Nonlinear dynamic analysis of piping system using the PSEUDO force method

The nonlinearities induced by piping constraints are taken into account as generalized pseudo forces on the right-hand side of the governing hydamic equilibrium equations. Then an existing linear elastic finite element piping code, IPIPE, was modified to permit application of the procedure. This option was inserted such that the analyses could be performed using either the direct integration method or via a modal superposition method, the Newmark-Beta integration procedure being employed in both methods. The modified code was proof tested against several problems taken from the literature or developed with the nonlinear dynamics code OSCIL. The problems included a simple pipe loop, cantilever beam, and lumped mass system subjected to pulsed and periodic forcing functions. The problems were selected to gage the overall accuracy of the method and to insure that it properly predicted the jump phenomena accociated with nonlinear systems. Implementation of the method was found to be straightforward with the simplest iteration procedure for the psuedo force vector sufficing. The results predicted with the method agreed in all important aspects with existing solutions as well as those generated with other methods. As with linear analyses, the modal superposition solution mode was found to be the most efficient, however, exhibiting slightly greater inaccuracies

Development of solutions to benchmark piping problems

Benchmark problems and their solutions are presented. The problems consist in calculating the static and dynamic response of selected piping structures subjected to a variety of loading conditions. The structures range from simple pipe geometries to a representative full scale primary nuclear piping system, which includes the various components and their supports. These structures are assumed to behave in a linear elastic fashion only, i.e., they experience small deformations and small displacements with no existing gaps, and remain elastic through their entire response. The solutions were obtained by using the program EPIPE, which is a modification of the widely available program SAP IV. A brief outline of the theoretical background of this program and its verification is also included

Selective production of human antigen specific helper factor from normal volunteers: implications for human Ir genes.

Based on previous systems for generating helper cells and factors from mouse spleen cell cultures, an in vitro system for the production and detection of human helper factors to the synthetic polypeptide antigens (T,G)-A--L and GAT10 was developed. The factors are made by human peripheral blood leucocytes and are antigen-specific, as judged both by functional criteria and specific binding and elution from antigen columns. Out of the first six volunteers studied two were high responders to (T,G)-A--L, but non-responders to GAT, two responders to GAT but not (T,G)-A--L. One subject made factors to both antigens and the sixth reacted to neither. The antigens chosen are known to be under MHC-linked immune response (Ir) gene control in all animal species tested, with some strains being responders while others are not. The selective responsiveness, different between individuals, thus suggests that the response to these antigens in man is under Ir gene control. Because of the small size of the sample initially studied and HLA typed, it was not surprising that there was no clear-cut association of response with any particular histocompatibility type at the HLA-A, B, C or D locus

Organizing the circus : the engineering of miracles

This paper defines the circus as an institutionalised questioning of forms of stability and classification, and then enquires as to how such effects are produced. I begin with the cultural representations of the circus, and then move through sections on community, movement and economic organization. This order is intended to illustrate that the production of mystery is a complex affair, and that cultural and economic descriptions of this particular form of organization are necessarily entangled. Focussing on one at the expense of the other leads to either a culturalism which lacks an understanding of production, or a business model which is incapable of understanding miracles