent model on a fixed species phylogeny （A00）, species tree estimation when the assignment and species delimitation are fixed （A01）, species delimitation using a fixed guide tree （A10）, and joint species delimitation and species-tree estimation or unguided species delimitation （A11）. For the joint analysis （A11）, two new priors are introduced, which assign uniform probabilities for the different numbers of delimited species, which may be useful when assignment, species delimitation, and species phylogeny are all inferred in one joint analysis. The paper ends with a discussion of the assumptions, the strengths and weaknesses of the BPP analysis [Current Zoology 61 （5）： 854-865, 2015].展开更多
The mechanism of cracks propagation and cracks coalescence due to compressive loading of the brittle substances containing pre-existing cracks （flaws） was modeled experimentally using specially made rock-like specim...The mechanism of cracks propagation and cracks coalescence due to compressive loading of the brittle substances containing pre-existing cracks （flaws） was modeled experimentally using specially made rock-like specimens from Portland Pozzolana Cement （PPC）. The breakage process of the specimens was studied by inserting single and double flaws with different inclination angles at the center and applying uniaxial compressive stress at both ends of the specimen. The first crack was oriented at 50＆#176; from the horizontal direction and kept constant throughout the analysis while the orientation of the second crack was changed. It is experimentally observed that the wing cracks are produced at the first stage of loading and start their propagation toward the direction of uniaxial compressive loading. The secondary cracks may also be produced in form of quasi-coplanar and/or oblique cracks in a stable manner. The secondary cracks may eventually continue their propagation in the direction of maximum principle stress. These experimental works were also simulated numerically by a modified higher order displacement discontinuity method and the cracks propagation and cracks coalescence were studied based on Mode I and Mode II stress intensity factors （SIFs）. It is concluded that the wing cracks initiation stresses for the specimens change from 11.3 to 14.1 MPain the case of numerical simulations and from 7.3 to 13.8 MPa in the case of experimental works. It is observed that cracks coalescence stresses change from 21.8 to 25.3 MPa and from 19.5 to 21.8 MPa in the numerical and experimental analyses, respectively. Comparing some of the numerical and experimental results with those recently cited in the literature validates the results obtained by the proposed study. Finally, a numerical simulation was accomplished to study the effect of confining pressure on the crack propagation process, showing that the SIFs increase and the crack initiation angles change in this case.展开更多
Hot-extruded magnesium alloy AZ31 bar was cut into hexagonal prisms and then compressed at room temperature with the loading direction parallel to the extrusion direction(ED)or perpendicular to ED.The effective stress...Hot-extruded magnesium alloy AZ31 bar was cut into hexagonal prisms and then compressed at room temperature with the loading direction parallel to the extrusion direction(ED)or perpendicular to ED.The effective stress and strain evolution at center and corner region of the hexagonal prisms was simulated by using DEFORM 3D,while microstructure evolution was characterized by electron backscatter diffraction(EBSD).Relationship between twinning behavior and stress-strain evolution during compression at room temperature was studied.The results indicated that the compressive stress and strain levels at central region of hexagonal prisms were lower than those at the corner parts.EBSD examination revealed that{10-12}twins activate during the compression and the volume fraction of twins at corner parts were less than that at the central parts,which was attributed to twin thickening and coalescence behaviors.Meanwhile,the EBSD map indicated that the arise of{10-11}contraction twins and{10-11}-{10-12}double twins in compressed samples,especially in the corner region with loading axis perpendicular to ED,which were considered to be related to the high stress level at corner region.The dislocation slips led to low-angle boundaries in LA⊥ED and LA//ED.展开更多
A series of laboratory experiments and PFC numerical simulations for rock-like material specimens containing two unparallel fissures were carried out.On the basis of experimental and numerical results,the stress-strai...A series of laboratory experiments and PFC numerical simulations for rock-like material specimens containing two unparallel fissures were carried out.On the basis of experimental and numerical results,the stress-strain curves,mechanical properties,AE events,cracking behavior and energy characteristics were analyzed to reveal the macro-mechanical behavior and meso-mechanism of pre-fissured specimens under different loading rates.Investigated results show that:1)When the loading rate is relatively low,the stress-strain curves show a brittle response.When the loading rate is relatively high,the curve shows a more ductile response.Both of the peak strength and elastic mudulus increase with the increase of loading rate,which can be expressed as power functions.2)Four crack types are identified,i.e.,tensile crack,shear crack,far-field crack and surface spalling.Moreover,the tensile crack,far-field crack and surface spalling are under tensile mechanism,while the shear crack is under shear mechanism.3)The drops of the stress-strain curves all correspond to the crack initiation or coalescence,which is also linked to a sudden increasing in the accumulated micro-crack curve.4)Both of the maximum bond force and energy have the similar trend with the increase of loading rate to peak strength,which indicates that the trend of peak strength can be explained by the meso-mechanics and energy.展开更多
Failure of rock mass that is subjected to compressive loads occurs from initiation, propagation, and linkage of new cracks from preexisting fissures. Our research investigates the cracking behaviour and coalescence pr...Failure of rock mass that is subjected to compressive loads occurs from initiation, propagation, and linkage of new cracks from preexisting fissures. Our research investigates the cracking behaviour and coalescence process in a brittle material with two non-parallel overlapping flaws using a high-speed camera. The coalescence tensile crack and tensile wing cracks were the first cracks to occur from the preexisting flaws. The initiation stresses of the primary cracks at the two tips of each flaw were simultaneous and decreased with reduced flaw inclination angle. The following types of coalescence cracks were identified between the flaws: primary tensile coalescence crack, tensile crack linkage, shear crack linkage, mixed tensile-shear crack, and indirect crack coalescence. Coalescence through tensile linkage occurred mostly at pre-peak stress. In contrast, coalescence through shear or mixed tensile-shear cracks occurred at higher stress. Overall, this study indicates that the geometry of preexisting flaws affect crack initiation and coalescence behaviour.展开更多
Effect of frothers in preventing bubble coalescence during flotation of minerals has long been investigated.To evaluate the performance of a frother,an apparatus to measure the bubble size is a basic necessity.McGill ...Effect of frothers in preventing bubble coalescence during flotation of minerals has long been investigated.To evaluate the performance of a frother,an apparatus to measure the bubble size is a basic necessity.McGill Bubble Size Analyzer(MBSA) or bubble viewer that has been developed and completed by McGill University's Mineral Processing Group during the last decade is a unique instrument to serve this purpose.Two parameters which are thought to influence the bubble size measurements by McGill bubble viewer include water quality and frother concentration in the chamber.Results show that there is no difference in Sauter mean(D32) when tap or de-ionized water was used instead of process water.However,the frother concentration,in this research DowFroth 250(DF250),inside the chamber exhibited a pronounced effect on bubble size.Frother concentration below a certain point can not prevent coalescence inside the chamber and therefore caution must be taken in plant applications.It was also noted that the frother concentration which has been so far practiced in plant measurements(CCC75-CCC95) is high enough to prevent coalescence with the bubble viewer.展开更多
基金Supported by the National iqatural Science Foundation of China （21076139）.
文摘On the basis of Navier-Stockes equation and convection-diffusion equation, combined with surface tension and penetration models, the equations of moment and mass transfer between bubble and the ambient non-Newtonian liquid were established. The formation of a single bubble from a submersed nozzle of 1.0 mm diameter and the mass transfer from an artificially fixed bubble into the ambient liquid were simulated by the volume-of-fluid （VOF） method. Good agreement between simulation results and experimental data confirmed the validity of the numerical method. Furthermore, the concentration distribution around rising bubbles in shear thinning non-Newtonian fluid was simulated. When the process of a single ellipsoidal bubble with the bubble deformation rate below 2.0 rises, the concentration distribution is a single-tail in the bubble＇s wake, but it is fractal when thebubble deformation rate is greater than 2.0. For the overtaking of two in-line rising bubbles, the concentration distribution area between two bubbles broadens gradually and then coalescence occurs. The bifurcation of concentration distribution appears in the rear of the resultant bubble.
基金supported by the National Natural Science Foundation of China(5122260351276208 and51325602)+1 种基金the Fundamental Research Funds for the Central Universities(CDJZR12148801)Program for New Century Excellent Talents in University(NCET-12-0591)
文摘The dynamic behavior of the moving liquid column coalescing with a sessile droplet in triangular microchannels is numerically investigated by using coupled volume of fluid with level set interface tracking method implemented in ANSYS Fluent 14.5 in conjunction with the continuum surface force model. It is found that for both hydrophobic and hydrophilic microchannels, the coalescence between the moving liquid column and droplet can accelerate the original liquid column movement as a result of the induced curvature that lowers the liquid pressure at the interface. As compared to the rectangular microchannel with the same hydraulic diameter, the triangular microchannel exhibits smaller velocity increment ratio because of stronger viscous effect. Simulation results also reveal that the velocity increment ratio increases with the contact angle in hydrophobic microchannels, but it is reverse in the hydrophilic microchannels. The effects of the droplet size, lengthways and transverse positions are also investigated in this work. It is shown that larger droplet and smaller distance between the droplet and inlet or the substrate center can result in larger velocity increment ratio as a result of higher surface energy and lower viscous dissipation energy, respectively. The results obtained in this study create a solid theoretical foundation for designingand optimizing microfluidic devices encountering such a typical phenomenon.
基金supported by the National Natural Science Foundation of China(52025103)the Xplorer Prize(XPLORER-2022-1034).
文摘In petroleum,mercaptan impurities generate malodorous fumes that pose risks to both human health and the environment,and leading to substandard oil quality.Lye desulfurization is a widely employed technique for eliminating mercaptans from oil.In traditional scrubber towers,lye and oil are poorly mixed,the desulfurization efficiency is low,and the lye consumption is high.To enhance washing efficiency,a droplet micromixer and corresponding fiber coalescence separator were developed.By optimizing the structure and operating parameters,more effective mixing and separation were achieved,and both caustic washing and desulfurization were enhanced.The proposed mixer/separator outperforms the industry standard by reducing the caustic loading by 30%and offers superior economic and engineering performances.The results of this study offer a direction for designing and optimizing a mercaptan removal unit to enhance the scrubbing effectiveness and decrease expenses to achieve more efficient and green production process.
基金sponsored by the National Science Fund for Distinguished Young Scholars,China(22225804)the National Natural Science Foundation of China(22078102,22408101,22308105)。
文摘The limitations of swirl separation in removing microfine oil droplets in water have driven the development of hydrocyclone technology coupled with multiphase or multifield techniques.To enhance microfine oil droplets separation,a novel hydrocyclone separation coupled with fiber coalescence(HCCFC) was designed.The interaction between fiber balls and oil droplets inside the hydrocyclone,including droplet coalescence and breakage,was investigated.The influence of different operating parameters on separation efficiency was discussed.The results showed that fiber balls promoted oil droplet coalescence when the inlet droplet size(D_(43)) was below 22.37 μm but caused droplet breakage above this threshold.The coalescence performance of HCCFC improved with increasing inlet oil content but declined beyond 450 mg·L^(-1).Separation experiments confirmed that HCCFC outperformed conventional hydrocyclone,with separation efficiency increasing by 2.9% to 20.0%.As the fiber ball content and inlet flow rate increased,the separation efficiency showed a trend of first increasing and then decreasing.Additionally,HCCFC's separation efficiency varied with inlet oil droplet size distribution,showing the most significant enhancement when D_(43) was 22.37 μm,where separation efficiency increased by 14.4%.These findings offer insights into the development and application of multiphase coupled with hydrocyclone technology.
基金supported by the National Natural Science Foundation of China(Nos.12175115 and 12375074).
文摘This study aims to investigate the production of light nuclei,hypertritons,and Ω-hypernuclei in Pb+Pb collisions at √S_(NN)=5.02TeV TeV using a modified analytical nucleon coalescence model with hyperons.To this end,the momentum distributions of two bodies coalescing into dibaryon states and of three bodies coalescing into tribaryon states are derived.Available data on coalescence factors B_(2) and B_(3),transverse momentum spectra,averaged transverse momenta,yield rapidity densities,and yield ratios of the deuteron,antihelium-3,antitriton,and hypertriton measured by the ALICE collaboration are explained.Productions of different species of Ω-hypernuclei H(pΩ^(−)),H(nΩ^(−)),and H(pnΩ^(−))are predicted.Particularly,the production correlations of different light(hyper-)nuclei are studied,and two groups of interesting observables-the averaged transverse momentum ratios of light(hyper-)nuclei to protons(hyperons)and their corresponding yield ratios-are studied.The averaged transverse momentum ratio group exhibits a reverse hierarchy of the nucleus size,and the yield raito group is sensitive to the nucleus production mechanism as well as the size of the nucleus.
基金supported in part by the U.S.Department of Energy(No.DE-SC0012910)National Nature Science Foundation of China(Nos.12035006 and 12075085)the Ministry of Science and Technology of China(No.2020YFE020200)。
文摘A coalescence model was employed to form deuterons(d),tritons(t),and helium-3(^(3)He)nuclei from a uniformly-distributed volume of protons(p)and neutrons(n).We studied the ratio N_(t)N_(p)/N_(d)^(2)of light nuclei yields as a function of the neutron density fluctuations.We investigated the effect of finite transverse momentum(p_(T))acceptance on the ratio,in particular,the“extrapolation factor”(f)for the ratio as a function of the p_(T)spectral shape and the magnitude of neutron density fluctuations.The nature of f was found to be monotonic in p_(T)spectra“temperature”parameter and neutron density fluctuation magnitude;variations in the latter are relatively small.We also examined f in realistic simulations using the kinematic distributions of protons measured from the heavy-ion collision data.The nature of f was found to be smooth and monotonic as a function of the beam energy.Therefore,we conclude that extrapolation from limited p_(T)ranges does not create,enhance,or reduce the local peak of the N_(t)N_(p)/N_(d)^(2)ratio in the beam energy.Our study provides a necessary benchmark for light nuclei ratios as a probe for nucleon density fluctuations,an important observation in the search for the critical point of nuclear matter.
基金support from the National Natural Science Foundation of China(Grant No.52209125).
文摘During the excavation of deep engineering,high in situ stress is one prominent feature that often causes instability in the vicinity of underground openings.The propagation and coalescence of cracks in the surrounding rock are characterized by anisotropy under a true triaxial stress state and play a crucial role in the development of stress-induced engineering disasters.Thus,a three-dimensional anisotropic fracturing model of hard rock is proposed to interpret fracturing activities and evaluate the mechanical property deterioration under complex stress conditions.This anisotropic fracturing model is derived from the evolution of microcracks and attributes the inelastic deformation of hard rock to crack propagation and coalescence.Through analyzing the competitive process of crack propagation in different orientations,the stress-induced anisotropic fracturing characteristics and the post-peak brittle-ductile transition could be revealed.Finally,the accuracy and effectiveness of this model are validated.Results show that this proposed anisotropic fracturing model can elucidate the primary characteristics observed in triaxial compression tests,which offers a fresh perspective on comprehending the failure process of hard rock.
文摘Geomorphological and Quaternarygeological field- and laboratory data (Fig.1) are introduced and interpreted with regard to the maximum Ice Age (LGM) glaciation of the Central-and South Karakoram in the Braldu-, Basna-, Shigar-and Indus valley system as well as on the Deosai plateau between the Skardu Basin and the Astor valley (Fig.2). These data result from two research expeditions in the years 1997 and 2000. They show that between c. 60 and 20 Ka the Central Karakorum and its south slope were covered by a continuous c. 125,000 km2 sized ice stream network. This ice stream network flowed together to a joint parent glacier, the Indus glacier. The tongue end of the Indus glacier reached down to 850 ～ 800 m a.s.l. In its centre the surface of this Indus ice stream network reached a height of a good 6000 m. Its most important ice thicknesses amounted to c. 2400 ～ 2900 m.
基金Project (No. 20030487032) supported by the Specialized Research Fund for the Doctoral Program of Higher Education, China
文摘There exists an inherent difficulty in the original algorithm for the construction of Dwarf, which prevents it from constructing true Dwarfs. We explained when and why it introduces suffix redundancies into the Dwarf structure. To solve this problem, we proposed a completely new algorithm called PID. It bottom-up computes partitions of a fact table, and inserts them into the Dwarf structure. If a partition is an MSV partition, coalesce its sub-Dwarf; otherwise create necessary nodes and cells. Our performance study showed that PID is efficient. For further condensing of Dwarf, we proposed Condensed Dwarf, a more com- pressed structure, combining the strength of Dwarf and Condensed Cube. By eliminating unnecessary stores of “ALL” cells from the Dwarf structure, Condensed Dwarf could effectively reduce the size of Dwarf, especially for Dwarfs of the real world, which was illustrated by our experiments. Its query processing is still simple and, only two minor modifications to PID are required for the construction of Condensed Dwarf.
基金supported by the National Natural Science Foundation of China(Youth Fund)(52300136).
文摘Natural gas is increasingly recognized as a clean energy source due to its high quality,low pollution levels,and abundant availability.However,certain gas fields contain complex components that require purification for efficient transportation and utilization.Addressing these issues involves efficient gas eliquid separation technology.Existing gaseliquid separation units face challenges such as efficiency,liquid entrainment,energy consumption,and the need for consumable replacement.This study focuses on a novel cyclone-coalescence separator that combines centrifugal and coalescence principles.Implemented in a high-acid natural gas purification plant in China,the cyclone-coalescence separator demonstrated efficiency primarily influenced by gas velocity and diameter.Optimal performance was observed with a 75 mm diameter reactor at velocities of 8-12 m·s^(-1),achieving a peak efficiency of 96%.The hydrophilic glass fiber with a monofilament structure can coalesce droplets effectively.In practical industrial use,under operational conditions,the hydrocyclone's liquid discharge rate is 89.6 kg·h^(-1)with an inlet concentration of 382.7 g·m^(3).Over a 400-h cycle,the cyclone-coalescence separator demonstrated superior separation performance with an average liquid discharge volume of 9.09 mg·kg^(-1),compared to 4.93 mg·kg^(-1)for the precision filter.This successful industrial implementation presents a promising approach to natural gas purification.
文摘A novel method for breaking emulsions with microporous membranes is presented.A membrane would act as a coalescer if its pore size is smaller than the emulsion droplets and if the dispersed phase has great affinity to the membrane.It was observed that a hydrophilic membrane is able to break water in oil emulsions with high separation efficiency.Effects of the membrane pore size,membrane thickness,transmembrane pressure and emulsion composition on demulsification performance were investigated.It was found that the membrane pore size and transmembrane pressure affect demulsification performance remarkably while other factors have slight or almost no effect.
基金Project(2014CB046905,2013CB36003)supported by the National Basic Research Program of ChinaProject(NCET-12-0961)supported by the Program for New Century Excellent Talents in University,China+1 种基金Projects(51179189,41272344)supported by the National Natural Science Foundation of ChinaProject(HBKLCIV201201)supported by the Open Research Fund Program of the Key Laboratory of Safety for Geotechnical and Structural Engineering of Hubei Province,China
文摘Based on the axial stress-axial strain curves,the effect of fissure angle on the strength and deformation behavior of sandstone specimens containing combined flaws is analyzed.The mechanical parameters of sandstone specimens containing combined flaws are all lower than that of intact specimen,but the reduction extent is distinctly related to the fissure angle.The results of sandstone specimens containing combined flaws are obtained by the acoustic emission,which can be used to monitor the crack initiation and propagation.The ultimate failure mode and crack coalescence behavior are evaluated for brittle sandstone specimens containing combined flaws.Nine different crack types are identified on the basis of their geometry and crack coalescence mechanism(tensile crack,hole collapse,far-field crack and surface spalling)for combined flaws.The photographic monitoring was also adopted for uniaxial compression test in order to confirm the sequence of crack coalescence in brittle sandstone specimens containing combined flaws,which recorded the real-time crack coalescence process during entire deformation.According to the monitored results,the effect of crack coalescence process on the strength and deformation behavior is investigated based on a detailed analysis for brittle sandstone specimens containing combined flaws by using digital photogrammetry.
文摘This paper provides an overview and a tutorial of the BPP program, which is a Bayesian MCMC program for analyzing multi-locus genomic sequence data under the multispecies coalescent model. An example dataset of five nuclear loci from the East Asian brown frogs is used to illustrate four different analyses, including estimation of species divergence times and population size parameters under the multispecies coalescent model on a fixed species phylogeny （A00）, species tree estimation when the assignment and species delimitation are fixed （A01）, species delimitation using a fixed guide tree （A10）, and joint species delimitation and species-tree estimation or unguided species delimitation （A11）. For the joint analysis （A11）, two new priors are introduced, which assign uniform probabilities for the different numbers of delimited species, which may be useful when assignment, species delimitation, and species phylogeny are all inferred in one joint analysis. The paper ends with a discussion of the assumptions, the strengths and weaknesses of the BPP analysis [Current Zoology 61 （5）： 854-865, 2015].
文摘The mechanism of cracks propagation and cracks coalescence due to compressive loading of the brittle substances containing pre-existing cracks （flaws） was modeled experimentally using specially made rock-like specimens from Portland Pozzolana Cement （PPC）. The breakage process of the specimens was studied by inserting single and double flaws with different inclination angles at the center and applying uniaxial compressive stress at both ends of the specimen. The first crack was oriented at 50＆#176; from the horizontal direction and kept constant throughout the analysis while the orientation of the second crack was changed. It is experimentally observed that the wing cracks are produced at the first stage of loading and start their propagation toward the direction of uniaxial compressive loading. The secondary cracks may also be produced in form of quasi-coplanar and/or oblique cracks in a stable manner. The secondary cracks may eventually continue their propagation in the direction of maximum principle stress. These experimental works were also simulated numerically by a modified higher order displacement discontinuity method and the cracks propagation and cracks coalescence were studied based on Mode I and Mode II stress intensity factors （SIFs）. It is concluded that the wing cracks initiation stresses for the specimens change from 11.3 to 14.1 MPain the case of numerical simulations and from 7.3 to 13.8 MPa in the case of experimental works. It is observed that cracks coalescence stresses change from 21.8 to 25.3 MPa and from 19.5 to 21.8 MPa in the numerical and experimental analyses, respectively. Comparing some of the numerical and experimental results with those recently cited in the literature validates the results obtained by the proposed study. Finally, a numerical simulation was accomplished to study the effect of confining pressure on the crack propagation process, showing that the SIFs increase and the crack initiation angles change in this case.
基金The work was supported by the National Natural Science Foundation of China(No.5140115)the Promotive Research Fund for Excellent Young and Middle-aged Scientists of Shandong Province(No.BS2013CL034)+1 种基金Independent Inno-vation Foundation of Shandong University(No.GN2013001)partially by the Fundamental Research Funds of Shan-dong University(2016JC016).
文摘Hot-extruded magnesium alloy AZ31 bar was cut into hexagonal prisms and then compressed at room temperature with the loading direction parallel to the extrusion direction(ED)or perpendicular to ED.The effective stress and strain evolution at center and corner region of the hexagonal prisms was simulated by using DEFORM 3D,while microstructure evolution was characterized by electron backscatter diffraction(EBSD).Relationship between twinning behavior and stress-strain evolution during compression at room temperature was studied.The results indicated that the compressive stress and strain levels at central region of hexagonal prisms were lower than those at the corner parts.EBSD examination revealed that{10-12}twins activate during the compression and the volume fraction of twins at corner parts were less than that at the central parts,which was attributed to twin thickening and coalescence behaviors.Meanwhile,the EBSD map indicated that the arise of{10-11}contraction twins and{10-11}-{10-12}double twins in compressed samples,especially in the corner region with loading axis perpendicular to ED,which were considered to be related to the high stress level at corner region.The dislocation slips led to low-angle boundaries in LA⊥ED and LA//ED.
基金Project(BK20150005) supported by the Natural Science Foundation of Jiangsu Province for Distinguished Young Scholars,ChinaProject(2014YC10) supported by the Fundamental Research Funds for the Central Universities,China
文摘A series of laboratory experiments and PFC numerical simulations for rock-like material specimens containing two unparallel fissures were carried out.On the basis of experimental and numerical results,the stress-strain curves,mechanical properties,AE events,cracking behavior and energy characteristics were analyzed to reveal the macro-mechanical behavior and meso-mechanism of pre-fissured specimens under different loading rates.Investigated results show that:1)When the loading rate is relatively low,the stress-strain curves show a brittle response.When the loading rate is relatively high,the curve shows a more ductile response.Both of the peak strength and elastic mudulus increase with the increase of loading rate,which can be expressed as power functions.2)Four crack types are identified,i.e.,tensile crack,shear crack,far-field crack and surface spalling.Moreover,the tensile crack,far-field crack and surface spalling are under tensile mechanism,while the shear crack is under shear mechanism.3)The drops of the stress-strain curves all correspond to the crack initiation or coalescence,which is also linked to a sudden increasing in the accumulated micro-crack curve.4)Both of the maximum bond force and energy have the similar trend with the increase of loading rate to peak strength,which indicates that the trend of peak strength can be explained by the meso-mechanics and energy.
基金supported by the National Natural Science Foundation of China (Grants 41572310, 41272351)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grants XDB10030301, XDB10030304)support provided by the CAS-TWAS Presidential Fellowship, University of Chinese Academy of Sciences, Beijing, China
文摘Failure of rock mass that is subjected to compressive loads occurs from initiation, propagation, and linkage of new cracks from preexisting fissures. Our research investigates the cracking behaviour and coalescence process in a brittle material with two non-parallel overlapping flaws using a high-speed camera. The coalescence tensile crack and tensile wing cracks were the first cracks to occur from the preexisting flaws. The initiation stresses of the primary cracks at the two tips of each flaw were simultaneous and decreased with reduced flaw inclination angle. The following types of coalescence cracks were identified between the flaws: primary tensile coalescence crack, tensile crack linkage, shear crack linkage, mixed tensile-shear crack, and indirect crack coalescence. Coalescence through tensile linkage occurred mostly at pre-peak stress. In contrast, coalescence through shear or mixed tensile-shear cracks occurred at higher stress. Overall, this study indicates that the geometry of preexisting flaws affect crack initiation and coalescence behaviour.
基金Project supported by the Chair in Mineral Processing at McGill University,under the Collaborative Research and Development Program of NSERC(Natural Sciences and Engineering Research Council of Canada)with industrial sponsorship from Vale,Teck Cominco,Xstrata Process Support,Agnico-Eagle,Shell Canada,Barrick Gold,COREM,SGS Lakefield Research and Flottec
文摘Effect of frothers in preventing bubble coalescence during flotation of minerals has long been investigated.To evaluate the performance of a frother,an apparatus to measure the bubble size is a basic necessity.McGill Bubble Size Analyzer(MBSA) or bubble viewer that has been developed and completed by McGill University's Mineral Processing Group during the last decade is a unique instrument to serve this purpose.Two parameters which are thought to influence the bubble size measurements by McGill bubble viewer include water quality and frother concentration in the chamber.Results show that there is no difference in Sauter mean(D32) when tap or de-ionized water was used instead of process water.However,the frother concentration,in this research DowFroth 250(DF250),inside the chamber exhibited a pronounced effect on bubble size.Frother concentration below a certain point can not prevent coalescence inside the chamber and therefore caution must be taken in plant applications.It was also noted that the frother concentration which has been so far practiced in plant measurements(CCC75-CCC95) is high enough to prevent coalescence with the bubble viewer.
