two equations for the calculation of surface tension of pure liquids are derived based on statistical thermodyanics by expressing the intermolecular potential as lennard-Jones pair potential.This method is simple,accu...two equations for the calculation of surface tension of pure liquids are derived based on statistical thermodyanics by expressing the intermolecular potential as lennard-Jones pair potential.This method is simple,accurate and easy to use.The calculation results for the 22 pure liquids show that these equations are superior to the empirical forula and other theoretical equations.The average relative deviations for these two equations are within 5% and 1.5% respectively.展开更多
The wind power potential in Interior Alaska is evaluated from a micrometeorological perspective. Based on the local balance equation of momentum and the equation of continuity we derive the local balance equation of k...The wind power potential in Interior Alaska is evaluated from a micrometeorological perspective. Based on the local balance equation of momentum and the equation of continuity we derive the local balance equation of kinetic energy for macroscopic and turbulent systems, and in a further step, Bernoulli’s equation and integral equations that customarily serve as the key equations in momentum theory and blade-element analysis, where the Lanchester-Betz-Joukowsky limit, Glauert’s optimum actuator disk, and the results of the blade-element analysis by Okulov and Sorensen are exemplarily illustrated. The wind power potential at three different sites in Interior Alaska (Delta Junction, Eva Creek, and Poker Flat) is assessed by considering the results of wind field predictions for the winter period from October 1, 2008, to April 1, 2009 provided by the Weather Research and Forecasting (WRF) model to avoid time-consuming and expensive tall-tower observations in Interior Alaska which is characterized by a relatively low degree of infrastructure outside of the city of Fairbanks. To predict the average power output we use the Weibull distributions derived from the predicted wind fields for these three different sites and the power curves of five different propeller-type wind turbines with rated powers ranging from 2 MW to 2.5 MW. These power curves are represented by general logistic functions. The predicted power capacity for the Eva Creek site is compared with that of the Eva Creek wind farm established in 2012. The results of our predictions for the winter period 2008/2009 are nearly 20 percent lower than those of the Eva Creek wind farm for the period from January to September 2013.展开更多
Charging mechanism of dust particles has been considered as a growing research area in dusty plasma physics because of its exciting results.In this paper,we consider a low-temperature non-equilibrium multispecies plas...Charging mechanism of dust particles has been considered as a growing research area in dusty plasma physics because of its exciting results.In this paper,we consider a low-temperature non-equilibrium multispecies plasma model,which consists of Vasyliunas-Caims (VC) distributed electrons,negative/positive streaming ions,and negatively-charged dust grains to explain the charging mechanism of dust grains.The main theme of this work is to derive expressions of currents for negatively-charged dust grains (considering an equilibrium state position) in the plasma environment comprised of electrons and positive/negative streaming ions using the VC distribution function.Our proposed model shows that the dust grain surface potential is significantly affected by different plasma parameters such as the negative ion streaming velocity (Sn),positive ion streaming velocity (Si),spectral indices of VC distribution,negative ion charging state (Zn),positive ion charging state (Zi),and negative ion number density (ρ).展开更多
文摘two equations for the calculation of surface tension of pure liquids are derived based on statistical thermodyanics by expressing the intermolecular potential as lennard-Jones pair potential.This method is simple,accurate and easy to use.The calculation results for the 22 pure liquids show that these equations are superior to the empirical forula and other theoretical equations.The average relative deviations for these two equations are within 5% and 1.5% respectively.
基金the National Science Foundation for funding the project work of Megan Hinzman and Samuel Smock in summer 2011Hannah K.Ross and John Cooney in summer 2012 through the Research Experience for Undergraduates(REU)Program,grant number AGS1005265the Alaska Department of Labor for funding Dr.Gary Sellhorst’s project work
文摘The wind power potential in Interior Alaska is evaluated from a micrometeorological perspective. Based on the local balance equation of momentum and the equation of continuity we derive the local balance equation of kinetic energy for macroscopic and turbulent systems, and in a further step, Bernoulli’s equation and integral equations that customarily serve as the key equations in momentum theory and blade-element analysis, where the Lanchester-Betz-Joukowsky limit, Glauert’s optimum actuator disk, and the results of the blade-element analysis by Okulov and Sorensen are exemplarily illustrated. The wind power potential at three different sites in Interior Alaska (Delta Junction, Eva Creek, and Poker Flat) is assessed by considering the results of wind field predictions for the winter period from October 1, 2008, to April 1, 2009 provided by the Weather Research and Forecasting (WRF) model to avoid time-consuming and expensive tall-tower observations in Interior Alaska which is characterized by a relatively low degree of infrastructure outside of the city of Fairbanks. To predict the average power output we use the Weibull distributions derived from the predicted wind fields for these three different sites and the power curves of five different propeller-type wind turbines with rated powers ranging from 2 MW to 2.5 MW. These power curves are represented by general logistic functions. The predicted power capacity for the Eva Creek site is compared with that of the Eva Creek wind farm established in 2012. The results of our predictions for the winter period 2008/2009 are nearly 20 percent lower than those of the Eva Creek wind farm for the period from January to September 2013.
文摘Charging mechanism of dust particles has been considered as a growing research area in dusty plasma physics because of its exciting results.In this paper,we consider a low-temperature non-equilibrium multispecies plasma model,which consists of Vasyliunas-Caims (VC) distributed electrons,negative/positive streaming ions,and negatively-charged dust grains to explain the charging mechanism of dust grains.The main theme of this work is to derive expressions of currents for negatively-charged dust grains (considering an equilibrium state position) in the plasma environment comprised of electrons and positive/negative streaming ions using the VC distribution function.Our proposed model shows that the dust grain surface potential is significantly affected by different plasma parameters such as the negative ion streaming velocity (Sn),positive ion streaming velocity (Si),spectral indices of VC distribution,negative ion charging state (Zn),positive ion charging state (Zi),and negative ion number density (ρ).
