Search2000 Vol. 7, No. 1
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2000, vol. 7, no. 1, pp.
1-4.
Abstract:
Ground subsidence in a Chinese underground gold mine is remarkable. To find out reasons and regularities of the subsidence, following research work was carried out: (1) systemetical investigations of engineering geological conditions, including in situ stress state, location and size of old river beds, ponds and unfilled mined-out areas, (2) in situ monitoring of strata movement by multi-point extensometers in 3 vertical boreholes; (3) FEM (Finite Element Method) analysis to study the relationship between the ground subsidence and mining excavation, especially to inspect the influence of unfilled mined-out areas at shallow depth on the subsidence. Based on the research results, measures to control the ground subsidence and to prevent buildings from damage are provided.
Ground subsidence in a Chinese underground gold mine is remarkable. To find out reasons and regularities of the subsidence, following research work was carried out: (1) systemetical investigations of engineering geological conditions, including in situ stress state, location and size of old river beds, ponds and unfilled mined-out areas, (2) in situ monitoring of strata movement by multi-point extensometers in 3 vertical boreholes; (3) FEM (Finite Element Method) analysis to study the relationship between the ground subsidence and mining excavation, especially to inspect the influence of unfilled mined-out areas at shallow depth on the subsidence. Based on the research results, measures to control the ground subsidence and to prevent buildings from damage are provided.
2000, vol. 7, no. 1, pp.
5-9.
Abstract:
In minerals of mantle xenoliths captured within Tertiary alkali-basalt from Xinchang, Zhejiang province, China, many sulfidemelt inclusions were found by the observation of polished thin section. Electron microprobe analysis has been applied to detect the components of sulfide-melt inclusions. The result shows that the sulfide phases of inclusions are mainly pentlandite, and secondarily pyrrhotite, The molar ratio of Ni to Fe, rNi/rFe, of mineral phases in sulfide inclusions is related to olivine contents in host mantle xenoliths. The rNi/rFe, of sulfides from Xinchang samples has a possitive correlation to r(Fe+Ni)/rS. The r(Fe+Ni)/rS, becomes higher with the increasing of rNi/rFe In single sulfide-melt inclusions, rNi/rFe, r(Fe+Ni)/rS and Ni contents increase from the center to edge, reflecting a result of different cooling speed in an inclusion. A comparison between the data from Hannuoba, West Eifel of Germany and Nograd-Gomor of east Europe suggests that the composition of the inclusions is different for each area, which indicated that a regional differentiation of sulfide in mantle fluids.
In minerals of mantle xenoliths captured within Tertiary alkali-basalt from Xinchang, Zhejiang province, China, many sulfidemelt inclusions were found by the observation of polished thin section. Electron microprobe analysis has been applied to detect the components of sulfide-melt inclusions. The result shows that the sulfide phases of inclusions are mainly pentlandite, and secondarily pyrrhotite, The molar ratio of Ni to Fe, rNi/rFe, of mineral phases in sulfide inclusions is related to olivine contents in host mantle xenoliths. The rNi/rFe, of sulfides from Xinchang samples has a possitive correlation to r(Fe+Ni)/rS. The r(Fe+Ni)/rS, becomes higher with the increasing of rNi/rFe In single sulfide-melt inclusions, rNi/rFe, r(Fe+Ni)/rS and Ni contents increase from the center to edge, reflecting a result of different cooling speed in an inclusion. A comparison between the data from Hannuoba, West Eifel of Germany and Nograd-Gomor of east Europe suggests that the composition of the inclusions is different for each area, which indicated that a regional differentiation of sulfide in mantle fluids.
2000, vol. 7, no. 1, pp.
10-13.
Abstract:
Based on the phase diagrams and the coexistence theory of metallic melts structure involving compound formation, the calculating models of mass action concentrations for Mn-P and Fe-Mn-P melts have been formulated. The calculated mass action concentrations agree well with the corresponding measured activities, this in turn shows that the deduced models can reflect the structural characteristics of the melts concerned and there isn't any saturation of phosphorus in both melts.
Based on the phase diagrams and the coexistence theory of metallic melts structure involving compound formation, the calculating models of mass action concentrations for Mn-P and Fe-Mn-P melts have been formulated. The calculated mass action concentrations agree well with the corresponding measured activities, this in turn shows that the deduced models can reflect the structural characteristics of the melts concerned and there isn't any saturation of phosphorus in both melts.
2000, vol. 7, no. 1, pp.
14-17.
Abstract:
By means of the multi-regressing, the relationship between the sulphur-capacity of refining slag and influence factors (such as slag components, temperature) has been established for CaO-SiO2-Al2O3-MgO slag-system. The real desulphur-capability of this slag and the ideal slag-quantity for desulphurization calculated by regression formula are matched to the practice,
By means of the multi-regressing, the relationship between the sulphur-capacity of refining slag and influence factors (such as slag components, temperature) has been established for CaO-SiO2-Al2O3-MgO slag-system. The real desulphur-capability of this slag and the ideal slag-quantity for desulphurization calculated by regression formula are matched to the practice,
2000, vol. 7, no. 1, pp.
18-23.
Abstract:
Bath smelting reduction for recovering zinc from EAF (Electric Arc Furnace) dust has been investigated in the laboratory. A degree of zinc volatilization of more than 99% was obtained from the process. Temperature has a clear influence on the reduction rate of ZnO in slag. The reduction rate of (ZnO) by [C] is the first order with respect to the content of ZnO in the slag. The apparent activation energy of the (ZnO) reduction reaction is 312 kJ/mol at 1300-1500℃.
Bath smelting reduction for recovering zinc from EAF (Electric Arc Furnace) dust has been investigated in the laboratory. A degree of zinc volatilization of more than 99% was obtained from the process. Temperature has a clear influence on the reduction rate of ZnO in slag. The reduction rate of (ZnO) by [C] is the first order with respect to the content of ZnO in the slag. The apparent activation energy of the (ZnO) reduction reaction is 312 kJ/mol at 1300-1500℃.
2000, vol. 7, no. 1, pp.
24-29.
Abstract:
The shrinkage defect of a ductile iron casting is attributed to the volume variations occurring in solidification, which consist of liquid contraction, solidification shrinkage, graphitization expansion, and mold cavity enlargement. Based on this understanding, a mathematical model for predicting the shrinkage defect of the casting is developed, in which the volume variations of the casting in solidification are numerically simulated, especially, the mold cavity enlargement is quantitatively calculated. Moreover, the reliability of the model is verified in production and experiment.
The shrinkage defect of a ductile iron casting is attributed to the volume variations occurring in solidification, which consist of liquid contraction, solidification shrinkage, graphitization expansion, and mold cavity enlargement. Based on this understanding, a mathematical model for predicting the shrinkage defect of the casting is developed, in which the volume variations of the casting in solidification are numerically simulated, especially, the mold cavity enlargement is quantitatively calculated. Moreover, the reliability of the model is verified in production and experiment.
2000, vol. 7, no. 1, pp.
30-33.
Abstract:
Through the numerical modeling of temperature field for Blast Furnace (BF) lining and stave coolers, it can tell designers how to design a cooler which the hot surface temperature is less than its critical temperature under very high heat flux. Applying low heat resistance lining and staves cooler to BF is good for a layer of slag skull frozen on the hot surface of cooling stave. As long as the slag skull can stand, the furnace wall is stable and the heat loss of furnace does not increase. This is the basic principle for designing long campaignship BF.
Through the numerical modeling of temperature field for Blast Furnace (BF) lining and stave coolers, it can tell designers how to design a cooler which the hot surface temperature is less than its critical temperature under very high heat flux. Applying low heat resistance lining and staves cooler to BF is good for a layer of slag skull frozen on the hot surface of cooling stave. As long as the slag skull can stand, the furnace wall is stable and the heat loss of furnace does not increase. This is the basic principle for designing long campaignship BF.
2000, vol. 7, no. 1, pp.
34-37.
Abstract:
Copper-cadmium halide doped photochromic glass coating on plate glass has been prepared by a sol-gel process. The sample shows reversible photochromic effect. The results of X-ray diffraction (XRD) and infrared (IR) spectrum investigations indicate that the photochromic phase of tile coating is CuBrxCl1-x, solid solution, and that the structure network of the coating is connected with the bonds of Si-O-Si, Si-O-B and Si-O-Al.
Copper-cadmium halide doped photochromic glass coating on plate glass has been prepared by a sol-gel process. The sample shows reversible photochromic effect. The results of X-ray diffraction (XRD) and infrared (IR) spectrum investigations indicate that the photochromic phase of tile coating is CuBrxCl1-x, solid solution, and that the structure network of the coating is connected with the bonds of Si-O-Si, Si-O-B and Si-O-Al.
2000, vol. 7, no. 1, pp.
38-41.
Abstract:
Nanocrystalline copper films were prepared by sputtering and then in situ straining experiments were performed using a transmission electron microscope. Macroscopically, these copper films exhibited very low ductility (<l%). Dislocation activity was limited in regions far from propagating cracks. Near stable growing cracks, considerable local plasticity was observed. The evidence of slip activity both within grain interiors and in grain boundaries was also observed. Although some dislocation; moved very fast, others showed rates much lower than those typically measured for bulk copper. Fracture was intergranular, but not brittle. It occurred by linking of microcracks. Microcracks formed within a micrometer or so ahead of the main crack tip, usually within a grain boundary. Linking then took place by the easiest available path.
Nanocrystalline copper films were prepared by sputtering and then in situ straining experiments were performed using a transmission electron microscope. Macroscopically, these copper films exhibited very low ductility (<l%). Dislocation activity was limited in regions far from propagating cracks. Near stable growing cracks, considerable local plasticity was observed. The evidence of slip activity both within grain interiors and in grain boundaries was also observed. Although some dislocation; moved very fast, others showed rates much lower than those typically measured for bulk copper. Fracture was intergranular, but not brittle. It occurred by linking of microcracks. Microcracks formed within a micrometer or so ahead of the main crack tip, usually within a grain boundary. Linking then took place by the easiest available path.
2000, vol. 7, no. 1, pp.
42-44.
Abstract:
Carbon nitride thin films have been synthesized on polycrystalline Pt substrates using microwave plasma chemical vapor deposition (MPCVD) technique. The N/C atomic ratio is close to the stoichiometric value 1.33 of C3N4. The experimental X-ray diffraction spectra contain all the strong peaks of α-C3N4 and β-C3N4. The films are a mixture of α-C3N4 and β-C3N4. The observed Raman and FT-IR spectra support the existence of C-N covalent bond in carbon nitride compound. The bulk modulus detected by Nano II nanoindentor is up to 349 GPa.
Carbon nitride thin films have been synthesized on polycrystalline Pt substrates using microwave plasma chemical vapor deposition (MPCVD) technique. The N/C atomic ratio is close to the stoichiometric value 1.33 of C3N4. The experimental X-ray diffraction spectra contain all the strong peaks of α-C3N4 and β-C3N4. The films are a mixture of α-C3N4 and β-C3N4. The observed Raman and FT-IR spectra support the existence of C-N covalent bond in carbon nitride compound. The bulk modulus detected by Nano II nanoindentor is up to 349 GPa.
2000, vol. 7, no. 1, pp.
45-47.
Abstract:
In the ZrO2-based ceramic systems doped with different oxides (Y2O3, MgO and Al2O3), the behaviors of electronic and ionic conductivity have been investigated by the quantum chemical SCF-Xα-SW method. The results of the electronic energy spectra and local state density of atoms show that, for the ZrO2 system doped with Al2O3, the energy gap near the Fermi energy level becomes smaller, which implies that the electronic conductivity increases. Since the binding energy between Al and O atoms is increased, the energy for oxygen vacancy migrating is enhanced and the ionic conductivity decreases. In the MxOy-doped ZrO2 systems, due to the doping effect of Al2O3, MgO and Y2O3, the ionic conductivity increases successively, and the electronic conductivity decreases successively. The calculation results are in agreement with that of references and experience.
In the ZrO2-based ceramic systems doped with different oxides (Y2O3, MgO and Al2O3), the behaviors of electronic and ionic conductivity have been investigated by the quantum chemical SCF-Xα-SW method. The results of the electronic energy spectra and local state density of atoms show that, for the ZrO2 system doped with Al2O3, the energy gap near the Fermi energy level becomes smaller, which implies that the electronic conductivity increases. Since the binding energy between Al and O atoms is increased, the energy for oxygen vacancy migrating is enhanced and the ionic conductivity decreases. In the MxOy-doped ZrO2 systems, due to the doping effect of Al2O3, MgO and Y2O3, the ionic conductivity increases successively, and the electronic conductivity decreases successively. The calculation results are in agreement with that of references and experience.
2000, vol. 7, no. 1, pp.
48-50.
Abstract:
To study the electrochemical kinetic properties of the Li/Graphite system, cycle voltammerty (CV), ac-impedance and chronoamperometry (CA) techniques have been used. The results showed that the diffusion of lithium ions in LixC6 is the rate-determining step. The chemical diffusion coefficients of lithium (DLi) have been estimated for different x values. As for the same material, the value of DLi was calculated in order to compare the differences among the three techniques.
To study the electrochemical kinetic properties of the Li/Graphite system, cycle voltammerty (CV), ac-impedance and chronoamperometry (CA) techniques have been used. The results showed that the diffusion of lithium ions in LixC6 is the rate-determining step. The chemical diffusion coefficients of lithium (DLi) have been estimated for different x values. As for the same material, the value of DLi was calculated in order to compare the differences among the three techniques.
2000, vol. 7, no. 1, pp.
51-54.
Abstract:
Stainless steel samples were made by Powder injection Molding (PIM) process with -400 mesh powder in order to investigate the sintering mechanism in this system and develop the PIM of stainless steels. The process included mixing, injection molding, debinding and sintering. Neck growth model was used to analyze the sintering mechanism. The results show that lattice (volume) diffusion is the main mechanism in the sintering process, the products with higher density (>95%) and properties are obtained. At lower temperatures, grain boundary diffusion may play a role in the sintering densification.
Stainless steel samples were made by Powder injection Molding (PIM) process with -400 mesh powder in order to investigate the sintering mechanism in this system and develop the PIM of stainless steels. The process included mixing, injection molding, debinding and sintering. Neck growth model was used to analyze the sintering mechanism. The results show that lattice (volume) diffusion is the main mechanism in the sintering process, the products with higher density (>95%) and properties are obtained. At lower temperatures, grain boundary diffusion may play a role in the sintering densification.
2000, vol. 7, no. 1, pp.
55-57.
Abstract:
Based on the experiments, a new technique of reducing tube with two linked 3-roll roller dies was developed. The external friction conditions, velocity and the non-uniform deformation of metal were distinctly improved, and the friction between metal and tool was decreased. Corrosion strip layers and photo-elastic coatings methods were adopted in the experiment for measuring residual stress, and the residual stresses in the drawn tube with 3-roll dies are reduced.
Based on the experiments, a new technique of reducing tube with two linked 3-roll roller dies was developed. The external friction conditions, velocity and the non-uniform deformation of metal were distinctly improved, and the friction between metal and tool was decreased. Corrosion strip layers and photo-elastic coatings methods were adopted in the experiment for measuring residual stress, and the residual stresses in the drawn tube with 3-roll dies are reduced.
2000, vol. 7, no. 1, pp.
58-62.
Abstract:
By applying genetic algorithms (GA) to on-line identification of linear time-varying systems; a number of modifications are made to the Simple Genetic Algorithm to improve the performance of the algorithm in identification applications. The simulation results indicate that the method is not only capable of following the changing parameters of the system, but also has improved the identification accuracy compared with that using the least square method.
By applying genetic algorithms (GA) to on-line identification of linear time-varying systems; a number of modifications are made to the Simple Genetic Algorithm to improve the performance of the algorithm in identification applications. The simulation results indicate that the method is not only capable of following the changing parameters of the system, but also has improved the identification accuracy compared with that using the least square method.
2000, vol. 7, no. 1, pp.
63-67.
Abstract:
A new structure of ESKD (expert system based on knowledge discovery system KD (D&K)) is first presented on the basis of KD (D&K)-a synthesized knowledge discovery system based on double-base (database and knowledge base) cooperating mechanism. With all new features, ESKD may form a new research direction and provide a great probability for solving the wealth of knowledge in the knowledge base. The general structural frame of ESKD and some sub-systems among ESKD have been described, and the dynamic knowledge base based on double-base cooperating mechanism has been emphased on. According to the result of demonstrative experiment, the structure of ESKD is effective and feasible.
A new structure of ESKD (expert system based on knowledge discovery system KD (D&K)) is first presented on the basis of KD (D&K)-a synthesized knowledge discovery system based on double-base (database and knowledge base) cooperating mechanism. With all new features, ESKD may form a new research direction and provide a great probability for solving the wealth of knowledge in the knowledge base. The general structural frame of ESKD and some sub-systems among ESKD have been described, and the dynamic knowledge base based on double-base cooperating mechanism has been emphased on. According to the result of demonstrative experiment, the structure of ESKD is effective and feasible.
2000, vol. 7, no. 1, pp.
68-71.
Abstract:
A new kind of dynamic neural network—diagonal recurrent neural network (DRNN) and its learning method and architecture are presented. A direct adaptive control scheme is also developed that is applied to a DC (Direct Current) speed control system with the ability to auto-tune PI (Proportion Integral) parameters based on combining DRNN with PI controller. The simulation results of DRNN show better control performances and potential practical use in comparison with PI controller.
A new kind of dynamic neural network—diagonal recurrent neural network (DRNN) and its learning method and architecture are presented. A direct adaptive control scheme is also developed that is applied to a DC (Direct Current) speed control system with the ability to auto-tune PI (Proportion Integral) parameters based on combining DRNN with PI controller. The simulation results of DRNN show better control performances and potential practical use in comparison with PI controller.
2000, vol. 7, no. 1, pp.
72-75.
Abstract:
In order to solve the problem between searching performance and convergence of genetic algorithms, a fast genetic algorithm generalized self-adaptive genetic algorithm (GSAGA) is presented. (1) Evenly distributed initial population is generated. (2) Superior individuals are not broken because of crossover and mutation operation for they are sent to subgeneration directly. (3) High quality immigrants are introduced according to the condition of the population schema. (4) Crossover and mutation are operated on self-adaptation. Therefore, GSAGA solves the coordination problem between convergence and searching performance. In GSAGA, the searching performance and global convergence are greatly improved compared with many existing genetic algorithms. Through simulation, the validity of this modified genetic algorithm is proved.
In order to solve the problem between searching performance and convergence of genetic algorithms, a fast genetic algorithm generalized self-adaptive genetic algorithm (GSAGA) is presented. (1) Evenly distributed initial population is generated. (2) Superior individuals are not broken because of crossover and mutation operation for they are sent to subgeneration directly. (3) High quality immigrants are introduced according to the condition of the population schema. (4) Crossover and mutation are operated on self-adaptation. Therefore, GSAGA solves the coordination problem between convergence and searching performance. In GSAGA, the searching performance and global convergence are greatly improved compared with many existing genetic algorithms. Through simulation, the validity of this modified genetic algorithm is proved.
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