A method is proposed for the analysis of vibration signals from components ofrotating machines, based on the wavelet packet transformation (WPT) and the underlying physicalconcepts of modulation mechanism. The method ...A method is proposed for the analysis of vibration signals from components ofrotating machines, based on the wavelet packet transformation (WPT) and the underlying physicalconcepts of modulation mechanism. The method provides a finer analysis and better time-frequencylocalization capabilities than any other analysis methods. Both details and approximations are splitinto finer components and result in better-localized frequency ranges corresponding to each node ofa wavelet packet tree. For the punpose of feature extraction, a hard threshold is given and theenergy of the coefficients above the threshold is used, as a criterion for the selection of the bestvector. The feature extraction of a vibration signal is accomplished by computing thereconstruction signal and its spectrum. When applied to a rolling bear vibration signal featureextraction, the proposed method can lead to be very effective.展开更多
This paper suggests a scheme of image denoising based on two-dimensional discrete wavelet transform. The denoising algorithm is described with some operators. By thresholding the wavelet transform coefficients of nois...This paper suggests a scheme of image denoising based on two-dimensional discrete wavelet transform. The denoising algorithm is described with some operators. By thresholding the wavelet transform coefficients of noisy images, the original image can be reconstructed correctly. Different threshold selections and thresholding methods are discussed. A new robust local threshold scheme is proposed. Quantifying the performance of image denoising schemes by using the mean square error, the performance of the robust local threshold scheme is demonstrated and is compared with the universal threshold scheme. The experiment shows that image denoising using the robust local threshold performs better than that using the universal threshold.展开更多
Four metal oxide catalysts composed of copper(Cu), stannum(Sn), copper-stannum(Cu-Sn) and copper-cerium(Cu-Ce) respectively were prepared by the co-impregnation method, and γ-alumina(γ-Al 2O 3) is selected as supp...Four metal oxide catalysts composed of copper(Cu), stannum(Sn), copper-stannum(Cu-Sn) and copper-cerium(Cu-Ce) respectively were prepared by the co-impregnation method, and γ-alumina(γ-Al 2O 3) is selected as support. A first-order kinetics model was established to study the catalytic wet air oxidation of phenol at different temperature when these catalysts were used. The model simulations are good agreement with present experimental data. Results showed that the reaction rate constants can be significantly increased when catalysts were used, and the catalyst of 6% Cu—10%Ce/γ-Al 2O 3 showed the best catalytic activity. This is consistent with the result of catalytic wet air oxidation of phenol and the COD removal can be arrived at 98.2% at temperature 210℃, oxygen partial pressure 3 MPa and reaction time 30 min. The activation energies of each reaction with different catalysts are nearly equal, which is found to be about 42 kJ/mol and the reaction in this study is proved to be kinetics control.展开更多
The textures induced by deformation processes of different crafts in air-condition used aluminium 1050H19 foils were measured by using X-ray goniometer. Combining with TEM analysis, effect of texture on deep-drawing p...The textures induced by deformation processes of different crafts in air-condition used aluminium 1050H19 foils were measured by using X-ray goniometer. Combining with TEM analysis, effect of texture on deep-drawing property was discussed. It is show that deformation textures in the specimens, on which four types of rolling-crafts are carried out respectively, are all typical Cu components, and recrystallized R-, Cube-texture don’t exist. Cu-texture is still the predominant component with different orientation density according to different rolling-craft. To specimens which are prone to cracking, their orientation densities of Cu-textures are higher, their textures are stronger and they contain P- and Goss-texture, which are harder to be deformed. The analyses indicat that with the decrease in the rate of reduction/rolling-time and the execution of intermediate holding, textures that are harder to be deformed are eliminated and orientation density of Cu-texture is weakened. Thus, deep-drawing property of aluminium foils is improved.展开更多
Measure index system of technical innovation in medium and smallmanufacturing enterprises is established according to principles of exploration, adaptability,standardization, generalization, feasibility, comparability...Measure index system of technical innovation in medium and smallmanufacturing enterprises is established according to principles of exploration, adaptability,standardization, generalization, feasibility, comparability and combination of economic benefit andcontinual development. It includes index of technical innovation capacity, informationaladministration on technical innovation, and investment of technical innovation, economic benefit,green technical level, social contribution and other influential indexes. Approach to measure oftechnical innovation in medium and small manufacturing enterprises is presented based on combinationof grey relation and fuzzy hiberarchy analysis, and conclusions are drawn based on practicalanalysis of 20 medium and small enterprises, which provides the basis for the medium and smallenterprises to select technical innovation policies and the government to constitute relativepolicies.展开更多
Many attempts have been made to control the regioselectivity for olefin poly- merization by varying the structures of ligands in catalysts. The regioselectivity of propylene polymerization was investigated by replacin...Many attempts have been made to control the regioselectivity for olefin poly- merization by varying the structures of ligands in catalysts. The regioselectivity of propylene polymerization was investigated by replacing a nitrogen atom in the Pd(II) diimine catalyst with an oxygen atom from density functional theory method at the B3LYP/LANL2DZ level. The results show that the 1,2-insertion becomes a rival mechanism to the 2,1-insertion when the nitrogen atom is replaced by the oxygen atom leading to an asymmetric environment in the catalyst, and that the steric effect in the asymmetrical catalyst plays an important part in the polymerization. The insertion barrier from 2-O is much higher than that from 2-N. A pyramid transition state was characterized for the catalyst to convert 2-O back to 2-N through internal rotation. The propylene prefers to coordinate at the opposite side of O in the catalyst. This is the driving force for the internal rotation. The results are significant for isotactic and syndiotactic polymerization.展开更多
Criteria for extreme points and strongly extreme points in Musielak-Orliczsequence spaces, equipped with both the Luxemburg norm and the Orlicz norm, are given.
Properties of symplectic Runge-Kutta (RK) methods and symplectic partitioned Runge-Kutta (PRK) methods with real eigenvalues are discussed in this paper. It is shown that an s stage such method can't reach order m...Properties of symplectic Runge-Kutta (RK) methods and symplectic partitioned Runge-Kutta (PRK) methods with real eigenvalues are discussed in this paper. It is shown that an s stage such method can't reach order more than s+1. Particularly, we prove that no symplectic RK method with real eigenvalues exists in stage s of order s+1 when s is even. But an example constructed by using the W-transformation shows that PRK method of this type does not necessarily meet this order barrier. Another useful way other than W-transformation to construct symplectic PRK method with real eigenvalues is then presented. Finally, a class of efficient symplectic methods is recommended.展开更多
文摘A method is proposed for the analysis of vibration signals from components ofrotating machines, based on the wavelet packet transformation (WPT) and the underlying physicalconcepts of modulation mechanism. The method provides a finer analysis and better time-frequencylocalization capabilities than any other analysis methods. Both details and approximations are splitinto finer components and result in better-localized frequency ranges corresponding to each node ofa wavelet packet tree. For the punpose of feature extraction, a hard threshold is given and theenergy of the coefficients above the threshold is used, as a criterion for the selection of the bestvector. The feature extraction of a vibration signal is accomplished by computing thereconstruction signal and its spectrum. When applied to a rolling bear vibration signal featureextraction, the proposed method can lead to be very effective.
基金Supported by the National Natural Science Foundation of China(No.59775070)
文摘This paper suggests a scheme of image denoising based on two-dimensional discrete wavelet transform. The denoising algorithm is described with some operators. By thresholding the wavelet transform coefficients of noisy images, the original image can be reconstructed correctly. Different threshold selections and thresholding methods are discussed. A new robust local threshold scheme is proposed. Quantifying the performance of image denoising schemes by using the mean square error, the performance of the robust local threshold scheme is demonstrated and is compared with the universal threshold scheme. The experiment shows that image denoising using the robust local threshold performs better than that using the universal threshold.
文摘Four metal oxide catalysts composed of copper(Cu), stannum(Sn), copper-stannum(Cu-Sn) and copper-cerium(Cu-Ce) respectively were prepared by the co-impregnation method, and γ-alumina(γ-Al 2O 3) is selected as support. A first-order kinetics model was established to study the catalytic wet air oxidation of phenol at different temperature when these catalysts were used. The model simulations are good agreement with present experimental data. Results showed that the reaction rate constants can be significantly increased when catalysts were used, and the catalyst of 6% Cu—10%Ce/γ-Al 2O 3 showed the best catalytic activity. This is consistent with the result of catalytic wet air oxidation of phenol and the COD removal can be arrived at 98.2% at temperature 210℃, oxygen partial pressure 3 MPa and reaction time 30 min. The activation energies of each reaction with different catalysts are nearly equal, which is found to be about 42 kJ/mol and the reaction in this study is proved to be kinetics control.
基金supported by Abroad Stwdent Returming Foundation of Heilongjiang(Project LC01C09)supported by Tackle Key Problems of Harbin(Project 0111211108).
文摘The textures induced by deformation processes of different crafts in air-condition used aluminium 1050H19 foils were measured by using X-ray goniometer. Combining with TEM analysis, effect of texture on deep-drawing property was discussed. It is show that deformation textures in the specimens, on which four types of rolling-crafts are carried out respectively, are all typical Cu components, and recrystallized R-, Cube-texture don’t exist. Cu-texture is still the predominant component with different orientation density according to different rolling-craft. To specimens which are prone to cracking, their orientation densities of Cu-textures are higher, their textures are stronger and they contain P- and Goss-texture, which are harder to be deformed. The analyses indicat that with the decrease in the rate of reduction/rolling-time and the execution of intermediate holding, textures that are harder to be deformed are eliminated and orientation density of Cu-texture is weakened. Thus, deep-drawing property of aluminium foils is improved.
基金This project is supported by National Natural Science Foundation of China(No.70171039, No.70131010)Provincial Science Foundation of Heilongjiang, China (No.G01-09).
文摘Measure index system of technical innovation in medium and smallmanufacturing enterprises is established according to principles of exploration, adaptability,standardization, generalization, feasibility, comparability and combination of economic benefit andcontinual development. It includes index of technical innovation capacity, informationaladministration on technical innovation, and investment of technical innovation, economic benefit,green technical level, social contribution and other influential indexes. Approach to measure oftechnical innovation in medium and small manufacturing enterprises is presented based on combinationof grey relation and fuzzy hiberarchy analysis, and conclusions are drawn based on practicalanalysis of 20 medium and small enterprises, which provides the basis for the medium and smallenterprises to select technical innovation policies and the government to constitute relativepolicies.
基金This work was supported by the Natural Science Foundation of Heilongjiang Province (No. B0313) and Research Foundation of China University of Mining and Technology
文摘Many attempts have been made to control the regioselectivity for olefin poly- merization by varying the structures of ligands in catalysts. The regioselectivity of propylene polymerization was investigated by replacing a nitrogen atom in the Pd(II) diimine catalyst with an oxygen atom from density functional theory method at the B3LYP/LANL2DZ level. The results show that the 1,2-insertion becomes a rival mechanism to the 2,1-insertion when the nitrogen atom is replaced by the oxygen atom leading to an asymmetric environment in the catalyst, and that the steric effect in the asymmetrical catalyst plays an important part in the polymerization. The insertion barrier from 2-O is much higher than that from 2-N. A pyramid transition state was characterized for the catalyst to convert 2-O back to 2-N through internal rotation. The propylene prefers to coordinate at the opposite side of O in the catalyst. This is the driving force for the internal rotation. The results are significant for isotactic and syndiotactic polymerization.
基金This research is supported by the National Natural Science Foundation of China(No.10001010)the Youth Foundation of Education Department of Heilongjiang(No.10541099)
文摘Criteria for extreme points and strongly extreme points in Musielak-Orliczsequence spaces, equipped with both the Luxemburg norm and the Orlicz norm, are given.
文摘Properties of symplectic Runge-Kutta (RK) methods and symplectic partitioned Runge-Kutta (PRK) methods with real eigenvalues are discussed in this paper. It is shown that an s stage such method can't reach order more than s+1. Particularly, we prove that no symplectic RK method with real eigenvalues exists in stage s of order s+1 when s is even. But an example constructed by using the W-transformation shows that PRK method of this type does not necessarily meet this order barrier. Another useful way other than W-transformation to construct symplectic PRK method with real eigenvalues is then presented. Finally, a class of efficient symplectic methods is recommended.
