The coupled effect of viscosity enhancing admixtures(VEA)and superplasticizer(SP)on the rheological behavior of cement paste was investigated in this work.Two types of VEAs,including hydroxypropyl methylcellulose(HPMC...The coupled effect of viscosity enhancing admixtures(VEA)and superplasticizer(SP)on the rheological behavior of cement paste was investigated in this work.Two types of VEAs,including hydroxypropyl methylcellulose(HPMC)and Welan gum,and two types of SPs,i.e.polycarboxylate(PCA)and polynaphthalenesulfonate(PNS)were used as admixtures for cement paste.Rheological curves of cement paste and simulated pore solution containing VEA and SP were tested.Simulated pore solution test results show that molecules of different SPs may generate different effects on the viscosity of VEA solutions.Hershel-Bulkley(H-B)model was used to fit rheological curve of cement paste.Strong interaction between PNS and HPMC was observed in this work.展开更多
Poly-L-lactide（PLLA） was synthesized by ring-opening polymerization fi＇om high purity L-lactide with tin octoate as initiator, and characterized by means of infi＇ared, and ^1H-nuclear magnetic resonance. The influ...Poly-L-lactide（PLLA） was synthesized by ring-opening polymerization fi＇om high purity L-lactide with tin octoate as initiator, and characterized by means of infi＇ared, and ^1H-nuclear magnetic resonance. The influences of initiator concentration, polymerization temperature and polymerization time on the viscosity average molecular mass of PLLA were investigated. The effects of different purification methods on the concentration of initiator and viscosity average molecular mass were also studied. PLLA with a viscosity average molecular mass of about 50.5×1^04 was obtained when polymerization was conducted for 24 h at 140℃ with the molar ratio of monomer to purification initator being 12 000. After purification, the concentration of tin octoate decreases; however, the effect of different purification methods on the viscosity average molecular mass of PLLA is different, and the obtained PLLA is a typical amorphous polymeric material. The crystallinity of PLLA decreases with the increase of viscosity average molecular mass.展开更多
The effect of sulfide on HPAM solution viscosity was studied using BROOKFIELD DV-II viscometer,and the interaction mechanism was discussed.The HPAM solution viscosity was investigated through fully reducing sulfide by...The effect of sulfide on HPAM solution viscosity was studied using BROOKFIELD DV-II viscometer,and the interaction mechanism was discussed.The HPAM solution viscosity was investigated through fully reducing sulfide by the addition of hydrogen peroxide oxidation,and the mechanism of increasing polymer viscosity was investigated.The experimental results also show that there is a critical concentration of 15 mg/L.Below it,the loss rate of HPAM solution viscosity increases more rapidly,but becomes slowly above the critical concentration.A theoretical guidance for oilfields to prepare polymer solution using sewage-water by eliminating sulfide,and it is also importance to prepare polymer solution using sewage-water and save fresh water.展开更多
High-viscosity dispersing system is formed by dispersing the solid particles in the high-viscosity continuous medium.It is very easy to form the three-dimensional network structure for solid particles in the system an...High-viscosity dispersing system is formed by dispersing the solid particles in the high-viscosity continuous medium.It is very easy to form the three-dimensional network structure for solid particles in the system and the rheology behavior becomes complicated.The apparent viscosity of this dispersing system always has the connection with the volume ratio and the shear rate.In order to discuss the rheology behavior and put up the viscosity model,the suspension of silicon dioxide and silicon oil were prepared.Through testing the viscosity,the solid concentration and the shear rate,the effects of the ratio and the shear rate on viscosity was analyzed,the model of the high-viscosity dispersing system was designed and the model with the printing ink were validated.The experiment results show that the model is applicable to the high-viscosity dispersing systems.展开更多
A further numerical study of the theory that the drag reduction in the turbulence is related to the viscosity profile growing linearly with the distance from the wall was performed.The constant viscosity in the Navier...A further numerical study of the theory that the drag reduction in the turbulence is related to the viscosity profile growing linearly with the distance from the wall was performed.The constant viscosity in the Navier-Stokes equations was replaced using this viscosity model.Some drag reduction characteristics were shown comparing with Virk's phenomenology.The mean velocity and Reynolds stress profiles are consistent with the experimental and direct numerical simulation results.A drag reduction level of 45% was obtained.It is reasonable for this linear viscosity model to explain the mechanism of turbulence drag reduction in some aspects.展开更多
The dynamic analysis of semi-flexible polymers,such as DNA molecules,is an important multiscale problem with a wide range of applications in science and bioengineering.In this contribution,a dumbbell model with intern...The dynamic analysis of semi-flexible polymers,such as DNA molecules,is an important multiscale problem with a wide range of applications in science and bioengineering.In this contribution,a dumbbell model with internal viscosity was studied in steady shear flows of polymeric fluid.The tensors with moments other than second moment were approximated in the terms of second moment tensor.Then,the nonlinear algebraic equation of the second moment conformation tensor was calculated in closed form.Finally,substituting the resulting conformation tensor into the Kramers equation of Hookean spring force,the constitutive equations were obtained.The shear material properties were discussed for different internal viscosities and compared with the results of Brownian dynamics simulation.展开更多
The effect of temperature and metal ion components on the viscosity of HPAM solution was studied by means of orthogonal method.Five factors and 4 levels were considered for the orthogonal design.The five factors inclu...The effect of temperature and metal ion components on the viscosity of HPAM solution was studied by means of orthogonal method.Five factors and 4 levels were considered for the orthogonal design.The five factors included temperature,contents of Na+,Mg2+,Ca2+ and S2-,and the four levels mainly considered the level of produced water components in main oilfields in China.The experiment results show that temperature is the most important factor to control HPAM solution viscosity prepared by produced water.The effect of ions was in order of Na+>S2->Mg2+>Ca2+.The mechanism of each factor influencing viscosity was also discussed.Based on the actual condition of Nanyang oilfield,the desulfurization was used to improve the solution viscosity,and satisfactory result was obtained.展开更多
A series of experiments were performed on the viscosity of a nanofluid,produced by mixing carbon black and mulsifier OP-10 using ammonia-water with the ultrasonic dispersion.The results show that,when adding surfactan...A series of experiments were performed on the viscosity of a nanofluid,produced by mixing carbon black and mulsifier OP-10 using ammonia-water with the ultrasonic dispersion.The results show that,when adding surfactant separately in low mass concentrations,at first the viscosity of solution decreases sharply compared with that of ammonia-water,then increases with increasing the concentration of OP-10.In a certain concentration of surfactant,the viscosity of nanofluids increases with increasing the concentration of nanoparticles.Based on Einstein model and Langmuir absorption theory,a new model was summed up for nanofluids.Compared with test values,the calculated values on the new model have verified that the model is suitable to predict the viscosity of nanofluids,because the maximum relative error is less than 5%.Nano-particles absorption in the nanofluids is not only single-molecule layer adsorption,but also multi-layer molecular adsorption and other complicated adsorption.So the new model,only based on single-molecule layer adsorption theory of Langmuir,is not fully in line with the real circumstances.展开更多
Protein folding involves the aminoacid sequence to come forth and form an energy minimized structure.Recently molecular crowding leading to increase in viscosity is said to be one of the major concerns affecting prote...Protein folding involves the aminoacid sequence to come forth and form an energy minimized structure.Recently molecular crowding leading to increase in viscosity is said to be one of the major concerns affecting protein folding.Many external fluorescent probes are used to detect such increases in viscosity.Since most of the protein sequences contain L-Phe and L-Trp,in this study we have used these aminoacids as probes to detect changes in viscosity.This study will help to advance the knowledge on molecular crowding effects in protein folding.展开更多
The biological variety is mainly connected with presence of the field ecosites,which determine the mechanism of interaction(the symbiosis,pathogenesis,and etc.) that differ typically of such
The high-carbon ferrochrome is an essential raw material for producing stainless steel,and the demand of it increases with the increase of stainless steel.So increasing Cr recovery rate from chromite is essential for ...The high-carbon ferrochrome is an essential raw material for producing stainless steel,and the demand of it increases with the increase of stainless steel.So increasing Cr recovery rate from chromite is essential for lower costs and higher economic benefits in high-carbon ferrochrome production process.This study calculated the activity of CrO_(x)in slag and investigated the distribution behavior of Cr between slag and alloy.Theω(MgO)/ω(Al_(2)O_(3))was 1.0,and the w(CaO)/w(SiO_(2))was from 0.2 to 0.6 in this study.The calculation and experimental results showed that the main phases of the slag were chrome-containing spinel,magnesium-aluminum spinel,olivine and melilite.The content of spinel in slag decreased with the increasing w(CaO)/w(SiO_(2)),and the w(CrO_(x))in spinel also reduced,but the content of melilite increased.The distribution ratio of Cr between slag and alloy decreased with the increase of slag basicity at 1600℃,meansning that increasing the w(CaO)/w(SiO_(2))of slag can improve the recovery of Cr in chromite smelting process.展开更多
The high-flowing sand-concrete （HFSC） containing natural sands as aggregate was carried out. The high fluidity and stability of HFSC can be achieved by tailoring the mix design parameters, such as fine to coarse san...The high-flowing sand-concrete （HFSC） containing natural sands as aggregate was carried out. The high fluidity and stability of HFSC can be achieved by tailoring the mix design parameters, such as fine to coarse sand ratio, dosage of additions, water to binder ratio and dosage of admixtures. Mini-cone slump test, v-fl.mnel time test and viscosity model parameters were used to characterize the behaviour of HFSC in fresh state. The mechanical compressive strength in 28 d was also determined. A factorial design approach was used to establish models highlighting the effect of each mix-parameter on measured properties of HFSC. The derived models are valid for mixtures made with 0 to 0.3 of dune sand to total sand ratio, 82 to 418 kg/m3 of marble powder, 0.42 to 0.46 of water/binder ratio and 1.3% to 1.9% of superplasticizer high water-reducer. The results show that the derived models constitute very efficient means for understanding the influence of key mix-parameters on HFSC properties and are useful in selecting the optimum mix proportions, by simulating their impact on fluidity, stability and compressive strength.展开更多
The influence of different features of natural soft clays,namely anisotropy,destructuration and viscosity,on modelling the time-dependent behaviour of Murro embankment was investigated.The newly developed elasto-visco...The influence of different features of natural soft clays,namely anisotropy,destructuration and viscosity,on modelling the time-dependent behaviour of Murro embankment was investigated.The newly developed elasto-viscoplastic models were enhanced for determining viscosity parameters in a straightforward way and adopted for the finite element analysis.The same set of common parameters determined from conventional triaxial and oedometer tests was employed for all models,with additional parameters required for representing different soil features.The finite element predictions by using models coupled with BIOT's consolidation theory were compared with each other and with field data for settlement,horizontal displacement and excess pore pressures.In addition,the stress paths under the embankment loading were also compared with each other to improve the understanding of the effect of different soil features.All simulations demonstrate that all three features significantly influence the predictions.As a consequence,accounting for soil features needs to be carefully considered when they are applied to a construction site.展开更多
In order to optimize plastic viscosity of 18 mPa·s circulating micro-bubble drilling fluid formula,orthogonal and uniform experimental design methods were applied,and the plastic viscosities of 36 and 24 groups o...In order to optimize plastic viscosity of 18 mPa·s circulating micro-bubble drilling fluid formula,orthogonal and uniform experimental design methods were applied,and the plastic viscosities of 36 and 24 groups of agent were tested,respectively.It is found that these two experimental design methods show drawbacks,that is,the amount of agent is difficult to determine,and the results are not fully optimized.Therefore,multiple regression experimental method was used to design experimental formula.By randomly selecting arbitrary agent with the amount within the recommended range,17 groups of drilling fluid formula were designed,and the plastic viscosity of each experiment formula was measured.Set plastic viscosity as the objective function,through multiple regressions,then quadratic regression model is obtained,whose correlation coefficient meets the requirement.Set target values of plastic viscosity to be 18,20 and 22 mPa·s,respectively,with the trial method,5 drilling fluid formulas are obtained with accuracy of 0.000 3,0.000 1 and 0.000 3.Arbitrarily select target value of each of the two groups under the formula for experimental verification of drilling fluid,then the measurement errors between theoretical and tested plastic viscosity are less than 5%,confirming that regression model can be applied to optimizing the circulating of plastic-foam drilling fluid viscosity.In accordance with the precision of different formulations of drilling fluid for other constraints,the methods result in the optimization of the circulating micro-bubble drilling fluid parameters.展开更多
Rheological properties of low-concentration Konjac gum and impacts of concentration,shearing rate,pH value and stirring time on its viscosity were studied.The results show that the viscosity of low-concentration Konja...Rheological properties of low-concentration Konjac gum and impacts of concentration,shearing rate,pH value and stirring time on its viscosity were studied.The results show that the viscosity of low-concentration Konjac gum increases with the increase of its concentration.The solution presents pseudo-plasticity fluid,which shows the characters of shear thinning as follows:first,its viscosity decreases gradually as the temperature increases,and then increases with the increase of temperature.The viscosity decreases sharply at both acid and alkaline conditions,indicating that it is influenced apparently by pH value.And the viscosity of low-concentration Konjac gum is also impacted by the stirring time.展开更多
The specific results of the work investigating the effect of gas density and water temperature on bubble size were present.These were surrogate variables designed to investigate the effect of viscosity(varying water t...The specific results of the work investigating the effect of gas density and water temperature on bubble size were present.These were surrogate variables designed to investigate the effect of viscosity(varying water temperature) and altitude(varying gas density).The results show that there is a measurable but relatively small effect of gas density on bubble size.The D32 is revealed to increase proportionally as(ρ0/ρg)0.132.The projected impact on flotation kinetics at 4500 m versus sea level is small,of the order of 0.5% recovery loss for a bank of eight flotation cells.The effect of water temperature(4-40 °C) on bubble size is more significant than gas density.The relationship correlates with water viscosity values quite closely.A finding that D32 increases proportionally as(μ/μ20)0.776 highlights the importance of accounting for viscosity effects if,for example,large process temperature fluctuations or deviation from design/test conditions are expected.展开更多
In order to correctly predict tube cross section time-smoothed velocity distribution, friction factor and mass transfer behavior, two models for turbulent flow in circular tubes based on classical Prandtl mixing lengt...In order to correctly predict tube cross section time-smoothed velocity distribution, friction factor and mass transfer behavior, two models for turbulent flow in circular tubes based on classical Prandtl mixing length theory and a modified mixing length were established. The results show that the modified mixing length includes the introduction of a damping function for the viscous sublayer and the second-order derivative to approximate eddy velocity. The calculated dimensionless time-smoothed velocity from the model based on Prandtl mixing length is much better than the result from the concept of eddy viscosity. The calculated eddy viscosity from the model based on modified mixing length is much better than the result from the model based on the classical Prandtl mixing length theory. And the friction factor calculated from the model based on the modified mixing length agrees well with the reported empirical relationships.展开更多
The rapeseed oil extracted from the mature seeds was purified by refining processing,and the rheological characteristic analysis of the viscosity and dynamic shear rate at gradient temperatures was made.The result sho...The rapeseed oil extracted from the mature seeds was purified by refining processing,and the rheological characteristic analysis of the viscosity and dynamic shear rate at gradient temperatures was made.The result shows that at 20,40,60 and 80 ℃ respectively,when the shear rate gradually rises,the torque increases accordingly but its viscosity does not vary distinctly.The result suggests that when rapeseed oil is used as the raw of edible oils and industries,the working procedures at high temperature will not influence its rheological characteristic distinctly.展开更多
基金Project(2017YFB0310101)supported by National High Technology Research and Development Program of ChinaProject(51778269)supported by the National Natural Science Foundation of China
文摘The coupled effect of viscosity enhancing admixtures(VEA)and superplasticizer(SP)on the rheological behavior of cement paste was investigated in this work.Two types of VEAs,including hydroxypropyl methylcellulose(HPMC)and Welan gum,and two types of SPs,i.e.polycarboxylate(PCA)and polynaphthalenesulfonate(PNS)were used as admixtures for cement paste.Rheological curves of cement paste and simulated pore solution containing VEA and SP were tested.Simulated pore solution test results show that molecules of different SPs may generate different effects on the viscosity of VEA solutions.Hershel-Bulkley(H-B)model was used to fit rheological curve of cement paste.Strong interaction between PNS and HPMC was observed in this work.
基金Project (50174059) supported by the National Natural Science Foundation of China
文摘Poly-L-lactide（PLLA） was synthesized by ring-opening polymerization fi＇om high purity L-lactide with tin octoate as initiator, and characterized by means of infi＇ared, and ^1H-nuclear magnetic resonance. The influences of initiator concentration, polymerization temperature and polymerization time on the viscosity average molecular mass of PLLA were investigated. The effects of different purification methods on the concentration of initiator and viscosity average molecular mass were also studied. PLLA with a viscosity average molecular mass of about 50.5×1^04 was obtained when polymerization was conducted for 24 h at 140℃ with the molar ratio of monomer to purification initator being 12 000. After purification, the concentration of tin octoate decreases; however, the effect of different purification methods on the viscosity average molecular mass of PLLA is different, and the obtained PLLA is a typical amorphous polymeric material. The crystallinity of PLLA decreases with the increase of viscosity average molecular mass.
基金Project(200873181) supported by NSFCProject(2007AA06Z214) supported by the High-tech Research and Development Program of ChinaProject(20070704) supported by Taishan Scholars Construction Engineering
文摘The effect of sulfide on HPAM solution viscosity was studied using BROOKFIELD DV-II viscometer,and the interaction mechanism was discussed.The HPAM solution viscosity was investigated through fully reducing sulfide by the addition of hydrogen peroxide oxidation,and the mechanism of increasing polymer viscosity was investigated.The experimental results also show that there is a critical concentration of 15 mg/L.Below it,the loss rate of HPAM solution viscosity increases more rapidly,but becomes slowly above the critical concentration.A theoretical guidance for oilfields to prepare polymer solution using sewage-water by eliminating sulfide,and it is also importance to prepare polymer solution using sewage-water and save fresh water.
文摘High-viscosity dispersing system is formed by dispersing the solid particles in the high-viscosity continuous medium.It is very easy to form the three-dimensional network structure for solid particles in the system and the rheology behavior becomes complicated.The apparent viscosity of this dispersing system always has the connection with the volume ratio and the shear rate.In order to discuss the rheology behavior and put up the viscosity model,the suspension of silicon dioxide and silicon oil were prepared.Through testing the viscosity,the solid concentration and the shear rate,the effects of the ratio and the shear rate on viscosity was analyzed,the model of the high-viscosity dispersing system was designed and the model with the printing ink were validated.The experiment results show that the model is applicable to the high-viscosity dispersing systems.
基金Project(10672069) supported by the National Natural Science Foundation of China
文摘A further numerical study of the theory that the drag reduction in the turbulence is related to the viscosity profile growing linearly with the distance from the wall was performed.The constant viscosity in the Navier-Stokes equations was replaced using this viscosity model.Some drag reduction characteristics were shown comparing with Virk's phenomenology.The mean velocity and Reynolds stress profiles are consistent with the experimental and direct numerical simulation results.A drag reduction level of 45% was obtained.It is reasonable for this linear viscosity model to explain the mechanism of turbulence drag reduction in some aspects.
基金Project(10702045) supported by the National Natural Science Foundation of China
文摘The dynamic analysis of semi-flexible polymers,such as DNA molecules,is an important multiscale problem with a wide range of applications in science and bioengineering.In this contribution,a dumbbell model with internal viscosity was studied in steady shear flows of polymeric fluid.The tensors with moments other than second moment were approximated in the terms of second moment tensor.Then,the nonlinear algebraic equation of the second moment conformation tensor was calculated in closed form.Finally,substituting the resulting conformation tensor into the Kramers equation of Hookean spring force,the constitutive equations were obtained.The shear material properties were discussed for different internal viscosities and compared with the results of Brownian dynamics simulation.
基金Project(2007AA06Z214) supported by the National High-Tech Research and Development Program of ChinaProject(ts20070704) supported by Taishan Scholars Construction EngineeringProject(200873181) supported by National Natural Science Foundation of China
文摘The effect of temperature and metal ion components on the viscosity of HPAM solution was studied by means of orthogonal method.Five factors and 4 levels were considered for the orthogonal design.The five factors included temperature,contents of Na+,Mg2+,Ca2+ and S2-,and the four levels mainly considered the level of produced water components in main oilfields in China.The experiment results show that temperature is the most important factor to control HPAM solution viscosity prepared by produced water.The effect of ions was in order of Na+>S2->Mg2+>Ca2+.The mechanism of each factor influencing viscosity was also discussed.Based on the actual condition of Nanyang oilfield,the desulfurization was used to improve the solution viscosity,and satisfactory result was obtained.
基金Supported by National Natural Science Foundation of China(50876020)
文摘A series of experiments were performed on the viscosity of a nanofluid,produced by mixing carbon black and mulsifier OP-10 using ammonia-water with the ultrasonic dispersion.The results show that,when adding surfactant separately in low mass concentrations,at first the viscosity of solution decreases sharply compared with that of ammonia-water,then increases with increasing the concentration of OP-10.In a certain concentration of surfactant,the viscosity of nanofluids increases with increasing the concentration of nanoparticles.Based on Einstein model and Langmuir absorption theory,a new model was summed up for nanofluids.Compared with test values,the calculated values on the new model have verified that the model is suitable to predict the viscosity of nanofluids,because the maximum relative error is less than 5%.Nano-particles absorption in the nanofluids is not only single-molecule layer adsorption,but also multi-layer molecular adsorption and other complicated adsorption.So the new model,only based on single-molecule layer adsorption theory of Langmuir,is not fully in line with the real circumstances.
文摘Protein folding involves the aminoacid sequence to come forth and form an energy minimized structure.Recently molecular crowding leading to increase in viscosity is said to be one of the major concerns affecting protein folding.Many external fluorescent probes are used to detect such increases in viscosity.Since most of the protein sequences contain L-Phe and L-Trp,in this study we have used these aminoacids as probes to detect changes in viscosity.This study will help to advance the knowledge on molecular crowding effects in protein folding.
文摘The biological variety is mainly connected with presence of the field ecosites,which determine the mechanism of interaction(the symbiosis,pathogenesis,and etc.) that differ typically of such
基金Project(2023XQLH055)supported by Central South University Graduate Research Innovation Project(University-Enterprise Joint Project),China。
文摘The high-carbon ferrochrome is an essential raw material for producing stainless steel,and the demand of it increases with the increase of stainless steel.So increasing Cr recovery rate from chromite is essential for lower costs and higher economic benefits in high-carbon ferrochrome production process.This study calculated the activity of CrO_(x)in slag and investigated the distribution behavior of Cr between slag and alloy.Theω(MgO)/ω(Al_(2)O_(3))was 1.0,and the w(CaO)/w(SiO_(2))was from 0.2 to 0.6 in this study.The calculation and experimental results showed that the main phases of the slag were chrome-containing spinel,magnesium-aluminum spinel,olivine and melilite.The content of spinel in slag decreased with the increasing w(CaO)/w(SiO_(2)),and the w(CrO_(x))in spinel also reduced,but the content of melilite increased.The distribution ratio of Cr between slag and alloy decreased with the increase of slag basicity at 1600℃,meansning that increasing the w(CaO)/w(SiO_(2))of slag can improve the recovery of Cr in chromite smelting process.
文摘The high-flowing sand-concrete （HFSC） containing natural sands as aggregate was carried out. The high fluidity and stability of HFSC can be achieved by tailoring the mix design parameters, such as fine to coarse sand ratio, dosage of additions, water to binder ratio and dosage of admixtures. Mini-cone slump test, v-fl.mnel time test and viscosity model parameters were used to characterize the behaviour of HFSC in fresh state. The mechanical compressive strength in 28 d was also determined. A factorial design approach was used to establish models highlighting the effect of each mix-parameter on measured properties of HFSC. The derived models are valid for mixtures made with 0 to 0.3 of dune sand to total sand ratio, 82 to 418 kg/m3 of marble powder, 0.42 to 0.46 of water/binder ratio and 1.3% to 1.9% of superplasticizer high water-reducer. The results show that the derived models constitute very efficient means for understanding the influence of key mix-parameters on HFSC properties and are useful in selecting the optimum mix proportions, by simulating their impact on fluidity, stability and compressive strength.
基金Project(11PJ1405700) supported by Pujiang Talent Plan of Shanghai,ChinaProject(41002091) supported by the National Natural Science Foundation of ChinaProject(PIAP-GA-2009-230638) supported by the European Community through the Program "People"
文摘The influence of different features of natural soft clays,namely anisotropy,destructuration and viscosity,on modelling the time-dependent behaviour of Murro embankment was investigated.The newly developed elasto-viscoplastic models were enhanced for determining viscosity parameters in a straightforward way and adopted for the finite element analysis.The same set of common parameters determined from conventional triaxial and oedometer tests was employed for all models,with additional parameters required for representing different soil features.The finite element predictions by using models coupled with BIOT's consolidation theory were compared with each other and with field data for settlement,horizontal displacement and excess pore pressures.In addition,the stress paths under the embankment loading were also compared with each other to improve the understanding of the effect of different soil features.All simulations demonstrate that all three features significantly influence the predictions.As a consequence,accounting for soil features needs to be carefully considered when they are applied to a construction site.
基金Project(50304010) supported by the National Natural Science Foundation of China
文摘In order to optimize plastic viscosity of 18 mPa·s circulating micro-bubble drilling fluid formula,orthogonal and uniform experimental design methods were applied,and the plastic viscosities of 36 and 24 groups of agent were tested,respectively.It is found that these two experimental design methods show drawbacks,that is,the amount of agent is difficult to determine,and the results are not fully optimized.Therefore,multiple regression experimental method was used to design experimental formula.By randomly selecting arbitrary agent with the amount within the recommended range,17 groups of drilling fluid formula were designed,and the plastic viscosity of each experiment formula was measured.Set plastic viscosity as the objective function,through multiple regressions,then quadratic regression model is obtained,whose correlation coefficient meets the requirement.Set target values of plastic viscosity to be 18,20 and 22 mPa·s,respectively,with the trial method,5 drilling fluid formulas are obtained with accuracy of 0.000 3,0.000 1 and 0.000 3.Arbitrarily select target value of each of the two groups under the formula for experimental verification of drilling fluid,then the measurement errors between theoretical and tested plastic viscosity are less than 5%,confirming that regression model can be applied to optimizing the circulating of plastic-foam drilling fluid viscosity.In accordance with the precision of different formulations of drilling fluid for other constraints,the methods result in the optimization of the circulating micro-bubble drilling fluid parameters.
基金Project(08RM05) supported by Institute of Rheological Mechanics and Material Engineering of Central South University of Forestry Technology
文摘Rheological properties of low-concentration Konjac gum and impacts of concentration,shearing rate,pH value and stirring time on its viscosity were studied.The results show that the viscosity of low-concentration Konjac gum increases with the increase of its concentration.The solution presents pseudo-plasticity fluid,which shows the characters of shear thinning as follows:first,its viscosity decreases gradually as the temperature increases,and then increases with the increase of temperature.The viscosity decreases sharply at both acid and alkaline conditions,indicating that it is influenced apparently by pH value.And the viscosity of low-concentration Konjac gum is also impacted by the stirring time.
基金Project supported by 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The specific results of the work investigating the effect of gas density and water temperature on bubble size were present.These were surrogate variables designed to investigate the effect of viscosity(varying water temperature) and altitude(varying gas density).The results show that there is a measurable but relatively small effect of gas density on bubble size.The D32 is revealed to increase proportionally as(ρ0/ρg)0.132.The projected impact on flotation kinetics at 4500 m versus sea level is small,of the order of 0.5% recovery loss for a bank of eight flotation cells.The effect of water temperature(4-40 °C) on bubble size is more significant than gas density.The relationship correlates with water viscosity values quite closely.A finding that D32 increases proportionally as(μ/μ20)0.776 highlights the importance of accounting for viscosity effects if,for example,large process temperature fluctuations or deviation from design/test conditions are expected.
基金Project(20736009) supported by the National Natural Science Foundation of ChinaProject(07JJ6017) supported by the Natural Science Foundation of Hunan Province, China
文摘In order to correctly predict tube cross section time-smoothed velocity distribution, friction factor and mass transfer behavior, two models for turbulent flow in circular tubes based on classical Prandtl mixing length theory and a modified mixing length were established. The results show that the modified mixing length includes the introduction of a damping function for the viscous sublayer and the second-order derivative to approximate eddy velocity. The calculated dimensionless time-smoothed velocity from the model based on Prandtl mixing length is much better than the result from the concept of eddy viscosity. The calculated eddy viscosity from the model based on modified mixing length is much better than the result from the model based on the classical Prandtl mixing length theory. And the friction factor calculated from the model based on the modified mixing length agrees well with the reported empirical relationships.
基金Project(2007CB210201) supported by Major State Basic Research Development Program of ChinaProject(07JJ6053) supported by Hunan Provincial Natural Science Foundation of China
文摘The rapeseed oil extracted from the mature seeds was purified by refining processing,and the rheological characteristic analysis of the viscosity and dynamic shear rate at gradient temperatures was made.The result shows that at 20,40,60 and 80 ℃ respectively,when the shear rate gradually rises,the torque increases accordingly but its viscosity does not vary distinctly.The result suggests that when rapeseed oil is used as the raw of edible oils and industries,the working procedures at high temperature will not influence its rheological characteristic distinctly.
