Search1998 Vol. 5, No. 2
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1998, vol. 5, no. 2, pp.
57-60.
Abstract:
A method to determine optimum production is presented. First, based on analysis of various geological, technological and economic factors that influence the determination of underground mine capacity, a feasible range of production capacity is selected. Second, by means of scale economic theory and depletion feature of mineral resounce, an economicmathematical model that aimed at maximum net profit in the whole life of mine is developed to optimum production. The model was tested in a undergrond mine.
A method to determine optimum production is presented. First, based on analysis of various geological, technological and economic factors that influence the determination of underground mine capacity, a feasible range of production capacity is selected. Second, by means of scale economic theory and depletion feature of mineral resounce, an economicmathematical model that aimed at maximum net profit in the whole life of mine is developed to optimum production. The model was tested in a undergrond mine.
1998, vol. 5, no. 2, pp.
61-64.
Abstract:
Investigation on the coal-oxygen scrap melting process shows that using internal-combustion coal-oxygen burner to melt scrap is feasible. Among four types of coal-oxygen furnaces-oxygen burner melting furnace is better than other types on the quotas of process. The metal yield is 95%~97%, the melt down carbon and sulphur contents are >1.0% and <0.080% respectively for this melting furnace. The coal-oxygen scrap melting process would have a significant effect on the technological transformation of EAF and BOF in China.
Investigation on the coal-oxygen scrap melting process shows that using internal-combustion coal-oxygen burner to melt scrap is feasible. Among four types of coal-oxygen furnaces-oxygen burner melting furnace is better than other types on the quotas of process. The metal yield is 95%~97%, the melt down carbon and sulphur contents are >1.0% and <0.080% respectively for this melting furnace. The coal-oxygen scrap melting process would have a significant effect on the technological transformation of EAF and BOF in China.
1998, vol. 5, no. 2, pp.
65-69.
Abstract:
The formation characteristics of NOx during combustion of four typical Chinese coals have been studied in a packed bed combustor. The studies included the effects of chemical composition of coals and volatile matters, and combustion conditions, i.e. preheating temperatures of combustion gas, on conversion of NOx during combustion. In term of the combustion experiments, there is a close relation between coal composition and conversions of NOx. Coals with a higher nitrogen content give a lower FNOx0, and coals with a higher volatile content give a lower FNOx0. The further devolatilization experiments showed that volatile matters in the coal have an important effect on reducing conversion of coal-nitrogen to NOx. It was interpreted as that the release of volatile matters during combustion caused a fuel-rich circumstance in the vicinity of coal particles which may restrain the formation of NOx. Preheating temperatures of combustion gas has significant effects on conversions of NOx and there exist a critical preheating temperature. At such temperature, lower FNOx0 can be reached.
The formation characteristics of NOx during combustion of four typical Chinese coals have been studied in a packed bed combustor. The studies included the effects of chemical composition of coals and volatile matters, and combustion conditions, i.e. preheating temperatures of combustion gas, on conversion of NOx during combustion. In term of the combustion experiments, there is a close relation between coal composition and conversions of NOx. Coals with a higher nitrogen content give a lower FNOx0, and coals with a higher volatile content give a lower FNOx0. The further devolatilization experiments showed that volatile matters in the coal have an important effect on reducing conversion of coal-nitrogen to NOx. It was interpreted as that the release of volatile matters during combustion caused a fuel-rich circumstance in the vicinity of coal particles which may restrain the formation of NOx. Preheating temperatures of combustion gas has significant effects on conversions of NOx and there exist a critical preheating temperature. At such temperature, lower FNOx0 can be reached.
1998, vol. 5, no. 2, pp.
69-69.
Abstract:
A new concentration transducer for the measurement of gas/solid two-phase flow in the profile of pipeline was studied. The design of grid electrode was employed, and hence the distribute of electric field in the space was homogeneous effectively. The variance of measurement value for the influence of flow regime variations has greatly reduced, and the precision of measurement was improved. Meanwhile, optimization of axial property in the grid electrode increases the ability of tracing and measuring of the concentration signal in real-time.
A new concentration transducer for the measurement of gas/solid two-phase flow in the profile of pipeline was studied. The design of grid electrode was employed, and hence the distribute of electric field in the space was homogeneous effectively. The variance of measurement value for the influence of flow regime variations has greatly reduced, and the precision of measurement was improved. Meanwhile, optimization of axial property in the grid electrode increases the ability of tracing and measuring of the concentration signal in real-time.
1998, vol. 5, no. 2, pp.
69-69.
Abstract:
With the aid of XRD, SEM and EDS etc., there is absorbed film on sand grain surface, high temperature modify makes the film sintered firmly on sand grain surface. Thus it changes physical and chemical characteristics of the film and sand grain surface, improves the wetting properties greatly, makes the fracture features of bonding bridge change from the adhesive to the cohesive and raises the strength of sodium silicate-bonded sand.
With the aid of XRD, SEM and EDS etc., there is absorbed film on sand grain surface, high temperature modify makes the film sintered firmly on sand grain surface. Thus it changes physical and chemical characteristics of the film and sand grain surface, improves the wetting properties greatly, makes the fracture features of bonding bridge change from the adhesive to the cohesive and raises the strength of sodium silicate-bonded sand.
1998, vol. 5, no. 2, pp.
70-74.
Abstract:
The effects of various combustion conditions (i.e. particle size of coals, oxygen concentration in combustion gas and coal content in the fuel bed, etc.), on reducing conversion of NOx during coal combustion were studied. Under the present combustion conditions, coals with smaller particle size gave the lower conversion of NOx, and as expected that an decrease in overall stoichiometric ratio, whether by an decrease in O2 content in combustion gas or by an increase in coal content in fuel bed would lead to a lower conversion of NOx. In order to investigate the effect of metallic oxide layers on restraining NOx formation, the combustion experiments for coal granules with adhering layer of various metallic oxides including Fe2O3, Ni2O3 and mixed oxides Fe-Ni-Ox were conducted in a packed bed combustor. The combustion experiments have shown that most of adhering materials gave considerable effect on reduction of NOx emission during coal combustion.
The effects of various combustion conditions (i.e. particle size of coals, oxygen concentration in combustion gas and coal content in the fuel bed, etc.), on reducing conversion of NOx during coal combustion were studied. Under the present combustion conditions, coals with smaller particle size gave the lower conversion of NOx, and as expected that an decrease in overall stoichiometric ratio, whether by an decrease in O2 content in combustion gas or by an increase in coal content in fuel bed would lead to a lower conversion of NOx. In order to investigate the effect of metallic oxide layers on restraining NOx formation, the combustion experiments for coal granules with adhering layer of various metallic oxides including Fe2O3, Ni2O3 and mixed oxides Fe-Ni-Ox were conducted in a packed bed combustor. The combustion experiments have shown that most of adhering materials gave considerable effect on reduction of NOx emission during coal combustion.
1998, vol. 5, no. 2, pp.
75-79.
Abstract:
A mathematical model of kinetics of carbide layer formed on the surface of steel in fused system was set up with the theory of non-stable diffusion mass transfer and regular solution sub-lattice. This model was analyzed and testified by the experiments in which the VC layers were formed on four kinds of steels as steel 45,4Cr5MoSiV1,T10, and Cr12MoV immersed in the V2O5-Na2O-B2O5 fused system with the reducing agent of silicon.The results showed that there was a good agreement between the model and the experimental results;the growth speed of carbide layer depended on the factors of carbon activity in substrate, treatment temperature,kinds of carbides and its structure etc.
A mathematical model of kinetics of carbide layer formed on the surface of steel in fused system was set up with the theory of non-stable diffusion mass transfer and regular solution sub-lattice. This model was analyzed and testified by the experiments in which the VC layers were formed on four kinds of steels as steel 45,4Cr5MoSiV1,T10, and Cr12MoV immersed in the V2O5-Na2O-B2O5 fused system with the reducing agent of silicon.The results showed that there was a good agreement between the model and the experimental results;the growth speed of carbide layer depended on the factors of carbon activity in substrate, treatment temperature,kinds of carbides and its structure etc.
1998, vol. 5, no. 2, pp.
80-83.
Abstract:
By measuring the solubility of nitrogen in BaO-contained and TiO2-contained fluxes at 1623K, the nitride capacity and nitrogen distribution ratio were calculated. Both fluxes had high nitride capacity and nitrogen distribution ratio. The results indicated that Both fluxes treatment were available for denitrogenizing steel. The kinetic studies about denitrogenization showed that nitrogen transfer in liquid steel is the controlled step of denitrogenization reaction, so to improve the mass transfer condition in liquid steel could accelerate the rate of denitrogenization. Under proper test conditions, it was proved to be possible to remove nitrogen over 70 percent from steel with TiO2 contained fluxes.
By measuring the solubility of nitrogen in BaO-contained and TiO2-contained fluxes at 1623K, the nitride capacity and nitrogen distribution ratio were calculated. Both fluxes had high nitride capacity and nitrogen distribution ratio. The results indicated that Both fluxes treatment were available for denitrogenizing steel. The kinetic studies about denitrogenization showed that nitrogen transfer in liquid steel is the controlled step of denitrogenization reaction, so to improve the mass transfer condition in liquid steel could accelerate the rate of denitrogenization. Under proper test conditions, it was proved to be possible to remove nitrogen over 70 percent from steel with TiO2 contained fluxes.
1998, vol. 5, no. 2, pp.
84-86.
Abstract:
Following the basic principle of modem multivariate statistical analysis theory, the description model, prediction model and control model to relate chemical compositions and mechanical properties of steels are introduced. As an example, the total flowchart of components and structure/properties description, prediction and control model for chemical composition and mechanical properties of 20 and A3 steel are presented.
Following the basic principle of modem multivariate statistical analysis theory, the description model, prediction model and control model to relate chemical compositions and mechanical properties of steels are introduced. As an example, the total flowchart of components and structure/properties description, prediction and control model for chemical composition and mechanical properties of 20 and A3 steel are presented.
1998, vol. 5, no. 2, pp.
87-89.
Abstract:
The residual aluminum content has a great influence upon CrNiMoV steel properties and the optimal content is about 0.010%. The aluminum control during the ESR process has been investigated in this paper. All experiments were car ried out in a 20 kg ESR furnace. The results show that when a 60%CaF2-30%Al2O3-5%SiO2-5%CaO slag system and proper deoxidizing schedule is used, a reasonable ingot with optimal aluminum contents can be obtained. Silicon and magnesium contents are approximately the same with those in the electrode.
The residual aluminum content has a great influence upon CrNiMoV steel properties and the optimal content is about 0.010%. The aluminum control during the ESR process has been investigated in this paper. All experiments were car ried out in a 20 kg ESR furnace. The results show that when a 60%CaF2-30%Al2O3-5%SiO2-5%CaO slag system and proper deoxidizing schedule is used, a reasonable ingot with optimal aluminum contents can be obtained. Silicon and magnesium contents are approximately the same with those in the electrode.
1998, vol. 5, no. 2, pp.
90-92.
Abstract:
The equilibrium phase and adiabatic temperature for combustion synthesis of Al2O3/B4C employing Al, B2O3 and C as starting materials is analyzed by both conventional and CALPHAD method. The adiabatic temperature calculed by CALPHAD method is significantly lower than that obtained by conventional method. The CALPHAD calculation also reveals that the equilibrium phases presented at the adiabatic temperature are different to the desired composites. The adiabatic temperature in this system can be lowered by introducing Al2O3 as diluents. The maximum amount of Al2O3 that can be added to the system while maintain a self-sustaining combusion mode is 1.3 mol.
The equilibrium phase and adiabatic temperature for combustion synthesis of Al2O3/B4C employing Al, B2O3 and C as starting materials is analyzed by both conventional and CALPHAD method. The adiabatic temperature calculed by CALPHAD method is significantly lower than that obtained by conventional method. The CALPHAD calculation also reveals that the equilibrium phases presented at the adiabatic temperature are different to the desired composites. The adiabatic temperature in this system can be lowered by introducing Al2O3 as diluents. The maximum amount of Al2O3 that can be added to the system while maintain a self-sustaining combusion mode is 1.3 mol.
1998, vol. 5, no. 2, pp.
93-96.
Abstract:
A novel method has been proposed to remove copper from molten steel by adding the compounds of hydrogen and nitrogen into the melt at normal pressure. Feasibility experiments were carried out in Mo-wire resistance furnace at 1600℃. The copper content of about 400 g 45 steel were reduced from 0.60% and 0.57% to 0.41% and 0.51% with 3.25g and 1.20 g NH4Cl respectively, while the copper contents of about 300 g steel melt were reduced from 1.15% and 0.61% to 0.90% and 0.56% with 4.10 g and 2.00 g NH2CONH2. These results indicate that the proposed method is very promising to be put into practical and worthwhile of further study.
A novel method has been proposed to remove copper from molten steel by adding the compounds of hydrogen and nitrogen into the melt at normal pressure. Feasibility experiments were carried out in Mo-wire resistance furnace at 1600℃. The copper content of about 400 g 45 steel were reduced from 0.60% and 0.57% to 0.41% and 0.51% with 3.25g and 1.20 g NH4Cl respectively, while the copper contents of about 300 g steel melt were reduced from 1.15% and 0.61% to 0.90% and 0.56% with 4.10 g and 2.00 g NH2CONH2. These results indicate that the proposed method is very promising to be put into practical and worthwhile of further study.
1998, vol. 5, no. 2, pp.
97-99.
Abstract:
The reaction kinetics between nitrogen gas and Nd(Fe, Mo)12 intermetallic compound has been studied. The relationship between the reaction temperature, the reaction time with average mass fraction of N in samples have been measured. The activation energy of first step reaction, Ef,(18.2 kJ/mol), is smaller than Es (64.6 kJ/mol) of the second step during which nitrogen diffusion in the range 400~550℃ can be represented by an activated interstitial diffusion process. Heating above 550℃ leads to disproportion of the compound into NdN and α-Fe and the permanent properties will be damaged greatly.
The reaction kinetics between nitrogen gas and Nd(Fe, Mo)12 intermetallic compound has been studied. The relationship between the reaction temperature, the reaction time with average mass fraction of N in samples have been measured. The activation energy of first step reaction, Ef,(18.2 kJ/mol), is smaller than Es (64.6 kJ/mol) of the second step during which nitrogen diffusion in the range 400~550℃ can be represented by an activated interstitial diffusion process. Heating above 550℃ leads to disproportion of the compound into NdN and α-Fe and the permanent properties will be damaged greatly.
1998, vol. 5, no. 2, pp.
99-99.
Abstract:
The dynamics properties of a kind of multi-fingered robot hand is analyzed. It is pointed out that the dynamics property of this kind of multifingered robot hand in the approaching process is quite different from that in the grasping process and,different control algorithm should be taken in the two process. A position-force hybrid control algorithm is proposed which is applied to the control system of the University of Science and Technology Beijing double-thumb robot hand successfully.
The dynamics properties of a kind of multi-fingered robot hand is analyzed. It is pointed out that the dynamics property of this kind of multifingered robot hand in the approaching process is quite different from that in the grasping process and,different control algorithm should be taken in the two process. A position-force hybrid control algorithm is proposed which is applied to the control system of the University of Science and Technology Beijing double-thumb robot hand successfully.
1998, vol. 5, no. 2, pp.
99-99.
Abstract:
The regularity of the development of inclusions and the cleanliness level of the steel 16MnR during the whole process are investigated. The emphasis is focused on the type, quantity, distribution, sources and formation of the large oxide inclusions in ingot. The result shows that the major inclusions in ingot are block Al2O3. The large oxide inclusions mainly come from entrapment of complex slags.
The regularity of the development of inclusions and the cleanliness level of the steel 16MnR during the whole process are investigated. The emphasis is focused on the type, quantity, distribution, sources and formation of the large oxide inclusions in ingot. The result shows that the major inclusions in ingot are block Al2O3. The large oxide inclusions mainly come from entrapment of complex slags.
1998, vol. 5, no. 2, pp.
100-103.
Abstract:
TEM in situ tensile tests of 310 stainless steel show that a dislocation free zone (DFZ) forms if the displacement keeps constant after dislocations are emitted from a crack tip. The elastic DFZ is gradually thinned and the stress in the DFZ will reach the cohesive strength, resulting in nucleation of nanocracks in it and their bluntness into voids. If continuously tensioning, the inhomogeneously thinning ahead of the crack tip, initiating and connecting of microcracks or microvoids will be observed rather than a DFZ, nanocracks' initiation and bluntness into voids. The inverse pile-up ahead of a loaded crack tip can move back to the crack tip when unloading.
TEM in situ tensile tests of 310 stainless steel show that a dislocation free zone (DFZ) forms if the displacement keeps constant after dislocations are emitted from a crack tip. The elastic DFZ is gradually thinned and the stress in the DFZ will reach the cohesive strength, resulting in nucleation of nanocracks in it and their bluntness into voids. If continuously tensioning, the inhomogeneously thinning ahead of the crack tip, initiating and connecting of microcracks or microvoids will be observed rather than a DFZ, nanocracks' initiation and bluntness into voids. The inverse pile-up ahead of a loaded crack tip can move back to the crack tip when unloading.
1998, vol. 5, no. 2, pp.
104-107.
Abstract:
A robot intelligent path planning system(RIPPS), which can be used as a robot off-line programming tool was introduced in this paper. C-space modeling and path search are key parts of the system. A fast C-space modeling is presented based on critical collision joint angle(CCJA), C-obstacle boundary can be computed by the feature points of obstacles. A modified A* algorithm is used for path search, although the path is slightly sub-optimal, a tremendous speed increase is achieved. RIPPS runs on a Silicon Graphic 4D/70 workstation, simulation results show that the system is efficient and practical for robot collision-free autonomous path planning in a structured and known environment.
A robot intelligent path planning system(RIPPS), which can be used as a robot off-line programming tool was introduced in this paper. C-space modeling and path search are key parts of the system. A fast C-space modeling is presented based on critical collision joint angle(CCJA), C-obstacle boundary can be computed by the feature points of obstacles. A modified A* algorithm is used for path search, although the path is slightly sub-optimal, a tremendous speed increase is achieved. RIPPS runs on a Silicon Graphic 4D/70 workstation, simulation results show that the system is efficient and practical for robot collision-free autonomous path planning in a structured and known environment.
1998, vol. 5, no. 2, pp.
108-112.
Abstract:
Automation Gauge Control(AGC) and Automatic Shape Control(ASC) are coupling each other. The coupling models of AGC-ASC synthetic system for the thickness-crown have been established and two artificial neural networks controllers are given. The simulation of computer shows that the AGC-ASC synthetic system can obtain the expected thickness and shape precision with both schemes.
Automation Gauge Control(AGC) and Automatic Shape Control(ASC) are coupling each other. The coupling models of AGC-ASC synthetic system for the thickness-crown have been established and two artificial neural networks controllers are given. The simulation of computer shows that the AGC-ASC synthetic system can obtain the expected thickness and shape precision with both schemes.
1998, vol. 5, no. 2, pp.
113-114.
Abstract:
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