For a typical steel framed 30 ft by 30 ft office building bay, the fre-quency will be in the 5-8 Hz range. Frequency is a function of span (the longer the span, the lower the frequen-cy) and weight supported (the heavier the floor and the supported contents, the lower the frequency).
The following medical conditions are some of the possible causes of Skin color changes. There are likely to be other possible causes, so ask your doctor about your symptoms. 1  Causes of skin whitening:  Vitiligo.
Causes of White Spots on Skin. Your skin gets its color from melanin. Melanin is produced by cells called melanocytes, and it gives pigment to hair, skin, and eyes. People with dark skin have more melanin than light-skinned people, which is the reason why their skin is darker and white spots are more noticeable.