The phrase "a narrow boundary" is correct and usable in written English.
It can be used to describe a limited or restricted area, either physically or metaphorically.
Example: "The researchers found that the species thrived only within a narrow boundary of temperature and humidity."
Alternatives: "a tight limit" or "a restricted range".
The use of such a narrow boundary can lead to misleading results and perverse decisions.
The results suggest a narrow boundary between mild and severe pain that interferes with function.
The coordinate points that mark transition to shear localization form a narrow boundary layer ∼23% of the channel thickness.
The area has long been among the most dangerous and heavily militarized in the world, with the two nuclear-armed rivals staring at each other over a narrow boundary.
Moreover, the proposed method eliminates the chattering effects by smoothing the control law in a narrow boundary layer for generating fixed switching pulse for both shunt and series converter.
In the second, thermal properties have been assumed constant in the bulk, but allowed to vary in a narrow boundary region adjacent to the wall without an additional resistance so that both temperature and temperature gradient are continuous throughout both regions.
Gainsbourg turns, before our eyes, from a skinny young nightclub performer in a trim tuxedo into a shaggy and grizzled talk-show fixture, all the while walking the narrow boundary between repulsiveness and charm.
With cunning agility, "Luminous Motion" tiptoes along the narrow boundary between fantasy and reality.
The best thing about this Wonka, who tiptoes on the narrow boundary between whimsy and creepiness, is that he defies assimilation or explanation.
Such an MHD duct flow is convection-dominated and its solution may exhibit localized phenomena such as boundary layers, namely, narrow boundary regions where the solution changes rapidly.
Politicized evaluations, narrow boundary setting, data gaps and simplified assumptions are frequently seen as problems in EIA that must be addressed.
