The rules surrounding the use of the definite article in English are quite complex and confusing for many non-native speakers. For example, 'the' is never used before a person's name unless for particular clarification:
"Ron Howard's outside."
"The Ron Howard? The famous director?"
"Yep, that one."
Nevertheless, I hear many non-native speakers use it commonly before people's names. ("*Did you talk with the Steve yet?")
Note: I'm using the standard mechanism of marking incorrect or unusual usages with a star.
It doesn't matter in this case whether the writing is technical or informal, though it would be even rarer to use the emphatic 'the' from above in technical writing.
For other nouns, use of 'the' is so spotty as to be nearly idiomatic. Country names are a good example--for many years, English speakers referred to "The Ukraine", even though they didn't refer to (for example) "*The Russia." While this particular example has changed, many other examples still exist. Some are stylistic, with only minor variations in meaning and usage:
"The people elected him President in 1980."
"The people elected him the President of France in 1980."
The style for many years was to avoid the use of personal pronouns (I, we, you) in technical writing. This led to torturous constructions and overuse of the passive voice:
The results were originally published by one of the authors (Brown, 1977).
However, in the 90s and 00s, the style changed, and scientific articles started using 'we' or 'I':
I originally published these results in 1977 (Brown, 1977).
Some journals still refuse to adopt this style. In general, a more impersonal style is still preferred for most technical writing, because use of "I" makes it sound like the text is the author's opinion, rather than their presentation of facts.