We explore the impact of the Sandage-Loeb （SL） test on the precision of cosmological constraints for f（T） gravity theories. The SL test is an important supplement to current cosmological observations because it me...We explore the impact of the Sandage-Loeb （SL） test on the precision of cosmological constraints for f（T） gravity theories. The SL test is an important supplement to current cosmological observations because it measures the redshift drift in the Lyman-α forest in the spectra of distant quasars, covering the ＂redshift desert＂ of 2 ≤ z ≤ 5. To avoid data inconsistency, we use the best-fit models based on current combined observational data as fiducial models to simulate 30 mock SL test data. We quantify the impact of these SL test data on parameter estimation for f（T） gravity theories. Two typical f（T） models are considered, the power-law model f（T）pL and the exponential-form model f（T）Exp. The results show that the SL test can effectively break the existing strong degeneracy between the present-day matter density Ωm and the Hubble constant Ho in other cosmological observations. For the considered f（T） models, a 30-year observation of the SL test can improve the constraint precision of Ωm and H0 enormously but cannot effectively improve the constraint precision of the model parameters.展开更多
The Coherent Point Drift (CPD) algorithm which based on Gauss Mixture Model is a robust point set registration algorithm. However, the selection of robustness weight which used to describe the noise may directly affec...The Coherent Point Drift (CPD) algorithm which based on Gauss Mixture Model is a robust point set registration algorithm. However, the selection of robustness weight which used to describe the noise may directly affect the point set registration efficiency. For resolving the problem, this paper presents a CPD registration algorithm which based on distance threshold constraint. Before the point set registration, the inaccurate template point set by resampling become the initial point set of point set matching, in order to eliminate some points that the distance to target point set is too close and too far in the inaccurate template point set, and set the weights of robustness as . In the simulation experiments, we make two group experiments: the first group is the registration of the inaccurate template point set and the accurate target point set, while the second group is the registration of the accurate template point set and the accurate target point set. The results of comparison show that our method can solve the problem of selection for the weight. And it improves the speed and precision of the original CPD registration.展开更多
基金This work was supported by the National Natural Science Foundation of China under Grant Nos. 11175042 and 11522540, the Provincial Department of Education of Liaon- ing under Grant No. L2012087, and the Fundamental Research Funds for the Central Universities under Grant Nos. N140505002, N140506002, and N140504007.
文摘We explore the impact of the Sandage-Loeb （SL） test on the precision of cosmological constraints for f（T） gravity theories. The SL test is an important supplement to current cosmological observations because it measures the redshift drift in the Lyman-α forest in the spectra of distant quasars, covering the ＂redshift desert＂ of 2 ≤ z ≤ 5. To avoid data inconsistency, we use the best-fit models based on current combined observational data as fiducial models to simulate 30 mock SL test data. We quantify the impact of these SL test data on parameter estimation for f（T） gravity theories. Two typical f（T） models are considered, the power-law model f（T）pL and the exponential-form model f（T）Exp. The results show that the SL test can effectively break the existing strong degeneracy between the present-day matter density Ωm and the Hubble constant Ho in other cosmological observations. For the considered f（T） models, a 30-year observation of the SL test can improve the constraint precision of Ωm and H0 enormously but cannot effectively improve the constraint precision of the model parameters.
文摘The Coherent Point Drift (CPD) algorithm which based on Gauss Mixture Model is a robust point set registration algorithm. However, the selection of robustness weight which used to describe the noise may directly affect the point set registration efficiency. For resolving the problem, this paper presents a CPD registration algorithm which based on distance threshold constraint. Before the point set registration, the inaccurate template point set by resampling become the initial point set of point set matching, in order to eliminate some points that the distance to target point set is too close and too far in the inaccurate template point set, and set the weights of robustness as . In the simulation experiments, we make two group experiments: the first group is the registration of the inaccurate template point set and the accurate target point set, while the second group is the registration of the accurate template point set and the accurate target point set. The results of comparison show that our method can solve the problem of selection for the weight. And it improves the speed and precision of the original CPD registration.
