Objective:To investigate the predictive value of diaphragm thickening fraction(DTF)combined with cough peak expiratory flow(CPEF)on the success rate of weaning from mechanical ventilation.Methods:The clinical data of ...Objective:To investigate the predictive value of diaphragm thickening fraction(DTF)combined with cough peak expiratory flow(CPEF)on the success rate of weaning from mechanical ventilation.Methods:The clinical data of patients undergoing invasive mechanical ventilation via oral endotracheal intubation in the ICU of our hospital from January 2022 to December 2023 were studied.All patients underwent a 30-minute spontaneous breathing trial(SBT)using low-level pressure support ventilation(PSV)after meeting the clinical weaning screening criteria.Among them,150 patients who met the clinical weaning criteria were weaned from the ventilator.They were divided into a successful weaning group(n=100)and a failed weaning group(n=50)based on the weaning outcome.Clinical data,including age,gender,APACHE II score,duration of mechanical ventilation,DTF,and CPEF,were collected from 150 patients.The differences in clinical data between the two groups were compared,and the correlation between DTF,CPEF,and the success rate of weaning was analyzed.Results:There were no significant differences between the two groups in gender ratio(χ^(2)=0.884,P=0.347>0.05),age(t=0.350,P=0.727>0.05),and APACHE II score(t=1.295,P=0.197>0.05),but there was a significant difference in the duration of mechanical ventilation(t=3.766,P<0.001).The DTF and CPEF values in the successful weaning group were significantly higher than those in the failed weaning group(P<0.05).ROC curves were drawn to predict the weaning results using DTF,CPEF,and the combination of DTF and CPEF.The results showed that the specificity of the combination of DTF and CPEF was comparable to that of either metric alone,but the sensitivity and AUC were significantly higher than those of either metric alone.Conclusion:The combination of DTF and CPEF can be used as an effective indicator to evaluate the weaning efficacy of mechanically ventilated patients,which has important clinical significance for guiding clinical weaning treatment,improving the success rate of weaning,reducing the incidence of ventilator-associated pneumonia,and shortening the length of hospital stay.展开更多
Spring snowmelt peak flow （SSPF） can cause serious damage. Precipitation as rainfall directly contributes to the SSPF and influences the characteristics of the SSPF, while temperature indirectly impacts the SSPF by ...Spring snowmelt peak flow （SSPF） can cause serious damage. Precipitation as rainfall directly contributes to the SSPF and influences the characteristics of the SSPF, while temperature indirectly impacts the SSPF by shaping snowmelt rate and determining the soil frozen state which partitions snowmelt water into surface runoff and soil infiltration water in spring. It is necessary to identify the important and significant paths of climatic factors influencing the SSPF and provide estimates of the magnitude and significance of hypothesized causal connections between climatic factors and the SSPF. This study used path analysis with a selection of five factors - the antecedent precipitation index （API）, spring precipitation （SP）, winter precipitation as snowfall （WS）, 〈0℃ temperature accumulation in winter （[ATNI）, and average 〉0℃temperature accumulation in spring （AT） - to analyze their influences on the SSPF in the Kaidu River in Xinjiang, China. The results show that {ATN}, AT and WS have a significant correlation with the SSPF, while API and SP do not show a significant correlation. AT and WS directly influence the SSPF, while as the influence of[ATN] on SSPF is indirect through WS and AT. The indirect influence of [ATN[ on SSPF through WS accounts for 69% of the total influence of [ATN] on SSPF. Compared to the multiple linear regression method, path analysis provides additional valuable information, including influencing paths from independent variables to the dependent variable as well as direct and indirect impacts of external variables on the internal variable. This information can help improve the description of snow melt and spring runoff in hydrologic models as well as the planning and management of water resources.展开更多
The hot deformation behavior and the microstructure characteristics of alloy 617 and alloy C-HRA-2 were compared and analyzed.The removal of Al and Ti elements has a significant change in the hot deformation of the al...The hot deformation behavior and the microstructure characteristics of alloy 617 and alloy C-HRA-2 were compared and analyzed.The removal of Al and Ti elements has a significant change in the hot deformation of the alloy,and there are two opposite effects on the flow stress before and after recrystallization.The results show that the removal of Al and Ti elements increases the flow stress of the alloy under high temperature or low strain rate deformation conditions.This is mainly due to the increase in the stacking fault energy of the alloy so that the alloy contains a higher twin boundary fraction after dynamic recrystallization(DRX).However,before DRX occurs,that is,at low temperature and high strain rate,the flow stress of this alloy is relatively reduced.This is due to the reduction in Peierls-Nabarro stress,making the alloy more prone to dislocation slip.展开更多
Accurate flood prediction is an important tool for risk management and hydraulic works design on a watershed scale. The objective of this study was to calibrate and validate 24 linear and non-linear regression models,...Accurate flood prediction is an important tool for risk management and hydraulic works design on a watershed scale. The objective of this study was to calibrate and validate 24 linear and non-linear regression models, using only upstream data to estimate real-time downstream flooding. Four critical downstream estimation points in the Mataquito and Maule river basins located in central Chile were selected to estimate peak flows using data from one, two, or three upstream stations. More than one thousand paper-based storm hydrographs were manually analyzed for rainfall events that occurred between 1999 and 2006, in order to determine the best models for predicting downstream peak flow. The Peak Flow Index (IQP) (defined as the quotient between upstream and downstream data) and the Transit Times (TT) between upstream and downstream points were also obtained and analyzed for each river basin. The Coefficients of Determination (R2), the Standard Error of the Estimate (SEE), and the Bland-Altman test (ACBA) were used to calibrate and validate the best selected model at each basin. Despite the high variability observed in peak flow data, the developed models were able to accurately estimate downstream peak flows using only upstream flow data.展开更多
Piezocatalysis is an emerging approach for degrading organic dye,However,the limited availability of ultrasonic resources in nature restricts its practical application.Our proposed peak flow kinetic energy piezocataly...Piezocatalysis is an emerging approach for degrading organic dye,However,the limited availability of ultrasonic resources in nature restricts its practical application.Our proposed peak flow kinetic energy piezocatalytic strategy,based on a "waterfall flow" model,aims to simulate the piezocatalytic degradation of pollutants in nature.This innovative strategy can enhance degradation eficiency by adjusting the flow rate and drop height.When 140 mL of rhodamine B(RhB)dye solution flows at a rate of 1000mL/min from a height of 48 cm and impacts a 3 cm diameter BaTiO_(3) nanowires/PVDF piezoelectric composite film,a degradation rate of 90%can be achieved within 120 min.This rapid degradation is primarily attributed to the efficient conversion of kinetic energy into impact force as the water falls,which triggers the generation of piezopotential in the composite film.This,in turn,drives the separation and transmission of electron-hole pairs,leading to the promotion of reactive oxygen species(ROS)generation and facilitating fast organic dye degradation.The pulsating nature of the impact force ensures a continuous generation of ROS.This approach is poised to advance piezocatalysis for the degradation of organic dyes in natural environments and presents a novel method for wastewater treatment.展开更多
Background:Pulmonary hypertension(PH)is a life-threatening condition that can be triggered by pulmonary thromboembolism(PTE),which causes abrupt increases in pulmonary artery pressure and resistance.Although Doppler e...Background:Pulmonary hypertension(PH)is a life-threatening condition that can be triggered by pulmonary thromboembolism(PTE),which causes abrupt increases in pulmonary artery pressure and resistance.Although Doppler echocardiography is a useful screening tool,its ability to accurately reflect rapid hemodynamic changes during acute PTE remains limited.The Flowire catheter allows for real-time assessment of intravascular flow and may offer better insight into these changes.Aims:The aims were to investigate changes in pulmonary artery hemodynamics measured using a Flowire catheter and to validate the accuracy of Doppler echocardiography in assessing these changes in dogs with acute pulmonary thromboembolism(PTE).Methods:Hemodynamic and echocardiographic data were obtained from 10 anesthetized female beagles using a Flowire catheter and echocardiography at three preload conditions:baseline,bolus loading,and an acute pulmonary hypertension state induced by a 300-μm dextran microsphere injection.Results:With increases in pulmonary artery pressure and pulmonary vascular resistance,the proximal and distal pulmonary artery flow peak measured using the Flowire catheter significantly decreased during the acute pulmonary hypertension period.Echocardiography did not accurately capture these hemodynamic changes and tended to overestimate pulmonary artery flow peak in the distal pulmonary artery.Conclusion:Doppler echocardiography has limitations in accurately reflecting complex hemodynamic changes during acute PTE.In contrast,Flowire catheterization provides additional and precise local hemodynamic information.展开更多
Understanding the amount of instantaneous peak flow in watersheds is one of the most important factors that plays important role in planning and designing of projects related to water and river engineering. The purpos...Understanding the amount of instantaneous peak flow in watersheds is one of the most important factors that plays important role in planning and designing of projects related to water and river engineering. The purpose of this study is to compare the efficiency of artificial neural network and empirical methods for estimating instantaneous peak flow in Kharestan Watershed located northwest of Fars Province, Iran. For this purpose, 25 years of daily peak and instantaneous peak flow of Jamal Beig Hydrometric Station was considered. Then the estimation was done based on empirical methods including Fuller, Sangal and Fill-Steiner and artificial neural network and were compared based on RMSE and R2 . Results showed that estimation of artificial neural network is more accurate than empirical methods with RMSE = 13.710 and R2=0.942 which indicated the lower errors of artificial neural network method compared with empirical methods.展开更多
Objective:This study aimed to determine the effect of combined diaphragmatic breathing and therapeutic walking exercise on peak expiratory flow in asthma patients.Methods:The research design used a quasi-experiment no...Objective:This study aimed to determine the effect of combined diaphragmatic breathing and therapeutic walking exercise on peak expiratory flow in asthma patients.Methods:The research design used a quasi-experiment nonequivalent pretest and posttest design.The research sample contained 38 respondents divided into intervention and control groups,selected by simple random sampling.The control group received standard drug therapy,while the intervention group received standard drug therapy and a combination of diaphragmatic breathing and therapeutic walking exercise for 2 weeks.This exercise was carried out in the morning,6 times a week,with 5 diaphragmatic breathing and exhalations per exercise.After that,a 1-min break was followed by a therapeutic walking exercise of 5–15 min,with an increased duration.Both groups measured the peak expiratory flow before and after the intervention using a peak flow meter.The data analysis used central tendency and t-test.Results:The results showed that the mean peak expiratory flow in the intervention group was 306.84,while in the control group,it was 232.63,with the value of the t-test being-14.17(P<0.0001).Conclusions:Diaphragmatic breathing and therapeutic walking exercise significantly increased the peak expiratory flow in asthma patients.展开更多
Peak discharge plays an important role in triggering channelized debris flows.The rainfall regimes and rainfall characteristics have been demonstrated to have important influences on peak discharge.In order to explore...Peak discharge plays an important role in triggering channelized debris flows.The rainfall regimes and rainfall characteristics have been demonstrated to have important influences on peak discharge.In order to explore the relationship between rainfall regimes and peak discharge,a measuring system was placed at the outlet of a small,debris flow-prone catchment.The facility consisted of an approximately rectangular stilling basin,ending with a sharp-crested weir.Six runoff events were recorded which provided a unique opportunity for characterizing the hydrological response of the debris flow-prone catchment.Then,a rainfall–runoff model was tested against the flow discharge measurements to have a deep understanding of hydrological response.Based on the calibrated rainfall-runoff model,twelve different artificially set rainfall patterns were regarded as the input parameters to investigate the effect of rainfall regimes on peak discharge.The results show that the rainfall patterns have a significant effect on peak discharge.The rainfall regimes which have higher peak rainfall intensity and peak rainfall point occur at the later part of rainfall process are easy to generate larger peak discharge in the condition of the same cumulative rainfall and duration.Then,in order to explore the relationship between rainfall characteristics and peak discharge under different cumulative precipitation and different duration,167 measured rainfall events were also collected.On the basis of rainfall depth,rainfall duration,and maximum hourly intensity,all the rainfall events were classified into four categories by using K-mean clustering.Rainfall regime 1 was composed of rainfall events with a moderate mean P(precipitation),a moderate D(duration),and a moderate I60(maximum hourly intensity).Rainfall regime 2 was the group of rainfall events with a high mean P,long D.Rainfall regime 3,however,had a low P and a long D.The characteristic of Rainfall regime 4 was high I60 and short duration with large P.The results show that the rainfall regime 2 and 4 are easier to generate peak discharge as the rainfall intensity plays an important role in generating peak discharge.The results in this study have implications for improving peak discharge prediction accuracy in debris flow gully.展开更多
Background: A Randomized Controlled Trial (RCT) has been elaborated where goal directed fluid and hemodynamic therapy (GDFHT) will be realized with trans-thoracic echocardiographic aortic blood flow peak velocity vari...Background: A Randomized Controlled Trial (RCT) has been elaborated where goal directed fluid and hemodynamic therapy (GDFHT) will be realized with trans-thoracic echocardiographic aortic blood flow peak velocity variation (ΔVpeak) and distance minute (DM) to guide fluid therapy and hemodynamics in high risk pediatric surgical patients. This RCT will clarify the impact of GDFHT with ΔVpeak and DM on postoperative outcome in terms of morbidity, length of stay in the intensive care unit (LOSICU), length of mechanical ventilation (LMV) and length of hospital stay (LOS) in children. To determine values of ΔVpeak, DM and VTI predictive of these postoperative outcomes, an observational pilot study will be realized. This pilot study is described here. The primary objective of this study is to determine values of ΔVpeak, DM and ITV predictive of postoperative outcome in children in terms of morbidity. The secondary objectives are to determine values of ΔVpeak, DM and ITV predictive of LOSICU, LMV, LOS, intraoperative, postoperative fluid administration and vasoactive-inotropic therapy. Methods: 500 - 1000 children aged less than 18 years will be included prospectively. Statistic analysis will be realized with XLSTAT 2019.4.2 software or plus. Results and Conclusions: This trial protocol will determine values of ΔVpeak, DM and ITV with echocardiography predictive of postoperative outcome in children.展开更多
文摘Objective:To investigate the predictive value of diaphragm thickening fraction(DTF)combined with cough peak expiratory flow(CPEF)on the success rate of weaning from mechanical ventilation.Methods:The clinical data of patients undergoing invasive mechanical ventilation via oral endotracheal intubation in the ICU of our hospital from January 2022 to December 2023 were studied.All patients underwent a 30-minute spontaneous breathing trial(SBT)using low-level pressure support ventilation(PSV)after meeting the clinical weaning screening criteria.Among them,150 patients who met the clinical weaning criteria were weaned from the ventilator.They were divided into a successful weaning group(n=100)and a failed weaning group(n=50)based on the weaning outcome.Clinical data,including age,gender,APACHE II score,duration of mechanical ventilation,DTF,and CPEF,were collected from 150 patients.The differences in clinical data between the two groups were compared,and the correlation between DTF,CPEF,and the success rate of weaning was analyzed.Results:There were no significant differences between the two groups in gender ratio(χ^(2)=0.884,P=0.347>0.05),age(t=0.350,P=0.727>0.05),and APACHE II score(t=1.295,P=0.197>0.05),but there was a significant difference in the duration of mechanical ventilation(t=3.766,P<0.001).The DTF and CPEF values in the successful weaning group were significantly higher than those in the failed weaning group(P<0.05).ROC curves were drawn to predict the weaning results using DTF,CPEF,and the combination of DTF and CPEF.The results showed that the specificity of the combination of DTF and CPEF was comparable to that of either metric alone,but the sensitivity and AUC were significantly higher than those of either metric alone.Conclusion:The combination of DTF and CPEF can be used as an effective indicator to evaluate the weaning efficacy of mechanically ventilated patients,which has important clinical significance for guiding clinical weaning treatment,improving the success rate of weaning,reducing the incidence of ventilator-associated pneumonia,and shortening the length of hospital stay.
基金financially supported by the Project of State Key Basic R & D Program of China (973 Program, Grant No. 2010CB951002)the key deployment project of Chinese Academy of Sciences (Grant No. KZZD-EW-12-2)Chinese Academy of Sciences Visiting Professorship for Senior International Scientists (Grant No. 2011T2Z40)
文摘Spring snowmelt peak flow （SSPF） can cause serious damage. Precipitation as rainfall directly contributes to the SSPF and influences the characteristics of the SSPF, while temperature indirectly impacts the SSPF by shaping snowmelt rate and determining the soil frozen state which partitions snowmelt water into surface runoff and soil infiltration water in spring. It is necessary to identify the important and significant paths of climatic factors influencing the SSPF and provide estimates of the magnitude and significance of hypothesized causal connections between climatic factors and the SSPF. This study used path analysis with a selection of five factors - the antecedent precipitation index （API）, spring precipitation （SP）, winter precipitation as snowfall （WS）, 〈0℃ temperature accumulation in winter （[ATNI）, and average 〉0℃temperature accumulation in spring （AT） - to analyze their influences on the SSPF in the Kaidu River in Xinjiang, China. The results show that {ATN}, AT and WS have a significant correlation with the SSPF, while API and SP do not show a significant correlation. AT and WS directly influence the SSPF, while as the influence of[ATN] on SSPF is indirect through WS and AT. The indirect influence of [ATN[ on SSPF through WS accounts for 69% of the total influence of [ATN] on SSPF. Compared to the multiple linear regression method, path analysis provides additional valuable information, including influencing paths from independent variables to the dependent variable as well as direct and indirect impacts of external variables on the internal variable. This information can help improve the description of snow melt and spring runoff in hydrologic models as well as the planning and management of water resources.
基金This work was supported by National Natural Science Foundation of China(Grant No.52104375)Natural Science Foundation of Jiangsu Province(Grant No.BK20201066)+1 种基金National Key Research and Development Program of China(Grant No.2017YFB0305203)Basic Science(Natural Science)Research of Institution of Higher Education of Jiangsu Province(Grant No.22KJA460010).
文摘The hot deformation behavior and the microstructure characteristics of alloy 617 and alloy C-HRA-2 were compared and analyzed.The removal of Al and Ti elements has a significant change in the hot deformation of the alloy,and there are two opposite effects on the flow stress before and after recrystallization.The results show that the removal of Al and Ti elements increases the flow stress of the alloy under high temperature or low strain rate deformation conditions.This is mainly due to the increase in the stacking fault energy of the alloy so that the alloy contains a higher twin boundary fraction after dynamic recrystallization(DRX).However,before DRX occurs,that is,at low temperature and high strain rate,the flow stress of this alloy is relatively reduced.This is due to the reduction in Peierls-Nabarro stress,making the alloy more prone to dislocation slip.
文摘Accurate flood prediction is an important tool for risk management and hydraulic works design on a watershed scale. The objective of this study was to calibrate and validate 24 linear and non-linear regression models, using only upstream data to estimate real-time downstream flooding. Four critical downstream estimation points in the Mataquito and Maule river basins located in central Chile were selected to estimate peak flows using data from one, two, or three upstream stations. More than one thousand paper-based storm hydrographs were manually analyzed for rainfall events that occurred between 1999 and 2006, in order to determine the best models for predicting downstream peak flow. The Peak Flow Index (IQP) (defined as the quotient between upstream and downstream data) and the Transit Times (TT) between upstream and downstream points were also obtained and analyzed for each river basin. The Coefficients of Determination (R2), the Standard Error of the Estimate (SEE), and the Bland-Altman test (ACBA) were used to calibrate and validate the best selected model at each basin. Despite the high variability observed in peak flow data, the developed models were able to accurately estimate downstream peak flows using only upstream flow data.
基金supported by the National Natural Science Foundation of China(Grant No.52162018)the Science Fund for Distinguished Young Scholars of Jiangxi Province(Grant No.20224ACB214007).
文摘Piezocatalysis is an emerging approach for degrading organic dye,However,the limited availability of ultrasonic resources in nature restricts its practical application.Our proposed peak flow kinetic energy piezocatalytic strategy,based on a "waterfall flow" model,aims to simulate the piezocatalytic degradation of pollutants in nature.This innovative strategy can enhance degradation eficiency by adjusting the flow rate and drop height.When 140 mL of rhodamine B(RhB)dye solution flows at a rate of 1000mL/min from a height of 48 cm and impacts a 3 cm diameter BaTiO_(3) nanowires/PVDF piezoelectric composite film,a degradation rate of 90%can be achieved within 120 min.This rapid degradation is primarily attributed to the efficient conversion of kinetic energy into impact force as the water falls,which triggers the generation of piezopotential in the composite film.This,in turn,drives the separation and transmission of electron-hole pairs,leading to the promotion of reactive oxygen species(ROS)generation and facilitating fast organic dye degradation.The pulsating nature of the impact force ensures a continuous generation of ROS.This approach is poised to advance piezocatalysis for the degradation of organic dyes in natural environments and presents a novel method for wastewater treatment.
基金Japan Society for the Promotion of Science,Grant/Award Number:JSPS KAKENHI 24K18010。
文摘Background:Pulmonary hypertension(PH)is a life-threatening condition that can be triggered by pulmonary thromboembolism(PTE),which causes abrupt increases in pulmonary artery pressure and resistance.Although Doppler echocardiography is a useful screening tool,its ability to accurately reflect rapid hemodynamic changes during acute PTE remains limited.The Flowire catheter allows for real-time assessment of intravascular flow and may offer better insight into these changes.Aims:The aims were to investigate changes in pulmonary artery hemodynamics measured using a Flowire catheter and to validate the accuracy of Doppler echocardiography in assessing these changes in dogs with acute pulmonary thromboembolism(PTE).Methods:Hemodynamic and echocardiographic data were obtained from 10 anesthetized female beagles using a Flowire catheter and echocardiography at three preload conditions:baseline,bolus loading,and an acute pulmonary hypertension state induced by a 300-μm dextran microsphere injection.Results:With increases in pulmonary artery pressure and pulmonary vascular resistance,the proximal and distal pulmonary artery flow peak measured using the Flowire catheter significantly decreased during the acute pulmonary hypertension period.Echocardiography did not accurately capture these hemodynamic changes and tended to overestimate pulmonary artery flow peak in the distal pulmonary artery.Conclusion:Doppler echocardiography has limitations in accurately reflecting complex hemodynamic changes during acute PTE.In contrast,Flowire catheterization provides additional and precise local hemodynamic information.
文摘Understanding the amount of instantaneous peak flow in watersheds is one of the most important factors that plays important role in planning and designing of projects related to water and river engineering. The purpose of this study is to compare the efficiency of artificial neural network and empirical methods for estimating instantaneous peak flow in Kharestan Watershed located northwest of Fars Province, Iran. For this purpose, 25 years of daily peak and instantaneous peak flow of Jamal Beig Hydrometric Station was considered. Then the estimation was done based on empirical methods including Fuller, Sangal and Fill-Steiner and artificial neural network and were compared based on RMSE and R2 . Results showed that estimation of artificial neural network is more accurate than empirical methods with RMSE = 13.710 and R2=0.942 which indicated the lower errors of artificial neural network method compared with empirical methods.
文摘Objective:This study aimed to determine the effect of combined diaphragmatic breathing and therapeutic walking exercise on peak expiratory flow in asthma patients.Methods:The research design used a quasi-experiment nonequivalent pretest and posttest design.The research sample contained 38 respondents divided into intervention and control groups,selected by simple random sampling.The control group received standard drug therapy,while the intervention group received standard drug therapy and a combination of diaphragmatic breathing and therapeutic walking exercise for 2 weeks.This exercise was carried out in the morning,6 times a week,with 5 diaphragmatic breathing and exhalations per exercise.After that,a 1-min break was followed by a therapeutic walking exercise of 5–15 min,with an increased duration.Both groups measured the peak expiratory flow before and after the intervention using a peak flow meter.The data analysis used central tendency and t-test.Results:The results showed that the mean peak expiratory flow in the intervention group was 306.84,while in the control group,it was 232.63,with the value of the t-test being-14.17(P<0.0001).Conclusions:Diaphragmatic breathing and therapeutic walking exercise significantly increased the peak expiratory flow in asthma patients.
基金financially supported by the National Natural Science Foundation of China (Grant No. 41772276)Key R&D project of Zhejiang Province (Grant No. 2017C03006)China Postdoctoral Science Foundation (Grant No. 2019M652083)
文摘Peak discharge plays an important role in triggering channelized debris flows.The rainfall regimes and rainfall characteristics have been demonstrated to have important influences on peak discharge.In order to explore the relationship between rainfall regimes and peak discharge,a measuring system was placed at the outlet of a small,debris flow-prone catchment.The facility consisted of an approximately rectangular stilling basin,ending with a sharp-crested weir.Six runoff events were recorded which provided a unique opportunity for characterizing the hydrological response of the debris flow-prone catchment.Then,a rainfall–runoff model was tested against the flow discharge measurements to have a deep understanding of hydrological response.Based on the calibrated rainfall-runoff model,twelve different artificially set rainfall patterns were regarded as the input parameters to investigate the effect of rainfall regimes on peak discharge.The results show that the rainfall patterns have a significant effect on peak discharge.The rainfall regimes which have higher peak rainfall intensity and peak rainfall point occur at the later part of rainfall process are easy to generate larger peak discharge in the condition of the same cumulative rainfall and duration.Then,in order to explore the relationship between rainfall characteristics and peak discharge under different cumulative precipitation and different duration,167 measured rainfall events were also collected.On the basis of rainfall depth,rainfall duration,and maximum hourly intensity,all the rainfall events were classified into four categories by using K-mean clustering.Rainfall regime 1 was composed of rainfall events with a moderate mean P(precipitation),a moderate D(duration),and a moderate I60(maximum hourly intensity).Rainfall regime 2 was the group of rainfall events with a high mean P,long D.Rainfall regime 3,however,had a low P and a long D.The characteristic of Rainfall regime 4 was high I60 and short duration with large P.The results show that the rainfall regime 2 and 4 are easier to generate peak discharge as the rainfall intensity plays an important role in generating peak discharge.The results in this study have implications for improving peak discharge prediction accuracy in debris flow gully.
文摘Background: A Randomized Controlled Trial (RCT) has been elaborated where goal directed fluid and hemodynamic therapy (GDFHT) will be realized with trans-thoracic echocardiographic aortic blood flow peak velocity variation (ΔVpeak) and distance minute (DM) to guide fluid therapy and hemodynamics in high risk pediatric surgical patients. This RCT will clarify the impact of GDFHT with ΔVpeak and DM on postoperative outcome in terms of morbidity, length of stay in the intensive care unit (LOSICU), length of mechanical ventilation (LMV) and length of hospital stay (LOS) in children. To determine values of ΔVpeak, DM and VTI predictive of these postoperative outcomes, an observational pilot study will be realized. This pilot study is described here. The primary objective of this study is to determine values of ΔVpeak, DM and ITV predictive of postoperative outcome in children in terms of morbidity. The secondary objectives are to determine values of ΔVpeak, DM and ITV predictive of LOSICU, LMV, LOS, intraoperative, postoperative fluid administration and vasoactive-inotropic therapy. Methods: 500 - 1000 children aged less than 18 years will be included prospectively. Statistic analysis will be realized with XLSTAT 2019.4.2 software or plus. Results and Conclusions: This trial protocol will determine values of ΔVpeak, DM and ITV with echocardiography predictive of postoperative outcome in children.
