Radiative zone

These complementary observational constraints indicate that another process participates to the transport of AM in solar-type stars, while MC and turbulence are successful in more massive stars. The two most likely candidates are the large-scale magnetic field which could be present in the radiative zone and the internal gravity waves (hereafter 1GW) which are generated by the external convective zone. As we just explained, the observations suggest that the efficiency of this process is finked to the growth of the convective enveiope. This is a characteristics of 1GW. 

Figure 6.3 The Sun s structure. C and R stand for convective zone and radiative zone, respectively.

Fig. 12. Convective regions for the 1.9M0, Z = 0.008 model during the first five thermal pulses. The He-intershell extends from about 0.52Mq to 0.56Mq. The teardrop-shaped pockets correspond to the flash-driven convective region that extends over most of the He-intershell. These have the effect of homogenizing the abundances within the He-intershell. Convective regions are shaded in green and radiative zones in magenta. The n-axis is nucleosynthesis time-step number, which is a proxy for time. For this model, the duration of the convective zones are about 250 years...

The gas in the convective outer layers of the Sun rotates faster at the equator than at the poles, and gas rotates almost uniformly in the radiative zone. This stmcture (including the presence of the tachocline zone, located at the interface between the latitude-dependent rotation of the convective zone and the rigid radiative interior) has been measured seismologically [13-15]. Gough McIntyre [16] argue that we must have a magnetic field in the radiative interior in order to explain the uniform rotation of the radiative zone. 

The GMF in the Snn s radiative interior beneath the tachocline must be stationary it seem s nnlikely that the rapidly oscillating field associated with the solar cycle would contribute significantly to the dynamics in the radiative zone, particnlarly in view of the 10 yr tachocline ventilation time (Gongh McIntyre [16]) stationary internal field). 

In fossil fuel-fired boilers there are two regions defined by the mode of heat transfer. Fuel is burned in the furnace or radiant section of the boiler. The walls of this section of the boiler are constmcted of vertical, or near vertical, tubes in which water is boiled. Heat is transferred radiatively from the fire to the waterwaH of the boiler. When the hot gas leaves the radiant section of the boiler, it goes to the convective section. In the convective section, heat is transferred to tubes in the gas path. Superheating and reheating are in the convective section of the boiler. The economizer, which can be considered as a gas-heated feedwater heater, is the last element in the convective zone of the boiler. 

If the gas volume is not isothermal and is zoned, an additional magnitude, the gas-to-gas total-exchange area QGj, arises (see Hottel and Sarofim. Radiative Tran.sfer, McGraw-Hill, New York, 1967, chap. 11). Space does not permit derivations of special cases only the single-gas-zone system is treated here. 

Treatment of Refractory Walls Partially Enclosing a Radiating Gas Another modification of the results in Table 5-10 becomes important when one of the surface zones is radiatively adiabatic the need to find its temperature can be eliminated. If surface A9, now called A, is radiatively adiabatic, its net radiative exchange with Aj must equal its net exchange with the gas. 

An equation representing an energy balance on a combustion chamber of two surface zones, a heat sink Ai at temperature T, and a refractory surface A assumed radiatively adiabatic at Tr, inmost simply solved if the total enthalpy input H is expressed as rhCJYTv rh is the mass rate of fuel plus air and Tp is a pseudoadiabatic flame temperature based on a mean specific heat from base temperature up to the gas exit temperature Te rather than up to Tp/The heat transfer rate out of the gas is then H— — T ) or rhCp(T f — Te). The... 

Simulation by the improved Euler method has shown that a significant radiative heat transfer must be present before reaction zone migration can be demonstrated. 

The room models implemented in the codes can be distinguished further by how detailed the models of the energy exchange processes are. Simple models use a combined convective-radiative heat exchange. More complex models use separate paths for these effects. Mixed forms also exist. The different models can also be distinguished by how the problem is solved. The energy balance for the zone is calculated in each time step of the simulation. 

Size makes a difference propagating and nonpropagating energy near- and far-field zones radiative transfer... 

Fig. 1. Evolutionary tracks (labelled in Mq) and isochrones (in Myr) for low-mass stars taken from two models [8,31]. The epochs of photospheric Li depletion (and hence Li-burning in the core of a fully convective star or at the convection zone base otherwise) and the development of a radiative core are indicated. The numbers to the right of the tracks indicate the fraction of photospheric Li remaining at the point where the radiative core develops and at the end of Li burning.

The radiative heading of a planet from the local start to produce a surface temperature on the planet that will allow liquid water. From these calculations, estimates of global warming contributions can be made. A continually habitable zone allows for the variations in stellar flux as it evolves... 

DGE a AC AMS APCI API AP-MALDI APPI ASAP BIRD c CAD CE CF CF-FAB Cl CID cw CZE Da DAPCI DART DC DE DESI DIOS DTIMS EC ECD El ELDI EM ESI ETD eV f FAB FAIMS FD FI FT FTICR two-dimensional gel electrophoresis atto, 10 18 alternating current accelerator mass spectrometry atmospheric pressure chemical ionization atmospheric pressure ionization atmospheric pressure matrix-assisted laser desorption/ionization atmospheric pressure photoionization atmospheric-pressure solids analysis probe blackbody infrared radiative dissociation centi, 10-2 collision-activated dissociation capillary electrophoresis continuous flow continuous flow fast atom bombardment chemical ionization collision-induced dissociation continuous wave capillary zone electrophoresis dalton desorption atmospheric pressure chemical ionization direct analysis in real time direct current delayed extraction desorption electrospray ionization desorption/ionization on silicon drift tube ion mobility spectrometry electrochromatography electron capture dissociation electron ionization electrospray-assisted laser desorption/ionization electron multiplier electrospray ionization electron transfer dissociation electron volt femto, 1CT15 fast atom bombardment field asymmetric waveform ion mobility spectrometry field desorption field ionization Fourier transform Fourier transform ion cyclotron resonance... 

The dynamic calculations include all beams with interplanar distances dhki larger than 0.75 A at 120 kV acceleration voltage and thickness between 100 A and 300 A for the different zones. The structure factors have been calculated on the basis of the relativistic Hartree - Fock electron scattering factors [14]. The thermal difiuse scattering is calculated with the Debye temperature of a-PbO 481 K [15] at 293 K with mean-square vibrational amplitude

= 0.0013 A following the techniques of Radi [16]. The inelastic scattering due to single-electron excitation (SEE) is introduced on the base of real space SEE atomic absorption potentials [17]. All calculations are carried out in zero order Laue zone approximation (ZOLZ). 

The decrease in temperature predicted by the analysis is relatively small and has not been observed experimentally. Experiments with higher precision and accuracy are warranted for checking if this is an artifact of the present chemistry that does not include the effects of higher hydrocarbon formation and radiative heat loss. The peak temperature was found to decrease because of a decrease in the peak volumetric heat release rate caused by a broadening of the reaction zone. 

The pressure at which extinction occurs depends on the size of the strand. Both theoretical predictions and our observations of the flame indicate that the A/PA and O/F flame zones are thick enough (order of millimeters) at the extinction pressure for the flame to be susceptible to convective cooling by the entrained ambient gases as well as to a significant loss of available heat owing to escape of unreacted AP from the A/PA flame zone. No evidence has been found to show that radiative heat loss from the propellant surface is a major factor. However, Fein-auer s (27) results indicate that it is a contributory factor when carbon black has been added to the propellant. 



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