The phrase "main difficulties of" is a correct and usable phrase in written English.
It can be used when referring to the primary, or main difficulties that are encountered with a particular situation, event, problem, etc. For example: "The main difficulties of weight loss are staying disciplined and avoiding unhealthy cravings."
Design: The main difficulties of directly applying the conventional pendulum test to the elbow were the small inertia of the forearm and the uncomfortable posture.
The main difficulties of shaping of internal treads with the required accuracy in aluminium alloys caused by a built-up edge were studied in this paper.
We describe the main difficulties of dealing with static output feedback design and summarize the main features, advantages, and limitations of existing design methods.
One of the main difficulties of using carbon nanotubes for such applications is that existing manufacturing processes create a mix of nanotubes with a wide range of electronic properties.
Although this method is attractive in the sense that it bypasses the reference signal requirement, i.e., one of the main difficulties of the classical near-field acoustic holography, its degree of accuracy does not appear to be adequate.
The two main difficulties of using hydrogen peroxide in the presence of transition metal complexes are the homolytic cleavage generating OH radicals and the catalase reaction with formation of dioxygen.
The main difficulty of the coincidence of the source and collocation points then disappears.
The main difficulty of this option lies in layout of pipes due to the space constraints.
It still remained, however, to account for a common world which in fact remains the main difficulty of Yogachara.
MPC relies on a dynamical model of the building, which is the main difficulty of applying it.
This means that the hydrodynamic variables must project onto the family of eigenfunctions; this is the second main difficulty of the present problem.
