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Cross-breezes work when two windows are opposite of each other. Cross ventilation is a natural phenomenon where wind, fresh air or a breeze enters upon an opening, such as a window, and flows directly through the space and exits through an opening on the opposite side of the building (where the air pressure is lower).
Fourier transforms of two Kaiser windows. where: I 0 is the zeroth-order modified Bessel function of the first kind, L is the window duration, and; α is a non-negative real number that determines the shape of the window. In the frequency domain, it determines the trade-off between main-lobe width and side lobe level, which is a central ...
The net negative pressure on lower floors can induce outdoor air to infiltrate the building through doors, windows, or ductwork without backdraft dampers. Warm air will attempt to exfiltrate the building envelope through floors above the neutral axis. Mechanical refrigeration equipment provides sensible and latent cooling during summer months.
Below the neutral plane the internal air pressure will be negative and external air will be drawn into the space through any intermediate level apertures. Buoyancy-driven ventilation has several significant benefits: {See Linden, P Annu Rev Fluid Mech, 1999} Does not rely on wind: can take place on still, hot summer days when it is most needed.
Vertical wind-speed profiles result in different wind speeds at the blades nearest to the ground level compared to those at the top of blade travel, which results in asymmetric load. [27] The wind gradient can create a large bending moment in the shaft of a two-bladed turbine when the blades are vertical. [ 28 ]
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The power law is often used in wind power assessments [4] [5] where wind speeds at the height of a turbine ( 50 metres) must be estimated from near surface wind observations (~10 metres), or where wind speed data at various heights must be adjusted to a standard height [6] prior to use.
To help compare different orders of magnitude, the following list describes various speed levels between approximately 2.2 × 10 −18 m/s and 3.0 × 10 8 m/s (the speed of light). Values in bold are exact.