Bring forward a new analytical method in order to evaluate the stability of the process of aluminum alloy pulsed MIG welding. The ratio of the first and the second peak in arc voltage signal probability density was se...Bring forward a new analytical method in order to evaluate the stability of the process of aluminum alloy pulsed MIG welding. The ratio of the first and the second peak in arc voltage signal probability density was selected to evaluate aluminum alloy pulse MIG welding stability. By calculating the arc voltage signal probability density from 80 sets of welding experiments, the ratio of the two peaks in arc voltage probability in every set was captured. And the evaluation system of aluminum alloy pulse MIG welding stability was established. The smaller the ratio of peaks in arc voltage signal probability density is, the better the stability of the welding will be;the bigger the ratio of peaks in arc voltage signal probability density is, the poorer the stability of the welding will be.展开更多
A Reynolds stress closure based on the generalized Langevin model (GLM), developed by Haworth and Pope, is applied to the flow calculation with swirl-induced recirculation. The purpose of the work is to assess the per...A Reynolds stress closure based on the generalized Langevin model (GLM), developed by Haworth and Pope, is applied to the flow calculation with swirl-induced recirculation. The purpose of the work is to assess the performance of this model under the complex flow conditions caused by the presence of strong swirl which gives rise to both unconventional recirculation in the vicinity of the symmetry axis and strong anisotropy in the turbulence field. Comparison of the computational results are made both with the experimental data of Roback and Johnson and the computational results obtained with the typical isotropization of production model (IPM) and the k-∈ type Boussinesq viscosity model.展开更多
A kind of new method in measuring data processing called maximum entropy method(MEM) is introduced. The probability-density function (pdf) is deduced by MEM under the restraint of the square of the data. A group of ex...A kind of new method in measuring data processing called maximum entropy method(MEM) is introduced. The probability-density function (pdf) is deduced by MEM under the restraint of the square of the data. A group of experiment data is processed using the method and the result closed to the real distribution is got. The different pdf got under different order of square and by different content of samples is discussed. It draws conclusions that the pdf in the square restrain with more order than three using MEM can give the distribution of the data basically, and it is not suitable to use the square restraint of data when the samples are less.展开更多
文摘Bring forward a new analytical method in order to evaluate the stability of the process of aluminum alloy pulsed MIG welding. The ratio of the first and the second peak in arc voltage signal probability density was selected to evaluate aluminum alloy pulse MIG welding stability. By calculating the arc voltage signal probability density from 80 sets of welding experiments, the ratio of the two peaks in arc voltage probability in every set was captured. And the evaluation system of aluminum alloy pulse MIG welding stability was established. The smaller the ratio of peaks in arc voltage signal probability density is, the better the stability of the welding will be;the bigger the ratio of peaks in arc voltage signal probability density is, the poorer the stability of the welding will be.
文摘A Reynolds stress closure based on the generalized Langevin model (GLM), developed by Haworth and Pope, is applied to the flow calculation with swirl-induced recirculation. The purpose of the work is to assess the performance of this model under the complex flow conditions caused by the presence of strong swirl which gives rise to both unconventional recirculation in the vicinity of the symmetry axis and strong anisotropy in the turbulence field. Comparison of the computational results are made both with the experimental data of Roback and Johnson and the computational results obtained with the typical isotropization of production model (IPM) and the k-∈ type Boussinesq viscosity model.
文摘A kind of new method in measuring data processing called maximum entropy method(MEM) is introduced. The probability-density function (pdf) is deduced by MEM under the restraint of the square of the data. A group of experiment data is processed using the method and the result closed to the real distribution is got. The different pdf got under different order of square and by different content of samples is discussed. It draws conclusions that the pdf in the square restrain with more order than three using MEM can give the distribution of the data basically, and it is not suitable to use the square restraint of data when the samples are less.
