Location and sizing of a plant stack: Design study using CFD

The effect of the presence of a stack on the ground level concentration of emissions near the plant is to significantly decrease the concentrations (in practical cases of interest, by a factor of 5-10), while the presence of nearby plant buildings is to partly eliminate this beneficial effect due to the effect of the building wake. The author of this paper believes that the practical methods currently used for the evaluation of ground concentrations in these cases deserve some improvement. One line of development here suggested is the use of Computer Fluid Dynamics (CFD) codes. The author believes that presently available Code Packages in this field are sufficiently accurate. A number of case studies are presented in this paper, with the aim of encouraging the use of these rather simple methods of study.Moreover, a comparison of calculation results with a field test results confirms also the quantitative reliability of the calculation method here proposed.The main conclusions of this exercise could be the following:

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The use of CFD Computer Codes seems suitable for atmospheric dispersion calculations of interest to the nuclear plant designer and safety analyst; in particular, for design studies aimed at the definition of nuclear plant and stack arrangements, the result of this exercise seem to indicate that the methods here used are completely suitable for the comparison of various solutions.

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The use of CFD codes may avoid wrong decisions, like the elimination of a stack in the design of a nuclear plant; excessive and detrimental over-conservatism can also be avoided.

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When adequate guidance is provided, as this paper attempts to do (Appendix), the CFD calculation methods are rather robust and simple to perform.

     

Detection of vertical bending and torsional movements of a bridge using a coherent radar

Interferometric radar has been recently proposed as a measurement instrument for static and dynamic testing of large structures, such as bridges, towers, dams. At the state of the art, the equipment has been demonstrated able to follow the displacements of a bridge provided that vertical bending movements are predominant with respect to torsional ones. In this paper, the authors propose and experimentally test an advancement of the interferometric technique able to overcome the previous assumption and to retrieve the effective displacement of each single section of a bridge in case of both vertical bending and torsional movements.     

Fatigue crack growth in multi-pass butt-welded joints of mild steel

Fatigue crack growth rate properties obtained by testing multi-pass butt-welded joints in the through-the-thickness direction are presented along with a characterization of the mild steel base material. Edge-notched four-point-bending specimens are used to investigate R-ratio, specimen geometry and post-weld heat-treatment effects on fatigue crack growth rates. The pervasive influence of residual stresses on welded joint fatigue testing using the fracture mechanics approach is also discussed. For these multi-pass joints, conservative fatigue crack growth rates are obtained with post-weld heat-treated specimens.     

Polyphosphazene membrane separations—Review

The further growth of the success of membrane based operations in unusual areas depends on the development of new membranes with tunable properties and or capable to withstand severe thermal, chemical and mechanical environments. Poly(organophosphazene)s (POPs) may give an important contribution for the preparation of such new membranes. In this paper the applications of POP materials in ultrafiltration (UF), nanofiltration (NF), pervaporation (PV), vapor permeation (VP) and gas separation (GS) are reviewed, and some perspectives for future developments are outlined. Interesting results obtained with POP UF membranes indicate that they might be applied in the treatment of organic solvents or aggressive streams or also for the construction of membrane contactors. However, the versatile and tunable properties of POPs can be fully exploited in membranes whose transport and separation mechanisms rely on differences in solubility and mobility of the feed species to be separated (i.e., NI, PV, VP, and GS). POP based NF membranes have been used for water potabilization and the separation of organic dies fromi-PrOH. The research work carried out in industrial and academic laboratories, sponsored also by the US Department of Energy, has probably passed the turning point for the production of commercial PV and VP POP membranes for the separation of organies and or water from liquid and gaseous streams. Good results were obtained in the separation of acidic species (SO₃, H₂S, CO₂) from permanent gases with dense POP membranes. In perspective, the availability of new hybrid POP-inorganic materials makes it possible to bridge the gap between polymer and ceramic membranes, whose appealing capabilities are still to be explored. The outstanding versatile properties of POP can also be used for the fixation of catalytic centres on suitable membranes for the preparation of catalytic membrane reactors.     

Performance status and comorbidity in elderly cancer patients compared with young patients with neoplasia and elderly patients without neoplastic conditions

MARCKS, the major protein kinase C substrate in various cells and tissues, binds to calmodulin, acidic membrane phospholipids, and actin filaments, and these interactions are regulated by protein phosphorylation. We have previously analyzed MARCKS purified from bovine brain using capillary liquid chromatography/electrospray mass spectrometry and found that the protein structure differed significantly from that deduced from cDNA sequences [Taniguchi, H., Manenti, S., Suzuki, M., and Titani, K. (1994) J. Biol. Chem. 269, 18299-18302]. Moreover, the alignment of the protein from various species showed a lack of any conserved sequences in the C-terminal half of the molecule. This prompted us to reexamine the C-terminal amino-acid sequence of bovine MARCKS. The purified protein was digested with lysyl endoprotease, and the obtained C-terminal peptide was further digested with either Staphylococcus V8 protease or NTCB. The small peptides thus obtained were analyzed by liquid chromatography/electrospray/tandem mass spectrometry. This combined with gas-phase Edman sequencing allowed us to determine the C-terminal primary structure. The sequence obtained differed significantly from that reported previously, and the comparison with other species revealed the presence of a novel conserved domain in the C-terminal region of MARCKS.     

Thermodynamics of dissipative materials with entropic elasticity

Polymer solutions and melts can both dissipate mechanical energy in flow, as well as accumulate elastic energy. If the assumption is made that elastic energy can be accumulated only through a decrease of conformational entropy, the general thermodynamic theory for non-linear viscoelastic materials simplifies considerably. In particular, though no generality is lost as far as the constitutive equation for stress is concerned, the energy equation, which allows in principle a calculation of temperature distributions arising from frictional heating and heat removal, reduces to the usual form which is valid for viscous materials.