In order to improve the capillary force of grooved wick, a novel skew-grooved wick structure was proposed for micro heat pipes. Risen meniscus experiments were carried out to research the capillary force of the skew-g...In order to improve the capillary force of grooved wick, a novel skew-grooved wick structure was proposed for micro heat pipes. Risen meniscus experiments were carried out to research the capillary force of the skew-grooved and rectangle-grooved wick and a comparison of capillarity between the two wick structures was explored. A theoretical capillary force model of skew-grooved wick structure was also developed to calculate its effective capillary radius by comparing with the rectangle-grooved wick. From the experimental results, the maximum capillary force of the skewed-grooved wick is 8.62% larger than that of the rectangle-grooved wick. From the theoretical analysis, because the skewed-grooved wick has a smaller effective capillary radius, its maximum capillary force is 8.64% larger than that of the rectangle-grooved wick. The results indicate that the skew-grooved wick provides larger capillary force than the rectangle-grooved wick.展开更多
Development of effective chromatographic or electrophoretic separation involves judicious deciding of selection of optimal experimental conditions that can provide an adequate resolution at a reasonable run time for t...Development of effective chromatographic or electrophoretic separation involves judicious deciding of selection of optimal experimental conditions that can provide an adequate resolution at a reasonable run time for the separation of interested components. Box-Behnken factorial design was effectively applied for the separation optimization of eight structurally related sulfonamides using capillary zone electrophorosis and reverse high performance liquid chromatography. Optimum values for volume ratio of THF to H2O in eluent, column temperature and flow rate of eluent are found as 12 to 88, 35℃ and 1.0 mL/min, respectively. Box-Behnken modified optimization model is extended to separation by capillary electrophoresis (CE). While using CE, a satisfactory separation is achieved with a minimum resolution larger than 1.0 for a separation time less than 10 min.展开更多
Wicking geotextile(WG)is considered as a possible countermeasure to reduce water content in unsaturated soil.In this research,rainfall tests were carried out to verify the drainage performance of WG.And capillary rise...Wicking geotextile(WG)is considered as a possible countermeasure to reduce water content in unsaturated soil.In this research,rainfall tests were carried out to verify the drainage performance of WG.And capillary rise tests were conducted to study the effect of WG on the prevention of capillary rise.Test results indicated that WG with good drainage performance could drain gravitational and capillary water out of kaolinite soil.For kaolinite soil column with water content of 12%and compaction degree of 90%,the whole process of capillary rise in soil column with a layer of WG was a typical two-stage mode,and the maximum capillary height was about 380 mm,which provided that the WG could work as a barrier to prevent capillary rise effectively.In addition,the total vertical influential regions of WG in kaolinite soil above and below the WG layer were 400 and 100 mm,respectively.展开更多
During CO_(2) injection in deep saline aquifers, salt precipitation happens around the injection well because of capillary driven back flow, inducing permeability impairment. The permeability impairment affects CO_(2)...During CO_(2) injection in deep saline aquifers, salt precipitation happens around the injection well because of capillary driven back flow, inducing permeability impairment. The permeability impairment affects CO_(2) injectivity and migration. Different values of three characteristic parameters for capillary pressure function (air entry pressure, empirical parameter m and liquid residual saturation) as well as input absolute value of maximum capillary are chosen in numerical simulation to figure out their effects on salt precipitation. Verma & Pruess model is then used for quantifying permeability impairment. Results show that permeability decreases with higher air entry pressure, larger liquid residual saturation, and especially smaller value of empirical parameter m. To enhance CO_(2) injectivity and avoid blocking of CO_(2) migration, a homogenous formation with large pore size should be chosen before CO_(2) injection into deep saline aquifer.展开更多
Considering two characteristics of compact heat dissipation room and high heat flux, a novel miniature capillary pumped loop (MCPL) for electronics cooling was proposed. MCPL consists of evaporator, condenser, vapor a...Considering two characteristics of compact heat dissipation room and high heat flux, a novel miniature capillary pumped loop (MCPL) for electronics cooling was proposed. MCPL consists of evaporator, condenser, vapor and liquid line dissipates heat by boiling and condensation of working fluids with no extra power consumption. Working fluid circulation is ensured by vapor pressure and capillary head. Saturated wick screens vapor and liquid, and ensures one-way flow of working fluid with no extra valve. In order to promote heat dissipation capacity of MCPL, the intensified boiling and condensation structures are embedded into evaporator and condenser respectively, which are useful to increasing boiling and condensation efficiency. Startup and run characteristics are tested by experiments in the condition of different power inputs and working fluids. MCPL is capable of dissipating 80 W of thermal energy and keeping the bottom substrate temperature of evaporator at 80 ℃.展开更多
Wall slip behavior of three commercial polymer melts polypropylene(iPP),low-density polyethylene(LDPE)(branched chains) and high-density polyethylene(HDPE)(linear chains) were studied by using a capillary rheometer wi...Wall slip behavior of three commercial polymer melts polypropylene(iPP),low-density polyethylene(LDPE)(branched chains) and high-density polyethylene(HDPE)(linear chains) were studied by using a capillary rheometer with twin bores at different temperatures.The results show that a sudden first-stick-then-slip transition was observed for HDPE and a first-slip-then-stick transition was observed for LDPE and iPP as the shear rate sweep was done in an increased order,which shows that the chain structure has an obvious effect on the wall slip behavior of polymers.The critical shear stress for the onset of stick-slip transition increases linearly with temperature for HDPE,which accords with the disentanglement mechanism proposed by Brochard and de Gennes.While the extrapolation length used to quantify the magnitude of the transition remains about 0.05-0.09 mm for HDPE at 150-230 ℃.Also the relationship between the critical shear stress for the onset of wall slip and the molecular mass for polymer samples agrees with the disentanglement model of Brochard and de Gennes.The onset of slip-stick transition for LDPE and iPP at a critical shear stress may be interpreted as the shear thinning of the polymer chains at high shear rates,preventing further development of wall slip behavior.展开更多
The physical process of capillary discharge in a PE tube utilized in electro-thermal-chemical(ETC)guns was investigated.ETC guns can enhance the ignition and combustion of propellant in order to reduce the ignition de...The physical process of capillary discharge in a PE tube utilized in electro-thermal-chemical(ETC)guns was investigated.ETC guns can enhance the ignition and combustion of propellant in order to reduce the ignition delay and increase muzzle velocity of the projectile.A key component in ETC gun is the capillary plasma source.In this paper,a 2D steady state model of discharge was built by using magnetic hydrodynamics method.It took the plasma energy balance,material ablation,mass and momentum conservations in a quasi-neutral plasma region into account.Also,the effect of different compositions and PE concentration distribution were considered.In order to evaluate the validation of this model,the simulation results are compared with former works.展开更多
Strong impact does serious harm to the military industries so it is necessary to choose reasonable cushioning material and design effective buffers to prevent the impact of equipment.Based on the capillary property en...Strong impact does serious harm to the military industries so it is necessary to choose reasonable cushioning material and design effective buffers to prevent the impact of equipment.Based on the capillary property entangled porous metallic wire materials(EPMWM),this paper designed a composite buffer which uses EPMWM and viscous fluid as cushioning materials under the low-speed impact of the recoil force device of weapon equipment(such as artillery,mortar,etc.).Combined with the capillary model,porosity,hydraulic diameter,maximum pore diameter and pore distribution were used to characterize the pore structure characteristics of EPMWM.The calculation model of the damping force of the composite buffer was established.The low-speed impact test of the composite buffer was conducted.The parameters of the buffer under low-speed impact were identified according to the model,and the nonlinear model of damping force was obtained.The test results show that the composite buffer with EPMWM and viscous fluid can absorb the impact energy from the recoil movement effectively,and provide a new method for the buffer design of weapon equipment(such as artillery,mortar,etc.).展开更多
Taking low permeability cores of Daqing oilfield for example,the flow characteristics at low velocity were studied with the self-designed micro-flux measuring instrument.Considering the throat distribution and capilla...Taking low permeability cores of Daqing oilfield for example,the flow characteristics at low velocity were studied with the self-designed micro-flux measuring instrument.Considering the throat distribution and capillary model,the thickness of fluid boundary layer under different pressure gradients was calculated,and the mechanism and influencing factors of nonlinear percolation were discussed.The results show that the percolation curve of ultra-low rocks is nonlinear,and apparent permeability is not a constant which increases with pressure gradient.The absorption boundary layer decreases with the increase of pressure gradient,and changes significantly especially in low pressure gradient,which is the essence of nonlinear percolation.The absorption boundary layer is also found to be impacted by the surface property of rocks.展开更多
An insoluble β-cyclodextrin polymer cross-linked with epichlorohydrin was prepared, and its structure was identified with infrared spectrum. Colloid stationary phase was prepared by dissolving the polymer in the mixe...An insoluble β-cyclodextrin polymer cross-linked with epichlorohydrin was prepared, and its structure was identified with infrared spectrum. Colloid stationary phase was prepared by dissolving the polymer in the mixed solvent of diisopropyl ether, methylene dichloride and benzene and treated for 0.5 h by ultrasonication, and then was coated on a fused silica capillary column. The optimun reaction conditions are as follows: the mole ratio of epichlohydrin to β-cyclodextrin is 12.1:1, reacting at 65 °C for 24 h. The Chromatographic performance such as column efficiency, thermal stabilities and polarity were studied, two kinds of disubstituted benzene isomers and eight pairs of enantiomers were separated on the capillary column. The results show that the β-cyclodextrin polymer is suitable for use as a capillary gas chromatographic stationary phase, and possess excellent chromatographic properties in separating enantiomers and position isomers.展开更多
Two new chiral stationary phases, 2,3 di O acetyl 6 O trimethylsilyl β cyclodextrin (DATBCD) and 2,6 di O trimethylsilyl 3 O acetyl β cyclodextrin(DTABCD), were synthesized, their structures were identified by means...Two new chiral stationary phases, 2,3 di O acetyl 6 O trimethylsilyl β cyclodextrin (DATBCD) and 2,6 di O trimethylsilyl 3 O acetyl β cyclodextrin(DTABCD), were synthesized, their structures were identified by means of infrared and NMR spectra. Capillary columns were coated with the two stationary phases by dynamic method. The chromatographic properties, and enantiomers separation, such as ketone, esters, alcohols and olefines, were investigated on the silylated and acetylated β cyclodextrin stationary phases. The experimental results show that the silylated and acetylated β cyclodextrins are suitable to be used as capillary gas chromatographic stationary phases, the relative polarity of DATBCD and DTABCD stationary phases is respectively 4143 and 3928, the column efficiencies are respectively 3084 and 4198, and DATBCD is of stronger enantioselectivity than DTABCD, capacity factor of the first eluted enantiomer ( k 1) and separation factor(α)of α phenylethanol on DATBCD stationary phase are respectively 8.23 and 1.019.展开更多
In this paper,we present a mathematical model of the cerebrospinal fluid(CSF)formation based on fluid mechanics concepts.Maintenance of intracranial pressure(IP)in the cases of patients with head injury has been a pro...In this paper,we present a mathematical model of the cerebrospinal fluid(CSF)formation based on fluid mechanics concepts.Maintenance of intracranial pressure(IP)in the cases of patients with head injury has been a problem for some time now.Cerebrospinal fluid is one of the cranial vault content that influences the normality of the IP.It was assumed that cerebrospinal fluid(CSF)formation begins as plasma,展开更多
The density of CO<sub>2</sub> inclusions in minerals is commonly used to determine the crystallizing conditions of the host minerals.However,the conventional microthermometry method is difficult to apply f...The density of CO<sub>2</sub> inclusions in minerals is commonly used to determine the crystallizing conditions of the host minerals.However,the conventional microthermometry method is difficult to apply for inclusions that are small in size（【5-10μm） or low in density.Raman analysis is an alternative method for determining CO<sub>2</sub> density,provided that展开更多
基金Project(U0834002) supported by the Key Program of NSFC-Guangdong Joint Funds of ChinaProject(51005079) supported by the National Natural Science Foundation of China+1 种基金Project(2009ZM0121) supported by the Fundamental Research Funds for the Central Universities in ChinaProject(LYM09024) supported by the Training Program for Excellent Young Teachers with Innovation of Guangdong University, China
文摘In order to improve the capillary force of grooved wick, a novel skew-grooved wick structure was proposed for micro heat pipes. Risen meniscus experiments were carried out to research the capillary force of the skew-grooved and rectangle-grooved wick and a comparison of capillarity between the two wick structures was explored. A theoretical capillary force model of skew-grooved wick structure was also developed to calculate its effective capillary radius by comparing with the rectangle-grooved wick. From the experimental results, the maximum capillary force of the skewed-grooved wick is 8.62% larger than that of the rectangle-grooved wick. From the theoretical analysis, because the skewed-grooved wick has a smaller effective capillary radius, its maximum capillary force is 8.64% larger than that of the rectangle-grooved wick. The results indicate that the skew-grooved wick provides larger capillary force than the rectangle-grooved wick.
基金Project(20235010) support by the NSFC-KOSEF Scientific Cooperation ProgramProject supported by the Program for New Century Talents of University in Henan ProvinceProgram for Backbone Teacher in Henan Province, China
文摘Development of effective chromatographic or electrophoretic separation involves judicious deciding of selection of optimal experimental conditions that can provide an adequate resolution at a reasonable run time for the separation of interested components. Box-Behnken factorial design was effectively applied for the separation optimization of eight structurally related sulfonamides using capillary zone electrophorosis and reverse high performance liquid chromatography. Optimum values for volume ratio of THF to H2O in eluent, column temperature and flow rate of eluent are found as 12 to 88, 35℃ and 1.0 mL/min, respectively. Box-Behnken modified optimization model is extended to separation by capillary electrophoresis (CE). While using CE, a satisfactory separation is achieved with a minimum resolution larger than 1.0 for a separation time less than 10 min.
基金Projects(41872240,41672280)supported by the National Natural Science Foundation of ChinaProject(2016-1-16-2)supported by Science and Technology Project of Jilin Province Transportation,ChinaProject(SJCX18-0052)supported by the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China。
文摘Wicking geotextile(WG)is considered as a possible countermeasure to reduce water content in unsaturated soil.In this research,rainfall tests were carried out to verify the drainage performance of WG.And capillary rise tests were conducted to study the effect of WG on the prevention of capillary rise.Test results indicated that WG with good drainage performance could drain gravitational and capillary water out of kaolinite soil.For kaolinite soil column with water content of 12%and compaction degree of 90%,the whole process of capillary rise in soil column with a layer of WG was a typical two-stage mode,and the maximum capillary height was about 380 mm,which provided that the WG could work as a barrier to prevent capillary rise effectively.In addition,the total vertical influential regions of WG in kaolinite soil above and below the WG layer were 400 and 100 mm,respectively.
基金Foundation item:Project(51179060)supported by the National Natural Science Foundation of ChinaProject(20110094130002)supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘During CO_(2) injection in deep saline aquifers, salt precipitation happens around the injection well because of capillary driven back flow, inducing permeability impairment. The permeability impairment affects CO_(2) injectivity and migration. Different values of three characteristic parameters for capillary pressure function (air entry pressure, empirical parameter m and liquid residual saturation) as well as input absolute value of maximum capillary are chosen in numerical simulation to figure out their effects on salt precipitation. Verma & Pruess model is then used for quantifying permeability impairment. Results show that permeability decreases with higher air entry pressure, larger liquid residual saturation, and especially smaller value of empirical parameter m. To enhance CO_(2) injectivity and avoid blocking of CO_(2) migration, a homogenous formation with large pore size should be chosen before CO_(2) injection into deep saline aquifer.
基金Project(50605023) supported by the National Natural Science Foundation of China
文摘Considering two characteristics of compact heat dissipation room and high heat flux, a novel miniature capillary pumped loop (MCPL) for electronics cooling was proposed. MCPL consists of evaporator, condenser, vapor and liquid line dissipates heat by boiling and condensation of working fluids with no extra power consumption. Working fluid circulation is ensured by vapor pressure and capillary head. Saturated wick screens vapor and liquid, and ensures one-way flow of working fluid with no extra valve. In order to promote heat dissipation capacity of MCPL, the intensified boiling and condensation structures are embedded into evaporator and condenser respectively, which are useful to increasing boiling and condensation efficiency. Startup and run characteristics are tested by experiments in the condition of different power inputs and working fluids. MCPL is capable of dissipating 80 W of thermal energy and keeping the bottom substrate temperature of evaporator at 80 ℃.
基金Projects(ZMF07020038) supported by the Young Teacher's Scientific Research Fund of Jiangsu Polytechnic University,China
文摘Wall slip behavior of three commercial polymer melts polypropylene(iPP),low-density polyethylene(LDPE)(branched chains) and high-density polyethylene(HDPE)(linear chains) were studied by using a capillary rheometer with twin bores at different temperatures.The results show that a sudden first-stick-then-slip transition was observed for HDPE and a first-slip-then-stick transition was observed for LDPE and iPP as the shear rate sweep was done in an increased order,which shows that the chain structure has an obvious effect on the wall slip behavior of polymers.The critical shear stress for the onset of stick-slip transition increases linearly with temperature for HDPE,which accords with the disentanglement mechanism proposed by Brochard and de Gennes.While the extrapolation length used to quantify the magnitude of the transition remains about 0.05-0.09 mm for HDPE at 150-230 ℃.Also the relationship between the critical shear stress for the onset of wall slip and the molecular mass for polymer samples agrees with the disentanglement model of Brochard and de Gennes.The onset of slip-stick transition for LDPE and iPP at a critical shear stress may be interpreted as the shear thinning of the polymer chains at high shear rates,preventing further development of wall slip behavior.
文摘The physical process of capillary discharge in a PE tube utilized in electro-thermal-chemical(ETC)guns was investigated.ETC guns can enhance the ignition and combustion of propellant in order to reduce the ignition delay and increase muzzle velocity of the projectile.A key component in ETC gun is the capillary plasma source.In this paper,a 2D steady state model of discharge was built by using magnetic hydrodynamics method.It took the plasma energy balance,material ablation,mass and momentum conservations in a quasi-neutral plasma region into account.Also,the effect of different compositions and PE concentration distribution were considered.In order to evaluate the validation of this model,the simulation results are compared with former works.
基金supported by the National Natural Science Foundation of China (Grant No.51805086)。
文摘Strong impact does serious harm to the military industries so it is necessary to choose reasonable cushioning material and design effective buffers to prevent the impact of equipment.Based on the capillary property entangled porous metallic wire materials(EPMWM),this paper designed a composite buffer which uses EPMWM and viscous fluid as cushioning materials under the low-speed impact of the recoil force device of weapon equipment(such as artillery,mortar,etc.).Combined with the capillary model,porosity,hydraulic diameter,maximum pore diameter and pore distribution were used to characterize the pore structure characteristics of EPMWM.The calculation model of the damping force of the composite buffer was established.The low-speed impact test of the composite buffer was conducted.The parameters of the buffer under low-speed impact were identified according to the model,and the nonlinear model of damping force was obtained.The test results show that the composite buffer with EPMWM and viscous fluid can absorb the impact energy from the recoil movement effectively,and provide a new method for the buffer design of weapon equipment(such as artillery,mortar,etc.).
基金Project(2008ZX05013) supported by the National Science and Technology Project of ChinaProject(10672187) supported by the National Natural Science Foundation of China
文摘Taking low permeability cores of Daqing oilfield for example,the flow characteristics at low velocity were studied with the self-designed micro-flux measuring instrument.Considering the throat distribution and capillary model,the thickness of fluid boundary layer under different pressure gradients was calculated,and the mechanism and influencing factors of nonlinear percolation were discussed.The results show that the percolation curve of ultra-low rocks is nonlinear,and apparent permeability is not a constant which increases with pressure gradient.The absorption boundary layer decreases with the increase of pressure gradient,and changes significantly especially in low pressure gradient,which is the essence of nonlinear percolation.The absorption boundary layer is also found to be impacted by the surface property of rocks.
文摘An insoluble β-cyclodextrin polymer cross-linked with epichlorohydrin was prepared, and its structure was identified with infrared spectrum. Colloid stationary phase was prepared by dissolving the polymer in the mixed solvent of diisopropyl ether, methylene dichloride and benzene and treated for 0.5 h by ultrasonication, and then was coated on a fused silica capillary column. The optimun reaction conditions are as follows: the mole ratio of epichlohydrin to β-cyclodextrin is 12.1:1, reacting at 65 °C for 24 h. The Chromatographic performance such as column efficiency, thermal stabilities and polarity were studied, two kinds of disubstituted benzene isomers and eight pairs of enantiomers were separated on the capillary column. The results show that the β-cyclodextrin polymer is suitable for use as a capillary gas chromatographic stationary phase, and possess excellent chromatographic properties in separating enantiomers and position isomers.
文摘Two new chiral stationary phases, 2,3 di O acetyl 6 O trimethylsilyl β cyclodextrin (DATBCD) and 2,6 di O trimethylsilyl 3 O acetyl β cyclodextrin(DTABCD), were synthesized, their structures were identified by means of infrared and NMR spectra. Capillary columns were coated with the two stationary phases by dynamic method. The chromatographic properties, and enantiomers separation, such as ketone, esters, alcohols and olefines, were investigated on the silylated and acetylated β cyclodextrin stationary phases. The experimental results show that the silylated and acetylated β cyclodextrins are suitable to be used as capillary gas chromatographic stationary phases, the relative polarity of DATBCD and DTABCD stationary phases is respectively 4143 and 3928, the column efficiencies are respectively 3084 and 4198, and DATBCD is of stronger enantioselectivity than DTABCD, capacity factor of the first eluted enantiomer ( k 1) and separation factor(α)of α phenylethanol on DATBCD stationary phase are respectively 8.23 and 1.019.
文摘In this paper,we present a mathematical model of the cerebrospinal fluid(CSF)formation based on fluid mechanics concepts.Maintenance of intracranial pressure(IP)in the cases of patients with head injury has been a problem for some time now.Cerebrospinal fluid is one of the cranial vault content that influences the normality of the IP.It was assumed that cerebrospinal fluid(CSF)formation begins as plasma,
文摘The density of CO<sub>2</sub> inclusions in minerals is commonly used to determine the crystallizing conditions of the host minerals.However,the conventional microthermometry method is difficult to apply for inclusions that are small in size（【5-10μm） or low in density.Raman analysis is an alternative method for determining CO<sub>2</sub> density,provided that
