Hotspots

The catalyst used for these studies was one that had been rejected by laboratory short tubular reactor experiments as a hotspot-type catalyst. This same type was recommended by another corporate lab with experience in catalyst formulations. The hotspot-type catalyst gave 3-... 

This result was checked by simulation of both CSTR measurements and calculations of tubular reactor incipient runaways. It should be noted that the predicted AT at inflection from CSTR experiments agrees well with measures in tubular simulation. At hotspot the AT to the AT at inflection is between 1.4 and 1.8. Using a multiplier of 1.4 as recommended by Nelson (1974) is safe. 

If ignition is assumed to occur in a hotspot formed at the electrode, the local release of potential energy W = QV/2 is directly proportional to charge while independent of electric field except in the immediate vicinity of the electrode, since this determines the local change in potential. The electric field near the electrode becomes increasingly uniform as electrode radius increases and eventually, uniform field breakdown conditions are approached (C-2.5.3). These concepts allow first approximations for effective energy to be made. First it is assumed that air breakdown occurs at 30 kV/cm and that the electric field is approximately uniform between about 2-5 mm from the electrode (C-2.5.2). Second, it is assumed that minimal ignition occurs in a 3 mm diameter hotspot formed sufficiently far from the electrode to minimize heat losses. This distance is assumed to be about 2 mm. 

Nadeau, M. L., 1995a, Transmittal of Software Management and QA Package for the HOTSPOT Codes, (HOTSPOT Version 7.01, Fidler version 7.0), ECS-EST-95-0077 SRC, August. 

Poor flow distributions may result in localized dry hotspots which, absent control of the temperature fluctuations, may cause rapid overheating. Temperature and pressure fluctuations, and poor flow distribution, are the main problems that accompany the use of two-phase micro-channels. 

The energy that powers terrestrial processes is derived primarily from the sun and from the Earth s internal heat production (mostly radioactive decay). Solar energy drives atmospheric motions, ocean circulation (tidal energy is minor), the hydrologic cycle, and photosynthesis. The Earth s internal heat drives convection that is largely manifested at the Earth s surface by the characteristic deformation and volcanism associated with plate tectonics, and by the hotspot volcanism associated with rising plumes of especially hot mantle material. 

Morgan, W. J. (1983). Hotspot tracks and the early rifting of the Atlantic. Tectonophysics 94,123-139. 

Diffenbaugh NS, Pal JS, Giorgi E, Gao X (2007) Heat stress intensification in the Mediterranean climate change hotspot. Geophys Res Lett 34 L11706. doi 10.1029/2007GL030000... 

This example was chosen to be sensitive to axial dispersion but the effects are fairly modest. As expected, conversions are lower and the hotspots are colder when axial dispersion is considered. See Figure 9.11. 

Consider a laminar flow tubular polymerizer with cooling at the tube wall. At what radial position will a hotspot develop at the tube wall, at the centerline, or at an intermediate radius Justify your answer. Will the situation change with heating at the wall ... 

Although the likelihood for biologically harm has not been assessed fully, for most EDCs the exposure concentrations in ambient environments (away from hotspots of chemical discharges) would suggest that they are insufficient to do so. Exceptions to this inclnde the case studies detailed in the previous section. It should, however, also be emphasized that most studies on the effects of EDCs under controlled laboratory conditions have not considered long-term chronic exposures encompassing full life cycles, and some wildlife species are exposed lifelong to some of the EDCs described earlier. 

Tvrdik T et al Molecular characterization of two deletion events involving Alu-sequences, one novel base substitution and two tentative hotspot mutations in the hypoxanthine phosphori-bosyltransferase gene in five patients with Lesch-Nyhan-syndrome. Hum Genet 1998 103 3H. 

B. S. Griffiths, Microbial-feeding nematodes and protozoa in soil their effects on microbial activity and nitrogen mineralization in decomposition hotspots and the rhizosphere. Plant Soil 164 25 (1994). 

Bourdon B, Langmuir CH, Zindler A (1996a) Ridge-hotspot interaction along the Mid-Atlantic Ridge between 37°30 and 40°30TST the U-Th disequilibrium evidence. Earth Planet Sci Lett 142 175-189... 

It has long been known that the source of hotspots is different from the source of... 

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