The phrase "a relation has been" is correct and usable in written English.
It can be used when discussing the existence or establishment of a relationship in various contexts, such as mathematics, social sciences, or personal interactions.
Example: "In our study, we found that a relation has been established between the two variables."
Alternatives: "a relationship has been" or "a connection has been".
Experimental determination of such a relation has been difficult.
A relation has been established between the HFSS code calculations predicting a dominant role of box currents in the formation of parallel antenna near-fields and the experiment.
A relation has been proposed, using only the interfacial tension and viscosities of both components, to predict the growth rate of coarsening.
At 125 kV, a relation has been created showing that there was good correlation between the theoretical and experimental values of the transmission factors at the different thicknesses of the slag concrete which could be used to design the X-ray partitions walls.
On the ground of this experimental finding, a relation has been derived between the number of pellets contacting 1 m2 of the wall surface area and the average voidage within that bed region, and the ratio of the tube-to-pellet radii.
Moreover, a relation has been suggested of MRP subtypes and CD4 cell counts.
The annealing-induced expansion of SiO2 has been established as an important effect and a phenomenological relation has been identified for it.
From these results, a simple relation has been proposed for the estimation of the IrO2 loading for a given c0 and ω.
A similar relation has been shown, reported by Hoffman et al. and by us in a separate paper.
Through extensive experimental investigations and modelling on gear surface temperature variations, a general relation has been built up between gear surface temperature and gear load capacity.
In fact, a linear relation has been found between the temperature location of α relaxation and the crystal thickness estimated from the SAXS long spacing.
