Я не уверен как правильно это перевести. Однако, мне кажется, что я где-то близок к истине.
Дело в том, что Swept Sine Vibration подразумевает контроль колебаний по разным параметрам в разных диапазонах частот. Вот как здесь описано:
There are many test parameters associated with swept sine. Most basically is that the vibration must be controlled through acceleration, displacement, or velocity just like a fixed-frequency test. Unlike the fixed-frequency vibration, we have the added option of controlling part of the range with one parameter, while other parts of the range are controlled by completely different parameters with different magnitudes. As an example, we might run a swept sine from 20 to 200 Hz with 20 to 50 Hz controlled with a 0.060" displacement, 50-150 Hz controlled with 3 g's acceleration, while 150-200 Hz is controlled with 6 g's of acceleration.
http://www.motorola.com/ies/MPTS/swept_sine1.html
Частота перехода между режимами контроля колебаний по разным параметрам называется crossover frequency:
Crossover frequency -- In a swept sine vibration test, the frequency at which the units of displacement, velocity or acceleration yields the same test level.
http://www.signalstar.co.uk/glossaryofterms.htm
Crossover Frequency -- In sinusoidal vibration testing, the unique foreign frequency at which the required displacement yields the desired acceleration and vice versa.
http://www.newport.com/file_store/PDFs/tempPDFs/Glossary_of_...

А эти параметры -- это (вибро)ускорение, (вибро)смещение и скорость колебаний. Они описаны здесь:
Vibration can be controlled through one of three interrelated variables:
Acceleration. Commonly expressed in g’s where 1 g equals the force of gravity. Numerically, 1 g is approximately 32 feet per second squared (ft/sec2) or 9.8 meters per second squared (m/s2).
Displacement. Measured in inches or mm. Most electrodynamic shakers have either 1 or 2 inches of peak-to-peak travel. This is the same as saying that they can move ± 0.5 or ± 1.0 inch respectively. Longer travel machines will generally be capable of higher vibrational stress levels.
Velocity. Measured in inches per second (in/sec) or meters per second (m/s). The magnitude of the velocity that the table is moving as it passes through the center of its up and down motion. Some vibration equipment manufacturers specify the shaker’s operational limits in terms of the maximum velocity that it can attain.
http://www.motorola.com/ies/MPTS/fixed_frequency_sine1.html