当前观测表明宇宙在加速膨胀，这对标准宇宙学模型及广义相对论理论提出了挑战。一些学者诉诸于广义相对论的引力替代理论。本项目基于Brans-Dicke引力替代理论研究宇宙的加速膨胀。首先，我们将Brans-Dicke理论推广到非紧致的Kaluza-Klein额外维理论，研究膜上宇宙诱导物质的全息性质、耦合参数值及四维Brans-Dicke有效势等。其次，我们考虑从弦理论下的作用量出发，试图构建Brans-Dicke理论下的暗物质暗能量统一模型，以及研究该理论下的二重复标量场和chameleon标量场在加速宇宙学中的作用。项目研究将为理解宇宙加速本质，分析暗能量性质、发展引力替代理论以及探索新物理起到一定推动作用。

The current cosmic observations indicate that the universe is undergoing an accelerated expansion, which is inconsistent with the theory of general relativity and standard cosmology. Some researchers resort to substituted gravity theories of general relativity. We investigate the accelerating universe in the framework of Brans-Dicke theory of gravity. Firstly, we generalize the Brans-Dicke theory to non-compact five-dimensional Kaluza-Klein theory, with studying the holographic character of reduced matter on the brane, the value of coupling parameter, and the four-dimensional Brans-Dicke potential, etc. Secondly, considering applying the actions of string theory to Brans-Dicke theory we try to construct the unified model of dark matter and dark energy, and investigate the functions of double complex scalar field and chameleon scalar field in the Brans-Dicke theory for interpreting the accelerating universe. These studies play a boosting role on understanding the nature of accelerating universe, analyzing the characters of dark energy, developing the substituted gravity theories, and exploring the new physics.