A numerical flow simulation based on the rate form of the equation of state

A finite-difference numerical method of solution for the unsteady, incompressible Navier-Stokes equations using primitive variables is presented. The rate form of the equation of state is used for the calculation of pressure. This form of the equation of state is well-suited for use with the unsteady form of the conservation equations (mass, momentum and energy). An implicit algorithm is used for the time integration for greater numerical stability. This method is used to solve a known benchmark problem in steady-state natural convection as a test of steady-state accuracy. The results of the simulation are compared to the benchmark.     

HihO: accelerating artificial intelligence interpretability for medical imaging in IoT applications using hierarchical occlusion

Neural Computing and Applications - In the medical imaging domain, nonlinear warping has enabled pixel-by-pixel mapping of one image dataset to a reference dataset. This co-registration of data...     

Measurements and analysis of transmitted spectra from LOTUS fission-suppressed hybrid blanket driven by D-T neutrons

The neutron spectra transmitted across a fission-suppressed hybrid blanket and its components, driven by a low intensity 14 MeV Haefely neutron generator, were measured with a 2×2 NE213 detector at LOTUS facility. These experiments have been analyzed with 2D and 3D codes DOT3.5 and MCNP, respectively. The spectral integrals between 15 to 1 MeV show good agreement among the 2D, the 3D, and the NE213 for 15 cm lead, 18 cm beryllium, and 25 cm graphite slabs. However, there are large discrepancies for 6.2 cm stainless steel and 15 cm lithium carbonate slabs. The assemblies involving two or more of these slabs reflect these tendencies. We observe also considerable disagreement over pointwise spectra for a number of assemblies.Work done while on visiting assignment to Institut de Génie Atomique, E.P.F.L.     

An information-theoretic approach to the written transmission of old English

Information theory offers a means for analyzing some constraints on the reading and copying process in Old English. Entropy for strings of various lengths offers a baseline measure of the uncertainty involved in transmission of Old English texts, while avoiding the pitfalls of applying models of modern reading to early medieval practice. Analysis of lengthy prose and verse texts in Old English revealed uniformly high values for entropy at all string lengths. High entropies may be the result of the language's irregular orthography, poetic koiné, and several dialects and imply that the language may have been easy to write but difficult to read. The low redundancy of the language which its high entropy values indicate suggests that the reader of Old English played an enhanced role in decoding a text and may provide an explanation for the high variability in the transmission of Old English verse.Katherine O'Brien O 'Keeffe is Professor of English at Texas A&M University and a co-director of its Interdisciplinary Group for Historical Literary Study.William Rundell is Professor of Mathematics at Texas A&M University.     

Surface mass transport of alumina

The kinetics of thermal grooving at the intersection of rhombohedral twin boundaries with the \((10\bar 10)\) plane in aluminium oxide were measured from 1773 to 2273 K. Analysis of the data using the model of Mullins showed that surface diffusion was the dominant mechanism for mass transport. The results were compared with other similar published work on alumina, and the following equation for surface diffusion was determined: $$D_s (cm^2 sec^{ - 1} ) = 4.05 x 10^5 exp - (452kJ mol^{ - 1} /RT).$$      

Improved corrosion protection of aluminum alloys by electrodeposited silanes

Organofunctional silanes recently have emerged as outstanding, environmentally friendly corrosion protectors for metal substrates, compared with conventional chromate treatments. A simple immersion technique is typically used to coat the metal surface with silane films. However, the thickness and uniformity of the films are uncontrolled in this process. This paper proposes a new deposition technique for the silane films on the metal surface, i.e., by electrodeposition. Hydrolyzed silanes are water-soluble, ionized molecules, so they can be deposited on metals by electrodeposition. Various combinations of silane mixtures were tested at different voltages, pH values, bath concentrations, and exposure times on panels of alloy aluminum and mirror-polished ferro-plate. The surface structure was characterized by scanning electron microscopy (SEM) and ellipsometry. The resistance of the film to corrosion was investigated by direct current (DC) polarization and electrochemical impedance spectroscopy (EIS) techniques. Electrodeposition results in a more organized and uniform film with fewer pores, compared with immersed or dipped films. This paper was presented at the 2nd International Surface Engineering Congress sponsored by ASM International, on September 15–17, 2003, in Indianapolis, Indiana, and appears on pp. 320–26 of the Proceedings.     

Viscosity of compressed cold lake bitumen

Viscosity data over a temperature range of 37-115°C and a pressure range of 0-10 MPa gauge are presented for a Cold Lake bitumen sample. These data show that the compression of Cold Lake bitumen results in a significant increase in its viscosity. Results are compared with those from a similar study on an Athabasca bitumen sample. Also presented are two correlations for the effects of pressure and temperature on the viscosity of Cold Lake bitumen.     

Silicon Nitride Derived from an Organometallic Polymeric Precursor: Preparation and Characterization

Partially crystalline Si₃N₄, with nanosized crystals and a specific surface area greater than 200 m²/g, is obtained by pyrolysis of a commercially available vinylic polysilane in a stream of anhydrous NH₃ to 1000°C. This polymer does not contain N initially. Crystallization to high-purity α-Si₃N₄ proceeds with additional heating above 1400°C under N₂. The changes in crystallinity, powder morphology, infrared spectra, and elemental compositions, for samples annealed from 1000° to 1600°C under N₂, are consistent with an amorphous-to-crystalline transformation. Although macroscopic consolidation and local densification occur at 1400°C, volatilization and accompanying weight loss limit bulk densification. The effect of temperature on specific surface area is examined and related to the sintering process. These results are applicable to pyrolysis, decomposition, and crystallization studies of ceramics synthesized by polymeric precursor routes.     

Hydrogenation of unsaturated fatty esters during isobutane chemical ionization mass spectrometry

Hydrogenation of double bonds was observed to occur during the isobutane chemical ionization mass spectrometry (MS) of unsaturated fatty esters. Chemical ionization (CI) spectra of a series of methyl esters in the C16–C20 carbon range containing 0–4 double bonds showed a variety of ionization characteristics in the molecular ion cluster, including hydride abstraction, charge exchange, protonation and, for the unsaturated fatty acids (FA), hydrogenation of the double bond followed by protonation. The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

Monomer and amino resin modified tall oil fatty acid alkyds

Summary Monomer modified tall oil fatty acid trimethylolethane medium type of phthalic alkyds made by the High Polymer Alkyd Technique show improved properties in dry time, mar resistance, and flexibility as compared with monomer modified conventional prepared systems. Greater hardness, less color degradation, greater resistance to extended periods at high temperature, and alkali and detergent resistances result from the urea and melamine resin modifications of tall oil fatty acid High Polymer alkyds than is obtained with similarly modified conventional alkyds.