NASTRAN nonlinear vibration analysis of beam and frame structures

A capability for the nonlinear vibration analysis of beam and frame structures suitable for use with NASTRAN level 15.5 is described. The nonlinearity considered is due to the presence of axial loads induced by longitudinal end restraints and lateral displacements that are large compared to the beam height. A brief discussion is included of the mathematical analysis and the geometrical stiffness matrix for a prismatic beam (BAR) element. Also included are a brief discussion of the equivalent linearization iterative process used to determine the nonlinear frequency, the required modifications to subroutines DBAR and XMPLBD of the NASTRAN code, and the appropriate vibration capability, four example problems are presented. Comparisons with existing experimental and analytical results show that excellent accuracy is achieved with NASTRAN in all cases

Core Product Competence and Productivity Gains: The Role of Foreign Ownership

Recent theoretical contributions provide predictions about the effects of core product competence on firms’ productivity. However, we know little about the influence of foreign ownership on core product competence that might also lead to productivity gains across firms. This paper uses firm-level data for 137 countries to investigate how foreign ownership affects firms’ decision to become specialised at core products and the subsequently firm productivity gains. To tackle the possible endogeneity of foreign ownership, the instrumental variable approach and the propensity score matching technique are employed. The results show that foreign ownership has a positive and significant effect on firms’ core product competence and this positive effect leads to produc-tivity gains, especially for the most productive firms. We further reveal that foreign competition within an industry encourages firms to become specialised at core products, which could further lead to productivity gains across firms

Foreign Direct Investment and Relative Capacity: Theory and Evidence

This paper builds a bilateral FDI-output model to study intermediary roles played by the relative differences in human capital and technology in triggering the gross-output-enhancing effect of inward foreign direct investment (FDI). Our model develops several testable hypotheses to assess how these intermediary factors—the differences between leader and follower countries' capabilities—determine the technology transfer and shorten the gross output gap between the frontier and follower countries. In our empirical work, we employ country-level panel data that contain 67 countries from 1977 to 2013 and find that the differences in human capital and technology, which take into account the gap in capacity between the leader and follower countries, are the determinants that trigger the gross-output-enhancing effect of FDI. Our results are robust to the non-linear effects, cyclical fluctuations, endogeneity of FDI per se, and the variation of the host countries' institutions and inflation

Application of heat pipes to spacecraft thermal control problems

Application of heat pipes to spacecraft thermal control problem