Sastrugi breaking equipment—ripples and waves are often undercut and the surface is hard and unforgiving, with constant minor topographic changes between ridge and trough. The words "sastrugi" and "zastrugi" are Russian-language plurals; the singular is "sastruga" or "zastruga". The form "sastruga" started as the German-language transliteration of the Russian word заструга (plural: заструги). A Latin-type analogica singular "sastrugus" is used in various writings on exploration of the South Pole, including Robert Falcon Scott's expedition's diaries and Ernest Shackleton's "The Heart of the Antarctic". Under the action of steady wind, free snow particles accumulate and drift like the sand grains in barchan
Surface acoustic wave electrical signals and vice versa by exploiting the piezoelectric effect of certain materials (quartz, lithium niobate, lithium tantalate, lanthanum gallium silicate, etc.). These devices are fabricated by photolithography, the process used in the manufacture of silicon integrated circuits. SAW filters are now used in mobile telephones, and provide significant advantages in performance, cost, and size over other filter technologies such as quartz crystals (based on bulk waves), LC filters, and waveguide filters. Much research has been done in the last 20 years in the area of surface acoustic wave sensors. Sensor applications include all areas of sensing (such as chemical,