The phrase "are essential issues" is correct and usable in written English.
It can be used when discussing topics or matters that are of great importance or necessity in a particular context.
Example: "In our discussion about climate change, we must recognize that resource management and sustainability are essential issues that need to be addressed."
Alternatives: "are critical matters" or "are vital concerns".
Formulations and numerical simulations of shape memory process are essential issues in mechanical characterizations of shape memory polymers (SMPs).
Measurement and evaluation of the prestress losses in the reinforced structures are essential issues for structural design and healthy assessment.
These are essential issues, particularly if we are to achieve the government's laudable aim to make Britain's roads the safest in the world.
Structural and functional diversity and interactions within the community as well as with the hosts are essential issues in understanding microbial ecosystems.
When a large-scale network is to be constructed jointly by several agents, both the optimal network design and the fair allocation of its cost are essential issues.
The inherent characteristics of renewable energy, such as highly random fluctuation and anti-peak, are essential issues that impede optimal design of a combined cooling, heating and power (CCHP) system.
On that basis, it is not surprising that there might be complaints relating to the small details of the inspection which may be essential issues as far as we are concerned and the way we see the whole thing.
Energy conservation in building arena is essential issue for achieving sustainable environment.
For the design of superconducting fault current limiter, the research about recovery time and AC loss is essential issue because this characteristic is closely related to stability and efficiency.
First, we obtained a sound, complete and decidable algorithm for reasoning in ARTIGENCE knowledge base, with decidability being an important indicator that the computational complexity of the language might be essential issue for practical applications.
