The phrase "approach was restricted" is correct and usable in written English.
It can be used to describe a situation where access or methods of engagement were limited or constrained.
Example: "Due to safety concerns, our approach was restricted, and we had to find alternative methods to complete the project."
Alternatives: "access was limited" or "method was constrained."
The quadratic stream function approach was restricted to processes with axial flow direction.
However, this approach was restricted, because of the small-scale model, the small number of slot-openings and difficulties in measuring invisible airflows being observed.
For microbial organisms, this approach was restricted to the minority that could be grown in pure culture in the laboratory until Norm Pace and colleagues showed that one could sequence rRNAs directly from environmental samples [6], [7].
Unfortunately, this approach was restricted by the high concentrations needed for in vivo effects [ 19].
Further, their approach was restricted to identification of individual DMPs rather than differentially methylated regions (DMRs).
A problem that arose in this approach was restricted diffusion of oxygen and nutrients leading to cell death in the center of the tissue cubes.
However, this approach is restricted to circular ssDNA viruses, and the use of restriction analysis limits the types and numbers of viruses identified.
This approach is restricted to the case when the collision frequency does not depend on the macroscopic field, but no smallness on the initial data is required.
However, this approach is restricted because there are few long-term data sets available.
Moreover, the approach is restricted to gray-scale images, and only the application of the CAC to object segmentation is evaluated.
One obvious caveat to all of the above is that the interface approach is restricted to Amari style models with a Heaviside firing rate.
