The phrase "a certain minimum time" is correct and usable in written English.
It can be used when specifying a required duration that is not precisely defined but is understood to be the least amount of time needed for a particular purpose.
Example: "To ensure the best results, the experiment must be conducted for a certain minimum time before any observations are made."
Alternatives: "a required minimum duration" or "a specified minimum period".
Important events like card, corner and goal continue over a certain minimum time span.
Grooming was recorded if the animal's body deformed over a defined criteria and over a certain minimum time period, while the animal was situated in the same place.
However, especially at higher urgencies, it was very difficult for the observers to rate on the 5-points scale the subjective visibility of the motion stimulus shortly after stimulus onset, as evidently this task requires a certain minimum time to be accomplished.
In addition, the number of uninterrupted episodes per hour with a muscle activity above the chosen discrimination level for a certain minimum of time (>1, 2.., 10 min), will be assessed, as well as the total relative duration of such episodes in the shift [ 76].
Practically speaking, this means that there should be a certain minimum period of time between the "new" prescription and the time when the previous antimicrobial prescription was issued.
One requires parents to certify that they have spent a certain minimum amount of time practicing driving with their children.
Conversely, initial dosage did not create observable effects on emotional support, but improvement was observed after exposure to a certain minimum dosage of time watching video exemplars.
The important point is this: Not just professional historians but most arbiters of our intellectual life feel that a certain minimum period of time needs to have passed and that certain canonical kinds of archival source should be available before anything written about this immediate past qualifies as history.
Following this notion, we assume that engaged item completion (i.e., solution behavior) involves taking at least a certain minimum amount of time required to read and understand the test instructions, process the stimulus' content, and finally give a response, whereas disengaged test-taking behavior means taking less time or guessing rapidly.
In order to guarantee a successful commutation in thyristor valves, a certain minimum commutating voltage-time area is required, and this is provided by a minimum extinction angle γmin.
Additional investigations by real-time FT-IR spectroscopy revealed that a certain minimum conversion of double bonds was required before the folding process could start.
