Geothermal energy is a clean and ecologically friendly energy source with significant potential. The temperature variations between the Polycrystalline Diamond Compact (PDC) cutter and the rock of the reservoir are th...Geothermal energy is a clean and ecologically friendly energy source with significant potential. The temperature variations between the Polycrystalline Diamond Compact (PDC) cutter and the rock of the reservoir are the key factors affecting the cutting performance when drilling through formations with thermally damaged rock. To better investigate the temperature rise, a series of rock samples treated at high temperatures (9–300℃) were broken with a PDC cutter. The performance of the PDC cutter on these samples was studied using cutting force sensors, high-speed photography, and the thermal infrared imager. Based on the experimental data, a new cutting force evaluation parameter, η, is suggested. The link between the cutting force and rock properties is discussed in detail. The present results indicate that the average cutting force of high-temperature-treated granite is 3–5 times that of the thermally damaged sandstone. Furthermore, a critical temperature for thermal damage has been identified in granite cutting at 100–200℃ and in sandstone at 100℃. This corresponds to the temperature at which interlayer water loss and thermal crack closure occur. The results also indicate that when the treatment temperature exceeds the critical threshold, both the cutting force and temperature rise exhibit more significant changes with increasing temperature. Additionally, the maximum temperature of the PDC cutter during granite cutting can reach 47.6 ℃, which is almost 34℃ higher than that of sandstone. Regarding debris size, granite is much less sensitive to the treatment temperature, showing only slight changes in debris size compared to sandstone as the treatment temperature increases. The increasing cutter-rock interface area can significantly reduce frictional heat generation while increasing the cutting force and enhancing the temperature rise. The parameter valuation of the newly defined parameter η, which is related to frictional heating, shows that the capacity of the thermal generation and the heat transfer change as the temperature rises at the cutter-rock interface. At last, the correlation analysis indicates that the cutting force of sandstone and granite is highly correlated with , E/σc and σt. This study serves as a theoretical support and technical guidance for cutting hot dry rock (HDR), which is of great significance to HDR drilling.展开更多
CO_(2) drilling is a promising underbalance drilling technology with great advantages,such as lower cutting force,intense cooling and excellent lubrication.However,in the underbalance drilling,the mechanism of the cou...CO_(2) drilling is a promising underbalance drilling technology with great advantages,such as lower cutting force,intense cooling and excellent lubrication.However,in the underbalance drilling,the mechanism of the coupling CO_(2) jet and polycrystalline-diamond-compact(PDC)cutter are still unclear.Whereby,we established a coupled smoothed particle hydrodynamics/finite element method(SPH/FEM)model to simulate the composite rock-breaking of high-pressure CO_(2) jet&PDC cutter.Combined with the experimental research results,the mechanism of composite rock-breaking is studied from the perspectives of rock stress field,cutting force and jet field.The results show that the composite rock-breaking can effectively relieve the influence of vibration and shock on PDC cutter.Meanwhile,the high-pressure CO_(2) jet has a positive effect on carrying rock debris,which can effectively reduce the temperature rising and the thermal wear of the PDC cutter.In addition,the effects of CO_(2) jet parameters on composite rock-breaking were studied,such as jet impact velocity,nozzle diameter,jet injection angle and impact distance.The studies show that when the impact velocity of the CO_(2) jet is greater than 250 m/s,the CO_(2) jet could quickly break the rock.It is found that the optimal range of nozzle diameter is 1.5–2.5 mm,the best injection angle of CO_(2) jet is 60,the optimal impact distance is 10 times the nozzle diameter.The above studies could provide theoretical supports and technical guidance for composite rock-breaking,which is useful for the CO_(2) underbalance drilling and drill bit design.展开更多
BACKGROUND Association between tea consumption and incident hypertension remains uncertain.This study conducted to examine the health effects of tea consumption on blood pressure progression and hypertension incidence...BACKGROUND Association between tea consumption and incident hypertension remains uncertain.This study conducted to examine the health effects of tea consumption on blood pressure progression and hypertension incidence.METHODS A population-based cohort of 38,913 Chinese participants without hypertension at baseline were included in the current study.Information on tea consumption was collected through standardized questionnaires.Associations of tea consump-tion with blood pressure progression and incident hypertension were analyzed using logistic regression models and Cox propor-tional hazards regression models,respectively.RESULTS During a median follow-up of 5.9 years,17,657 individuals had experienced progression to a higher blood pressure stage and 5,935 individuals had developed hypertension.In multivariate analyses,habitual tea drinkers(≥3 times/week for at least six months)had a 17%lower risk for blood pressure progression[odds ratio(OR)=0.83,95%CI:0.79-0.88]and a 14%de-creased risk for incident hypertension[hazard ratio(HR)=0.86,95%CI:0.80-0.91]compared with non-habitual tea drinkers.In-dividuals in different baseline blood pressure groups could obtain similar benefit from habitual tea drinking.In terms of tea con-sumption amount,an inverse,linear dose-response relation between monthly consumption of tea leaves and risk of blood pres-sure progression was observed,while the risk of incident hypertension did not reduce further after consuming around 100 g of tea leaves per month.CONCLUSIONS Our study demonstrated that habitual tea consumption could provide preventive effect against blood pres-sure progression and hypertension incidence.展开更多
The exploitation of shale gas is promising due to depletion of the conventional energy and intensification of the greenhouse effect.In this paper,we proposed a heat-fluid-solid coupling damage model of supercritical C...The exploitation of shale gas is promising due to depletion of the conventional energy and intensification of the greenhouse effect.In this paper,we proposed a heat-fluid-solid coupling damage model of supercritical CO_(2)(SC-CO_(2))compound fracturing which is expected to be an efficient and environmentally friendly way to develop shale gas.The coupling model is solved by the finite element method,and the results are in good agreement with the analytical solutions and fracturing experiments.Based on this model,the fracture propagation characteristics at the two stages of compound fracturing are studied and the influence of pressurization rate,in situ stress,bedding angle,and other factors are considered.The results show that at the SC-CO_(2)fracturing stage,a lower pressurization rate is conducive to formation of the branches around main fractures,while a higher pressurization rate inhibits formation of the branches around main fractures and promotes formation of the main fractures.Both bedding and in situ stress play a dominant role in the fracture propagation.When the in situ stress ratio(δ_(x)/δ_(y))is 1,the presence of bedding can reduce the initiation pressure and failure pressure.Nevertheless,it will cause the fracture to propagate along the bedding direction,reducing the fracture complexity.In rocks without bedding,hydraulic fracturing has the lengthening and widening effects for SC-CO_(2)induced fracture.In shale,fractures induced at the hydraulic fracturing stage are more likely to be dominated by in situ stresses and have a shorter reorientation radius.Therefore,fracture branches propagating along the maximum principal stress direction may be generated around the main fractures induced by SC-CO_(2)at the hydraulic fracturing stage.When the branches converge with the main fractures,fracture zones are easily formed,and thus the fracture complexity and damage area can be significantly increased.The results are instructive for the design and application of SC-CO_(2)compound fracturing.展开更多
OBJECTIVES Moderate to vigorous physical activity is recommended to prevent hypertension according to the current guidelines.However,the degree to which the total physical activity(TPA)and its changes benefit normoten...OBJECTIVES Moderate to vigorous physical activity is recommended to prevent hypertension according to the current guidelines.However,the degree to which the total physical activity(TPA)and its changes benefit normotensives and hypertensives is uncertain.We aimed to examine the effects of TPA and its changes on the incidence,progression,and remission of hypertension in the large-scale prospective cohorts.METHODS A total of 73,077 participants(55,101 normotensives and 17,976 hypertensives)were eligible for TPA analyses.During a mean follow-up of 7.16 years(394,038 person-years),12,211 hypertension cases were identified.TPA was estimated as metabolic equivalents and categorized into quartiles.Cox proportional hazards regression and multivariable logistic regression were used to estimate associations of TPA and changes in TPA with incident hypertension and progression/remission of hypertension.RESULTS Compared with the lowest quartile of TPA,normotensives at the third and the highest quartile had a decreased risk of incident hypertension,with hazard ratios(HRs)of 0.86[95%confidence interval(CI):0.81−0.91]and 0.81(95%CI:0.77−0.86),respectively.Hypertensives at the highest quartile of TPA demonstrated a decreased risk of progression of hypertension[odds ratio(OR)=0.87,95%CI:0.79−0.95],and an increased probability of hypertension remission(OR=1.17,95%CI:1.05−1.29).Moreover,getting active from a sedentary lifestyle during the follow-up period could reduce 25%(HR=0.75,95%CI:0.58−0.96)risk of incident hypertension,whereas those becoming sedentary did not achieve benefit from initially being active.CONCLUSIONS Our findings indicated that increasing and maintaining TPA levels could benefit normotensives,whereas higher TPA levels were needed to effectively control progression and improve remission of hypertension.Physical activity played undoubtedly an essential role in both primary and secondary prevention of hypertension.展开更多
To investigate fracture generation and strain variation during SC-CO_(2)(supercritical carbon dioxide)jet fracturing,the model of induced strain is established and the experiments are comprehensively studied.The influ...To investigate fracture generation and strain variation during SC-CO_(2)(supercritical carbon dioxide)jet fracturing,the model of induced strain is established and the experiments are comprehensively studied.The influence factors are comprehensively explored,such as jet pressure,ambient pressure,etc.With the increasing jet pressure,the fracture morphology changes from parallel cracks to oblique cracks.Both the mass loss of specimen and CO_(2) absorption increase significantly,and the growth rate and minimum value of strain also rise exponentially.Under a high ambient pressure of 8.0 MPa,the main fractures mostly propagated from the surface to the bottom surface of the specimen.The maximum strain and the stable duration under higher ambient pressure are 1.5 times and 10 times,respectively,of the case under the ambient pressure of 5.0 MPa.The comparison shows that the optimal jet distance is 5-7 times the nozzle diameter,resulting in massive mass loss,large CO_(2)absorption,and peak strain.Moreover,the nonlinear variation of strain curve during jet pressurization is related to the type of rock and ambient pressure.These studies clearly show the relationship between the fracture morphology and induced strain,which are crucial for SC-CO_(2)fracturing in shale gas reservoirs.展开更多
Objective Calcium Voltage-Gated Channel Subunit Alpha1 C(CACNA1C)gene encodes an alpha-1 subunit of a voltage-dependent calcium channel.This subunit forms the pore through which calcium ions pass into the cell and pla...Objective Calcium Voltage-Gated Channel Subunit Alpha1 C(CACNA1C)gene encodes an alpha-1 subunit of a voltage-dependent calcium channel.This subunit forms the pore through which calcium ions pass into the cell and plays an important role in regulating blood pressure.Smoking habit has been proven become the risk factor of hypertension.This study aimed to investigate the interaction of variants in CACNA1C gene with smoke in blood pressure(BP)responses to dietary sodium and potassium intervention.展开更多
The supercritical carbon dioxide(SC-CO2)jet has a wide application prospect for rock breaking and jet fracturing in the development of the unconventional shale energy,due to its special physicochemical properties.To i...The supercritical carbon dioxide(SC-CO2)jet has a wide application prospect for rock breaking and jet fracturing in the development of the unconventional shale energy,due to its special physicochemical properties.To investigate its jet flow characteristics,the high-speed photography is used in experiments and the simulations through a compressible numerical model are carried out.It is shown that the jet flow field can be divided into three typical regions,the mixing layer possesses the same characteristics as a gas/gas turbulent mixing layer,with the divergent angles evidently smaller than those of the incompressible jets.The predicted results by the numerical model are in a good agreement with those of the experimentations.Through the dimensionless analysis,the potential core shows a length of about 9d and an increasing trend with the increase of the inlet pressure while the decay rate shows a decreasing trend,and the radial profiles consistent well with the 41 Ue-η''normalized method.In addition,a significant temperature drop of the SC-CO2 is observed between the nozzle inlet and the exit.A simple and convenient semi-empirical equation for calculating this temperature variation is deduced.Finally,the flow characteristics suggest that the SC-CO2 jet should be treated as a compressible jet.展开更多
Although several theoretical calculation methods for high-pressure jet are available,there is currently no theoretical model for the high-pressure CO_(2)jet based on the high-precision equation of state(EOS).To invest...Although several theoretical calculation methods for high-pressure jet are available,there is currently no theoretical model for the high-pressure CO_(2)jet based on the high-precision equation of state(EOS).To investigate the flow field of the high-pressure CO_(2)jet in cases of the composite rock-breaking under the high-pressure CO_(2)Jet and PDC cutter,a semi-analytical approach of the high-pressure CO_(2)jet is developed based on the Span-Wagner EOS and CO_(2)jet theory.The semi-analytical calculations and the physical property calculations under the action of the high-pressure CO_(2)jet are conducted with consideration of the jet pressure,the jet distance,the nozzle diameter and the jet angle.The results indicate that the distribution of the physical properties calculated by the semi-analytical approaches is similar to that obtained by experimental monitoring and numerical simulation,which indicates that the calculation method of the high-pressure CO_(2)jet presented in this paper is effective and reliable.The properties of the CO_(2)jet obtained by the theoretical calculation see a significant difference between the initial region and the jet impact region.At the temperature of 300 K,the increase of the initial pressure can effectively increase the impact force and the cooling ability of the jet.The proportion of the jet core lengths in the jet on the axis increases with the increase of the ratio of the nozzle diameter to the jet length,accompanied with the increase of the impact force of the jet.The increase of the jet angle can effectively increase the impacting force of the jet,but hampers the fluid diffusion.The study combines the theoretical calculation of the jet with the calculation of the physical properties of the high-pressure CO_(2),for comprehensively understanding the CO_(2)jet field in the composite rock-breaking under the action of the high-pressure CO_(2)jet and PDC cutter.This theoretical calculation of the CO_(2)jet based on the high-precision EOS provides an option for the convenient calculation of the CO_(2)drilling in practical engineering.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52004236)the Key Program of National Natural Science Foundation of China(Grant No.52234003)+2 种基金Sichuan Provincial Returned Scholars'Scientific and Technological Activities Merit-based Funding Programs(Grant No.2023016)Open project of the International Joint Research Center for Deep Earth Drilling and Deep Earth Resources Development of the Ministry of Science and Technology(Grant No.DEDRD-2023-06)the National Natural Science Foundation of China Outstanding Youth Science Fund Program(Grant No.52222402).
文摘Geothermal energy is a clean and ecologically friendly energy source with significant potential. The temperature variations between the Polycrystalline Diamond Compact (PDC) cutter and the rock of the reservoir are the key factors affecting the cutting performance when drilling through formations with thermally damaged rock. To better investigate the temperature rise, a series of rock samples treated at high temperatures (9–300℃) were broken with a PDC cutter. The performance of the PDC cutter on these samples was studied using cutting force sensors, high-speed photography, and the thermal infrared imager. Based on the experimental data, a new cutting force evaluation parameter, η, is suggested. The link between the cutting force and rock properties is discussed in detail. The present results indicate that the average cutting force of high-temperature-treated granite is 3–5 times that of the thermally damaged sandstone. Furthermore, a critical temperature for thermal damage has been identified in granite cutting at 100–200℃ and in sandstone at 100℃. This corresponds to the temperature at which interlayer water loss and thermal crack closure occur. The results also indicate that when the treatment temperature exceeds the critical threshold, both the cutting force and temperature rise exhibit more significant changes with increasing temperature. Additionally, the maximum temperature of the PDC cutter during granite cutting can reach 47.6 ℃, which is almost 34℃ higher than that of sandstone. Regarding debris size, granite is much less sensitive to the treatment temperature, showing only slight changes in debris size compared to sandstone as the treatment temperature increases. The increasing cutter-rock interface area can significantly reduce frictional heat generation while increasing the cutting force and enhancing the temperature rise. The parameter valuation of the newly defined parameter η, which is related to frictional heating, shows that the capacity of the thermal generation and the heat transfer change as the temperature rises at the cutter-rock interface. At last, the correlation analysis indicates that the cutting force of sandstone and granite is highly correlated with , E/σc and σt. This study serves as a theoretical support and technical guidance for cutting hot dry rock (HDR), which is of great significance to HDR drilling.
基金This work was supported by the National Natural Science Foundation of China(No.52004236)Sichuan Science and Technology Program(No.2021JDRC0114)+4 种基金the Starting Project of Southwest Petroleum University(No.2019QHZ009)the China Postdoctoral Science Foundation(No.2020M673285)the Open Project Program of Key Laboratory of Groundwater Resources and Environment(Jilin University)Ministry of Education(No.202005009KF)the Chinese Scholarship Council(CSC)funding(No.202008515107).
文摘CO_(2) drilling is a promising underbalance drilling technology with great advantages,such as lower cutting force,intense cooling and excellent lubrication.However,in the underbalance drilling,the mechanism of the coupling CO_(2) jet and polycrystalline-diamond-compact(PDC)cutter are still unclear.Whereby,we established a coupled smoothed particle hydrodynamics/finite element method(SPH/FEM)model to simulate the composite rock-breaking of high-pressure CO_(2) jet&PDC cutter.Combined with the experimental research results,the mechanism of composite rock-breaking is studied from the perspectives of rock stress field,cutting force and jet field.The results show that the composite rock-breaking can effectively relieve the influence of vibration and shock on PDC cutter.Meanwhile,the high-pressure CO_(2) jet has a positive effect on carrying rock debris,which can effectively reduce the temperature rising and the thermal wear of the PDC cutter.In addition,the effects of CO_(2) jet parameters on composite rock-breaking were studied,such as jet impact velocity,nozzle diameter,jet injection angle and impact distance.The studies show that when the impact velocity of the CO_(2) jet is greater than 250 m/s,the CO_(2) jet could quickly break the rock.It is found that the optimal range of nozzle diameter is 1.5–2.5 mm,the best injection angle of CO_(2) jet is 60,the optimal impact distance is 10 times the nozzle diameter.The above studies could provide theoretical supports and technical guidance for composite rock-breaking,which is useful for the CO_(2) underbalance drilling and drill bit design.
基金the National Nature Science Foundation of China(No.91643208)the Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences(2017-I2M-1-004&2019-I2M-2-003)the National Key Research&Development Program of China(2017YFC0211700&2018YFE0115300)。
文摘BACKGROUND Association between tea consumption and incident hypertension remains uncertain.This study conducted to examine the health effects of tea consumption on blood pressure progression and hypertension incidence.METHODS A population-based cohort of 38,913 Chinese participants without hypertension at baseline were included in the current study.Information on tea consumption was collected through standardized questionnaires.Associations of tea consump-tion with blood pressure progression and incident hypertension were analyzed using logistic regression models and Cox propor-tional hazards regression models,respectively.RESULTS During a median follow-up of 5.9 years,17,657 individuals had experienced progression to a higher blood pressure stage and 5,935 individuals had developed hypertension.In multivariate analyses,habitual tea drinkers(≥3 times/week for at least six months)had a 17%lower risk for blood pressure progression[odds ratio(OR)=0.83,95%CI:0.79-0.88]and a 14%de-creased risk for incident hypertension[hazard ratio(HR)=0.86,95%CI:0.80-0.91]compared with non-habitual tea drinkers.In-dividuals in different baseline blood pressure groups could obtain similar benefit from habitual tea drinking.In terms of tea con-sumption amount,an inverse,linear dose-response relation between monthly consumption of tea leaves and risk of blood pres-sure progression was observed,while the risk of incident hypertension did not reduce further after consuming around 100 g of tea leaves per month.CONCLUSIONS Our study demonstrated that habitual tea consumption could provide preventive effect against blood pres-sure progression and hypertension incidence.
基金the funding support from the National Natural Science Foundation of China(Nos.52274093 and 52004236).
文摘The exploitation of shale gas is promising due to depletion of the conventional energy and intensification of the greenhouse effect.In this paper,we proposed a heat-fluid-solid coupling damage model of supercritical CO_(2)(SC-CO_(2))compound fracturing which is expected to be an efficient and environmentally friendly way to develop shale gas.The coupling model is solved by the finite element method,and the results are in good agreement with the analytical solutions and fracturing experiments.Based on this model,the fracture propagation characteristics at the two stages of compound fracturing are studied and the influence of pressurization rate,in situ stress,bedding angle,and other factors are considered.The results show that at the SC-CO_(2)fracturing stage,a lower pressurization rate is conducive to formation of the branches around main fractures,while a higher pressurization rate inhibits formation of the branches around main fractures and promotes formation of the main fractures.Both bedding and in situ stress play a dominant role in the fracture propagation.When the in situ stress ratio(δ_(x)/δ_(y))is 1,the presence of bedding can reduce the initiation pressure and failure pressure.Nevertheless,it will cause the fracture to propagate along the bedding direction,reducing the fracture complexity.In rocks without bedding,hydraulic fracturing has the lengthening and widening effects for SC-CO_(2)induced fracture.In shale,fractures induced at the hydraulic fracturing stage are more likely to be dominated by in situ stresses and have a shorter reorientation radius.Therefore,fracture branches propagating along the maximum principal stress direction may be generated around the main fractures induced by SC-CO_(2)at the hydraulic fracturing stage.When the branches converge with the main fractures,fracture zones are easily formed,and thus the fracture complexity and damage area can be significantly increased.The results are instructive for the design and application of SC-CO_(2)compound fracturing.
文摘OBJECTIVES Moderate to vigorous physical activity is recommended to prevent hypertension according to the current guidelines.However,the degree to which the total physical activity(TPA)and its changes benefit normotensives and hypertensives is uncertain.We aimed to examine the effects of TPA and its changes on the incidence,progression,and remission of hypertension in the large-scale prospective cohorts.METHODS A total of 73,077 participants(55,101 normotensives and 17,976 hypertensives)were eligible for TPA analyses.During a mean follow-up of 7.16 years(394,038 person-years),12,211 hypertension cases were identified.TPA was estimated as metabolic equivalents and categorized into quartiles.Cox proportional hazards regression and multivariable logistic regression were used to estimate associations of TPA and changes in TPA with incident hypertension and progression/remission of hypertension.RESULTS Compared with the lowest quartile of TPA,normotensives at the third and the highest quartile had a decreased risk of incident hypertension,with hazard ratios(HRs)of 0.86[95%confidence interval(CI):0.81−0.91]and 0.81(95%CI:0.77−0.86),respectively.Hypertensives at the highest quartile of TPA demonstrated a decreased risk of progression of hypertension[odds ratio(OR)=0.87,95%CI:0.79−0.95],and an increased probability of hypertension remission(OR=1.17,95%CI:1.05−1.29).Moreover,getting active from a sedentary lifestyle during the follow-up period could reduce 25%(HR=0.75,95%CI:0.58−0.96)risk of incident hypertension,whereas those becoming sedentary did not achieve benefit from initially being active.CONCLUSIONS Our findings indicated that increasing and maintaining TPA levels could benefit normotensives,whereas higher TPA levels were needed to effectively control progression and improve remission of hypertension.Physical activity played undoubtedly an essential role in both primary and secondary prevention of hypertension.
基金the National Natural Science Foundation of China(Grant No.52004236)Sichuan Science and Technology Program(Grant No.2021JDRC0114)+3 种基金the Starting Project of SWPU(Grant No.2019QHZ009)the China Postdoctoral Science Foundation(Grant No.2020M673285)the Open Project Program of Key Laboratory of Groundwater Resources and Environment(Jilin University),Ministry of Education(Grant No.202005009KF)the National Key Basic Research Program of China(Grant No.2014CB239203)for the financial support of this work。
文摘To investigate fracture generation and strain variation during SC-CO_(2)(supercritical carbon dioxide)jet fracturing,the model of induced strain is established and the experiments are comprehensively studied.The influence factors are comprehensively explored,such as jet pressure,ambient pressure,etc.With the increasing jet pressure,the fracture morphology changes from parallel cracks to oblique cracks.Both the mass loss of specimen and CO_(2) absorption increase significantly,and the growth rate and minimum value of strain also rise exponentially.Under a high ambient pressure of 8.0 MPa,the main fractures mostly propagated from the surface to the bottom surface of the specimen.The maximum strain and the stable duration under higher ambient pressure are 1.5 times and 10 times,respectively,of the case under the ambient pressure of 5.0 MPa.The comparison shows that the optimal jet distance is 5-7 times the nozzle diameter,resulting in massive mass loss,large CO_(2)absorption,and peak strain.Moreover,the nonlinear variation of strain curve during jet pressurization is related to the type of rock and ambient pressure.These studies clearly show the relationship between the fracture morphology and induced strain,which are crucial for SC-CO_(2)fracturing in shale gas reservoirs.
文摘Objective Calcium Voltage-Gated Channel Subunit Alpha1 C(CACNA1C)gene encodes an alpha-1 subunit of a voltage-dependent calcium channel.This subunit forms the pore through which calcium ions pass into the cell and plays an important role in regulating blood pressure.Smoking habit has been proven become the risk factor of hypertension.This study aimed to investigate the interaction of variants in CACNA1C gene with smoke in blood pressure(BP)responses to dietary sodium and potassium intervention.
基金the National Key Basic Research Development Program of China(973 Program,Grant No.2014CB239203)the National Natural Science Foundation of China(Grant No.51474158)the Program for New Century Excellent Talents in University of Ministry of Education(Grant No.NCET-12-0424).
文摘The supercritical carbon dioxide(SC-CO2)jet has a wide application prospect for rock breaking and jet fracturing in the development of the unconventional shale energy,due to its special physicochemical properties.To investigate its jet flow characteristics,the high-speed photography is used in experiments and the simulations through a compressible numerical model are carried out.It is shown that the jet flow field can be divided into three typical regions,the mixing layer possesses the same characteristics as a gas/gas turbulent mixing layer,with the divergent angles evidently smaller than those of the incompressible jets.The predicted results by the numerical model are in a good agreement with those of the experimentations.Through the dimensionless analysis,the potential core shows a length of about 9d and an increasing trend with the increase of the inlet pressure while the decay rate shows a decreasing trend,and the radial profiles consistent well with the 41 Ue-η''normalized method.In addition,a significant temperature drop of the SC-CO2 is observed between the nozzle inlet and the exit.A simple and convenient semi-empirical equation for calculating this temperature variation is deduced.Finally,the flow characteristics suggest that the SC-CO2 jet should be treated as a compressible jet.
基金This work was supported by the Sichuan Science and Technology Program(Grant No.2021JDRC0114)the Starting Project of Southwest Petroleum University(Grant No.2019QHZ009)+2 种基金the China Postdoctoral Science Foundation(Grant No.2020M673285)the Open Project Program of Key Laboratory of Groundwater Resources and Environment,Ministry of Education,Jilin University(Grant No.202005009KF)the Chinese Scholarship Council funding(Grant No.202008515107).
文摘Although several theoretical calculation methods for high-pressure jet are available,there is currently no theoretical model for the high-pressure CO_(2)jet based on the high-precision equation of state(EOS).To investigate the flow field of the high-pressure CO_(2)jet in cases of the composite rock-breaking under the high-pressure CO_(2)Jet and PDC cutter,a semi-analytical approach of the high-pressure CO_(2)jet is developed based on the Span-Wagner EOS and CO_(2)jet theory.The semi-analytical calculations and the physical property calculations under the action of the high-pressure CO_(2)jet are conducted with consideration of the jet pressure,the jet distance,the nozzle diameter and the jet angle.The results indicate that the distribution of the physical properties calculated by the semi-analytical approaches is similar to that obtained by experimental monitoring and numerical simulation,which indicates that the calculation method of the high-pressure CO_(2)jet presented in this paper is effective and reliable.The properties of the CO_(2)jet obtained by the theoretical calculation see a significant difference between the initial region and the jet impact region.At the temperature of 300 K,the increase of the initial pressure can effectively increase the impact force and the cooling ability of the jet.The proportion of the jet core lengths in the jet on the axis increases with the increase of the ratio of the nozzle diameter to the jet length,accompanied with the increase of the impact force of the jet.The increase of the jet angle can effectively increase the impacting force of the jet,but hampers the fluid diffusion.The study combines the theoretical calculation of the jet with the calculation of the physical properties of the high-pressure CO_(2),for comprehensively understanding the CO_(2)jet field in the composite rock-breaking under the action of the high-pressure CO_(2)jet and PDC cutter.This theoretical calculation of the CO_(2)jet based on the high-precision EOS provides an option for the convenient calculation of the CO_(2)drilling in practical engineering.
