Search2002 Vol. 9, No. 1
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2002, vol. 9, no. 1, pp.
1-4.
Abstract:
The nonlinear dynamical behaviors of artificial neural network (ANN) and their application to science and engineering were summarized. The mechanism of two kinds of dynamical processes, i.e. weight dynamics and activation dynamics in neural networks, and the stability of computing in structural analysis and design were stated briefly. It was successfully applied to nonlinear neural network to evaluate the stability of underground stope structure in a gold mine. With the application of BP network, it is proven that the neuro-com-puting is a practical and advanced tool for solving large-scale underground rock engineering problems.
The nonlinear dynamical behaviors of artificial neural network (ANN) and their application to science and engineering were summarized. The mechanism of two kinds of dynamical processes, i.e. weight dynamics and activation dynamics in neural networks, and the stability of computing in structural analysis and design were stated briefly. It was successfully applied to nonlinear neural network to evaluate the stability of underground stope structure in a gold mine. With the application of BP network, it is proven that the neuro-com-puting is a practical and advanced tool for solving large-scale underground rock engineering problems.
2002, vol. 9, no. 1, pp.
5-8.
Abstract:
By simulating test and study in laboratory, the structure and performance of frothing generator were determined. The relative curves between the frothing volume and gas velocity of foaming net, supplying liquid volume and the content of foaming agent were obtained respectively. There were an optimum gas-velocity of foaming net, an optimum supplying liquid volume and an optimum content of foaming agent under the condition of the given material quality and shape of foaming net and spraying form. The spraying froth is of a great assistance in collecting respirable dust.
By simulating test and study in laboratory, the structure and performance of frothing generator were determined. The relative curves between the frothing volume and gas velocity of foaming net, supplying liquid volume and the content of foaming agent were obtained respectively. There were an optimum gas-velocity of foaming net, an optimum supplying liquid volume and an optimum content of foaming agent under the condition of the given material quality and shape of foaming net and spraying form. The spraying froth is of a great assistance in collecting respirable dust.
2002, vol. 9, no. 1, pp.
9-12.
Abstract:
The hot ductility of the V-containing micro-alloying steel CC (continuous casting) slabs and precipitation of vanadium carbide in the tensile specimens were investigated. There sults indicate that the precipitation ratio and precipitation rate of vanadium in the specimens reach maximum respectively at 900, -825 and 825℃. There is still l0%-l7% of vanadium precipitated when the deformation temperature decreases to 800-700℃. Vanadium largely affects the ductility of the steel in the low ductility temperature Region III. Embrittlement of steel with higher V content is severer in the region and the embrittlement extends to lower temperature.
The hot ductility of the V-containing micro-alloying steel CC (continuous casting) slabs and precipitation of vanadium carbide in the tensile specimens were investigated. There sults indicate that the precipitation ratio and precipitation rate of vanadium in the specimens reach maximum respectively at 900, -825 and 825℃. There is still l0%-l7% of vanadium precipitated when the deformation temperature decreases to 800-700℃. Vanadium largely affects the ductility of the steel in the low ductility temperature Region III. Embrittlement of steel with higher V content is severer in the region and the embrittlement extends to lower temperature.
2002, vol. 9, no. 1, pp.
13-15.
Abstract:
Tundish is an important metallurgical reactor in the continuous casting process. In order to control the fluid flow in tundish and thus take full advantage of the residencetime available for the removal of inclusions from molten steel, the effect of weir and dam on the fluid flow has been studied in a water model based on the characteristic number Froude and Reynold number similarity criteria. The residence time distribution curves of the flow were measured by SG800. The optimum arrangement of darn and weir and the nonstationary flow in tundish were discussed. The results show that the combination of weir and dam is benefit for the flow pattern in tundish, weir can prevent the upper recirculating flow, dam can cut off the bottom flow and turn to upwards, it is advantageous to separate the nonmetallic inclusions. Furthermore, it is important to exceed the critical depth of bath during exchange ladles, not only for the inclusion floatation but also for avoiding tundish slag drainage earlier.
Tundish is an important metallurgical reactor in the continuous casting process. In order to control the fluid flow in tundish and thus take full advantage of the residencetime available for the removal of inclusions from molten steel, the effect of weir and dam on the fluid flow has been studied in a water model based on the characteristic number Froude and Reynold number similarity criteria. The residence time distribution curves of the flow were measured by SG800. The optimum arrangement of darn and weir and the nonstationary flow in tundish were discussed. The results show that the combination of weir and dam is benefit for the flow pattern in tundish, weir can prevent the upper recirculating flow, dam can cut off the bottom flow and turn to upwards, it is advantageous to separate the nonmetallic inclusions. Furthermore, it is important to exceed the critical depth of bath during exchange ladles, not only for the inclusion floatation but also for avoiding tundish slag drainage earlier.
2002, vol. 9, no. 1, pp.
16-19.
Abstract:
Based on the current situation of studying the thermodynamic property of Fe-C-Cr melt using the carbon saturated solubility, an experimental data treatment method of the carbon saturated solubility was put forward. With this method a linear relationship ex-pression of the carbon saturated solubility in Fe-C-Cr melt was obtained, which intercept is dependent on temperature and independent of third component[Cr], but which slope is dependent on third component[Cr] and independent of temperature. Through this expression activity interaction coefficients at different temperatures were calculated and the relationship between activity interaction coefficients and temperature is also obtained.
Based on the current situation of studying the thermodynamic property of Fe-C-Cr melt using the carbon saturated solubility, an experimental data treatment method of the carbon saturated solubility was put forward. With this method a linear relationship ex-pression of the carbon saturated solubility in Fe-C-Cr melt was obtained, which intercept is dependent on temperature and independent of third component[Cr], but which slope is dependent on third component[Cr] and independent of temperature. Through this expression activity interaction coefficients at different temperatures were calculated and the relationship between activity interaction coefficients and temperature is also obtained.
2002, vol. 9, no. 1, pp.
20-24.
Abstract:
The application of the optimal sinter burden design in the sinter shop of No.1 Iron-making Plant in Tangshan Iron & Steel Corp was reported. By using burden calculation and simulating production under different situations, it is demonstrated that the technology can providethe relevant information in product quality and cost etc. for decision-makers. The technology has been used to guide production of the Sinter Shop since 2000, and a remarkable achievement has been obtained.
The application of the optimal sinter burden design in the sinter shop of No.1 Iron-making Plant in Tangshan Iron & Steel Corp was reported. By using burden calculation and simulating production under different situations, it is demonstrated that the technology can providethe relevant information in product quality and cost etc. for decision-makers. The technology has been used to guide production of the Sinter Shop since 2000, and a remarkable achievement has been obtained.
2002, vol. 9, no. 1, pp.
25-30.
Abstract:
Both parallel and staggered plate fin arrays have shown promise for use in high performance heat sinks regard of its individual manufacturing costs. The geometrical and operational parameters are very important to their cooling performance as heat sinks in practical applications. Fluent 5.0 commercial CFD (computational fluid dynamic) code is used to simulate the flow and heat transfer of those heat sinks of different realistic parameters. Based on those simulations, two correlations, concerning Nusselt number and friction factor as the functions of geometrical and operational parameters, FB (fin-base area ratio), PR' (ratio of spanwise pitch tolengthwise pitch) and Re, were developed. From the both, the performance comparisons for optimizing geometrical and operational parameters of a fixed dimension heat sink are shown at constant pumping power and constant thermal resistance. Several optimized parameters were obtained can out perform the staggered ones.
Both parallel and staggered plate fin arrays have shown promise for use in high performance heat sinks regard of its individual manufacturing costs. The geometrical and operational parameters are very important to their cooling performance as heat sinks in practical applications. Fluent 5.0 commercial CFD (computational fluid dynamic) code is used to simulate the flow and heat transfer of those heat sinks of different realistic parameters. Based on those simulations, two correlations, concerning Nusselt number and friction factor as the functions of geometrical and operational parameters, FB (fin-base area ratio), PR' (ratio of spanwise pitch tolengthwise pitch) and Re, were developed. From the both, the performance comparisons for optimizing geometrical and operational parameters of a fixed dimension heat sink are shown at constant pumping power and constant thermal resistance. Several optimized parameters were obtained can out perform the staggered ones.
2002, vol. 9, no. 1, pp.
31-35.
Abstract:
The SCC (stress corrosion cracking) susceptibility of steel l6Mn in nitrate solution was studied. The results showed that applied potential polarization would accelerate(anodic polarization) or retard (cathodic polarization) the SCC process. The study on phase electrochemistry revealed that there was significant difference in electrochemical performance between ferrite and pearlite of steel 16Mn. Pearlite preferentially corroded under the action of galvanic cell. The observation on time and in situ showed that corrosion started first at the phaseboundary between ferrite and pearlite, and the pearlite gradually corroded until disappeared, and then corrosion crossed the phase boundary extending into the ferrite phase. According to this, an anodic dissolution mechanism of SCC was proposed, on which pre-existing sting active path and phase electrochemistry (PEAP-PEC) jointly came into action (SCC mechanism of PEAP-PEC).
The SCC (stress corrosion cracking) susceptibility of steel l6Mn in nitrate solution was studied. The results showed that applied potential polarization would accelerate(anodic polarization) or retard (cathodic polarization) the SCC process. The study on phase electrochemistry revealed that there was significant difference in electrochemical performance between ferrite and pearlite of steel 16Mn. Pearlite preferentially corroded under the action of galvanic cell. The observation on time and in situ showed that corrosion started first at the phaseboundary between ferrite and pearlite, and the pearlite gradually corroded until disappeared, and then corrosion crossed the phase boundary extending into the ferrite phase. According to this, an anodic dissolution mechanism of SCC was proposed, on which pre-existing sting active path and phase electrochemistry (PEAP-PEC) jointly came into action (SCC mechanism of PEAP-PEC).
2002, vol. 9, no. 1, pp.
36-39.
Abstract:
A novel open-framework vanadium(W) phosphate(H3NCH2CH2NH3)3[(VO)4(PP4)2(HPO4)4] (short for V2P3-en) has been prepared. It issynthesized hydrothermally in the presence of ethylenediamine (en) at 170℃ for 5 days byself-assembly from structurally simple precursors V2O5, H3PO4 and H2O. The compound ischaracterized by means of Fourier transform-infrared spectroscopy (FT-IR),Thermogravimetry-differential thermal analysis (TG-DTA), X-ray powder diffraction analysis (XRD) andScanning electron microscopy (SEM). Furthermore, the composition-structure-thermal stabilityrelation of V2P3-en is explored in terms of crystal chemistry, and the potential approach to theenhancement of its thermal stability is proposed.
A novel open-framework vanadium(W) phosphate(H3NCH2CH2NH3)3[(VO)4(PP4)2(HPO4)4] (short for V2P3-en) has been prepared. It issynthesized hydrothermally in the presence of ethylenediamine (en) at 170℃ for 5 days byself-assembly from structurally simple precursors V2O5, H3PO4 and H2O. The compound ischaracterized by means of Fourier transform-infrared spectroscopy (FT-IR),Thermogravimetry-differential thermal analysis (TG-DTA), X-ray powder diffraction analysis (XRD) andScanning electron microscopy (SEM). Furthermore, the composition-structure-thermal stabilityrelation of V2P3-en is explored in terms of crystal chemistry, and the potential approach to theenhancement of its thermal stability is proposed.
2002, vol. 9, no. 1, pp.
40-44.
Abstract:
Kinetics of carbothermic reduction of manganese oxide and the catalyticeffect of La2O3 on the reduction have been studied by the measurement of mass loss in N2 atmosphere at different temperatures and followed by SEM analysis. It is concluded that the kinetics of carbothermic reduction of manganese oxide is divided into three stages:gas diffusion controlling stage, carbon gasification con-trolling stage and solid state diffusion controlling stage. La2O3 has catalytic effect on the reduction. The catalytic effect of La2O3 increases withthe added amount of La2O3. SEM analysis shows that the catalytic mechanism is that La2O3promotes the transfer of oxygen ions so that carbon gasifying is catalyzed and thus carbothermic reduction of MnO2 is catalyzed.
Kinetics of carbothermic reduction of manganese oxide and the catalyticeffect of La2O3 on the reduction have been studied by the measurement of mass loss in N2 atmosphere at different temperatures and followed by SEM analysis. It is concluded that the kinetics of carbothermic reduction of manganese oxide is divided into three stages:gas diffusion controlling stage, carbon gasification con-trolling stage and solid state diffusion controlling stage. La2O3 has catalytic effect on the reduction. The catalytic effect of La2O3 increases withthe added amount of La2O3. SEM analysis shows that the catalytic mechanism is that La2O3promotes the transfer of oxygen ions so that carbon gasifying is catalyzed and thus carbothermic reduction of MnO2 is catalyzed.
2002, vol. 9, no. 1, pp.
45-47.
Abstract:
The Ni81Fe19/Ta films with different NiFe thickness were prepared at different base vacuums and sputtering pressures. The results of magnetic measurement and atomic force microscope (AFM) showed that the films prepared at higher base vacuum and lower sputtering pressure had larger △R/R. The reason should be that higher base vacuum and lower sputtering pressure introduce larger grainsize and lower surface roughness, which will weaken the scattering of electrons, reduce the resistance R, and increase △R/R.
The Ni81Fe19/Ta films with different NiFe thickness were prepared at different base vacuums and sputtering pressures. The results of magnetic measurement and atomic force microscope (AFM) showed that the films prepared at higher base vacuum and lower sputtering pressure had larger △R/R. The reason should be that higher base vacuum and lower sputtering pressure introduce larger grainsize and lower surface roughness, which will weaken the scattering of electrons, reduce the resistance R, and increase △R/R.
2002, vol. 9, no. 1, pp.
48-52.
Abstract:
A novel process termed low-temperature combustion-synthesis (LCS) of Ba(NO3)2-TiO2-C6H8O7.centre dot H2O system was investigated at the initial temperature of 600℃ and ultrafine BaTiO3 powders with a particle size of 200-350 nm were prepared. It was found that the molar ratio of NO3-/citric acid and the homogeneity of combustion have remarkable effect on the characteristics of the powder. The reaction mechanism of LCS BaTiO3 powders was proposed on the basis of thermodynamic analysis.
A novel process termed low-temperature combustion-synthesis (LCS) of Ba(NO3)2-TiO2-C6H8O7.centre dot H2O system was investigated at the initial temperature of 600℃ and ultrafine BaTiO3 powders with a particle size of 200-350 nm were prepared. It was found that the molar ratio of NO3-/citric acid and the homogeneity of combustion have remarkable effect on the characteristics of the powder. The reaction mechanism of LCS BaTiO3 powders was proposed on the basis of thermodynamic analysis.
2002, vol. 9, no. 1, pp.
53-58.
Abstract:
Based on pair potential, the Bragg Williams (B-W) model is modified to take into account the effect of the lattice parameter on theoretical order-disorder transformation analysis. The main purpose of this work is to understand the basic aspects of this effect and related reasonable model on order-disorder transformation. In the present approach, the configuration free energy is chosen as function of the lattice parameter and the long-range order.This energy is calculated through Taylor's expansion, starting from the disordered state. It was found that the configuration free energy has been strongly modified when the lattice parameter is taken into account. It was also found only one type of order-disorder transformation exists in AB alloy and three kinds of order-disorder transformations for non-equiatomic alloy system such as A3B alloy. This result is in agreement with experiments.
Based on pair potential, the Bragg Williams (B-W) model is modified to take into account the effect of the lattice parameter on theoretical order-disorder transformation analysis. The main purpose of this work is to understand the basic aspects of this effect and related reasonable model on order-disorder transformation. In the present approach, the configuration free energy is chosen as function of the lattice parameter and the long-range order.This energy is calculated through Taylor's expansion, starting from the disordered state. It was found that the configuration free energy has been strongly modified when the lattice parameter is taken into account. It was also found only one type of order-disorder transformation exists in AB alloy and three kinds of order-disorder transformations for non-equiatomic alloy system such as A3B alloy. This result is in agreement with experiments.
2002, vol. 9, no. 1, pp.
59-64.
Abstract:
A quasi three dimensions molecular dynamic method was used to simulate the effect of hydrogen on dislocation emission and crack propagation in nickel. In situ observation in a transmission electron microscope (TEM) was used to confirm the simulation results. The simulation result indicated that hydrogen solubilized in nickel decreased the critical stress intensity for the dislocation emission, i.e., hydrogen enhanced dislocation emission. In situ observation in TEM showed that hydrogen enhanced dislocation emission and motion before the initiation of hydrogen-induced crack.
A quasi three dimensions molecular dynamic method was used to simulate the effect of hydrogen on dislocation emission and crack propagation in nickel. In situ observation in a transmission electron microscope (TEM) was used to confirm the simulation results. The simulation result indicated that hydrogen solubilized in nickel decreased the critical stress intensity for the dislocation emission, i.e., hydrogen enhanced dislocation emission. In situ observation in TEM showed that hydrogen enhanced dislocation emission and motion before the initiation of hydrogen-induced crack.
2002, vol. 9, no. 1, pp.
65-73.
Abstract:
Presents analytic criteria for the local activity theory in two-port cellular neural network (CNN) cells with four local state variables, and gives the application to a smoothed Chua's circuit (SCC) CNN with two-port and 15×15 arrays. The bifurcation diagrams of the SCC CNN show that they are completely the same as those of an SCC CNN with one-port calculated earlier;which do not exist locally passive domain. The evolution of the patterns of the state variables of the SCC CNN is stimulated. Oscillatory patterns, chaotic patterns, or divergent patterns may emerge if the selected cell parameters are located in the locally active unstable domains but nearby the edge of chaos domain.
Presents analytic criteria for the local activity theory in two-port cellular neural network (CNN) cells with four local state variables, and gives the application to a smoothed Chua's circuit (SCC) CNN with two-port and 15×15 arrays. The bifurcation diagrams of the SCC CNN show that they are completely the same as those of an SCC CNN with one-port calculated earlier;which do not exist locally passive domain. The evolution of the patterns of the state variables of the SCC CNN is stimulated. Oscillatory patterns, chaotic patterns, or divergent patterns may emerge if the selected cell parameters are located in the locally active unstable domains but nearby the edge of chaos domain.
2002, vol. 9, no. 1, pp.
74-77.
Abstract:
MDM (minimum distance method) is a very popular algorithm in state recognition. But it has a presupposition, that is, the distance within one class must be shorter enough than the distance between classes. When this presupposition is not satisfied, the method is no longer valid. In order to overcome the shortcomings of MDM, an improved minimum distance method(IMDM) based on ANN (artificial neural networks) is presented. The simulation results demonstrate that IMDM has two advantages, that is, the rate of recognition is faster and the accuracy of recognition is higher compared with MDM.
MDM (minimum distance method) is a very popular algorithm in state recognition. But it has a presupposition, that is, the distance within one class must be shorter enough than the distance between classes. When this presupposition is not satisfied, the method is no longer valid. In order to overcome the shortcomings of MDM, an improved minimum distance method(IMDM) based on ANN (artificial neural networks) is presented. The simulation results demonstrate that IMDM has two advantages, that is, the rate of recognition is faster and the accuracy of recognition is higher compared with MDM.
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