Sastrugi Sastrugi Sastrugi, or zastrugi, are sharp irregular grooves or ridges formed on a snow surface by wind erosion, saltation of snow particles, and deposition, and found in polar and open sites such as frozen lakes in cold temperate regions. The ridges are usually perpendicular to the prevailing winds; they are steep on the windward side and sloping to the leeward side. Smaller irregularities of this type are known as ripples (small, ~10 mm high) or wind ridges. Larger features are especially troublesome to skiers and snowboarders. Traveling on the irregular surface of sastrugi can be very tiring, and can risk
Surface acoustic wave local oscillator has been mixed with the received signal, and so a filter with a fixed frequency and high Q provides excellent removal of unwanted or interference signals. In these applications, SAW filters are almost always used with a phase locked loop synthesized local oscillator, or a varicap driven oscillator. In seismology surface acoustic waves travelling along the Earth's surface play an important role, since they can be the most destructive type of seismic wave produced by earthquakes. In recent years, attention has been drawn to using SAWs to drive microfluidic actuation and a variety of other processes. Owing to