SNIP measures contextual citation impact by weighting citations based on the total number of citations in a subject field.
SJR is a prestige metric based on the idea that not all citations are the same. SJR uses a similar algorithm as the Google page rank; it provides a quantitative and a qualitative measure of the journal’s impact.
The Impact Factor measures the average number of citations received in a particular year by papers published in the journal during the two preceding years.
© Thomson Reuters Journal Citation Reports 2015
To calculate the five year Impact Factor, citations are counted in 2014 to the previous five years and divided by the source items published in the previous five years.
© Journal Citation Reports 2015, Published by Thomson Reuters
Progress in Aerospace Sciences is an international review journal designed to be of broad interest and use to all those concerned with research in aerospace sciences and their applications in research establishments, industry and universities. The journal is devoted primarily to the publication of specially commissioned review articles designed to bring together under one cover current advances in the ever-broadening field of aerospace sciences. No artificial limits are imposed on the length of papers and authors are encouraged to provide specialist readers with an orderly and concise summary of recent work, including sufficient detail for more general aerospace readers to be informed of recent developments in fields other than their own.
The coverage of the journal includes timely reviews in aeronautics and astronautics, especially in important aerospace areas such as aero- and gas dynamics, aero-and space structures, flight mechanics of air and space vehicles, materials, vibrations, aeroelasticity, acoustics, aero- and space propulsion, avionics, and occasionally some related areas as well, such as wind engineering and hydrodynamics. "While the emphasis is on reviews of current developments, papers providing historical perspectives on important past developments and their pioneers are also welcome. Occasionally, the journal also publishes reviews of new books on aerospace topics."