Quantitative analysis. (a) Graph representing the 25 technical topics by priority scores: black bars: high priority; dark grey bars: intermediate priority; light grey bars: low priority technical topics; and white bars: low interest technical topics. (b and c) Twenty-five technical topics’ profiles grouped according to the clustering based on the global priority: black lines: high priority; dark grey lines: intermediate priority; light grey lines: low priority technical topics; and dotted lines: low interest technical topics. (b) The graph clustering with the 25 technical topics and their pattern. (c) The technical topics analysed and classified by priority.