# neutral stability

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Related to neutral stability: indifferent stability

## neutral stability

[′nü·trəl stə′bil·əd·ē]
(control systems)
Condition in which the natural motion of a system neither grows nor decays, but remains at its initial amplitude.
(meteorology)
The state of an unsaturated or saturated column of air in the atmosphere when its environmental lapse rate of temperature is equal to the dry-adiabatic lapse rate or the saturation-adiabatic lapse rate respectively; under such conditions a parcel of air displaced vertically will experience no buoyant acceleration. Also known as indifferent equilibrium; indifferent stability.

## neutral stability

Neutral stability.
i. In meteorology, it is that condition in which the observed lapse rate is equal to the dry adiabatic lapse rate. A parcel of dry air will remain at its new level once it is pushed up because its temperature will be the same as that of the surrounding air.
ii. In aerodynamics, it means that an aircraft will tend to stay in its most recently commanded attitude or condition, without oscillations, and it will neither tend to return to its previous state or diverge from its new attitude. Also called neutral equilibrium or neutral static stability.
References in periodicals archive ?
The coexisting curve and neutral stability curve divide the whole area into stable, metastable, and unstable areas, just as Figure 2 has shown.
The linear analysis is studied to get the neutral stability curve.
Caption: Figure 1: The neutral stability line in the headway-sensitivity space.
According to (13), we can find that the neutral stability condition of the proposed model depends on the anticipation parameters [p.sub.1], [p.sub.2], [p.sub.3] response to the gap while having no relation with the anticipation parameters [q.sub.1], [q.sub.2], [q.sub.3] response to the velocity difference.
In Figure 5, the region above the neutral stability line means the stability region where traffic jam does not occur when small disturbances are applied.
In derivation of the neutral stability equation of stratified liquid-liquid flow, Brauner [13] found that the lower fluid of stratified flow is sometimes much faster, so the velocity of the upper phase may be neglected in neutral stability condition.

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