The phrase "a varies" is not correct in written English.
It seems to be an incomplete expression and lacks clarity in meaning.
Example: "In this context, a varies depending on the conditions set forth in the experiment."
Alternatives: "a differs" or "a changes".
Figure 4 shows the variation of emission spectra for the excitation area, A, varies from 1 × 10−3 to 3 × 10−3 cm2 at a constant pump intensity of 0.3 MW/cm2.
During the 1-0 inphasehase (until t≈110) input A varies within the interval [4.5…5.5] nM (logic "1") while input B is still varying within the range [0…0.05] nM (logic "0").
During stage (1) a fairly streamwise-uniform distribution of U is characterized by A s,t)≈1, while during stage (2) U is less uniform and A varies over a much larger range.
The porosity, structure and nitrogen-doped surface chemistry are analyzed by a varies of means, such as scanning electron microscopy, transition electron microscopy, N2 sorption, X-ray diffraction and X-ray photoelectron spectroscopy.
The hierarchical porosity, structure and nitrogen-doped surface chemical properties are proved by a varies of means, such as scanning electron microscopy, transition electron microscopy, N2 sorption, Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy.
The coefficient matrix A varies with rotor angular frequency.
