Search2002 Vol. 9, No. 3
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2002, vol. 9, no. 3, pp.
161-165.
Abstract:
Computer simulation was used for hydraulic lifting systems. Based on theory of multiphase flows and their applications on the lifting systems, mathematical models for pump lifting and air lifting were built and simulative analysis programs for them were developed respectively. Corresponding lifting behaviors and system parameters were analyzed and optimum match of the parameters for future pilot mining tests and commercial mining production was predicted.
Computer simulation was used for hydraulic lifting systems. Based on theory of multiphase flows and their applications on the lifting systems, mathematical models for pump lifting and air lifting were built and simulative analysis programs for them were developed respectively. Corresponding lifting behaviors and system parameters were analyzed and optimum match of the parameters for future pilot mining tests and commercial mining production was predicted.
2002, vol. 9, no. 3, pp.
166-169.
Abstract:
Because of poor ground conditions, stoping methods of underhand headings with cemented fill were used in the Jinchuan No. 2 mine, a paste fill system was set up. In order to evaluate the reliability of the new system, investigations and trial running have been done. More than 20 items of modification or improvements related to paste preparation subsystem, pump and pipe subsystem, auto-controlling and monitoring subsystem were finished. The reliability of the paste fill system was analyzed by using the theory of large complex system, and it is useful in reliability study on paste fill system.
Because of poor ground conditions, stoping methods of underhand headings with cemented fill were used in the Jinchuan No. 2 mine, a paste fill system was set up. In order to evaluate the reliability of the new system, investigations and trial running have been done. More than 20 items of modification or improvements related to paste preparation subsystem, pump and pipe subsystem, auto-controlling and monitoring subsystem were finished. The reliability of the paste fill system was analyzed by using the theory of large complex system, and it is useful in reliability study on paste fill system.
2002, vol. 9, no. 3, pp.
170-176.
Abstract:
Based on the phase diagrams, measured activities and the annexation principle, calculating models of mass action concentrations for In-Bi-Cu and In-Sb-Cu melts have been formulated. Calculated results not only agree well with practical values, but also obey the mass action law, showing that the deduced model can reflect the structural reality of given melts and that the annexation principle is applicable to these two ternary metallic melts. So long as there is one from three binary systems constituting the ternary melts, in which the activities of one component exhibit positive deviation relative to Raoultian behavior, heterogeous melts inevitably would form, so heterogeneous calculating model should be used to calculate their mass action concentrations. On the contrary, if all the binary melts are homogeneous and their activities exhibit negative deviation with respect to the Raoult's law, then the ternary melts formed from them will certainly be homogeneous,hence single phase model should be applied.
Based on the phase diagrams, measured activities and the annexation principle, calculating models of mass action concentrations for In-Bi-Cu and In-Sb-Cu melts have been formulated. Calculated results not only agree well with practical values, but also obey the mass action law, showing that the deduced model can reflect the structural reality of given melts and that the annexation principle is applicable to these two ternary metallic melts. So long as there is one from three binary systems constituting the ternary melts, in which the activities of one component exhibit positive deviation relative to Raoultian behavior, heterogeous melts inevitably would form, so heterogeneous calculating model should be used to calculate their mass action concentrations. On the contrary, if all the binary melts are homogeneous and their activities exhibit negative deviation with respect to the Raoult's law, then the ternary melts formed from them will certainly be homogeneous,hence single phase model should be applied.
2002, vol. 9, no. 3, pp.
177-180.
Abstract:
The skin friction and heat transfer occurring in the laminar boundary layer which caused by a vertical liquid jet impinging on a continuously moving horizontal plate were studied. Similarity solutions for shear stress and heat distribution were obtained by using the shooting technique. The results shows that the skin friction decreases with an increase of velocity parameter, the evolving of thermal boundary decrease with increasing in Prandtl number, but increase with increasing of velocity parameter.
The skin friction and heat transfer occurring in the laminar boundary layer which caused by a vertical liquid jet impinging on a continuously moving horizontal plate were studied. Similarity solutions for shear stress and heat distribution were obtained by using the shooting technique. The results shows that the skin friction decreases with an increase of velocity parameter, the evolving of thermal boundary decrease with increasing in Prandtl number, but increase with increasing of velocity parameter.
2002, vol. 9, no. 3, pp.
181-184.
Abstract:
According to the electrical operation and steelmaking theory of EAF, an improved power input procedure of 70t high impedance EAF in Nanjinng Iron and Steel Corp. Ltd. was studied. The investigation method, process and result for use of power supply of high impedance EAF was proposed, and the optimized power-supply curve to EAF steelmaking practice was given, and electrical operation was improved, the electric energy consumption can be reduced by 25 kW·h/t, and power supply time can also be reduced 3 min.
According to the electrical operation and steelmaking theory of EAF, an improved power input procedure of 70t high impedance EAF in Nanjinng Iron and Steel Corp. Ltd. was studied. The investigation method, process and result for use of power supply of high impedance EAF was proposed, and the optimized power-supply curve to EAF steelmaking practice was given, and electrical operation was improved, the electric energy consumption can be reduced by 25 kW·h/t, and power supply time can also be reduced 3 min.
2002, vol. 9, no. 3, pp.
185-187.
Abstract:
The precipitation behavior in Fe-Cu binary alloy was investigated under transmission electron microscope (TEM) during aging at 650℃ for the time range of 100 s to 300 h. In addition to the zones with higher copper content and ε-Cu were observed, a metastable phase with B2-like structure was found in the early stage of the precipitation process, which is quite different from the equilibrium copper phase shown in the Fe-Cu binary phase diagram and has perfect coherent relationship to the α-Fe matrix. The appearance of B2-like structure is very important concerning the mechanism of aging strengthening effect and mechanical properties of corresponding engineering steels and alloys containing copper.
The precipitation behavior in Fe-Cu binary alloy was investigated under transmission electron microscope (TEM) during aging at 650℃ for the time range of 100 s to 300 h. In addition to the zones with higher copper content and ε-Cu were observed, a metastable phase with B2-like structure was found in the early stage of the precipitation process, which is quite different from the equilibrium copper phase shown in the Fe-Cu binary phase diagram and has perfect coherent relationship to the α-Fe matrix. The appearance of B2-like structure is very important concerning the mechanism of aging strengthening effect and mechanical properties of corresponding engineering steels and alloys containing copper.
2002, vol. 9, no. 3, pp.
188-192.
Abstract:
Autoigniting synthesis of gel from Ba(NO3)2, TiO(NO3)2 and C6H8O7·H2O aqueous solution was investigated at an initial temperature of 600℃ and tetragonal BaTiO3 nanopowder with particle size of 80nm was prepared. It is indicated that the specific surface area of the combustion product before and after calcination is 14.74 m2/g and 12.49 m2/g, respectively. The combustion wave is composed of solid phase reaction zone and gaseous phase flame reaction zone. The combustion flame temperature is 1 123 K derived from thermocouple measurement. The characteristics and densification behavior of the sol-gel autoigniting synthesized BaTiO3 nanopowder were investigated.
Autoigniting synthesis of gel from Ba(NO3)2, TiO(NO3)2 and C6H8O7·H2O aqueous solution was investigated at an initial temperature of 600℃ and tetragonal BaTiO3 nanopowder with particle size of 80nm was prepared. It is indicated that the specific surface area of the combustion product before and after calcination is 14.74 m2/g and 12.49 m2/g, respectively. The combustion wave is composed of solid phase reaction zone and gaseous phase flame reaction zone. The combustion flame temperature is 1 123 K derived from thermocouple measurement. The characteristics and densification behavior of the sol-gel autoigniting synthesized BaTiO3 nanopowder were investigated.
2002, vol. 9, no. 3, pp.
193-196.
Abstract:
The influence of processing parameters of relaxation-precipitation-controlling phase transformation (RPC) technique, finish rolling temperature, reduction ratio and relaxing time on the microstructure was studied by thermo-simulation for a low carbon Nb and Ti containing micro-alloyed steel. The microstructure was investigated by optical microscope, transmission electron microscope and electron back scatter diffraction (EBSD). The statistical results of the packet size were calculated. It shows that, after RPC process, the steel is a composite microstructure of bainite and matensite. The best thermo-simulation process for refinement in this experiment is deformation for 30% at 850℃, and then relaxing at this temperature for 60 s to 200 s. Increasing the reduction ratio from 30% to 60% or decreasing the deformation temperature to 800℃ would cause the best relaxation time to become shorter, increasing the deformation temperature to 900℃ would cause the refinement effect to be weak.
The influence of processing parameters of relaxation-precipitation-controlling phase transformation (RPC) technique, finish rolling temperature, reduction ratio and relaxing time on the microstructure was studied by thermo-simulation for a low carbon Nb and Ti containing micro-alloyed steel. The microstructure was investigated by optical microscope, transmission electron microscope and electron back scatter diffraction (EBSD). The statistical results of the packet size were calculated. It shows that, after RPC process, the steel is a composite microstructure of bainite and matensite. The best thermo-simulation process for refinement in this experiment is deformation for 30% at 850℃, and then relaxing at this temperature for 60 s to 200 s. Increasing the reduction ratio from 30% to 60% or decreasing the deformation temperature to 800℃ would cause the best relaxation time to become shorter, increasing the deformation temperature to 900℃ would cause the refinement effect to be weak.
2002, vol. 9, no. 3, pp.
197-201.
Abstract:
A normal spinel LiMn2O4 as cathode material for lithium-ion cells was cycled galvanostatically (0.2C) at 55℃. To determine the contribution of each voltage plateau to the total capacity fading of the cathode upon repeated cycling, the capacities in each plateau were separated by differentiation of voltage vs. capacity. The results show that the capacity fading in the upper voltage plateau is more rapidly than that in the lower during discharging, while in charging process, it fades slower than that in the lower voltage range. The increased capacity shift and aggravated self-discharge/electrolyte oxidation during discharging contribute to a high fading rate in the upper step. Capacity shift also takes place during charging process, which again enhancing the fading rate of the lower voltage plateau. An increase in capacity shift, as a result of an increase in polarization of the cell, plays a major role in determining the fading rate in each voltage plateau, further reflecting the thickening of the passivatio
A normal spinel LiMn2O4 as cathode material for lithium-ion cells was cycled galvanostatically (0.2C) at 55℃. To determine the contribution of each voltage plateau to the total capacity fading of the cathode upon repeated cycling, the capacities in each plateau were separated by differentiation of voltage vs. capacity. The results show that the capacity fading in the upper voltage plateau is more rapidly than that in the lower during discharging, while in charging process, it fades slower than that in the lower voltage range. The increased capacity shift and aggravated self-discharge/electrolyte oxidation during discharging contribute to a high fading rate in the upper step. Capacity shift also takes place during charging process, which again enhancing the fading rate of the lower voltage plateau. An increase in capacity shift, as a result of an increase in polarization of the cell, plays a major role in determining the fading rate in each voltage plateau, further reflecting the thickening of the passivatio
2002, vol. 9, no. 3, pp.
202-205.
Abstract:
The precipitation of ordered α2 phase in a near-α Ti-6.3 Al-4.8Sn-2.0Zr-1.0Mo-0.34Si-0.9Nd (mass fraction) alloy with duplex microstructure, during aging at various temperatures, was investigated. It is concluded that the precipitation and growth of the α2 phase can be controlled by suitable selection of the aging temperature. Aging at higher temperatures can result in the uniform precipitation and growth of α2 ordered phase in αp whereas the α2 ordered phase precipitated only at the lamella boundaries and dislocations in βt. Aging at a moderate temperature can promote the tendency of uniform precipitation of α2 phase in both αp and β1. Aging at a relatively low temperature is suitable for the uniform precipitation and growth of fine α2 particles throughout both the αp and β1, matrix.
The precipitation of ordered α2 phase in a near-α Ti-6.3 Al-4.8Sn-2.0Zr-1.0Mo-0.34Si-0.9Nd (mass fraction) alloy with duplex microstructure, during aging at various temperatures, was investigated. It is concluded that the precipitation and growth of the α2 phase can be controlled by suitable selection of the aging temperature. Aging at higher temperatures can result in the uniform precipitation and growth of α2 ordered phase in αp whereas the α2 ordered phase precipitated only at the lamella boundaries and dislocations in βt. Aging at a moderate temperature can promote the tendency of uniform precipitation of α2 phase in both αp and β1. Aging at a relatively low temperature is suitable for the uniform precipitation and growth of fine α2 particles throughout both the αp and β1, matrix.
2002, vol. 9, no. 3, pp.
206-211.
Abstract:
By means of deformation and long term aging, the stability and phase equilibrim characteristic of the C+N synthetically strengthening austenitic Fe-Cr-Mn (W,V) alloy were investigated. Experimental results indicate that the austenitic alloy remains stability and no γ→α transformation occurs under 500℃. Synthetic addition of C and N causes the grains to refine and powerfully retards formation of ε martensite and precipitation of σ phase. Ms point is elevated with long term aging at elevated temperature (500-700℃) due to a large number of strain induced carbides precipitate. Along with accelerated decomposition of strain induced α' martensite and occurrence of recrystallization, γ→α transformation and σ phase precipitation are promoted so that austenite becomes unstable.
By means of deformation and long term aging, the stability and phase equilibrim characteristic of the C+N synthetically strengthening austenitic Fe-Cr-Mn (W,V) alloy were investigated. Experimental results indicate that the austenitic alloy remains stability and no γ→α transformation occurs under 500℃. Synthetic addition of C and N causes the grains to refine and powerfully retards formation of ε martensite and precipitation of σ phase. Ms point is elevated with long term aging at elevated temperature (500-700℃) due to a large number of strain induced carbides precipitate. Along with accelerated decomposition of strain induced α' martensite and occurrence of recrystallization, γ→α transformation and σ phase precipitation are promoted so that austenite becomes unstable.
2002, vol. 9, no. 3, pp.
212-215.
Abstract:
The microstructure of CaO-P2O5-SiO2-MgO-F glass-ceramics during crystallization were investigated and the crystallized phases were identified with DTA (Differential Thermal Analysis), SEM (Scanning Electron Microscope) and XRD (X-ray Diffraction) techniques. The mechanical properties such as bending strength and fracture toughness, as well as their changes with advancing crystallization were determined. The results show that the changes of the mechanical properties are correlated with the microstructures. The sample heated up to 810℃ and soaked for 4h has smaller crystalline size and less volum fraction of fluorophlogopite, so it has higher bending strength (about 190 MPa), and higher crack toughness (about 2.63 MPa·m12).
The microstructure of CaO-P2O5-SiO2-MgO-F glass-ceramics during crystallization were investigated and the crystallized phases were identified with DTA (Differential Thermal Analysis), SEM (Scanning Electron Microscope) and XRD (X-ray Diffraction) techniques. The mechanical properties such as bending strength and fracture toughness, as well as their changes with advancing crystallization were determined. The results show that the changes of the mechanical properties are correlated with the microstructures. The sample heated up to 810℃ and soaked for 4h has smaller crystalline size and less volum fraction of fluorophlogopite, so it has higher bending strength (about 190 MPa), and higher crack toughness (about 2.63 MPa·m12).
2002, vol. 9, no. 3, pp.
216-220.
Abstract:
A Cu/Al galvanic couple was established to study the influence of the oxidant KMnO4 on the film-forming process of rare earth metal (REM) conversion coating on LY12 aluminum alloy. It is found that the galvanic couple simulative experiment accords with the actual immersion, and it can be substantially used to simulate the behavior of LY12 aluminum alloy in the film-forming process. It is showed that the formation of the coating is quickened in CeCl3 solution containing KMnO4 compared with that not containing KMnO4. XPS results reveal that the coating formed on cathode is composed of oxide or hydroxide of Ce and Mn, so the mechanism of formation of REM conversion coating changes when KMnO4 is added.
A Cu/Al galvanic couple was established to study the influence of the oxidant KMnO4 on the film-forming process of rare earth metal (REM) conversion coating on LY12 aluminum alloy. It is found that the galvanic couple simulative experiment accords with the actual immersion, and it can be substantially used to simulate the behavior of LY12 aluminum alloy in the film-forming process. It is showed that the formation of the coating is quickened in CeCl3 solution containing KMnO4 compared with that not containing KMnO4. XPS results reveal that the coating formed on cathode is composed of oxide or hydroxide of Ce and Mn, so the mechanism of formation of REM conversion coating changes when KMnO4 is added.
2002, vol. 9, no. 3, pp.
221-223.
Abstract:
In order to get high quality of products, the combustion of aluminium-iron oxide thermite in SHS-gravitational process must be under control. The effects of thermite filling density, hole in thermite and inclined angle of pipe on combustion rate were studied. It shows that the combustion rate decreases with the decrease of filling density. The thermite combusts downwards the pipe much more quickly if there are holes in the thermite. And the combustion rate increases with the increase of the inclined angle of pipe. The experiment results show that the combustion of thermite is predominantly controlled by gas phase reaction, which is attributed to the high temperature of the thermite combustion.
In order to get high quality of products, the combustion of aluminium-iron oxide thermite in SHS-gravitational process must be under control. The effects of thermite filling density, hole in thermite and inclined angle of pipe on combustion rate were studied. It shows that the combustion rate decreases with the decrease of filling density. The thermite combusts downwards the pipe much more quickly if there are holes in the thermite. And the combustion rate increases with the increase of the inclined angle of pipe. The experiment results show that the combustion of thermite is predominantly controlled by gas phase reaction, which is attributed to the high temperature of the thermite combustion.
2002, vol. 9, no. 3, pp.
224-227.
Abstract:
Employing Simulated Annealing Algorithm (SAA) and many measured data, a calculation model of work roll wear was built in the 2 800mm 4-high mill of Wuhan Iron and Steel (Group) Co.(WlSCO). The model was a semi-theory practical formula. Its pattern and magnitude were still hardly defined with classical optimization methods. But the problem could be resolved by SAA. It was pretty high precision to predict the values for the wear profiles of work roll in a rolling unit. After one-year application, the results show that the model is feasible in engineering, and it can be applied to predict the wear profiles of work roll in other mills
Employing Simulated Annealing Algorithm (SAA) and many measured data, a calculation model of work roll wear was built in the 2 800mm 4-high mill of Wuhan Iron and Steel (Group) Co.(WlSCO). The model was a semi-theory practical formula. Its pattern and magnitude were still hardly defined with classical optimization methods. But the problem could be resolved by SAA. It was pretty high precision to predict the values for the wear profiles of work roll in a rolling unit. After one-year application, the results show that the model is feasible in engineering, and it can be applied to predict the wear profiles of work roll in other mills
2002, vol. 9, no. 3, pp.
228-232.
Abstract:
Though progress has been made in fractal compression techniques, the long encoding times still remain the main drawback of this technique, which results from the need of performing a large number of range-domain matches. The total encoding time is the sum of the time required to perform each match. In order to make this method more efficient in practical use, the fuzzy theory based on feature extraction of the projection and normalized codebook method has been provided to optimize the encoding time, based on the c-means clustering approach. The results of the implementation of Rate Mean Square (RMS), Peak signal noise ratio (PSNR) and the encoding time of this proposed method have been compared to other methods like the Feature Extraction and Self-orgarnization methods to show its efficiency.
Though progress has been made in fractal compression techniques, the long encoding times still remain the main drawback of this technique, which results from the need of performing a large number of range-domain matches. The total encoding time is the sum of the time required to perform each match. In order to make this method more efficient in practical use, the fuzzy theory based on feature extraction of the projection and normalized codebook method has been provided to optimize the encoding time, based on the c-means clustering approach. The results of the implementation of Rate Mean Square (RMS), Peak signal noise ratio (PSNR) and the encoding time of this proposed method have been compared to other methods like the Feature Extraction and Self-orgarnization methods to show its efficiency.
2002, vol. 9, no. 3, pp.
233-236.
Abstract:
On the basis of integrating two-dimensional varying thickness finite element method with hybrid genetic algorithm, a precise model was developed to design ideal backup roll contour (Varying Contact Backup Roll, in short VCR) in finishing trains of hot rolling rapidly and efficaciously. Additionally, a lot of good actual effects of VCR, such as evident improvement of profile and flatness of strip, remarkable decrease of roll consume, excellent maneuverability and maintenance, and so on, were validated by long-term industrial tests in hot rolling strip plant of Wuhan Iron and Steel Group Corporation (WISCO).
On the basis of integrating two-dimensional varying thickness finite element method with hybrid genetic algorithm, a precise model was developed to design ideal backup roll contour (Varying Contact Backup Roll, in short VCR) in finishing trains of hot rolling rapidly and efficaciously. Additionally, a lot of good actual effects of VCR, such as evident improvement of profile and flatness of strip, remarkable decrease of roll consume, excellent maneuverability and maintenance, and so on, were validated by long-term industrial tests in hot rolling strip plant of Wuhan Iron and Steel Group Corporation (WISCO).
2002, vol. 9, no. 3, pp.
237-240.
Abstract:
A new algorithm for the knowledge discovery based on statistic induction logic is proposed, and the validity of the method is verified by examples. The method is suitable for a large range of knowledge discovery applications in the studying of causal relation, uncertainty knowledge acquisition and principal factors analyzing. The language field description of the state space makes the algorithm robust in the adaptation with easier understandable results, which are isomotopy with natural language in the topologic space.
A new algorithm for the knowledge discovery based on statistic induction logic is proposed, and the validity of the method is verified by examples. The method is suitable for a large range of knowledge discovery applications in the studying of causal relation, uncertainty knowledge acquisition and principal factors analyzing. The language field description of the state space makes the algorithm robust in the adaptation with easier understandable results, which are isomotopy with natural language in the topologic space.
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