The IEEE Xplore library has a very annoying way of serving up PDFs. The page has two frames, one's a small banner at the top and the bother is the PDF. Both Safari and Chrome keep the banner in focus so when I try to zoom I'm just zooming the banner. Here's a javascript bookmarklet to open that second frame as a proper page:
javascript:(function(){window.location.href=document.getElementsByTagName("frame")[1].src;})()