When the population, from which the samples are extracted, is not normally distributed, or if the sample size is particularly reduced, become preferable the use of not parametric statistic test. An alternative to the ...When the population, from which the samples are extracted, is not normally distributed, or if the sample size is particularly reduced, become preferable the use of not parametric statistic test. An alternative to the normal model is the permutation or randomization model. The permutation model is nonparametric because no formal assumptions are made about the population parameters of the reference distribution, i.e., the distribution to which an obtained result is compared to determine its probability when the null hypothesis is true. Typically the reference distribution is a sampling distribution for parametric tests and a permutation distribution for many nonparametric tests. Within the regression models, it is possible to use the permutation tests, considering their ownerships of optimality, especially in the multivariate context and the normal distribution of the response variables is not guaranteed. In the literature there are numerous permutation tests applicable to the estimation of the regression models. The purpose of this study is to examine different kinds of permutation tests applied to linear models, focused our attention on the specific test statistic on which they are based. In this paper we focused our attention on permutation test of the independent variables, proposed by Oja, and other methods to effect the inference in non parametric way, in a regression model. Moreover, we show the recent advances in this context and try to compare them.展开更多
In this paper , through the discrim ination of Farey sequence in the forced Brusselator withweak coupling , it is proved that there is a topological translation fro m a nonlinear differen tial system ( limit cycle)...In this paper , through the discrim ination of Farey sequence in the forced Brusselator withweak coupling , it is proved that there is a topological translation fro m a nonlinear differen tial system ( limit cycle) to the circle m ap .展开更多
The non-isothermal decomposition kinetics of LiClO4 in flow N2 atmosphere was studied. TG-DTA curves show that the decomposition proceeded through two well-defined steps below 900℃, and the mass loss was in agreement...The non-isothermal decomposition kinetics of LiClO4 in flow N2 atmosphere was studied. TG-DTA curves show that the decomposition proceeded through two well-defined steps below 900℃, and the mass loss was in agreement with the theoretical value. XRD profile demonstrates that the product of the thermal decomposition at 500℃ is LiCI. For the decomposition kinetics study, the activation energies calculated with the Friedman method were considered as the initial values for non-linear regression and were used for verifying the correctness of the fired models. The decomposition process was fitted by a two-step consecutive reaction： extended Prout-Tompkins equation[Bna, f（α） is （1-α）^nα^α] followed by a lth order reaction（F1）. The activation energies were （215.6±0.2） and （251.6±3.6） kJ/mol, respectively. The exponentials n and a for Bna reaction were （0.25±0.05） and （0.795±0.005）, respectively. The reaction types and activation energies were in agreement with those obtained from the isothermal method, but the exponentials were optimized for better firing and prediction.展开更多
Based on a comparison between the oxygen isotope records of benthic and plank tonic foraminifers from core 8KL of the South China Sea and sea-level change records derived from the Huon Peninsula, New Guinea, it is fou...Based on a comparison between the oxygen isotope records of benthic and plank tonic foraminifers from core 8KL of the South China Sea and sea-level change records derived from the Huon Peninsula, New Guinea, it is found that both records are very similar from 72 K a B.P. to the present, especially for the benthic oxygen isotope record. The linear regression shows that δ18O changes (0.9995‰ for benthic foraminifers and 1.022‰ for planktonic foraminifers) are equal to 100 m in sea-level fluctuation. After making temperature correction in the δ18O record of benthic foraminifers from 72 to 120 Ka B.P., the curve of sea-level oscillation of the South China Sea since 186 Ka B.P. has been reconstructed. The lowermost sea - level that occurred in the last glacial maximum and oxygen isotope stage 6 is approximately - 130 m.展开更多
为了提高风电机组的实时可靠性,避免维修不足及维修过剩问题,降低风场运维成本,基于监控与数据采集(supervisory control and data acquisition,SCADA)系统得出的监测数据,应用主元评价和非线性自回归(non-linear auto-regressive,NAR)...为了提高风电机组的实时可靠性,避免维修不足及维修过剩问题,降低风场运维成本,基于监控与数据采集(supervisory control and data acquisition,SCADA)系统得出的监测数据,应用主元评价和非线性自回归(non-linear auto-regressive,NAR)时间序列神经网络,通过建立评价及预测模型。通过实际数据验证模型有效性。结果表明:采用PCA-NAR的方法对风电机组的健康状况进行评估及预测有较好的效果,有助于帮助风场运营人员提前识别故障趋势并作出具体决策,以免机组遭受更为严重的故障。展开更多
Based on double pulse welding process characteristics, expert database structure and work flow are designed. Further, multiple outstanding specifications of 1.0 ram-diameter wire are obtained through a large number of...Based on double pulse welding process characteristics, expert database structure and work flow are designed. Further, multiple outstanding specifications of 1.0 ram-diameter wire are obtained through a large number of experiments. By making non-linear regression analysis on these groups of standards, the relationship between average welding current and other pulse parameters can be found out. Polynomial regression equation is set up for further realization of＂ parameter estimation function of the expert database. Finally, the preliminary developed expert database is tested. The result indicates that the unified adjusting and parameters estimation of the expert database leads to stable welding process and good weld appearance.展开更多
文摘When the population, from which the samples are extracted, is not normally distributed, or if the sample size is particularly reduced, become preferable the use of not parametric statistic test. An alternative to the normal model is the permutation or randomization model. The permutation model is nonparametric because no formal assumptions are made about the population parameters of the reference distribution, i.e., the distribution to which an obtained result is compared to determine its probability when the null hypothesis is true. Typically the reference distribution is a sampling distribution for parametric tests and a permutation distribution for many nonparametric tests. Within the regression models, it is possible to use the permutation tests, considering their ownerships of optimality, especially in the multivariate context and the normal distribution of the response variables is not guaranteed. In the literature there are numerous permutation tests applicable to the estimation of the regression models. The purpose of this study is to examine different kinds of permutation tests applied to linear models, focused our attention on the specific test statistic on which they are based. In this paper we focused our attention on permutation test of the independent variables, proposed by Oja, and other methods to effect the inference in non parametric way, in a regression model. Moreover, we show the recent advances in this context and try to compare them.
文摘In this paper , through the discrim ination of Farey sequence in the forced Brusselator withweak coupling , it is proved that there is a topological translation fro m a nonlinear differen tial system ( limit cycle) to the circle m ap .
基金Supported by the National Natural Science Foundation of China(No.20071026)
文摘The non-isothermal decomposition kinetics of LiClO4 in flow N2 atmosphere was studied. TG-DTA curves show that the decomposition proceeded through two well-defined steps below 900℃, and the mass loss was in agreement with the theoretical value. XRD profile demonstrates that the product of the thermal decomposition at 500℃ is LiCI. For the decomposition kinetics study, the activation energies calculated with the Friedman method were considered as the initial values for non-linear regression and were used for verifying the correctness of the fired models. The decomposition process was fitted by a two-step consecutive reaction： extended Prout-Tompkins equation[Bna, f（α） is （1-α）^nα^α] followed by a lth order reaction（F1）. The activation energies were （215.6±0.2） and （251.6±3.6） kJ/mol, respectively. The exponentials n and a for Bna reaction were （0.25±0.05） and （0.795±0.005）, respectively. The reaction types and activation energies were in agreement with those obtained from the isothermal method, but the exponentials were optimized for better firing and prediction.
基金Project 49206062 funded by the National Natural Science Foundation of China
文摘Based on a comparison between the oxygen isotope records of benthic and plank tonic foraminifers from core 8KL of the South China Sea and sea-level change records derived from the Huon Peninsula, New Guinea, it is found that both records are very similar from 72 K a B.P. to the present, especially for the benthic oxygen isotope record. The linear regression shows that δ18O changes (0.9995‰ for benthic foraminifers and 1.022‰ for planktonic foraminifers) are equal to 100 m in sea-level fluctuation. After making temperature correction in the δ18O record of benthic foraminifers from 72 to 120 Ka B.P., the curve of sea-level oscillation of the South China Sea since 186 Ka B.P. has been reconstructed. The lowermost sea - level that occurred in the last glacial maximum and oxygen isotope stage 6 is approximately - 130 m.
文摘为了提高风电机组的实时可靠性,避免维修不足及维修过剩问题,降低风场运维成本,基于监控与数据采集(supervisory control and data acquisition,SCADA)系统得出的监测数据,应用主元评价和非线性自回归(non-linear auto-regressive,NAR)时间序列神经网络,通过建立评价及预测模型。通过实际数据验证模型有效性。结果表明:采用PCA-NAR的方法对风电机组的健康状况进行评估及预测有较好的效果,有助于帮助风场运营人员提前识别故障趋势并作出具体决策,以免机组遭受更为严重的故障。
基金This work was supported by National Natural Science Foundation of China （No. 50875088） and Foundation h）r Distinguished Young Talents in Higher Education of Guaugdong （ No. LYM09099）.
文摘Based on double pulse welding process characteristics, expert database structure and work flow are designed. Further, multiple outstanding specifications of 1.0 ram-diameter wire are obtained through a large number of experiments. By making non-linear regression analysis on these groups of standards, the relationship between average welding current and other pulse parameters can be found out. Polynomial regression equation is set up for further realization of＂ parameter estimation function of the expert database. Finally, the preliminary developed expert database is tested. The result indicates that the unified adjusting and parameters estimation of the expert database leads to stable welding process and good weld appearance.
