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Aiming at clarifying the corrosion behavior of oil casing materials in high salinity and high temperature annulus protection fluid environment, the corrosion damage sensitivity of oil casing materials under non-stressed and stressed conditions in the simulated oilfield annulus protection fluid environment was evaluated by high temperature and high pressure (HPHT) test system. The micromorphology, cross section characteristics and chemical composition of the product film on the surface of the material were analyzed and characterized by scanning electron microscope and energy dispersive spectrometer. Results showed that the corrosion of the material was relatively worse in the annulus protection liquid without deoxygenation treatment. The corrosion product film was cracked and partially detached, and the cracking of the bottom film layer could be seen at the shedding place. Moreover, the average corrosion rate of P110 material was up to 3.83 mm/a. Observing the cross section could find the cracking on the surface of the double film layer was limited to the corrosion product film, and the substate material was not involved. The material was uniformly corroded and thinned. Furthermore, after deoxygenation treatment, the erosion of the annulus protection fluid decreased significantly, and the corrosion rate of P110 material decreased by 80%. Generally, P110 and P110SS were insensitive to stress corrosion cracking under the synergistic effect of high temperature and high pressure annulus protection fluid without deoxygenation treatment environment and loading stress, and corrosion thinning was the main corrosion damage mode of P110 oil casing material.

Dynamical properties of vector localized and periodic waves hold significant importance in the study of physical systems. In this work, we investigate the matrix Hirota equation with sign-alternating nonlinearity via the binary Darboux transformation. For the two interacting components, we construct the binary Darboux transformation formulas, vector localized, and periodic wave solutions. Via those solutions, different kinds of nonlinear waves can be achieved, including rogue waves, solitons, positons, and periodic waves. When the imaginary part of the spectral parameter is not zero, eye-shaped rogue waves appear in one component, and the twisted rogue wave pairs in the other component. As the spectral parameter is real, we derive distinct forms of vector localized and periodic waves on the non-zero background, such as the vector solitons, positons, periodic waves, breathers on the periodic wave background, and rational solitons. These results may be valuable in this investigation of nonlinear waves in physical systems. [ABSTRACT FROM AUTHOR]

In this paper, we study a (3+1)-dimensional generalized shallow water wave equation with variable coefficients, which describes the flow below a pressure surface in a fluid. We give the Kadomtsev–Petviashvili hierarchy reduction and construct the multi-soliton solutions and semi-rational solutions in terms of the Gramian. For the multi-soliton solutions, we conclude that: (1) v 1 (t) affects the directions for the two solitons to move; (2) there is the periodic interaction of the two solitons when v 2 (t) is a periodic function and (3) the magnitudes of the velocities for the two solitons increase as the amplitude of the periodic function v 2 (t) increases, where v 1 (t) represents the perturbed effect, v 2 (t) indicates the dispersion effect and t is an independent variable. For the first-order semi-rational solutions, we see that: (1) the fission with v 1 (t) < 0 and fusion with v 1 (t) > 0 appear; (2) there is the periodic interaction when v 2 (t) is a periodic function; (3) the magnitude of the velocity for the soliton increases as the amplitude of the periodic function v 2 (t) increases and (4) the lump becomes narrower as the amplitude of the periodic function v 4 (t) decreases, where v 4 (t) indicates the perturbed effect. [ABSTRACT FROM AUTHOR]

Complexes of proteins are central to certain cellular processes. Investigated in this paper is the three-coupled fourth-order nonlinear Schrödinger system, which is used for describing the alpha helical proteins with interspine coupling at the fourth order. With respect to the three-component amplitudes of the molecular excitation, we derive a Lax pair and construct the corresponding Nth-order Darboux transformation, where N is a positive integer. Three types of the Nth-order rogue wave solutions are obtained with the help of the matrix analysis method. The first-order rogue waves with each component containing one, two or three rogue waves are derived. We observe that the width of the first-order vector rational rogue wave along the distance axis increases with the value of the lattice parameter increasing, while the width of the first-order vector rational rogue wave along the time axis decreases with the value of the lattice parameter increasing. We present the second-order vector rational rogue waves with each component constituted by five, seven or nine rogue waves. Vector semi-rational rogue waves display the coexistence of the rogue waves and line/Y-shaped breathers. [ABSTRACT FROM AUTHOR]

Investigation is conducted on a (3+1)-dimensional generalized Kadomtsev–Petviashvili equation in fluid mechanics and plasma physics. By virtue of the homoclinic-test, ansatz and polynomial-expansion methods, we construct the breather and lump solutions, shock wave solutions and travelling-wave solutions, respectively. We observe that the breather propagates steadily along a straight line with certain angles with the x, y and z axes. We observe that the amplitude and shape of the bright-dark lump wave keep unchanged during the propagation. We observe that the amplitude and the shape of the shock wave keep unchanged during the propagation. We graphically analyse the effects of the coefficients in the equation on the breather, lump and shock waves. We find that the lump is the most stable while the shock wave is the least stable under the same perturbation among the breather, lump and shock waves. [ABSTRACT FROM AUTHOR]

Under investigation in this paper is a (2+1)-dimensional Davey-Stewartson system, which describes the transformation of a wave-packet on water of finite depth. By virtue of the bell polynomials, bilinear form, Bäcklund transformation and Lax pair are got. One- and two-soliton solutions are obtained via the symbolic computation and Hirota method. Velocity and amplitude of the one-soliton solutions are relevant with the wave number. Graphical analysis indicates that soliton shapes keep unchanged and maintain their original directions and amplitudes during the propagation. Elastic overtaking and head-on interactions between the two solitons are described. [ABSTRACT FROM AUTHOR]