The term "substantial increase of the" is correct and usable in written English.
You might use this phrase when describing how much something has changed, for example: The company reported a substantial increase of the overall profits this quarter.
It is entirely possible to stabilize euro bond markets and save the euro with a large increase of the European Financial Stability Facility and/or a substantial increase of the European Central Bank's purchase of government bonds.
Coxey hoped to persuade Congress to authorize a vast program of public works, financed by a substantial increase of the money in circulation, to provide jobs for the unemployed, but, despite the publicity his group received, it had no impact on public policy.
As expected, there is a substantial increase of the velocity values during the roto-percussion drillings.
However, this achievement results in a substantial increase of the encoding complexity or the encoding time.
Substantial increase of the CH2O signal and decrease of CH signal was observed as the jet velocity increases.
Over the energy range ≈ 0.2 – 1 MeV/nucleon a substantial increase of the charge states with energy was observed.
The new approach resulted in substantial increase of the Sn/Pt ratio in tin modified Pt/SiO2 catalysts.
The presence of coadsorbents, such as oxygen, also led to a substantial increase of the amount of tin anchored.
As a result, the rural nature of poverty has intensified, with a substantial increase of the share of poor living in rural areas.
Large-scale integration of wind therefore requires a substantial increase of the ability of wind plants to mitigate and survive grid disturbances.
Another significant drawback is a substantial increase of the PAPR that is caused by the high power values transmitted on the CCs correlated with the DCs.
