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ARCHIVE - EES Division Highlights/Accomplishments
June 25, 2006 Best Student Paper Award Brian E. Anderson of the Geophysics Group (EES-11) was awarded the Best Student Paper Award in Engineering Acoustics at the 153rd meeting of the Acoustical Society of America in June 2007. The award is given to a student or recent graduate (as in Anderson’s case) based upon the quality of both the content of the paper and its presentation. The award included a $300 cash award. Anderson’s paper consisted of work he did as an acoustics Ph.D. student at Penn State University and was entitled “Grating lobe reduction in transducer arrays through structural filtering of supercritical plates” (Journal of the Acoustical Society of America, vol. 121, p. 3059, May 2007). Transducer arrays are limited in usable frequency bandwidth on the upper end by the appearance of an aliasing effect that results in grating lobes. Grating lobes cause operational confusion for technologies that rely on arrays as they send sound into unintended directions on transmit and increase sensitivity at undesired angles on receive. The paper investigates the idea of eliminating or reducing grating lobes by placing a very stiff and lightweight plate in between the array and the medium to which the array is coupled to. The plate acts as an angular filter to suppress radiation/sensitivity at large angles relative to normal incidence. Grating lobes are reduced as long as they are located in the suppression region. [Work done at the Applied Research Laboratory at The Pennsylvania State University and sponsored by ONR Code 333, Dr.David Drumheller.]
Figure 1. Photograph of a SONAR Tonpilz array bonded onto an advanced ceramic alumina bar. The alumina bar provides the advantageous angular filter to suppress grating lobes at large angles.
Figure 2. Measured beam patterns for the array pictured in Figure 1 without and with the alumina bar (labeled as “with plate”) in place. Note the significant reduction in the grating lobes (green arrows) and the tradeoff increase around +30 degrees due to a phenomena called sound-structure coincidence. June 18, 2006 Invitation to serve on the National Research Council’s committee on seismology and geodynamics Charlotte Rowe (EES-11) was invited to serve as a member of the National Research Council's Committee on Seismology and Geodynamics. The National Research Council is part of the National Academies, which also comprise the National Academy of Sciences, National Academy of Engineering and Institute of Medicine. They are private, nonprofit institutions that provide science, technology, and health policy advice under a Congressional charter. The National Academy of Sciences organized the National Research Council in 1916 to associate the broad community of science and technology with the Academy's purposes of furthering knowledge and advising the federal government. The Seismology and Geodynamics Committee’s mission is:
June 4, 2006 Research on Faults published in Bulletin of the Seismological Society of America The Bulletin of the Seismological Society of America recently published a paper entitled "Assessment of a Nonlinear Dynamic Rupture Inversion Technique Applied to a Synthetic Earthquake," by Siobhan Corish, Chris Bradley (EES-11) and Kim Olsen (collaborator at San Diego State University). The paper probes the problem of 'uniqueness' in a given inversion solution for the stored stresses (pre-stress) and friction on a fault just prior to rupture in an earthquake. The relationship of the pre-stress, friction and radiated energy from a fault is extremely nonlinear. As a result, the paper reports that it is more appropriate to present a family of solutions for a particular fault rather than a single 'best-fit' to the observed data. It is hoped that this work will help provide seismologists with a more probabilistic solution to the pre-stress on a ruptured fault.
May 15, 2006 Nuclear Symposium at the Carlsbad High School On May 2, Jean-Francois Lucchini [EES-12, Actinide Chemistry and Repository Science Program (ACRSP) team] organized a daylong Nuclear Symposium for about 100 students studying physics and chemistry at the Carlsbad High School. The goal of this outreach program was to provide the students with a basic knowledge on nuclear science and technology. Through membership with the American Nuclear Society, Lucchini received a Public Information grant and handouts for each student. Because the Waste Isolation Pilot Plant (WIPP) is an important part in the Carlsbad community, last year Lucchini decided to use this wonderful asset to share basic knowledge at the school to encourage students to form their own opinions and help make decisions in the future.Last year’s symposium was such a success that the teachers asked to make this symposium an annual event. This year the focus of the symposium was nuclear power. This was designed to reflect Carlsbad’s growing interest in becoming involved in the DOE Global Nuclear Energy Partnership Program (GNEP). Local scientists affiliated with EES-12, DOE, Sandia National Laboratories, and the Carlsbad Environment Monitoring and Research Center (CEMRC) of New Mexico State University gave the lectures. The lecture session consisted of an overview about radioactivity and nuclear science, presentations of EES-12 and Sandia scientific roles in the WIPP project, the many applications of nuclear science and technology (food irradiation, power for space shuttles and satellites, radiotherapy, sterilizing, and electricity generation), and the complexity of the geopolitics of energy. Roger Nelson, chief scientist with the DOE's Carlsbad Field Office, discussed why many Americans think nuclear power is dangerous. There were three presentations from women scientists in the nuclear field, focused on WIPP related research. Another theme was the mechanism that the students learn science in school, and how scientists can work together with teachers to improve science education. The students toured the Carlsbad CEMRC facility, where the EES-12/ACRSP team labs are located. Activities included videos about the CEMRC's internal dosimetry program and a tour of a portion of the labs. The students learned about various techniques and equipment (spectrophotometry, ICP-MS, gloveboxes, etc.) that are used in the ACRSP lab, and the safety (personal protective equipment, hand/shoe monitor) associated with the work.
May 7, 2006 "Recent Publication highlighted in Discovery Channel News Story, “Why Supercontinents Self-Destruct” Continental flood basalts, among the largest volcanic events on Earth, may sometimes form solely in response to the blanketing effect of supercontinents. These findings are reported by Benjamin Phillips (EES–6/11) and colleagues in the May, 2007 issue of Geology (N. Coltice, B.R. Phillips, H. Bertrand, Y. Ricard, P. Rey, 2007, “Global Warming of the Mantle at the Origin of Flood Basalts over Supercontinents,” Geology, v. 35, p. 391–394) and highlighted in a recent Discovery Channel News story (“Why Super-continents Self-Destruct”, http://dsc.discovery.com/news/2007/05/01/supercontinent_pla. html?category=earth). Phillips is a Director’s Postdoctoral Fellow. Continents episodically cluster together into a supercontinent. The breakup of supercontinents is often associated with intense magmatic activity at the origin of continental flood basalts. This temporal coincidence, together with domal uplift of the lithosphere and subsequent hotspot tracks rooted in the breakup sites, has led to the hypothesis that a deep mantle plume head could soften the lithosphere, initiate rifting, and trigger continental flood basalt emplacement. The largest Phanerozoic continental flood basalt on Earth (~10 million km2) is the Central Atlantic Magmatic Province (CAMP), which was emplaced with a peak rate 199 million years ago during the initial breakup of the supercontinent of Pangea. CAMP is often cited as a reference example of a plume-derived continental flood basalt, yet this hypothesis is severely debated due to the spatial distribution and chemistry of the lavas and the lack of an identified hotspot track. Coltice et al. propose an alternate non-plume model for the generation of the CAMP on the basis of numerical simulations of mantle convection involving continents. They show that continental aggregation favors longer length scales of flow and naturally generates a broad subcontinental warming of 100° C without the involvement of hot, active plumes (Figures 2, 3). Such a large-scale thermal anomaly would be sufficient to trigger partial melting beneath the supercontinent, especially if the lithospheric mantle were hydrated. While the plume model fits the observations for typical traps like the Deccan in India (high rate of magma supply producing a thick lava pile, hotspot track), the global warming model accounts for the characteristics of the CAMP (wider surface area but thinner lava pile, no hotspot track). The researchers propose two end members: (1) plume-derived and (2) global warming-derived continental flood basalts.
Figure 2. Temperature field snapshots for models with (A) a supercontinent and (B) two antipodal continents. The mean temperature at the base of the continental thermal boundary layer in (A) is 1614 ºC (red), while in (B), it is only 1475 ºC (yellow). Translucent caps denote continent locations. Linear features on planetary surfaces delineate regions of cold, subducting
Figure 3. Subcontinental temperature (averaged over 1 billion years (Gyr) for three-dimensional calculations and 5 Gyr in two-dimensional calculations) as a function of the number of continents at constant continental area (30%). Significant warming occurs when there is a single continent.
Ground-based Nuclear Explosion Monitoring Annual Program Management Review The Air Force Technical Applications Center and the National Nuclear Security Administration’s Annual Program Management Review for Ground-Based Nuclear Explosion Monitoring Research and Engineering was held in Las Vegas, NV. LANL and the NNSA Nevada Site Office (NSO) hosted the meeting at the NNSA/NSO Nevada Support Facility. The meeting included a highly informative, after hours visit to the Atomic Testing Museum. There were over 50 attendees including representatives from NA-22, NA-241, AFTAC, AFRL, ASMDC, DoD, DOS, WINPAC, LLNL, LANL, PNNL, SNL, and others.The theme of the meeting was “Technology Gaps”. In addition to management presentations, there were talks on regions of interest, technology development and knowledge base enhancement. LANL participants were Terry Wallace (PADSTE), Paul Weber (NN), and Ward Hawkins, Scott Phillips, George Randall, Char Rowe, and Diane Baker (all from EES-11). Paper published on First Reported Detection of Meteors Via Infrasound and Seismic Signals Historically, most of the infrasonic recordings from bolides (exploding meteors) have been from quite large meteors at low altitudes. (Infrasound has a frequency too low to be detected by the human ear.) Doug ReVelle (EES-11) and collaborators P.G. Brown and W.N. Edwards (University of Western Ontario); and P. Spurney (Ondrefov Observatory, Czech Republic) have published a paper in which they examined new infrasonic data recorded in an extremely low background noise site in Freyung, Germany. The measurements were made in conjunction with numerous ground-based photographic camera stations operated as a part of the European Fireball Network (EFN). In two years of data analysis for this quiet site, the researchers found four events that absolutely correlate with meteor sources photographed by the EFN (consistent in their timing, directional arrival angles—azimuth and elevation, source energy, optical luminosity, etc.). Four very high-velocity and high-altitude meteors (a Leonid, two Perseids, and a high-speed sporadic fireball) were detected at the ground, both optically using precision all-sky cameras, and acoustically via infrasound and seismic signals. Infrasound arriving from altitudes of over 100 km is uncommon, but has been observed for re-entering spacecraft. This was the first reported unambiguous detection of such high-altitude infrasound from meteors. The fragile meteoroids generated acoustic waves at source heights ranging from 80 to 110 km. Average source energies for three of the four events from acoustic data alone are in the range of 2 x 10 8-9 J. The character of the shock production for the four events is consistent with a ballistic (cylindrical) shock produced along the entire path of the body entry, as opposed to the quasi-spherical acoustic radiation expected for fragment-type shock production. This is not surprising, given the relatively small mass (<1 kg) of the fireballs studied. The researchers combined the data to model the four entries using the LANL bolide luminosity and detection model (BLDM) modeling code, and they also analyzed the infrasound arrivals using Matseis/InfraTool (data processing software). In a planned second paper they will also produce ray tracings of the signals from these line sources along with detailed acoustical dissipation analyses, since these signals emanated from heights ranging from 90-125 km above the ground. In the third planned paper, they will analyze seismic signals from these same four meteors. The first paper, “Acoustic Analysis of Shock Production by very High-altitude Meteors—I: Infrasonic Observations, Dynamics and Luminosity,” was published in the Journal of Atmospheric and Solar-Terrestrial Physics (69, 600-620, 2007). DOE NA-22 supported LANL’s infrasound research.
Figure 1. Left: European Fireball Network image of the Leonid high-altitude meteor from which infrasound has also been measured. Right: Panchromatic lightcurve of the same fireball. The lightcurve was derived from densitometry measurements of the original film records.
Figure 2. Infrasonic pressure wave as recorded by microbarometers for the same Leonid high-altitude meteor April 23, 2007
Mike Fehler receives Distinguished Service to the Seismological Society of America Award The Seismological Society of America (SSA) gave Mike Fehler (EES Division Leader) the Distinguished Service to SSA Award during the SSA annual meeting in Kona, HI. He received the award for serving as the SSA Journal editor for nine years. This award honors individuals who have made outstanding contributions to the work of the Society. Fehler gave a Society-wide address at the annual luncheon, titled “The Role of Scientific Societies in the 21st Century.” As the outgoing president of the SSA, Fehler presented Nafi Toksoz (MIT), EES-11 collaborator and former EES Division Review Committee Chair, with the Harry Fielding Reid Medal. This recognition of the SSA is for outstanding contributions in seismology and earthquake engineering. Photo:Mike Fehler (right) presenting the Harry Fielding Reid Medal to Professor Nafi Toksoz
Annual Meeting of Seismological Society of America (SSA) The world’s leading seismologists gathered in Kona, HI for the 101st Annual meeting of the SSA. The meeting drew nearly 500 national and international scientists, and offered EES researchers the opportunity to present their research and participate in stimulating exchanges of the latest research on earthquakes, volcanoes, nuclear explosions, and more. The outgoing SSA President, Mike Fehler (EES Division Leader), chaired the meeting. Approximately 12 EES scientists gave papers, presented posters, attended talks, and organized, chaired or co-chaired sessions. The LANL scientists who chaired or co-chaired special sessions were:
• Charlotte Rowe (EES-11) co-chaired the session, “New Developments in Semi-automatic and Fully-automatic tools in Seismic Data Analysis.” The contributions covered all aspects of new automation and semi-automation in of seismic data analysis and reporting. • Michael Fehler (EES Division Leader) chaired the session for invited speakers only, “The Future of Seismology.” Speakers speculated on where seismologists will be making significant contributions to science and society in the future—what both basic and applied seismologists will be doing 5 to 20 years from now. • Charlotte Rowe (EES-11) co-chaired the session, “Spinning Straw Into Gold: Improving Our Understanding of Planetary Seismology and Geophysics with New Methods and New Data.” The session explored recent developments in the study of planetary and solar seismology and geophysics. Ten EES Division researchers presented papers and 19 EES scientists authored or co-authored papers that were presented. Many of the presentations were the result of collaborations with industry, government organizations, and universities including LLNL, Weston Geophysical Corporation, Southern Methodist University, Multimax Inc., Cambridge GeoSciences, New Mexico Tech, State University of New York, U. Paris VII, INGV Osservatorio Vesuviano, University of Wisconsin-Madison, Michigan State University, Rensselaer Polytechnic Institute, Tibetan Plateau Uplift Process and Environment Laboratory (Chinese Academy of Sciences), MIT, University of California - Santa Cruz, University of Alaska Fairbanks. For more meeting information: http://www.seismosoc.org/meetings/meetings.html
April 16, 2006 Research on the link between ocean warming and gas hydrates published in a special issue of Journal of Petroleum Science and Engineering Chung-Chieng A. Lai (EES-2) published an invited paper titled, “Effects of gas hydrates on the chemical and physical properties of seawater,” 56, 47-53 (2007), in the Journal of Petroleum Science and Engineering. His paper describes the important role of gas hydrates in the ocean warming and climate dynamics. The global atmospheric warming presents a maximum increase of air temperature at (near) the earth surface where the majority of insolation (influx of solar radiation) is converted into heat. Ocean observations during the last 50 years show that there is an oceanic warming also. However, the place of maximum warming is not at the ocean surface. Instead, it happens at 400 m depth in the Pacific and at 400 m and 750 m depths in the Atlantic. The warming at the ocean surface is secondary. This implies that the mechanism for ocean warming is different from that for atmospheric warming. Traditionally, climate researchers have not believed that the ocean’s internal heat generator, if any, can create a noticeable warming of seawater. This paper not only explains the mechanism, but also presents the evidence found in World Ocean Circulation Experiments (WOCE) data. A variety of gases can form hydrates within the temperature and pressure ranges of seawater. Huge deposits of oceanic methane hydrate (MH) exist on the seafloor on continental margins. After MH breaks off from sediments, it slowly ascends because its density is slightly less than seawater’s. Similarly, nitrogen hydrate is expected to exist in seawater. Further, these gases can form the most common binary hydrates, i.e., methane-nitrogen hydrate (MNH). MNH transforms into water and methane (CH4) and nitrogen (N2) in bubbles when it dissociates at a depth of ~750 m in seawater with a normal temperature profile. Similarly, MH dissociates at a depth of ~400 m. The CH4 may be oxidized (via bacteria) into carbon dioxide (CO2) and releases 810,000 J of heat per mole of CH4 before the bubbles rise to sea surface or dissolve into seawater again. The N2 can be fixed into ammonia (NH3) by microbes and then oxidized into nitrate (NO3-). These biochemical processes deplete the oxygen (O2) dissolved in seawater and generate heat that warms the seawater. Analysis of the relationship among seawater temperature, “apparent oxygen utilization” (AOU) and the concentration of CO2, based on WOCE data, reveals most characteristics that are part of a stoichiometry relation (Figure 1). But, some are not. Analysis of individual station-profiles confirms that the dissociation of gas hydrates occurs according to temperature and pressure (depth) at hydrate phase boundary. Further, the oxygen utilization derived from the concentrations of dissolved CO2 and NO3- matches the AOU very well at a depth greater than the level where hydrates dissociate. The calculated oxygen utilization is slightly less than AOU in the layer of seawater above the level where hydrates dissociate. This is attributed to the escape of CO2 into the atmosphere after it is produced by oxidation reaction. In short, gas hydrates and the microbes play very important roles in altering the chemical and physical properties of seawater and thus affecting the course of climate change. For more information http://dx.doi.org/10.1016/j.petrol.2006.03.030
Figure 1. Scatter plots superimposed with vertical profiles of (a) [CO2] (with AOU), and (b) [nitrate] (with temperature) for 6 stations in Pacific (shown in the map). [CO2] and [nitrate] represent the concentrations (in μ-mol/kg) of dissolved CO2 and nitrate in seawater, respectively. The vertical color bar on the right side of each panel gives the scale of the magnitude of the variable identified on top of each panel (AOU for panel (a), Temperature for panel (b)). The 6 stations are selected according to a set of requirements to be representative of the whole Pacific Ocean. Senate Staff, Congressional Staff, and Committee Members tour Yucca Mountain "Tours" at Yucca Mountain consist of a general briefing of the tunnel/repository layout and experiments (both completed and ongoing). The briefings are conducted in an underground excavation off the main tunnel called an Alcove. This Alcove has been customized for tours, including maps/displays and is about 160 meters (175 yards) underground. On April 4, Brian Dozier (EES-7) conducted a tour and briefing of Yucca Mountain Exploratory Studies Facility for several Senate and Congressional staff and Committee Members (listed below). The information included an overview of geology, results of testing activities and repository layout. The tour also included a stop at the Drift Scale Test about 1.75 miles into the tunnel where a test on the effects of long-term heating of the repository rock is being conducted. Tour visitors included: Alexander McDonough, Legislative Correspondent, Senator Harry Reid Dayle Cristinzio, Legislative Director, Senator Harry Reid Chris Shumway, Legislative Fellow, Senator John Ensign Kevin Kirkeby, Rural Director, Senator John Ensign Tory Mazzola, Communications Director, Senator John Ensign J. Brooke Allmon, Director, Nevada Legislative Affairs, Senator John Ensign Christy C. Guedry, Regional Representative, Senator John Ensign Doug Hampton, Administrative Assistant, Senator John Ensign Samantha Hudson, Reno/Sparks Director, Senator John Ensign Sonia Joya, State Director, Senator John Ensign Judy Treichel, Executive Director, Nevada Nuclear Waste Task Force Steve Frishman, Technical Policy Coordinator, NV Agency for Nuclear Project Jeffrey Wells, Assistant Director, Administrative Services, Clark County Irene Navis, Planning Manager, Clark County Comprehensive Planning Dept. Pamela Thiessen, Legislative Director, Senator John Ensign Donald Tatro, Deputy Press Secretary, Senator John Ensign April 9, 2006 Successful case study in application of geophysics to groundwater Increasingly, concerns about contamination of groundwater resources and the quest for new sources of groundwater drive social and political decisions. To improve the ability to quickly and cheaply characterize groundwater quality and resources, remotely sensed geophysical techniques are being employed. In 2001, EES scientists flew an electromagnetic survey of part of the Pajarito Plateau to characterize local aquifers and contamination pathways. Electromagnetic methods image the electrical resistivity, which is highly sensitive to groundwater, of the outer Earth. The platform was a deHavilland Dash 7 four-engine aircraft carrying a large coil of wires energized by an alternating current (Figure 2). The results, when interpreted with existing geochemical and geophysical borehole data, showed “wet” and “dry” areas of the Plateau to depths of 1000 feet or more, and infiltration beneath some canyons. The work provides a baseline for future detailed studies. When the airborne electromagnetic induction analysis is combined with borehole geologic, hydrologic, and geochemical data, it can provide relative depths to saturated zones, delineate regions of high clay content (zones of alteration), and image regions of recharge to the regional aquifer. The survey, an important case study of the method, is being published in Geophysics [W. S. Baldridge (EES-11), G. L. Cole (EES-9), B. A. Robinson (SPO-CNP), and G. R. Jiracek (San Diego State University)], “Application of time-domain airborne electromagnetic induction to hydrogeologic investigations on the Pajarito Plateau, New Mexico, USA,” v. 72, pp. B31-B45, 2007). The DOE LANL Environmental Restoration Project and the LANL Groundwater Protection Program supported the work.
Figure 2. DeHavilland Dash 7 aircraft, belonging to Fugro Airborne Surveys (Ottawa, Canada), equipped with MEGATEM time-domain electromagnetic induction system for ground-resistivity measurements.
April 2, 2006 Wellbore Integrity Workshop Members of EES Division hosted the 3rd Wellbore Integrity Workshop on March 12-13 in Santa Fe. The workshop focused on a key uncertainty in the long-term performance of geological storage of CO2: the integrity of wellbore systems and their capacity to prevent migration of buoyant CO2 over hundreds of years. The discussions ranged from monitoring and characterization technologies for the wellbore, cement-CO2 interaction experiments and observations, numerical modeling of CO2 in the wellbore environment, numerical modeling of CO2 migration in the context of a field of wells, and environmental regulation and health effects of CO2 as relates to the wellbore environment. The workshop had about 70 participants from oil companies, regulatory agencies, and scientific institutions. The workshop sponsor is the IEA Greenhouse Gas R&D Programme and is part of an effort to coordinate and communicate the latest research on critical issues concerning the viability of carbon capture and storage as a means of confronting greenhouse gas induced global warming.
Figure 2. Schematic diagram of a CO2 sequestration wellbore with observations of the performance of the cement barrier to CO2 migration. |
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