Advanced Materials Research Vols. 671-674

Abstract: The oil well structure is comprised of stratum, concrete sheath and the steel casing. In petroleum engineering, the liquid concrete is usually poured into the annular gap between the well bore and the steel casing to form a concrete sheath. During the solidification process of the concrete, its volume and mechanical parameters may vary with time and the chemical solidification stresses will therefore be generated. At the same time, the concrete sheath is under the loading of the ground stresses and the hydraulic pressure of the drilling fluid in the casing. Nowadays, most of the researchers calculate the stresses distribution of the oil well concrete sheath based on the external loading only and the solidification process is ignored. In this work, an interference fitting algorithm in consideration of the concrete solidification process is proposed and the external loads such as ground stresses and drilling fluid hydraulic pressure in the steel casing are also considered. The calculated results show that the stresses of the concrete sheath are mainly dependent upon the hydraulic pressure of the liquid concrete and the chemical solidification stresses, rather than the external loads. In addition, an experimental facility used to simulate the oil well structure under the ground stresses is designed in this work, and the results of the experiment verified the conclusion mentioned above.

Abstract: The vortex structure of lid-driven flow in a cuboid cavity with one or a pair of moving lids is numerated using the differential quadrature method (DQM). According to the characteristics of cavity driven flow, the dimensionless governing equations and its boundary conditions used to describe the flow are established. Based on a non-staggered grid technology, the polynomial-based DQM is combined with the SIMPLE strategy to solve three-dimensional (3D) cavity driven flow. The suitable boundary condition for pressure correction equation on a non-staggered system is implemented and the continuity equation on the boundary is enforced to be satisfied. The 3D vortex structure distributions in a cuboid cavity are obtained for different Reynolds numbers and different driving modes. The analysis shows that the DQM is very suitable for the simulation of 3D vortex structure in a cavity.

Abstract: In order to get the lateral buckling performance of rectangular cantilever plate under concentrated load.200 buckling mode of 30 plates is competed by ANSYS finite element software. All kinds of buckling load and span-height ratio curves is built up with different thickness of plate. Comparison analytical solution and ANSYS solution, the length-width ratio range is concluded applicable for that formula. Then the formula is modified to make its calculated results better tally with the ones of ANSYS analyses and make precise the calculation of the critical load of lateral buckling of the plate. The solution set up foundation for rectangular cantilever plate component design and stability analysis.

Abstract: This study is focus on investigating the lateral buckling of the rectangular plate with two opposite edges clamped under the action of concentrated load. A analytical method of thirty rectangular plate which fixed at two opposite edges with one hundred and fifty buckling modality of concentrated load has been calculated by using the ANSYS finite element software. The curves of lateral buckling minimum critical load could be achieved by the calculation. Compared with the results from the existing calculation formula, the limitation applicability of the formula would be determined. To have a better agreement with ANSYS analysis results, this formula would be corrected by the analysis of the comparison between existing formula and ANSYS results. This research could provide effective methods for engineering design.

Abstract: Though it had been employed for limit analysis and integral safety assessment of pressure pipe and vessel, most of the elastic modulus adjustment procedures were applicable to simple structures because their load multiplier was mainly determined by stress. In this paper, a series of element bearing ratio (EBR) based load multiplier algorithms are given, in which the influence of both stress and material on limit load are included. The EBR based load multiplier algorithms are investigated, and two efficient algorithms are suggested. Then the two algorithms combined with the elastic modulus adjustment procedure of elastic modulus reduction method are applied to limit analysis and integral safety assessment of penstocks.

Abstract: Stability of implicit midpoint algorithm applied to solving the equation of motion with nonlinear damping. The analytical and numerical study exhibit the unconditional stability of implicit midpoint scheme for nonlinear damping systems. The work of the present paper provides theoretic base for further application of this implicit midpoint approach.

Abstract: This paper is devoted to so-called indirect discrete-continual boundary element method of structural analysis. Operational formulation of the problem is given. Using fundamental operational relations of indirect approach after construction of corresponding fundamental matrix-function in a special form convenient for problems of structural mechanics and its application resolving set of differential equations with operational coefficients is obtained. The discrete-continual design model for structures with constant physical and geometrical parameters in one direction is offered on the basis of so-called discrete-continual boundary elements. Basic pseudodifferential operators are approximated discretely by Fourier series. Fourier transformations and Wavelet analysis can be applied as well.

Abstract: The point orbits under continuous self-maps on completely densely ordered linear ordered topological spaces (CDOLOTSs) are discussed. First, we point that the density of orbits implies the topological transitivity of the continuous self-map. Then, we give the necessary conditions for the density of the orbit under the even iterations. Such conditions are established on the fact that x(x is in L, L is a closed interval on a CDOLOTS) has a dense orbit under the continuous self-map.

Abstract: Many different dust control measures have been used to reduce or control the generation of dust during mining operations. As respirable dust control is affected by the overall airflow pattern, a CFD model of the face area could be created to estimate the impact of these factors on airflow in the face area. a steady state CFD model of the airflow developed in the paper with typical field configuration of the line curtain, including leakage along the roof and floor, and with the scrubber idle. This should provide insight for further possible steps for improving dust control.

Abstract: We establish a fixed point theorem in the generalized metric space introduced by M.oradi and Beiranvand for mapping satisfying a general contractive inequality. The obtained result can be considered as an extension of the theorem of Moradi and Beiranvand.