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
Solid oxide fuel cells(SOFCs)are an advanced green energy technology that efficiently harnesses H2 and is very important in transforming the energy landscape of vehicles.However,traditional SOFCs often struggle to mee...Solid oxide fuel cells(SOFCs)are an advanced green energy technology that efficiently harnesses H2 and is very important in transforming the energy landscape of vehicles.However,traditional SOFCs often struggle to meet vehicle performance demands.For anode-supported automotive SOFCs,the gradient anode design is considered an important structure that is expected to enhance the comprehensive performance.Although the optimization of anodes with gradient porosity and particle size has been well studied,the optimization of anodes with gradient component distributions has not been adequately researched.The performance of SOFC with homogenous anode components is well researched.The study analyzed the effect of the number of anode functional layers(AFLs)on SOFC performance,and the component distribution of the layered AFL was optimized using a combination of a back-propagation neural network(BPNN)and a genetic algorithm(GA).Finally,the distribution of the continuous gradient components in the AFL was optimized using the same methodology.The results show that the variation of component distribution in the anode support layer(ASL)has minimal impact on the SOFC performance;however,the SOFC performance is significantly enhanced when the anode is structured with two layers(l=2).The maximum power density(Pmax)of the layered anode(l=2)with optimized gradient components increased by 10.63%compared to a homogeneous anode structure.This improvement is observed when the electron conductor volume fractions of AFL1 and AFL2 are set at 64.37%and 46.50%,respectively,and when the components of AFL are continuously distributed according to a power function,the Pmax surpasses all other tested conditions.展开更多
In order to ensure the production quality and sustainable development of water supply enterprises, optimizing the production cost control of water supply enterprises is an important subject to be studied urgently. Com...In order to ensure the production quality and sustainable development of water supply enterprises, optimizing the production cost control of water supply enterprises is an important subject to be studied urgently. Combined with the characteristics of water supply enterprises, from the perspective of production cost management, this paper studies how to strengthen the cost control of water supply enterprises in daily management, improve the production quality, operating benefits and social benefits of water supply enterprises, and promote the long-term steady development of water supply companies.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.
基金funded by National Natural Science Foundation of China(52306068,52302427)Natural Science Basis Research Plan in Shaanxi Province of China(2023-JC-QN-0464)as well as Fundamental Research Funds for the Central Universities,CHD(300102224203,300102224201).
文摘Solid oxide fuel cells(SOFCs)are an advanced green energy technology that efficiently harnesses H2 and is very important in transforming the energy landscape of vehicles.However,traditional SOFCs often struggle to meet vehicle performance demands.For anode-supported automotive SOFCs,the gradient anode design is considered an important structure that is expected to enhance the comprehensive performance.Although the optimization of anodes with gradient porosity and particle size has been well studied,the optimization of anodes with gradient component distributions has not been adequately researched.The performance of SOFC with homogenous anode components is well researched.The study analyzed the effect of the number of anode functional layers(AFLs)on SOFC performance,and the component distribution of the layered AFL was optimized using a combination of a back-propagation neural network(BPNN)and a genetic algorithm(GA).Finally,the distribution of the continuous gradient components in the AFL was optimized using the same methodology.The results show that the variation of component distribution in the anode support layer(ASL)has minimal impact on the SOFC performance;however,the SOFC performance is significantly enhanced when the anode is structured with two layers(l=2).The maximum power density(Pmax)of the layered anode(l=2)with optimized gradient components increased by 10.63%compared to a homogeneous anode structure.This improvement is observed when the electron conductor volume fractions of AFL1 and AFL2 are set at 64.37%and 46.50%,respectively,and when the components of AFL are continuously distributed according to a power function,the Pmax surpasses all other tested conditions.
文摘In order to ensure the production quality and sustainable development of water supply enterprises, optimizing the production cost control of water supply enterprises is an important subject to be studied urgently. Combined with the characteristics of water supply enterprises, from the perspective of production cost management, this paper studies how to strengthen the cost control of water supply enterprises in daily management, improve the production quality, operating benefits and social benefits of water supply enterprises, and promote the long-term steady development of water supply companies.
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.
