people. It can wipe away farms, trees and many more heavy items. Floods occur at irregular intervals and vary in size, duration and the affected area. It is important to note that water naturally flows from high areas to low lying areas. This means low-lying areas may flood quickly before it begins to get to higher ground. Flooding is extremely dangerous and has the potential to wipe away an entire city, coastline or area, and cause extensive damage to life and property. It also has great erosive power and can be extremely destructive, even if it is a foot high. A tsunami (pronounced sue-nahm-ee) is a series of huge waves that can cause great devastation and loss of life when they strike a coast. Tsunamis are caused by an underwater earthquake, a volcanic eruption, an sub-marine rockslide, or, more rarely, by an asteroid or meteoroid crashing into in the water from space. Most tsunamis are caused by underwater earthquakes, but not all underwater earthquakes cause
- kirjeldada erinevaid kulumise mudeleid mitmesugustes tribosüsteemides. Nende uuringute eesmärgiks on: - arendada välja palju täpsemad kulumismudelid, - saada fundamentaalsed seosed materjalide struktuuri ja omaduste mõjust kulumisele, - parandada materjalide (või selle pinna) kulumiskindlust erinevates kulumistingimustes. On erinevaid kulumise klassifitseerimise skeeme, kuid peamiselt on jagatakse järgmisteks liikideks : - abrasiivkulumine (abrasive wear), - erosioonkulumine (erosive wear), - hõõrde- e. liugekulumine (sliding wear), - frettingkulumine (fretting wear), - korrosioon-erosioon kulumine. Abrasiivkulumine all môeldakse tööpindade kulumist, mis on põhjustatud kõvema pinna mikrokonaruste või kontaktpindade vahele sattunud liikuvate (libisevate, rulluvate) abrasiivosakeste poolt. Selle tulemusena eraldub osakeste lõikava, kraapiva või paljukordse deformeeriva toime tulemusena kontaktpinnalt materjali. Plastse 4
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