The characteristics of the normal equation created in recovering the Earth gravity model （EGM） by least-squares （LS） adjustment from the in-situ disturbing potential is discussed in detail. It can be concluded tha...The characteristics of the normal equation created in recovering the Earth gravity model （EGM） by least-squares （LS） adjustment from the in-situ disturbing potential is discussed in detail. It can be concluded that the normal equation only depends on the orbit, and the choice of a priori gravity model has no effect on the LS solution. Therefore, the accuracy of the recovered gravity model can be accurately simulated. Starting from this point, four sets of disturbing potential along the orbit with different level of noise were simulated and were used to recover the EGM. The results show that on the current accuracy level of the accelerometer calibration, the accuracy of the EGM is not sufficient to reflect the time variability of the Earth＇s gravity field, as the dynamic method revealed.展开更多
A new non-invasive blood glucose measuring apparatus (NBGMA) made up of MSP430F149 SCM (single chip micyoco) was developed,which can measure blood glucose level (BGL) frequently,conveniently and painlessly. The hardwa...A new non-invasive blood glucose measuring apparatus (NBGMA) made up of MSP430F149 SCM (single chip micyoco) was developed,which can measure blood glucose level (BGL) frequently,conveniently and painlessly. The hardware and software of this apparatus were designed,and detecting algorithms based on conservation of energy method (COEM) were presented. According to the law of conservation of energy that the energy derived by human body equals energy consumed by metabolism,and the relationship between convection,evaporation,radiation and the BGL was established. The sensor module was designed. 20 healthy volunteers were involved in the clinical experiment. The BGL measured by an automatic biochemical analyzer (ABA) was set as the reference. Regression analysis was performed to compare the conservation of energy method with the biochemical method,using the 20 data points with blood glucose concentrations ranging from 680 to 1 100 mg/L. Reproducibility was measured for healthy fasting volunteers. The results show that the means of BGL detected by NBGMA and ANA are very close to each other,and the difference of standard deviation (SD) is 24.7 mg/L. The correlative coefficient is 0.807. The coefficient of variation (CV) is 4% at 921.6 mg/L. The resultant regression is evaluated by the Clarke error grid analysis (EGA) and all data points are included in the clinically acceptable regions (region A:100%,region B:0%). Accordingly,it is feasible to measure BGL with COEM.展开更多
Drainage canals are engineering structures widely used for debris flow mitigation.When passing through a drainage canal,debris flow usually scours the gully bed at the back of the rib sill of the drainage canal,which ...Drainage canals are engineering structures widely used for debris flow mitigation.When passing through a drainage canal,debris flow usually scours the gully bed at the back of the rib sill of the drainage canal,which leads to failure of the rib sill.Therefore,the scour depth at the back of the rib sill is an important design problem and it is related to the economic benefits of engineering and service years.To explore the law of the depth of the scour pit after debris flow through drainage canal ribs,we first proposed a formula for the calculation of the maximum scour depth at the back of a rib sill based on energy conservation.We then conducted a series of simulation experiments to test the proposed formula.The experimental results show that the scour depth,trench slope and the distance between ribs all increase with a decrease in debris flow density.We then compared the results of experiments and formula calculations.Through the testing analysis,we found that the calculation results of the conductedformula correspond with the experimental results better.Finally,taking Qipan Gully as an example,we designed the ultimate depth of a drainage canal for debris flow using the calculation formula.展开更多
To clarify the influence of the hydrofoil characteristic thickness on the distribution characteristics and mechanisms of clearance cavitation erosion risk,a large eddy simulation(LES)is conducted to study the clearanc...To clarify the influence of the hydrofoil characteristic thickness on the distribution characteristics and mechanisms of clearance cavitation erosion risk,a large eddy simulation(LES)is conducted to study the clearance cavitating flow around NACA0012 and NACA0024 hydrofoils under identical conditions.The study predicts cavitation erosion risk using three methods:The erosive power method(EPM),the improved gray level method(IGLM)and the energy conservation method(ECM).The numerical results are in good agreement with the experiment data and the ECM is applied due to its simplicity in parameter adjustment and low sensitivity.The results indicate that the characteristic thickness significantly influences the flow field,leading to variations in the position and intensity of cavitation collapse,ultimately resulting in notable differences in cavitation erosion risk distribution.The high cavitation erosion risk region on the clearance surface of NACA0012 is concentrated around the midsection,while it is concentrated in the upstream region for the NACA0024,with a lower frequency of extreme events.Tip separation vortex(TSV)cavitation is the main cause of the differences in cavitation erosion risk distribution.On the clearance surface of the NACA0012,TSV cavitation primarily collapses in the central region,whereas for the NACA0024 hydrofoil,TSV cavitation occurs only in the upstream region of the clearance surface and exhibits more stability.The differences in vorticity distribution near the clearance surface partially influence the distribution of TSV cavitation,thereby affecting the characteristics of cavitation erosion risk distribution.The larger characteristic thickness of the NACA0024 reduces the effects of the stretching term and the baroclinic torque term,weakening the effect of vorticity on TSV cavitation,resulting in more stable patterns of the TSV cavitation.展开更多
基金Funded by the National Natural Science Foundation of China （No.40274004）, and the Open Fund of Key Laboratory of Geospace Environment and Geodesy, Ministry of Education, China （No. 06-09）. The authors are grateful to Prof. CHAO Dingbo for his critical comments and also thank Dr. Dadzie very much for his proof-reading.
文摘The characteristics of the normal equation created in recovering the Earth gravity model （EGM） by least-squares （LS） adjustment from the in-situ disturbing potential is discussed in detail. It can be concluded that the normal equation only depends on the orbit, and the choice of a priori gravity model has no effect on the LS solution. Therefore, the accuracy of the recovered gravity model can be accurately simulated. Starting from this point, four sets of disturbing potential along the orbit with different level of noise were simulated and were used to recover the EGM. The results show that on the current accuracy level of the accelerometer calibration, the accuracy of the EGM is not sufficient to reflect the time variability of the Earth＇s gravity field, as the dynamic method revealed.
基金Project(07JJ6133) supported by the Natural Science Foundation of Hunan Province, China
文摘A new non-invasive blood glucose measuring apparatus (NBGMA) made up of MSP430F149 SCM (single chip micyoco) was developed,which can measure blood glucose level (BGL) frequently,conveniently and painlessly. The hardware and software of this apparatus were designed,and detecting algorithms based on conservation of energy method (COEM) were presented. According to the law of conservation of energy that the energy derived by human body equals energy consumed by metabolism,and the relationship between convection,evaporation,radiation and the BGL was established. The sensor module was designed. 20 healthy volunteers were involved in the clinical experiment. The BGL measured by an automatic biochemical analyzer (ABA) was set as the reference. Regression analysis was performed to compare the conservation of energy method with the biochemical method,using the 20 data points with blood glucose concentrations ranging from 680 to 1 100 mg/L. Reproducibility was measured for healthy fasting volunteers. The results show that the means of BGL detected by NBGMA and ANA are very close to each other,and the difference of standard deviation (SD) is 24.7 mg/L. The correlative coefficient is 0.807. The coefficient of variation (CV) is 4% at 921.6 mg/L. The resultant regression is evaluated by the Clarke error grid analysis (EGA) and all data points are included in the clinically acceptable regions (region A:100%,region B:0%). Accordingly,it is feasible to measure BGL with COEM.
基金financially supported by the key Projects of the Chinese Academy of Sciences (Grant No.KZZD-EW-05-01-04)the National Science and Technology Support Program (Grant No.2012BAC06B02)the sub-program of Science and technology research and development plan from China Railway (Grant No.2014G004-A-5)
文摘Drainage canals are engineering structures widely used for debris flow mitigation.When passing through a drainage canal,debris flow usually scours the gully bed at the back of the rib sill of the drainage canal,which leads to failure of the rib sill.Therefore,the scour depth at the back of the rib sill is an important design problem and it is related to the economic benefits of engineering and service years.To explore the law of the depth of the scour pit after debris flow through drainage canal ribs,we first proposed a formula for the calculation of the maximum scour depth at the back of a rib sill based on energy conservation.We then conducted a series of simulation experiments to test the proposed formula.The experimental results show that the scour depth,trench slope and the distance between ribs all increase with a decrease in debris flow density.We then compared the results of experiments and formula calculations.Through the testing analysis,we found that the calculation results of the conductedformula correspond with the experimental results better.Finally,taking Qipan Gully as an example,we designed the ultimate depth of a drainage canal for debris flow using the calculation formula.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.52479085,12472245).
文摘To clarify the influence of the hydrofoil characteristic thickness on the distribution characteristics and mechanisms of clearance cavitation erosion risk,a large eddy simulation(LES)is conducted to study the clearance cavitating flow around NACA0012 and NACA0024 hydrofoils under identical conditions.The study predicts cavitation erosion risk using three methods:The erosive power method(EPM),the improved gray level method(IGLM)and the energy conservation method(ECM).The numerical results are in good agreement with the experiment data and the ECM is applied due to its simplicity in parameter adjustment and low sensitivity.The results indicate that the characteristic thickness significantly influences the flow field,leading to variations in the position and intensity of cavitation collapse,ultimately resulting in notable differences in cavitation erosion risk distribution.The high cavitation erosion risk region on the clearance surface of NACA0012 is concentrated around the midsection,while it is concentrated in the upstream region for the NACA0024,with a lower frequency of extreme events.Tip separation vortex(TSV)cavitation is the main cause of the differences in cavitation erosion risk distribution.On the clearance surface of the NACA0012,TSV cavitation primarily collapses in the central region,whereas for the NACA0024 hydrofoil,TSV cavitation occurs only in the upstream region of the clearance surface and exhibits more stability.The differences in vorticity distribution near the clearance surface partially influence the distribution of TSV cavitation,thereby affecting the characteristics of cavitation erosion risk distribution.The larger characteristic thickness of the NACA0024 reduces the effects of the stretching term and the baroclinic torque term,weakening the effect of vorticity on TSV cavitation,resulting in more stable patterns of the TSV cavitation.
