Buckling analysis of laminated composite elliptical shells using the spline finite strip procedure.

According to the first order shear deformation plate assumption, current paper numerically investigates the buckling problem of cylindrical shells with oval cross-section under simply supported boundary condition subjecting to uniform and non-uniform loads via spline finite strip method. Equilibrium governing equations are generated based upon the virtual work's principle. Shell displacement function is assumed to be as dual development of degree 3 spline functions and Lagrange polynomial functions. The analysis method used at any time with any type of loading can calculate deformation and buckling. The step-by-step critical load is calculated using the determinant of the stiffness matrix. In the present paper, it is supposed that the applied linear elastic materials consist of isotropic and non-isotropic materials. Numerical studies are performed to indicate the effects of shell geometry, materials, and layered materials on the buckling load. For the validation purpose, the results of current research are compared with those of previous researches and ABAQUS software.

Time-domain model identification based on reduced output data.

System identification based on incomplete measurements has extensively been studied in recent years. In this paper, the difference between state space models identified based on single-output and multi-output data is studied. The purpose is to investigate the relation between a typical output signal and other input-output signals in observable systems. We investigate to what extent a multidimensional system can be modeled by exploiting single-output measurements. The subspace system identification framework is utilized to compare the time-domain models identified based on a single-output and multi-output data set. It is demonstrated that by manipulating some particular row space of measured outputs, it is possible to achieve predictions of unmeasured outputs. The notion is mathematically developed and verified by several numerical and experimental tests. The idea can be generalized for every time-domain identification technique and input type, specially in dealing with incomplete measurements. The consequence is useful for reducing the number of measuring instruments in experimental test of multi-dimensional systems.