Nonlinear free vibration of fixed off-shore framed structures

The dynamical behavior of fixed off-shore framed structures is studied using the Wittrick-Williams algorithm to solve the nonlinear eigenvalue problem. The effects of shear deformation and rotary inertia as well as axial static loading are considered in this study of nonlinear free vibration.

The members are assumed to be rigidly connected and the added water mass is assumed equal to the mass of the water displaced. The structural modeling is based on a two-dimensional representation of the three-dimensional tower assuming a constant dimension equal to the base length perpendicular to the plane. The distributed masses of the members in the plane of the frame are computed by summing up the structural mass, the mass of the water contained in the tube, and the mass of the water displaced. The member masses in the plane perpendicular to the frame are assumed to be lumped at the horizontal cross-brace levels.

The results of the study indicate that while the first two frequencies obtained from the nonlinear and linear eigenvalue solutions agree closely, the effect of nonlinear eigenvalue solution is significant for the higher frequencies. The results also highlight the significant effects of the axial static force in the dynamic tangent stiffness matrix in the free vibration study of the off-shore structure. Fields for further research include (i) soil-structure interaction studies for gravity off-shore structures, buried pipelines, and (ii) nuclear power plant structures.     

Part 14. Synthesis and properties of new polyketoamine polymers containing cycloalkanone moieties in the main chain

A new interesting class of polyketoamine polymers based on diarylidenecycloalkanone were synthesized by suspension polycondensation. These polymers were synthesized via polymerization of 2,5‐bis(4‐chloroacetylbenzylidene)cyclopentanone and 2,6‐bis(4‐chloroacetylbenzylidene)cyclohexanone with different aliphatic and aromatic diamines including, p‐phenylenediamine, m‐phenylenediamine, o‐phenylenediamine, 4,4′‐diaminodiphenylmethane, 4,4′‐diaminodiphenylether, 4,4′‐diaminodiphenylsulfone, hydrazine hydrate, 1,2‐diaminoethane, 1,3‐diaminopropane and 1,8‐diaminooctane. Model compounds were prepared by condensation of 2,5‐bis(4‐chloroacetylbenzylidene)cyclopentanone and/or 2,6‐bis(4‐chloroacetylbenzylidene)cyclohexanone with aniline in dry benzene, and their structure was confirmed by elemental analysis and spectroscopy. The structure of the polymers obtained was also confirmed by the same methods. Moreover, the identification of the polymers was carried out by other techniques, eg crystallinity from X‐ray spectroscopy, viscosimetry, thermogravimetric analysis; the morphological properties of selected examples were tested by scanning electron microscopy. The electrical conductivity of selected examples is about 10^?12 ohm cm^?1. The results are in accord with the structure. © 2002 Society of Chemical Industry     

Small/medium nuclear reactors for potential desalination applications : Mini review

Small/medium nuclear reactors (SMRs) are a promising alternative for powering large scale desalination plants. The modern generations of these systems manifest cost effectiveness and built-in safety features. The compatibility with geological and topological challenges is an added advantage. Moreover, funding opportunities and packages could be easily arranged for small/medium nuclear reactors (SMR). This mini review article provides the latest technical features of SMR nuclear plants with emphasis on pressurized light water reactors (PWR), boiling water reactors (BWR), heavy water reactors (HWR), gas cooled reactors (GCR), and liquid metal fast breeder reactors (LMFBR). Preliminary cost indicators for typical units were investigated as a part of joint effort to develop a cost database for these types of reactors. Security and safety features of small/medium reactors are identified and reviewed. This paper identifies and briefly discusses the various types of small/medium nuclear reactors to provide a preliminary evaluation and consideration of using this type of reactor in potential seawater desalination applications.