A lot of study has been made for the design and defining hot end initial parameters of steem turbine of large thermal power plant at home and abroad. But little study has been performed for the reasonable selection of...A lot of study has been made for the design and defining hot end initial parameters of steem turbine of large thermal power plant at home and abroad. But little study has been performed for the reasonable selection of some cold end parameters of steam turbine. The steam turbine cold end parameters defined in actual engineering project are somewhat unreasonable frequently. This paper describes some opinions for selecting some of the steam turbine cold end parameters, especially that of the turbine design back pressure and low pressure cylinder last stage blade length based on the regional features of meteorological conditions in China in association with the optimization of thermal power plant circulating water system.展开更多
Static optimization of logical queries is, in substance, to move selections down as far as possible in evaluating logical queries. This paper extends Ullman's RGG (Rule/Goal Graph) and introduces P- graph, with wh...Static optimization of logical queries is, in substance, to move selections down as far as possible in evaluating logical queries. This paper extends Ullman's RGG (Rule/Goal Graph) and introduces P- graph, with which a wide range of recursive logical queries can be statically optimized top-down and evaluated bottom-up, some of which are usually optimized by dynamic approaches. The paper also shows that for some logical queries the complexity of pushing selections down and computing bottom-up is related to the complexity of base relation in the queries.展开更多
The effectiveness,viability and feasibility of applying Fenton reactants in treating soil contaminated with automatic gas oil(AGO)was investigated ex-situ.Soil was simulated to achieve 10%contamination using AGO(diese...The effectiveness,viability and feasibility of applying Fenton reactants in treating soil contaminated with automatic gas oil(AGO)was investigated ex-situ.Soil was simulated to achieve 10%contamination using AGO(diesel)as the primary contaminant.Physicochemical properties and heavy metal contents were characterized using standard analytical methods,while total petroleum hydrocarbon(TPH)content was determined by molecular spectroscopy.An investigation of the soil physicochemical properties shows severe impact of the contaminant on pH,conductivity,phosphorus and(TPH)content.The optimum concentration of Fenton reactants determined from the optimization study was found to be 350,000 ppm H2O2 and 600 ppm FeSO4 at optimum room temperature range of 27e30C and optimum pH of 4.7.The highly exothermic Fenton oxidation treatment resulted in significant decrease in TPH content by 87.6%after 6 h of periodic monitoring;breaking down the hydrocarbons into non-toxic environmental friendly products.Kinetics analysis and evaluation shows pseudo-first order mechanism for the Fenton treatment with a calculated rate constant of 0.226 h-1 and half life of 3 h 4 min.The Fenton method is found to be very effective and efficient not only for the removal of the diesel contaminant,but also for the restoration of lost physicochemical properties occasioned by the effect of the contaminant.The environmental friendliness and fast response time towards effective clean up gives the technique a cutting edge advantage over other conventional methods.It therefore presents potentials for remediation experts in outright applications on real field challenges.展开更多
文摘A lot of study has been made for the design and defining hot end initial parameters of steem turbine of large thermal power plant at home and abroad. But little study has been performed for the reasonable selection of some cold end parameters of steam turbine. The steam turbine cold end parameters defined in actual engineering project are somewhat unreasonable frequently. This paper describes some opinions for selecting some of the steam turbine cold end parameters, especially that of the turbine design back pressure and low pressure cylinder last stage blade length based on the regional features of meteorological conditions in China in association with the optimization of thermal power plant circulating water system.
文摘Static optimization of logical queries is, in substance, to move selections down as far as possible in evaluating logical queries. This paper extends Ullman's RGG (Rule/Goal Graph) and introduces P- graph, with which a wide range of recursive logical queries can be statically optimized top-down and evaluated bottom-up, some of which are usually optimized by dynamic approaches. The paper also shows that for some logical queries the complexity of pushing selections down and computing bottom-up is related to the complexity of base relation in the queries.
文摘The effectiveness,viability and feasibility of applying Fenton reactants in treating soil contaminated with automatic gas oil(AGO)was investigated ex-situ.Soil was simulated to achieve 10%contamination using AGO(diesel)as the primary contaminant.Physicochemical properties and heavy metal contents were characterized using standard analytical methods,while total petroleum hydrocarbon(TPH)content was determined by molecular spectroscopy.An investigation of the soil physicochemical properties shows severe impact of the contaminant on pH,conductivity,phosphorus and(TPH)content.The optimum concentration of Fenton reactants determined from the optimization study was found to be 350,000 ppm H2O2 and 600 ppm FeSO4 at optimum room temperature range of 27e30C and optimum pH of 4.7.The highly exothermic Fenton oxidation treatment resulted in significant decrease in TPH content by 87.6%after 6 h of periodic monitoring;breaking down the hydrocarbons into non-toxic environmental friendly products.Kinetics analysis and evaluation shows pseudo-first order mechanism for the Fenton treatment with a calculated rate constant of 0.226 h-1 and half life of 3 h 4 min.The Fenton method is found to be very effective and efficient not only for the removal of the diesel contaminant,but also for the restoration of lost physicochemical properties occasioned by the effect of the contaminant.The environmental friendliness and fast response time towards effective clean up gives the technique a cutting edge advantage over other conventional methods.It therefore presents potentials for remediation experts in outright applications on real field challenges.
