instability

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Related to Multidirectional Instability: AMBRI

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moving away from its original state when disturbed by an external force and to continue after that force has been withdrawn.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 aim of this case is to illustrate the use of these techniques in the management of a patient presenting with multidirectional instability of the shoulder.
Relevant biomechanics, multidirectional instability, and severe loss of glenoid and humeral bone.
Altchek DW, Warren RF, Skyhar MJ, Ortiz G: T-plasty modification of the Bankart procedure for multidirectional instability of the anterior and inferior types.
Neer CS II, Foster CR: Inferior capsular shift for involuntary inferior and multidirectional instability of the shoulder: A preliminary report.

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