Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “2011”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15

2011 Presidential Early Career Awards for Scientists and Engineers: the PECASE Awards Ceremony

The winners for 2011 of the DOE PECASE Awards were recognized in a ceremony held August 01, 2012. Dr. Bill Brinkman, Director of the Office of Science introduced the main speaker, DOE Deputy Secretary Daniel B. Poneman. Leaders from across the Department and the fields of energy research and technology presented the 2011 winners. They are: Dr. Stanley Atcitty (SNL); Dr. Jeffrey W. Banks (LLNL); Dr. Amy J. Clarke (LANL); Derek R. Gaston (INL); Dr. Christopher Hirata (California Institute of Technology); Dr. Heileen Hsu-Kim (Duke University); Dr. Thomas Francisco (Jaramillo Stanford University); Dr.Pablo Jarillo-Herrero (MIT); Dr. Peter Mueller (ANL); Dr. Daniel B. Sinars (SNL); Dr. Jesse Thaler (MIT); and Dr. Heather Whitley (LLNL).

99 GENERAL AND MISCELLANEOUS↗

The 2011 Dynamics of Molecular Collisions Conference

The Dynamics of Molecular Collisions Conference focuses on all aspects of molecular collisions--experimental & theoretical studies of elastic, inelastic, & reactive encounters involving atoms, molecules, ions, clusters, & surfaces--as well as half collisions--photodissociation, photo-induced reaction, & photodesorption. The scientific program for the meeting in 2011 included exciting advances in both the core & multidisciplinary forefronts of the study of molecular collision processes. Following the format of the 2009 meeting, we also invited sessions in special topics that involve interfacial dynamics, novel emerging spectroscopies, chemical dynamics in atmospheric, combustion & interstellar environments, as well as a session devoted to theoretical & experimental advances in ultracold molecular samples. Researchers working inside & outside the traditional core topics of the meeting are encouraged to join the conference. We invite contributions of work that seeks understanding of how inter & intra-molecular forces determine the dynamics of the phenomena under study. In addition to invited oral sessions & contributed poster sessions, the scientific program included a formal session consisting of five contributed talks selected from the submitted poster abstracts. The DMC has distinguished itself by having the Herschbach Medal Symposium as part of the meeting format. This tradition of the Herschbach Medal was first started in the 2007 meeting chaired by David Chandler, based on a generous donation of funds & artwork design by Professor Dudley Herschbach himself. There are two such awards made, one for experimental & one for theoretical contributions to the field of Molecular Collision Dynamics, broadly defined. The symposium is always held on the last night of the meeting & has the awardees are asked to deliver an invited lecture on their work. The 2011 Herschbach Medal was dedicated to the contributions of two long standing leaders in Chemical Physics, Professor Yuan T. Lee & Professor George Schatz. Professor Lee’s research has been based on the development & use of advanced chemical kinetics & molecular beams to investigate & manipulate the behavior of fundamental chemical reactions. Lee’s work has been recognized by many awards, including the Nobel Prize for Chemistry in 1986, as well as Sloan Fellow, Dreyfus Scholar, Fellowship in the American Academy of Arts & Sciences, Fellowship in the American Physical Society, Guggenheim Fellow, Member National Academy of Sciences, Member Academia Sinica, E.O. Lawrence Award, Miller Professor, Berkeley, Fairchild Distinguished Scholar, Harrison Howe Award, Peter Debye Award, & the National Medal of Science. Lee also has served as the President of the Academia Sinica in Taiwan (ROC). Professor Schatz’s research group is interested in using theory & computation to describe physical phenomena in a broad range of applications relevant to chemistry, physics, biology & engineering. Among the types of applications that we interested are: optical properties of nanoparticles & nanoparticle assemblies; using theory to model polymer properties; DNA structure, thermodynamics & dynamics; modeling self assembly & nanopatterning; & gas phase reaction dynamics. Among his many awards & distinctions have been appointment as an Alfred P. Sloan Research Fellow, Camille & Henry Dreyfus Teacher-Scholar, the Fresenius Award, Fellow of the American Physical Society, the Max Planck Research Award, Fellowship in the American Association for the Advancement of Science, & election to the International Academy of Quantum Molecular Sciences & the American Academy of Arts & Sciences. Dr Schatz is also lauded for his highly successful work as Editor for the Journal of Physical Chemistry. We requested $10,000 from DOE in support of this meeting. The money was distributed widely among the student & post doctoral fellows & some used to attract the very best scientists in the field. The organizers were committed to encouraging women & minorities as well as encourage the field of Chemical Physics in scientifically developing countries. For example, it has been a tradition of the DMC meeting to offer of order 40 scholarships for students & postdocs to defray registration & travel costs. The benefits of increased graduate student & post doctoral attendance at the meeting cannot be over emphasized. First, these young scientists have the opportunity to present their work by means of the poster session & to a gathering of experts in their field. Secondly the limited size of the meeting allows student & young postdocs to meet & interact directly with experts in their area, to network with their peers at other institutions & become aware of career opportunities. Graduate students & post doctoral fellows are the life blood of our field. Support of their attendance at this & other similar meetings will ensure a continued flow of young talent into many areas of research represented by the DMC meeting & important to DOE.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Olkiluoto 1 and 2 - Plant efficiency improvement and lifetime extension-project (PELE) implemented during outages 2010 and 2011

Teollisuuden Voima Oyj (TVO) is a non-listed public company founded in 1969 to produce electricity for its stakeholders. TVO is the operator of the Olkiluoto nuclear power plant. TVO follows the principle of continuous improvement in the operation and maintenance of the Olkiluoto plant units. The PELE project (Plant Efficiency Improvement and Lifetime Extension), mainly completed during the annual outages in 2010 and 2011, and forms one part of the systematic development of Olkiluoto units. TVO maintains a long-term development program that aims at systematically modernizing the plant unit systems and equipment based on the latest technology. According to the program, the Olkiluoto 1 and Olkiluoto 2 plant units are constantly renovated with the intention of keeping them safe and reliable, The aim of the modernization projects is to improve the safety, reliability, and performance of the plant units. PELE project at Olkiluoto 1 was done in 2010 and at Olkiluoto 2 in 2011. The outage length of Olkiluoto 1 was 26 d 12 h 4 min and Olkiluoto 2 outage length was 28 d 23 h 46 min. (Normal service-outage is about 14 days including refueling and refueling-outage length is about seven days. See figure 1) The PELE project consisted of several single projects collected into one for coordinated project management. Some of the main projects were as follows: - Low pressure turbines: rotor, stator vane, casing and turbine instrumentation replacement. - Replacement of Condenser Cooling Water (later called seawater pumps) pumps - Replacement of inner isolation valves on the main steam lines. - Generator and the generator cooling system replacement. - Low voltage switchgear replacement. This project will continue during future outages. PELE was a success. 100 TVO employees and 1500 subcontractor employees participated in the project. The execution of the PELE projects went extremely well during the outages. The replacement of the low pressure turbines and seawater pumps improved the efficiency of the plant units, and a power increase of nearly 20 MW was achieved at both plant units. PELE wonderfully manifests one of the strategic goals of our company; developing the competence of our in-house personnel by working in projects. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗

2011 Mound Site Groundwater Plume Rebound Exercise and Follow-Up - 13440

The Mound Site facility near Miamisburg, Ohio, opened in 1948 to support early atomic weapons programs. It grew into a research, development, and production facility performing work in support of the U.S. Department of Energy (DOE) weapons and energy programs. The plant was in operation until 1995. During the course of operation, an onsite landfill was created. The landfill was located over a finger of a buried valley aquifer, which is a sole drinking water source for much of the Miami Valley. In the 1980's, volatile organic compounds (VOCs) were discovered in groundwater at the Mound site. The site was placed on the National Priorities List on November 21, 1989. DOE signed a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Federal Facility Agreement with the U.S. Environmental Protection Agency (EPA) and the Ohio Environmental Protection Agency. The agreement became effective in October 1990. The area that included the landfill was designated Operational Unit 1 (OU-1). In 1995, a Record of Decision was signed that called for the installation and operation of a pump and treatment (P and T) system in order to prevent the VOCs in OU-1 groundwater from being captured by the onsite water production wells. In addition to the P and T system, a soil vapor extraction (SVE) system was installed in 1997 to accelerate removal of VOCs from groundwater in the OU-1 area. The SVE system was successful in removing large amounts of VOCs and continued to operate until 2007, when the amount of VOCs removed became minimal. A rebound study was started in February 2003 to determine how the groundwater system and contaminants would respond to shutting down the P and T system. The rebound test was stopped in February 2004 because predetermined VOC threshold concentrations were exceeded down-gradient of the landfill. The P and T and SVE systems were restarted after the termination of the rebound test. In 2006, the remediation of the Mound site was completed and the site was declared to be protective of human health and the environment, as long as the institutional controls are observed. The institutional controls that apply to the OU-1 area include provisions that no soil be allowed to leave the site, no wells be installed for drinking water, and the site may be approved only for industrial use. The onsite landfill with the operating CERCLA remedy remained. However, the Mound Development Corporation lobbied Congress for funds to remediate the remaining onsite landfill to allow for property reuse. In 2007 DOE received funding from Congress to perform non-CERCLA removal actions at OU-1 to excavate the site sanitary landfill. In 2009, DOE received American Recovery and Reinvestment Act funding to complete the project. Excavation of the landfill occurred intermittently from 2006 through 2010 and the majority of the VOC source was removed; however, VOC levels near the P and T system remained greater than the EPA maximum contaminant levels (MCLs). Presently, groundwater is contained using two extraction wells to create a hydraulic barrier to prevent down-gradient migration of VOC-impacted groundwater. Since the primary contamination source has been removed, the feasibility of moving away from containment to a more passive remedy, namely monitored natural attenuation (MNA), is being considered. A second rebound study was started in June 2011. If contaminant and groundwater behavior met specific conditions during the study, MNA would be evaluated and considered as a viable alternative for the groundwater in the OU-1 area. From June through December 2011, the second rebound study evaluated the changes in VOC concentrations in groundwater when the P and T system was not in operation. As the study progressed, elevated concentrations of VOCs that exceeded predetermined trigger values were measured along the down-gradient boundary of the study area, and so the P and T system was restarted. It was determined that a discrete area with VOC concentrations greater than the MCLs was present in groundwater down-gradient of the extraction wells. The source was not identified, but the contamination was thought not to be caused by residually contaminated soil beneath the former landfill. The data collected so far supports the consideration of MNA as a viable alternative to hydraulic containment. Additional investigations are being performed to identify possible sources or pathways of VOCs in groundwater that may be contributing to the elevated VOC levels measured down-gradient of the extraction well system. Data from this additional investigation will be used to determine whether the VOCs detected down-gradient of the hydraulic boundary are the result of residual soil contamination, a previously unknown contribution of VOC-contaminated water entering the groundwater outside the capture zone of the extraction wells, or a pulse of VOC-contaminated groundwater from the OU-1 landfill that occurred during the rebound study. (authors)

54 ENVIRONMENTAL SCIENCES↗

The LLWR's 2011 Environmental Safety Case - 12143

The Low Level Waste Repository (LLWR) is the United Kingdom's principal facility for the disposal of LLW. The LLWR recently submitted an Environmental Safety Case (ESC), which will support applications to regulatory and government authorities to dispose of LLW and to start to install final closure engineering. The ESC is a major submission, with important implications for the future of the LLWR and the United Kingdom's management of LLW. The paper describes the context of the ESC, the ESC, its results and conclusions, and its implementation. The description shows that our ESC is a modern safety case developed as a range of safety arguments concerning our management, scientific and technical understanding, optimisation of the facility, as well as assessment calculations. The LLWR's 2011 ESC is a major submission, with important implications for the future of the LLWR and the United Kingdom's management of LLW. The description given of the scope of the ESC shows that it is a modern safety case developed as a range of safety arguments concerning our management, scientific and technical understanding, optimisation of the facility, as well as assessment calculations. A number of key advances have been made since the previous submission. In particular, the 2011 ESC addresses the criticisms made by the regulator on the previous submission in 2002, including those relating to lack of demonstration of optimisation, high calculated doses and risks compared with guidance levels, treatment of coastal erosion, and treatment of uncertainty. The ESC is being reviewed by the environmental regulator and it is hoped that a new permit for disposal of LLW and installation of closure engineering, along with the appropriate planning permission, will be obtained during 2013. The ESC, including its proposed waste acceptance arrangements, is already being implemented by the LLWR where consistent with our current Permit. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Upgrade and Certification of the Los Alamos National Laboratory SHENC 2011 - 12270

Nondestructive assay measurements of Transuranic (TRU) waste at Los Alamos National Laboratory (LANL) required the addition of a standard waste box (SWB) assay system. A Super High Efficiency Neutron Counter (SHENC) located at Hanford was identified to be relocated to LANL. After careful evaluation of waste streams at LANL, it was determined that the current configuration of the SHENC was not sufficient to quantify certain waste streams. At LANL, there is still a large amount of waste that needs to be retrieved and repackaged within SWB's to meet agreements with the State of New Mexico. Prior to relocating the SHENC, the only assay systems available were High Efficiency Neutron Counters having only a 55-gallon drum capacity. Further analyses indicated that the SHENC system should be capable of quantitative gamma measurements that are to be linked, and combined, with the neutron measurements. The SHENC system was therefore augmented with a new high-resolution gamma spectroscopy system using BE5030 detectors and upgraded gamma electronics. The neutron side of the system was also upgraded with an advanced shift register (JSR-15), an improved Programmable Logic Controller and NDA-2000 software. This report will include calibration of both the neutron and gamma modalities of the SHENC system and how the modality results are combined to produce a single assay result. Preliminary performance results will be discussed based on both mock and real waste measurements. Discussions will also include a complete description of the adjustable parameters as well as the calibration plan, techniques and validations including calibration confirmation based on the Waste Isolation Pilot Plant Waste Acceptance Criteria (WIPP-WAC). The SHENC was successfully upgraded to efficiently measure the complex waste streams at Los Alamos National Laboratory. A new PLC was successfully added to the system for Add-A-Source control. A new shift register was added to the SHENC (JSR-15) which provides more flexibility if replacement is required. The addition of the density based calibration on the gamma modality of the system increases the effectiveness of the SHENC for high alpha-n producing waste. Upgrading the system to new software also helped to standardize the program at Los Alamos. Only one new procedure was initiated for the integration of the SHENC. Add-A-Source measurements were effectively integrated with the system based on the confirmation results and positive results during two Department of Energy Performance Demonstration Program Box Cycles. Total measurement uncertainty estimates were completed for both the gamma modality and the neutron modality of the system. The SHENC was reviewed by both the Department of Energy and the Environmental Protection Agency in 2011. The certification letter for the SHENC was issued on November 16, 2011. With the certification letter issued to the Central Characterization Project the SHENC can perform waste measurements on SWB's at Los Alamos for shipment to WIPP. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Nonproliferation Graduate Fellowship Program Annual Report: Class of 2011

Annual report for the Nonproliferation Graduate Fellowship Program (NGFP), which PNNL administers for the National Nuclear Security Administration (NNSA). Features the Class of 2011. The NGFP is a NNSA program with a mission to cultivate future technical and policy leaders in nonproliferation and international security. Through the NGFP, outstanding graduate students with career interests in nonproliferation are appointed to program offices within the Office of Defense Nuclear Nonproliferation (DNN). During their one-year assignment, Fellows participate in programs designed to detect, prevent, and reverse the proliferation of nuclear weapons.

2012↗

Radionuclide Air Emission Report for 2011

Berkeley Lab operates facilities where radionuclides are produced, handled, stored, and potentially emitted. These facilities are subject to the EPA radioactive air emission regulations in 40 CFR 61, Subpart H. Radionuclides may be emitted from stacks or vents on buildings where radionuclide production or use is authorized or they may be emitted as diffuse sources. In 2011, all Berkeley Lab sources were minor sources of radionuclides (sources resulting in a potential dose of less than 0.1 mrem/yr [0.01 mSv/yr]). These minor sources included about 90 stack sources and one source of diffuse emissions. There were no unplanned airborne radionuclide emissions from Berkeley lab operations. Emissions from minor sources (stacks and diffuse emissions) were measured by sampling or monitoring or were calculated based on quantities used, received for use, or produced during the year. Using measured and calculated emissions, and building-specific and common parameters, Laboratory personnel applied the EPA-approved computer codes, CAP88-PC and COMPLY, to calculate the effective dose equivalent to the maximally exposed individual (MEI).

54 ENVIRONMENTAL SCIENCES↗

Nevada National Security Site Environmental Report 2011

This report was prepared to meet the information needs of the public and the requirements and guidelines of the U.S. Department of Energy (DOE) for annual site environmental reports. It was prepared by National Security Technologies, LLC (NSTec), for the U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office (NNSA/NSO). This and previous years reports, called Annual Site Environmental Reports (ASERs), Nevada Test Site Environmental Reports (NTSERs), and, beginning in 2010, Nevada National Security Site Environmental Reports (NNSSERs), are posted on the NNSA/NSO website at http://www.nv.energy.gov/library/publications/aser.aspx. This NNSSER was prepared to satisfy DOE Order DOE O 231.1B, 'Environment, Safety and Health Reporting.' Its purpose is to (1) report compliance status with environmental standards and requirements, (2) present results of environmental monitoring of radiological and nonradiological effluents, (3) report estimated radiological doses to the public from releases of radioactive material, (4) summarize environmental incidents of noncompliance and actions taken in response to them, (5) describe the NNSA/NSO Environmental Management System and characterize its performance, and (6) highlight significant environmental programs and efforts. This NNSSER summarizes data and compliance status for calendar year 2011 at the Nevada National Security Site (NNSS) (formerly the Nevada Test Site) and its two support facilities, the North Las Vegas Facility (NLVF) and the Remote Sensing Laboratory-Nellis (RSL-Nellis). It also addresses environmental restoration (ER) projects conducted at the Tonopah Test Range (TTR). Through a Memorandum of Agreement, NNSA/NSO is responsible for the oversight of TTR ER projects, and the Sandia Site Office of NNSA (NNSA/SSO) has oversight of all other TTR activities. NNSA/SSO produces the TTR annual environmental report available at http://www.sandia.gov/news/publications/environmental/index.html.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Nevada National Security Site Environmental Report 2011 Attachment A: Site Description

This attachment expands on the general description of the Nevada National Security Site (NNSS) presented in the Introduction to the Nevada National Security Site Environmental Report 2011. Included are subsections that summarize the site's geological, hydrological, climatological, and ecological setting and the cultural resources of the NNSS. The subsections are meant to aid the reader in understanding the complex physical and biological environment of the NNSS. An adequate knowledge of the site's environment is necessary to assess the environmental impacts of new projects, design and implement environmental monitoring activities for current site operations, and assess the impacts of site operations on the public residing in the vicinity of the NNSS. The NNSS environment contributes to several key features of the site that afford protection to the inhabitants of adjacent areas from potential exposure to radioactivity or other contaminants resulting from NNSS operations. These key features include the general remote location of the NNSS, restricted access, extended wind transport times, the great depths to slow-moving groundwater, little or no surface water, and low population density. This attachment complements the annual summary of monitoring program activities and dose assessments presented in the main body of this report.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Geothermal Technologies Program: 2011 Peer Review Report

On June 6-10, 2011, the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy (EERE), Geothermal Technologies Program (GTP or the Program) conducted its annual program peer review in Bethesda, Maryland. In accordance with the EERE Peer Review Guide, the review provides an independent, expert evaluation of the strategic goals and direction of the program and is a forum for feedback and recommendations on future program planning. The purpose of the review was to evaluate DOE-funded projects for their contribution to the mission and goals of the Program and to assess progress made against stated objectives.

15 GEOTHERMAL ENERGY↗

NREL RSF Measured Data 2011

Modern buildings are complex energy systems that must be controlled for energy efficiency. The Research Support Facility (RSF) at the National Renewable Energy Laboratory (NREL) has hundreds of controllers -- computers that communicate with the building's various control systems -- to control the building based on tens of thousands of variables and sensor points. These control strategies were designed for the RSF's systems to efficiently support research activities. Many events that affect energy use cannot be reliably predicted, but certain decisions (such as control strategies) must be made ahead of time. NREL researchers modeled the RSF systems to predict how they might perform. They then monitor these systems to understand how they are actually performing and reacting to the dynamic conditions of weather, occupancy, and maintenance. This submission includes the Measured Energy Data from the RSF Systems Model. The data includes a csv with measured data from NREL's Research and Support Facility (RSF) for 2011. The dataset contains hourly data for: Total Cooling (kW)- Total Heating (kW)- Total Mechanical (kW)- Total Lighting (kW)- Total Plug Loads (kW)- Total Data Center (kW)- Total Building (kW)- PV (kW)- Building Net (kW). Energy Model data and Weather data related to the RSF Systems Model can be found in the "Related Datasets" section of this submission.

2011↗

Aerosol Impacts on California Winter Clouds and Precipitation during CalWater 2011: Local Pollution versus Long-Range Transported Dust

Mineral dust aerosols often observed over California in winter and spring, associated with long-range transport from Asia and Sahara, have been linked to enhanced precipitation based on observations. Local anthropogenic pollution, on the other hand, was shown in previous observational and modeling studies to reduce precipitation. Here we incorporate recent developments in ice nucleation parameterizations to link aerosols with ice crystal formation in a spectral-bin cloud microphysical model coupled with the Weather Research and Forecasting (WRF) model, to examine the relative and combined impacts of dust and local pollution particles on cloud properties and precipitation type and intensity. Simulations are carried out for two cloud cases with contrasting meteorology and cloud dynamics that occurred on February 16 (FEB16) and March 02 (MAR02) from the CalWater 2011 field campaign. In both cases, observations show the presence of dust and biological particles in a relative pristine environment. The simulated cloud microphysical properties and precipitation show reasonable agreement with aircraft and surface measurements. Model sensitivity experiments indicate that in the pristine environment, the dust and biological aerosol layers increase the accumulated precipitation by 10-20% from the Central Valley to the Sierra Nevada Mountains for both FEB16 and MAR02 due to a ~40% increase in snow formation, validating the observational hypothesis. Model results show that local pollution increases precipitation over the windward slope of the mountains by few percent due to increased snow formation when dust is present but reduces precipitation by 5-8% if dust is removed on FEB16. The effects of local pollution on cloud microphysics and precipitation strongly depend on meteorology including the strength of the Sierra Barrier Jet, and cloud dynamics. This study further underscores the importance of the interactions between local pollution, dust, and environmental conditions for assessing aerosol effects on cold season precipitation in California.

aerosol impacts↗

Earthquake stress via event ratio levels: Application to the 2011 and 2016 Oklahoma seismic sequences

Abstract We develop a new methodology for determining earthquake stress drop and apparent stress values via spectral ratio asymptotic levels. With sufficient bandwidth, the stress ratio for a pair of events can be directly related to these low‐ and high‐frequency levels. This avoids the need to assume a particular spectral model and derive stress drop from cubed corner frequency measures. The method can be applied to spectral ratios for any pair of closely related earthquakes and is particularly well suited for coda envelope methods that provide good azimuthally averaged, point‐source measures. We apply the new method to the 2011 Prague and 2016 Pawnee earthquake sequences in Oklahoma. The sequences show stress scaling with size and depth, with the largest events having apparent stress levels near 1 MPa and smaller and/or shallower events having systematically lower stress values.

58 GEOSCIENCES↗

An evaluation of author productivity in international radiography journals 2004–2011

Radiography, the allied health profession, has changed beyond recognition over the last century; however, in academic terms radiography is a relatively young profession. It is therefore still establishing its professional knowledge base. This article uses peer-review author productivity distribution to evaluate its scholarly maturity. Four peer-reviewed journals in medical radiation sciences were examined over an 8-year period (2004–2011) and author productivity was compared to Lotka's law. Further analysis of the most prolific authors provided an evaluation of their characteristics. The 1306 unique authors contributed 835 articles during the study period. Of these, 1012 (77.5%) contributed only one article to the journals studied, with an inverse power relationship of author productivity. At the 0.1 level of significance, radiography does not fit Lotka's law (n = −2.334; c = 0.712; D{sub max} = 0.0627; Critical threshold = 0.0337). There was a significant correlation between the most prolific authors and collaboration (P = 0.002), although variation was noted in author discipline and location. The results of this study add to the discussion of radiography scholarship and demonstrate that the radiography authors have similar productivity distribution to other professions, but do not follow Lotka's law.

62 RADIOLOGY AND NUCLEAR MEDICINE↗