instability

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instability

1. tendency to variable or unpredictable behaviour
2. Physics a fast growing disturbance or wave in a plasma

instability

[‚in·stə′bil·əd·ē]
(control systems)
A condition of a control system in which excessive positive feedback causes persistent, unwanted oscillations in the output of the system.
(physics)
A property of the steady state of a system such that certain disturbances or perturbations introduced into the steady state will increase in magnitude, the maximum perturbation amplitude always remaining larger than the initial amplitude.

instability

In a structure, the sudden loss of stiffness that limits its load-carrying capability, and in some cases results in the structure’s failure.

instability

instabilityclick for a larger image
i. A state of the atmosphere in which a parcel of air will continue to rise, if for any reason, it is pushed up. Any instability in the atmosphere means turbulent conditions exist. The environmental lapse rate (ELR) in this case will be higher than both dry and saturated adiabatic lapse rates. Dry adiabatic lapse rate (DALR) is the rate of decrease of temperature with height of a parcel of dry air lifted adiabatically. Its value is 3°/1000 ft. Saturated adiabatic lapse rate (SALR) is the lapse rate of a parcel of saturated air and its value is 1.5°/1000 ft.
ii. A tendency of a body to continue moving away from its original state when disturbed by an external force and to continue after that force has been withdrawn.
iii. The failure of structures, such as the buckling of plates and panels under compression, and the failure of struts under end loads.
References in periodicals archive ?
The difference in speed and energies between the two creates the very similar KH instabilities that we can observe in clouds.
Detailed dynamics of bubble instabilities were investigated as a function of time, at various flow rates of the cooling air and for different TURs and BURs.
All the materials showed interfacial instabilities when the narrow die-gap geometry was used.
It was to preserve and to extend the gains associated with low and declining inflation--and to avoid the instabilities and imbalances attendant to rising inflation--that we began the process of tightening one year ago.
Consequently, these two instabilities are considered the most likely mechanism of beaded fiber formation during the electrospinning of PHBV solutions.
Therefore, appearance of one of these bubble instabilities can greatly narrow the stable operating ranges of commercial productions.
The basic mechanisms responsible for these instabilities are similar in many ways to feedback encountered in loudspeaker systems.
Identifying the instabilities involved in fibrillation is difficult both theoretically and experimentally.
It was concluded that there are essentially two types of interfacial instabilities and that the MW had the strongest effect on the occurrence of the "zig-zag" instability due to high interfacial stress while the breadth of the MWD had a strong effect on the app earance of the "wave" instability.