Consider the example in the cropped image above. It shows an improper use of capitalization (indicated with the red underline).
What constitutes improper use?
Capitalization of nouns indicates a very specific instance as opposed to a more general case. This guideline explains why titles and other names are often capitalized; they indicate a specific instance rather than a general reference. Asking whether a reference connects to something specific or something in a more general sense can help writers determine whether or not to use capitalization.
Applying the guideline
By capitalizing reliability engineering, the author indicates a very specific instance, perhaps a special type of reliability engineering or a group or entity named Reliability Engineering. But the context of the use of that term makes clear that the author really uses reliability engineering as a reference to a general subject area.
Fortunately, such errors are easy to fix. And interestingly enough, the author actually used the term reliability earlier in the abstract with the correct application of capitalization; the word appears in lowercase. In my experience, these errors often appear consistently because the author thinks the guideline for proper usage is not what it really is. Errors which do not appear consistently often indicates ignorance about the guideline for proper usage. Either way, the fix is easy. Learn the proper guideline, and then apply it consistently.
And is it just me, or did anyone else notice that Tip #6 is posted on the 6th day of the month? There's some serendipity for you. Seriously, I didn't plan it that way!