References. 1  Top of page. 2  Abstract. 3  Circadian and homeostatic mechanisms in sleep. 4  The role of thalamus in sleep. 5  Intergeniculate leaflet and suprachiasmatic nuclei. 6  NREM and REM sleep. 7  Similarities between pineal melatonin production and spindle formation. 8  Spindles and melatonin in brain disorders. 9  DLMO and NREM sleep gate.
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A water hammer commonly occurs when a valve closes suddenly at an end of a pipeline system, and a pressure wave propagates in the pipe. It is also called hydraulic shock. This pressure wave can cause major problems, from noise and vibration to pipe collapse.o for a valve closing instantaneously, the maximum magnitude of the water hammer pulse is: where Î´ P is the magnitude of the pressure wave (Pa), Ï is the density of the fluid (kgm â3), a0 is the speed of sound in the fluid (ms â1), and Î´ v is the change in the fluid's velocity (ms â1).