The phrase "at a certain epoch" is correct and usable in written English.
It can be used to refer to a specific period in history or time, often in a more formal or literary context.
Example: "The discoveries made at a certain epoch changed the course of scientific understanding."
Alternatives: "during a specific era" or "in a particular period".
SV models at a certain epoch are separated into advective and non-advective parts.
Thus, once both bo and o are given at a certain epoch, the non-advective SV coefficients na can always be determined, whatever the flow is like.
In this section we describe our method to extract the non-advective or non-geostrophic SV for certain MF and SV models given at a certain epoch.
From this statistics, in Fig. 8c the average number of successful reaches obtained at a certain epoch is shown.
"He'll be remembered as a colorful character in a certain epoch in Chicago's history," said Dick Simpson, a professor of political science at the University of Illinois at Chicago, referring to the racial divisiveness and corruption that have characterized politics here.
At certain epochs several different styles of handwriting existed simultaneously, so that there is no straight line of development.
Earlier, in the first programme, Sir Kenneth said that "at certain epochs man has felt conscious of something about himself – body and spirit – which was outside the day-to-day struggle for existence and the night-to-night struggle with fear... .. and closing another episode, he said, talking about the pessimism that followed the break-up of Christendom.
Two fate determination rules are as follows: (i) For Rule I, the fate will be determined if it satisfies the conditions that (1) the fate can sustain the behaviors at a certain over-threshold state within a given length of time, and (2) the time epoch of the certain over-threshold in (1) is earlier than the other fate candidate.
Then, at a certain point, it works.
But at a certain fundamental level, familiar.
Leaders were retired at a certain age.
