According to the requirements of College English Teaching Guide,together with the freshmen’s majors and the actual English level in SASU(Sichuan University of Arts and Science),College English stratified teaching has...According to the requirements of College English Teaching Guide,together with the freshmen’s majors and the actual English level in SASU(Sichuan University of Arts and Science),College English stratified teaching has been implemented in SASU since 2016.In order to completely master the teaching effect of the stratified teaching in the past four years,a questionnaire survey on College English learners has been carried out.On the basis of the feedback report and the teaching principles of College English under the network environment,this paper puts forward the optimization strategies and rectification suggestions.展开更多
BACKGROUND Smartwatches have become readily accessible tools for detecting atrial fibrillation(AF).There remains limited data on how they affect psychosocial outcomes and engagement in older adults.We examine the heal...BACKGROUND Smartwatches have become readily accessible tools for detecting atrial fibrillation(AF).There remains limited data on how they affect psychosocial outcomes and engagement in older adults.We examine the health behavior outcomes of stroke survivors prescribed smartwatches for AF detection stratified by age.METHODS We analyzed data from the Pulsewatch study,a randomized controlled trial that enrolled patients(≥50 years)with a history of stroke or transient ischemic attack and CHA2DS2-VASc≥2.Intervention participants were equipped with a cardiac patch monitor and a smartwatch-app dyad,while control participants wore the cardiac patch monitor for up to 44 days.We evaluated health behavior parameters using standardized tools,including the Consumer Health Activation Index,the Generalized Anxiety Disorder questionnaire,the 12-Item Short Form Health Survey,and wear time of participants categorized into three age groups:Group 1(ages 50-60),Group 2(ages 61-69),and Group 3(ages 70-87).We performed statistical analysis using a mixedeffects repeated measures linear regression model to examine differences amongst age groups.RESULTS Comparative analysis between Groups 1,2 and 3 revealed no significant differences in anxiety,patient activation,perception of physical health and wear time.The use of smartwatch technology was associated with a decrease in perception of mental health for Group 2 compared to Group 1(β=-3.29,P=0.046).CONCLUSION Stroke survivors demonstrated a willingness to use smartwatches for AF monitoring.Importantly,among these study participants,the majority did not experience negative health behavior outcomes or decreased engagement as age increased.展开更多
Objective:To explore the application effect of stratified nursing intervention based on the background of misinspiration risk assessment in mechanically ventilated patients in intensive care unit(ICU).Methods:100 case...Objective:To explore the application effect of stratified nursing intervention based on the background of misinspiration risk assessment in mechanically ventilated patients in intensive care unit(ICU).Methods:100 cases of mechanically ventilated patients who were admitted to the ICU of our hospital from March 2022 to March 2023 were selected and divided into an observation group and a control group according to the random number table method,with 50 cases in each of the two groups.The control group was given routine care in ICU,and the observation group was given stratified nursing interventions based on the background of the risk of aspiration assessment on the basis of the control group,and both groups were cared for until they were transferred out of the ICU,and the mechanical ventilation time,ICU stay time,muscle strength score,complication rate,adherence,and satisfaction were observed and compared between the two groups.Results:The mechanical ventilation time and ICU stay time of the observation group were shorter than that of the control group after the intervention;the muscle strength score,compliance and satisfaction of the observation group were higher than that of the control group after the intervention;and the complication rate of the observation group was lower than that of the control group after the intervention,all of which were P<0.05.Conclusion:The application of stratified nursing intervention based on the background of misaspiration risk assessment in ICU mechanically ventilated patients can improve the patient's muscle strength,shorten the time of mechanical ventilation,promote the patient's recovery,reduce the occurrence of complications,and improve the patient's compliance and satisfaction.展开更多
The practice of stratified English teaching is determined by the features of vocational education. In addition, it is an inexorable trend of current higher education reform, and also a fundamental demand of higher voc...The practice of stratified English teaching is determined by the features of vocational education. In addition, it is an inexorable trend of current higher education reform, and also a fundamental demand of higher vocational education and quality-oriented education. This thesis argues for the need of stratified English teaching in high vocational colleges.展开更多
A high-density, high-flux circulating fluidized bed (CFB) riser (100 mm in ID and 10.614 m in height) was applied in a wide range of operating conditions (with solid fluxes up to 400 kg/m2s and superficial gas velocit...A high-density, high-flux circulating fluidized bed (CFB) riser (100 mm in ID and 10.614 m in height) was applied in a wide range of operating conditions (with solid fluxes up to 400 kg/m2s and superficial gas velocities up to 12 m/s) to examine its radial non-uniformity dynamics. The solids holdup was determined through the use of a fiber-optic probe at 11 axial levels. The results indicated that under all operating conditions, the high superficial gas velocity and low solid fluxes maintained a low radial non-uniformity index (RNI). The high-density/flux CFB riser had several unique characteristics, so that the peak of the radial solids holdup profile occurred at a position with r/R=0.8. The RNI and solids holdup at the cross-sectional position had a good logarithmic relationship at the low-density condition (with a mean solids holdup of <0.2), and the RNI decreased when the mean solids holdup exceeded 0.2. Investigation of the dynamics of stratified injection revealed that the feed ratio had an important effect on Gs and on solids holdup distribution. A novel "<" shaped axial solids holdup profile was found. Gs decreased sharply when the up-flow feed ratio exceeded 0.5, and RNI was lowest when the up-flow feed ratio was 1.展开更多
The evaluation of education in the training process is important for students, and its importance is at the level of students and thecorresponding level of evaluation. Understanding the guidance and training of the mi...The evaluation of education in the training process is important for students, and its importance is at the level of students and thecorresponding level of evaluation. Understanding the guidance and training of the middle school football team is an important partof rapidly improving the level of Chinese football. It is necessary to adapt to the development characteristics of middle schoolstudents and conduct reasonable guidance training. Plans must be strengthened to implement training programs. On the trainingschedule, we must balance learning and training, and must fully consider the growth of students. As part of a layered education,stratified evaluation has the unique advantages of basic education and secondary education. The evaluation of the students whofocus on various levels of learning. Football coaching and training requires a full display of the student's personality. The teacher'sstratified evaluation method is very important for improving students' confidence in learning, enhancing students' enthusiasm forfootball training, and promoting students' continuous improvement. This study takes the application of stratified evaluation in theteaching and training of middle school football as the research direction, and puts forward reasonable suggestions by analyzing thetraining cases of the layered evaluation.展开更多
In this paper,for the first time,we investigated the combined effect of subsurface dams and a typical stratified aquifer(two high-permeability layers with a low-permeability layer between them)on groundwater flow and ...In this paper,for the first time,we investigated the combined effect of subsurface dams and a typical stratified aquifer(two high-permeability layers with a low-permeability layer between them)on groundwater flow and salinity distribution in a tidally influenced coastal unconfined aquifer.Subsurface dams can inhibit the invasion of saltwater,and the low-permeability layer(LPL)and tide action can increase the effect of subsurface dams and the removal rate of residual saltwater.Through sensitivity analysis,it was discovered that shifting the dam location towards the inland resulted in a reduction in the effective heights of the dam.The upper saline plume contracted with increasing dam height,and the upper boundary of LPL was moved to shallower regions.And the natural removal time increased significantly with increasing dam height and the bottom boundary of LPL was moved to deeper regions.In addition,if the dam location was close to the sea boundary and the bottom boundary of LPL was moved to deeper regions,we could increase the subsurface dam height to reduce the risks of control of saltwater intrusion.This study provides us a comprehensive understanding of the complex hydrodynamics of saltwater intrusion and provides guides for the design of subsurface dams aimed at saltwater intrusion control in stratified coastal aquifers.展开更多
Wax deposition in oil-water stratified flow is commonly encountered onshore and offshore oil production pipe systems,and typically reduces transportation capacity of oil.The accurate predicted model of wax deposition ...Wax deposition in oil-water stratified flow is commonly encountered onshore and offshore oil production pipe systems,and typically reduces transportation capacity of oil.The accurate predicted model of wax deposition has becomes an indispensable approach to design effective remediation strategies.However,a reliable mechanistic model for wax deposition prediction in oil-water two-phase stratified pipe flow is lacking to validate the deposition process.In this work,a three-dimensional(axial,radial,and angular)robust wax deposit model for oil-water stratified circular pipe flow was developed.The model of formation of a gel deposit based on the first principles of rheology was developed,associated with the results obtained from hydrodynamics and heat/mass transfer simulations.The predictions for wax deposition are found to compare satisfactorily with experimental data with two different oils for single phase and four different water cuts for oil-water stratified pipe flow.It can be seen from the wax gelation mechanism that an increase in water cut can help to reduce the wall/oil-deposit interface shear stress,thereby leading to an increase in the degree of gelation as well as the deposit rate.Furthermore,a local deposit analysis in the circumferential direction was conducted,for water cut 75%and total flow rate 5 m3/h,which provided insights to understand that the thickness on pipe wall was roughly uniformly distributed locates near the top of the pipe and the nearer the position gets close to two points,where the oil-water interface contacts the inner wall,the deposition thickness quickly dropped to 0.It was attributed to the fact that a roughly uniformly thickness far away from the oil-water interface contact the inner wall resulted in the slowly changes temperature along the circumferential pipe wall wetted by oil.展开更多
Dynamic performance on solids flow with water in deviated tubing is essential for the reliability of pump and normal operation of horizontal and directional wells.Compared with coal-water flow in vertical tubing and s...Dynamic performance on solids flow with water in deviated tubing is essential for the reliability of pump and normal operation of horizontal and directional wells.Compared with coal-water flow in vertical tubing and sand-oil flow with high production in deviated tubing,solids deposition with water shows obvious non-symmetric distributions in deviated tubing from simulations and experiments.The mathematical model of two phase flow was developed under coupling conditions of deviated tubing,low flow rate and viscosity based on the kinetic theory of granular flow and first-order discrete scheme.The results show that solid-water stratified flow in deviated tubing can be divided into two zones of suspension bed and the moving bed throughout the flow field.The solid flowing velocity with water is negative and particles slide down at the bottom of moving bed zone.The process of solids flow with water in deviated tubing will produce pressure loss and consume the kinetic energy.The thickness of deposited layer and the flowing velocity of solids flow downward with water at the moving bed zone enhance with the decreased inlet flow rate and the increased particle size,tubing inside diameter(ID)and inclination angle.Solids are easier into suspension from the upper part of moving bed zone to suspension bed zone and more solid particles flow with water towards the tubing outlet with the increase of inlet flowing velocity.The decision is made to reduce the screen width,tubing ID and inclination angle to maintain to be greater than critical deposition velocity in order to prevent solids settling.And it provides the theoretical basis and technical reserves for solid control and offers an effective approach to enhance tubing cleaning in deviated strings.展开更多
A stratified wake has multiple flow regimes,and exhibits different behaviors in these regimes due to the competing physical effects of momentum and buoyancy.This work aims at automated classification of the weakly and...A stratified wake has multiple flow regimes,and exhibits different behaviors in these regimes due to the competing physical effects of momentum and buoyancy.This work aims at automated classification of the weakly and the strongly stratified turbulence regimes based on information available in a full Reynolds stress model.First,we generate a direct numerical simulation database with Reynolds numbers from 10,000 to 50,000 and Froude numbers from 2 to 50.Order(100)independent realizations of temporally evolving wakes are computed to get converged statistics.Second,we train a linear logistic regression classifier with weight thresholding for automated flow regime classification.The classifier is designed to identify the physics critical to classification.Trained against data at one flow condition,the classifier is found to generalize well to other Reynolds and Froude numbers.The results show that the physics governing wake evolution is universal,and that the classifier captures that physics.展开更多
This research focused on the study of heat and mass transfers in a two-phase stratified turbulent fluid flow in a geothermal pipe with chemical reaction. The derived non-linear partial differential equations governing...This research focused on the study of heat and mass transfers in a two-phase stratified turbulent fluid flow in a geothermal pipe with chemical reaction. The derived non-linear partial differential equations governing the flow were solved using the Finite Difference Method. The effects of various physical parameters on the concentration, skin friction, heat, and mass transfers have been determined. Analysis of the results obtained indicated that the coefficient of skin friction decreased with an increase in Reynolds number and solutal Grasholf number, the rate of heat transfer increased with an increase in Eckert number, Prandtl number, and angle of inclination, and the rate of mass transfer increased with increase in Reynolds number, Chemical reaction parameter and angle of inclination. The findings would be useful to engineers in designing and maintaining geothermal pipelines more effectively.展开更多
BACKGROUND Transjugular intrahepatic portosystemic shunt(TIPS)has been extensively used to treat portal hypertension-associated complications,including cirrhosis.The prediction of post-TIPS prognosis is important for ...BACKGROUND Transjugular intrahepatic portosystemic shunt(TIPS)has been extensively used to treat portal hypertension-associated complications,including cirrhosis.The prediction of post-TIPS prognosis is important for cirrhotic patients,as more aggressive liver transplantation is needed when the post-TIPS prognosis is poor.AIM To construct a nutrition-based model that could predict the disease progression of cirrhotic patients after TIPS implantation in a sex-dependent manner.METHODS This study retrospectively recruited cirrhotic patients undergoing TIPS implantation for analysis.Muscle quality was assessed by measuring the skeletal muscle index(SMI)by computed tomography.Multivariate Cox proportional hazard models were utilized to determine the association between SMI and disease progression in cirrhotic patients after TIPS implantation.RESULTS This study eventually included 186 cirrhotic patients receiving TIPS who were followed up for 30.5±18.8 mo.For male patients,the 30-mo survival rate was significantly lower and the probability of progressive events was higher(3.257-fold)in the low-level SMI group than in the high-level SMI group.According to the multivariate Cox analysis of male patients,SMI<32.8 was an independent risk factor for long-term adverse outcomes after TIPS implantation.A model was constructed,which involved creatinine,plasma ammonia,SMI,and acute-on-chronic liver failure and hepatic encephalopathy occurring within half a year after surgery.This model had an area under the receiver operating characteristic curve of 0.852,sensitivity of 0.926,and specificity of 0.652.According to the results of the DeLong test,this model outperformed other models(Child-Turcotte-Pugh,Model for End-Stage Liver Disease,and Freiburg index of post-TIPS survival)(P<0.05).CONCLUSION SMI is strongly associated with poor long-term outcomes in male patients with cirrhosis who underwent TIPS implantation.展开更多
In this study,the damping responses of uniform soil,equi-proportional fly ash,and local soil as a single unit were investigated.The large-strain cyclic triaxial tests were performed for the specimen compacted at the d...In this study,the damping responses of uniform soil,equi-proportional fly ash,and local soil as a single unit were investigated.The large-strain cyclic triaxial tests were performed for the specimen compacted at the desired density(95%e99%of maximum dry density).The compacted specimens were tested under the loading frequency of 0.3e1 Hz with medium confinement of 70e100 kPa.Also,the unsymmetrical behavior of the hysteresis loop was analyzed using three different damping estimation approaches,i.e.symmetric hysteresis loop(SHL),asymmetric hysteresis loop(ASHL),and the modified American Society for Testing and Materials(ASTM)method.The outcome of the study shows for fly ash,local soil,and layered soil-ash,the ASHL technique has the highest damping value,followed by ASTM and then the SHL approach.The specimens prepared under high density and subjected to high confinement show low damping values.However,the specimens tested at high frequency exhibits high damping behavior.Similarly,the damping value of fly ash determined using the SHL and ASHL methods has a similar profile and reaches a maximum at 1%shear strain value before decreasing.The composite stratified deposit exhibits more dependency on relative compaction,confining pressure,and less on loading frequency.Based on the results,it is highly recommended to use the ASHL approach,especially under large strain conditions irrespective of soil type.The maximum damping ratio of stratified deposits is always in between the damping ratio of local soil and fly ash.The damping ratio of stratified soil and local soil is slightly larger than that of the other soils,although the damping ratio of fly ash is equivalent to that of the sand and clayey soil.These results may be helpful in the accurate determination of the damping properties of the layered soil-ash system that is required in the seismic response analysis.展开更多
With the advancement of the new curriculum reform,many schools have put forward the idea of combing English reading with stratified teaching.Enhancing the effectiveness of reading English picture books is an important...With the advancement of the new curriculum reform,many schools have put forward the idea of combing English reading with stratified teaching.Enhancing the effectiveness of reading English picture books is an important goal that most English teachers uphold when reforming the teaching of English reading.In order to achieve this goal,it is necessary to improve the teaching methods of reading.Reading picture books is an important way to improve students5 core competencies in English.However,at present,the method of teaching reading in primary school is simple;in addition,the teaching activities are not well organized.Therefore,in order to improve students5 core competencies in English,this article points out several issues in the teaching of English picture book reading and provides some pedagogical implications for the teaching in this aspect based on the stratified teaching method and classroom observation by including Class 1,Grade 2 students from a primary school in Leshan as the research subjects.展开更多
基金This work was supported by Sichuan University of Arts and Science(2020JY023).
文摘According to the requirements of College English Teaching Guide,together with the freshmen’s majors and the actual English level in SASU(Sichuan University of Arts and Science),College English stratified teaching has been implemented in SASU since 2016.In order to completely master the teaching effect of the stratified teaching in the past four years,a questionnaire survey on College English learners has been carried out.On the basis of the feedback report and the teaching principles of College English under the network environment,this paper puts forward the optimization strategies and rectification suggestions.
基金funded by R01HL137734 from the National Heart,Lung,and Blood Institutesupported by F30HL149335 from the National Heart,Lung,and Blood Institute+3 种基金supported by NIH grant 2T32HL 120823supported by K23HL161432 from the National Heart,Lung,and Blood Institutesupported by R01 HL137734supported by R01HL126911,R01HL137734,R01HL137794,R01HL135219,R01HL136660,U54HL143541,and 1U01HL146382 from the National Heart,Lung,and Blood Institute.
文摘BACKGROUND Smartwatches have become readily accessible tools for detecting atrial fibrillation(AF).There remains limited data on how they affect psychosocial outcomes and engagement in older adults.We examine the health behavior outcomes of stroke survivors prescribed smartwatches for AF detection stratified by age.METHODS We analyzed data from the Pulsewatch study,a randomized controlled trial that enrolled patients(≥50 years)with a history of stroke or transient ischemic attack and CHA2DS2-VASc≥2.Intervention participants were equipped with a cardiac patch monitor and a smartwatch-app dyad,while control participants wore the cardiac patch monitor for up to 44 days.We evaluated health behavior parameters using standardized tools,including the Consumer Health Activation Index,the Generalized Anxiety Disorder questionnaire,the 12-Item Short Form Health Survey,and wear time of participants categorized into three age groups:Group 1(ages 50-60),Group 2(ages 61-69),and Group 3(ages 70-87).We performed statistical analysis using a mixedeffects repeated measures linear regression model to examine differences amongst age groups.RESULTS Comparative analysis between Groups 1,2 and 3 revealed no significant differences in anxiety,patient activation,perception of physical health and wear time.The use of smartwatch technology was associated with a decrease in perception of mental health for Group 2 compared to Group 1(β=-3.29,P=0.046).CONCLUSION Stroke survivors demonstrated a willingness to use smartwatches for AF monitoring.Importantly,among these study participants,the majority did not experience negative health behavior outcomes or decreased engagement as age increased.
文摘Objective:To explore the application effect of stratified nursing intervention based on the background of misinspiration risk assessment in mechanically ventilated patients in intensive care unit(ICU).Methods:100 cases of mechanically ventilated patients who were admitted to the ICU of our hospital from March 2022 to March 2023 were selected and divided into an observation group and a control group according to the random number table method,with 50 cases in each of the two groups.The control group was given routine care in ICU,and the observation group was given stratified nursing interventions based on the background of the risk of aspiration assessment on the basis of the control group,and both groups were cared for until they were transferred out of the ICU,and the mechanical ventilation time,ICU stay time,muscle strength score,complication rate,adherence,and satisfaction were observed and compared between the two groups.Results:The mechanical ventilation time and ICU stay time of the observation group were shorter than that of the control group after the intervention;the muscle strength score,compliance and satisfaction of the observation group were higher than that of the control group after the intervention;and the complication rate of the observation group was lower than that of the control group after the intervention,all of which were P<0.05.Conclusion:The application of stratified nursing intervention based on the background of misaspiration risk assessment in ICU mechanically ventilated patients can improve the patient's muscle strength,shorten the time of mechanical ventilation,promote the patient's recovery,reduce the occurrence of complications,and improve the patient's compliance and satisfaction.
文摘The practice of stratified English teaching is determined by the features of vocational education. In addition, it is an inexorable trend of current higher education reform, and also a fundamental demand of higher vocational education and quality-oriented education. This thesis argues for the need of stratified English teaching in high vocational colleges.
基金the financial support of the National Program on Key Basic Research Project (973 Program) of China (no. 2012CB215000)
文摘A high-density, high-flux circulating fluidized bed (CFB) riser (100 mm in ID and 10.614 m in height) was applied in a wide range of operating conditions (with solid fluxes up to 400 kg/m2s and superficial gas velocities up to 12 m/s) to examine its radial non-uniformity dynamics. The solids holdup was determined through the use of a fiber-optic probe at 11 axial levels. The results indicated that under all operating conditions, the high superficial gas velocity and low solid fluxes maintained a low radial non-uniformity index (RNI). The high-density/flux CFB riser had several unique characteristics, so that the peak of the radial solids holdup profile occurred at a position with r/R=0.8. The RNI and solids holdup at the cross-sectional position had a good logarithmic relationship at the low-density condition (with a mean solids holdup of <0.2), and the RNI decreased when the mean solids holdup exceeded 0.2. Investigation of the dynamics of stratified injection revealed that the feed ratio had an important effect on Gs and on solids holdup distribution. A novel "<" shaped axial solids holdup profile was found. Gs decreased sharply when the up-flow feed ratio exceeded 0.5, and RNI was lowest when the up-flow feed ratio was 1.
文摘The evaluation of education in the training process is important for students, and its importance is at the level of students and thecorresponding level of evaluation. Understanding the guidance and training of the middle school football team is an important partof rapidly improving the level of Chinese football. It is necessary to adapt to the development characteristics of middle schoolstudents and conduct reasonable guidance training. Plans must be strengthened to implement training programs. On the trainingschedule, we must balance learning and training, and must fully consider the growth of students. As part of a layered education,stratified evaluation has the unique advantages of basic education and secondary education. The evaluation of the students whofocus on various levels of learning. Football coaching and training requires a full display of the student's personality. The teacher'sstratified evaluation method is very important for improving students' confidence in learning, enhancing students' enthusiasm forfootball training, and promoting students' continuous improvement. This study takes the application of stratified evaluation in theteaching and training of middle school football as the research direction, and puts forward reasonable suggestions by analyzing thetraining cases of the layered evaluation.
基金The National Natural Science Foundation of China under contract No.51979095.
文摘In this paper,for the first time,we investigated the combined effect of subsurface dams and a typical stratified aquifer(two high-permeability layers with a low-permeability layer between them)on groundwater flow and salinity distribution in a tidally influenced coastal unconfined aquifer.Subsurface dams can inhibit the invasion of saltwater,and the low-permeability layer(LPL)and tide action can increase the effect of subsurface dams and the removal rate of residual saltwater.Through sensitivity analysis,it was discovered that shifting the dam location towards the inland resulted in a reduction in the effective heights of the dam.The upper saline plume contracted with increasing dam height,and the upper boundary of LPL was moved to shallower regions.And the natural removal time increased significantly with increasing dam height and the bottom boundary of LPL was moved to deeper regions.In addition,if the dam location was close to the sea boundary and the bottom boundary of LPL was moved to deeper regions,we could increase the subsurface dam height to reduce the risks of control of saltwater intrusion.This study provides us a comprehensive understanding of the complex hydrodynamics of saltwater intrusion and provides guides for the design of subsurface dams aimed at saltwater intrusion control in stratified coastal aquifers.
基金The work received the support of by National Natural Science Foundation of China(52272338)Major Project of Science and Technology Research Program of Chongqing Education Commission of China(KJZD-M202212901,KJZD-K202012903)Young Elite Scientists Sponsorship Program(2020-JCJQ-QT-005).
文摘Wax deposition in oil-water stratified flow is commonly encountered onshore and offshore oil production pipe systems,and typically reduces transportation capacity of oil.The accurate predicted model of wax deposition has becomes an indispensable approach to design effective remediation strategies.However,a reliable mechanistic model for wax deposition prediction in oil-water two-phase stratified pipe flow is lacking to validate the deposition process.In this work,a three-dimensional(axial,radial,and angular)robust wax deposit model for oil-water stratified circular pipe flow was developed.The model of formation of a gel deposit based on the first principles of rheology was developed,associated with the results obtained from hydrodynamics and heat/mass transfer simulations.The predictions for wax deposition are found to compare satisfactorily with experimental data with two different oils for single phase and four different water cuts for oil-water stratified pipe flow.It can be seen from the wax gelation mechanism that an increase in water cut can help to reduce the wall/oil-deposit interface shear stress,thereby leading to an increase in the degree of gelation as well as the deposit rate.Furthermore,a local deposit analysis in the circumferential direction was conducted,for water cut 75%and total flow rate 5 m3/h,which provided insights to understand that the thickness on pipe wall was roughly uniformly distributed locates near the top of the pipe and the nearer the position gets close to two points,where the oil-water interface contacts the inner wall,the deposition thickness quickly dropped to 0.It was attributed to the fact that a roughly uniformly thickness far away from the oil-water interface contact the inner wall resulted in the slowly changes temperature along the circumferential pipe wall wetted by oil.
基金funded by National Natural Science Foundation of China(Grant No.52074161)National Science and Technology Major Project of China(Grant No.2016ZX05065-001)+2 种基金Taishan Scholar Project of Shandong Province(Grant No.tsqn202211177)Shandong Provincial Plan for Introduction and Cultivation of Young Pioneers in Colleges and Universities(Grant No.2021-QingChuang-30613019)Natural Science Foundation of Shandong Province(Grant No.ZR2022ME173).
文摘Dynamic performance on solids flow with water in deviated tubing is essential for the reliability of pump and normal operation of horizontal and directional wells.Compared with coal-water flow in vertical tubing and sand-oil flow with high production in deviated tubing,solids deposition with water shows obvious non-symmetric distributions in deviated tubing from simulations and experiments.The mathematical model of two phase flow was developed under coupling conditions of deviated tubing,low flow rate and viscosity based on the kinetic theory of granular flow and first-order discrete scheme.The results show that solid-water stratified flow in deviated tubing can be divided into two zones of suspension bed and the moving bed throughout the flow field.The solid flowing velocity with water is negative and particles slide down at the bottom of moving bed zone.The process of solids flow with water in deviated tubing will produce pressure loss and consume the kinetic energy.The thickness of deposited layer and the flowing velocity of solids flow downward with water at the moving bed zone enhance with the decreased inlet flow rate and the increased particle size,tubing inside diameter(ID)and inclination angle.Solids are easier into suspension from the upper part of moving bed zone to suspension bed zone and more solid particles flow with water towards the tubing outlet with the increase of inlet flowing velocity.The decision is made to reduce the screen width,tubing ID and inclination angle to maintain to be greater than critical deposition velocity in order to prevent solids settling.And it provides the theoretical basis and technical reserves for solid control and offers an effective approach to enhance tubing cleaning in deviated strings.
基金This work is supported by ONR,contract N000142012315.
文摘A stratified wake has multiple flow regimes,and exhibits different behaviors in these regimes due to the competing physical effects of momentum and buoyancy.This work aims at automated classification of the weakly and the strongly stratified turbulence regimes based on information available in a full Reynolds stress model.First,we generate a direct numerical simulation database with Reynolds numbers from 10,000 to 50,000 and Froude numbers from 2 to 50.Order(100)independent realizations of temporally evolving wakes are computed to get converged statistics.Second,we train a linear logistic regression classifier with weight thresholding for automated flow regime classification.The classifier is designed to identify the physics critical to classification.Trained against data at one flow condition,the classifier is found to generalize well to other Reynolds and Froude numbers.The results show that the physics governing wake evolution is universal,and that the classifier captures that physics.
文摘This research focused on the study of heat and mass transfers in a two-phase stratified turbulent fluid flow in a geothermal pipe with chemical reaction. The derived non-linear partial differential equations governing the flow were solved using the Finite Difference Method. The effects of various physical parameters on the concentration, skin friction, heat, and mass transfers have been determined. Analysis of the results obtained indicated that the coefficient of skin friction decreased with an increase in Reynolds number and solutal Grasholf number, the rate of heat transfer increased with an increase in Eckert number, Prandtl number, and angle of inclination, and the rate of mass transfer increased with increase in Reynolds number, Chemical reaction parameter and angle of inclination. The findings would be useful to engineers in designing and maintaining geothermal pipelines more effectively.
基金Supported by the Guizhou Senior Innovative Talent Project,No.QKHPTRC-GCC[2022]041-1.
文摘BACKGROUND Transjugular intrahepatic portosystemic shunt(TIPS)has been extensively used to treat portal hypertension-associated complications,including cirrhosis.The prediction of post-TIPS prognosis is important for cirrhotic patients,as more aggressive liver transplantation is needed when the post-TIPS prognosis is poor.AIM To construct a nutrition-based model that could predict the disease progression of cirrhotic patients after TIPS implantation in a sex-dependent manner.METHODS This study retrospectively recruited cirrhotic patients undergoing TIPS implantation for analysis.Muscle quality was assessed by measuring the skeletal muscle index(SMI)by computed tomography.Multivariate Cox proportional hazard models were utilized to determine the association between SMI and disease progression in cirrhotic patients after TIPS implantation.RESULTS This study eventually included 186 cirrhotic patients receiving TIPS who were followed up for 30.5±18.8 mo.For male patients,the 30-mo survival rate was significantly lower and the probability of progressive events was higher(3.257-fold)in the low-level SMI group than in the high-level SMI group.According to the multivariate Cox analysis of male patients,SMI<32.8 was an independent risk factor for long-term adverse outcomes after TIPS implantation.A model was constructed,which involved creatinine,plasma ammonia,SMI,and acute-on-chronic liver failure and hepatic encephalopathy occurring within half a year after surgery.This model had an area under the receiver operating characteristic curve of 0.852,sensitivity of 0.926,and specificity of 0.652.According to the results of the DeLong test,this model outperformed other models(Child-Turcotte-Pugh,Model for End-Stage Liver Disease,and Freiburg index of post-TIPS survival)(P<0.05).CONCLUSION SMI is strongly associated with poor long-term outcomes in male patients with cirrhosis who underwent TIPS implantation.
文摘In this study,the damping responses of uniform soil,equi-proportional fly ash,and local soil as a single unit were investigated.The large-strain cyclic triaxial tests were performed for the specimen compacted at the desired density(95%e99%of maximum dry density).The compacted specimens were tested under the loading frequency of 0.3e1 Hz with medium confinement of 70e100 kPa.Also,the unsymmetrical behavior of the hysteresis loop was analyzed using three different damping estimation approaches,i.e.symmetric hysteresis loop(SHL),asymmetric hysteresis loop(ASHL),and the modified American Society for Testing and Materials(ASTM)method.The outcome of the study shows for fly ash,local soil,and layered soil-ash,the ASHL technique has the highest damping value,followed by ASTM and then the SHL approach.The specimens prepared under high density and subjected to high confinement show low damping values.However,the specimens tested at high frequency exhibits high damping behavior.Similarly,the damping value of fly ash determined using the SHL and ASHL methods has a similar profile and reaches a maximum at 1%shear strain value before decreasing.The composite stratified deposit exhibits more dependency on relative compaction,confining pressure,and less on loading frequency.Based on the results,it is highly recommended to use the ASHL approach,especially under large strain conditions irrespective of soil type.The maximum damping ratio of stratified deposits is always in between the damping ratio of local soil and fly ash.The damping ratio of stratified soil and local soil is slightly larger than that of the other soils,although the damping ratio of fly ash is equivalent to that of the sand and clayey soil.These results may be helpful in the accurate determination of the damping properties of the layered soil-ash system that is required in the seismic response analysis.
文摘With the advancement of the new curriculum reform,many schools have put forward the idea of combing English reading with stratified teaching.Enhancing the effectiveness of reading English picture books is an important goal that most English teachers uphold when reforming the teaching of English reading.In order to achieve this goal,it is necessary to improve the teaching methods of reading.Reading picture books is an important way to improve students5 core competencies in English.However,at present,the method of teaching reading in primary school is simple;in addition,the teaching activities are not well organized.Therefore,in order to improve students5 core competencies in English,this article points out several issues in the teaching of English picture book reading and provides some pedagogical implications for the teaching in this aspect based on the stratified teaching method and classroom observation by including Class 1,Grade 2 students from a primary school in Leshan as the research subjects.