In the Da Hinggan Mountains,the safe and smooth operation of shallowly buried oil pipelines is threatened greatly by the frozeneheave damage derived from frozen soil.At present,a closed frozeneheave simulation test is...In the Da Hinggan Mountains,the safe and smooth operation of shallowly buried oil pipelines is threatened greatly by the frozeneheave damage derived from frozen soil.At present,a closed frozeneheave simulation test is often carried out in China,with water content and dry density of samples being assumed to be constant.However,an open frozeneheave test,all the factors of which change as the test goes on,can reflect the real frozeneheave damage more accurately.In this paper,the open frozeneheave test was carried out on five types frozen soil along the ChinaeRussia Crude Oil Pipeline to measure the frozeneheave factor and water content of each soil sample and accordingly analyze their relationship.Besides,its test results were compared with that of the closed frozeneheave test.Then,the normal frozeneheave force was measured by using the displacement limiting method,and this measurement was compared with the result of the static equilibrium test.Finally,a difference significance test was conducted.It is shown that the frozeneheave factor of the open test is higher than that of the closed test;the frozeneheave factor of fine grained soil has a significant effect on the frozeneheave factor of soils,and the frozeneheave factor increases as the capillary effect or the swabbing action of soil increases;the frozeneheave factor of coarse grained soil is mainly dependent on the mud content,and it is lower than that of fine grained soil;the value of frozeneheave force is in close relation with the test methods and the sample height;it is indicated that the open frozeneheave test is more applicable to the investigation on the frozeneheave of the foundation soils of pipelines in the Da Hinggan Mountains.It is concluded that the soils for the cushion and digging/packing layers of the pipelines in the permafrost regions shall be acted by the gravel or detritus with lower mud content,and waterproof and draining pipeline jetty shall be made from the clay soils with a higher plasticity.展开更多
The West Development Policy being implemented in China is causing significant land use and land cover （LULC） changes in West China. With the up-to-date satellite database of the Global Land Cover Characteristics Dat...The West Development Policy being implemented in China is causing significant land use and land cover （LULC） changes in West China. With the up-to-date satellite database of the Global Land Cover Characteristics Database （GLCCD） that characterizes the lower boundary conditions, the regional climate model RIEMS-TEA is used to simulate possible impacts of the significant LULC variation. The model was run for five continuous three-month periods from 1 June to 1 September of 1993, 1994, 1995, 1996, and 1997, and the results of the five groups are examined by means of a student t-test to identify the statistical significance of regional climate variation. The main results are： （1） The regional climate is affected by the LULC variation because the equilibrium of water and heat transfer in the air-vegetation interface is changed. （2） The integrated impact of the LULC variation on regional climate is not only limited to West China where the LULC varies, but also to some areas in the model domain where the LULC does not vary at all. （3） The East Asian monsoon system and its vertical structure are adjusted by the large scale LULC variation in western China, where the consequences are the enhancement of the westward water vapor transfer from the east oast and the relevant increase of wet-hydrostatic energy in the middle-upper atmospheric layers. （4） The ecological engineering in West China affects significantly the regional climate in Northwest China, North China and the middle-lower reaches of the Yangtze River; there are obvious effects in South, Northeast, and Southwest China, but minor effects in Tibet.展开更多
A maximum test in lieu of forcing a choice between the two dependent samples t-test and Wilcoxon signed-ranks test is proposed. The maximum test, which requires a new table of critical values, maintains nominal α whi...A maximum test in lieu of forcing a choice between the two dependent samples t-test and Wilcoxon signed-ranks test is proposed. The maximum test, which requires a new table of critical values, maintains nominal α while guaranteeing the maximum power of the two constituent tests. Critical values, obtained via Monte Carlo methods, are uniformly smaller than the Bonferroni-Dunn adjustment, giving it power superiority when testing for treatment alternatives of shift in location parameter when data are sampled from non-normal distributions.展开更多
Detecting differential expression of genes in genom research(e.g.,2019-nCoV)is not uncommon,due to the cost only small sample is employed to estimate a large number of variances(or their inverse)of variables simultane...Detecting differential expression of genes in genom research(e.g.,2019-nCoV)is not uncommon,due to the cost only small sample is employed to estimate a large number of variances(or their inverse)of variables simultaneously.However,the commonly used approaches perform unreliable.Borrowing information across different variables or priori information of variables,shrinkage estimation approaches are proposed and some optimal shrinkage estimators are obtained in the sense of asymptotic.In this paper,we focus on the setting of small sample and a likelihood-unbiased estimator for power of variances is given under the assumption that the variances are chi-squared distribution.Simulation reports show that the likelihood-unbiased estimators for variances and their inverse perform very well.In addition,application comparison and real data analysis indicate that the proposed estimator also works well.展开更多
In this paper, we consider the general linear hypothesis testing (GLHT) problem in heteroscedastic one-way MANOVA. The well-known Wald-type test statistic is used. Its null distribution is approximated by a Hotelling ...In this paper, we consider the general linear hypothesis testing (GLHT) problem in heteroscedastic one-way MANOVA. The well-known Wald-type test statistic is used. Its null distribution is approximated by a Hotelling T2 distribution with one parameter estimated from the data, resulting in the so-called approximate Hotelling T2 (AHT) test. The AHT test is shown to be invariant under affine transformation, different choices of the contrast matrix specifying the same hypothesis, and different labeling schemes of the mean vectors. The AHT test can be simply conducted using the usual F-distribution. Simulation studies and real data applications show that the AHT test substantially outperforms the test of [1] and is comparable to the parametric bootstrap (PB) test of [2] for the multivariate k-sample Behrens-Fisher problem which is a special case of the GLHT problem in heteroscedastic one-way MANOVA.展开更多
Objective： To take advantage of Epi Info to manage and analyze disease data. Methods： After selecting the living examples for independent sample T-Test, Epi Info 5.00, 5.01a（Chinese）, 6.00, 6.04 b, 6.04 d, 2000, 2...Objective： To take advantage of Epi Info to manage and analyze disease data. Methods： After selecting the living examples for independent sample T-Test, Epi Info 5.00, 5.01a（Chinese）, 6.00, 6.04 b, 6.04 d, 2000, 2002（Chinese）were used to do the independent sample T-Test on the two living examples. Then, Intercooled StataT, Microsoft Excel（2002） and SPSS 10.0 for Windows were used to verify the results. Results： The statistical results from the Epi Info 5.00, 5.01a（Chinese） and 6.00 were the same while that from Epi Info 6.04 b, 6.04 d, 2000,2002 （Chinese）, Intercooled StataT, Microsoft Excel（2002） and SPSS 10.0 for Windows were identical In independent sample T-Test,. But the former result is different with the latter. Conclusion： There was an error in the result of T-Test from Epi Info 6.00 and former versions. Thus, it＇s important to be alert to select the versions of Epi Info to manage and analyze disease data. On the other hand, it＇s also quite pivotal to distinguish the adopted Epi Info versions when referring to the articles ane use the statistical results.展开更多
基金Project supported by the National Natural Science Foundation Project“Research on the Frozeneheave Mechanism of Marsh Turfy Soil in Seasonally Frozen Area”(No.41502272)Seed Fund Project of Changchun Institute of Technology,“Research on the FrozeneThaw Cycle Effect of Shallowly Buried Pipelines in the Permafrost Zone of Da Hinggan Mountains”(No.320160017).
文摘In the Da Hinggan Mountains,the safe and smooth operation of shallowly buried oil pipelines is threatened greatly by the frozeneheave damage derived from frozen soil.At present,a closed frozeneheave simulation test is often carried out in China,with water content and dry density of samples being assumed to be constant.However,an open frozeneheave test,all the factors of which change as the test goes on,can reflect the real frozeneheave damage more accurately.In this paper,the open frozeneheave test was carried out on five types frozen soil along the ChinaeRussia Crude Oil Pipeline to measure the frozeneheave factor and water content of each soil sample and accordingly analyze their relationship.Besides,its test results were compared with that of the closed frozeneheave test.Then,the normal frozeneheave force was measured by using the displacement limiting method,and this measurement was compared with the result of the static equilibrium test.Finally,a difference significance test was conducted.It is shown that the frozeneheave factor of the open test is higher than that of the closed test;the frozeneheave factor of fine grained soil has a significant effect on the frozeneheave factor of soils,and the frozeneheave factor increases as the capillary effect or the swabbing action of soil increases;the frozeneheave factor of coarse grained soil is mainly dependent on the mud content,and it is lower than that of fine grained soil;the value of frozeneheave force is in close relation with the test methods and the sample height;it is indicated that the open frozeneheave test is more applicable to the investigation on the frozeneheave of the foundation soils of pipelines in the Da Hinggan Mountains.It is concluded that the soils for the cushion and digging/packing layers of the pipelines in the permafrost regions shall be acted by the gravel or detritus with lower mud content,and waterproof and draining pipeline jetty shall be made from the clay soils with a higher plasticity.
文摘The West Development Policy being implemented in China is causing significant land use and land cover （LULC） changes in West China. With the up-to-date satellite database of the Global Land Cover Characteristics Database （GLCCD） that characterizes the lower boundary conditions, the regional climate model RIEMS-TEA is used to simulate possible impacts of the significant LULC variation. The model was run for five continuous three-month periods from 1 June to 1 September of 1993, 1994, 1995, 1996, and 1997, and the results of the five groups are examined by means of a student t-test to identify the statistical significance of regional climate variation. The main results are： （1） The regional climate is affected by the LULC variation because the equilibrium of water and heat transfer in the air-vegetation interface is changed. （2） The integrated impact of the LULC variation on regional climate is not only limited to West China where the LULC varies, but also to some areas in the model domain where the LULC does not vary at all. （3） The East Asian monsoon system and its vertical structure are adjusted by the large scale LULC variation in western China, where the consequences are the enhancement of the westward water vapor transfer from the east oast and the relevant increase of wet-hydrostatic energy in the middle-upper atmospheric layers. （4） The ecological engineering in West China affects significantly the regional climate in Northwest China, North China and the middle-lower reaches of the Yangtze River; there are obvious effects in South, Northeast, and Southwest China, but minor effects in Tibet.
文摘A maximum test in lieu of forcing a choice between the two dependent samples t-test and Wilcoxon signed-ranks test is proposed. The maximum test, which requires a new table of critical values, maintains nominal α while guaranteeing the maximum power of the two constituent tests. Critical values, obtained via Monte Carlo methods, are uniformly smaller than the Bonferroni-Dunn adjustment, giving it power superiority when testing for treatment alternatives of shift in location parameter when data are sampled from non-normal distributions.
基金Supported by the National Natural Science Foundation of China(11971433)First Class Discipline of Zhejiang-A(Zhejiang Gongshang University-Statistics)Hunan Soft Science Research Project(2012ZK3064)
文摘Detecting differential expression of genes in genom research(e.g.,2019-nCoV)is not uncommon,due to the cost only small sample is employed to estimate a large number of variances(or their inverse)of variables simultaneously.However,the commonly used approaches perform unreliable.Borrowing information across different variables or priori information of variables,shrinkage estimation approaches are proposed and some optimal shrinkage estimators are obtained in the sense of asymptotic.In this paper,we focus on the setting of small sample and a likelihood-unbiased estimator for power of variances is given under the assumption that the variances are chi-squared distribution.Simulation reports show that the likelihood-unbiased estimators for variances and their inverse perform very well.In addition,application comparison and real data analysis indicate that the proposed estimator also works well.
文摘In this paper, we consider the general linear hypothesis testing (GLHT) problem in heteroscedastic one-way MANOVA. The well-known Wald-type test statistic is used. Its null distribution is approximated by a Hotelling T2 distribution with one parameter estimated from the data, resulting in the so-called approximate Hotelling T2 (AHT) test. The AHT test is shown to be invariant under affine transformation, different choices of the contrast matrix specifying the same hypothesis, and different labeling schemes of the mean vectors. The AHT test can be simply conducted using the usual F-distribution. Simulation studies and real data applications show that the AHT test substantially outperforms the test of [1] and is comparable to the parametric bootstrap (PB) test of [2] for the multivariate k-sample Behrens-Fisher problem which is a special case of the GLHT problem in heteroscedastic one-way MANOVA.
文摘Objective： To take advantage of Epi Info to manage and analyze disease data. Methods： After selecting the living examples for independent sample T-Test, Epi Info 5.00, 5.01a（Chinese）, 6.00, 6.04 b, 6.04 d, 2000, 2002（Chinese）were used to do the independent sample T-Test on the two living examples. Then, Intercooled StataT, Microsoft Excel（2002） and SPSS 10.0 for Windows were used to verify the results. Results： The statistical results from the Epi Info 5.00, 5.01a（Chinese） and 6.00 were the same while that from Epi Info 6.04 b, 6.04 d, 2000,2002 （Chinese）, Intercooled StataT, Microsoft Excel（2002） and SPSS 10.0 for Windows were identical In independent sample T-Test,. But the former result is different with the latter. Conclusion： There was an error in the result of T-Test from Epi Info 6.00 and former versions. Thus, it＇s important to be alert to select the versions of Epi Info to manage and analyze disease data. On the other hand, it＇s also quite pivotal to distinguish the adopted Epi Info versions when referring to the articles ane use the statistical results.
