Steady state nature

White, W. H. (1984). Does the photochemistry of the troposphere admit more than one steady state Nature 309,242-244. 

Model instability is demonstrated by many of the simulation examples and leads to very interesting phenomena, such as multiple steady states, naturally occurring oscillations, and chaotic behaviour. In the case of a model which is inherently unstable, nothing can be done except to completely reformulate the model into a more stable form... 

Two types of Cr + luminescence centers have been found in steady-state natural alexandrite, characterized by J -lines at approximately 680 and 692 nm, accompanied by very many M-lines of Cr-Cr pairs (Tarashchan 1978). Those centers have been identified as connected with substitutions of AP" in different structural sites. It was found that natural alexandrites with very rare exceptions are characterized by very low CL intensities (Ponahlo 2000). Pulse CL study revealed that the spectrum consists of a relatively broad red band peaking at 685-695 nm, accompanied by narrow lines with the strongest one at 679 nm and the weaker ones at 650,655,664,700,707 and 716 nm. All lines and bands have been ascribed to several Cr + centers (Solomonov et al. 2002). The natural chrysoberyl and alexandrite in our study consisted of six samples. The laser-induced time-resolved technique enables us to detect two different Cr and possibly Mn + and V emission centers (Figs. 4.54-4.55). 

An automated tracer injection system was utilized to dispense tracers into the fracture regime of well 4014 under natural gradient conditions (Figure 1.2(b)). Two long-term, steady-state natural gradient experiments, each with a duration of 1.5 to 2... 

A steady state natural population, characterized by a continuous generation/destruction (birth/ death) cycle, is usually typified by an age structure similar to that in Figure 1, the cumulative curve defining all necessary parameters of a given population. These are its half-life mean age hnean> d obUvion age or life expectancy... 

V V Azatyan, Cham processes and non steady state nature of surfaces, Usp Khim, 54 33 (1985)... 

Additional experiments have been conducted that varied A from 0.7 to 3.0, holding all other feed conditions constant.8 Dual steady-state operation was observed for the entire range tested providing more evidence that the water amount in the feed composition is probably the dominant factor. This type of experiment was repeated for a different CO feed concentration and nearly the same behavior was recorded. This dual steady-state nature persists for a wide range of lambda, which points to the fact that dual steady state is more influenced by feed composition and more specifically by water amount. Since water has high heat capacity, this may temper the heat rise and delay the onset of H2 oxidation reaction. 

When the MWD was calculated, it was assumed that polymerization is of steady-state nature, that the activity of catalyst surface does not change with time, and that monomer concentration on the catalyst surface and kv are constant with time. 

An imposed temporal change of Tw, other than the step change, is also of interest. In fact, because the heat capacity of any body or wall is finite, a step change could never be achieved. If the time constant associated with the prescribed change in T is much larger than th the heat transfer at each instant in the transient can be accurately calculated from the steady-state natural convection equation this is called a quasi-static transient. From the above estimates of tt it will be appreciated that the quasi-static approximation will usually be valid for gases. 

In a continuous furnace, the load is fed into and out of the combustor constantly. The feed rate may change sometimes due to conditions upstream or downstream of the combustor or due to the production needs of the plant, but the process is nearly steady state. This makes continuous processes simpler to test as there is no need to include time as a variable in the analysis. It is often easier to make meaningful measurements in continuous processes due to their steady-state nature. 

The preceding discussion showed that steady-state natural convection often leads to undesirable macrosegregation. It also has been shown by Gill (11) that natural convection flows may become unstable, and... 

Gas-solid reactions have several aspects in conunon with reactions catalyzed by a porous solid, discussed already in Chapter 3. In the present case too, transport eflects and reaction have to be considered simultaneously. Again it depends on the relative magnitudes of the rate of transport and the rate of reaction whether or not important gradients inside and around the particle are built up or not. There is one essential difference, however with gas-solid reactions the conditions inside the particle change with time, since the solid itself is involved in the reaction. The process is therefore essentially of a non-steady-state nature. 

The reactor model chosen is one dimensional and heterogeneous with interfacial gradients. Intraparticie gradients are accounted for implicitly throi the fit of the experimental data by means of Eq. 1. The operation is adiabatia Furthermore, as mentioned already, the operation is of a non-steady-state nature, since the oxidation takes place in a zone that gradually moves through the reactor. 

The steady-state nature of the turbulence can be verified by checking that the integrals in [8.5] do not depend on time t from which they are calculated. The recording duration of T should be sufficiently long for the calculated average value to be independent from T. From an experimental standpoint, studying steady-state turbulence constitutes a dramatic simplification. All that is needed is to cany out one experiment of sufficiently long duration. 

Investigations of the complete DHR heat sink (DHX, stack and dampers) under steady state, natural convection and transient operation conditions, have shown that no problems... 

Vyas, H.P., Venkat Raj, V., Nayak, A.K., 2010. Experimental investigations on steady state natural circulation behavior of multiple parallel boiling channel system. Nuclear Engineering and Design 240, 3862—3867. 

Owing to the steady-state nature of the spherical diffusion at the microelectrode, the limiting current should be independent of potential sweep rates at lower sweep rates. As the sweep rate increases, the contribution of planar diffusion increases. The value of sweep rate at which planar diffusion begins to significantly interfere depends on the size of microelectrode. 

FIG. 8. Steady state natural circulation flow in UDLs without considering local losses. 

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