Search

Due to many experimental data required and a lot of calculations involved, it is very complex and cumbersome to model prism-based liquid-refractive-index-measuring methods. We develop a new method of mathematical modelling for measuring refractive index of a liquid based upon the Fresnel formula and prism internal reflection at an incident angle less than the critical angle. With this method, only two different concentrations measurements for a kind of solution can lead to the determination of computational model. Measurements are performed to examine the validity of the theoretical model. Experimental results indicate the feasibility of the theoretical model with an error of 1%. The method is also capable of measuring even smaller changes in the optical refractive index of the material on a metal surface by the surface plasma resonance sensing techniques.

The kinetics of the non-isothermal crystallization of Zr55Cu30Al10Ni5 bulk metallic glass was studied by differential scanning calorimetry in the mode of continuous heating. It is found that both glass transition and crystallization of the amorphous alloy behave in a marked kinetic nature. The activation energy E and frequency factor k0 for crystallization were determined by the Kissinger method, which yields E = 230 kJ/mol, and k0 = 4.2×1012/s. The value of k0 is much smaller than that for conventional amorphous alloys, demonstrating that the atomic mobility in bulk metallic glasses is quite sluggish. The crystallization mechanism in the non-isothermal process was analysed in terms of the kinetic transformation equation for the solid-state phase transformation. This reveals that the crystallization kinetic function f(x) for Zr55Cu30Al10Ni5 can be described by the Johnson-Mehl-Avrami equation, i.e. f(x) = (1-x)[-ln (1-x)](n-1)/n, with n = 1.75. This indicates that the non-isothermal crystallization of Zr55Cu30Al10Ni5 bulk metallic glass is governed by diffusion-controlled one-dimensional growth. Finally, the different crystallization mechanisms in the isothermal and non-isothermal processes are discussed.

A polarization-independent all-fibre comb filter with dynamically halved channel spacing is proposed. The filter is based on high-birefringent fibre Sagnac interferometers and its channel spacing can be dynamically halved by turning on an optical switch. A good agreement between the numerical simulation and the experimental results is achieved.

We studied and compared the transport properties of charge carriers in bilayer graphene, monolayer graphene, and the conventional semiconductors (the two-dimensional electron gas (2DEG)). It is elucidated that the normal incidence transmission in the bilayer graphene is identical to that in the 2DEG but totally different from that in the monolayer graphene. However, resonant peaks appear in the non-normal incidence transmission profile for a high barrier in the bilayer graphene, which do not occur in the 2DEG. Furthermore, there are tunneling and forbidden regions in the transmission spectrum for each material, and the division of the two regions has been given in the work. The tunneling region covers a wide range of the incident energy for the two graphene systems, but only exists under specific conditions for the 2DEG. The counterparts of the transmission in the conductance profile are also given for the three materials, which may be used as high-performance devices based on the bilayer graphene.