The lattice Boltzmann method (LBM) is employed to simulate the uniform flow past a circular cylinder. The performance of the two-dimensional LBM model on the prediction of force coefficients and vortex shedding freque...The lattice Boltzmann method (LBM) is employed to simulate the uniform flow past a circular cylinder. The performance of the two-dimensional LBM model on the prediction of force coefficients and vortex shedding frequency is investigated. The local grid refinement technique and second-order boundary condition for curved walls are applied in the calculations. It is found that the calculated vortex shedding frequency, drag coefficient and lift coefficient are consistent with experimental results at Reynolds nu...展开更多
This article has suggested that high oil price could loom many years in the future and has analyzed the impact of this trend on the oil product mix and petroleum refining industry in China. This article has also put f...This article has suggested that high oil price could loom many years in the future and has analyzed the impact of this trend on the oil product mix and petroleum refining industry in China. This article has also put forward measures for sharpening the international competitive edge of China’s petroleum refining indus- try to cope with the challenges of high oil price.展开更多
According to the Energy Information Administration, average retail gasoline prices tend to typically be higher in certain states than in others. Aside from taxes, the factors shown to contribute to regional and even l...According to the Energy Information Administration, average retail gasoline prices tend to typically be higher in certain states than in others. Aside from taxes, the factors shown to contribute to regional and even local differences in gasoline prices include proximity of supply, supply disruptions, competition in the local market and environmental programs. Of interest in this paper is proximity of supply. It has been hypothesized that areas farthest from the Gulf Coast （the source of nearly half of the gasoline produced in the United States and, thus, a major supplier to the rest of the country） tend to have higher prices. To test this hypothesis, the paper assembles state level monthly retail gasoline data for the period 1983 to 2007 for five states with oil refineries （Alabama, Georgia, Texas, Mississippi and Louisiana） and five states without refineries （Arkansas, Tennessee, North Carolina, South Carolina and Florida）. The analysis employs dynamic correlation, regression, cointegration and vector autoregressive methods. Overall, the results show that retail gas prices in states with refineries and those without refineries tend to move in the same direction over time. The small differences observed over time may suggest that price shocks take a short time to be felt nationwide.展开更多
If assortment priee parity of Clase coking coal and its qtalty price danrcnee is nonreasonable, it deren't gulde in Anprotrig tbe quallry metaliurgical coking coal and may be influence theeconomic benefit of me...If assortment priee parity of Clase coking coal and its qtalty price danrcnee is nonreasonable, it deren't gulde in Anprotrig tbe quallry metaliurgical coking coal and may be influence theeconomic benefit of metallurgical enterprises. This paper propose the principles and mathematicmodel for determination aseortment party of clean cokingcoal and its quality difference of ash content in clean coking coal in order to urge wasbenes into producing superior clean coking cleal whichis under condition of consideration both interest waskeries and interest metallurgicai industry. It canbe used as a method in theory to make price strategies under condition of socialism maket economicfor washeries of clean coking coal展开更多
基金Supported by the Specialized Research Fund for the Doctoral Program of Higher Education (No. 20060056036)
文摘The lattice Boltzmann method (LBM) is employed to simulate the uniform flow past a circular cylinder. The performance of the two-dimensional LBM model on the prediction of force coefficients and vortex shedding frequency is investigated. The local grid refinement technique and second-order boundary condition for curved walls are applied in the calculations. It is found that the calculated vortex shedding frequency, drag coefficient and lift coefficient are consistent with experimental results at Reynolds nu...
文摘This article has suggested that high oil price could loom many years in the future and has analyzed the impact of this trend on the oil product mix and petroleum refining industry in China. This article has also put forward measures for sharpening the international competitive edge of China’s petroleum refining indus- try to cope with the challenges of high oil price.
文摘According to the Energy Information Administration, average retail gasoline prices tend to typically be higher in certain states than in others. Aside from taxes, the factors shown to contribute to regional and even local differences in gasoline prices include proximity of supply, supply disruptions, competition in the local market and environmental programs. Of interest in this paper is proximity of supply. It has been hypothesized that areas farthest from the Gulf Coast （the source of nearly half of the gasoline produced in the United States and, thus, a major supplier to the rest of the country） tend to have higher prices. To test this hypothesis, the paper assembles state level monthly retail gasoline data for the period 1983 to 2007 for five states with oil refineries （Alabama, Georgia, Texas, Mississippi and Louisiana） and five states without refineries （Arkansas, Tennessee, North Carolina, South Carolina and Florida）. The analysis employs dynamic correlation, regression, cointegration and vector autoregressive methods. Overall, the results show that retail gas prices in states with refineries and those without refineries tend to move in the same direction over time. The small differences observed over time may suggest that price shocks take a short time to be felt nationwide.
文摘If assortment priee parity of Clase coking coal and its qtalty price danrcnee is nonreasonable, it deren't gulde in Anprotrig tbe quallry metaliurgical coking coal and may be influence theeconomic benefit of metallurgical enterprises. This paper propose the principles and mathematicmodel for determination aseortment party of clean cokingcoal and its quality difference of ash content in clean coking coal in order to urge wasbenes into producing superior clean coking cleal whichis under condition of consideration both interest waskeries and interest metallurgicai industry. It canbe used as a method in theory to make price strategies under condition of socialism maket economicfor washeries of clean coking coal
