In this paper, we present some efficient numerical schemes to solve a two-phase hydrodynamics coupled phase field model with moving contact line boundary conditions. The model is a nonlinear coupling system, which consists the Navier-Stokes equations with the general Navier Boundary conditions or degenerated Navier Boundary conditions, and the Allen-Cahn type phase field equations with dynamical contact line boundary condition or static contact line boundary condition. The proposed schemes are linear and unconditionally energy stable, where the energy stabilities are proved rigorously. Various numerical tests are performed to show the accuracy and efficiency thereafter.

Mesoscale eddies are ubiquitous in the world's oceans. They are rotated with a 10-100 km length scale. The relatively isolated water mass trapped with mesoscale eddies can propagate a long distance while maintaining the source thermohaline characteristics. Thus, there are significant differences in the thermohaline structures between the inside and outside eddies, which have profound effects on underwater acoustic propagation.The earliest studies on the impact of eddies on sound propagation were conducted by Vastano and Owens (1973) and Weinberg and Zabalgogeazcoa (1977) based on hydrological field data measured from a cyclonic Gulf Stream (GS) ring detected in 1967. Vastano and Owens (1973) first observed the significant acoustic field perturbation caused by the cyclonic ring in the relatively uniform acoustic environment of the Sargasso Sea and found a strong dispersion phenomenon of the ray path in the area where the sound channel depth changed with the ray computations. In the following year, Gemmill studied the eddy's effects on the convergence mode of sound propagation and revealed that the cold eddy destroys the cyclic distribution of the convergence zones and refracts the sound rays into the deep sound channel. Subsequently, the eddy effects on ray travel time, which reflects the sound arrival structure, were studied with a range-dependent model presented by Weinberg and Zabalgogeazcoa (1977). Although the above studies are valuable, the corresponding sensitivity investigations of sound propagation on the eddy property variation cannot be conducted because of the rarity of eddy field data. To address this problem, Henrick et al. (1977) established a parametric eddy model qualitatively validated by GS ring observation data. Through the model, the effects of eddy intensity, geometric size and peak rotation speed on sound transmission are studied. Due to the good performance of such a model in describing eddy sound

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This work designed a dual-wavelength 2D fiber Bragg grating (FBG) engraved on the single-mode fiber to measure the temperature and strain. The FBG is composed of two sub-gratings that are not overlapped spatially at the same location of the fiber core. Experiments showed that the temperature and strain sensitivities of this grating were separately measured to be 10.64 p.m./°C and 0.882,731 p.m./μɛ at the central wavelength of 1,548 nm, and 10.74 p.m./°C and 0.916,080 p.m./μɛ at the central wavelength of 1,550 nm. These coefficients constitute a coefficient matrix that can solve the problem of cross sensitivity between temperature and strain, which has been verified by varying central wavelengths caused by the synchronous change of temperature and strain.

In this paper, the preparation and spectral properties of large mode field double-clad (LMA) fiber two-dimensional fiber gratings are studied. Firstly, a new compact grating analysis model for writing fiber gratings with different periods in different regions of the fiber core is theoretically proposed, and the spectral characteristics of the gratings written in different regions of the fiber core are studied based on the transfer matrix method. A three-wavelength two-dimensional fiber grating with a designed wavelength interval of 1.57 nm was successfully fabricated using a 248 nm excimer laser in a large mode field double-clad fiber laser. The research results show that the spectral characteristics of the two-dimensional fiber grating can be changed flexibly by changing the masking parameters, and the structure is compact. The experimentally obtained two-dimensional fiber grating spectrum is consistent with the theoretical analysis. The research results provide a theoretical reference for the design, fabrication and application of two-dimensional fiber gratings.