In this paper, we not only construct the confidence region for parameters in a mixed integer-valued autoregressive process using the empirical likelihood method, but also establish the empirical log-likelihood ratio s...In this paper, we not only construct the confidence region for parameters in a mixed integer-valued autoregressive process using the empirical likelihood method, but also establish the empirical log-likelihood ratio statistic and obtain its limiting distribution. And then, via simulation studies we give coverage probabilities for the parameters of interest. The results show that the empirical likelihood method performs very well.展开更多
In this paper, the estimation of parameters based on a progressively type-I interval censored sample from a Rayleigh distribution is studied. Different methods of estimation are discussed. They include mid-point appro...In this paper, the estimation of parameters based on a progressively type-I interval censored sample from a Rayleigh distribution is studied. Different methods of estimation are discussed. They include mid-point approximation estima- tor, the maximum likelihood estimator, moment estimator, Bayes estimator, sampling adjustment moment estimator, sampling adjustment maximum likelihood estimator and estimator based on percentile. The estimation procedures are discussed in details and compared via Monte Carlo simulations in terms of their biases.展开更多
By using transport and magnetic measurement,the upper critical field H_(c2)(T)and the irreversibility line Hirr(T)has been determined.A big separation between H_(c2)(0)and Hirr(0)has been found showing the existence o...By using transport and magnetic measurement,the upper critical field H_(c2)(T)and the irreversibility line Hirr(T)has been determined.A big separation between H_(c2)(0)and Hirr(0)has been found showing the existence of a quantum vortex liquid state induced by quantum fluctuation of vortices in the new superconductor MgB_(2).Further investigation on the magnetic relaxation shows that both the quantum tunneling and the thermally activated flux creep depends weakly on temperature.However,when the melting field Hirr is approached,a drastic rise of the relaxation rate is observed.This may indicate that the melting of the vortex matter at a finite temperature is also induced by the quantum fluctuation of vortices.展开更多
Sulphur intercalated graphite composites with diamagnetic transitions at 6.7 and 37K are prepared. The magnetization hysteresis loops (MHL), x-ray diffraction (XRD) patterns, and resistance have been measured. From th...Sulphur intercalated graphite composites with diamagnetic transitions at 6.7 and 37K are prepared. The magnetization hysteresis loops (MHL), x-ray diffraction (XRD) patterns, and resistance have been measured. From the MHL, a slight superconducting-like penetration process is observed at 15K in the low field region. The XRD shows no large difference from the mixture of graphite and sulphur indicating that the volume of the superconducting phase (if any) is very small. The temperature dependence of resistance shows a typical semi-conducting behaviour with a saturation in the low-temperature region. This saturation is either induced by the delocalization of conducting electrons or by possible superconductivity in this system.展开更多
Resistive transitions of the new superconductor MgB_(2) are carried out under magnetic fields from 0 to 8 T.It is found that the irreversibility field Hirr(T)and the upper critical field Hc2(T)obtained are very close ...Resistive transitions of the new superconductor MgB_(2) are carried out under magnetic fields from 0 to 8 T.It is found that the irreversibility field Hirr(T)and the upper critical field Hc2(T)obtained are very close to those determined in the magnetic measurement.By using the Arrhenius activation lawρ=ρ0exp(-U/kBT),the activation barrier U has been determined by the low dissipation part of R(T)curves.It is found that U■kBT manifests a very weak thermal activation and thermal fluctuation effect.This may further indicate that the flux dynamics near Hirr(T)is induced by strong quantum fluctuation and tunneling of vortices.展开更多
In this paper, the estimation of parameters based on a progressively typeI interval censored sample from a Pareto distribution is studied. Different methods of estimation are discussed, which include mid-point approxi...In this paper, the estimation of parameters based on a progressively typeI interval censored sample from a Pareto distribution is studied. Different methods of estimation are discussed, which include mid-point approximation estimator, the maximum likelihood estimator and moment estimator. The estimation procedures are discussed in details and compared via Monte Carlo simulations in terms of their biases.展开更多
基金Supported by National Natural Science Foundation of China(11731015,11571051,J1310022,11501241)Natural Science Foundation of Jilin Province(20150520053JH,20170101057JC,20180101216JC)+2 种基金Program for Changbaishan Scholars of Jilin Province(2015010)Science and Technology Program of Jilin Educational Department during the "13th Five-Year" Plan Period(2016-399)Science and Technology Research Program of Education Department in Jilin Province for the 13th Five-Year Plan(2016213)
文摘In this paper, we not only construct the confidence region for parameters in a mixed integer-valued autoregressive process using the empirical likelihood method, but also establish the empirical log-likelihood ratio statistic and obtain its limiting distribution. And then, via simulation studies we give coverage probabilities for the parameters of interest. The results show that the empirical likelihood method performs very well.
基金The NSF(11271155,11001105,11071126,10926156,11071269)of Chinathe Specialized Research Fund(20110061110003,20090061120037)for the Doctoral Program of Higher Education+1 种基金the Scientific Research Fund(201100011,200903278)of Jilin Universitythe NSF(20101596,20130101066JC)of Jilin Province
文摘In this paper, the estimation of parameters based on a progressively type-I interval censored sample from a Rayleigh distribution is studied. Different methods of estimation are discussed. They include mid-point approximation estima- tor, the maximum likelihood estimator, moment estimator, Bayes estimator, sampling adjustment moment estimator, sampling adjustment maximum likelihood estimator and estimator based on percentile. The estimation procedures are discussed in details and compared via Monte Carlo simulations in terms of their biases.
基金Supported by the National Natural Science Foundation of China under Grant No.19825111the Ministry of Science and Technology of China(NKBRSF-G1999064602).
文摘By using transport and magnetic measurement,the upper critical field H_(c2)(T)and the irreversibility line Hirr(T)has been determined.A big separation between H_(c2)(0)and Hirr(0)has been found showing the existence of a quantum vortex liquid state induced by quantum fluctuation of vortices in the new superconductor MgB_(2).Further investigation on the magnetic relaxation shows that both the quantum tunneling and the thermally activated flux creep depends weakly on temperature.However,when the melting field Hirr is approached,a drastic rise of the relaxation rate is observed.This may indicate that the melting of the vortex matter at a finite temperature is also induced by the quantum fluctuation of vortices.
基金Supported by the National Natural Science Foundation of China under Grant No.19825111the Ministry of Science and Technology of China(NKBRSF-G19990646).
文摘Sulphur intercalated graphite composites with diamagnetic transitions at 6.7 and 37K are prepared. The magnetization hysteresis loops (MHL), x-ray diffraction (XRD) patterns, and resistance have been measured. From the MHL, a slight superconducting-like penetration process is observed at 15K in the low field region. The XRD shows no large difference from the mixture of graphite and sulphur indicating that the volume of the superconducting phase (if any) is very small. The temperature dependence of resistance shows a typical semi-conducting behaviour with a saturation in the low-temperature region. This saturation is either induced by the delocalization of conducting electrons or by possible superconductivity in this system.
基金Supported by the Ministry of Science and Technology of China(NKBRSF-G19990646)the National Natural Science Foundation of China under Grant No.19825111.
文摘Resistive transitions of the new superconductor MgB_(2) are carried out under magnetic fields from 0 to 8 T.It is found that the irreversibility field Hirr(T)and the upper critical field Hc2(T)obtained are very close to those determined in the magnetic measurement.By using the Arrhenius activation lawρ=ρ0exp(-U/kBT),the activation barrier U has been determined by the low dissipation part of R(T)curves.It is found that U■kBT manifests a very weak thermal activation and thermal fluctuation effect.This may further indicate that the flux dynamics near Hirr(T)is induced by strong quantum fluctuation and tunneling of vortices.
基金The NSF (11271155,11001105,11071126,10926156 and 11071269) of Chinathe Specialized Research Fund (20110061110003 and 20090061120037) for the Doctoral Program of Higher Education+1 种基金the General Humanities and Social Science Research Projects (11YJAZH125) Sponsored by Ministry of Educationthe Science and Technology Development Program (201201082) of Jilin Province
文摘In this paper, the estimation of parameters based on a progressively typeI interval censored sample from a Pareto distribution is studied. Different methods of estimation are discussed, which include mid-point approximation estimator, the maximum likelihood estimator and moment estimator. The estimation procedures are discussed in details and compared via Monte Carlo simulations in terms of their biases.
