Detecting seminal research contributions to the development and use ...

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May 17, 2015 - of funding agencies, universities and institutes to research fields. We stress ... in 2015, it is currently the most popular smartphone application in.
Scientometrics (2015) 104:575–580 DOI 10.1007/s11192-015-1598-2

Detecting seminal research contributions to the development and use of the global positioning system by reference publication year spectroscopy Jordan A. Comins1



Thomas W. Hussey1

Received: 7 November 2014 / Published online: 17 May 2015 Ó Akade´miai Kiado´, Budapest, Hungary 2015

Abstract The global positioning system (GPS) represents one of the most compelling success stories of technology transfer from defense laboratories and academia to the private sector. In this short report, we applied a quantitative analysis to identify landmark research contributions to GPS. This technique, reference publication year spectroscopy (RPYS), yielded key insights into early works that allowed for both the development and widespread use of GPS. In addition, using this approach to identify individual contributions of scientific excellence offers an opportunity to credit not only the research investigators, but also their corresponding affiliations and funding sources. Indeed, the findings from our analysis suggest that RPYS might serve as a powerful tool to substantiate the contribution of funding agencies, universities and institutes to research fields. We stress, however, that this method should not stand-alone for such purposes, but should be wedded with the knowledge and experience of subject matter experts. Keywords Scientometrics  Reference publication year spectroscopy  Global positioning system  Science policy  Funding agencies

Introduction The global positioning system (GPS) represents one of the greatest success stories of Department of Defense (DoD) technology being transferred to the private sector. GPS resulted from the enduring efforts of researchers across the panoply of DoD agencies and laboratories, including the Air Force, Army, Navy and Defense Advanced Research Projects Agency (DARPA). Products and applications, such as Google Maps, best capture the achievement of these research and technology transfer efforts—as Google Maps celebrates

& Jordan A. Comins [email protected] 1

Virginia Tech Applied Research Corporation, Arlington, VA 22203, USA

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its 10-year anniversary in 2015, it is currently the most popular smartphone application in the world (Smith 2013). Presently, many of the scientific accomplishments of the DoD research underlying GPS have been documented (Enge and Misra, 1999). Indeed, Bradford Parkinson and Ivan Getting, both of whom received the 2003 National Academy of Engineering Charles Stark Draper Prize, each published detailed accounts on the history of GPS (Getting 1993; Parkinsonet al. 1995). However, many of the accounts of the history of GPS do not emphasize the role that research performed outside of DoD laboratories, particularly in the fields such as signal processing, radio sciences and statistical methods, might have played in the development, modernization, and widespread use of GPS technology. The present paper attempts to provide some insights into high-impact contributions of research beyond DoD labs for GPS’ advance and usage by reference publication year spectroscopy (RPYS). RPYS is a quantitative method in the field of scientometrics that can assist in identifying the historical roots of research fields and topics (Marx et al. 2014). In brief, the method produces a frequency distribution of references cited by a set of publications, where this distribution is sorted by the publication year of these cited references. The resulting functions yield temporal profiles of cited references that, in general, emphasize years where relatively significant findings were published. Thus far, RPYS has been used to great success to evaluate the historical roots of a number of research fields and topics, including graphene, solar cells, the misnomer ‘‘Darwin’s finches’’, iMetrics and the Viterbi algorithm (Leydesdorff et al. 2014; Marx et al. 2014; Marx and Bornmann 2013; Comins and Hussey 2015). In the present report, we employ the RPYS method to discern punctuated peaks of historical impact of extramural research on GPS. We go on to identify those papers underlying these peaks and characterize them by both describing how they pertain to GPS and by asking which funding agencies sponsored their research. Thus, we provide an account of both the scientists and, where possible, the funding sources of the extramural research that contributed to the development and widespread use of GPS. We propose the RPYS could become an indispensable tool for helping funding agencies evaluate the historical value of their research support across a plethora of research subfields and topics.

Method Data was accessed and downloaded from the Thomson Reuters Web of Science (WoS) on November 6, 2014. We began by performing a topic search of the Web of Science Core Collection for GPS. We then filtered these results to only represent scientific articles. This resulted in a total of 8088 articles from 1974 to 2014. We downloaded these results from WoS using the ‘‘Save to Other File Formats’’ button and set our record content to ‘‘Full Record and Cited References’’. Next, we sought to extract the cited references from these 8,088 articles. This was done in two ways to ensure the integrity of our data. For the first method, we used the open source Sci2 tool (Sci2 Team 2009) developed by Indiana University to transform Full ISI records into tables. This resulted in each full record being represented as a single row in a table with ‘‘Cited References’’ represented by a column within this table. The data organized in the cited references column from this procedure contains a | character as a delimiter between different references cited. We used a python script to split our cited references based on this delimiter and generated a new table representing all of the cited

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references. From this process, we were able to effectively isolate 230,061 references and their associated publication year. From this table, we produced a frequency distribution of the references cited and sorted this distribution by the publication year of these cited references. In prior work, such distributions allow one to visualize distinct peaks in cited reference years that are traditionally driven by the publication of a seminal work. To improve our ability to recognize such peaks, we also visualized the absolute deviation of the number of cited references in any given year from the 5-year median number of cited references. Finally, to verify the quality of our procedure, we took a second approach and used a well-documented method for RPYS (the freeware software RPYS.exe) and correlated the results obtained by our procedure and this previously established method (Leydesdorff et al. 2014).

Results Before discussing our main findings, we confirm the validity of our approach to procuring data for RPYS by correlating the number of cited references we obtained between 1900 and 1980 (our years of interest for the forthcoming analysis) with those yielded by established methods (Leydesdorff et al. 2014; Marx et al. 2014; Marx and Bornmann, 2013). We observed a perfect correlation between results obtained via our method and those using RPYS.exe (r2 = 1.0, p \ 0.0001), suggesting the validity of our approach for collecting and filtering RPYS data. Next, we plotted the distribution of cited references between 1900 and 1980, revealing 5 distinct peaks (Fig. 1). These peaks can be accentuated by visualizing the absolute deviation of cited references in any given year from the 5-year median number of cited references (Fig. 1). The peaks corresponded to the years 1953, 1960, 1965, 1972 and 1974, suggesting that important extramural papers for the development and widespread use of GPS might have been published in those years. Papers published in 1953 received a total of 165 citations. The largest share of these citations (N = 63) was attributed to the article, ‘‘The Constants in the Equation for Atmospheric Refractive Index’’ by Ernest K. Smith, Jr. and Stanley Weintraub from the Central Radio Propogation Laboratory in Boulder, Colorado in Proceedings of the Institute of Radio Engineers. This paper by Smith and Weintraub (1953) proposes an improved model of the refractive index in air for RF radiation as a function of altitude, which would be required to know the precise propagation path of an RF signal through the atmosphere

Fig. 1 Distribution of cited references sorted by the reference publication year (1900–1980) is shown in gray columns. The red line shows the absolute deviation of cited references for a given year from the median of a 5-year epoch, accentuating years with an unexpectedly high number of reference publications, often indicating a seminal work

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from a satellite to ground. It also provides a discussion of the source of uncertainty in knowing the path exactly. The next peak occurs in 1960, where 284 references were cited. Of these references, the paper receiving the most citations (N = 52) was ‘‘A New Approach to Linear Filtering and Prediction Problems’’ by Rudolf E. Kalman from the Research Institute for Advanced Study in Baltimore, Maryland in the Journal of Basic Engineering. This paper (Kalman 1960), which was funded by the Air Force Office of Scientific Research (AFOSR), is a seminal result in estimation theory. Referred to as the Kalman filter, this approach operates recursively on streams of noisy input measurements to produce a statistically optimal estimate of the underlying system state that provides more accuracy than any individual measurement of intrinsically noisy data. The implementation of the Kalman filter, and extensions to it, are common practice in navigation, guidance and control systems, which require integrating multiple signals to estimate an object’s position, velocity or attitude. The third, albeit weakest, peak corresponds to 1965. Of the 431 citations to references published in this year, the largest stake for any one paper was only 20. This suggests that the peak here might correspond to a number of papers of slightly higher than average performance being published, and not necessarily one standout publication. Nevertheless, this most cited paper from 1965 was a ‘‘Problem and Solution’’ dialogue. J.L. Farrell and J.C. Stuelpnagel of the Westinghouse Defense and Space Center solved the cited problem, ‘‘A least squares estimate of satellite attitude’’ by Grace Wahba, which was published in SIAM Review. Another article received similar numbers of citations. The publication, ‘‘Maximum likelihood estimates of linear dynamic systems’’ by H. Rauch, F. Tung and C. Striebel in the AIAA Journal, is an extension to the work by Kalman that provides additional smoothing to the data stream. Next, in 1972, 104 out of 956 citations were attributed to the work ‘‘Atmospheric Correction for the Troposphere and Stratosphere in Radio Ranging of Satellites’’ by J. Saastamoinen of the National Research Council of Canada in the Geophysical Monograph Series. This work by Saastamoinen (1972) calculates the correction to satellite signals from baseline (hydrostatic) conditions of the troposphere and stratosphere. It additionally discusses uncertainties in this correction due to deviations from those baseline conditions. Saastamoinen’s corrections, later dubbed the Saastamoinen model, is considered to be amongst, if not, the most reliable for the production of baseline results (Dodo et al. 2013; Opaluwa and Adejare 2013; Satirapod and Chalermwattanachai 2005). Knowledge of the atmospheric effects biasing satellite signals as well as how to correct for them is vital to the success of an accurate positioning system. The final peak observed in our RPYS for GPS occurred in 1974. The book Applied Optimal Estimation edited by Arthur Gelb received a sum of 86 out of 1,026 citations. This text in estimation theory, edited by Gelb, provides a comprehensive review of the methods applicable to analyzing noisy data streams.

Discussion We applied Reference Publication Year Spectroscopy to research articles obtained from a topic search of the Web of Science Core Collection for ‘‘GPS.’’ Our intent was to identify key research contributions for the development and widespread use of GPS. Our findings highlight several pioneering contributions, primarily from quantitative disciplines, that appear essential to the pervasive impact of GPS today.

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In addition to identifying key investigators involved in making these scientific discoveries, we also specified their associated research affiliations and funding agencies. Such details could provide useful information regarding the role of research groups or funding agencies to impactful scientific breakthroughs. It is important not to over-interpret this point; RPYS cannot be relied upon to capture the full spectrum of individuals and organization contributing to the advancement of a given research field. However, in the same way that authors and their seminal works are acknowledged by the outcomes of RPYS, we suggest too that the ‘‘subauthorship’’ collaborators (those noted in the acknowledgment section of the work; Heffner 1981) may also be recognized. Indeed, while information contained in the acknowledgement section of scholarly works remains largely underutilized in bibliometrics, it does provide a veridical indication of the contributions of colleagues and institutions beyond the authors (Cronin and Franks 2006; Cronin 2014; Heffner 1981). Therefore, procedures such as those described in the current report could serve as a useful tool for analysts exploring the contribution of research affiliations and funding agencies on specific research topics. Acknowledgments Effort sponsored in whole or in part by the Air Force Research Laboratory, USAF, under Partnership Intermediary No. FA9550-13-3-0001. The U.S. Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright notation thereon. The authors thank Luke Sebby and two anonymous reviewers for constructive feedback. Conflict of interests JAC works for the non-profit Virginia Tech Applied Research Corporation (VTARC), which supports the Air Force Office of Scientific Research (AFOSR). TWH consults for VT-ARC and is the former Chief Scientist of AFOSR. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the Air Force Research Laboratory.

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