Multi-band polarization switch based on magnetic fluid filled dual-core photonic crystal fiber

The research of high-performance polarization controllers is of great significance for expanding the application field of polarization optics. Here, a polarization switch is demonstrated by using a dual-core photonic crystal fiber(DCPCF)with four symmetrical air holes, placed above and below each core, filled with magnetic fluid(MF). The switch, which utilizes a magnetic field to change the coupling length ratio of the x and y polarization modes, enables dynamic tuning of the polarization state and extinction ratio. Numerical results show that when the working length is 36.638 mm, the magneto–optical polarization switch can operate in four communication bands, i.e., 1509 nm to 1520 nm, 1544 nm to1556 nm, 1578 nm to 1591 nm, and 1611 nm to 1624 nm. Moreover, the extinction ratio(ER) is greater than 20 d B in the fiber length range of 38.5 mm to 38.7 mm, indicating that the device has a good fault tolerance for the interception of the fiber length.

Investigation of the Mechanism of Grout Penetration in Intersected Fractures

To study the penetration mechanism of cement-based slurry in intersected fractures during grouting and the related pressure distribution,we have used two different variants of cement,namely,basic cement slurry and fast-setting cement slurry.The influence of a retarder,time-varying viscosity,fracture width and location of injection hole is also considered.A finite element software is used to implement two and three-dimensional numerical models for grouting of intersected fractures in hydrostatic conditions.Results show that there are significant differences in the diffusion morphology and pressure distribution depending on the considered cement slurry.Retarder can effectively slow down the rising rate of injection pressure and extend the diffusion distance of grout.The influence of the branch fracture is more important when basic cement slurry is considered,indicating that the change of grout pressure is correlated with the slurry viscosity.The faster the viscosity increases,the less evident is the effect.

Validation of a particle impact breakage model incorporating impact number effect

This paper presents validation of a particle impact breakage model i.e.Vogel and Peukert model with a focus on the impact number.The Vogel and Peukert model developed based on mechanical and sta-tistical foundation has been widely used in various fields such as mineral engineering and chemical engineering but is barely studied in the application of repeated impact.The selective breakage data in the literature is collected to provide the database for model validation.It has shown that the Vogel and Peukert model is generally applicable to all the breakage cases considering the impact number.The effect of impact number is further elaborated in the population balance model(PBM)whereas the particle dynamics are provided from Discrete Element Method(DEM)simulation of an impact pin mill.The global system analysis of impact number is carried out with the synergic effect from impact velocity.The successful validation of Vogel and Peukert model incorporating the effect of impact number demon-strates its versatility whilst other key parameters such as impact energy and particle size can be considered in parallel.