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An Assessment of Precision Time and Time Interval Science and Technology 3 State of PTTI Research and Infrastructure HEALTH OF THE BASIC RESEARCH BASE Historically, research in areas such as atomic and molecular physics, quantum optics, and solid-state physics, as well as in fields of technology such as photonics and material sciences, has played a key role in advancing the state of the art in PTTI. In particular, the tie between fundamental research in atomic, molecular, and optical (AMO) physics and advances in both state-of-the-art timekeeping and eventual performance improvement in what might be termed commercial-quality devices has been demonstrated over decades and is anticipated to continue for the foreseeable future. Domestically, support for these basic investigations is provided by government organizations like NSF, DOE, NASA, DOD, and the Department of Commerce (NIST), while counterpart foreign organizations worldwide nurture similar studies. The Navy’s role in promoting AMO physics basic research is as a highly targeted yet not dominant source of funding. For example, in FY 01, NSF spending on AMO physics1 was approximately $8 million compared with ONR core expenditures of approximately $2.8 million on both its Atomic and Molecular Physics program and its Lasers and Electro-optics program and NASA expenditures of about $13 million on AMO and clock-related research in its Fundamental Physics program. Although proportionately a smaller contributor in FY 02 to the overall area of AMO physics research, Navy resources, provided through ONR, have paid excellent dividends by enabling advances of great relevance to PTTI, including investigations into the cooling and trapping of atoms, the development of atomic fountain frequency standards, and, more recently, Bose-Einstein condensation. Navy 6.1 support of basic research is significant for advancing the cutting edge of knowledge, as the prior successes of such research have shown. But more importantly for the Navy, these funds are highly leveraged through their judicious application to aspects of AMO physics that can be anticipated to have relevance to PTTI and other areas of Navy interest. 1 Information ollected at the National Science Foundation Web site, <https://www.fastlane.nsf.gov/a6/A6QueryPgm.htm>.
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An Assessment of Precision Time and Time Interval Science and Technology TABLE 3.1 ONR Funding for 6.1 and 6.2 Support of PTTI (million dollars) Year Atomic and Molecular Physics Meteorology and Oceanography Navigation Program Total 6.1 funding 1990 2.5 2.5 2002 2.0 2.0 6.2 funding 1990 1.6 1995 1.6 1.6 1999 1.3 1.3 2001 1.0 0.7 1.7 2002 0.3 1.0 1.3 NOTE: These numbers are the approximate dollars spent from each program in PTTI; PTTI does not have its own program budget, and ONR was able to provide only estimates of the amount of these programs that was directed toward programs that could be characterized as PTTI. Over the last 5 years, however, ONR funding to AMO physics investigations has not been stable. There has been a monotonic decrease in this support in then-year dollars, which becomes even greater when translated into constant dollars (see Table 3.1). This is telling, particularly because overall Navy 6.1 funding increased during those years, even in constant dollars.2 Should this decrease in support continue, the productivity of the program would continue to decline. Because fundamental research entails a long-term investment, the impact of this reduction would not be immediately apparent; over time, however, its effects will be felt in the slowed progress of PTTI-related science and, probably more important, in a smaller pool of scientifically trained personnel who can meet military needs in the field. Given the importance of PTTI to Navy and DOD warfighting capabilities and the unique role the Navy plays in PTTI for all of DOD, the committee believes it is shortsighted to reduce the Navy’s support of the basic research that has for so long led to advances in the field, improved PTTI performance, and supplied a cadre of technically knowledgeable individuals to satisfy the PTTI needs of Navy and DOD programs. Only if the Navy 6.1 AMO physics research program maintains a close relationship with the research and development community can it support long-range research, foster the discovery of technologies, and nurture the next generations of researchers for the future Navy and Marine Corps. At present, ONR funds nearly 30 projects in AMO physics. The supported projects are well attuned to Navy mission goals, with many clearly relevant to the state of the art of PTTI. By their very nature, though, fundamental investigations proceed over many years. Training at the Ph.D. level often requires more than 5 years of graduate study, and particular projects may extend over multiple generations of graduate students before coming to full fruition. With this in mind, the committee believes that stable, multiyear funding of the research programs should be given the highest priority, including stability of the research funding overall and stability of funding to specific researchers. Ultimately, stable funding will ensure the greatest return on the Navy investment in basic research related to PTTI. 2 Information btained from the American Institute of Physics Web site, <http://www.aip.org/enews/fyi/>.
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An Assessment of Precision Time and Time Interval Science and Technology TABLE 3.2 Approximate Worldwide Annual Market for PTTI Devices Technology Units per Year (approximate) Typical Unit Price ($) Worldwide Market, ($/year) (approximate) Quartz crystal 2 × 109 1 (0.1 to 3,000) 1.2 billion Atomic frequency standards Hydrogen maser 10 200,000 2 million Cesium beam 500 50,000 25 million Rubidium cell 50,000 2,000 100 million HEALTH OF THE APPLIED RESEARCH BASE Industrial Base Although there is a significant industrial base in the United States for PTTI technology, with well over 100 companies manufacturing and/or selling time- and frequency-related products, most of it focuses on relatively low-performance commercial applications. Table 3.2 lists the approximate worldwide market for PTTI devices. Because of performance or ruggedness requirements, most commercial products are not suitable for military or space applications. Though a company with a significant commercial base is theoretically well placed to move into military or space products, it would take a number of years and a significant investment of resources for a company producing products for the civilian market to develop and produce a suitable military product. Companies that have no experience in building high-precision frequency products but decide to enter the field will probably find entry to be considerably more difficult than they had anticipated. Presentations3 to this committee by industrial suppliers of PTTI products indicate that there is little incentive for such suppliers to make the sustained investment necessary to produce defense-specific PTTI products, as the defense market is historically too small and inconsistent compared with the civilian market. The capacity of U.S. industry to produce space-qualified atomic frequency standards and high-precision quartz oscillators is extremely limited. There are only four manufacturers capable of producing space-qualified atomic frequency standards (Datum, Frequency Electronics, PerkinElmer (formerly EG&G), and Kernco, Inc.). It is possible that this list could shrink to only one or two companies. Presently only one company (Datum) makes hydrogen masers, and these are not space qualified. The best high-performance quartz oscillators are now made in Europe. The market for all these high-performance products is very small and inconsistent. In general, the lack of sustained government support and stiff competition from overseas has resulted in relatively little U.S. industrial research and development in high-performance standards. Inconsistent funding has also made it difficult for companies to train and maintain a skilled engineering staff. DOD Support of Applied PTTI Investigations The development of PTTI products meeting military requirements has come almost exclusively as a result of DOD support. Because of PTTI’s critical role in providing enhanced operational capabilities, 3 Michael R. Garvey, Datum Corp., briefing to the committee on December 18, 2001; Martin Bloch, Frequency Electronics, Inc., briefing to the committee on March 26, 2002.
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An Assessment of Precision Time and Time Interval Science and Technology the importance to the Navy and the entire DOD of supporting their development cannot be overestimated. There are numerous past and current examples of PTTI-related investigations producing capabilities of operational value to the military. The microcomputer-compensated crystal oscillator (MCXO), for example, is attributable entirely to Army 6.2 investment. This device produces frequency stabilities and accuracies rivaling oven-controlled crystal oscillators while requiring only a small fraction of the operating power, and it is finding use in applications as diverse as navigational buoys and GPS receivers. Army applied studies have also developed many processing techniques that are widely used in the manufacture of precision quartz resonators, such as UV-ozone cleaning, chemical polishing, and polyimide bonding. Programs executed by NRL in support of GPS have made major contributions to advancing the state of the art of atomic clocks for space applications. The development of a fountain clock capability at USNO is also serving to train scientists in the operation of these rather complicated standards, which someday may be the primary contributors to the DOD Master Clock. ONR 6.2 is supporting the development of coherent population-trapping frequency standards and the double-bulb rubidium maser, both of which are aimed at greatly reducing clock size for ultimate use in tactical devices. DARPA has initiated a program to develop a chip-scale atomic clock whose precision would be intermediate between that of current quartz crystals and large-scale atomic clocks. While these DOD programs, taken together, represent a large amount of funding for PTTI research, coordination between them is lacking. Very little work was presented to the committee in the area of synchronization and timing dissemination technology. Programs in satellite timing modems have ended, and inadequate resources are being spent on developing optical synchronization techniques, precision timing aspects of optical-to-electrical and electrical-to-optical conversion, improved PTTI metrology, frequency synthesis, methods for embedding timing in existing communications systems (e.g., LINK-16), methods for synchronizing and syntonizing satellites, methods for overcoming ionospheric and tropospheric transmission uncertainties, and other problems limiting the ability of remote users to communicate time and frequency. Synchronization and global time dissemination, which are important for achieving military applications of PTTI, do not appear to be receiving appropriate attention. Quartz crystal oscillators, key components of the majority of atomic frequency standards and important time and frequency control devices in their own right, are not receiving Navy R&D funding. While there is Army support in this area, the committee finds aggregate support for crystal technology inadequate and interservice coordination lacking. The desire to reduce the size of atomic frequency standards is putting greater emphasis on specific aspects of device design. For example, as the cells that store the atomic species upon which the devices are based become smaller, collisions between these species and the walls of their storage containers become more frequent and more important to overall performance. Advances in small-scale devices require an understanding of these collisional interactions and the development of mitigating techniques such as wall coatings. Progress in this and similar areas requires research in fields beyond AMO physics, such as material sciences and chemistry. Such research is lacking at both the fundamental level and, particularly, the applied level. Over the last several years, aggregate ONR funding for PTTI applied research has fluctuated between $1.3 million and $1.7 million, with FY 02 funding at $1.3 million (see Table 3.1). These fluctuations hurt continuity in development programs. Moreover, they occurred during a period of continuing growth in Navy 6.2/6.3 allocations, raising questions about the priority the Navy gives PTTI investigations. Perhaps the greatest weakness in the support for applied PTTI studies is the lack of a true funding focus. The present approach to support, extracting funds from the meteorology and
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An Assessment of Precision Time and Time Interval Science and Technology oceanography and navigation programs rather than funding a PTTI-specific program, does not place the appropriate emphasis on PTTI studies. The resulting variability in support does not guarantee the continuity of effort that would maximize the probability of project success. A plan is needed for inserting PTTI developments into defense applications. Simply increasing the funding for PTTI science and technology will not ensure improved performance for government users. There are several examples of situations in which large increases in funding did not result in the desired capability. For example, the Navy spent approximately $23 million in the 1970s and 1980s to develop flight-qualified hydrogen maser technology that would support the perceived need for 180-day satellite autonomy. The window of opportunity (GPS Block I) and the need both passed before success could be achieved, and the resulting technology has found no other military application. As another example, the Navy invested in development of alternative vendors for GPS flight clocks. EG&G and Kernco were supported for development of rubidium and cesium clocks, respectively. The cesium clock technology developed by Kernco was not used in GPS IIR despite its superior long-term on-orbit performance, because of technical problems with the large vendor chosen to manufacture the clock. These examples illustrate the importance of developing an effective PTTI insertion plan for the transitioning of research developments into operational capabilities. HEALTH OF THE RELEVANT EDUCATIONAL BASE There is a significant amount of on-the-job training required for all persons entering the precision time and frequency fields. The design and manufacture of atomic frequency standards (clocks) and other precision frequency standards, including quartz oscillators, must be addressed using a systems approach. That is, a frequency standard must be thought of not just as an electronic circuit (thermal and flicker noises, power levels, etc.), but also as a thermal system (static and dynamic sensitivities) and a mechanical system (vibration, static stress, stress relaxation, etc.). Its material characteristics (packaging, aging, wall coatings, etc.) and sensitivity to environmental parameters (temperature, humidity, pressure, acoustics, vibration, electric and magnetic fields, etc.) must also be taken into consideration, and, for practical devices, their cost, size, and power consumption. Nearly every factor has a potential impact on frequency when designing a product that has a stability or accuracy at levels approaching 1 × 10−15 or beyond—relativistic effects become everyday realities, and an act as simple as soldering the lead of a transistor to a circuit board generates a change in the magnetic field that affects the atomic transition frequency, for example. Thus, extensive experience is needed to develop the unique and broad set of skills for understanding the many parameters that are crucial to a successful precision frequency standard. Very few U.S. institutions train students specifically in clocks or precision frequency sources. Other countries, such as Australia, China, Finland, France, Germany, and Russia, train students specifically in precision frequency control and timing. In the United States a number of groups train students in atomic physics and associated precision measurement, and these students can move relatively easily into work on atomic clocks. Table 3.3 names 13 universities in the United States currently receiving PTTI-related funding from ONR. Many of the engineers and scientists now working on atomic clocks came from these schools. Regardless of their university training, virtually all new industry and government hires in the United States must be trained by their employers in PTTI technology. Given the level of sophistication this work involves, it typically takes 5 to 10 years for a person to become fully productive. A number of national laboratories or government-supported institutions train new scientists and engineers in atomic clock technology. Over the last decade the Time and Frequency Division of NIST, in conjunction with the University of Colorado, provided some level of training to more than 30
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An Assessment of Precision Time and Time Interval Science and Technology TABLE 3.3 Universities in the United States Receiving ONR 6.1 Funding in Areas Broadly Related to PTTI University Research Being Funded California Institute of Technology Information dynamics in open quantum systems Florida International University Atom optics with dark hollow beams Massachusetts Institute of Technology Studies of Bose-Einstein condensation; optical metrology with cold trapped hydrogen; atom interferometry Princeton University Optimal control of chemical reactivity in the strong field regime Rice University Quantum degenerate gas of fermionic atoms; creation and manipulation of quantum degenerate atomic strontium Stanford University Studies of electromagnetically induced transparency and its relation to nonlinear optics State University of New York, Stony Brook Cooling and trapping of neutral atoms University of Arizona Quantum dynamics of small atomic Bose-Einstein condensates; nonlinear manipulation and control of matter waves University of Colorado Bose-Einstein condensation and optical traps; ultracold gas of fermionic atoms; fiber atom optics University of Oklahoma Study of Bose-Einstein condensates using perturbation theory University of New Mexico Quantum logic with neutral atoms in traps; quantum nonlocality and entanglement University of Rochester Quantum degenerate atomic mixture vapors Wayne State University Optimal control of chemical reactivity in the strong field regime undergraduate and Ph.D. students and 40 postdoctoral students. In the same time frame, JPL, in conjunction with the University of Southern California and the University of California at Riverside, supported more than 20 undergraduate students, approximately 5 doctoral students, and 10 to 15 postdoctoral students. Other institutions that have supported students or postdocs are the Harvard-Smithsonian Astrophysical Observatory, NRL, USNO, and the Aerospace Corporation. The situation is much worse for quartz resonators and oscillators. A few programs, such as one at the University of Central Florida, study acoustoelectronic technology. There is also some ongoing research on resonator characteristics at Rutgers University and Rensselaer Polytechnic Institute. However, there is no training in precision quartz oscillators at U.S. universities. STANDING OF THE UNITED STATES IN INTERNATIONAL PTTI RESEARCH To discern the trends in PTTI technology in U.S. institutions, and also to compare them with those in institutions outside the United States, presentations at PTTI Systems and Applications Meetings4 and papers published in the Proceedings of the IEEE International Frequency Control Symposium (IEEE-IFCS) were surveyed. (These are the leading symposia for PTTI technology.) The results of the surveys are summarized in Tables 3.4 and 3.5. Table 3.4 compares U.S. and foreign contributions. The PTTI symposia are held in the United States and are sponsored by the USNO, NRL, NASA-JPL, the Air Force Office of Scientific Research, the Defense Information Systems Agency, the Army Research Office, and the Coast Guard Navigation Center. An average of 43 percent of the presentations came from abroad between 1999 and 2001. By comparison, early PTTI meetings in the 1970s were dominated by U.S. contributions. Table 3.5 lists the affiliations of authors (industry, university, national laboratories, military and military laboratories, or collaborations between these groups) of presentations from the United States 4 Detailed information and abstracts can be obtained at <http://tycho.usno.navy.mil/ptti.htm>.
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An Assessment of Precision Time and Time Interval Science and Technology TABLE 3.4 Origin of Papers Presented at PTTI Systems and Applications Meetings Year U.S. Papers Foreign Papers U.S. and Foreign Collaboration Total Papers 1999 31 (46 percent) 32 (48 percent) 4 (6 percent) 67 2000 30 (58 percent) 19 (37 percent) 3 (6 percent) 52 2001 37 (59 percent) 23 (37 percent) 3 (5 percent) 63 TABLE 3.5 Affiliation of Authors of Papers Presented at PTTI Systems and Applications Meetings Year Industry National Laboratoriesa Universities Military and Military Laboratoriesb Collaboration Between Industry, Laboratories, and Universities Total Papers 1999 11 (16 percent) 4 (6 percent) 0 (0 percent) 10 (15 percent) 10 (15 percent) 35 2000 8 (15 percent) 5 (10 percent) 0 (0 percent) 12 (23 percent) 8 (23 percent) 33 2001 12 (19 percent) 7 (11 percent) 3 (5 percent) 14 (22 percent) 4 (6 percent) 40 NOTE: Data include only authors of papers from U.S. sources or from U.S.-foreign collaborations. aNational laboratories include NIST, JPL, and LLNL. bMilitary and military laboratories include USNO, NRL, USAF, DOD, and DOT. and from U.S. and foreign collaborations. Surprisingly, only 3 of 108 presentations are affiliated solely with U.S. universities. One-third of the papers came from the military and military laboratories. Box 3.1 lists the U.S. presenters. Box 3.2, which lists the foreign contributors for the symposia held in 1999 and 2000, illustrates the international breadth of PTTI research. Contributions were made by 22 countries. It should particularly be noted that significant contributions have been made in France to cesium fountain clocks and quartz resonator technology. The results for the IEEE-IFCS symposia are summarized in Table 3.6. The top half of the table shows the average number of papers published in 1991 and 1992. The bottom half of the table shows the same information averaged over 2001 and 2002, a decade later. The papers are divided into acoustic technology (quartz oscillators, quartz resonator design or manufacture, acoustic materials (not just quartz), filters, surface acoustic wave devices, acoustic sensors, etc.) and nonacoustic technologies (atomic frequency standards, time transfer, microwave oscillators, synthesizers, phase noise characterization, stability analysis, etc.). The papers are also broken down into origin (from U.S. institutions and from non-U.S. institutions according to lead author). The institutions are categorized as universities, government laboratories, and industrial laboratories. One important observation from these data is that the total number of papers has gone up by 43 percent over the last 10 years. About half of the increase came from acoustic sensor papers, which increased from one or two a year in 1991 and 1992 to about 20 each year in 2001 and 2002. The acoustic papers have no direct relation to PTTI technology. Also, three or four manufacturing technology papers have been added each year since the Piezoelectric Devices Conference and the IEEE-IFCS merged in 2000. Though the total number of papers has increased, the number of contributions from U.S. institutions has decreased by about 15 percent. This is in contrast to a 133 percent increase in papers from non-
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An Assessment of Precision Time and Time Interval Science and Technology BOX 3.1 U.S. Participants at the 1999 and 2000 PTTI Symposia Aerospace Corporation, Los Angeles, Calif. Agilent Laboratories, Palo Alto, Calif. Agilent Technologies, Santa Clara, Calif. Antoine Enterprises, Washington, D.C. Bellaire Designs, Broomfield, Colo. Boeing Space and Communication Services, Schriever Air Force Base, Colo. California State University, Fullerton Datum, Inc., Beverly, Mass. Department of Transportation, Washington, D.C. FAA/ISI, Vienna, Va. Highland Technology, San Francisco, Calif. Hughes Space and Communications Company, Los Angeles, Calif. Innovative Concepts Inc., McLean, Va. Innovative Solutions International, Vienna, Va. Jet Propulsion Laboratory, Pasadena, Calif. Lawrence Livermore National Laboratory, Livermore, Calif. National Institute of Standards and Technology, Boulder, Colo. Naval Research Laboratory, Washington, D.C. Navward Systems, Dallas, Tex. Odetics, Inc., Anaheim, Calif. Pacific-Sierra Research Corporation, San Diego, Calif. Raytheon Systems Company, Fullerton, Calif. Science Applications International Corporation (SAIC), Torrance, Calif. SFA, Inc., Washington, D.C. Space and Naval Warfare Systems Center, San Diego, Calif. Timing Solutions Corporation, Boulder, Colo. TrueTime Inc., Santa Rosa, Calif. TRW Space and Electronics Group, Redondo Beach, Calif. U.S. Air Force, GPS Joint Program Office, Los Angeles Air Force Base, Calif. U.S. Air Force, Schriever Air Force Base, Colo. U.S. Naval Observatory, Alternate Master Clock, Schriever Air Force Base, Colo. U.S. Naval Observatory, Washington, D.C. U.S. Naval Sea System Command, Washington, D.C. University of Colorado, Boulder, Colo. University of Delaware, Newark Welkin/CSC, Chantilly, Va. Zeta Associates, Fairfax, Va. Zyfer, Inc., Anaheim, Calif. U.S. institutions. The U.S.-based contributions have gone from 61 percent of the total papers to 37 percent. Changes in some specific categories are particularly revealing. The contributions from U.S. government laboratories and from U.S. industry in the acoustics area, though not large in 1991 and 1992, dropped significantly by 2001 and 2002. This is in stark comparison to non-U.S. contributions in the same area. U.S. government laboratory contributions in the nonacoustic areas have not changed much,
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An Assessment of Precision Time and Time Interval Science and Technology BOX 3.2 Foreign Participants at the 1999 and 2000 PTTI Symposia Australia CSIRO National Measurement Laboratory, Sydney National Measurement Laboratory Austria Space Research Institute, Graz Technical University of Graz Technische Univerität Wien, Vienna Belgium Royal Observatory of Belgium, Brussels Canada Marconi Canada, St-Laurent National Research Council, Ottawa NovAtel, Inc., Calgary University of Calgary Université de Montréal China Shaanxi Astronomical Observatory Denmark The FreeBSD Project, Slagelse France Bureau International des Poids et Mesures, Sèvres Centre National d’Etudes Spatiales, Toulouse CEPE, Argenteuil Observatoire de Besançon Germany DLR, Institut für Hochfrequenztechnik, Oberpfaffenhofen Physikalisch-Technische Bundesanstalt, Braunschweig TimeTech GmbH, Stuttgart India Accord Software and Systems Private Limited, Bangalore Italy Istituto Elettrotecnico Nazionale Galileo Ferraris, Turin Politecnico di Torino, Turin Japan Communications Research Laboratory National Research Center of Meteorology Tskuba Space Center, National Space Development Agency Korea Access Network Research Laboratory, Korea Telcom, Seoul Korea Telcom Research and Development Group, Seoul Mexico Guanajuato University, Salamanca Netherlands European Space Agency, ESTEC Poland Astrogeodynamical Observatory, Borowiec Russia Institute of Electronic Measurements KVARZ, Nizhny Novgorod Institute of Metrology for Time and Space, GP VNIFTRI, Mendeleevo Singapore Singapore Productivity and Standards Board South Africa National Metrology Laboratory, Pretoria Spain Real Istituto y Observatorio de la Armada, San Fernando Switzerland Astronomical Institute of the University of Bern Centre Suisse d’Electronique et de Microtechnique (CSEM) SA, Zurich Swiss Federal Office of Metrology, Wabern Temex Neuchâtel Time SA Taiwan Chunghwa Telecom National Taiwan University, Taipei Telecommunication Laboratories, Yang-Mei Ukraine Sichron Center, Kharkiv United Kingdom National Physical Laboratory, Teddington Quartzlock (UK) Ltd., Totnes
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An Assessment of Precision Time and Time Interval Science and Technology TABLE 3.6 Papers Published in Proceedings of the IEEE International Frequency Control Symposium, by Origin (United States versus non-United States) Total United States Other Countries Average of 1991/1992 All papers 101 62 (61) 39 (39) Acoustics papers 56 (55) 29 (29) 27 (27) Univ. Lab. Ind. Univ. Lab. Ind. Univ. Lab. Ind. 15 (15) 21 (21) 20 (20) 7 (7) 10 (10) 12 (12) 8 (8) 11 (11) 8 (8) Nonacoustics papers 45 (45) 33 (33) 12 (12) Univ. Lab. Ind. Univ. Lab. Ind. Univ. Lab. Ind. 7 (7) 24 (24) 14 (14) 3 (3) 18 (18) 12 (12) 3 (3) 6 (6) 3 (3) Average of 2001/2002 All papers 144 53 (37) 91 (63) Acoustics papers 95 (66) 28 (19) 67 (47) Univ. Lab. Ind. Univ. Lab. Ind. Univ. Lab. Ind. 47 (33) 18 (22) 30 (21) 14 (10) 5 (3) 9 (6) 32 (22) 13 (9) 22 (15) Nonacoustics papers 49 (34) 25 (17) 24 (17) Univ. Lab. Ind. Univ. Lab. Ind. Univ. Lab. Ind. 15 (10) 29 (20) 5 (4) 3 (2) 19 (13) 3 (2) 12 (8) 10 (7) 2 (1) NOTE: Univ., universities; Lab., government laboratories; Ind., industrial laboratories. Information estimated from the advance program for 2002. Numbers in parentheses are percentages. but U.S. industry papers decreased dramatically. Also note the large number of papers from non-U.S. universities in 2001-2002. It should be pointed out, however, that most U.S. university work in atomic physics gets presented at physics conferences rather than at the IEEE-IFCS. The increase in U.S. university contributions in acoustics is largely attributable to sensor papers. Table 3.7 breaks down U.S. contributions and those of other countries at the IEEE-IFCS conference. The decrease in U.S. contributions is dramatic, and the 1999 conference—which was held in Europe in conjunction with the European Frequency and Time Forum—indicates the magnitude of foreign contributions. The United States lags behind France, Japan, and other countries in supporting university research in PTTI applications. A single university in France, the Ecole Nationale Supérieure de Mécanique et des Microtechniques, in Besançon, has more researchers working on quartz crystal devices than the United States. (As part of its national effort aimed at making it the world leader in frequency control, France has made major investments in both university and industrial research.)
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An Assessment of Precision Time and Time Interval Science and Technology TABLE 3.7 Papers by Country of Origin for IEEE-IFCS Conferences in Selected Years Conference Location Year United States Germany United Kingdom France China Japan Russia/ USSR Other Joint ForeignForeign Joint U.S.Foreign Unidentified Total Papers Percent U.S. Authors Atlantic City 1975 43 6 5 6 60 71.7 Philadelphia 1980 40 1 10 9 2 8 70 57.1 Philadelphia 1985 52 1 4 8 2 11 0 9 1 2 90 60 Baltimore 1990 52 1 3 5 0 8 0 7 1 3 80 68.8 Los Angeles 1991 57 1 0 4 0 11 7 8 1 3 92 65.2 Hershey, Pa. 1992 60 3 0 8 2 4 13 11 2 7 110 60.9 Salt Lake City 1993 54 1 1 10 4 6 16 12 2 7 113 54 Boston 1994 56 2 0 9 3 10 17 19 0 2 118 49.2 San Francisco 1995 59 0 2 10 2 12 20 12 2 2 121 50.4 Honolulu 1996 80 4 0 10 6 33 10 22 2 5 172 49.4 Orlando 1997 61 5 2 13 10 19 10 17 7 6 150 44.7 Pasadena 1998 72 5 4 9 2 20 11 11 8 9 151 53.6 Besançon 1999 57 14 9 48 9 29 25 61 24 15 291 24.7 Kansas City 2000 52 4 3 10 4 18 12 8 5 6 122 47.5 Seattle 2001 49 9 2 14 9 21 12 16 6 4 142 37.3 NOTE: In 1999, there was a joint meeting of the European Frequency and Time Forum and IFCS.
Representative terms from entire chapter: