In this section we will discuss the macroscopic trends, on a worldwide basis, of the publications and citations data collected for five time periods from 1980 to 2006 for the field of chemical engineering at large. Appendix 3B lists all the journals that were considered. They were grouped in the following three categories:
journals with broad coverage of chemical engineering research
journals with broad coverage of sciences and engineering disciplines, in which chemical engineers publish
leading journals for each subarea of chemical engineering
The total number of papers published was found by searching the Web of Science (http://portal.isiknowledge.com/portal.cgi) for all publications during the corresponding period, with the requirement that a co-author had a chemical engineering affiliation in the address field. For the United States, a chemical engineering affiliation is a good indicator that a researcher is involved in chemical engineering research. Recent changes in the affiliation of academic researchers from chemical engineering departments to biological engineering or biomedical engineering departments have been taken into account; biological and biomedical engineering departments populated recently by the transfer of chemical engineers were included in the search and the lists were pruned by eliminating the faculty members in these departments who did not hold a Ph.D. in chemical engineering.. However, for non-U.S. researchers with research activities within the scope of chemical engineering as understood in the United States, the corresponding affiliation is not a very good indicator. Many such researchers are affiliated with departments that do not contain “chemical engineering” in their name. Particular attention on select very active universities in Europe and Japan (e.g. ETH-Zurich and Kyoto University, respectively), was given to include the contributions of the non-U.S. researchers who would qualify as chemical engineers, but the numbers of papers by non-U.S. chemical engineering researchers should be viewed as lower bounds.
Analysis of publications and citations by chemical engineers in all three groups of journals has revealed the following trends:
Trend 1: The relative volume of the U.S.-originated journal publications by chemical engineers, as a fraction of the worldwide total, has been halved over the past 20 years.