Overview and update.

A summary of points of agreement and disagreement among the preceding articles is presented. Attention is called to implicit assumptions which if openly acknowledged would improve dialogue on peer review issues. Pertinent events that have occurred since the Anaheim symposium are reviewed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On upgrading the numerics in combustion chemistry codes

A method of updating and reusing legacy FORTRAN codes for combustion simulations is presented using the DAEPACK software package. The procedure is demonstrated on two codes that come with the CHEMKIN-II package, CONP and SENKIN, for the constant-pressure batch reactor simulation. Using DAEPACK generated code, analytical derivative calculations, sparsity pattern information, and hidden discontinuity information can be obtained for the models of interest. This information can be easily integrated with different solvers giving the modeler great flexibility in selecting the best solution procedure. Using the generated code, the CONP code was connected to three different solvers, and the SENKIN code was connected to two different solvers. The effect of model formulation, analytical derivatives, sparsity, and sensitivity equation solution method were analyzed for three large kinetic mechanisms for methane, acetylene, and n-heptane. For the n-heptane model, with 544 species and 2446 reactions, a factor of 10-speed improvement over the original solution procedure was found using analytical derivatives and sparse linear algebra. For sensitivity calculations, for a small number of parameters, a factor of 55 improvement over the original solution procedure was found for the n-heptane problem. Upon closer examination of results, no one method is found to always be superior to other methods, and selection of the appropriate solution procedure requires an examination of the specific kinetic mechanism, which is easily conducted using DAEPACK generated code.     

The effects of pressure on the isothermal fluid behavior of bituminous coals

An investigation into the effects of pressure (helium gas) on the isothermal fluid behavior includes: (1) the effect of pressure on the rate of melting and coking as evidenced by the rate constants k(melt) and k(coke); (2) the effect of pressure on the energies of activation of melting and coking; (3) the effects of pressure on the characteristic times; (4) the effects of pressure on the maximum isothermal fluidity. Results from the effects of pressure on k(melt) revealed that it was generally the high total sulfur, low nitrogen, low reactives/mineral matter ratio, medium rank coals which show the greatest increase in k(melt), whereas the highest rank coals show the least decrease in k(coke). The energies of activation of melting and coking were not significantly affected by pressure. The investigation also reveals increases or decreases in the respective times of softening, maximum fluidity, resolidification and total time of fluid behavior under isothermal pressurized conditions. There appears the possibility that these shifts may be rank dependent. Additionally, the lower rank coals show the largest relative increase in their fluidities when subjected to pressure. Empirical relationships were derived in order to quantitatively predict the maximum isothermal fluidity for most (fluid) coals at a given pressure.     

Using bald eagles to indicate the health of the Great Lakes' environment

The bald eagle (Haliaeetus leucocephalus) is one of the most studied birds of North America, and a great amount of natural life‐history information, including the response of various stressors on the eagles' ability to reproduce, are well known. In Michigan, the eagle has been chosen to track the trends of bioaccumulative compounds of concern across watersheds in the state. The state has been divided into major watersheds, and 20% of these are surveyed each year. A control area in northern Minnesota, Voyageurs National Park, is also sampled annually. We report here on the methods used, the preliminary results of the 1999 field season, and how differences in mercury concentrations varied over a 10‐year period. Mercury in feathers of nestling eagles declined over time only in Lakes Michigan and Huron, but have not decreased among other subpopulations in Michigan. Concentrations of polychlorinated biphenyls (PCBs) and 4,4′‐DDE in blood plasma from nestling eagles have declined over time for most subpopulations; however, they remain greater for breeding areas associated with the Great Lakes' food web. Sea eagles of the genus Haliaeetus are a good sentinel species to track trends in bioaccumulative compounds in aquatic systems.     

Use of radial forces for fault detection in tapping

A model-based method for fault detection in tapping based on torque and radial forces is proposed. The method allows the identification of faults typical of a tapping operation including axial misalignment, tap runout, tooth breakage both singly and together. The validation experiments have been run on aluminum 356 workpieces for different combinations of process faults. Results have shown that the model predictions are in good agreement with the experimental radial force and torque signals under various fault conditions.     

Does {charm} need depth? Similarity and levels-of-processing effects in cued recall.

Eich (1985) recently presented a distributed memory model in which the pattern of results used to support the levels-of-processing view of Craik and Lockhart (1972) was modeled by different degrees of similarity between the encoding context and the to-be-recalled item. We report two experiments in which both phonemic and semantic similarity were varied between pairs of words and incidental acquisition (rhyme vs. category judgments) was varied across the same pairs of items. In both experiments the manipulation of the acquisition task produced a difference in cued-recall performance for positive and negative rhyme and category judgments. Recall was better following a category encoding decision than following a rhyme decision. This difference was independent of the effects of similarity, which demonstrated that Eich's (1985) assumptions regarding the effects of similarity are not sufficient to account for the differences resulting from the manner in which subjects encode information. An alternative method of modeling the levels-of-processing effect within the framework of distributed memory models is proposed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intrinsic Volume Changes of Self-propagating Synthesis

The final product(s) of self-propagating synthesis are shown to be intrinsically denser than the starting reactants. This behavior results in intrinsic decreases in the sample volume that increase with both the heat of reaction and the adiabatic combustion temperature. Forming of liquid product(s) during reaction simply adds another intrinsic source of porosity, i.e. changes in volume on product solidification. Thus, obtaining fully dense bodies from self-propagating synthesis requires a mechanism for reducing porosity, e.g. hot-pressing.     

A compliant-hull concept for planning craft wave-impact shock reduction

The subject of this paper is analysis of high-speed planing-craft wave impact, with the inclusion of hull-surface compliance. The analysis methods were extended in an effort to develop compliant-surface technology for wave-impact shock reduction. The practical outcome of this work, along with experimental cylinder drop-test evaluations, have been reported previously. The overall technology developed is composed of compliant plates over a sub-length of the boat hull. The plates are hinged at the boat keel and supported by vented air bags at the chines. Thus, the required analysis has coupled hydrodynamic, gas-dynamic, and structural-dynamic parts. Only the hydrodynamic part of the complete model is covered here. On the basis of the cylindrical geometry of the drop-test cylinder, two-dimensional theory has been used exclusively. The time history of the distribution of plating deflection predicted from the full analysis is imposed in the free-falling cylinder analysis to demonstrate execution of the hydrodynamic part of the complete coupled theory. The reductions in impact acceleration reported here are therefore the same as determined from the complete analysis.     

Epoxy paint failure in B-52 fuel tanks: Part II. Influence of DIEGME concentration in the fuel on the failure process

A model has been proposed to explain the failure of the original BMS10-39 epoxy paint on upper vertical surfaces in B-52 fuel tanks. The model involves interaction of the paint with DIEGME, a fuel system ice inhibitor (FSII) in jet fuel, that is distilled from the liquid fuel. In this communication, distillation experiments used to support the model are refined to better match the mass transfer of vapor from fuel in a B-52 fuel tank at close to room temperature. The interaction of these lower temperature distillates with the paint affirms the earlier model. On the basis of these experiments it is proposed that paint failure may be controlled or eliminated by reducing the level of DIEGME in the fuel. Proposed changes in military jet fuel composition are detailed.