宇宙的命运与Ia型超新星（中）

宇宙膨胀的发现 1923年,俄罗斯宇宙学家亚历山大·弗里德曼首先用∧=0的爱因斯坦场方程建立了宇宙学膨胀模型（∧为宇宙学常数）,他发表论文阐述了膨胀宇宙的思想,即曲率分别为正、负、零时的三种情况,称为弗里德曼宇宙模型。     

玛湖凹陷百口泉组粗碎屑粒度特征与环境指示意义

现有粒度分析方法难以表征玛湖凹陷百口泉组粗碎屑粒度特征。在岩心观察和沉积相分析基础上,结合薄片分析,建立玛湖凹陷百口泉组粗碎屑粒度概率累积曲线,以及粗粒碎屑沉积环境的弗里德曼模式图,确定概率累积曲线和流体性质关系。结果表明,研究区粒度概率累积曲线可分为6类,分别对应碎屑水道、辫状水道、辫状分支水道、水下分流河道、河口坝和前扇三角洲沉积微相环境;随着流体性质由富砾碎屑流—颗粒流—富砂碎屑流—洪流—牵引流,粒度概率累积曲线依次出现宽缓上拱式—低斜多跳一悬式—直线式—低斜两段式—两跳一悬三段式—低斜三段式—典型两段式;随着流体由碎屑流逐渐向牵引流过渡,曲线斜率逐渐增大。该研究结果可为以粗碎屑为主的储层区块沉积环境研究提供参考。     

Analysis of radial basis function interpolation approach

The radial basis function （RBF） interpolation approach proposed by Freedman is used to solve inverse problems encountered in well-logging and other petrophysical issues. The approach is to predict petrophysical properties in the laboratory on the basis of physical rock datasets, which include the formation factor, viscosity, permeability, and molecular composition. However, this approach does not consider the effect of spatial distribution of the calibration data on the interpolation result. This study proposes a new RBF interpolation approach based on the Freedman＇s RBF interpolation approach, by which the unit basis functions are uniformly populated in the space domain. The inverse results of the two approaches are comparatively analyzed by using our datasets. We determine that although the interpolation effects of the two approaches are equivalent, the new approach is more flexible and beneficial for reducing the number of basis functions when the database is large, resulting in simplification of the interpolation function expression. However, the predicted results of the central data are not sufficiently satisfied when the data clusters are far apart.     

Redshift drift reconstruction for some cosmological models from observations

Redshift drift is a tool to directly probe the expansion history of the uni- verse. Based on the Friedmann-Robertson-Walker framework, we reconstruct the ve- locity drift and deceleration factor for several cosmological models using observa- tional H（z） data from the differential ages of galaxies and baryon acoustic oscillation peaks, luminosity distance of Type Ia supernovae, cosmic microwave background shift parameter, and baryon acoustic oscillation distance parameter. They can, for the first time, provide an objective and quantifiable measure of the redshift drift. We find that reconstructed velocity drift with different peak values and corresponding redshifts can potentially provide a method to distinguish the quality of competing dark energy mod- els at low redshifts. Better fitting between models and observational data indicate that current data are insufficient to distinguish the quality of these models. However, by comparing with the simulated velocity drift from Liske et al, we find that the Dvali- Gabadadze-Porrati model is inconsistent with the data at high redshift, which origi- nally piqued the interest of researchers in the topic of redshift drift. Considering the deceleration factor, we are able to give a stable instantaneous estimation of a transition redshift of zt ~ 0.7 from joint constraints, which incorporates a more complete set of values than the previous study that used a single data set.