4.1. Word Cloud Visualization

A word cloud is a beautiful informative image that communicates much in a single glance. Tagcrowd specializes in making word clouds easy to read, analyze, and compare for a variety of useful purposes. It was created by David Steinbock and is a handy website that allows anyone to create a tag cloud from a file or pasted text (3 MB of data). To visualize the hot topics in Indian tribology research, the word cloud online tool Tagcrowd was used. The controls allow you to add a numerical frequency display, group similar words, and turn off common word filters. To generate a word cloud, the following steps (Zhang, Huang, & Li, 2011) are followed:

5.1. Share of Top Ten Countries

The global publication share of the top ten countries in tribology research varies from 2.13% to 26.31% during the period 2001–2012 (Table 1). The top ten countries together produced 68% of world tribology research output. China tops the list with a share of 26.31% followed by the USA with 16.19% and Japan with 10.27%. These top three countries together produced 53% of world publications. India ranked seventh among the top ten most productive countries with a global publication share of 3.83%.

5.2. Indian Publication Output and its Citation Impact

India contributed 1,293 papers to world tribology research during the period 2001–2012 with an average number of papers per year of 108 (Table 2). Cumulative publications have increased from 227 in 2001–2006 to 1066 in 2007–2012 with a growth rate of 369%. A total of 7,817 citations have been received by these papers from its time of publication up to April 15, 2013. Of 1,293 papers, 863 papers received one or more citations (ranging from 1 to 552) from their publication. Citations per paper were 6.05 during the study period, which has decreased from 12.74 in 2001–2006 to 4.62 in 2007–2012.

Table 1.

Research Output and Share of Top Ten Countries in Tribology 2001-2012

Table 2.

Annual Output and Citation Impact of Indian Tribology

Fig. 1

Linear Model of Papers from 2001–2012

The annual number of papers in tribology research contributed by Indian scientists increased from 21 in 2001 to 166 in 2012 with a peak of 285 in 2010. The coefficient of determination of number of publications is found to be R² = 0.7276 which indicates that the literature was expanding at a considerable growth rate (Fig. 1). The linear best fit was found to be y = 21.913x–43860 where y is number of papers and x is the predicting year. With this, the predicted number of papers is 339 for the year 2017 which is twice that in 2012.

5.3. International Collaborative Papers

India published 17.40% of its total papers with international collaboration during the period 2001–2012 which has increased from 12.33% in 2001–2006 to 18.48% in 2007–2012 (Table 3).

Table 3.

Share of International Collaborative Papers

Major international partner countries are listed in Table 4 and India collaborated with 34 countries during the study period. There were 256 international links in the 225 international collaborative papers, and the internationalization index is 19.80 (=100 x number of international links / total number of papers by India) (Frame & Carpenter, 1979) for tribology research contributed by Indian researchers / scientists. Among the partner countries, the USA had most of the links with 81. Five G7 countries are listed among major partner countries which indicate that India has more frequent partnerships with scientists from G7 countries.

Table 4.

Major Partner Countries

*Since some papers (#28) have international partners from more than one country, this number exceeds the total of international collaborative papers (225).

5.4. No. of Countries by Line and Citation Impact

India published papers with a maximum of three countries during the period 2001–2012 (Table 5). Citation impact of papers with three or more countries received the highest score with 8.33 followed by national output with 6.35. Papers with three countries registered a lowest citation impact of 3.04.

Table 5.

Collaboration Type and its Impact

5.5. Prolific Indian Authors in Tribology Research (2001–2012)

Authors contributing more than 0.5% of the country’s output during 2001–2012 are considered prolific authors and listed in Table 6. Among the 17 most productive authors, 7 authors are from IIT’s and 3 from IISc. B. Basu of IIT Kanpur was the most productive author with 46 papers (3.56%) followed by J. Bijwe of IIT Delhi and S.V. Kailas of IISc. A.K. Agarwal of IIT Kanpur had the highest CPP of 63.89 followed by G. Sundararajan of IARCPMNM Hyderabad (37.1) and D.K. Dwivedi of IIT Roorkee (12.5). The prolific authors had h-index in range from 3.97 to 33.24. The author A.K. Agarwal had the highest h-index value of 33.24 while B.K. Prasad had the lowest at 3.97.

Table 6.

Prolific Authors and their Citation Impact

5.6. Prolific Indian Institutes in Tribology Research (2001–2012)

Institutes contributing more than 1% of the country’s output during 2001–2012 are considered prolific institutes and listed in Table 7. These 17 prolific institutes contributed 688 publications (53%) of the country’s output with a range of 14 and 93 papers. Papers contributed by these prolific institutes received 5,437 citations (~ 70%) from their time of publication of a total 7,817 citations. The top five institutes for production (IISc, IIT Delhi, IIT Kanpur, IIT Madras, and Anna University) contributed 391 papers accounting for 30% of the country’s output. The CPP of these prolific institutes varies from 1.19 to 29. Among the prolific institutes, the International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad received the highest CPP of 29 followed by IIT Kanpur (15.17) and IIT Delhi (8.72). Only two universities, namely Anna University and Jadavpur University, are listed among the prolific institutes. Four research institutes are listed among the prolific institutes. IITs and IISc together published 461 (36% of the country’s output) papers related to tribology during 2001–2012 and this suggests that these are the specialized Indian institutes in tribology research. The highest h-index was achieved by IIT Kanpur, followed by International Advanced Research Centre for Powder Metallurgy and New Materials, Hyderabad (h-index = 25.19) and IIT Delhi (h-index = 18.4), while the lowest is by the Indira Gandhi Center for Atomic Research (h-index = 3.57) among the prolific institutes.

Table 7.

Performance of Prolific Institutes

5.7. Most Preferred Journals

The most productive journals published at least 10 papers contributed by Indian authors are listed in Table 8. These top 22 journals together produced 600 papers contributed by Indian authors comprising 46% of the total Indian output. Only 2 journals originated from India (Sadhana and Transactions of the Indian Institute of Metals) and the remaining journals originated from different countries. It indicates that Indian authors prefer to publish their research findings in international journals more than in Indian ones. Wear ranked top with 121 papers in terms of number of papers while this journal ranked third in terms of CPP. Surface and Coatings Technology received the highest CPP with 17.1 while it is ranked fourth in terms of number of papers. Sadhana ranked fifth in terms of CPP while it is ranked 14^th in terms of number of papers.

5.8. Highly Cited Papers

Characteristics of highly cited papers (having >50 citations) of Indian tribology research during the period 2001–2012 are presented in Table 9. 12 papers received 50 or more citations and these 12 papers have been published in 7 different journals. Of these 7 journals, one journal originates from India while others are from international locations. Out of 12 papers, two were contributed by a single author while others have collaborators. Cumulative citations of these 12 papers are 1,498 accounting for 19% of all citations. One paper has been published with international collaboration (Israel) while others have domestic collaboration (India). The top-cited paper is “Biofuels applications as fuels for internal combustion engines,” authored by A.K. Agarwal for Progress in Energy and Combustion Science in the year 2007 which was published as Review Paper. This paper has received 552 citations from its time of publication through April 25, 2013.

Table 8.

Most Preferred Journals

Table 9.

Most Cited Papers

5.9. Analysis of Words in Title

Article titles contain information about the whole paper which can express the authors’ attitude to the readers, and analysis of words in title gives the exact trend of particular research fields (Malarvizhi, Wang, & Ho, 2010; Sun, Wang, & Ho, 2012; Ma, Ho, & Fu, 2011). Fig. 2 provides information about the frequency of single word in titles of research papers contributed by Indian tribologists. Some prepositions such as of, and, the, and or are discarded from the display. Common words like during, analysis, study, performance, investigation, behavior, experiment, tool, characteristics, properties, evaluation, conditions and based were omitted from the analysis. The font size of the text indicates how often the word is used. It can be observed that Composites and Friction are high frequency words followed by Tribology and Wear.

Fig. 2

Word Cloud of Single Words in Title Created through Tagcrowd.com