A ranking model contains a collection of ranking features to calculate the rank score of a particular item, for example a document, in the search results.The type of content that is ranked determines the set of ranking features that the ranking model uses and the relative importance of these different ranking features.
Your activity appears to be coming from some type of automated process.
The ranking model is at the core of this calculation.
In most cases, you can influence relevance by using the available Share Point 2013 ranking models in combination with query rules without having to consider customizing any ranking models.
In this article: There are several ranking models in Share Point 2013 that are optimized for specific cases.
These ranking models provide an effective ranking of results without any further customization.Share Point 2013 provides the following types of ranking models: Default ranking model for the Search service application.