This paper addresses the lane-keeping control problem for autonomous ground vehicles subject to input saturation and uncertain system parameters.An enhanced adaptive terminal sliding mode based prescribed performance ...This paper addresses the lane-keeping control problem for autonomous ground vehicles subject to input saturation and uncertain system parameters.An enhanced adaptive terminal sliding mode based prescribed performance control scheme is proposed,which enables the lateral position error of the vehicle to be kept within the prescribed performance boundaries all the time.This is achieved by firstly introducing an improved performance function into the controller design such that the stringent initial condition requirements can be relaxed,which further allows the global prescribed performance control result,and then,developing a multivariable adaptive terminal sliding mode based controller such that both input saturation and parameter uncertainties are handled effectively,which further ensures the robust lane-keeping control.Finally,the proposed control strategy is validated through numerical simulations,demonstrating its effectiveness.展开更多
The mixing injection of natural gas and pulverized coal into the blast furnaces shows a promising technological approach in the context of global carbon reduction initiatives.Carrier gas and coal pass through the air ...The mixing injection of natural gas and pulverized coal into the blast furnaces shows a promising technological approach in the context of global carbon reduction initiatives.Carrier gas and coal pass through the air inlet of coal lance,and the characteristics of carrier gas affect the flow in the air inlet and the combustion efficiency of coal,so it is very important to study the change of carrier gas charac-teristics in the lower part of blast furnace.By means of numerical simulation,the influence of carrier gas characteristics(injection rate,composition,and temperature)on the mixed combustion of natural gas(NG)and pulverized coal in the tuyere raceway of Russian blast furnace was analyzed.When N_(2) is used as carrier gas,the injection rate of carrier gas is reduced from 4000 to 2000 m3/h,the average tuy-ere temperature is increased(1947.42 to 1963.30 K),the mole fractions of CO and H_(2) are increased,and the burnout rate of pulverized coal is decreased.Increasing the carrier gas temperature is helpful to improve the burnout of pulverized coal.For every 20 K increase of carrier gas temperature,the average temperature in the raceway increases by 20.6 K,which promotes the release and combustion of volat-iles,but the increase of carrier gas temperature from 373 to 393 K only leads to 1.16%burnout change.Considering the transportation characteristics of pulverized coal,it is suggested that the carrier gas temperature should be kept at about 373 K to obtain the best perform-ance.It is worth noting that when air is used as carrier gas,the burnout rate of pulverized coal is increased by 2.69%compared with N_(2).展开更多
The influence of Al content(0.0053,0.0171,and 0.0578 wt.%)on the modification behavior of non-metallic inclusions in 20CrMoVTiB steel treated with rare earth elements was studied through high-temperature experiments a...The influence of Al content(0.0053,0.0171,and 0.0578 wt.%)on the modification behavior of non-metallic inclusions in 20CrMoVTiB steel treated with rare earth elements was studied through high-temperature experiments and thermodynamic simulation.The results showed that the modification products varied with the Al content in steel under 0.01 wt.%of Ce addition.The formation sequence of typical rare earth inclusions in steel with the increase in Al content was Ce_(2)O_(3)→CeAlO_(3)→CeAl_(11)O_(18),and the final stable products were highly Al content dependent.When the Al content was 0.0053 wt.%,the stable phase in steel was Ce2O3;while the[Al]reached 0.0171 wt.%,the stable phase became CeA1O_(3).As the A1 content reached 0.0578 wt.%,CeAl_(11)O_(18) became the stable phase.As a result,increasing the Al content could inhibit the precipitation of Ce_(2)O_(3) inclusions in steel while promote the formation of CeAIO3 and CeAl_(11)O_(18) inclusions.In addition,both Ca treatment and Ce treatment could effectively refine the size of inclusions in steel by changing their types.However,the feeding amount of Ca wire into molten steel should be appropriately reduced under the condition of adding Ce simultaneously,which is expected to be beneficial for an improved Ce treatment effect.展开更多
The sticking phenomenon between molten slag and refractory is one of the crucial problems when preparing ferronickel from laterite ore using rotary hearth fulnace or rotary kiln processes. This study aims to ameliorat...The sticking phenomenon between molten slag and refractory is one of the crucial problems when preparing ferronickel from laterite ore using rotary hearth fulnace or rotary kiln processes. This study aims to ameliorate sticking problems by using silicon dioxide （SiO2） to adjust the melting degree of file briquette during reduction roasting. Thermodynamic analysis indicates that the melting temperature of the slag gradually increases with an increase in the SiO2 proportion （SiO2/（SiO2 ＋ A1203 ＋ MgO） mass ratio）. Experimental validations also prove that the briquette retains its original shape when the SiO2 proportion is greater than 75wt%, and sticking problems axe avoided during reduction. A ferronickel product with 8.33wt% Ni and 84.71wt% Fe was prepared via reductive roasting at 1500~C for 90 min with a SiO2 proportion of 75wt% and a C/O molar ratio of 1.0 followed by dry magnetic separation; the corresponding recoveries of Ni and Fe reached 75.70% and 77.97%, respectively. The micro stxucture and phase txmlsformation of reduced briquette reveals that the aggregation and growth of ferroinckel particles were not significantly affected after adding SiO2 to the reduction process.展开更多
This study discusses the key factors limiting the rate of pulverized coal injection （PCI） in blast furnaces （BF）, while the practice and experiences of Baosteel＇ s BF production with high productivity and low fue...This study discusses the key factors limiting the rate of pulverized coal injection （PCI） in blast furnaces （BF）, while the practice and experiences of Baosteel＇ s BF production with high productivity and low fuel consumption are also analyzed. A methodology based on technological analysis for achieving a reasonable PCI rate is proposed. It is emphasized that high BF productivity should be realized at the maximum bosh gas index based on a higher blast temperature and the excellent quality of raw materials,as well as a high blast volume and melting strength.展开更多
With the progress of science and technology and the acceleration of industrialization,the modern industrial park is an important carrier of industrial development.The importance of its standard plant design has become...With the progress of science and technology and the acceleration of industrialization,the modern industrial park is an important carrier of industrial development.The importance of its standard plant design has become increasingly prominent.With the development of new quality productive forces as the background,this research deeply discusses the key points of standard plant design in modern industrial parks.This paper uses literature review and case analysis to systematically analyze the important role of standard plant design in developing new quality productive forces in modern industrial parks and puts forward suggestions for optimizing design.It is found that the rationality,intelligence,and environmental protection of plant design are the key factors affecting the development of new quality productive forces.The paper summarizes the core points of modern industrial park standard plant design to provide a reference for the future development of related industries.展开更多
Repeatedly unidirectional bending(RUB) was applied to the magnesium alloy sheet to improve the basal texture.The effect of RUB temperature on resulting structure and room temperature properties was investigated.The te...Repeatedly unidirectional bending(RUB) was applied to the magnesium alloy sheet to improve the basal texture.The effect of RUB temperature on resulting structure and room temperature properties was investigated.The texture components of the sheet undergoing RUB at recovery temperature were similar to those of the sheet undergoing RUB at room temperature(RT).As the RUB temperature increased to above recrystallization temperature,the texture components became more disperse and the pyramidal components increased.With the increase of RUB temperature,the grain size near the surface of the sheets undergoing RUB tended to grow up.When the sheets were processed by RUB at medium-high temperature followed by annealing at 533 K,the yield strength and fracture elongation were lower than those of the cold rolled sheet;however,the Erichsen value was slightly higher than that of the cold rolled sheet.The sheet undergoing RUB at RT followed by annealing at 533 K represented the best mechanical properties.展开更多
In this paper, repeated unidirectional bending （RUB）, was applied to improve the texture of AZ31B magnesium alloy sheets so as to enhance their stamping properties. The samples undergoing RUB were annealed at differ...In this paper, repeated unidirectional bending （RUB）, was applied to improve the texture of AZ31B magnesium alloy sheets so as to enhance their stamping properties. The samples undergoing RUB were annealed at different temperatures. The mechanical properties, formability, textural components and microstructure of the samples before and after RUB were characterized and compared. It was found that the basal textural component was reduced dramatically by RUB, and that （1212） and （1211） textural components appeared. Annealing has a great effect on the mechanical properties of samples undergoing RUB. The plasticity and stamping formability of samples were greatly improved by RUB and annealing at 260℃ for 1 h, and elongation to fracture and Erichsen value were increased to 38% and 67%, respectively.展开更多
According to the two types of slab defects （surface crack and internal crack）, a real-time slab quality diag nosis and analysis system named CISDI_SQDS ONLINE R2011 was developed based on heat transfer and solidific...According to the two types of slab defects （surface crack and internal crack）, a real-time slab quality diag nosis and analysis system named CISDI_SQDS ONLINE R2011 was developed based on heat transfer and solidifica tion simulation, stress and strain calculation as well as metallurgical process analysis about continuous casting, com- bined with expert knowledge database for specific casting events. The respective crack formation indexes were intro duced as the theoretical reference data for slab quality level evaluation. Meanwhile, both the quality loss factors relat ed to casting metallurgical rules and the adjusting factors related to casting events were taken into full consideration, which was integrated organically with theoretical analysis and expert system. The system can be widely used as an important theoretical tool for prediction and control of slab quality in slab continuous casting process.展开更多
An algorithm for the inverse of a general tridiagonal matrix is presented. For a tridiagonal matrix having the Doolittle factorization, an inversion algorithm is established. The algorithm is then generalized to deal ...An algorithm for the inverse of a general tridiagonal matrix is presented. For a tridiagonal matrix having the Doolittle factorization, an inversion algorithm is established. The algorithm is then generalized to deal with a general tridiagonal matrix without any restriction. Comparison with other methods is provided, indicating low computational complexity of the proposed algorithm, and its applicability to general tridiagonal matrices.展开更多
Al_(2)O_(3)-SiO_(2) based gunning mixes were prepared with electric porcelain waste,silica fume,bauxite,quartz powder,and calcium aluminate cement(CAC)of different additions as raw materials firing at different temper...Al_(2)O_(3)-SiO_(2) based gunning mixes were prepared with electric porcelain waste,silica fume,bauxite,quartz powder,and calcium aluminate cement(CAC)of different additions as raw materials firing at different temperatures to research the effect of the CAC addition on their phase change and properties.The results show that:from theoretical analysis of the phase diagram,with the CAC addition increasing from 8%to 14%,anorthite increases from 40.0%to 77.7%,by mass.With the rising CAC addition,the permanent linear change on heating of specimens increases;for the specimens dried at 110℃or hot-treated at 1000℃,the bulk density and the mechanical properties increase,and the apparent porosity decreases;and for those hottreated at 1300℃,the bulk density and the mechanical properties firstly increase,and then decrease,while the apparent porosity shows an opposite trend.Taking into account the phases at high temperatures and the properties,the optimal CAC addition of Al_(2)O_(3)-SiO_(2) based gunning mixes is 12%.展开更多
The high chrome refractories were crushed,ground into powder and sampled.A mixture solution of sodium carbonate and sodium hydroxide was used to extract the powder samples.The extracted solution from the samples was m...The high chrome refractories were crushed,ground into powder and sampled.A mixture solution of sodium carbonate and sodium hydroxide was used to extract the powder samples.The extracted solution from the samples was mixed and reacted with diphenylcarbazide to form colored substance.The hexavalent chromium content in the samples was determined by spectrophotometry.The effects of the extracting conditions,the color reagent reaction conditions,the sample mass,the working curve and the trivalent chromium coexistence on the results were studied.The experiments about determination,recovery and precision were carried out.The relative standard deviation was less than 5%and the recovery rate was 98%-104%.展开更多
In order to make further study on the mechanical property of CRTSIII type slab non-ballast track structures,which was self-designed in China,based on the method of the multiscale finite element model(FEM),the traditio...In order to make further study on the mechanical property of CRTSIII type slab non-ballast track structures,which was self-designed in China,based on the method of the multiscale finite element model(FEM),the traditional FEM of slab non-ballast track structures was improved.The multiscale FEM of CRTSII type slab nonballast track structures was established based on the general finite element program ABAQUs.Then the comparative calculation was made between various FEMs,showing that the high solution precision,fast modelling speed and high solution efficiency could be obtained.Therefore,the multiscale FEM was suitable for the parametric study on mechanical behaviour of CRTSII type slab non-ballast track structures,and then the key influence factor and constructions could be optimized.展开更多
基金supported in part by the National Key Research and Development Program of China under Grant 2023YFA1011803in part by Natural Science Foundation of Chongqing,China under Grant CSTB2023NSCQ-MSX0588+2 种基金in part by the Fundamental Research Funds for the Central Universities,China under Grant 2023CDJKYJH047in part by the National Natural Science Foundation of China under Grant 62273064,Grant 61991400,Grant 61991403,Grant 61933012,Grant 62250710167,Grant 62203078in part by Innovation Support Program for International Students Returning to China under Grant cx2022016.
文摘This paper addresses the lane-keeping control problem for autonomous ground vehicles subject to input saturation and uncertain system parameters.An enhanced adaptive terminal sliding mode based prescribed performance control scheme is proposed,which enables the lateral position error of the vehicle to be kept within the prescribed performance boundaries all the time.This is achieved by firstly introducing an improved performance function into the controller design such that the stringent initial condition requirements can be relaxed,which further allows the global prescribed performance control result,and then,developing a multivariable adaptive terminal sliding mode based controller such that both input saturation and parameter uncertainties are handled effectively,which further ensures the robust lane-keeping control.Finally,the proposed control strategy is validated through numerical simulations,demonstrating its effectiveness.
基金financially supported by the National Key R&D Program of China(No.2022YFE0208100)the Major Science and Technology Project of Xinjiang Uygur Autonomous Region,China(No.2022A01003)+1 种基金the Key Research and Development Plan of Anhui Province,China(No.202210700037)the National Natural Science Foundation of China(No.52274316).
文摘The mixing injection of natural gas and pulverized coal into the blast furnaces shows a promising technological approach in the context of global carbon reduction initiatives.Carrier gas and coal pass through the air inlet of coal lance,and the characteristics of carrier gas affect the flow in the air inlet and the combustion efficiency of coal,so it is very important to study the change of carrier gas charac-teristics in the lower part of blast furnace.By means of numerical simulation,the influence of carrier gas characteristics(injection rate,composition,and temperature)on the mixed combustion of natural gas(NG)and pulverized coal in the tuyere raceway of Russian blast furnace was analyzed.When N_(2) is used as carrier gas,the injection rate of carrier gas is reduced from 4000 to 2000 m3/h,the average tuy-ere temperature is increased(1947.42 to 1963.30 K),the mole fractions of CO and H_(2) are increased,and the burnout rate of pulverized coal is decreased.Increasing the carrier gas temperature is helpful to improve the burnout of pulverized coal.For every 20 K increase of carrier gas temperature,the average temperature in the raceway increases by 20.6 K,which promotes the release and combustion of volat-iles,but the increase of carrier gas temperature from 373 to 393 K only leads to 1.16%burnout change.Considering the transportation characteristics of pulverized coal,it is suggested that the carrier gas temperature should be kept at about 373 K to obtain the best perform-ance.It is worth noting that when air is used as carrier gas,the burnout rate of pulverized coal is increased by 2.69%compared with N_(2).
基金This research was funded by National Natural Science Foundation of China(Grant No.51874033)Beijing Natural Science Foundation(Grant No.2182038)to Hai-yan Tang.
文摘The influence of Al content(0.0053,0.0171,and 0.0578 wt.%)on the modification behavior of non-metallic inclusions in 20CrMoVTiB steel treated with rare earth elements was studied through high-temperature experiments and thermodynamic simulation.The results showed that the modification products varied with the Al content in steel under 0.01 wt.%of Ce addition.The formation sequence of typical rare earth inclusions in steel with the increase in Al content was Ce_(2)O_(3)→CeAlO_(3)→CeAl_(11)O_(18),and the final stable products were highly Al content dependent.When the Al content was 0.0053 wt.%,the stable phase in steel was Ce2O3;while the[Al]reached 0.0171 wt.%,the stable phase became CeA1O_(3).As the A1 content reached 0.0578 wt.%,CeAl_(11)O_(18) became the stable phase.As a result,increasing the Al content could inhibit the precipitation of Ce_(2)O_(3) inclusions in steel while promote the formation of CeAIO3 and CeAl_(11)O_(18) inclusions.In addition,both Ca treatment and Ce treatment could effectively refine the size of inclusions in steel by changing their types.However,the feeding amount of Ca wire into molten steel should be appropriately reduced under the condition of adding Ce simultaneously,which is expected to be beneficial for an improved Ce treatment effect.
基金the National Natural Science Foundation of China(No.51234010)the Fundamental Research Funds for Central Universities(No.106112017CDJXY130001)for the financial support provided for this research
文摘The sticking phenomenon between molten slag and refractory is one of the crucial problems when preparing ferronickel from laterite ore using rotary hearth fulnace or rotary kiln processes. This study aims to ameliorate sticking problems by using silicon dioxide （SiO2） to adjust the melting degree of file briquette during reduction roasting. Thermodynamic analysis indicates that the melting temperature of the slag gradually increases with an increase in the SiO2 proportion （SiO2/（SiO2 ＋ A1203 ＋ MgO） mass ratio）. Experimental validations also prove that the briquette retains its original shape when the SiO2 proportion is greater than 75wt%, and sticking problems axe avoided during reduction. A ferronickel product with 8.33wt% Ni and 84.71wt% Fe was prepared via reductive roasting at 1500~C for 90 min with a SiO2 proportion of 75wt% and a C/O molar ratio of 1.0 followed by dry magnetic separation; the corresponding recoveries of Ni and Fe reached 75.70% and 77.97%, respectively. The micro stxucture and phase txmlsformation of reduced briquette reveals that the aggregation and growth of ferroinckel particles were not significantly affected after adding SiO2 to the reduction process.
文摘This study discusses the key factors limiting the rate of pulverized coal injection （PCI） in blast furnaces （BF）, while the practice and experiences of Baosteel＇ s BF production with high productivity and low fuel consumption are also analyzed. A methodology based on technological analysis for achieving a reasonable PCI rate is proposed. It is emphasized that high BF productivity should be realized at the maximum bosh gas index based on a higher blast temperature and the excellent quality of raw materials,as well as a high blast volume and melting strength.
文摘With the progress of science and technology and the acceleration of industrialization,the modern industrial park is an important carrier of industrial development.The importance of its standard plant design has become increasingly prominent.With the development of new quality productive forces as the background,this research deeply discusses the key points of standard plant design in modern industrial parks.This paper uses literature review and case analysis to systematically analyze the important role of standard plant design in developing new quality productive forces in modern industrial parks and puts forward suggestions for optimizing design.It is found that the rationality,intelligence,and environmental protection of plant design are the key factors affecting the development of new quality productive forces.The paper summarizes the core points of modern industrial park standard plant design to provide a reference for the future development of related industries.
基金Project(50504019) supported by the National Natural Science Foundation of ChinaProject(2008BB4040) supported by the Science Foundation of Chongqing, ChinaProject(2008AA4028) supported by Scientific and Technological Project of Chongqing Science and Technology Commission, China
文摘Repeatedly unidirectional bending(RUB) was applied to the magnesium alloy sheet to improve the basal texture.The effect of RUB temperature on resulting structure and room temperature properties was investigated.The texture components of the sheet undergoing RUB at recovery temperature were similar to those of the sheet undergoing RUB at room temperature(RT).As the RUB temperature increased to above recrystallization temperature,the texture components became more disperse and the pyramidal components increased.With the increase of RUB temperature,the grain size near the surface of the sheets undergoing RUB tended to grow up.When the sheets were processed by RUB at medium-high temperature followed by annealing at 533 K,the yield strength and fracture elongation were lower than those of the cold rolled sheet;however,the Erichsen value was slightly higher than that of the cold rolled sheet.The sheet undergoing RUB at RT followed by annealing at 533 K represented the best mechanical properties.
基金supported by the National Natural Science Foundation of China under Grant No. 50504019Natural Science Foundation Project of CQ CSTC under Grant No. 2008BB4040
文摘In this paper, repeated unidirectional bending （RUB）, was applied to improve the texture of AZ31B magnesium alloy sheets so as to enhance their stamping properties. The samples undergoing RUB were annealed at different temperatures. The mechanical properties, formability, textural components and microstructure of the samples before and after RUB were characterized and compared. It was found that the basal textural component was reduced dramatically by RUB, and that （1212） and （1211） textural components appeared. Annealing has a great effect on the mechanical properties of samples undergoing RUB. The plasticity and stamping formability of samples were greatly improved by RUB and annealing at 260℃ for 1 h, and elongation to fracture and Erichsen value were increased to 38% and 67%, respectively.
文摘According to the two types of slab defects （surface crack and internal crack）, a real-time slab quality diag nosis and analysis system named CISDI_SQDS ONLINE R2011 was developed based on heat transfer and solidifica tion simulation, stress and strain calculation as well as metallurgical process analysis about continuous casting, com- bined with expert knowledge database for specific casting events. The respective crack formation indexes were intro duced as the theoretical reference data for slab quality level evaluation. Meanwhile, both the quality loss factors relat ed to casting metallurgical rules and the adjusting factors related to casting events were taken into full consideration, which was integrated organically with theoretical analysis and expert system. The system can be widely used as an important theoretical tool for prediction and control of slab quality in slab continuous casting process.
基金supported by the National Natural Science Foundation of China (No. 10771030)the Key Project of Ministry of Education of China (No. 107098)+1 种基金the Specialized Research Fund for the Doc-toral Program of Higher Education of China (No. 20070614001)the Applied Basic ResearchProject of Sichuan Province (No. 2008JY0052)
文摘An algorithm for the inverse of a general tridiagonal matrix is presented. For a tridiagonal matrix having the Doolittle factorization, an inversion algorithm is established. The algorithm is then generalized to deal with a general tridiagonal matrix without any restriction. Comparison with other methods is provided, indicating low computational complexity of the proposed algorithm, and its applicability to general tridiagonal matrices.
文摘Al_(2)O_(3)-SiO_(2) based gunning mixes were prepared with electric porcelain waste,silica fume,bauxite,quartz powder,and calcium aluminate cement(CAC)of different additions as raw materials firing at different temperatures to research the effect of the CAC addition on their phase change and properties.The results show that:from theoretical analysis of the phase diagram,with the CAC addition increasing from 8%to 14%,anorthite increases from 40.0%to 77.7%,by mass.With the rising CAC addition,the permanent linear change on heating of specimens increases;for the specimens dried at 110℃or hot-treated at 1000℃,the bulk density and the mechanical properties increase,and the apparent porosity decreases;and for those hottreated at 1300℃,the bulk density and the mechanical properties firstly increase,and then decrease,while the apparent porosity shows an opposite trend.Taking into account the phases at high temperatures and the properties,the optimal CAC addition of Al_(2)O_(3)-SiO_(2) based gunning mixes is 12%.
文摘The high chrome refractories were crushed,ground into powder and sampled.A mixture solution of sodium carbonate and sodium hydroxide was used to extract the powder samples.The extracted solution from the samples was mixed and reacted with diphenylcarbazide to form colored substance.The hexavalent chromium content in the samples was determined by spectrophotometry.The effects of the extracting conditions,the color reagent reaction conditions,the sample mass,the working curve and the trivalent chromium coexistence on the results were studied.The experiments about determination,recovery and precision were carried out.The relative standard deviation was less than 5%and the recovery rate was 98%-104%.
基金supported by“111”Project(B18062)Fundamental Research Funds for the Central Universities(2019CDQYTM028).
文摘In order to make further study on the mechanical property of CRTSIII type slab non-ballast track structures,which was self-designed in China,based on the method of the multiscale finite element model(FEM),the traditional FEM of slab non-ballast track structures was improved.The multiscale FEM of CRTSII type slab nonballast track structures was established based on the general finite element program ABAQUs.Then the comparative calculation was made between various FEMs,showing that the high solution precision,fast modelling speed and high solution efficiency could be obtained.Therefore,the multiscale FEM was suitable for the parametric study on mechanical behaviour of CRTSII type slab non-ballast track structures,and then the key influence factor and constructions could be optimized.
