β Scribed by S.A. Collins; A.H. von Flotow; J.D. Paduano
No coin nor oath required. For personal study only.
The vibration produced by Stirling cryocoolers is incompatible with precision-pointing imaging instruments. This paper examines a vibration cancellation system that was designed for the expander of a Hughes tactical cooler. This system uses a customdesigned multi-axis counterbalance and an analogue implementation of an adaptive feedforward compensator. A non-linearity associated with the counterbalance is modelled, and its effect on the closed-loop system is assessed. In an initial test, the third harmonic of the expander's axial force was cancelled by 22-38 dB over a wide range of drive frequencies, with little effect on the other harmonics or the lateral vibrations.
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Vibration analysis of machines gains much in efficiency if periodic vibrations can be separated out from non-deterministic ones. The first part of this paper reviews the existing adaptive algorithms that may be used to achieve this goal. The presentation is carried out from the viewpoint of predicti
This paper presents the design and implementation of an active control mechanism for noise cancellation and vibration suppression within an adaptive control framework. A control mechanism is designed within a feedforward control structure on the basis of optimum cancellation at an observation point.
Figure Measured radiation patterns in the xαz and yαz planes for the proposed antenna shown in Figure ; f s 1867 MHz ing tolerances for the proposed design are much relaxed, compared to the compact CP design using inserted slits of w x unequal lengths 1 . Results have also been obtained showing tha