"drastic fluctuations" is a correct phrase in written English.
You can use it to refer to large and sudden changes in something over a period of time. For example, "The stock market has seen drastic fluctuations in recent weeks."
Habitats favourable for hominin occupation undoubtedly appeared and disappeared throughout much of Africa over and over again with the drastic fluctuations in tropical climates that occurred during the Pliocene and Pleistocene epochs.
Drastic fluctuations of wind power make rapid changes of connectivity level, global effective performance and percentage loss of load.
However, after the fault occurs at time 0.3 s, the voltages suffer from drastic fluctuations, as shown in Fig. 6c.
That involves drastic fluctuations in blood glucose levels: High glucose levels trigger major insulin secretion to soak it up, which then leads to a shortage of glucose.
Obstacles along the propagation paths between transmitter and receiver cause drastic fluctuations in the power level of the received signal too.
The capacity of wireless channel usually suffers either moderate or drastic fluctuations due to the signal attenuation, inter-user interference, fading and user mobility, and so forth.
Therefore, we suppose that h(x) has a strong nonlinearity although it will not have a drastic fluctuation.
The drastic fluctuation of international oil price will have a significant impact on China, the second largest oil consumer and the third oil-importing country in the world.
In response to the drastic fluctuation in feed flow rate and composition, owing to the unsteady cracking reaction, the adaptive control of membrane area is customized technically for the operation strategy.
Notably, within each regions CMCs are evenly distributed while densities of DMCs show drastic fluctuation across each tested region, perhaps reflecting the regulatory nature of those DMCs.
But her husband's death brings an end to her financial support, and drinking, pill-popping and drastic weight fluctuations take their toll.
