Unstable stratification

It is known that logarithmic profiles like (1.1) or (3.134) are proved however for only neutral stratification conditions. Some changes in the formulas are required to account for stable or unstable stratification conditions what will be discussed in the Section 3.3.3, formulae (3.141). 

The air over the SCS is highly unstable, because it contains heated and light humid air portions causing buoyancy and natural convection, and thus an additional turbidity (an unstable stratification). Monin and Obukhov [435] suggested to account this by adding a linear term to the logarithmic one (1.1). Here, an alternative way of Nickitin [466] is used that suggests the universal Karman constant to be a known empirical function of the Richardson number ... 

The upwelling of heavy bottom water into the surface layer at the left wall and the subsequent advection toward the right wall causes an unstable stratification that forces vertical convection leading to an irreversible loss of salt from the bottom layer into the... 

Planck hold that when R, < 0, stratified fluid is unstable stratification when R, = 0, sstratified fluid is homogeneous fluid when R, > 0, sstratified fluid is stable stratification when R,. > 2, turbulence is inhibited. In 1931, Taylor, after further analysis that the upper limit of stability of stratified fluid R(>1. 

Although the first superheater is stable with respect to density wave oscillations, even without orifices, we have to expect flow reversal in some fuel assemblies of the first superheater of a three-pass core at low mass flow rates because of an unstable stratification... 

Vanadium phosphoms oxide-based catalysts ate unstable in that they tend to lose phosphoms over time at reaction temperatures. Hot spots in fixed-bed reactors tend to accelerate this loss of phosphoms. This loss of phosphoms also produces a decrease in selectivity (70,136). Many steps have been taken, however, to aHeviate these problems and create an environment where the catalyst can operate at lower temperatures. For example, volatile organophosphoms compounds are fed to the reactor to mitigate the problem of phosphoms loss by the catalyst (137). The phosphoms feed also has the effect of controlling catalyst activity and thus improving catalyst selectivity in the reactor. The catalyst pack in the reactor may be stratified with an inert material (138,139). Stratification has the effect of reducing the extent of reaction pet unit volume and thus reducing the observed catalyst temperature (hot... 

Turbulence is generated by wind shear in the surface layer and in the wake of obstacles and structures present on the earth s surface. Another powerful source of turbulent motion is an unstable temperature stratification in the atmosphere. The earth s surface, heated by sunshine, may generate buoyant motion of very large scale (thermals). 

Lindahl B, Andren B, Ohlsson J, Venge P, Wallentin L. Noninvasive risk stratification in unstable coronary artery disease exercise test and biochemical markers. FRISC Study Group. Am J Cardiol 1997 80 40E-4E. 

Collinson J, Flather MO, Fox KA et al. Clinical outcomes, risk stratification and practice patterns of unstable angina and myocardial infarction without ST elevation Prospective Registry of Acute Ischaemic Syndromes in the UK (PRAIS-UK). Eur Heart J 2000 21 1450. 

Holmvang L, Clemmensen P, Wagner G, Grande P. Admission standard electrocardiogram for early risk stratification in patients with unstable coronary artery disease not eligible for acute revascularization therapy a TRIM substudy. Thrombin inhibition in myocardial infarction. Am Heart J 1999 137 24. 

Holper EM, Antman EM, McCabe CH et al. A simple, readily available method for risk stratification of patient with unstable angina and non-ST elevation myocardial infarction. Am J Cardiol 2001 87 1008. 

The effect of temperature stratification on the atmosphere can be illustrated by considering the different forms a plume may assume. The form of a plume is determined essentially by the relation of the plume release point to any stable, neutral, and unstable layers that may be present the basic forms have been summarized by Slade (1968) and Arya (1999). In a stable layer, vertical mixing of the plume will be limited, and the plume will fan out in the horizontal plane. If a plume is released into a neutral layer capped by a stable layer, the plume will mix vertically throughout the entire depth of the neutral layer. If a plume is released into a neutral layer... 

M. J. Tanasijevic, C. P. Canon, and E. M. Antman The role of cardiac troponin-I (CTnl) in risk stratification of patients with unstable coronary artery disease. Clinical Cardiology 22, 11 (1999). 

The troponins have been used successfully in the diagnosis of Ml and in the risk stratification of patients with unstable angina. 

The model applies a Gaussian plume model up to a specified transition distance, which is dependent on atmospheric stability 200 m for unstable, 500 m for neutral, and 1000 m for stable stratification, respectively. Outside this nearby zone, the gradient-transfer approach is used for computing the diffusion in the vertical direction. 

Dinckal, M.H., et al., QT dispersion in the risk stratification of patients with unstable angina correlation with clinical course, troponin T and scintigraphy. Acta Cardiol, 2004. 59(3) p. 283-9. 

While the cold container bottom yields a stably stratified configuration right from the start, the unstable density stratification at the cool top of the container may result in a Rayleigh-Benard instability [93]. In the third and fourth inset of Figure 9.2, the instability is observed as cold liquid draining down from the top into the bulk. 

The chapter begins with a summary of 15 points towards efficient storage, handling and use, together with some recommendations to prevent stratification and unstable evaporation behaviour, including roll-over. 

This stratification in a cryogenic liquid ntixture and density equilibration inevitably leads to unstable evaporation, which has acquired the name rollover . This unstable evaporation takes place when the stratified layers spontaneously mix, leading to a rapid and extended increase in bod-off rate above the normal BOR, which continues until the heat of ntixing, and the thermal overfdl in the lower layer, have been absorbed by the latent heat of vaporisation in the excess bod-off vapour. 

The feomdity of polar and sub-polar waters is, in part, explained by the variable sea ice cover. The freezing process enriches the surface water with brine, which renders the stratification of upper ocean layers unstable. This leads to convection and the up-welling of nutrient-rich water to the surface where, in the presence of sunlight, the food chain of plankton-fish-marine mammals is initiated. 

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