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Different types of noise are generated by different devices and different processes. Thermal noise is unavoidable at non-zero temperature (see fluctuation-dissipation theorem), while other types depend mostly on device type (such as shot noise, [1] [3] which needs a steep potential barrier) or manufacturing quality and semiconductor defects, such as conductance fluctuations, including 1/f noise.
The torsional deflection of a simple cylinder cannot radiate efficiently acoustic noise, but with particular boundary conditions the stator can radiate acoustic noise under torque ripple excitation. [8] Structure-borne noise can also be generated by torque ripple when rotor shaft line vibrations propagate to the frame [9] and shaft line.
Full-tower computer cases may contain multiple cooling fans. At the top of the case is a fan controller. Fan control is the management of the rotational speed of an electric fan. In computers, various types of computer fans are used to provide adequate cooling, and different fan control mechanisms balance their cooling capacities and noise they ...
Where noise is an issue, larger, slower-turning fans are quieter than smaller, faster fans that can move the same airflow. Fan noise has been found to be roughly proportional to the fifth power of fan speed; halving the speed reduces the noise by about 15 dB. [22] Axial fans may rotate at speeds of up to around 38,000 rpm for smaller sizes. [23]
When an electric motor, AC or DC, is first energized, the rotor is not moving, and a current equivalent to the stalled current will flow, reducing as the motor picks up speed and develops a back EMF to oppose the supply. AC induction motors behave as transformers with a shorted secondary until the rotor begins to move, while brushed motors ...
A motor that relies on a component oscillating at an ultrasonic frequency. ultrasonics Term for the field of study pertaining to pressure oscillations in air or other media that are above the range of human hearing. ultrasound Sound having a frequency above the range of normal human hearing. A portmanteau of the former description of ...
The former CEO of Abercrombie & Fitch (A&F) has dementia and late onset Alzheimer's disease, his legal team has said in a court document filed in New York.
A finned air cooled heatsink with fan clipped onto a CPU, with a smaller passive heatsink without fan in the background A 3-fan heatsink mounted on a video card to maximize cooling efficiency of the GPU and surrounding components Commodore 128DCR computer's switch-mode power supply, with a user-installed 60 mm cooling fan.