A three-dimensional (3-D) positioning system on the basis of bat algorithm (BA) using visible light communication is proposed in this work. BA is a global optimization algorithm that can be used to solve the indoor positioning problem. In BA, the positioning process is considered to be a process of searching for the receiver by many bats in an indoor space of $3\mathrm{m}\times 3\mathrm{m}\times 4\mathrm{m}$. Therefore, taking advantage of the bat search algorithm, 3-D low-complexity and high-precision indoor positioning is able to be actualized when the number of iterations reaches a certain condition. The simulation results show that the system can achieve high-precision positioning at different signal-to-noise ratios. Meanwhile, a trajectory tracking experiment is carried out to validate the good performance of this positioning system. The proposed algorithm is a positioning method with good potential in various positioning applications.

To evaluate the settlement of saturated clay ground under the time-dependent loading, the unified hardening (UH) constitutive model considering the time effect was used to describe the elastic visco-plasticity of the soil and Hansbo's flow equation was applied to reflect non-Darcian flow. Thus, the classical Terzaghi consolidation equation was modified considering the influence of gravitational stress of the ground. The finite volume method was introduced to solve the numerical solution of the modified equation, and the corresponding program was compiled based on the above algorithm. The applicability of the present program was validated by comparing with the existing results in the literature. Then the effect of some parameters on the consolidation behaviour was investigated. The calculated results showed that the excess pore water pressure in the ground is accumulated at the initial stage of loading. Furthermore, when the viscosity of the soil is considered, the maximum excess pore water pressure in the ground away from the permeable boundary can even exceed the load imposed on the upper surface of the ground. In addition, prolonging the construction period, thickening the soil layer, increasing the secondary consolidation coefficient and the parameters of Hansbo's flow will delay the consolidation process of ground.

To further investigate the rheological consolidation mechanism of soft soil ground with vertical drains, the fractional‐derivative Merchant model (FDMM) is introduced to describe the viscoelastic behavior of saturated clay around the vertical drains, and the flow model with the non‐Newtonian index is employed to describe the non‐Darcian flow in the process of rheological consolidation. Accordingly, the governing partial differential equation of the ideal sand‐drained ground with coupled radial‐vertical flow is obtained under the assumption that the vertical strains develop freely. Then, the numerical solution to the consolidation system is conducted using the implicit finite difference method. The validity of this method is verified by comparing the results of Barron’s consolidation theory. Furthermore, the effects of the parameters of non‐Darcian flow and FDMM on the rheological consolidation of ground with vertical drains are illustrated and discussed.