"sub level" is correct and is commonly used in written English
For example, you could say "The research has revealed interesting results at the sub level."
A quick dive is accomplished by filling a large tank or tanks with water, but when the desired depth is reached, the mixture of air and water is adjusted in other tanks, both to keep the sub level and to prevent it from plunging to a depth at which water pressure would crush it.
The mine, exploited by sub level stoping method and without backfills, was home to important phenomena of subsidences that before had led to the closure and then have compromised the surrounding areas.
The diagram also presents the drugs (decision alternatives) as the lowest level of the hierarchy; that is, a sub level of all other levels.
This sub-level is more than a place; it's a mental state.
And while plastic bags are unlikely to topple anything Mulberry produces, they carry their own sub-level status.
The group behind the attack – the Impact Team – breached Ashley Madison's servers last month, and this week released the data to the Dark Web: a sub-level of the internet that cannot be accessed through normal browsers.
Table 5 shows the correlations among three sub-level indicators of school learning environment and thirteen sub-level indicators of other four learning environments.
Correlations exist among these learning environments and their sub-level indicators.
In a multilevel setting, correlation at a sub-level is taken care of by inclusion of random parameters which are constant within the sub-level but are allowed to vary at the upper levels [18, 20, 37].
In consequence, these three specific sub-level indicators of family learning environment were all significantly correlated with those three sub-level indicators of workplace learning environment (see in Table 6).
The interesting architecture is featured with assembled lamina, while each lamina is constructed from agglomerative sub-level nanoflake array.
