is not needed", and "it must also be absolutely ready to go for at least 15 years" (Ashley, 1994, pp. 58-61).
A typical driver-side airbag consists of two circular pieces of fabric which have been stitched together. These airbags may hold as much as 60 liters of gas. In contrast, passenger-side units are roughly 3 to 5 times larger and more teardrop-shaped. These may include two vertical panels of fabric with a main horizontal panel between them. Side-impact airbags may be installed in trim, behind trim, or housed in a separate door unit. Door mounted airbags are often placed either in the armrest or upper body area ("Side-impact protection", 1994, p. 40). Crash detectors, or accelerometers, generally employ a crash-discrimination algorithm to evaluate any specific impact. In addition, a diagnostic circuit monitors system readiness and provides backup power during electrical failure. Each airbag also contains a gas generator and inflator device. This essentially consists of a steel or aluminum canister about 6 centimeters
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