What is a Noisy-OR Model

I am interested with the paper "Noisy-OR Component Analysis and its Application to Link Analysis" published by Tomas Singliar and Milos Hauskrecht on JMLR 7 (2006). A very preliminary prerequisite to understand this paper is to know the "noisy-or" model. However, it seems that noisy-or is an old topic and no much can be found via Google. Fortunately, I got a very brief description from an old paper "Possibility theory and the generalized Noisy OR model". Snapshotting the section on Noisy OR as an image as attached:


From this paper, I also find the original paper that presents Noisy OR at the UAI's website.
Unfortunately, I do not have access to the full text in PDF format... :-(