Mountain Road, VA, United States
Mountain Road, VA, United States

Time filter

Source Type

Buxton V.L.,University of Illinois at Urbana - Champaign | Sperry J.H.,Engineer Research and Development Center
BioScience | Year: 2017

The selection of breeding habitat has broadscale implications for species distributions and community structure and smaller-scale ramifications for offspring survival and parental fitness. In anurans, offspring deposition is a decisionmaking process that involves the assessment of multiple factors at a breeding site, including the presence of predators and competitors. Evolutionary theory predicts that adult anurans should seek to minimize the risk of predation to offspring, reduce the pressure of competition, and maximize offspring survival. Many experimental studies have demonstrated the ability of anurans to assess deposition sites for predation and competition and to choose accordingly, but our understanding of the various ecological factors involved in site choice and the broader consequences of choice is still limited. Here, we review and synthesize the literature on the influence of predators and competitors on anuran deposition behavior. We highlight current gaps in our understanding of this topic and outline future avenues of research.


SEATTLE, Nov. 07, 2016 (GLOBE NEWSWIRE) -- Global supercomputer leader Cray Inc. (Nasdaq:CRAY) today announced the Department of Defense (DoD) High Performance Computing Modernization Program (HPCMP) has awarded the Company with a $26 million supercomputer contract for a Cray® XC40™ supercomputer and three Cray Sonexion® storage systems. The Cray systems will be located at the U.S. Army Engineer Research and Development Center DoD Supercomputing Resource Center (ERDC DSRC) in Vicksburg, Mississippi. As the research organization of the U.S. Army Corps of Engineers, ERDC conducts R&D in support of the soldier, military installations, and civil works projects, as well as for other federal agencies, state and municipal authorities, and with U.S. industry through innovative work agreements. ERDC will use its Cray XC40 supercomputer and Cray Sonexion storage systems in support of its mission to develop innovative solutions for a safer, better world. “It is imperative that ERDC DSRC continue to accelerate technology development by providing researchers and scientists with highly-advanced supercomputing technologies,” said Bobby Hunter, Director of the ERDC DSRC. “Cray supercomputers have played a significant role in the HPCMP and the ERDC DSRC, for several decades. We are pleased that our partnership with Cray will continue in support of our vision of using advanced computational environments to solve DoD’s most critical mission challenges.” “ERDC is one of the world’s premier engineering and scientific research organizations, and we are honored to once again provide its research teams with innovative supercomputing and storage technologies through the DoD High Performance Computing Modernization Program,” said Fred Kohout, senior vice president and chief marketing officer at Cray. “Cray has enjoyed a long history with the DoD and the ERDC, and we are excited that our long-term collaboration supporting their important mission will continue.” Awarded by U.S. Army Engineering and Support Center in Huntsville, Alabama, the contract is valued at approximately $26 million in product revenue. The system is expected to be installed in mid-2017. The new system will include Intel® Xeon® E5 computing cores, as well as Intel® Xeon Phi™ processors, formerly code-named “Knights Landing”, and will be the first-ever production-ready Knights Landing system for the HPCMP. In operation for more than 20 years, the DoD HPCMP remains focused on its mission to accelerate technology development and transition into superior defense capabilities through the strategic application of high performance computing, networking and computational expertise. The HPCMP provides the people, expertise and technologies that increase the productivity of the DoD’s Research, Development, Test and Evaluation community. Cray has worked closely with the HPCMP since its inception. For more information on the Cray XC series of supercomputers  and Cray Sonexion storage systems, please visit the Cray website at www.cray.com. About the DoD High Performance Computing Modernization Program The HPCMP provides Department of Defense supercomputing capabilities, high-speed network communications and computational science expertise that enable DoD scientists and engineers to conduct a wide-range of focused research, development and test activities. This partnership puts advanced technology in the hands of U.S. forces more quickly, less expensively, and with greater certainty of success. Today, the HPCMP provides a complete advanced computing environment for the DoD that includes unique expertise in software development and system design, powerful high performance computing systems, and a premier wide-area research network. The HPCMP is managed on behalf of the Department of Defense by the U.S. Army Engineer Research and Development Center. For more information, please visit the DoD HPCMP website at www.hpc.mil. About Cray Inc. Global supercomputing leader Cray Inc. (Nasdaq:CRAY) provides innovative systems and solutions enabling scientists and engineers in industry, academia and government to meet existing and future simulation and analytics challenges. Leveraging more than 40 years of experience in developing and servicing the world’s most advanced supercomputers, Cray offers a comprehensive portfolio of supercomputers and big data storage and analytics solutions delivering unrivaled performance, efficiency and scalability. Cray’s Adaptive Supercomputing vision is focused on delivering innovative next-generation products that integrate diverse processing technologies into a unified architecture, allowing customers to meet the market’s continued demand for realized performance. Go to www.cray.com for more information. Safe Harbor Statement This press release contains forward-looking statements within the meaning of Section 21E of the Securities Exchange Act of 1934 and Section 27A of the Securities Act of 1933, including, but not limited to, statements related to the timing and delivery of the system purchased by DoD HPCMP and Cray’s ability to deliver a system that meets the DoD HPCMP’s requirements. These statements involve current expectations, forecasts of future events and other statements that are not historical facts. Inaccurate assumptions and known and unknown risks and uncertainties can affect the accuracy of forward-looking statements and cause actual results to differ materially from those anticipated by these forward-looking statements. Factors that could affect actual future events or results include, but are not limited to, the risk that the system required by DoD HPCMP is not delivered in a timely fashion or does not perform as expected and such other risks as identified in the Company’s quarterly report on Form 10-Q for the quarter ended September 30, 2016, and from time to time in other reports filed by Cray with the U.S. Securities and Exchange Commission. You should not rely unduly on these forward-looking statements, which apply only as of the date of this release. Cray undertakes no duty to publicly announce or report revisions to these statements as new information becomes available that may change the Company’s expectations. Cray, the stylized CRAY mark and SONEXION are registered trademarks of Cray Inc. in the United States and other countries, and XC40 is a trademark of Cray Inc. Other product and service names mentioned herein are the trademarks of their respective owners.


East E.W.,Engineer Research and Development Center | Nisbet N.,AEC3 Ltd. | Liebich T.,AEC3 Deutschland GmbH
Journal of Computing in Civil Engineering | Year: 2013

Current specifications for facility handover information require contractors to produce and deliver a set of documents that provide little practical value to the facility manager. Facility managers begin their duties by rekeying the information found in these handover documents. This paper describes the facility management handover (FM) model view definition (MVD), an open-standard information exchange format that may replace current construction handover document requirements. The work was accomplished in conjunction with three buildingSMART chapters to ensure the widest possible international acceptance. The specification of the underlying industry foundation class (IFC) model with required business rules for use in the United States is called the construction-operations building information exchange (COBie) format. Procedures used to test software production and consumption of COBie were developed. Use of COBie has now been documented in several case studies. © 2013 American Society of Civil Engineers.


Houston J.R.,Engineer Research and Development Center | Dean R.G.,University of Florida
Journal of Coastal Research | Year: 2011

Without sea-level acceleration, the 20th-century sea-level trend of 1.7 mm/y would produce a rise of only approximately 0.15 m from 2010 to 2100; therefore, sea-level acceleration is a critical component of projected sea-level rise. To determine this acceleration, we analyze monthly-averaged records for 57 U.S. tide gauges in the Permanent Service for Mean Sea Level (PSMSL) data base that have lengths of 60-156 years. Least-squares quadratic analysis of each of the 57 records are performed to quantify accelerations, and 25 gauge records having data spanning from 1930 to 2010 are analyzed. In both cases we obtain small average sea-level decelerations. To compare these results with worldwide data, we extend the analysis of Douglas (1992) by an additional 25 years and analyze revised data of Church and White (2006) from 1930 to 2007 and also obtain small sea-level decelerations similar to those we obtain from U.S. gauge records. © 2011, the Coastal Education & Research Foundation (CERF).


Houston J.R.,Engineer Research and Development Center | Dean R.G.,University of Florida
Journal of Coastal Research | Year: 2013

Previous research has shown that sea-level acceleration determined from individual tide gauge records has remarkably large scatter as record lengths decrease due to decadal variations in sea level. We extend previous data sets to the present time and find even greater acceleration scatter. Using analytic solutions, sinusoidal oscillations with amplitudes and periods of typical decadal variations are shown to basically account for the relationship between record length and both acceleration and trend difference. Data show that decadal variations will obscure estimates of underlying accelerations if record lengths of individual gauges are not greater than at least 75 years. Although worldwide data are less affected by decadal variations than individual gauge data, decadal variations still significantly affect estimates of underlying accelerations, in particular for record lengths less than about 60 years. We give two examples of recent studies that use record lengths of about 30 to 60 years to determine acceleration or related trend difference. Previous authors dismissed the importance of decadal variations on their results and, as a result, reached invalid conclusions. © 2012, the Coastal Education & Research Foundation (CERF).


Houston J.R.,Engineer Research and Development Center | Dean R.G.,University of Florida
Journal of Coastal Research | Year: 2012

Glacial isostatic adjustment (GIA) is routinely used to adjust sea-level trends determined from tide-gauge data to improve estimates of worldwide sea-level rise. This adjustment may be appropriate for formerly glaciated high-latitude (referred to as FGHL) areas where vertical land motions due to GIA are large compared with motions produced by other phenomena. However, since GIA is only one component of vertical motion, does adjusting for it outside FGHL areas improve sea-level rise estimates or bias them? We compare global positioning system (GPS) gauge measurements with the vertical land-motion component of GIA predictions at 147 worldwide locations that are near tide gauges and outside FGHL areas and find remarkably little correlation. We analyze the data in several ways to determine the source of the lack of correlation. We also find that the average vertical motion for the 147 locations measured by GPS is subsidence, whereas the average GIA prediction is zero. © 2012 Coastal Education & Research Foundation.


Dean R.G.,University of Florida | Houston J.R.,Engineer Research and Development Center
Coastal Engineering | Year: 2013

A comprehensive set of 456 monthly tide gauge records is analyzed for trend and acceleration over the same period that satellite altimetry was analyzed (1993 to 2011). Additionally, a 90 tide gauge record subset is analyzed for which GPS data are available. The selection criterion for the tide gauge data is 85% data completion. All measurements are adjusted for vertical land motion. Results from 456 pairs of tide gauges, adjusted for Global Isostatic Adjustment, and satellite recordings located within 1° root-mean-square latitude and longitude separation differences are compared. The tide gauge trends and accelerations are adjusted for spatial bias using the more globally dense satellite data.The average trends of the 456 and 90 gauge sets (3.26 and 2.68. mm/year, respectively) agree reasonably well with the global trend average of the satellite data (3.09. mm/year). Average trends for the 456 tide gauges are also in good agreement (within 95% confidence limits) with trends based on satellite data within the 1° satellite proximity criterion (3.26 and 3.31. mm/year, respectively). The trends for the 90 gauges with GPS nearby and qualifying satellite locations are 2.68 and 2.74. mm/year, respectively. For all datasets analyzed, the accelerations are quite strongly negative but the uncertainty is relatively large. Adjustment of the tide gauge trends for spatial bias modified both trends and accelerations significantly and decreased trend differences between the 456 and 90 gauge datasets. The spatially adjusted tide gauge trends (2.95 and 2.72. mm/year, respectively for the 456 and 90 tide gauges sets) are somewhat less than the 1° spatially adjusted satellite data (3.09. mm/year). Whether the increased sea level trend of approximately 3. mm/year measured by the satellites since the 1990's is a long-term increase from the 20th Century value of approximately 1.7. mm/year or part of a cycle will require longer records; however, the negative accelerations support some cyclic character. © 2013 Elsevier B.V.


Shafer D.,Engineer Research and Development Center | Bergstrom P.,National Oceanic and Atmospheric Administration
Restoration Ecology | Year: 2010

The Chesapeake Bay is one of the world's largest estuaries. Dramatic declines in the abundance and distribution of submerged aquatic vegetation (SAV) in the Chesapeake Bay over the last few decades led to a series of management decisions aimed at protecting and restoring SAV populations throughout the bay. In 2003, the Chesapeake Bay Program established a goal of planting 405 ha of SAV by 2008. Realizing that such an ambitious goal would require the development of large-scale approaches to SAV restoration, a comprehensive research effort was organized, involving federal and state agencies, academia, and the private sector. This effort differs from most other SAV restoration programs due to a strong emphasis on the use of seeds rather than plants as planting stock, a decision based on the relatively low labor requirements of seeding. Much of the research has focused on the development of tools and techniques for using seeds in large-scale SAV restoration. Since this research initiative began, an average of 13.4 ha/year of SAV has been planted in the Chesapeake Bay, compared to an average rate of 3.6 ha/year during the previous 21 years (1983-2003). The costs of conducting these plantings are on a downward trend as the understanding of the limiting factors increases and as new advances are made in applied research and technology development. Although this effort was focused in the Chesapeake Bay region, the tools and techniques developed as part of this research should be widely applicable to SAV restoration efforts in other areas. © 2010 Society for Ecological Restoration International.


Sharp M.K.,Engineer Research and Development Center
Proceedings of the Institution of Civil Engineers: Geotechnical Engineering | Year: 2011

As part of the Interagency Performance Evaluation Task Force (IPET) investigation into levee breaches in New Orleans following Hurricane Katrina, centrifuge modelling was undertaken of representative levee cross-sections on the 17th Street, Orleans and London Avenue Canals. Two mechanisms were observed leading to breaching of the levee in the models, both of which stemmed from a water-filled crack that formed in front of the flood wall. Depending on the foundation conditions and geometry of the levee and flood wall, the crack led either to a rotation of the flood wall landwards, with uplift and sliding on the top of the sand towards the landward toe of the levee, or to a translational (sliding) failure in the clay layer commencing from the bottom or toe of the flood wall. In the Orleans models no breach ensued, although it was clear these sections were close to failure. The centrifuge model tests identified, at an early stage in the IPET investigation, the importance of the 'gap' mechanism affecting the stability of the flood walls, and confirmed that levee geometry and flood wall depth of penetration, together with the underlying soil profile, were critical to the performance of the system under flood loading.


Tracy F.T.,Engineer Research and Development Center
Procedia Computer Science | Year: 2016

This paper describes a change of variables applied to Richards' equation for steady-state unsaturated seepage flow that makes the numerical representation of the new version of this highly nonlinear partial differential equation (PDE) much easier to solve, and the solution is significantly more accurate. The method is applied to two-dimensional unsaturated steady-state flow in a block of soil that is initially very dry until water is applied at the top. Both a quasi-linear version of relative hydraulic conductivity for which an analytic solution exists and a van Genuchten version of relative hydraulic conductivity are numerically solved using the original and new versions of the governing PDE. Finally, results of this research will be presented in this paper. It was found that for the test problem, the change-of-variables version of the governing PDE was significantly easier to solve and resulted in more accurate solutions than the original version of the PDE. © The Authors. Published by Elsevier B.V.

Loading Engineer Research and Development Center collaborators
Loading Engineer Research and Development Center collaborators