"a substantial extension of" is correct and usable in written English.
It is usually used to describe a period of time that has been extended or lengthened. For example, "Due to the current health crisis, the school board has granted a substantial extension of the school year."
In this paper, a substantial extension of the SEM is introduced and systematically optimised to create a realistic turbulence field based on von Kármán velocity spectra.
To point out essential issues to be addressed, the paper proposes a PKM for Development (PKM4D) framework as a substantial extension of a current framework focusing on ICT4D (Information and Communications Technologies for Development).
In this paper we describe a substantial extension of Marxan called Marxan with Zones, a decision support tool that provides land-use zoning options in geographical regions for biodiversity conservation.
This paper further presents a substantial extension of existing dune landscape simulation models by incorporating vegetation in the algorithm, enabling more realistic investigations into the self-organization of coastal dune systems.
Doping in the range 1-12% (atomic) induces lattice distortion with cell volume increase and a substantial extension of the visible absorption range due to a band-gap narrowing of about 0.45 eV for the highest doping level.
An analysis of the timing of annual maximum floods indicates a substantial extension of the potential flood period from around 7 months under current climate conditions up to the whole year in future scenarios.
The length of the contract is undisclosed, but is believed to be a substantial extension to the two-year deal he signed in 2013.
The article is a substantial extension and a continuation of the work published in [43] in which the focus was rather on facial landmark detection.
It could, in time, lead to a more substantial extension of the Indochina war to Thailand itself.
Fassel has earned a substantial extension, at least three years, of his contract through next season.
This enhanced second edition to "Scanning Probe Microscopy" (Springer, 2015) represents a substantial extension and revision to the part on atomic force microscopy of the previous book.
