Asymptotic analysis is conducted for outwardly propagating spherical flames with large activation energy. The spherical flame structure consists of the preheat zone, reaction zone, and equilibrium zone. Analytical sol...Asymptotic analysis is conducted for outwardly propagating spherical flames with large activation energy. The spherical flame structure consists of the preheat zone, reaction zone, and equilibrium zone. Analytical solutions are separately obtained in these three zones and then asymp- totically matched. In the asymptotic analysis, we derive a correlation describing the spherical flame temperature and propagation speed changing with the flame radius. This cor- relation is compared with previous results derived in the limit of infinite value of activation energy. Based on this correla- tion, the properties of spherical flame propagation are inves- tigated and the effects of Lewis number on spherical flame propagation speed and extinction stretch rate are assessed. Moreover, the accuracy and performance of different mod- els used in the spherical flame method are examined. It is found that in order to get accurate laminar flame speed and Markstein length, non-linear models should be used.展开更多
Increasing bacteria levels in the Lower Neches River caused by Hurricane Harvey has been of a serious concern.This study is to analyze the historical water sampling measurements and real-time water quality data collec...Increasing bacteria levels in the Lower Neches River caused by Hurricane Harvey has been of a serious concern.This study is to analyze the historical water sampling measurements and real-time water quality data collected with wireless sensors to monitor and evaluate water quality under different hydrological and hydraulic conditions.The statistical and Pearson correlation analysis on historical water samples determines that alkalinity,chloride,hardness,conductivity,and pH are highly correlated,and they decrease with increasing flow rate due to dilution.The flow rate has positive correlations with Escherichia coli,total suspended solids,and turbidity,which demonstrates that runoff is one of the causes of the elevated bacteria and sediment loadings in the river.The correlation between E.coli and turbidity indicates that turbidity greater than 45 nephelometric turbidity units in the Neches River can serve as a proxy for E.coli to indicate the bacterial outbreak.A series of statistical tools and an innovative two-layer data smoothing filter are developed to detect outliers,fill missing values,and filter spikes of the sensor measurements.The correlation analysis on the sensor data illustrates that the elevated sediment/bacteria/algae in the river is either caused by the first flush rain and heavy rain events in December to March or practices of land use and land cover.Therefore,utilizing sensor measurements along with rainfall and discharge data is recommended to monitor and evaluate water quality,then in turn to provide early alerts on water resources management decisions.展开更多
Planetary gear trains are widely applied in various transmission units.Whether strengths of all gears are accurately calculated or not can affect reliability of the entire system significantly.Strength calculation met...Planetary gear trains are widely applied in various transmission units.Whether strengths of all gears are accurately calculated or not can affect reliability of the entire system significantly.Strength calculation method for planetary gear trains usually follows the method for cylindrical gears,in which the worst meshing positions for both contact stress and bending stress cannot be determined precisely,and calculation results tend to be conservative.To overcome these shortcomings,a kinematics analysis for a planetary gear train is firstly performed,in which the influence of relative speed is investigated.Then the finite element strength analysis of a planetary gear train based on its transient meshing properties is carried out in ANSYS.Time–history curves of contact and bending stresses of sun gear,planetary gears and ring gear are respectively obtained.Also the accurate moment and its corresponding position of the maximum stress are precisely determined.Finally,calculation results of finite element method(FEM)and traditional method are compared in order to verify the effectiveness.Simulation and comparison show the stability of the proposed method in this paper.Researches in this paper establish the foundations for fatigue analysis and optimization for a planetary gear train.展开更多
Discusses the symplectic integration of separable Hamiltonian ordinary and partial differential equations (PDE). Results of a von Neumann analysis; Spectra of linearized Hamiltonian PDEs.
基金supported by the National Natural Science Foundation of China (50976003,51136005)Doctoral Fund of Ministry of Education of China (20100001120003)
文摘Asymptotic analysis is conducted for outwardly propagating spherical flames with large activation energy. The spherical flame structure consists of the preheat zone, reaction zone, and equilibrium zone. Analytical solutions are separately obtained in these three zones and then asymp- totically matched. In the asymptotic analysis, we derive a correlation describing the spherical flame temperature and propagation speed changing with the flame radius. This cor- relation is compared with previous results derived in the limit of infinite value of activation energy. Based on this correla- tion, the properties of spherical flame propagation are inves- tigated and the effects of Lewis number on spherical flame propagation speed and extinction stretch rate are assessed. Moreover, the accuracy and performance of different mod- els used in the spherical flame method are examined. It is found that in order to get accurate laminar flame speed and Markstein length, non-linear models should be used.
基金supported by Center for Resiliency(CfR)at Lamar University(Grant No.22PSSO1).
文摘Increasing bacteria levels in the Lower Neches River caused by Hurricane Harvey has been of a serious concern.This study is to analyze the historical water sampling measurements and real-time water quality data collected with wireless sensors to monitor and evaluate water quality under different hydrological and hydraulic conditions.The statistical and Pearson correlation analysis on historical water samples determines that alkalinity,chloride,hardness,conductivity,and pH are highly correlated,and they decrease with increasing flow rate due to dilution.The flow rate has positive correlations with Escherichia coli,total suspended solids,and turbidity,which demonstrates that runoff is one of the causes of the elevated bacteria and sediment loadings in the river.The correlation between E.coli and turbidity indicates that turbidity greater than 45 nephelometric turbidity units in the Neches River can serve as a proxy for E.coli to indicate the bacterial outbreak.A series of statistical tools and an innovative two-layer data smoothing filter are developed to detect outliers,fill missing values,and filter spikes of the sensor measurements.The correlation analysis on the sensor data illustrates that the elevated sediment/bacteria/algae in the river is either caused by the first flush rain and heavy rain events in December to March or practices of land use and land cover.Therefore,utilizing sensor measurements along with rainfall and discharge data is recommended to monitor and evaluate water quality,then in turn to provide early alerts on water resources management decisions.
基金This work is supported in part by National Natural Science Fund(Grant No.51375282)Program for Changjiang Scholars and Innovative Research Team in University(Grant No.IRT1266)Special funds for Cultivation of Taishan Scholars and Postgraduate Innovation Fund of Shandong University of Science&Technology(Grant No.YC140314).
文摘Planetary gear trains are widely applied in various transmission units.Whether strengths of all gears are accurately calculated or not can affect reliability of the entire system significantly.Strength calculation method for planetary gear trains usually follows the method for cylindrical gears,in which the worst meshing positions for both contact stress and bending stress cannot be determined precisely,and calculation results tend to be conservative.To overcome these shortcomings,a kinematics analysis for a planetary gear train is firstly performed,in which the influence of relative speed is investigated.Then the finite element strength analysis of a planetary gear train based on its transient meshing properties is carried out in ANSYS.Time–history curves of contact and bending stresses of sun gear,planetary gears and ring gear are respectively obtained.Also the accurate moment and its corresponding position of the maximum stress are precisely determined.Finally,calculation results of finite element method(FEM)and traditional method are compared in order to verify the effectiveness.Simulation and comparison show the stability of the proposed method in this paper.Researches in this paper establish the foundations for fatigue analysis and optimization for a planetary gear train.
文摘Discusses the symplectic integration of separable Hamiltonian ordinary and partial differential equations (PDE). Results of a von Neumann analysis; Spectra of linearized Hamiltonian PDEs.
